⁶⁸Ga-labeled prostate-specific membrane antigen (PSMA) ligand positron emission tomography/computed tomography imaging (PET/CT) is a rapidly evolving imaging modality for prostate cancer. Many studies have proved its superiority in staging, restaging, and detecting the recurrent prostate cancer. However, case reports describing the incidental tracer uptake in benign and nonprostatic malignancies are also reported in the literature, thus questioning the specificity of the tracer. This pictorial assay illustrates the nonspecific tracer uptake encountered during PSMA PET/CT imaging, knowledge of which can increase the confidence of interpreting physicians and may also open a new path for peptide receptor radionuclide therapy in nonprostatic malignancies.

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Neuroendocrine tumors (NETs) are rare neoplasms characterized by overexpression of somatostatin receptors (SSTRs). Functional imaging plays a crucial role in management of NETs. Recently, positron emission tomography/computed tomography (PET/CT) with ⁶⁸Gallium (⁶⁸Ga)-labeled somatostatin analogues has shown excellent results for imaging of NETs and better results than conventional SSTR scintigraphy. In this review we have discussed the utility of ⁶⁸ Ga-labeled somatostatin analogue PET/CT in NETs for various established and potential indications. In addition we have also shared our own experience from a tertiary care center in India.

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Introduction: ¹¹ C-methonine ([¹¹ C]-MET) positron emission tomography-computed tomography (PET-CT) is a well-established technique for evaluation of tumor for diagnosis and treatment planning in neurooncology. [ ¹¹ C]-MET reflects amino acid transport and has been shown to be more sensitive than magnetic resonance imaging (MRI) in stereotactic biopsy planning. This study compared fluorodeoxyglucose (FDG) PET-CT and MET PET-CT in the detection of various brain tumors. Materials and Methods: Sixty-four subjects of brain tumor treated by surgery, chemotherapy, and/or radiotherapy were subjected to [ ¹⁸ F]-FDG, [ ¹¹ C]-MET, and MRI scan. The lesion was analyzed semiquantitatively using tumor to normal contralateral ratio. The diagnosis was confirmed by surgery, stereotactic biopsy, clinical follow-up, MRI, or CT scans. Results: Tumor recurrence was found in 5 out of 22 patients on [F-18] FDG scan while [ ¹¹ C]-MET was able to detect recurrence in 18 out of 22 patients in low-grade gliomas. Two of these patients were false positive for the presence of recurrence of tumor and later found to be harboring necrosis. Among oligodendroglioma, medulloblastoma and high-grade glioma out of 42 patients 39 were found to be concordant MET and FDG scans. On semiquantitative analysis, mean T/NT ratio was found to be 2.96 ± 0.94 for lesions positive for recurrence of tumors and 1.18 ± 0.74 for lesions negative for recurrence of tumor on [ ¹¹ C]-MET scan. While the ratio for FDG scan on semiquantitative analysis was found to be 2.05 ± 1.04 for lesions positive for recurrence of tumors and 0.52 ± 0.15 for lesions negative for recurrence of tumors. Conclusion: The study highlight that [ ¹¹ C]-MET is superior to [ ¹⁸ F]-FDG PET scans to detect recurrence in low-grade glioma. A cut-off value of target to nontarget value of 1.47 is a useful parameter to distinguish benign from malignant lesion on an [ ¹¹ C]-MET Scan. Both [ ¹⁸ F]-FDG and [ ¹¹ C]-MET scans were found to be useful in high-grade astrocytoma, oligodendroglioma, and medulloblastoma.

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Background : In medical applications of radioisotopes, for calculations of whole body doses and radiation safety applications, there is a need to estimate radioactive body burden. Local recommendations in Oman stipulate the need for hospitalization of patients treated for radioactive-iodine ( ¹³¹ I) with activities above 400 MBq. Materials & Methods: A study of body burden estimation from sequentially measured exposure rates from patients treated for carcinoma thyroid and hyperthyroidism was undertaken. A digital auto-ranging beta gamma survey instrument calibrated for measurement of exposure rates is used in this study. Results: The mean measured exposure rates at 1 m in μSv/h immediately after administration and at 24 h intervals are used for estimation of effective half time of clearance of administered activity. For patients with post-operative thyroid carcinoma, the variation of body burden with time post-administration indicated tri-exponential clearance pattern, with T_½eff values 14.4 h, 22 h, and 41.3 h. For patients treated for thyrotoxicosis, the body burden showed slow delayed clearance with a T_½eff - 111.4 h, and exposure rates did not show appreciable fall off after 48 h.

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Purpose: Review published studies to investigate the value of clinical 3-deoxy-3- ¹⁸ F-fluorothymidine (FLT) positron emission tomography (PET) in predicting response to treatment. Materials and Methods: Interrogate databases to identify suitable publications between 2007 and 2013 with a minimum of five patients. Articles within the inclusion criteria were reviewed with major findings reported leading to a descriptive analysis of FLT PET in therapy response. Results: Lesions investigated included glioma, head and neck, esophageal, lung, breast, gastric, renal, rectal, sarcomas, germ cell, lymphomas, leukemia, and melanoma resulting in a total of 34 studies analyzed. A variety of therapies were applied and dissimilar PET protocols were widespread making direct comparison between studies challenging. Though baseline, early and late therapy scans were popular particularly in chemotherapy regimes. Most studies investigated showed significantly reduced FLT uptake during or after therapy compared with pretreatment scans. Conclusion: Current evidence suggests FLT PET has a positive role to play in predicting therapy response especially in brain, lung, and breast cancers where good correlation with Ki-67 is observed. However, careful attention must be placed in undertaking larger clinical trials where harmonization of scanning and analysis protocols are strictly adhered to fully assess the true potential of FLT PET in predicting response to treatment.

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Diaschisis is the inhibition of function produced by focal disturbances in a portion of the brain at a distance from original site of injury. Many studies using brain SPECT (single-photon emission computed tomography) have demonstrated crossed cerebellar diaschisis (CCD) in patients with cerebral cortical infarct. We report a case of cerebrovascular accident involving the left middle cerebral artery territory. PET/CT performed one month after stroke showed hypometabolism in the left cerebral hemisphere with hypometabolism of the contralateral cerebellum. The finding of diminished glucose metabolism in the contralateral cerebellum represents CCD.

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Prostate cancer is the second most common cancer in man. It commonly presents with urinary symptoms, bone pain, or diagnosed with elevated prostate-specific antigen.(PSA) levels. Correct staging and early diagnosis of recurrence by a precise imaging tool are the keys for optimum management. Molecular imaging of prostate cancer with Ga-68 prostate-specific membrane antigen.(PSMA), positron emission tomography-computed tomography.(PET-CT) has recently received significant attention and frequently used with a signature to prostate cancer-specific remark. However, this case will highlight the more cautious use of it. A-72-year-old male treated earlier for synchronous double malignancy.(invasive papillary urothelial carcinoma right ureter and carcinoma prostate) presented with rising PSA.(0.51.ng/ml) and referred for Ga-68 PSMA PET-CT, which showed a positive enlarged left supraclavicular lymph node. Lymph node biopsy microscopic and immunohistochemistry examination revealed metastatic carcinoma favoring urothelial origin. Specificity of PSMA scan to prostate cancer has been seen to be compromised in a certain situation mostly due to neoangiogenesis, and false positives emerged in renal cell cancer, differentiated thyroid cancer, glioblastoma, breast cancer brain metastasis, and paravertebral schwannomas. Understanding the causes of false positive will further enhance the confidence of interpretating PSMA scans.

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Background: Prostate cancer is biologically and clinically a heterogeneous disease that makes imaging evaluation challenging. One of the important challenges in this cancer is to detect recurrent disease. Biochemical response using Prostate Specific Antigen (PSA) and Imaging using several PET tracers have poor sensitivity and specificity. Therefore, we analyse the role of Ga68-PSMA (Prostate Specific Membrane Antigen) imaging in prostate cancer, which is a new PET tracer. Methods: In this study, we evaluated PET scans of 262 patients with diagnosis of prostate cancer. These patients were scanned using Ga68-PSMA for either staging or response evaluation. Results: 336 PSMA scans were performed. Ga68-PSMA scan resulted in the detection of extra-prostatic disease in 53.2% of cases when done at baseline before commencing any treatment. The sensitivity of Ga68-PSMA at baseline with histopathological diagnosis was 95% with 95% CI ranging from 86% to 98%. The positive predictive value was high at 98% with 95% CI ranging from 91% to 99%. In 26 (10%) patients who had surgical castration, Ga68-PSMA scan was able to detect disease progression / castration resistance in 100% of cases. The outcome of castration-resistant prostate cancer was compared with other cases where castration was not done. In those who did not undergo castration, there was a significantly better response by hormone therapy (p = 0.03) and radiotherapy (p = 0.01) on Ga68-PSMA. The sensitivity of Ga68-PSMA response with biochemical response was 66.7% with 95% CI ranging between 46 %- 82.7%. Ga68-PSMA response did not correlate with biochemical response. Conclusion: Ga68-PSMA has good sensitivity for diagnosis, staging, restaging, evaluation of therapy response and prognostication in prostate cancer.

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Objective : To measure the radiation exposure to nuclear medicine personnel during synthesis and injection to the patients of Ga-68 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-1-Nal ³ -octreotide (NOC)- (DOTA-NOC) using ring thermoluminescence dosimeters (TLDs). Materials and Methods : Synthesis of Ga-68 DOTA-NOC was done on a semi-automated system. Finger doses were measured during synthesis and injection of Ga-68 DOTA-NOC. The occupational workers wore TLDs at the base of ring finger of both hands. The finger doses of two radio chemists were measured during synthesis of Ga-68 DOTA-NOC while that of a physician during its injection to the patients. Results : Duration of the study was eight months and a total of 20 samples were prepared. During synthesis, the mean dose to base of left ring finger was 3.02 ± 1.01 mSv and to base of right ring finger was 1.96 ± 0.86 mSv. Mean dose to base of left ring finger was 1.26 ± 0.35 mSv while that to base of right ring finger was 1.03 ± 0.13 mSv during injection. The mean dose was observed to be higher during synthesis than injection. However, the difference was not significant (P = 0.27 and P = 0.18, respectively). Overall mean finger dose of left hand was 2.43 ± 1.21 mSv, whereas for the right hand the same was 1.65± 0.82 mSv. Conclusion : Finger doses to radio chemists during semi-automated synthesis of Ga-68 DOTA-NOC and that to the physician involved in injection of Ga-68 DOTA-NOC were found to be within permissible limits. Ring dosimeters must be worn for the safety of the nuclear medicine personnel involved in synthesis and injection of Ga-68 DOTA-NOC.

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Background: Skull base osteomyelitis (SBO) refers to infection that has spread beyond the external auditory canal to the base of the skull in advanced stages of otitis externa. Clinically, it may be difficult to differentiate SBO from severe otitis externa without bony involvement. This study was performed to determine the role of three phase bone scintigraphy (TPBS) and single photon emission tomography/computed tomography (SPECT/CT) in detecting SBO. Materials and Methods: We retrospectively analyzed records of 20 patients (14 M, 6 F) with otitis externa and suspected SBO. TPBS and SPECT/CT of the skull were performed. Findings were correlated with clinical, laboratory and diagnostic CT scan findings. Results: All patients were diabetic with elevated erythrocyte sedimentation rate. A total of 18 patients had bilateral and two unilateral symptoms. Cranial nerves were involved in eight patients and microbiological culture of ear discharge fluid positive in seven. Early images showed increased temporal vascularity in nine patients and increased soft-tissue uptake in 10, while delayed images showed increased bone uptake in 19/20 patients. Localized abnormal tracer uptake was shown by SPECT/CT in the mastoid temporal (15), petrous (11), sphenoid (3) and zygomatic (1) and showed destructive changes in five. Thus, TPBS was found positive for SBO in 10/20 patients and changed the management in four. Conclusion: Our study suggests that TPBS with SPECT/CT is a useful non-invasive investigation for detection of SBO in otitis externa.

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Brain single photon emission computed tomography (SPECT) is a well-established and reliable method to assess brain function through measurement of regional cerebral blood flow (rCBF). It can be used to define a patient's pathophysiological status when neurological or psychiatric symptoms cannot be explained by anatomical neuroimaging findings. Though there is ample evidence validating brain SPECT as a technique to track human behavior and correlating psychiatric disorders with dysfunction of specific brain regions, only few psychiatrists have adopted brain SPECT in routine clinical practice. It can be utilized to evaluate the involvement of brain regions in a particular patient, to individualize treatment on basis of SPECT findings, to monitor the treatment response and modify treatment, if necessary. In this article, we have reviewed the available studies in this regard from existing literature and tried to present the evidence for establishing the clinical role of brain SPECT in major psychiatric illnesses.

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Osteopetrosis is a rare inherited bone disease where bones harden and become abnormally dense. While the diagnosis is clinical, it also greatly relies on appearance of the skeleton radiographically. X-ray, radionuclide bone scintigraphy and magnetic resonance imaging have been reported to identify characteristics of osteopetrosis. We present an interesting case of a 59-year-old man with a history of bilateral hip fractures. He underwent ^99m Tc-methylene diphosphonate whole body scan supplemented with single-photon emission computed tomography/computed tomography of spine, which showed increased uptake in the humeri, tibiae and femora, which were in keeping with osteopetrosis.

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Purpose of the Study: Rutin (RUT) and quercetin (QRT) which are dietary compounds were investigated for their ability to protect against ionizing radiation (IR)-induced genotoxicity in human lymphocytes. Materials and Methods: The radiation antagonistic potential of RUT and QRT was assessed by alkaline comet and cytokinesis-block micronucleus (CBMN) assay. Results: Treatment of lymphocytes with RUT and QRT (25 μg/ml) prior exposure to 2 Gy gamma radiation resulted in a significant reduction of frequency of micronuclei as compared to the control set of cells evaluated by CBMN assay. Similarly, treatment of lymphocytes with RUT and QRT before radiation exposure showed significant decrease in the DNA damage as assessed by comet parameters, such as percent tail DNA and olive tail moment. Conclusion: The study demonstrates the protective effect of RUT and QRT against IR-induced DNA damage in human lymphocytes, which may be partly attributed to scavenging of IR-induced free radicals and also by the inhibition of IR-induced oxidative stress.

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We report a rare case of leiomyosarcoma of the inferior vena cava (IVC) in which F-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography-computed tomography (PET-CT) scan provided vital evidence, which led to its diagnosis, in a background of procoagulant state of the patient, where previous ultrasound-Doppler and echocardiography studies were nonspecific and revealed bilateral lower limb deep vein thrombosis with thrombus in IVC. The whole body F-18 FDG PET-CT scan was done in view of no significant improvement in clinical status of the patient over few months in spite of appropriate medical management. FDG PET-CT scan revealed high grade uptake in a large mass lesion occupying the right atrium, extending superiorly into terminal superior vena cava, inferiorly into dilated IVC and probably into hepatic veins. CT guided biopsy of this F-18 FDG avid mass was consistent with the diagnosis of leiomyosarcoma, which however was not amenable to surgery at this stage. F-18 FDG PET-CT accurately differentiated tumor mass from bland thrombus and further had a significant impact on the management, since aggressive surgery combined with adjuvant therapy offers the best outcome for patients with leiomyosarcoma of the IVC.

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Background: This paper is based on the initial findings from a prospective ongoing study to evaluate the efficacy of flourodeoxy glucose positron emission tomography-computed tomography (FDG-PET CT) in diabetic foot evaluation. Objective: The aim was to compare the diagnostic accuracies of three phase bone scan (TPBS) and FDG PET-CT (FDG-PET) in diabetic foot evaluation. Methods: Seventy-nine patients with complicated diabetic foot (osteomyelitis/cellulitis, Charcot's neuropathy) were prospectively investigated. TPBS (15 mci methylene di phosphonate [MDP] intravenous [IV]), followed by FDG-PET (5 mci IV) within 5 days were performed in all patients. Based on referral indication, patients grouped into Group I, n = 36, (?osteomyelitis/cellulitis) and Group II, n = 43 (?Charcot's neuropathy). Interpretation was based on intensity, extent, pattern of MDP and FDG uptake (standardized uptake value) along with CT correlation. Findings were compared with final diagnostic outcome based on bone/soft tissue culture in Group I and clinical, radiological or scintigraphic followup in Group II. Results: Group I: For diagnosing osteomyelitis, TP: TN: FP: FN were 14:5:2:2 by FDG PET and 13:02:05:03 by TPBS respectively. Sensitivity, specificity, positive predictive value and negative predictive value (NPV) of FDG-PET were 87.5%, 71%, 87.5% and 71% and 81.25%, 28.5%, 72% and 40% for TPBS, respectively. Group II: charcot's: cellulitis: Normal were 22:14:7 by FDG PET and 32:5:6 by TPBS, respectively. Conclusion: Flourodeoxy glucose PET-CT has a higher specificity and NPV than TPBS in diagnosing pedal osteomyelitis. TPBS, being highly sensitive is more useful than FDG-PET in detecting Charcot's neuropathy.

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Purpose of the Study: The present study was undertaken to evaluate the diagnostic utility of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) in patients presenting as pyrexia of unknown origin (PUO). Materials and Methods: Forty-seven patients (31 males and 16 females; mean age of 42.7 ± 19.96 years) presenting as PUO to the Department of Medicine at the All India Institute of Medical Sciences, New Delhi over a period of 2 years underwent F-18 FDG PET/CT. PET ⁄ CT was considered supportive when its results correlated with the final definitive diagnosis. Final diagnosis was made on the basis of combined evaluation of history, clinical findings, investigations, and response to treatment. Results: Thirty-five PET/CT studies (74.5%) were positive. However, only 18 (38.3%) were supportive of the final diagnosis. In three patients (6.4%), PET/CT was considered diagnostic as none of the other investigations including contrast-enhanced computed tomography of chest and abdomen, and directed tissue sampling could lead to the final diagnosis. All these three patients were diagnosed as aortoarteritis. Conclusion: Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography is an important emerging modality in the workup of PUO. It supported the final diagnosis in 38% of our patients and was diagnostic in 6.4% of patients. Thus, PET/CT should only be considered as second-line investigation for the diagnostic evaluation of PUO; especially in suspected noninfectious inflammatory disorders.

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Purpose: Estimation of Compton attenuation and the photoelectric absorption coefficients were explored at various depths. Methods: A new method was proposed for estimating the depth based on the convolution of two exponential functions, namely convolution of scattering and primary functions (CSPF), which the convolved result will conform to the photopeak region of energy spectrum with the variable energy-window widths (EWWs) and a theory on the scattering cross-section. The triple energy-windows (TEW) and extended triple energy-windows scatter correction (ETEW) methods were used to estimate the scattered and primary photons according to the energy spectra at various depths due to a better performance than the other methods in nuclear medicine. For this purpose, the energy spectra were employed, and a distinct phantom along with a technetium-99 m source was simulated by Monte Carlo method. Results: The simulated results indicate that the EWW, used to calculate the scattered and primary counts in terms of the integral operators on the functions, was proportional to the depth as an exponential function. The depth will be calculated by the combination of either TEW or ETEW and proposed method resulting in the distinct energy-window. The EWWs for primary photons were in good agreement with those of scattered photons at the same as depths. The average errors between these windows for both methods TEW, and ETEW were 7.25% and 6.03% at different depths, respectively. The EWW value for functions of scattered and primary photons was reduced by increasing the depth in the CSPF method. Conclusions: This coefficient may be an index for the scattering cross-section.

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Purpose: ¹⁸F-Fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) is now recognized as a staging investigation for locally advanced breast cancer. This retrospective review of data was performed to correlate the maximum standardized uptake value (SUV_max) of the primary tumor with the molecular subtype of breast cancer. Materials and Methods: Patients with biopsy-proven, treatment naïve, Stage III breast cancer, for whom ¹⁸F-FDG PET/CT data and immunohistochemistry 4 was available were included in the study. Correlations were deduced between the SUV_max of primary tumor to the molecular subtypes. Results: Three hundred and two patients were included in the study. Fifty-two (17.2%) tumors were Luminal A (LA), 131 (43.4%) Luminal B (LB), 42 (13.9%) human epidermal growth factor receptor-2 enriched (HE), and 77 (25.5%) basal-like (BL). SUV_max of the primary tumor differed significantly between LA and other subtypes (SUV_max: LA Median 7.4, LB 11.65, HE 13.5, BL 15.35, P < 0.001). Estrogen receptor (ER) and progesterone receptor (PR) positivity were inversely correlated to the SUV_max of the primary (SUV_max: ER + Median 10.4, ER - 14.2, P < 0.001, PR + 9.65, PR − 13.9, P < 0.001). There was a strong positive correlation observed between Ki67 and SUV_max (Pearson Coefficient 0.408, P < 0.001). A SUV_max value of 9.65 was determined as a cutoff on receiver operating characteristic curve to differentiate between LA and other subtypes with a sensitivity of 92.3% and specificity of 70.6%. Conclusions: SUV_max of primary showed a statistically significant difference between LA subtypes when compared to other subtypes. However, there was overlap of values in each subgroup and thus ¹⁸F-FDG PET/CT cannot be used to accurately assess the molecular characteristics of the tumor.

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Aim: To determine whether F-18-fluorodeoxyglucose positron emission tomography (F-18-FDG PET) can be used to differentiate among common enhancing brain tumors such as gliomas, metastatic brain tumors, and lymphoma. Materials and Methods: We evaluated 20 patients with an enhancing brain tumor on magnetic resonance imaging (MRI). FDG PET scan was done in all patients pre operatively. For PET image analysis, regions of interest were placed over the tumor (T), contralateral cortex (C), and white matter (WM). Average and maximum pixel values were determined at each site. On the basis of these measurements, average and maximum standard uptake values (SUV _avg and SUV _max ) were calculated, and comparisons among lesions were then made. Results: SUV _avg and SUV _max are significantly higher for central nervous system (CNS) lymphoma than for other tumors ( P < 0.01). High-grade gliomas showed significantly higher SUV _avg and SUV _max than the low grade gliomas ( P < 0.05) and metastatic tumor showed higher SUV _avg and SUV _max than all gliomas, both low and high grade ( P < 0.05). When the lowest values of CNS lymphoma parameter were used as cutoff levels to distinguish CNS lymphomas from other tumors (i.e. 100% sensitivity), SUV _max was the most accurate parameter. Using a SUV _max of 15.0 as a cutoff for diagnosing CNS lymphoma, only one case of metastasis (SUV _max , 16.3) was found to be false positive in this study. Conclusion: FDG PET appears to provide additional information for differentiating common enhancing malignant brain tumors, namely lymphoma versus high grade glioma and metastatic tumor, particularly when differential diagnoses are difficult to narrow using MRI alone.

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Context: Radiation therapy is the prime treatment modality against various cancers. However, its use is limited due to the effects of radiation on normal tissues. Aims: In view of this, present study was carried out to evaluate the radioprotective potential of Rutin (RUT) and Quercetin (QRT) in Swiss Albino mice exposed to the whole body gamma radiation. To gain insight into the mechanism of action, RUT and QRT were tested for its antioxidant levels in mice. Settings and Designs: Optimum protective dose of RUT and QRT against radiation induced animal mortality was selected by administration of various doses of the RUT and QRT before 10 Gy gamma irradiation. Materials and Methods: Swiss Albino mice were used for the assessment of radiation induced sickness along with the survival analysis and anti-oxidative properties of RUT and QRT. Statistical Analysis Used: Survival studies were determined using the Kaplan-Meier survival curves. Results: The maximum survival was observed with 10 mg/kg. b. wt. and 20 mg/kg. b. wt. of RUT and QRT respectively, this dose was considered as an optimal dose for radioprotection. Treatment of mice with RUT and QRT before irradiation delayed the onset of mortality as compared with the untreated irradiated controls. The oral administration of RUT and QRT resulted in an increase in the radiation tolerance and the dose reduction factor was found to be 1.15 and 1.11 respectively. RUT and QRT pre-treatment significantly (P < 0.01) elevated levels of reduced glutathione, glutathione-S-transferase, catalase, Superoxide dismutase, and a decreased lipid peroxidation in mouse liver homogenate at 24 h after exposure to 4.5 Gy. Conclusions: Present findings demonstrate the potential of RUT and QRT in mitigating radiation-induced mortality, which may be attributed to the elevation in the antioxidant status, anti-lipid peroxidative potential.

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Aim: The aim of this study is to evaluate the role of ⁶⁸ Ga-DOTATATE positron emission tomography/computed tomography (PET/CT) scan for the detection of bone metastases in pediatric neuroendocrine tumors (NETs) and to compare it with CT scan. Materials and Methods: A total of 30 patients (18 were males and 12 were females; age range: 1-18 years; mean age 7.6 years) with histologically confirmed NETs referred to our department were retrospectively analyzed. All patients underwent ⁶⁸ Ga-DOTATATE PET/CT scan at the time of diagnosis for primary staging. Contrast enhanced CT (CECT) performed at the time of PET scan acquisition was used for comparison with PET data. Imaging results were analyzed on a per-patient and on a per-lesion basis. Clinical follow-up of all patients and repeat PET/CT imaging ( n = 10) was taken as the reference standard. Results: Out of the 30 patients, 17 had no evidence of bone metastases on any imaging modality or on clinical follow-up while the rest of 13 patients showed evidence of bone metastases (nine showing positivity both on ⁶⁸ Ga-DOTATATE PET and CT scan while four showing positivity only on ⁶⁸ Ga-DOTATATE PET). Compared with CT scan, ⁶⁸ Ga-DOTATATE PET detected bone metastases at a significantly higher rate ( P = 0.0039). On a per lesion analysis, out of a total of 225 lesions detected by ⁶⁸ Ga-DOTATATE PET, only 84 lesions could be detected by CT scan. Conclusion: ⁶⁸ Ga-DOTATATE PET/CT scan is more useful than CECT scan for the early detection of bone metastases in pediatric NETs.

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Cardiac angiosarcoma is the most common primary cardiac sarcoma in adults. Primary cardiac tumors are rare and have nonspecific clinical presentation, thus making its diagnosis challenging. Clinically, patients present with advanced disease demonstrating metastatic disease at initial presentation itself. It commonly metastasizes to lung, liver, brain, and bone; however metastases to lymph nodes, adrenal glands, spleen and skin has also been seen. We describe a case of right atrial angiosarcoma with extensive visceral metastases involving brain, lungs, liver, pancreas, kidney, and lymph nodes, demonstrated on contrast-enhanced ¹⁸ F-fluoro-deoxyglucose positron emission tomography-computed tomography (FDG PET-CT). To the best of our knowledge metastases to pancreas and kidney have not been reported so far in the literature. With our report, we emphasize on the initial use of FDG PET-CT in workup of cardiac angiosarcoma for accurate staging and prognostication of this disease.

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Objectives: Assess the added value of dual time point F-18-fluorodeoxyglucose positron emission tomography/computed tomography (DTP F-18-FDG-PET/CT) in the differentiation of malignant from a benign lesion in cancer patients. Materials and Methods: Totally, 140 F-18-FDG PET/CT scans of 60 cancer patients who underwent DTP protocol (early whole body PET/CT [E] at 60 min [range, 45-76 min] and delayed limited PET/CT [D] on areas of interest at 120 min [range, 108-153 min] after the tracer injection) were retrospectively reviewed. Visual and semi-quantitative analysis was performed on both early and delayed images. All findings were confirmed by histopathology and/or at least 3 months follow-up (F-18-FDG PET/CT, CT, or magnetic resonance imaging). The result was considered true positive (TP) if delayed standardized uptake value (SUV) of suspicious lesions increased and confirmed to be malignant, false positive (FP) if delayed SUV increased and confirmed to be benign, true negative (TN) if delayed SUV unchanged or decreased and confirmed to be benign, and false negative (FN) if delayed SUV unchanged or decreased and confirmed to be malignant. Results: A total of 164 suspicious lesions were detected (20 presacral lesions, 18 lung nodules, 18 Hodgkin's disease (HD) lesions, 16 rectal lesions, 16 head and neck (H and N) lesions, 14 hepatic lesions, 14 non-Hodgkin's lymphoma (NHL) lesions, 12 mediastinal lymph nodes (LNs), 10 focal gastric uptake, 10 soft tissue lesions, 8 breast lesions, 4 peritoneal nodule, and 4 others). Sixty-four lesions were pathologically confirmed, and 100 lesions were confirmed based on 3-6 months follow-up. There were 62 TP lesions, 44 FP, 58 TN and no FN results. The overall sensitivity was 100% of DTP F-18-FDG PET/CT in detecting suspicious lesions. The specificity was 57% in differentiating malignant from benign lesions, and the accuracy was 73%. Positive predictive value was 59%, negative predictive value (NPV) 100%. All hepatic lesions were TP. Accuracy in metastatic hepatic lesions HD, presacral soft tissue, lung nodules, H, and N cancer, breast cancer, NHL and mediastinal LN was100%, 88.8%, 80%, 78%, 75%, 75%, 71%, and 33.3%, respectively. Conclusions: DTP F-18-FDG-PET/CT protocol does not always work in differentiation between benign and malignant lesions. However; it has high NPV, and promising results was noted in hepatic lesions, lymphoma, and recurrent rectal cancer.

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Purpose of the Study: Standardized uptake value (SUV) is the most commonly used semi-quantitative PET parameter. Various response assessment criteria grade the tumor uptake relative to liver or mediastinal uptake. However various factors can affect the background SUV values. This prospective study was carried out to assess the variability of liver and mediastinal SUVs normalized to lean body mass (SUL-L, SUL-M), body surface area (SUB-L, SUB-M), and body weight (SUW-L, SUW-M) and their dependence on various factors which can affect SUV values. Materials and Methods: Eighty-eight patients who underwent F-18 FDG PET/CT for various oncological indications were prospectively included in this study. SUVs of liver and mediastinum were calculated by ROIs drawn as suggested by Wahl, et al., in PERCIST 1.0 criteria. Multivariate linear regression analysis was done to assess for the various factors influencing the SUVs of liver and mediastinum. Factors assessed were age, sex, weight, blood glucose level, diabetic status, and uptake period. A P value less than 0.01 was considered significant. Results: SUL-L, SUL-M, SUB-L, SUB-M, SUW-L, SUW-M were not affected significantly by age, sex, blood glucose levels, diabetic status. The uptake period had a statistically significant effect on SUL-L ( P = 0.007) and SUW-L ( P = 0.008) with a progressive decrease with increasing uptake time. Body weight showed a statistically significant effect on SUW-L ( P = 0.001) while SUL-L and SUB-L were not dependent on weight. SUB-L was least dependent on weight ( P = 0.851) when compared with SUL-L ( P = 0.425). However SUL-L was also not affected statistically significantly by variations in body weight ( P = 0.425). Mediastinal SUVs were not significantly affected by any of the factors. Conclusions: As mediastinal SUVs are not affected significantly by any of the factors, it can be considered as background when wide variations occur in uptake times or weight of the patient when comparing two PET/CT studies to evaluate response.

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Introduction: Although single-photon emission computed tomography (SPECT)/computed tomography (CT) plays a major role in the characterization of equivocal lesions on bone scintigraphy, it remains equivocal in a fraction of these patients. We evaluated the additional value of cocktail F-18 sodium fluoride (18F-NaF) and F-18 fluorodeoxyglucose (18F-FDG) co-injection positron emission tomography (PET) (cocktail PET) in these patients. Materials and Methods: Fifteen breast cancer patients, who had equivocal findings on the whole body bone scan (WBS) and SPECT/CT, were subjected to a cocktail PET/CT scan. The cocktail PET/CT was performed by co-administration of 18F-FDG and 18F-NaF in a ratio of about 2.4, with the total administered activity kept at approximately 10 mCi. Results: Of the 15 patients, seven were with locally advanced breast cancer (LABC) and the other eight were referred because of suspicion of recurrent disease on follow-up. Of the seven patients with LABC, the cocktail PET scan was positive for all the lesions suspicious on WBS and SPECT/CT. Additionally, it showed uptake in the primary tumor and ipsilateral axillary lymph nodes as well as identified additional osseous, lymph nodal, and solid organ metastases in these patients. Similarly, of the eight patients studied for suspicion of recurrence, the cocktail PET scan was found to be positive in seven patients. In three patients, additional osseous lesions were noted. Conclusion: The cocktail PET/CT scan can characterize almost all the suspicious equivocal lesions on the bone scan and SPECT/CT. The distinct advantage of identifying lymph nodal and solid organ metastases allows it to be considered as a useful imaging modality in patients with equivocal bone SPECT/CT.

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