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ABSTRACT
Year : 2010  |  Volume : 25  |  Issue : 3  |  Page : 98-102 Table of Contents   

Thyroid


Date of Web Publication25-Nov-2010

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How to cite this article:
. Thyroid. Indian J Nucl Med 2010;25:98-102

How to cite this URL:
. Thyroid. Indian J Nucl Med [serial online] 2010 [cited 2019 Jul 19];25:98-102. Available from: http://www.ijnm.in/text.asp?2010/25/3/98/72759

THY 01 (ORAL)

Incremental value of 131 I-SPECT/CT study in evaluation of patients with differentiated thyroid cancers

Kumar Abhishek, Bal CS, Damle N, Kundu P, Maharjan S, Naswa N, Malhotra A, Bandopadhyaya GP


Department of Nuclear Medicine, AIIMS, New Delhi, India

131 I planar scintigraphy has been the conventional modality for identifying residual and metastatic disease in patients with differentiated thyroid cancers. With the avaibility of SPECT/CT it would be imperative to evaluate if 131 I-SPECT/CT may have an additional value over planar imaging. The aim of the present study was to investigate whether 131 I-SPECT/CT has any incremental value over planar scan in identifying remnant disease, local and distant metastases and its impact on therapeutic management. Planar and SPECT/CT imaging of 48 post thyroidectomy patients were retrospectively analyzed. The planar and SPECT/CT imaging included diagnostic and post therapeutic scans. Whenever SPECT/CT identified iodine uptake foci to a more correct anatomic localization and/or precisely demarcated the tumor from physiological areas of radiotracer uptake, an incremental value was assigned. Overall, SPECT/CT detected more definitive foci than planar in 13% of patients. SPECT/CT had an incremental value in 38% of patients. SPECT/CT modified therapeutic management in 23% of positive cases which included adjustment of 131 I therapeutic dose, need for repeat surgery and avoidance of unnecessary radio-iodine treatment.

Keywords: Solid state detector cardiac camera, diastolic dysfunction, myocardial perfusion imaging, time to peak filling (TTPF)

THY 02 (POSTER)

A rare case of metastatic thyroid carcinoma presenting as primary renal neoplasm

Wing Cdr Dash AK, Col Ravikumar R, SurgCdr Gill BS


INHS Asvini, Mumbai, India

Thyroid cancer is one of the common neoplasms accounting for 2% of all diagnosed neoplasms. Papillary carcinoma, If diagnosed and treated with radio iodine after thyroidectomy well in time, offers excellent survival benefit. Role of Radio iodine Whole body scan is crucial in these cases in detecting focal lesions and metastases. Common sites of metastases include cervical LN, trachea, esophagus, lungs, bones and brain. Metastases to kidneys are very rare and reported in very few cases. Our case is a 72 yrs old mother of serving soldier, a known case of CAD, DM, and HTN admitted with insidious onset right flank abdominal pain. Clinical examination revealed BP of 170/100mmHg, no pallor, edema or puffiness. Abdomen examination revealed mild tenderness in the right renal angle. There was no free fluid or organomegaly.Subsequent evaluation with USG was inclusive.MRI abdomen revealed a mass lesion involving lower pole and distorting intra renal structures. The lesion was seen extending in to right renal artery. A diagnosis of Renal Cell Carcinoma (RCC) was made. She underwent right radical nephrectomy. Biopsy of post operative specimen revealed surprising histo pathological features of metastatic Papillary carcinoma of thyroid. She underwent a total thyroidectomy and thyroid specimen confirmed follicular variant of Papillary Carcinoma Thyroid in the setting of multiple hypoechoic nodules. She had a markedly elevated Serum Thyroglobulin of 2118.0 ng/ml.Post operative 131 I Whole Body Scan revealed residual functional thyroid with skeletal metastases. She was given high dose radio iodine ablation with 218 mCi.She was reviewed twice subsequently in Feb 2009 and Aug 2009. She was given 221 mCi of 131 I ablation given for solitary residual bone mets with raised Tg (345ng/ml) while Aug 2009 WB Scan was normal along with normal serum Tg (2.1 ng/ml).This case describes an unusual case of elderly lady with FVPTC presenting as renal mass suspected to be a case of RCC with extension in to renal vein which would have carried worst prognosis as compared to thyroid carcinoma which was successfully made disease free over last two years. Treatment of kidney mass led to the discovery of primary thyroid neoplasm and its specific treatment. This also highlights importance of structural imaging such as USG,CT & MRI and subsequent histopathological confirmation.

Keywords: Thyroid carcinoma, radioiodine scan, renal metastases

THY 03 (POSTER)

Role of diagnostic 131 Iodine SPECT-CT in guiding radioiodine ablation therapy in patients with differentiated thyroid cancer

Kuruva Manohar, Kashyap R, Kamaleshwaran KK, Mittal BR, Bhattacharya A


Department of Nuclear Medicine, PGIMER, Chandigarh, India

The aim of the study was to determine the incremental role of 131 I SPECT-CT in deciding the dose for radioablation. We retrospectively analysed data of 53 patients (40F; 13M) Age range 19 to 65 yrs) of differentiated thyroid cancer (DTC). These included 46 with papillary thyroid cancer (PTC), 6 with follicular thyroid cancer (FTC) and 1 with hurthle cell cancer (HTC). At 6 weeks after total thyroidectomy all patients underwent planar WBS 48 hours after oral administration of 2mCi of 131 I. SPECT-CT of the abnormal foci of 131 I uptake was performed after planar imaging. WBS showed foci of tracer uptake in the anterior neck in 51 patients (average uptake 2.1%, range 0.5 to 10.4%). 18 patients of PTC showed additional foci of tracer uptake in anterior neck. 3 patients (2 PTC,1FTC) showed abnormal tracer uptake (1 patient with diffuse and two with distinct foci) in the chest. 5 patients showed foci of tracer uptake in suspicious for skeletal metastases. SPECT-CT images showed tracer uptake only in thyroid bed in 27 patients, thyroid bed plus lymph nodes in 19 patients (level VI in 16, level I in one patient) one patient in superior mediastinal lymph nodes and one patient in left supraclavicular lymph node. In 5 patients who showed uptake in thyroid bed and suspicious foci for bone uptake-SPECT/CT localised the abnormal foci in 3 patients to bones confirming bony metastases (1 in skull,1 in sternum, 1 in acetabulum) and excluded bony metastases in 2 patients by accurately localising abnormal uptake to caecum.2 patients with focal uptake in chest were confirmed to have lung metastases as SPECT/CT localised tracer uptake to lung metastases. It is concluded that on planar WBS, it is difficult to differentiate tracer uptake in thyroid bed from level VI lymph nodes and the exact anatomical sites of distant foci cannot be known. SPECT-CT had incremental diagnostic value in 48% (24/51) of patients by providing anatomical co- relates to the sites of abnormal 131 I uptake. Clinical relevance statement: As per ATA guidelines empirical dose for ablation is 30 to 100mCi of 131 I for remnant, 100 to 150mCi for cervical lymph nodes and 150 to 300mCi for distant bone metastasis. Addition of SPECT-CT to planar WBS guides in deciding the appropriate dose for 131 I ablation following total thyroidectomy.

Keywords: Radioiodine, SPECT-CT, Ca thyroid

THY 04 (POSTER)

Owl's eye appearance A case report

Mathur Mukul, Asha P


Jawaharlal Nehru Cancer Hospital and Research Centre, Idgah Hills, Bhopal

Hyper-functioning thyroid nodule may present various scintigraphic appearances on thyroid scans. Autonomously hyper functioning thyroid nodules often show degenerative changes. These changes may give rise to peripheral photopenic areas on a thyroid scan. In this report we present a case of hyper functioning nodule showing appearance of an owl's eye. Although rare, such pattern can be seen in a variety of benign and malignant thyroid conditions. A 42-year-old man presented with a solitary thyroid nodule in the right lobe and weight loss for four months. The thyroid hormone profile confirmed hyperthyroidism. Thyroid function testing revealed T4=136.8 nmol/l (Normal = 66.0-181.0nmol/L) and Thyroid Stimulating Harmone (TSH) = 0.283 (Normal =0.27- 4.2 μIU /ml). Antithyrglobulin antibodies and antimicrosmal antibodies were negative. The patient was referred for thyroid scan and uptake. A Thyroid scan was obtained after the intravenous injection of 5 mCi (185MBq) of Tc-99m pertechnetate. Anterior view obtained using a parallel hole collimator. The scan showed peripheral photopenic area with a central focal area of increased uptake giving the appearance of " Owl's eye". 99mTc-pertechnetate uptake was increased. A scintigraphic "Owl's eye" sign has been described in thyroid cyst, benign autonomous nodule and papillary carcinoma of the thyroid gland. This Owl's eye pattern appears to be caused by a focus of functioning tissue overlapping a large cold area in a nodule that has cystic,degenerative and necrotic changes in the middle of a benign and malignant pathology. Hyper functioning nodules may scintigraphically show Owl's eye pattern due to intra nodular degeneration, with residual hyper functioning tissue within or overlapping the degenerative area.

Keywords: Owl 'seye sign, hyperthyroidism, thyroid scan

THY 05 (POSTER)

Prevalence of measurable levels of thyroglobulin antibody among patients suffering from differentiated thyroid carcinoma in the west coast of the Indian subcontinent

Pandit N, Alby T, Kumar R, Bhushan S, Upadhaya I, Bhat V, Oommen S, Shetty D


Department of Nuclear Medicine, Kasturba Medical College and Kasturba Hospital, Manipal, Karnataka

A retrospective analysis of the case sheets of patients who had undergone high dose 131 I ablation for differentiated thyroid carcinoma during the time period 2005 - 2007 were taken up for the analysis. 47.2% of the total patients were found to have measurable levels of thyroglobulin antibody which is much higher compared to the world literature. Presence of thyroglobulin antibody in the serum give rise to falsely low (high in IRMA) levels of thyroglobulin. Thyroglobulin antibody levels are being used as surrogate marker in such cases but the problem is it takes nearly 3 - 4 years for the antibody levels to come down though the patient may be disease free. Certain other methods of measurement of thyroglobulin and thyroglobulin antibody need to be developed which can separately measure thyroglobulin and thyroglobulin antibody levels.

Keywords: Thyroglobulin, thyroglobulin antibody, differentiated thyroid carcinoma

THY 06 (ORAL)

Detection and treatment of hyperthyroidism in sea costal areas and chemically polluted areas in Gujarat, (western part) India

Om Prakash, Mayank M, Rachh S, Patel N, Patel KM, Soni MK, Bhatt V


Gujrat Cancer and Research Institute, Ahmedabad, India

Introduction: Thyrotoxicosis results from a high level of thyroid hormone in blood. I-131 therapy for this is very safe treatment. Surgery is not acceptable in youngers because of cosmetic point of view. Objective: In India most of thyrotoxicosis occurs in sea costal region and hypothyroidism in himalyan region. The main objective of this study to evaluate, the effect of geographical distribution and chemical pollution on thyroid. To calculate exact dose based on gland size. Materials and Methods: 160 patients of primary hyperthyroidism were selected. Age group range between 15-65 yrs. All patients from Gujarat (India) it is located in western part of India. It's sea cost is approx. 1600 km long. here asia's largest chemical zone is situated. Method: 5ml of blood collected from each patient. T3,T4 and TSH test done by RIA and IRMA techniques. after that 99mTco4- Scintigraphy done by gamma camera(GE infinia) 15 days before administration of I-131 all iodine containing food and drugs had been stopped, even iodized salts also. 20 patients got fixed dose of I-131 10 mci per patient.140 patients got 120 micro curie per gram of thyroid tissues weight. follow up study done after 6 months of I-131 administration. Thyroid function test and scintigraphy done to evaluate pre and post therapy changes. Result: 60% of treated patients from sea costal area,25% from chemical and 15% from planes. the patients who got fixed dose 10 mci I-131, of them 35% became hypothyroid and 3% got 2 nd dose (13-15 mci) other group who got 120 micro curie I-131 per gram of thyroid tissue of them only 10% became hypothyroid but 5.4% had been treated with 20% more I-131 than primary dose. in the age group of 50-65 yrs on ECG cardiac arrhythmia detected. Conclusion: In treatment of thyrotoxic patients 120 micro curie /gram group shows better result than fixed dose 10 mCi. 60% of treated patients were from sea costal range, but 25% patients were from chemically polluted zone is guiding us to do mass survey.but in this procedure we need man power, more instruments and financial help.

Keywords: Scintigraphy, thyrotoxicosis, 99mTco4-, chemical pollution

THY 07 (ORAL)

Comparison of fixed low dose versus high dose radioactive iodine for the treatment of hyperthyroidism: Retrospective multifactorial analysis impacting the outcome of therapy

Suresh Kumar AC, Malhotra G, Basu S, Asopa RV


Radiation Medicine Centre, BARC, Tata Memorial Centre Annexe, Jerbaiwadia Road, Parel, Mumbai - 400 012, India

Background: Radioactive iodine (1-131) as a fixed dose protocol is widely used for treatment of hyperthyroidism. However, there is no consensus on the best optimum dose for an individual patient. The objectives of this study were to observe the outcome of I-131 therapy in patients of primary hyperthyroidism in relation to fixed low dose versus high dose regimen, impact of antithyroid drugs and influence of thyroid gland size on therapy outcome. Materials and Methods: Study design: Retrospective analysis. Study group included 287 diagnosed patients of primary hyperthyroidism who had undergone I-131 therapy for the first time (68 M, 219 F; Mean age ± S.D: 43.84 ± 12.53). All patients with low RAIU, thyrocardiac disease were excluded. Details of antithyroid (ATD) drug treatment were recorded. Analysis was done from 2002 till patients became euthyroid/hypothyroid or until January 2010. Each patient's response was evaluated initially at 6 weeks and thereafter every three months. Appropriate statistical tests were applied to compare treatment response between the groups. A P value<0.05 was considered significant. Results: Of 287 patients, 209 patients had been administered low dose [Mean ± S.D: 4.68 ± 0.62 mCi] while 78 patients had received high dose [Mean ± S.D: 9.15 ± 1.05 mCi] of radioiodine. 57.9% (121/ 209) patients in the low dose group responded as compared to 75.6% (59/78) in high dose group after a follow up of more than 36 months. Similarly, among patients with and without antithyroid drug treatment, grade II and above goiters the response rates were significantly higher for high dose group as compared to low dose group. Conclusion: We suggest that high dose radioiodine treatment with 8 to 10 mCi is effective in treating hyperthyroidism in patients with a better success rate than the low dose treatment with 3 to 5 mCi. This is also likely to be helpful in patients who have not received antithyroid drugs. It appears that clinically relevant contribution of antithyroid drugs in causing failure of low dose therapy may be overcome by administering larger amounts of radioiodine.

Keywords: Radioiodine therapy, low dose radioiodine, high dose radioiodine, antithyroid drugs, goiter

THY 8 (ORAL)

Long-term outcome of lobar ablation in differentiated thyroid cancer (DTC): A comparative study with patients of completion thyroidectomy

Santra Amburanjan 1 , Maharjan S, Bal C


Department of Nuclear Medicine, Medical College, Kolkata, India, Department of Nuclear Medicine, 1 All India Institute of Medical Sciences, New Delhi, India

Background: Completion thyroidectomy (CT) is usually recommended after partial surgery in patients with differentiated thyroid cancer. Radioiodine lobar ablation (RAILA) is an easy alternative and avoids complications that might be associated with re-surgery. But its effectiveness in terms of long-term outcome and recurrence free survival is yet to be established. This study was aimed to compare long term outcome of RAILA with that of completion thyroidectomy. Materials and Methods: A retrospective analysis was done from the case records of patients treated in our thyroid clinic for last 25 years. Records of all patients of RAILA (364) and CT (372) were analyzed. Complete ablation rate, cumulative dose needed for complete ablation, Recurrence rate and recurrence free survival was estimated in each group. Comparison was made between two groups by statistical method. Results: There was 73% ablation rate at 1 st dose of RAILA itself. Second dose in LA and first dose of remnant ablation after CT is comparable (92% & 93% respectively). Cumulative dose to achieve 100% ablation rate is more for RAILA group. Seven patients developed recurrence in RAILA group, compared to 14 in CT group. No statistically significant difference was noted between recurrence rate and recurrence free survival between two groups. Conclusion: Radioiodine Lobar ablation is a safe, effective and less costly alternative to completion thyroidectomy in patients with differentiated thyroid cancer with comparable long term outcome like recurrence rate and recurrence free survival.

Keywords: Differentiated thyroid cancer, hemithyroidectomy, completion thyroidectomy, lobar ablation, long-term outcome

THY 9 (ORAL)

Role of post-therapy 131 Iodine SPECT-CT in risk stratification and management of patients with differentiated thyroid cancer

Agrawal K, Bhattacharya A, Harishankar CNB, Manohar K, Mittal BR


Department of Nuclear Medicine, PGIMER, Chandigarh, India

Aim: To determine whether posttherapy 131 I SPECT/CT changed the American Thyroid Association risk of recurrence classification and further management of the patients with differentiated thyroid carcinoma. Materials and Methods: In this prospective study, 33 consecutive patients with thyroid carcinoma (28 papillary, 4 follicular, 1 Hurthle cell) were included. Planar imaging and SPECT/CT were performed 4-7 days after the therapeutic administration of 1,221-5180 MBq (33-140 mCi) of 131 I. SPECT/CT of the neck and upper chest were obtained for all subjects. Additional SPECT/CT scans of the abdomen or pelvis were acquired if planar imaging showed any abnormal focus of uptake. Planar and SPECT/CT images were interpreted independently, and sites of uptake were categorized as residual thyroid uptake, level VI cervical lymph node uptake, level II-V cervical lymph nodal uptake or distant metastasis. An experienced nuclear medicine physician determined if the imaging findings changed the patient's risk category and further management. Results: In 4 of 33 postsurgical patients, SPECT/CT findings changed the initial ATA risk of recurrence classification. In 3 of these 4 patients, WB planar imaging showed distant metastases (1 in lung, 1 in spleen, 1 in left humerus), SPECT/CT confirming these to physiological uptake in breast and intestine and skin contamination respectively. This altered the risk of recurrence from high to intermediate category. In 1 of these 4 patients, WB planar imaging was suggestive of cervical lymph nodal metastasis, but SPECT/CT localized the abnormal focus of uptake to residual thyroid tissue, altering the risk of recurrence from intermediate to low. SPECT/CT changed the further postablation management in 13 out of 33 patients. In 4/13 patients SPECT/CT detected cervical lymph nodes metastases, in 1/13 patient supraclavicular lymph node metastasis was detected, in 7/13 patients distant metastases was confirmed as physiological uptake or contamination of skin and in 1/13 intermediate risk patient was changed to low risk category (thus changing the postablation TSH suppression criteria). Conclusion: SPECT/CT data significantly altered the initial risk of recurrence estimates in 4 of 33 patients (12.12%) and changed subsequent patient management in 13 out of 33 patients (39.39%). This study suggests that 131 Iodine SPECT/CT has a significant role in the management strategy of differentiated thyroid cancer.

Keywords: Post radioiodine therapy, SPECT-CT, Risk stratification

THY 10 (POSTER)

Significance of liver to thigh (L/T) ratio in well differentiated thyroid cancer

Jain S, Pradhan PK, Arya A, Madhusudan P, Ora M, Shukla AK


Department of Nuclear Medicine, SGPGIMS, Lucknow, India

Introduction: Visualisation of liver on I-131 scan has been correlated to functioning thyroid cancer tissue. But this has been disputed by some authors. In this study, we have semi-quantitatively analysed liver uptake of I-131 in diagnostic and post-therapy scans by calculating liver to thigh ratios (LTR). Materials and Methods : 247 diagnostic scans and 104 post-therapy scans were analysed. Liver to thigh ratio (LTR) of counts were calculated for diagnostic and post-therapy scans in anterior and posterior images separately. Patients were divided into six study groups based on their disease status (1-Tg negative (S.Tg≤4) and scan negative; 2-Remnant only; 3-Remnant and lymph node metastasis; 4- Tg positive (S.Tg>4) and Scan negative; 5-bone or lung metastasis, and 6-Only lymph node metastasis. Results: There was no significant difference in LTR in anterior (P=0.246) or posterior images (P=0.281) but good correlation between low dose and high dose scans in both anterior(r=0.797) and posterior images (r=0.855). Comparison of LTR between different study groups (1 to 6) with one way ANOVA test showed significant difference in LTR (P=.000). On applying post-Hoc Test (SNK Test) [95% confidence limits], study group 5 (bone or lung metastasis) showed significantly higher mean LTR (4.6) compared to other groups. Overall, there was only a weak correlation between S. Thyroglobulin and LTR (r=0.395). Conclusion: Visualisation of liver in I-131 scans is not dependent on S Thyroglobulin alone. Presence of functioning metastatic tissue (like bone or lung metastasis which release thyroid hormones and thereby lower serum TSH) is also an important factor.

Keywords: Radioiodine scan, thyroid cancer, liver to thigh ratio

THY 11 (ORAL)

Tfficacy to Efficacy of thyroid/parotid ratio in the diagnosis of hyperthyroidism in different environmental conditions: A multi-centric study

Das BK, Pradhan PK 1 , Senthilnathan, MS 2


Department of Nuclear Medicine, Utkal Institute of medical Sciences, Bhubaneswar, 2 Department of Nuclear Medicine, SG PGIMS, Lucknow, 3 Minakshi Super Specialty Medical and Research Centre, Madurai, India

Aim: Thyroid to parotid ratio (TPR) as a simple and cost effective diagnostic test in the evaluation of thyroid disorders was first reported by the author in 1997. Since then several centers have used this procedure for the diagnosis of high uptake thyroid disorders. The purpose of this multi centric study is to prove the validity of this simple technique in different environmental conditions and ethnic populations. Materials and Method: Prospective study which includes following patients: 578 hyperthyroid patients(212 male and 366 females) from northern part of India (endemic goiter region) between Jan. 1996 and Dec. 2002, 43 consecutive hyperthyroid patients(26 male and 17 female) from eastern Malaysia (high dietary iodine) sent for radio iodine therapy between May 2005 and Dec. 2006, 19 consecutive patients (8 males and 11 females) from south India (non- endemic goiter region) clinically and bio chemically hyperthyroid referred between June 2005 and Dec. 2006 and 56 consecutive hyperthyroid patients (16 males and 40 females) from eastern part of India (non-endemic goiter region) between Nov.2008 and Feb. 2010. All patients were subjected to a standard Tc99m thyroid scan. Thyroid to Parotid Ratio (TPR) was calculated after drawing ROIs over the thyroid and parotid glands in anterior projection. Blood samples were taken on the same day for estimation of T3, T4 and TSH. The TPR values were compared with the biochemical parameters. Results: The individual comparison of clinical and biochemical parameters with TPR in hyperthyroid patients showed concordance in over 90% in all the four centers (Lucknow 93.7%, Kelantan 91%, Madurai 96.5% and Bhubaneswar 93.6%). Conclusions: Calculation of TPR is extremely simple without the requirement of syringe counts or adhering to any specific time period after injection. It is highly sensitive and specific in the diagnosis of hyperthyroidism. TPR appears to hold good irrespective of different environmental conditions and different ethnic populations as has been confirmed in this multi-centric prospective study. The morphological information obtained from the scan and the objective TPR value for functional status is sufficient to start definitive therapy on the same day in most cases without waiting for biochemical test results. This is important for patients coming from far off places and from poor socio-economic conditions. Thyroid Scan of a normal patient showing Thyroid to Parotid Ratio (TPR) of 1.30 which is within normal range (left panel bellow). Thyroid Scan of a hyperthyroid patient showing Thyroid to Parotid Ratio (TPR) of 15.26 which is more than six times of the normal value +-2SD (right panel bellow)

Keywords: Thyroid to parotid ratio, Thyroid Scan, thyroid disorders

THY12 (POSTER)

Role of 68Ga-DOTANOC PET/CT in the dedifferentiated thyroid cancer and comparison with 18 F-FDG PET/CT: Preliminary data

Parveen Kundu, Sneh Lata, sunil Jeph, Singh Harmandeep, Rajender, Agagrwal Krishna Kant, Malhotra Arun, Bal CS


AIIMS, New Delhi, India

Aim: To evaluate the role of 68 Ga-DOTANOC PET/ CT in wholebody radioiodine scan negative recurrent differentiated thyroid cancer and comparison with 18 F-FDG PET/ CT. Materials and Methods: In this prospective study 32 patients of differentiated thyroid cancer presenting with increased Tg value and having no abnormal concentration on whole body radioiodine scan were included. Patients underwent both 68 Ga-DOTANOC PET/ CT and 18 F-FDG PET/CT in random order within 4 weeks time interval. Patient showing lesion(s) on either of scan was considered as recurrent disease positive and substantiated by structural imaging. Tumor lesions were categorised according to four sites -local, nodal, pulmonary and skeletal for comparison of detection rate between two functional modalities. Total number of lesions was defined as sum of number of lesions detected by atleast one of the two scans. The analysis is performed on the basis of patient data, and as well as lesion wise. Results: Positive recurrent disease was observed in 24/32 (75%) on either of the scans. In 13/32 (40%) of these patients both imaging modalities detected metastatic disease. In 8/32 (26%) patients disease was detected only by 18 F-FDG PET/ CT and in 3/32 (9%) patients only 68 Ga-DOTANOC PET /CT diagnosed disease. 18 F-FDG PET/ CT and 68 Ga-DOTANOC PET/CT showed moderate agreement (k=0.313, P-value=0.03) in detecting disease on patient basis which is statistically significant. Total number of positive lesions detected on either of the modality was 73. 18 F-FDG PET/CT showed 64/73 (87%) lesions and 68 Ga-DOTANOC PET /CT detected 31/73 (42%) lesions. 18 F-FDG PET /CT and 68 Ga-DOTANOC PET /CT showed 22/73 (30%) concordant lesions. Lesions detected only by 18 F-FDG PET/ CT were 33/73 (45%) and only by 68 Ga-DOTANOC PET/ CT 9/73 (12%). Location-wise tumor lesion detection showed fair agreement between two modalities for local (k=0.720) and skeletal (k=0.6) disease. However, detection for nodal (k=0.32) and pulmonary (k=0.24) sites showed moderate agreement only. Conclusion: Disease detection rate is comparable by 18 F-FDG PET/ CT and 68 Ga-DOTANOC PET/ CT. Though number of lesions detected by 18 F-FDG PET /CT exceeds far more than 68 Ga-DOTANOC PET /CT yet somatostatin receptor based scintigraphy provides one additional tool for diagnosing recurrent disease and provides an option for evaluation of patient for peptide receptor radionuclide therapy. Infact, we have already treated few patients with PRRT.

Keywords: Ga DOTANOC PET-CT, De-differentiated thyroid cancer, FDG PET-CT




 

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