Low-dose fractionated radiation and chemotherapy prior to definitive chemoradiation in locally advanced carcinoma of the uterine cervix: Results of a prospective phase II clinical trial.

BACKGROUND: We investigated the feasibility of neoadjuvant low-dose radiation and chemotherapy with paclitaxel and carboplatin (LDCRT) before radical chemoradiation (CRT) and assessed the feasibility, efficacy, and response rate to such a regimen. METHODS: This is a single-arm phase II trial of 24 patients, with locally advanced squamous cell carcinoma of the cervix (stage IIB-IIIB). Patients received low-dose fractionated radiotherapy, carboplatin (AUC×5) and paclitaxel (175 mg/m(2)), three weekly for two cycles followed by CRT. The primary end point was overall and disease-free survival. RESULTS: Mean age of the patients at diagnosis was 50 years; Radiological complete or partial response rate was 40% and 60%, respectively, post-LDCRT. The median follow-up was 30 months (24-36 months). Both overall and progression-free survivals at 2.5 years were 84%. Grade 3/4 toxicities were 24% hematological toxicity during LDCRT and 46% during CRT (hematological: 42%, non-hematological: 4%). CONCLUSION: A good response rate is achieved by low-dose radiation and chemotherapy with carboplatin and paclitaxel followed by radical CRT. This treatment regimen is feasible and effective as evidenced by the acceptable toxicity and 84% local control at 2.5 years.

Adaptive threshold segmentation of pituitary adenomas from FDG PET images for radiosurgery.

In this study we have attempted to optimize a PET based adaptive threshold seg- mentation method for delineating small tumors, particularly in a background of high tracer activity. The metabolic nature of pituitary adenomas and the constraints of MRI imaging in the postoperative setting to delineate these tumors during radio- surgical procedures motivated us to develop this method. Phantom experiments were done to establish a relationship between the threshold required for segmenting the PET images and the target size and the activity concentration within the target in relation to its background. The threshold was developed from multiple linear regression of the experimental data optimized for tumor sizes less than 4 cm3. We validated our method against the phantom target volumes with measured target to background ratios ranging from 1.6 to 14.58. The method was tested on ten retro- spective patients with residual growth hormone-secreting pituitary adenomas that underwent radiosurgery and compared against the volumes delineated by manual method. The predicted volumes against the true volume of the phantom inserts gave a correlation coefficient of 99% (p < 0.01). In the ten retrospective patients, the automatically segmented tumor volumes against volumes manually delineated by the clinicians had a correlation of 94% (p < 0.01). This adaptive threshold segmentation showed promising results in delineating tumor volumes in pituitary adenomas planned for stereotactic radiosurgery, particularly in the postoperative setting where MR and CT images may be associated with artifacts, provided opti- mization experiment is carried out. 

Long-term disease-free survival after MIBG therapy for metastatic pheochromocytoma.

Pheochromocytomas are rare tumours originating in chromaffin cells, representing 0.1%-1% of all secondary hypertension cases. The majority are benign and unilateral, characterised by the production of catecholamines and other neuropeptides. Mainly located in the adrenal gland, they are more frequent between the third and fifth decades of life. Iodine-131 metaiodobenzylguanidine (131I-MIBG), a radiopharmaceutical agent used for scintigraphic localisation of pheochromocytomas, has been employed to treat malignant pheochromocytomas since 1983 in a few specialised centres around the world. We reviewed our clinical experience in one such case of a young lady who presented with history of abdominal pain, headache and lower back pain. On evaluation, ultrasonography revealed a right adrenal mass and elevated urine vanillylmandelic acid levels. Following surgical resection and histopathological confirmation of pheochromocytoma, MIBG scintigraphy revealed osseous metastases and hence, she underwent 131I-MIBG therapy.

The role of urinary fractionated metanephrines in the diagnosis of phaeochromocytoma.

BACKGROUND & OBJECTIVES: Plasma and urinary metanephrines are used as screening tests for the diagnosis of phaeochromocytoma. The recommended cut-off levels are not standardized. This study was conducted to identify a cut-off level for 24 h urinary fractionated metanephrines viz. metanephrine (uMN) and normetanephrine (uNMN) using enzyme immunoassay for the diagnosis of phaeochromocytoma. METHODS: Consecutive patients suspected to have phaeochromocytoma were included in the study. uMN and uNMN in 24 h urinary sample were measured using a commercial ELISA kit. RESULTS: Overall, 72 patients were included over a period of 18 months. Twenty patients had histopathologically confirmed phaeochromocytoma and in 52 patients phaeochromocytoma was ruled out. Using the upper limit of normal stated by the assay manufacturer as the cut-off, uMN >350 µg/day had a low sensitivity and uNMN >600 µg/day had a poor specificity. By increasing the cut-off value of uNMN to twice the upper limit, specificity increased significantly without much loss in sensitivity. Combining uMN and uNMN using a cut-off twice the upper limit improved the diagnostic performance - sensitivity (95%); specificity (92.3%); positive predictive value (PPV - 82.6%); negative predictive value (NPV - 98%). In subsets of patients with a variable pretest probability for phaeochromocytoma, the PPV correlates well with the occurred of these tumors decreased, while the NPV remained at 100 per cent. INTERPRETATION & CONCLUSIONS: ELISA is a simple and reliable method for measuring uMN and uNMN. The test has a good NPV and can be used as an initial screening test for ruling out phaeochromocytoma. Each hospital will have to define the cut-off value for the assay being used, choosing a proper control population.

Validation of Deauville Score for Response Evaluation in Hodgkin's Lymphoma.

Context: Positron emission tomography (PET) using F-18 fluorodeoxyglucose (FDG) for treatment monitoring in patients with lymphoma is one of the most well-developed clinical applications. Deauville five-point score (DS) is recommended for response assessment in international guidelines. DS gives the threshold for adequate or inadequate response to be adapted according to the clinical context or research question. Aims: We aimed to validate DS in Hodgkin's lymphoma (HL) by retrospectively assigning this score to F-18 FDG PET-computed tomography (CT) studies done before 2016 and analyzing its concordance with the line of management. The secondary aim was to assess the reproducibility of DS in the interpretation of PET-CT scans. Subjects and Methods: A total of 100 eligible consecutive patients underwent F-18 FDG PET-CT scans between January 2014 and December 2015. Their interim, end of treatment, and follow-up PET scans were retrospectively visually analyzed and assigned DS by three nuclear medicine physicians. Concordance was defined as agreement between the DS assigned and the line of treatment. Interobserver variability was calculated using weighted Kappa and presented with 95% confidence interval. Results: Among 212 scans assigned DS, 165 scans showed agreement between the DS and line of treatment. Of these, 95.2% of scans scored DS 1-3 were kept on following or the same treatment plan was continued and patients did well. Among the scans that showed discordance, 24 scans scored DS 4/5 were continued on the same treatment regimen and the next assessment showed disease progression. Conclusions: Our study confirmed that DS is a useful tool to aid in reporting F-18 FDG PET-CT in the management of HL with good positive and negative predictive values. This study also demonstrated good interobserver agreement.

Analysis of discordant PET and CT findings in 18F-FDG PET-CT scans in the management of oncology patients.

BACKGROUND: Discordant findings are often noted between PET-CT and CT images of 18F-FDG PET-CT scans and cause ambiguity in image interpretation. This study aimed at determining the significance of these findings in the management of oncology patients. CONTEXT: Discordant findings are often noted between PET-CT and CT images of 18F-FDG PET-CT scans and cause ambiguity in image interpretation. AIM: This study aimed at determining the significance of these findings in the management of oncology patients. METHODS: This was an observational, descriptive study. Hence, retrospective analysis of all discordant findings in oncology patients undergoing a PETCT imaging between Jan 2013 and Jan 2016 was done. Those patients who had a follow-up period of minimum 1 year in either of the following forms - repeat PETCT imaging, other radiological imaging, clinical, or histopathological evidence were included. From all the discordant lesions, the sensitivity, specificity, positive predictive, negative predictive value, and accuracy of both PET-CT and CT modalities were determined. RESULTS: Of 348 discordant lesions, 16.7% was noted in soft tissues, 25% in viscera, 28.7% in lungs, 14.1% in lymph nodes, and 15.5% in bones. At the end of follow-up, 15.2% lesions were PET true positive, 57.5% PET true negative, 10.1% CT true positive lesions, 13.8% CT true negative, and 3.4% were inconclusive. CONCLUSION: 18F-FDG PET-CT is superior to CT imaging and should be considered as the first-line imaging modality in oncology patients.

Assessment of left ventricular systolic function by velocity vector imaging.

OBJECTIVES: To study the usefulness of a novel echocardiographic technique, velocity vector imaging (VVI) in the measurement of left ventricular ejection fraction (LVEF). BACKGROUND: Ejection fraction measured by echocardiography forms the cornerstone in the assessment of LV systolic function. Errors in measurement of EF by routine two-dimensional echocardiography (2D ECHO) limit its utility. The VVI is a new technology which uses speckle tracking and other algorithms to track the endocardial border. This may help in more accurate assessment of EF. METHODS: Global and regional LVEF was measured in 49 patients using VVI, 2D ECHO and radionuclide-gated single photon emission computed tomography (SPECT). Results were categorised as normal, mild, moderate, or severe LV systolic dysfunction based on American Society of ECHO classification. The results were analysed by appropriate statistical tests for correlations. RESULTS: The mean EF was 35 ± 12.08% by VVI, 54.2 ± 19.51% by SPECT (P< 0.001 vs VVI) and 50.3 ± 8.92% by 2D ECHO (P < 0.001 vs VVI). There was weak linear positive correlation between EF measured by VVI and the other modalities (Pearson's correlation coefficient 0.577 for SPECT and 0.573 for 2D; P=0.01). The VVI systematically underestimated the EF compared to SPECT. Greater number of patients had moderate or severe LV systolic dysfunction by VVI (37; 74.5%) than by SPECT (17; 34.7%; P=0.037). We derived a correction factor to calculate SPECT EF from VVI EF as follows: EF (SPECT) = EF (VVI) × 0.9 + 21 or approximately VVI (EF) + 20. CONCLUSION: Measurement of EF by VVI is feasible. The VVI underestimated the EF when compared to nuclear-gated SPECT in this study. The accuracy of this technology and the need for a correction factor needs to be assessed in future studies.

F-18 FDG PET-CT for response evaluation in head and neck malignancy: Experience from a tertiary level hospital in south India.

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) accounts for 90% of head and neck cancers. There has been no established qualitative system of interpretation for therapy response assessment using PET-CT for HNSCC. AIM: To assess response evaluation of nodal status in post-treatment PET-CT scans in HNSCC using a 5-point Likert scale (Deauville score [DS]). METHODS AND RESULTS: Retro-prospective analysis was performed of the nodal status of pre and post-RT PET-CT in patients diagnosed with HNSCC (n = 43) from May 2013 to March 2018. All eligible patients underwent a pre-RT PET-CT scan before the start of RT. Another post-RT PET-CT scan was performed 12 weeks after the completion of RT. The median time from completion of radiotherapy (RT) to post-RT PET-CT was 92 days; 80% of the patients had their post-RT PET-CT scan between 77 and 147 days after therapy. Of 43 patients (M/33, F/10, age range 18 to 80 years (median 54 years) selected for the study, good concordance was noted between DS and clinical response in these patients. The change in SUV from pre-RT PET to post-RT PET was analyzed using a paired t-test. The P-value was found to be statistically significant while comparing pre and post-RT SUVmax levels showing that RT had significantly reduced the SUVmax levels of the nodes in DS 2-3 groups whereas the number of patients was too small to allow a reliable calculation in DS 4-5 groups. It was found that 36/39 patients with DS 1-3 had no nodal recurrence showing a high NPV of 92.3%. Of the four patients with DS 4-5, all had active disease showing PPV of 100%. Applying Fisher's exact test, the P-value was found to be .004. CONCLUSION: DS seems to satisfy the requirements for a simple qualitative method of interpreting PET scans and for identifying patients requiring neck dissection. Consensus regarding qualitative assessment would facilitate standardization of PET reporting in clinical practice and enable comparative multicentric studies.

Yttrium-90 Synovectomy in Hemophilic Arthropathy: An Institutional Experience for 15 Years.

OBJECTIVE: The objective of this study is to assess the efficacy of Yttrium-90 (Y-90) radiation synovectomy in decreasing the recurrent bleeding episodes in hemophilic joints. SUBJECTS AND METHODS: A retrospective analysis of patients who had Y-90 synovectomy from January 2001 to January 2016 was done. Among them, patients with minimum follow-up of 6 months were selected. The response in terms of decrease in the number of bleeding episodes was evaluated. RESULTS: A total of 167 patients (243 joints) with hemophilia had radiation synovectomy over 15 years. Those with a minimum follow-up of 6 months were 155 joints (115 patients). The age ranged from 5 to 43 years and included 113 male and two female patients. Data for 11 joints were unavailable as these patients were lost to follow-up. The assessment of response for the remaining 144 joints was done based on the data available for different follow-up periods. They were divided into the following - 7 months to 2 years (89 joints), 3-5 years (6 joints), 6-10 years (39 joints), and above 11 years (10 joints). Overall, 37.4% of the joints had complete response, 56% had partial response, and 6% of the joints had no response. CONCLUSION: Radiation synovectomy is a noninvasive and effective modality which decreases the bleeding episodes in hemophiliac joints and improves the quality of life remarkably.

Ga-68 DOTATATE Positron Emission Tomography-Computed Tomography Imaging in Oncogenic Osteomalacia: Experience from a Tertiary Level Hospital in South India.

AIM: Utility of Ga68 DOTATATE PETCT imaging to localise cause for oncogenic osteomalacia (OOM). MATERIALS AND METHODS: Retrospective analysis between March 2015 to March 2018 of all patients with a clinical diagnosis (based on a combination of clinical history, hypophosphatemia and elevated FGF-23 values) of OOM who underwent Ga-68 DOTATATE PET/CT. RESULTS: Total of 27 patients had undergone Ga-68 DOTATATE PET/CT imaging in our centre from March 2015 to March 2018. Of these 16 patients with clinically suspected oncogenic osteomalacia were included in our study. Age range 18-61 years of which 12 were males. Total of 13 (81.25%) patients were found to be positive on imaging for a possible mesenchymal tumour. Most common site of tumour was the lower limb (76%). Most common presenting symptom was bone pain (81%) followed by muscle weakness (19%). Overall, 10 patients underwent surgery, all of whose biopsy was reported as phosphaturic mesenchymal tumour. During the three month follow up, serum phosphorous measured in 15/16, post-surgical/ medical treatment had normalised in all except two patients who had undergone only medical therapy with neutral phosphate. Fall in FGF-23 was more pronounced in surgically treated patients as compared to those who received medical treatment. CONCLUSION: Ga68-DOTATE PET/CT is a useful investigatory modality for localizing cause for oncogenic osteomalacia.

Is hemi-thyroidectomy adequate in low risk differentiated thyroid cancer?

In low-risk differentiated thyroid carcinoma (LRDTC), appropriate surgical procedure in terms of hemi/total thyroidectomy (TT) has been an area of debate. The aim was to determine whether in LRDTC patients, hemithyroidectomy would be an adequate treatment, determine incidence of disease in contralateral lobe and evaluate the effect of radioactive iodine ablation (RAIA). Retrospective study was done from 2008 to 2014 at a single institution. Preoperative ultrasound (USG) and histopathology reports of all LRDTC patients following total/completion thyroidectomy were recorded. Details of postthyroidectomy, thyroid whole body scan, and stimulated serum thyroglobulin (sTg) levels were also documented and results analyzed. A total of 114/562 patients met inclusion criteria. Of these, 25/114 (22%) underwent hemithyroidectomy followed by a completion thyroidectomy while remaining 89/114 (78%) underwent TT initially. Preoperative USG detected single-lobe involvement in 44 patients; however, among them, histopathology revealed bilateral lobe disease in 17 (38.6%). There was a significant fall of sTg level following RAIA as compared to that before RAIA in T1b-T2 (P = 0.009 and 0.012, respectively). Median follow-up was 2 years (range: 1-7 years) with no distant metastasis or deaths recorded till 2017, except for one local recurrence 4 years after RAIA. In conclusion, the role of TT in LRDTC patients is important as 46% of patients were found to have tumor in contralateral lobe as well. Significant fall in sTg levels following RAIA justifies RAIA of remnant lobe even in LRDTC (T > 1a). It facilitates early detection of recurrence when sTg alone is used for follow-up.

Stimulated Serum Thyroglobulin Levels versus Unstimulated Serum Thyroglobulin in the Follow-up of Patients with Papillary Thyroid Carcinoma.

Serum thyroglobulin (Tg) and thyroid whole-body radioiodine scintigraphy (TWBS) are used in the follow-up of patients with papillary thyroid carcinoma (PTC) after total thyroidectomy. Symptoms of hypothyroidism are frequent as patients discontinue levothyroxine 1 month before visit, favoring the use of unstimulated serum Tg (uSTg) only. This study was done to determine the reliability of stimulated serum Tg levels (sSTg) over uSTg. A total of 650 patients with PTC came for follow-up between June 2011 and 2016. In those who had levels of uSTg and sSTg months measured within an interval of median of 3 months (range from 1 to 8 months), risk stratification was done as per the American Thyroid Association guidelines 2015. Intervention was based on a cutoff value of sSTg >10 ng/ml in our institution and the same was used for data analysis. Out of 650 patients, 106 had paired Tg values. Low-, intermediate-, and high-risk groups comprised 40, 31, and 35 patients, respectively. The sSTg >10 ng/ml with uSTg <10 ng/ml in the same patient was noted in 22.5% (9/40) of the low-risk, 41.9% (13/31) of the intermediate-risk, and 14.2% (5/35) of the high-risk groups. The levels were corroborated with tumor burden as determined by additional clinical, ultrasonography neck, and TWBS findings. Our study highlights the superiority of sSTg over uSTg in the follow-up of PTC patients. Follow-up with uSTg alone may result in underestimating the tumor burden.

Medullary thyroid carcinoma: a 20-year experience from a centre in South India.

BACKGROUND: Management of medullary thyroid carcinoma (MTC) remains controversial despite many advances over the past five decades. We attempt to review the presentation, management and prognosis of MTC at our institution over the last two decades. METHODS: We conducted a retrospective review of the records of 40 patients with MTC over a period of 20 years. RESULTS: Ten patients had hereditary MTC and 30 had sporadic MTC. The mean age of presentation was 41 years. Sixty-five per cent of the patients had a definite thyroid swelling and 43% had lymphadenopathy at the time of presentation. Total thyroidectomy with a central neck dissection was carried out in 82.5% of patients. Adjuvant therapy was given in 75% of patients because of extensive/residual disease. Postoperative hypercalcitoninaemia was seen 73% of patients. (131)I metaiodobenzylguanidine scanning was carried out in 16 patients with persistent hypercalcitoninaemia; the uptake was positive in 10 and negative in 6, indicating a positivity of 62%. CONCLUSION: Medullary thyroid carcinoma accounts for 2.5% of thyroid carcinomas. There is a small male preponderance. In our series (131)I metaiodobenzylguanidine scan had a better positivity than what has been reported in the published work. Persistent postoperative hypercalcitoninaemia was associated with a poorer prognosis that did not reach statistical significant.

In-house preparation of iodine -131 metaiodo benzyl guanidine for scintigraphy of neuroendocrine tumors. Fourteen years experience in South India.

Iodine-131 metaiodobenzyl guanidine ((131)I-MIBG) is routinely used for imaging and treatment of neuroendocrine tumors (NET). As the commercially available radiopharmaceutical was very expensive, we developed an in-house method of labeling MIBG with (131)I in 1993. A total of 247 batches of (131)I-MIBG were prepared and used in our hospital between April 1993 and September 2006. We report our experience over these 14 years of preparation of this tracer in our hospital radiopharmacy, for the scintigraphy of NET. The technique of preparation is simple and the labeled product was found to be of acceptable quality. With the routine availability and cost effectiveness, the utilization of this radiopharmaceutical for scintigraphy increased remarkably in our institution.

Paget's disease of bone: experience from a centre in southern India.

BACKGROUND: Paget's disease is a localized disorder of the skeleton characterized by increased osteoclastic activity. While the prevalence in the Western Population is 1-2%, the prevalence in India is not known. We studied the clinical profile, biochemical parameters, bone scans, therapeutic details and follow up data of patients with Paget's disease, attending the Endocrinology outpatient clinic in our institution. METHODS: A retrospective review was done of the medical records of 51 patients seen in a tertiary referral centre in Southern India from 1995 to 2003. The data was analyzed using SPSS 9.0 software package. RESULTS: There were a total of 51 patients (41 male and 10 female). The mean age at presentation was 56 years and the mean duration of symptoms was 43 months. At least 6 months of follow-up was available in 31 patients and longer term (>2 years) follow-up in 22 patients. The symptoms at presentation were bone pain in 65%, low backache in 37%, skeletal deformities in 33%, pathological fractures in 20%, neurogenic claudication in 4%, deafness and head enlargement in 7% and renal stones in 4% of subjects. Five patients (9.8%) were asymptomatic and were incidentally diagnosed during evaluation of an elevated alkaline phosphatase. The mean serum alkaline phosphatase (range and SD) at the time of presentation was 690 IU/L (91-3873 U/L, 698 U/L). There was no statistically significant difference in the serum alkaline phosphatase values between female and male patients (576 U/L versus 718 U/L). Polyostotic involvement was seen in 90.2% of the patients. The pattern of skeletal involvement was very similar to that described in the Western literature. Twenty patients were started on Calcitonin and of these, 13 patients were later changed over to bisphosphonates to induce remission. In all, thirty six subjects received Alendronate and of them, 31 received lower doses (10-20mg/day). All the treated patients showed a good clinical and biochemical improvement. Two patients with severe Pagetic involvement of the bone who also had neurologic symptoms (root pains in one and cauda equina lesion in the other) needed intravenous Pamidronate to obtain a rapid response in the initial phase of treatment. CONCLUSIONS: In our series, Paget's disease had a male predominance. The clinical presentation and the pattern of skeletal involvement was similar to the Western series. Serum alkaline phosphatase declined by 40% at 6 months of therapy and by 64% by one year of treatment in patients who were on lower doses of Alendronate (10-20 mg/day) in our series, which is similar to what has been described with conventional doses (40 mg per day) in the Western series.

No impact of dietary iodine restriction in short term development of hypothyroidism following fixed dose radioactive iodine therapy for Graves' disease.

BACKGROUND: The increased incidence of autoimmune thyroid disease with increasing dietary iodine intake has been demonstrated both epidemiologically and experimentally. The hypothyroidism that occurs in the first year following radioactive iodine therapy is probably related to the destructive effects of the radiation and underlying ongoing autoimmunity. OBJECTIVE: To study the outcomes at the end of six months after fixed dose I, (131)therapy for Graves' disease followed by an iodine restricted diet for a period of six months. MATERIALS AND METHODS: Consecutive adult patients with Graves' disease planned for I(131) therapy were randomized either to receive instructions regarding dietary iodine restriction or no advice prior to fixed dose (5mCi) I(131) administration. Thyroid functions and urinary iodine indices were evaluated at 3(rd) and 6(th) month subsequently. RESULTS: Forty seven patients (13M and 34F) were assessed, 2 were excluded, 45 were randomized (Cases 24 and Controls 21) and 39 patients completed the study. Baseline data was comparable. Median urinary iodine concentration was 115 and 273 µg/gm creat (p = 0.00) among cases and controls respectively. Outcomes at the 3(rd) month were as follows (cases and controls); Euthyroid (10 and 6: P = 0.24), Hypothyroid (3 and 5: P = 0.38) and Hyperthyroid (7 and 8: P = 0.64). Outcomes at the end of six months were as follows (cases and controls); Euthyroid (10 and 5: P = 0.12), Hypothyroid (3 and 5: P = 0.38) and Hyperthyroid (7 and 9: P = 0.43). Of the hypothyroid patients 5 (cases 1 and controls 4: P = 0.13) required thyroxine replacement. CONCLUSIONS: There was no statistical significant difference in the outcome of patients with dietary iodine restriction following I(131) therapy for Graves' disease.

Role of conventional and diffusion weighted MRI in predicting treatment response after low dose radiation and chemotherapy in locally advanced carcinoma cervix.

BACKGROUND AND PURPOSE: To assess the diagnostic performance of conventional and diffusion weighted (DWI) magnetic resonance imaging (MRI) in predicting response in locally advanced cervical cancer. MATERIALS AND METHODS: Total 24 patients with stage IIB-IIIB squamous cell carcinoma cervix were treated with initial two cycles of paclitaxel and carboplatin and concurrent low dose radiotherapy prior to standard chemoradiation. Response was assessed clinically and radiologically after 3 weeks of initial treatment. Volumetric and functional parameters derived from conventional and diffusion weighted MRI, due to treatment were measured. RESULTS: Significant reduction of GTV was noted in MRI (54 cm(3) vs. 11 cm(3), p < 0.01) and DWI (44 cm(3) vs. 6 cm(3), p < 0.01, ΔADC = 0.49 × 10(-3)mm(2)/sec, p < 0.01) after treatment. Tumor volume reduction rate (TVRR) in DWI was significantly higher in pathological good responders (p = 0.03). In this group both mean post treatment apparent diffusion coefficient (ADC) value and ΔADC were significantly higher (p = 0.01 and p = 0.03). ADC was a good predictor for pathological response (area under receiver operating characteristic curve (ROC) 0.814). CONCLUSION: TVRR (DWI) and ΔADC can be used as a predictor of early pathological response. Complete response based on DWI, could be a useful predictor of long term disease control.

Diagnostic Utility of PET CT in Thymic Tumours with Emphasis on 68Ga-DOTATATE PET CT in Thymic Neuroendocrine Tumour - Experience at a Tertiary Level Hospital in India.

INTRODUCTION: 18 Fluorine-fluoro-2-deoxyglucose positron emis-sion tomography/computed tomography (18F- FDG-PET/CT) is of importance in assessing high-risk thymoma and thymic carcinomas. Detection of advanced thymoma versus thymic carcinoma by routine cross sectional anatomical imaging such as computed tomography (CT), magnetic resonance imaging (MRI) often poses a diagnostic dilemma. In this case series we observed the utility of FDG uptake to predict advanced thymoma and distinguish thymoma from thymic cancer. MATERIALS AND METHODS: We reviewed 18F- FDG-PET/CT scans of 12 patients (8 males, 4 females); age 24-60yrs with thymic epithelial malignancy from January 2011 to May 2013. FDG activity in lesions was quantified using maximum standardised uptake value (SUVmax) and correlated with Masaoka staging and WHO classification. All patients fasted 4 hr prior to 18F-FDG PET/CT. Images from vertex to mid-thigh were acquired 60min post injection of 3.7 -4.7 MBq/kg (Mega Becquerel)/kilogram of18F-FDG and SUV max of each tumour was measured. One patient underwent DOTATATE scan, received 138MBq of 68Gallium (68Ga)-DOTATATE injection IV and imaging was done after 60 min. RESULTS: Higher FDG uptake of SUVmax 7.35 was seen in type B3 thymoma. FDG uptake was higher in thymic carcinoma (20.45 in primary and 17.46 in the node) or neuroendocrine differentiation (NED) than in patients with thymomas (ranged 7.35 - 3.02). No significant association was observed between higher focal FDG uptake and advanced-stage disease in thymoma. In NED 68Ga - DOTATATE imaging identified more lesions than in FDG. CONCLUSION: PET CT is a valuable diagnostic tool in evaluation of thymic tumours, to assess in initial workup, for treatment response and for prognostication. 68Ga-DOTATATE PET/CT is beneficial in assessing neuroendocrine thymic tumours. Focal FDG uptake cannot predict advanced thymoma but is helpful in distinguishing thymoma from thymic carcinoma, or the more aggressive thymoma B3.