Sneh Lata

Role of (68)Ga-DOTATOC PET-CT in the diagnosis and staging of pancreatic neuroendocrine tumours.

ObjectiveThe objective of the present study was to evaluate the role of 68Ga-DOTA(0)-Phe(1)-Tyr(3)-octreotide (68Ga-DOTATOC) positron emission tomography computed tomography (PET-CT) for detection and staging of pancreatic neuroendocrine tumours (NETs).MethodsTwenty patients with clinically suspected and/or histopathologically proven pancreatic NET underwent 68Ga-DOTATOC PET-CT imaging for staging and /or localisation of primary lesion. They also underwent contrast enhanced CT (CECT) and 8 patients underwent 18F-FDG PET-CT. SUVmax of primary and metastatic lesions were measured. Results were verified with histopathology for primary tumour and with clinical follow up/MRI and /or biopsy for metastatic disease. Results of 68Ga-DOTATOC PET-CT were compared to CECT and 18F-FDG PET-CT.Results68Ga-DOTATOC PET-CT correctly localised primary in all 20, CECT in 15 and 18F-FDG PET-CT in 2 patients. 68Ga-DOTATOC PET-CT demonstrated metastases in 13 patients, CECT in 7 and 18F-FDG PET-CT in 2. 68Ga-DOTATOC PET-CT emerged as the best investigation with 100% sensitivity and PPV for detecting primary tumour and metastatic disease. The detection rate of CECT was lower than 68Ga-DOTATOC PET-CT, both for primary tumour (20vs.15) or metastatic disease (13vs.7). 18F-FDG PET-CT performed poorly for primary and metastasis.ConclusionGa-DOTATOC PET-CT is a very useful imaging investigation for diagnosing and staging pancreatic NET.

Dual tracer functional imaging of gastroenteropancreatic neuroendocrine tumors using 68Ga-DOTA-NOC PET-CT and 18F-FDG PET-CT: competitive or complimentary?

Objective This study aimed to compare the diagnostic performance of 68Ga-DOTANOC PET/CT with 18F-FDG PET/CT in the patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Patients and Methods Data of 51 patients with definite histological diagnosis of GEP-NET who underwent both 68Ga-DOTA-NOC PET-CT and 18F-FDG PET-CT within a span of 15 days were selected for this retrospective analysis. Sensitivity, specificity, and predictive values were calculated for 68Ga-DOTA-NOC PET-CT and 18F-FDG PET-CT, and results were compared both on patientwise and regionwise analysis. Results 68Ga-DOTA-NOC PET-CT is superior to 18F-FDG PET-CT on patientwise analysis (P < 0.0001). On regionwise analysis, 68Ga-DOTA-NOC PET-CT is superior to 18F-FDG PET-CT only for lymph node metastases (P < 0.003). Although 68Ga-DOTA-NOC PET-CT detected more liver and skeletal lesions compared with 18F-FDG PET-CT, the difference was not statistically significant. In addition, the results of combined imaging helped in selecting candidates who would undergo the appropriate mode of treatment, whether octreotide therapy or conventional chemotherapy Conclusions 68Ga-DOTA-NOC PET-CT seems to be superior to 18F-FDG PET-CT for imaging GEP-NETs. However, their role seems to be complementary because combination of 68Ga-DOTA-NOC PET-CT and 18F-FDG PET-CT in such patients helps demonstrate the total disease burden and segregate them to proper therapeutic groups.

Prospective evaluation of 68Ga-DOTA-NOC PET-CT in patients with recurrent medullary thyroid carcinoma: comparison with 18F-FDG PET-CT.

ObjectiveTo prospectively evaluate the role of 68Ga-labelled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-NaI3-octreotide (68Ga-DOTA-NOC) PET-CT in patients with recurrent medullary thyroid carcinoma (MTC) and compare the same with 18F-fluorodeoxyglucose (18F-FDG) PET-CT. Materials and methodsFifty-two consecutive patients with recurrent MTC based on raised serum calcitonin levels underwent 68Ga-DOTA-NOC PET-CT. In addition, 41 patients also underwent 18F-FDG PET-CT. PET-CT images were evaluated by two experienced nuclear medicine physicians both qualitatively and quantitatively (standardized uptake value). Histopathology (when available), correlation with conventional imaging modalities (ultrasonography/CT/MRI) and subsequent clinical/imaging follow-up were used as reference standard. Serum calcitonin levels were correlated with findings of PET-CT. ResultsOverall, 68Ga-DOTA-NOC PET-CT showed a sensitivity of 80.7% [95% confidence interval (CI) 67.4–90.3] and a positive predictive value of 100% (95% CI 91.5–100) for detecting recurrent MTC. When both were available (n=41), 68Ga-DOTA-NOC PET-CT proved superior to 18F-FDG PET-CT with a higher sensitivity (75.61 vs. 63.4%). However, the difference was statistically not significant (P=0.179). 68Ga-DOTA-NOC PET-CT was superior to 18F-FDG PET-CT for detecting recurrence in cervical lymph nodes (P<0.001). Both modalities were concordant in 75% of cases. No significant cut-off level of calcitonin could be derived for either 68Ga-DOTA-NOC or 18F-FDG PET-CT. ConclusionBoth 68Ga-DOTA-NOC PET-CT and 18F-FDG PET-CT are able to localize disease recurrence in patients with MTC, and their role appears to be complementary for this purpose.

Preoperative characterization of indeterminate large adrenal masses with dual tracer PET-CT using fluorine-18 fluorodeoxyglucose and gallium-68-DOTANOC: initial results.

PURPOSE We aimed to evaluate the usefulness of dual tracer positron emission tomography-computed tomography (PET-CT) with flourine-18 fluorodeoxyglucose (18F-FDG) and gallium-68 [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-NaI3-octreotide (68Ga-DOTANOC) in preoperative characterization of large indeterminate adrenal masses. MATERIALS AND METHODS Ten patients (four males, six females; median age, 35 years) with indeterminate, large (≥4 cm) adrenal masses were included in this prospective study. All patients underwent both 18F-FDG PET-CT and 68Ga-DOTANOC PET-CT within one week. Images were evaluated both visually and semi-quantitatively, with standardized uptake value (SUVmax) and SUVratio (SUVmax) of tumor/SUVmax) of mediastinum). Based on differential uptake pattern on 18F-FDG and 68Ga-DOTANOC, lesions were classified as cortical (18F-FDG>68Ga-DOTANOC), medullary (68Ga-DOTANOC>18F-FDG), or indeterminate (18F-FDG=68Ga-DOTANOC). Histopathology was taken as reference standard. Receiver operating characteristic (ROC) analysis was performed to find a cut-off of SUVmax) and SUVratio to differentiate cortical and medullary lesions. RESULTS On histopathology, eight lesions were adrenocortical carcinomas, one was benign pheochromocytoma, and one was malignant pheochromocytoma. Visually, 18F-FDG PET-CT was positive in all ten lesions, while 68Ga-DOTANOC PET-CT was positive in two, both of which were pheochromocytomas. On SUVmax) based analysis, nine lesions were cortical and one was medullary. On ROC analysis, a SUVmax) cut-off of > 2.3 was obtained for 18F-FDG PET-CT and 3.6 for 68Ga-DOTANOC PET-CT for differentiating adrenal cortical and medullary lesions. The cut-off for SUVratio was 4.5 on 18F-FDG PET-CT and 11.1 on 68Ga-DOTANOC PET-CT. CONCLUSION These preliminary results demonstrate that dual tracer PET-CT using 18F-FDG and 68Ga-DOTANOC could be informative in the preoperative characterization of large indeterminate adrenal masses.