Positron emission tomography thyroid incidentaloma: Is it different in Indian subcontinent.

BACKGROUND: Positron emission tomography (PET) forms an integral part in work‑up and follow‑up of various malignancies. With the increased use of PET in oncology, finding of an incidental focal thyroid uptake (incidentaloma) is not unusual and presents a diagnostic challenge. AIM: The aim of the following study is to evaluate the frequency and radio‑pathologic correlation of focal 18‑fluoro deoxyglucose uptake (FDG) on PET within the thyroid from a large series. MATERIALS AND METHODS: Retrospective review of 37,000 consecutive patients who underwent FDG‑PET at tertiary cancer center in India. Radiological, pathological, PET scan and follow‑up details were evaluated. Statistical analyzes were carried out using Mann Whitney test and Pearson correlation. RESULTS: Abnormal thyroid uptake was seen in 78 (0.2%) patients. Nearly 61 (0.16%) scans had focal and 17 (0.04%) had diffuse FDG uptake. A total of 57 patients with focal uptake were available for further evaluation. No further evaluation was done in 24 (42.1%) patients who had advanced index malignancy. Of the remaining 33 patients 26 were benign and seven were a cause for concern (four primary thyroid cancers, one follicular neoplasm with hurthle cell change and two metastatic cancers). There was no significant correlation in Standardized uptake value (SUV) max of benign and malignant lesion (P = 0.5 on Mann Whitney) or size (r = 0.087 Pearson correlation co‑efficient P = 0.667). CONCLUSION: Incidence of PET incidentaloma is low in this large cohort of Indian patients. Nearly 27% of focal incidentaloma were malignant. There was no correlation between the SUVmax, size and malignancy.

Utility of PET in unknown primary with cervical metastasis: A retrospective study.

Background: FDG-PET is recommended as an investigation in unknown primary tumors, but its definitive role and cost effectiveness are yet to be established. Aims: dditional value of FDG-PET over conventional imaging in unknown primary tumors with cervical metastasis. Setting and Design: Retrospective study in a tertiary level oncology centre. Materials and Methods: A total of 112 patients were divided into three groups; 53 with conventional modalities (either computed tomography or magnetic resonance imaging) (group I), 59 with FDG-PET (group II), and group III (subgroup of group II) with both (40 patients). Statistical Analysis: Sensitivity and specificity of both conventional modality and PET were calculated. Association between neck nodes and distant metastasis was analysed using multivariate logistic regression analysis. Results: Sensitivity and specificity for conventional modalities was 92.3% and 50% and sensitivity and specificity of FDG-PET was 92.8% and 71.4%, respectively. FDG-PET detected metastasis in 52.54% of patients. Multivariate logistic regression analysis showed statistically significant association between distant metastasis and multiplicity of nodes (N2b, N2c) (P = 0.007). Among all patients with low neck nodes in group II, FDG-PET detected primaries in 12 patients, 9 of which were infraclavicular (75%). FDG-PET added information to conventional imaging in 32.5% of patients and influenced an overall change in management in 38.9% of patients. Conclusions: FDG-PET is a valuable tool influencing change of management in unknown primary with cervical metastasis. It is recommended especially in the presence of low or multiple neck nodes in view of high incidence of infraclavicular primary and distant metastasis, respectively.

Positron emission tomography / computerized tomography evaluation of primary Hodgkin's disease of liver.

Occurrence of primary Hodgkin's lymphoma (PHL) of the liver is extremely rare. We report on a case of a 60-year-old male who presented with liver mass and B-symptomatology. Hepatoma or hepatic metastasis from a gastrointestinal primary was initially suspected. Tumor markers like AFP, CEA, Total PSA, and CA-19.9 were within normal limits. Positron Emission Tomography / Computerized Tomography (PET/CT) revealed a large hepatic lesion and a nodal mass in the porta hepatis. A liver biopsy was consistent with Hodgkin's lymphoma. There was complete regression of the hepatic lesion and evidence of shrinkage of the nodal mass following four cycles of chemotherapy. 18F Fluro -de-oxy Glucose (FDG) PET / CT in this case helped in establishing a primary hepatic lymphoma by demonstrating the absence of pathologically hypermetabolic foci in any other nodes or organs. PET / CT scan is a useful adjunct to conventional imaging and histopathology, not only to establish the initial diagnosis, but also to monitor treatment response in PHL.