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ABSTRACT
Year : 2010  |  Volume : 25  |  Issue : 3  |  Page : 88-97 Table of Contents   

PET


Date of Web Publication25-Nov-2010

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How to cite this article:
. PET. Indian J Nucl Med 2010;25:88-97

How to cite this URL:
. PET. Indian J Nucl Med [serial online] 2010 [cited 2019 Oct 17];25:88-97. Available from: http://www.ijnm.in/text.asp?2010/25/3/88/72758

PET 01 (ORAL)

Combined imaging approach to Neuroendocrine tumors using somatostatin receptor scintigraphy with 99mTc-HYNIC TOC SPECT/CT and 18 F FDG PET/CT- Implications for targeted peptide therapy

Singh Abhijit, Zade A, Shah Sneha, Purandare CN, Rangarajan V


Department of Radio Diagnosis, Bioimaging Unit, Tata memorial Hospital, Parel, Mumbai - 400 012, India

Introduction: A combined imaging approach using FDG PET (GLUT expression) and SRS (somatostatin Receptor expression) is necessary in order to stratify patients of NET's, for appropriate treatment planning. Aim: 1) To study the variable expression of somatostatin and GLUT receptors in pathologically proven neuroendocrine tumors at primary and metastatic sites. 2) To identify the subgroups and suitability for peptide therapy. Materials and Methods: 72 patients (age - 18-72 years) with a known diagnosis of neuroendocrine tumor were prospectively studied.SRS using 99mTc- HYNIC TOC SPECT/CT and GLUT imaging with FDG PET/CT study were performed in all the patients. The SPECT and PET results were interpreted independently by 2 nuclear medicine physicians and the corresponding studies were compared lesion by lesion for the final analysis. The findings were validated using available histological, imaging and follow up findings. Results: 49 patients had positive findings on both SRS and FDG PET/CT studies.12 patients showed a positive SRS study and negative FDG PET study. 11 patients had a positive FDG PET study and a negative SRS study. A total of 120 lesions were detected on SRS and 131 lesions detected on FDG PET.14 patients had solitary lesions on both the modalities. Neither FDG PET nor SRS added any incremental value in identifying additional sites in patients with solitary lesions. Conclusion: 1) 68% of the patients showed variable expression of somatostatin and GLUT receptors and thus were unsuitable for standalone radio peptide therapy and thus necessitated a combination therapy. The aim would be to control progression or palliation. 2) Only 29% of the patients showed lone somatostatin expression who could benefit from standalone somatostatin or radio peptide therapy with a curative intent.

Keywords: Neuroendocrine, imaging, therapy, HYNIC-TOC, FDG

PET 02 (ORAL)

Role of 131I-MIBG scintigraphy and 18F-DOPA PET/CT in the evaluation phaeochromocytoma/paraganglioma

Kumar Abhishek, Bal CS, Kumari Jyotsana, Gupta Priyanka, Arora Geetanjali, Malhotra A, Bandopadhyaya Guru P, Khangembam BC, Das KJ, Agarwal KK, Sahoo MK, Dhull V, Singhal A


All India Institute of Medical Sciences, India

Phaeochromocytomas are a neuroendocrine tumor of the medulla of the adrenal glands (originating in the chromaffin cells), or extra-adrenal chromaffin tissue that failed to involute after birth. These tumors secrete excessive amounts of catecholamines(epinephrine and norepinephrine) and patients most commonly present with palpitations, anxiety, diaphoresis and hypertension. Diagnosis is established by measuring catecholamines and metanephrines in plasma (blood) or through a 24-hour urine collection, and imaging procedures like ultrasound, CT, 131I - MIBG Scintigraphy and newer modalities like 18F-DOPA PET/CT. In this present study we present our initial experience with of 131I-MIBG scintigraphy and 18F-DOPA PET/CT in the evaluation Phaeochromocytoma/paraganglioma. Sixteen patients with suspicion for phaeochromocytomas/paraganglioma were prospectively enrolled and scheduled for 131I - MIBG and 18F-DOPA PET/CT over a period of 14 months. Whenever possible, tissue diagnosis was attempted. Images were analyzed by two independent nuclear medicine physicians. 131I- MIBG scintigraphy identified eight positive lesions whereas 18F - DOPA PET/CT identified eleven positive lesions. At present, in our clinical experience either of the two tests do not appear to be clearly superior rather they mutually provide additional information in the given clinical setting and should be offered to patient whenever possible.

Keywords: Phaeochromocytoma, paraganglioma, 18F-DOPA PET/CT, 131I - MIBG

PET 03 (POSTER)

Role of 18 F - DOPA PET/CT in evaluation of patients with neuroendocrine tumors (NETs)

Kumar Abhishek, Bal CS, Chumber S, Sellam K, Kundu P, Jeph S, Shukla Jya, Nazar Aftab H, Ramya S, Singh H, Patnecha M, Malhotra A, Bandopadhyaya Guru P


All India Institute Of Medical Sciences, India

NETs are heterogeneous group of tumors which take up amino acids, transform them into biogenic amines and store the amines in vesicles, this forms the basis of uptake of 18F-DOPA in these tumors. These tumors can be small and situated almost throughout the body and may also present as advanced disease with multiple metastatic sites. Like in management of any other tumor it is imperative to stage the status of disease in NETs for the effective management of these patients and 18F-DOPA PET/CT is one such imaging modality used in the evaluation of neuroendocrine tumors (NETs). Here is our initial experience using 18F-DOPA PET/CT imaging in these patients. Twenty-seven patients with NETs (carcinoids, medullary thyroid carcinomas, phaeochromocytomas Insulinoma) were prospectively enrolled and scheduled for 18F-DOPA PET/CT. Wherever possible, tissue diagnosis was attempted. Results obtained were compared with other conventional diagnostic procedures (mainly 18F-FDG PET/CT, and 68Ga-DOTANOC PET/CT, and with ultrasound, CT, etc) and with follow-up. 18F-DOPA PET/CT identified 17/24 positive cases in either the primary/metastatic/recurrent tumor. In case of Insulinoma 18F-DOPA was found to be most superior than other imaging modalities in localizing the disease and staging of disease.

Keywords: Neuroendocrine tumors, 18F DOPA PET-CT, imaging

PET 04 (POSTER)

F-18 FDG PET/CT in differential diagnosis of Parkinsonian disorders

Deepa, Moon S, Mahajan S, Thapa P, Gupta P, Sahana, 2 Batla A, 2 Nehru R, 3 Kushwaha S, 1 Mishra AK, Tripathi M, Sharma R, Mondal A


Division of Clinical PET and 1 DCRS, Institute of Nuclear Medicine and Allied Sciences, 2 G B Pant Hospital Delhi, 3 Institute Of Human Behaviour And Allied Sciences, Delhi, India

Differential diagnosis of Parkinsonian disorders can be challenging in the early phase of disease course. Positron Emission Tomography(PET) imaging with F-18 Fluorodeoxyglucose (FDG) has been used to identify characteristic patterns of glucose metabolism in patients with idiopathic Parkinson's Disease (PD) as well as variant forms of  Parkinsonism More Details such as Multisystem Atrophy (MSA), Progressive Supranuclear Palsy (PSP) and cortico basal ganglionic degeneration (CBGD). In this study we assessed the utility of F-18 FDG PET/CT in the differential diagnosis Parkinsonian syndromes. 66 Parkinsonian patients with a mean age of 59.6+ 11.50 years, male: female ratio of 3.12:1, age range of 35-84 years with a disease duration of 2.6+ .68 years were referred for FDG PET to determine whether their scan patterns could distinguish idiopathic Parkinsons from the Parkinson plus syndromes. Approximately 60 minutes following intravenous injection of 370 MBq of 18 F-FDG, PET/CT scan of the brain was acquired in a whole-body Full Ring PET/CT scanner (Discovery STE16 camera). A low dose CT was obtained on the same area without IV contrast for attenuation correction and coregistration. Images were reconstructed using a 3D VUE algorithm and slices were reformatted into transaxial, coronal and sagittal views. Subsequently the images were processed and visually analyzed on Xeleris workstation. Images were classified by visual analysis into the various subgroups, those with normal to increased basal ganglia uptake were classified into Idiopathic Parkinson's (40/45) and when basal ganglia uptake was decreased they were Parkinsons Plus (19/21). The study demonstrates that F-18 FDG PET performed at the time of initial referral for parkinsonism could accurately classify patients into Parkinson's disease and Parkinson plus subtypes.

Keywords: Parkinson's disease, multisystem atrophy, progressive supranuclear palsy, FDG PET

PET 05 (ORAL)

Can FDG PET replace bone marrow biopsy in patients with lymphoma

Shivdasani Divya, Antony J, Krishna BA


P.D. Hinduja Hospital and Medical Research Centre

Appropriate treatment of lymphoma is dependant on accurate staging. Conventional methods use bone marrow biopsy to assess marrow involvement. This procedure is both invasive and limited to only part of the marrow. The role of 18F-FDG PET-CT is now well established in staging and response assessment of lymphoma patients. Currently 18F-FDG PET-CT is under evaluation for its role in marrow involvement. We present our data of retrospective analysis of 30 patients in this context. Totally 30 patients (19 males and 11 females) aged 10-72 years diagnosed with lymphoma (18 Hodgkin's, 12 DLBCL) were included in the study. All patients underwent staging 18F-FDG PET-CT with images acquired on GE Discovery STE camera using standard acquisition protocols. In addition all patients had bone marrow biopsy from conventional sites (unilateral iliac bone) prior to chemotherapy. Patients who were positive for marrow involvement on PET underwent contrast enhanced CT scans to evaluate cortical bone abnormalities. 17/30 patients (56%) were negative for bone/bone marrow involvement on FDG PET and also on biopsy suggesting good correlation.

13 patients were positive on FDG PET of which 8 patients (62%) were also positive on bone marrow biopsy. 5 patients who were negative on biopsy showed single focal marrow lesion (2 patients) or multiple lesions (3 patients) involving femorii, vertebrae or contra lateral iliac bone on PET which were NOT the sites subjected to biopsy evaluation. These lesions were also negative on CECT for any cortical bone abnormality. The interim (2 patients) and post chemotherapy completion (3 patients) PET scans showed resolution of all these marrow lesions. In our study, 5/30 (16%) patients showed bone marrow involvement in sites other than the negative biopsy site highlighting the superior role of 18F- FDG PET-CT in detection of marrow involvement. Hence we conclude that 18F-FDG PET- CT is superior to bone marrow biopsy and can replace bone marrow biopsy in lymphoma patients

Keywords: Lymphoma, marrow biopsy, 18F-FDG-PET

PET 06 (ORAL)

Role of F-18 FDG PET scan to localize tumor in patients of oncogenic osteomalacia

Malhotra Gaurav, Varsha J 1 , Vijaya S 1 , Mukta K,

Asopa V, Shah Nalini S 1 , Padmavathy M 1


Radiation Medicine Centre, BARC, Tata Memorial Centre Annexe, Mumbai. 1 Department of Endocrinology, Seth G S Medical College and KEM Hospital, Mumbai, India

Background: Oncogenic osteomalacia is a rare paraneoplastic syndrome of renal phosphate wasting which is usually caused by phosphaturic mesenchymal tumors. Conventional radiologic techniques usually fail to detect these small, slow growing neoplasms located at unusual sites. The objective of this study was to evaluate the role of F-18 FDG PET imaging in patients of oncogenic osteomalacia. Materials and Methods: Fifteen patients (8 males and 7 females) [mean age: 38.5±12.2 years] with clinical and biochemical evidence of oncogenic osteomalacia were subjected to 'total' whole body F-18 FDG PET scan including both limbs and skull views. The images were reconstructed and the final output was displayed as per the standard institution protocol. Results: F-18 FDG PET imaging localized suspicious hypermetabolic foci of SUVmax ranging from 1.4 to 3.8 (Mean±S.D: 2.39±0.63) suggesting presence of occult tumor in 11 of 15 patients. The suspected foci were localized in lower limbs in ten patients and in the petrous temporal region of skull in 1 patient. FDG localized tumors were histopathologically correlated in 6 patients who underwent surgical biopsy/excision after correlative radiological investigations. Four of these patients were cured after surgical excision while partial surgical excision/biopsy was performed in two patients. Conclusions: F-18 FDG PET imaging is a promising technique for detection of occult tumors in patients of oncogenic osteomalacia. It is mandatory to include limbs in the field as these tumors are common in limbs and may be easily missed. Preoperative localization increases odds for cure after surgical removal of tumor.

Keywords: Osteogenic osteomalacia, FDG PET, unknown primary

PET 07 (ORAL)

Initial evaluation of 18 F-NaF, 18 F-FDG and cocktail 18 F-NaF/ 18 F-FDG PET/CT for evaluation of skeletal metastasis

Bal Jaspriya, Tripathi M, D'souza Maria M, Panwar P, Singh D, Pandey S, Nitin, Sharma R, Mishra A, Mondal A


Molecular Imaging and Research Center, Institute of Nuclear Medicine and Allied Sciences, New Delhi, India

Introduction: 18F-FDG PET/CT is the commonest radiotracer used for initial staging of malignancy and subsequent treatment strategy evaluation while Sodium 18F PET/CT is a favoured skeletal radiotracer in oncology. The combined administration of 18F and 18F-FDG in a single PET/CT study can be done for cancer detection and initial staging. Materials and Methods: This is a prospective study (July '09-June '10) of 18 patients with histologically proven malignancy, for initial staging (10 carcinoma breast, 2 carcinoma lung, 1 carcinoma prostate, 3 NHL and 2 carcinoma salivary glands) who underwent 18F PET/CT, 18F-FDG PET/CT and combined 18F+18F-FDG PET/CT (cocktail) study on different days for evaluation of malignancy (a total of 3 scans each). There were 7 males and 11 females, age 48±1.4 yrs (range 20-72 yrs). The findings of each study were compared lesion by lesion, with bone marrow aspiration/biopsy/MRI being the reference standard for marrow metastasis and follow up/CT being the reference standard for metastatic lesions. Results: Interpretation of the combined scans (1 lesion missed) compared favourably with that of 18 F-FDG PET/CT (2 lesions missed) and 18F PET/CT scan (3 lesions missed). The cocktail and 18F-FDG PET/CT study demonstrated a sensitivity of 93.75% and 87% respectively, but both had equal utility for detection of marrow metastasis. However, the 18F PET/CT study revealed lowest sensitivity 81% but similar specificity i.e. 50% as the cocktail study. 18F-FDG study gave the highest specificity (100%) out of the three. Conclusion: The prospective study demonstrated that a cocktail study using 18F and 18F-FDG is beneficial for cancer detection and initial staging. The combined method opens the feasibility for detection of the visceral, skeletal and marrow metastasis in a single sitting, improving the patient logistic and turnover and with the current CT co-registration, the false positives can be ruled out.

Keywords: 18F, 18F-FDG, PET/CT, malignany

PET 08 (POSTER)

Is FDG PET/CT scan superior to Ca-125 levels in management of recurrent ovarian carcinoma

Gupta Khushboo, Krishna BA, Singh Natasha, Mishra Rohini, Shivdasani D, Moyade P


P.D. Hinduja National Hospital and Medical Research Centre, Mahim, Mumbai, Maharashtra, India

In the post-operative surveillance of ovarian carcinoma patients, the CA-125 levels play an important role. However there is no direct relationship between the level of CA-125 and the metastatic volume. Hence FDG-PET scan would play a major role in the detection and quantification of the metastatic disease burden. We present our retrospective analysis of 30 ovarian carcinoma patients in this context. Totally 30 patient were included in the study. All patients had CA-125 estimation as part of regular follow up after initial surgery. All those patients who had elevated CA-125 levels were further investigated with either CT/MRI/USG initially followed by PET-CT scan in those patients where focal disease was detected by one of the 3 anatomical modalities. For purpose of analysis patients were grouped into 3 categories based on CA-125 levels: Group A: CA-125 - 0 to 35 IU/ml (n=10), Group B: CA-125 35 to 70 IU/ml (n=6), Group C: CA-125->70 IU/ml (n=14). The volume of disease detected on PET/CT scan was correlated with CA-125 levels and also its impact on treatment approach was analysed. In Group A - 3 patients had no disease (no treatment given), 6 had distant metastasis (chemotherapy) and 1 had localized disease (surgical excision). Group B - 2 patients had localized disease (surgery + chemotherapy in one patient) and 4 had distant metastasis (chemotherapy). Group C - 13 patients had distant metastasis including lungs (2 patients) and bones (4 patients) (chemotherapy + radiotherapy), and 1 patient had localized disease (surgical removal). Out of 30 patients, there were 8 patients (26.6%) who showed solitary lesions on CT scan, however in 3 of these 8 patients PET/CT scans showed multiple sites resulting in 37.5% upstaging and thereby change of therapy in the form of surgery to systemic chemotherapy. From our analysis we conclude that the CA-125 levels correlated well with volume of metastatic disease on PET/CT in higher range (CA-125: >70 IU/ml) while in the lower range (CA-125: 0-35 IU/ml) the same correlation was not observed. Hence PET/CT would be superior to CA-125 in accurate assessment of metastatic burden. We also conclude that PET/CT upstages the disease and thereby alters the therapeutic approach in 38% of patients.

Keywords: FDG PET/CT, Ca-125, ovarian carcinoma, management

PET 09 (POSTER)

Comparative evaluation of C-11 methionine (MET-PET) and F-18 flurodeoxyglucose (FDG) PET/CT for detection of recurrent brain tumors

Tripathi Madhavi, 1 Varshney Raunak, Sharma Rajnish, Bal Jaspriya, Jaimini Abhinav, Souza MD Maria, Pandey Santosh K, 2 Jain Jyotika, 1 Panwar Puja, Mishra Anil K and Mondal Anupam


Division of Clinical PET and 1 DCRS, INMAS, Delhi-54. 2 Delhi State Cancer Hospital, DSCI, Shahadara, Delhi, India

Aim: Comparative evaluation of C-11 Methionine (MET-PET) and F-18 flurodeoxyglucose (FDG) PET/CT for detection of recurrent brain tumors. Patients and Methods: 23 post-operative, histologically proven cases of primary brain tumors were included; there were two cases of grade I (WHO), 9 cases of grade II, 5 cases of grade III, 3 cases of grade IV, 3 medulloblastomas and one gliosarcoma. Ratio of M:F=16:7, age 27.5+14.4 years (range 5-56 years). All patients underwent the MET-PET and FDG-PET scans on the same day. Images were evaluated for recurrence using visual analysis and final results were compared with MRI/MRS and follow up as gold standard. Results: Fourteen cases were positive for recurrence on the MET-PET study while FDG was unequivocally positive in eleven cases. MET-PET scans were true negative for recurrence in nine cases and concurrent with the MRI/MRS findings in all 23 cases. Tumor to background ratio for the MET-PET study were 2.2+.55 Conclusion: MET-PET is superior to FDG-PET for detection of recurrence in both low and high grade gliomas and has excellent correlation with MRI/MRS

Keywords: C-11 methionine, F-18 FDG, PET/CT, brain tumors

PET 10 (ORAL)

(18F) FDG PET/CT in patients with fever of unknown origin: AIIMS experience

Nazar A H, Naswa N, Ramya S, Patnecha M, Bangkim Chandra K H, Kumar R, Bandopadhyaya G P, Bal C S, Malhotra A


All india institute of medical sciences, New Delhi, India

The aim of this study was to assess the value of (18F) FDG PET/CT in evaluation of patients with Fever Of Unknown Origin (FUO). We retrospectively analysed clinical data and (18F) FDG PET scan of 48 patients over a period of 1 year. These patients met the revised definition criteria of FUO (febrile illness of greater than 3 weeks duration, temperature greater than 38.3 C and no diagnosis after appropriate in-patient or out-patient evaluation). Most of the patients recruited in this study had normal clinical and radiological examination. (18F) FDG PET was helpful in making a diagnosis in 24 patients. An infective/inflammatory cause of FUO was found in thirteen (27%) patients, a neoplasm in six (12.5%) patients, autoimmune cause in five (10.4%) patients. A definitive diagnosis could not be made in twenty four (50%) patients. Out of these 24 patients, 15 had normal PET/CT study, 9 had positive PET/CT findings but they lost in follow up and 2 died within 1month of PET/CT study without any diagnosis. (18F) FDG PET/CT is a useful tool for evaluation of patients with FUO. It provides important diagnostic clues not suggested by other conventional imaging modalities. Patients with positive PET/CT findings but no definitive diagnosis should be followed up further to improve utility of PET/CT.

Keywords: Fever of unknown origin, FDG PET, clinical utility

PET 11 (ORAL)

Utility of PET-CT in CT-guided biopsy of lung

masses

Raja S, Patel MA, George SP, Rao V, Bhonsle S, Kobayashi K


Michael E. DeBakey Medical Center, Houston, TX Baylor College of Medicine, Houston, TX, USA

Purpose: CT guided transthoracic biopsies of lung masses is routinely performed, the diagnostic yield in large masses/lesions noted on CT may be decreased due to sampling of necrotic cores, non viable tumor areas, scar or fibrotic tissue. Targeting metabolically active tumor foci could potentially decrease the sampling errors. We sought to retrospectively evaluate the role of PET-CT, in CT guided trans-thoracic biopsies of lung masses greater than 3cms. Materials and Methods: Retrospective analysis of all patients with lung Ca. undergoing PET-CT scanning followed by CT guided trans-thoracic biopsies of lung masses greater than 3 cms. A total of 33 patients were identified by chart reviews, the findings on histopathology were correlated with those of PET-CT findings, statistical analysis were performed on a Excel database. Results: The statistical analysis of PET-CT findings were as follows: Sens=92%, Spec.13%, Acc.=73%, PPV=77%, NPV=33%. The estimated specificity and negative predicative values were low in our series, since only few lesions with absent or metabolically mild lesions on PET were biopsied, while significant number of false positives on FDG PET due chronic inflammation were sampled. Conclusion: Our results suggest that the findings on PET-CT would be helpful in pre-procedural target identification and navigation during CT guided trans-thoracic biopsy of suspected lung masses. In future co registration of PET-CT with diagnostic CT and respiratory gated PET would be helpful in precise targeting. CLINICAL RELEVANCE/APPLICATION In future co registration of PET-CT with diagnostic CT and respiratory gated PET would be helpful in precise targeting.

Keywords: PET-CT, guided biopsy, lung cancer

PET 12 (POSTER)

Evaluation of marrow involvement of lymphoma by FDG PET scan

Gawde Sachin, Shah Sneha, Purandare NC, Gujral S, Nair R, Rangarajan V


Bioimaging Unit, Department of Radio Diagnosis, Tata memorial Hospital, Parel, Mumbai - 400 012, India

Aim: Role of FDG PET/CT scan in detecting marrow disease in biopsy proven cases of high grade lymphoma and to study concordance and discordance between FDG PET scan and bone marrow biopsy. Materials and Methods: Retrospective study comprising of 100 cases (78 males and 22 females) of high grade lymphoma (Hodgkin's lymphoma (30 cases) and NHL (70 cases) during the period January to December 2007. All the patients underwent standard of care bone marrow biopsy (BMB) from the iliac crest to look for marrow involvement and whole body FDG PET/CT scan to look for overall extent of disease burden in the body. 10mCi of FDG was injected IV and whole body PET/CT scan was acquired 60 minutes later. All CT images of FDG-PET/CT scans were analyzed independently regarding morphological osseous changes and compared with FDG-PET results. Marrow FDG uptake at L5/S1 vertebra with SUV max > 2.9 or focal increased uptake was considered significant for marrow involvement. Results: Out of the 100 cases, there was concordance in FDG PET scan and bone marrow biopsy findings in 67 patients (67%) i.e both FDG PET scan and BMB positive in 6 patients. FDG PET scan and BMB negative in 61 patients. Discordance in FDG PET scan and BMB for detecting marrow involvement was found in 33 patients. FDG PET scan positivity and BMB negativity for marrow involvement was seen in 28 patients and FDG PET negativity and BMB positivity in 5 patients. Cortical abnormality on the CT component of the PET/CT scan was observed in 5 patients (3 in axial and 2 in appendicular skeleton. Conclusion: Considering the above data, bone marrow biopsy from iliac crest may be false negative in cases where bone marrow involvement and focal involvement is evident on FDG PET. It might therefore be a better approach to perform biopsy of marrow with FDG PET/CT guidance

Keywords: Lymphoma, marrow involvement, FDG PET

PET 13 (POSTER)

18F-FDOPA PET-CT vs 99mTc-GHA SPECT-CT in evaluation of recurrent brain gliomas

Karunanithi Sellam, Bal C, Gupta D 1 , Malhotra A, Kumar Abhishek, Bandopadhyaya GP


Departments of Nuclear Medicine, and 1 Neurosurgery, AIIMS, New Delhi, India

Objectives: Purpose of this study was to compare the role of 18F-FDOPA PET-CT(FDOPA) and 99mTc-GHA SPECT-CT (GHA) in detecting recurrence in glioma patients. Materials and Methods: Thirty patients of clinically suspected recurrent glioma of varying grades (ten with low grade and twenty with high grade primary tumor), previously treated with surgery and/or radiotherapy were evaluated using FDOPA and GHA. FDOPA images were interpreted positive for any abnormal tracer uptake noted in brain parenchyma. GHA images were interpreted as positive for abnormal tracer uptake noted in brain parenchyma. Final outcome was judged on the basis of biopsy report and/or clinical follow-up and serial MRI/MR spectroscopy imaging results. Results: Twenty- three patients were considered positive (death in 5, biopsy in 2, clinical progression in 6 and progression on imaging in 10) while 7 were negative for recurrence. FDOPA scan was positive in 22, negative in 8 patients. GHA was positive in 21, negative in 9 patients. Sensitivity, specificity, PPV and NPV of FDOPA were 95.6%, 100%, 100% and 87.5%, respectively. Sensitivity, specificity, PPV and NPV of GHA were 82.6%, 71.4%, 90.4% and 55.5%, respectively. Conclusions: FDOPA has the highest detection rate for recurrent glioma irrespective of the grade. FDOPA was found to be superior especially in detecting low grade viable gliomas. GHA, however due to high occurrence of false-positive results, prospective differentiation of recurrent tumor from treatment-induced changes is not possible in most patients

Keywords: FDOPA, GHA, gliomas

PET 14 (ORAL)

Role of F-18 FDG PET/CT in evaluation of bone and soft tissue sarcomas

Moon Sourabh, Deepa, Mahajan S, Thapa P, Gupta P, Sahana, Mishra AK, 1 Jain Jyotika, Tripathi M, Sharma R, Mondal A


Division of Clinical PET, DCRS, Institute of Nuclear Medicine and Allied Sciences, 1 Delhi Cancer Institute, Delhi, India

We reviewed our experience of Positron Emission Tomography/Computed Tomography (PET/CT) with F-18 Fluorodeoxyglucose (FDG) in the evaluation of patients with bone and soft tissue sarcomas. In a retrospective study (August 2007- May 2010) involving 47 patients with histological diagnosis of sarcoma underwent FDG-PET/CT study. Our study included 32 males and 15 females, age 27±17 years (range of 2-75 years) which included 14 patients for staging evaluation and 33 patients for post therapy evaluation. Final comparison was based on clinical follow up/ MRI/ biopsy correlation. Approximately 60 minutes following intravenous injection of 370 MBq of 18 F-FDG, PET/CT scan from the skull to mid thigh was acquired in a whole-body Full Ring PET/CT scanner (Discovery STE16 camera). A low dose CT was obtained on the same area without IV contrast for attenuation correction and coregistration. Images were reconstructed using a 3D VUE algorithm and slices were reformatted into transaxial, coronal and sagittal views. Subsequently the images were processed and visually analyzed on Xeleris workstation.Sensitivity for detection of primary bone and soft tissue sarcoma was 100%. Sensitivity for evaluation of residual disease is 100% with specificity of 98%. Sensitivity and specificity for evaluation of metastasis was 100% and 98% respectively. Lung nodules were reported based on CT findings irrespective of FDG avidity, this improved the detection of lung metastasis. This study demonstrates that combined F-18 FDG PET/CT is an excellent modality for staging and post therapy evaluation of primary bone and soft tissue sarcomas.

Keywords: Sarcoma, PET/CT, prognosis, recurrence, follow up

PET 15 (POSTER)

Role of F18-FDG PET CT in the diagnosis and management of vasculitis: Case based presentation

Dureja Sugandha, Pankaj P, Verma Ritu, Mahajan Harsh


Sir Ganga Ram Hospital Rajinder Nagar New Delhi - 110 060 India

Vasculitis is defined as inflammatory changes and necrosis in the arterial wall and presents commonly as Pyrexia of Unknown Origin (PUO). FDG-PET/CT has proven utility in the initial diagnosis of patients suspected of having vasculitis particularly in those who present with non-specific symptoms or PUO, in the identification of areas of increased FDG uptake in which a biopsy should be done for obtaining a diagnosis, in evaluating the extent of the disease, in assessing response to treatment. FDG PET-CT is an established modality in the diagnosis of large-vessel vasculites with sensitivity values ranging 77% to 92%, and specificity of around 89% to 100%. In particular, FDG-PET/CT has demonstrated the potential to non-invasively diagnose the onset of the vasculitis earlier than traditional anatomical imaging techniques, thus enabling prompt treatment. We present two cases of large vessel vasculitis, presenting as PUO, evaluated by FDG PET CT. The patients presented with fever with other non specific symptoms and elevated inflammatory markers. FDG PET CT demonstrated intense FDG uptake in the vessel walls. Steroid therapy was commenced. Significant symptomatic improvement correlating with normalization of the laboratory data was observed in both the patients. Details of both the cases will be presented

Keywords: F18 FDG PET CT, PUO, vasculitis

PET 16 (POSTER)

Spectrum of findings observed on 18 F-FDG PET CT in primary staging of carcinoma esophagus

Vijayraghavan RL, Jain N, HV Sunil, Selvakumar J


Department of Nuclear Medicine, Narayana Hrudayalaya Institute of Medical Sciences, Bengaluru, India

Background: The incidence of carcinoma esophagus is widely increasing. Unlike the west, the prevalence of squamous cell carcinoma is higher than that of adenocarcinoma in India. Surgical management of carcinoma esophagus depends on M staging. Stage I to stage IVA is considered suitable for surgical resection. Stage IVB is considered unresectable disease and requires palliative treatment. Aim: Evaluation of spectrum of findings observed on FDG PET CT while evaluating the patients for primary staging. Materials and Methods: We studied 14 patients with biopsy proven carcinoma esophagus. All patients underwent 18F-FDG PET CT scan under a dedicated BGO PET-CT scanner. Both oral and IV contrast were used (omnipaque). Average dose injected was 10mCi and patients were imaged after 60 minutes of FDG injection. Each bed position was acquired for 3 minutes. Reconstruction of the acquired data was performed so as to obtain fused PET-CT images in transaxial, coronal and sagittal views. SUV max was calculated in g/mL SUVbw. Results: Out of 14 patients studied, 13 had squamous cell carcinoma (2 well differentiated (Mean SUVmax 20.8), 6 moderately differentiated (Mean SUVmax 16.93) and 4 poorly differentiated (Mean SUVmax 17.85)) and 1 had adenocarcinoma of gastro esophageal junction.7patients had primary disease in mid thoracic esophagus, 5 had lower esophageal disease and 2 had upper esophageal primary disease. 7 out of 14 patients were detected to have M1b disease (distant metastatic lymph nodal / organ disease), making it a Stage IVB unresectable disease. Conclusion: In this study, the higher prevalence of squamous cell carcinoma is highlighted in Indian scenario. The incidence of unresectable disease at presentation is around 50%, unlike west, where distant metastasis at presentation is around 20%-30%. Hence, it can be concluded that 18 F-FDG PET holds a critical role in treatment planning at primary staging for esophageal carcinoma.

Keywords: Carcinoma esophagus, unresectable disease, Stage IVB

PET 17 (ORAL)

18 F-FDG PET-CT in diagnosis of tumor thrombus

Sharma Punit, Kumar Rakesh, Jeph Sunil, Sellam K, Gupta, Malhotra A


Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India

Background: Venous thromboembolism is a relatively common phenomenon in cancer patients while tumor thrombosis is a rare complication of solid cancers. The correct diagnosis of tumor thrombosis and its differentiation from benign thrombus can change patient management and prevent unnecessary anticoagulation treatment. Materials and Methods: We conducted a retrospective review of FDG PET-CT scans of patients who underwent the study between July 2007 and July 2010. Any focal and/or linear area of increased FDG uptake (more than mediastinal blood pool) conforming to a blood vessel was taken as positive. SUVmax of the thrombus, SUVmax of tumor (if any) and SUVmax of mediastinal blood pool were calculated. PET-CT results were confirmed with clinical follow up, structural imaging and histopathology when available. Results: Total 24 patients (15 male and 9 female) with mean age of 43.8 years (range: 3-72; median-47.5) were evaluated. All patients underwent PET/CT for staging or restaging of a known malignancy and had a FDG avid thrombus. Based on structural imaging and clinical follow up, 9 patients had benign thromboembolism and 13 patients had tumor thrombosis. On FDG PET-CT, uptake in the thrombus was linear in 18 patients and focal in 6 patients. The most common site of thrombosis was IVC (n=14) followed by PV (n=7). One patient had catheter associated thrombosis. Four patients had only the thrombus as the FDG avid foci while remaining 18 patients had other FDG avid focus of disease. The mean SUVmax in the benign thrombosis group was 3.2 (range: 2.3-4.6; median-3.3). The mean SUVmax in the tumor thrombosis group was 6.0 (range: 2.3-13.8; median-3.3).There was significant difference in SUVmax between the two groups P = 0.013. On ROC analysis a cut off SUVmax of 3.63 was obtained to differentiate tumor thrombus from benign thromboembolism. In 6 patients FDG PET-CT detected occult vascular thrombosis, which was later confirmed with other imaging modality. Conclusion: FDG PET-CT can detect tumor thrombosis and reliably differentiate it from benign thrombus. Contrast enhanced PET-CT might provide additional information in these patients.

Keywords: Tumor thrombus, FDG, PET-CT

PET 18 (POSTER)

Response evaluation of gastrointestinal stromal tumors treated with imatinib using 18F-FDG PET/CT

Jeph Sunil, Kumar Rakesh, Sharma P, Kumar Abhishek, Maharjan S, Bandohpadhaya GP, Malhotra A


Department of Nuclear Medicine, All India Institute of Medical Sciences, Delhi, India

Background: Several studies have demonstrated the effective use of adjuvant treatment with Imatinib mesylate for unresectable, metastatic or recurrent Gastrointestinal Stromal Tumors (GIST). We retrospectively evaluated the role of 18F-FDG PET/CT scanning in assessing the response of GIST patients to imatinib mesylate therapy. Materials and Methods: Thirteen consecutive patients with GIST confirmed by surgery (5 stomach, 6 small bowel, 1 small bowel and peritoneum, and 1 rectum) underwent 60 18F-FDG PET/CT imaging before and after beginning imatinib mesylate therapy (400 mg/day or greater if disease progression). PET/CT scan was acquired 60 minutes after the intravenous injection of 333-707 MBq of 18F-FDG. Visual and semiquantitative (standardized uptake value [SUV]) analysis of images was performed. A decrease in SUV of more than 50% was considered as significant response, decrease in SUV of more than 25% was considered as partial response. Increase in SUV of more than 25% or appearance of new lesion (s) was considered as progression of disease. Response to therapy was assessed according to EORTC recommendations for PET. Results were confirmed by clinical follow-up, CECT findings or histological analysis (when available). Results: Complete response to imatinib mesylate was observed in 5 patients. Partial response and stable disease was noted in two each. Four patient demonstrated progression of disease, two developed liver metastasis, one developed abdominal lymphnode pathology and one had increase in size and uptake of tumor. Conclusion: 18F-FDG PET/CT scan identified the degree of GIST response to imatinib therapy. Patients who responded to therapy showed normalisation of FDG uptake or a decrease in the SUV of lesions. Patients with progression of disease demonstrated increase in uptake value or development of new lesion.

Keywords: GIST, FDG PET-CT, Imatinib

PET 19 (POSTER)

Treatment response evaluation using 18F-FDG PET-CT in patients with recurrent head and neck cancer

Jeph Sunil, Kumar R, Singh H, Kundu P, Karthik S, Nazar Aftab Hasan, Damle N, Bal CS, Malhotra A


Department of Nuclear Medicine, All India Institute of Medical Sciences, Delhi, India

Background: The five-year survival varies from 20-90% depending upon the sub-site of origin and the clinical extent of disease in head and neck cancer. The present study was aimed to evaluate treatment response in patients with recurrent head and neck cancer (HNN) using 18F-FDG PET-CT. Materials and Methods: A total of 42 patients of recurrent head and neck cancer were analysed retrospectively. The age range was 17 to 83 years with mean age of 48.26 years. All patients had a baseline 18FDG PET-CT scan which showed active disease. Follow-up 18FDG PET-CT scan (post treatment) was done 4-6 weeks after last cycle of chemotherapy, radiotherapy, and surgery. A decrease in SUV of more than 50% was considered as significant response, decrease in SUV of more than 25% was considered as partial response. Increase in SUV of more than 25% or appearance of new lesion (s) was considered as progression of disease. Results: Of 42, Nineteen patients underwent only chemotherapy, 5 patients showed significant response (SR), 2 showed stable disease (SD) and 12 had progression disease (PD). Of 42, 13 patients underwent combined chemotherapy and radiotherapy, 5 had significant response (SR), while progression of disease was noted in 8 patients. Of 42, 7 patients had only radiotherapy, 6 had significant response (SR) while one had stable disease. A combination of chemo-radiotherapy and surgery was given to 3 of 42 patients, 2 had significant response while stable disease was found in one. Conclusion: 18FDG PET-CT is a useful non-invasive modality in evaluating treatment response in recurrent head and neck cancer. Early recognition of resistance to chemotherapy can result in lower cumulative treatment toxicity.

Keywords: Head and neck cancer, FDG PET-CT, recurrent

PET 20 (POSTER)

Role of whole body PET/CT in detecting distant metastasis in head and neck cancer

Kamaleshwaran KK, Bhattacharya A, Harishankar CNB, Manohar K, Singh B, Mittal BR


Department of Nuclear Medicine and PET Centre, Postgraduate Institute of Medical Education and Research, Chandigarh, India

Background: The incidence of distant metastases in patients with Head And Neck Cancers (HNC) is smaller ranging from 4 to 25%, with the lungs, bones and liver being the most frequent sites. 18F-Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET)/Computer Tomography (CT) has shown more sensitivity in detecting unsuspected distant metastasis. Several reports indicate that for HNC a whole body may yield little additional information. So our aim was to evaluate the role of whole body PET/CT in detecting the distant metastasis in HNC. Materials and Methods: An analysis of 34 consecutive FDG PET-CT scans of head & neck cancers (Pharyngeal 3, Laryngeal 3, tongue 13, oral cavity 3, alveolar 2, maxillary sinus 1, tonsil 3, thyroid 4). Out of 34 patients, 19 were referred for initial staging and remaining 15 for restaging. Results: In staging group, FDG PET detected distant abnormalities in two patients in lung and adrenal. In restaging group, 2 patients were found to have distant metastatic lesions in lung, liver and bone was confirmed after biopsy. So therapy planning has been changed by whole body PET/CT in 1 during initial-staging and 2 during restaging. Conclusion: The detection of distant metastases at the time of initial evaluation and during restaging changes the prognosis and influences the selection of treatment modality in patients with HNC. While FDG-PET/CT had high sensitivity, specificity, and negative predictive value, it had a lower positive predictive value, suggesting that additional diagnostic methods are essential to rule out false positives and to avoid false upstaging to M1 for appropriate therapeutic planning.

Keywords: FDG PET-CT, head and neck cancer, metastases

PET 21 (POSTER)

Retrospective analysis of low FDG concentrating tumors and their comparison with the conventional imaging modalities and to assess the role of 18F-FDG-PET In follow-up of these patients

Sonik Atwal Yasmeen, Agrawal A, Basu S, Asopa R


Radiation Medicine Centre, Bhabha Atomic Research Centre, Parel, Mumbai - 400 012, India

Background: (18F)FDG PET has been known to have insufficient sensitivity for the detection of low (18F)FDG concentrating tumors. We retrospectively evaluated the value of (18F)FDG PET for the detection of primary and metastatic low FDG concentrating tumors. Aim: 1. To validate the value of (18F)FDG for the detection of primary and metastatic disease in known low FDG concentrating tumors in comparison with radiological modality and its effect on diagnosis and treatment of the same. 2. To determine the% of new, concurrent and missed lesions in our study and to predict role of (18F)FDG in follow-up of these patients. Materials and Methods: Histologically proven cases of respective tumor pathology, who had undergone (18F)FDG PET scan at our Centre (RMC) from the year 2003 to 2009, were selected for the study. This comprised of Renal cell carcinoma (n=24), Hepatocellular carcinoma(n=5) and Maltoma (n=5). Patient-by-patient and lesion-by-lesion analysis of 18F-FDG PET scan findings was done in comparison with conventional imaging modalities in each group. Percentages of new, concurrent and missed lesions on PET were calculated in respect to the conventional imaging modalities. Where possible, the SUVmax values of lesions (corrected for body weight) were calculated and compared with the results of the previous studies. Results: 18F-FDG PET scan findings were compared with the conventional imaging modalities in each sub group of both categories. Patient by patient analysis and lesion-by-lesion analysis of the data was done. This was used for calculating percentages of new, concurrent and inactive lesions on PET as compared to the conventional imaging modalities. The observations were as follows- PET detected 39% new lesions in patients of renal cell carcinoma (RCC), 57% in Hepatocellular carcinoma (HCC) and 35% in Maltoma. PET confirmed 39% CT detected lesions in RCC, 28% in HCC and 35% in Maltoma. PET missed 21% lesions that were detected by CT in RCC, 14% in HCC, and 28%in Maltoma. SUVmax of lesions could be calculated for 4 cases of RCC and 2 cases of HCC. The SUVmax was found to be in the range of 2.4 -16.95. This was found to be well above the cut off limit of 1.5gm/ml for low FDG concentrating lesions. Conclusion: This study confirms that 18F-FDG PET has a reasonable sensitivity in the detection of metastasis, although it is not sensitive enough to be the only modality for the evaluation of primary tumor and its metastasis. Our results suggest that it has a mutual complementary advantage, similar to the conclusion found previously in the detection of primary low FDG concentrating tumors. Although the SUV values remained well above the cutoff for the positive lesions, there was lack of sufficient data, including the factors affecting SUV, to substantiate it further including the lack of histopathological evidence of PET detected lesions for calculating true positive and true negative lesions.

Keywords: Low-FDG tumors, hepatoma, maltoma

PET 22 (POSTER)

Evaluation of diagnostic value of (18F)FDG-PET in patients of metastatic brain tumors

Mukta Joshi-Kulkarni, Basu S, Asopa R, Rajan MGR


Radiation Medicine Centre, Bhabha Atomic Research Centre, Parel, Mumbai - 400 012, India

Objective: The purpose of this study was to assess the role of (18F)FDG-PET in patients of metastatic brain tumors in the detection of occult primary and evaluating disease burden. Materials and Methods: (18F)FDG-PET studies, carried out in our Institute between May 2009-March 2010, in patients with radiologically and/or histopathologically proven brain metastases with occult primary were included in the study. Patients' records were retrospectively analyzed. According to the final pathological diagnoses, rate of detection of the primary tumor site was determined. The value of (18F)FDG-PET imaging was also evaluated as the first and only imaging modality in this clinical scenario in detecting the primary and assessing the overall disease burden. Results: Of the 25 cases, (18F)FDG -PET identified the primary tumor in 18 patients. Analysis 1; (18F)FDG-PET showed a sensitivity of 72% sensitive and accuracy of 76% in detection of primary lesions. Analysis 2: The most common primary origin of metastatic brain tumors in the patients studied was carcinoma of lung. (17/18 i.e. 94.4%) Analysis 3: As a single diagnostic modality (18F)FDG-PET defined whole body disease status and identified other metastatic sites than brain in 6 out of 18 patients (33%) Analysis 4: Only 1 patient showed no (18F)FDG uptake and no disease was identified further on any modality. (True Negative). Conclusion: (18F)FDG PET should be considered as first line investigation for diagnosing primary tumor in patients with metastatic brain tumor

Keywords: Brain metastases, FDG PET, unknown primary

PET 23 (POSTER)

Potential role of (18F)FDG PET imaging in defining tumor biology and monitoring therapeutic response in osteosarcoma - A retrospective study

Sonik Bhavay, Abhyankar A, Basu S, Rajan MGR, Asopa R


Radiation Medicine Centre, Bhabha Atomic Research Centre, Parel, Mumbai - 400 012, India

Introduction: The use of neo-adjuvant chemotherapy in the treatment of osteosarcoma has dramatically improved the survival rate in patients of osteosarcoma. Monitoring of preoperative chemotherapy response and estimating grade of tumor regression in patients with osteosarcoma is of pivotal importance before surgical removal of the tumor. The premise of the study was 18F-FDG whole body PET can be used to predict early the tumor response to chemotherapy and would help identifying unresponsive cases. Materials and Methods: A total of 64 patients were selected out of 100 patients who met the inclusion criteria. They were divided into two categories of pre-treatment (n=30) and post treatment (n=34) cases. The two categories were further split into two groups: Group I- with unknown metastasis before (18F)FDG PET scan and Group II- with known metastasis before (18F)FDG PET scan as per the conventional imaging modalities findings. (18F)FDG PET scan findings were compared with the conventional imaging modalities in each group of both categories and percentage of new, concurrent and lesions showing no uptake on PET as compared to the conventional imaging modalities was done. SUVmax of the primary site was calculated in the category of pretreatment cases and was used in predicting the tumor behaviour in the two groups made under this category after staging them in three ways: 1) As per the staging obtained from the conventional imaging modality data on presentation. 2) As per the revised staging done on PET scan findings. 3) As per the combined PET and conventional imaging modalities (CT/MRI). The pretreatment cases were classified as Stage I/II and Stage IV i.e. Stage I/II, when no metastasis present and Stage IV, when metastasis are present separately as per the three way staging system. Disease burden in pre-treatment cases was calculated by grouping the available data in three groups as: Group 1: Cases with primary tumor site only. Group 2: Cases with primary lesion and loco-regional metastasis - defined as marrow involvement and adjacent joint only. Group 3: Cases with primary lesion with distant metastasis. SUVmax and Avg. SUV of the primary site in pre and post neoadjuvant chemotherapy cases were calculated in 8 patients who had follow-up and histopathological reports were available for comparison. For a small subset of patients (n=11) in post treatment category SUVmax of the primary site was compared with the histopathological report available. Results: Mean SUVmax value in the primary lesion of the patients with distant metastasis was higher as compared to the patients without metastasis when staged as per PET or PET and conventional Radiology. This study also demonstrated that staging as well as restaging of the patient can be better done when PET is incorporated into the conventional staging system. No significant correlation between the% falls in Avg. SUV or SUVmax with the% necrosis as indicated on histopathology was obtained because of small patient number available. However, the visual assessment of the PET scan in both pre and post treatment cases showed response to the treatment and a trend was observed that more reduction suggesting greater necrosis in the tumor. Between two patients of pre and post chemotherapy whose survival data was available, low post SUVmax was associated with ≥ 90% necrosis on HPR and better survival rate (6 yrs alive v/s 2 yrs expired). The finding of correlation of low post treatment SUVmax and% necrosis was consistent with the findings mentioned in literature. Proper data of survival rate could not be obtained that could have been related to the various parameters in the study. Conclusions: The findings from this study provide evidence that amongst the patients with varying degree of disease burden at diagnosis, the FDG uptake in the primary lesion was higher in patient subgroup with distant metastasis as compared to those without metastasis or loco-regional metastasis. Thus SUVmax of the primary tumor may be directly correlated to the metastatic potential of the tumor. The study also emphasize on the need of the inclusion of PET in staging as well as restaging of the patients along with CT chest and MRI of the involved site. This helps not only in accurate staging but also helps in detecting new lesions by PET and detecting metabolically inactive lesions on PET. The study findings regarding assessment of response to chemotherapy by correlating% fall in Avg. SUV or SUVmax and% necrosis were statistically not significant but showed trend towards more reduction suggesting greater necrosis in the tumor whereas low post treatment SUVmax and ≥ 90% necrosis was consistent with the findings of the previous studies. Statistically significant result was not obtained which we believe was because of small patient number in each subgroup

Keywords: FDG PET, dual point imaging, lesion differentiation

PET 24 (ORAL)

Retrospective evaluation of the usefulness of dual Point (F-18)FDG-PET imaging

Joshi Prathamesh, Basu S, Asopa R


Radiation Medicine Centre, Bhabha Atomic Research Centre, c/o TMH Annexe, Parel, Mumbai - 400 012, India

Purpose: The purpose of this retrospective study was 1.To assess the role of 'Dual-point Imaging' in (F-18)FDG-PET in characterization of disease lesions 2. Quantitative and Qualitative analysis of (F-18)FDG-PET scan findings using Maximum Standardized Uptake Values (SUVmax) in various malignant and benign disorders. Materials and Methods: The patients who underwent (F-18)FDG-PET PET Scans with dual point imaging (between April 2009 to April 2010) were analysed in this retrospective study. The lesions which were included in both the set of images i.e. baseline and delayed views were evaluated. Semiquantitative analysis of (F-18)FDG uptake in the lesions in the baseline scan and delayed spot views was done using Maximum Standardized Uptake Value (SUVmax). The baseline value was noted as SUVmax1 and the delayed one as SUVmax2. A Retention Index (R.I) of FDG uptake was calculated by using formula- R.I. = (SUVmax2 - SUVmax1)/SUVmax1 To normalize the retention index with respect to time interval between baseline and delayed scan in various patients, a time corrected R.I. was calculated by dividing R.I. by time in hrs. Results: Of the 95 malignancy cases, 6 cases did not reveal the lesion in the delayed scan. In the remaining 89 cases of malignancy, the (F-18)FDG uptake in 169 lesions was studied in the baseline as well as delayed spot view. In the same way, its uptake in cases of infection and inflammation was studied. Analysis 1: The (F-18)FDG uptake in malignant lesions increased in the delayed scan as compared to baseline scan By using Pearson's correlation coefficient there was correlation between SUVmax1 and SUVmax2. SUVmax2 was more than SUV1 in the malignant lesions. The mean±S.D. for retention index (RI) and mean±S.D for Time corrected retention index (TCRI) was 0.309±0.756 and 0.169 ±0.480 respectively. Analysis 2: In the studied group, Out of different types of malignant lesions, the lesions of Non-Hodgkin's lymphoma showed he maximum retention of (F-18)FDG as evident by highest R.I. and T.C.R.I. (0.417±0.279 and 0.268±0.229 respectively) and Squamous cell carcinoma of lung showed the minimum retention shown by the least R.I. and T.C.R.I. (0.109±0.341 and 0.065±0.157 respectively) Analysis 3: The (F-18)FDG retention in the malignant lesions was higher as compared to lesions of infection and inflammation. However statistically the difference was not significant - P for RI 0.217(P>0.05) P value of TCRI is 0.73(P>0.05). Analysis 4: There was relatively low (F-18)FDG uptake (Mean SUVmax1: 2.7+0.32 gm/ml) in the lesions that completely disappeared in the delayed scan. Conclusion: There is an increase in the uptake of (F-18)FDG over time in the malignant lesions that is detected by dual-time-point PET. There is difference in the degree of uptake and retention of the tracer in the same types of malignancy. This may represent different mechanisms for uptake and retention at the cellular level. There was relatively low (F-18)FDG uptake in the lesions that completely disappeared in the delayed scan. A delayed scan in doubtful lesions with low FDG uptake may improve confidence in reporting

Keywords: FDG PET, dual point imaging, clinical utility

PET 25 (ORAL)

Role of 18F- FDG PET-CT in detection of primary tumors in carcinoma of unknown primary site: An Indian experience

Ramya S, Naswa N, Nazar AH, Patnecha M, Bangkimchandra KH, Bal CS, Bandohpadhyaya GP, Malhotra A, Kumar R


All India institute of medical sciences, New Delhi, India

The management of the patients with carcinoma of an unknown primary represents a difficult challenge in oncology. Metastatic cancers of unknown primary origin are characterised by a poor prognosis. Conventional radiological imaging allows only detection of 20%-27% of primary cancers. To evaluate the role of 18F-FDG PET/CT in detection of primary tumors in carcinoma of unknown primary site. Methods: In the present study, a total of 31 patients (22 males, 9 females; mean age 53.1 years) with biopsy or cytopathology proven metastatic carcinoma and negative conventional diagnostic procedures (CT, MRI or Panendoscopy) were included. All patients underwent whole body 18F-FDG PET/CT study. Patient data was retrospectively analysed. Histopathological diagnosis is kept as the gold standard. Hypermetabolic areas at the site of CT changes were considered as positive and rate of detection of primary site is evaluated. Among 31 patients, 18F-FDG PET/CT detected primary site in 14 patients. 18F-FDG PET/CT was negative in remaining 17 patients and could not localise primary. Among the 14 positive PET-CT patients, the results of 2 patients became false positive. The detection rate of 18F-FDG PET/CT in localising primary site was 38%. It is concluded that 18F-FDG PET/CT was found to be useful diagnostic procedure for the evaluation of patients with metastatic carcinoma and primary of unknown origin.

Keywords: Metastatic carcinoma, Detection of unknown primary, FDG PET

PET 26 (POSTER)

Potential role of 18 F-FDG PET in pre-op assessment and prognostication of pseudomyxoma peritonei

Khare Abhishek


Department of Nuclear Medicine, AH R and R, New Delhi - 10, India

The peritoneum is a serous lining of mesothelial cells with rich vascular and lymphatic capillary network that covers the abdominal and pelvic walls and organs. Peritoneal neoplasia can originate de novo from the peritoneal tissues (primary) or can spread into the peritoneum from adjacent or remote organs (secondary). Pseudomyxoma peritonei (PMP) is a rare condition characterized by large amounts of mucinous gelatinous deposition in the peritoneal cavity with or without demonstratable cancerous cells in the histopathological examination. It was first described by Rokitansky in 1842. It is a slow progressive process seen as extensive mucinous deposition within the abdominal and pelvic peritoneal cavity. PMP is a relatively rare pathology affecting 1 per million population, with an estimated incidence of 2 cases per 10,000 laparotomies.

Pseudomyxoma peritonei: Role of 18F-FDG PET in preoperative evaluation of pathological grade and potential for complete cytoreduction. This included 34 patients of PMP, who underwent pre-operative 18F-FDG PET scanning. They underwent a preoperative 18F-FDG PET with a double radiological evaluation and an explorative laparotomy with the objective of optimal cytoreduction followed by a hyperthermic intra-operative intraperitoneal chemotherapy (HIPEC). Patients with non resectable disease underwent debulking surgery without HIPEC. The Completeness of Cytoreduction was assessed by CC score. This study involved specialized teams for pathological grading of PMP.

Treatment: modalities depend on the histopathological grading and include debulking/cytoreductive surgery for more benign presentation and HIPEC(hyperthermic intra-operative chemotherapy) for more malignant conditions. Case Report: 58 years old female patient presented with history of insidious onset abdominal distension and pressure symptoms on the urinary tract manifesting as increased frequency of micturition for the past six months. CECT(Abdomen/pelvis) revealed gross ascitis, with conglomerate, lobulated mildly enhancing soft tissue mass measuring 5Χ11Χ6.5cm in retrosternal region extending both inside the supra and sub- diaphragmatic region (? Lymph nodal deposits). CT guided FNAC from sub diaphragmatic region revealed Mucinous material interspersed with scanty cells, a histopathological diagnosis of Pseudomyxoma peritonei grade II was established However Ascitic fluid examination for malignant cells was negative. The patient was referred to dept of PET/CT Army hospital RandR, for whole body PET/CT scan to know the extent of disease, with diagnosis of Carcinoma of unknown primary site (CUPS- Metastatic signet ring cell carcinoma) Whole body PET/ CT scan (base of skull to mid thigh) image acquisitions were performed with Siemens Biograph II Pet/CT, 45 minutes after i.v injection of 370 MBq of 18F- FDG, using a whole-body full-ring dedicated LSO PET/ CT scanner. CT images were obtained using 130KV and 90m As (mean) without administration of intravenous or oral contrast. CT based attenuation correction was done. Images were reconstructed using standard iterative algorithm (OSEM) and reformatted into Transaxial, Coronal and Sagittal views. A 3D image and fusion images of PET and CT were obtained. Physiological uptake of the tracer was noted in the brain, myocardium, liver, spleen, pelvicalyceal systems, urinary bladder and the gut. Increased FDG uptake was seen in mediastinal lymph nodes, left prevascular (SUV max-3.1) and large vascular nodes adjacent to SVC and ascending aorta (SUV max-3.4). Soft tissue density lesions were seen on Rt supradiaphragmatic (SUV max-2.8) and Lt Supradiagphragmatic region (between anterior chest wall and pericardium measuring approx 5.7Χ 9.4Χ2.8 cms, SUV max-3.1). Ascitis with mild-moderately increased FDG uptake in peritoneal collection was noted. FDG uptake over the circumference of fluid collection led to knobby outline with impression over the liver and spleen. The adnexal region and appendix were unremarkable. No other FDG avid lesions were detected in the scanned region of the body. FDG PET/ findings were suggestive of: mild-moderately FDG avid gross ascitis with mediastinal nodal involvement, along with FDG avid lesions in supradiaphragmatic regions(bilaterally). The findings were suggestive of grade II peritoneal mucinous carcinomatosis (intermediate hybrid form). The primary could not be ascertained. Unfortunately the patient declined available therapeutic options and was subsequently was lost to follow-up. 18F-FDG PET scan is a non-invasive modality, which by virtue of its whole body molecular imaging, could play a useful role in knowing the extent and pre-op assessment of this rare entity.

Keywords: Pseudomyxoma peritonei, peritoneal carcinomatosis, FDG PET




 

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