Role of 18F FDG PET-CT in restaging of patients with gall bladder carcinoma: - experience at a tertiary care hospital

Objectives To evaluate the diagnostic performance of contrast enhanced F-18 FDG PET/CT in restaging of gall bladder carcinoma

Methods A retrospective analysis of histopathological proven patients with gall bladder adenocarcinoma (age range 28 -80years; mean age 51.1 years; Male/ female 21/73) was done. All the patients had been treated previously (surgery, radiotherapy or chemotherapy) and referred for F-18 FDG PET/CT to rule out residual or recurrent disease. On FDG PET any abnormal tracer uptake with corresponding CECT lesion were taken as positive. Histopathological examination and clinical or imaging follow up were taken as gold standard.

Results Out of the 94 patients, 77 patients were true positive for primary disease. FDG PET/CT detected abnormal FDG uptake in 82 patients. Uptake at the primary site was detected in 32 (34%) patients and only metastatic lesions in 50(53%) patients. Out of 32 patients with primary lesions, 22 had adjacent liver involvement, 5 had adjacent bowel involvement, 2 had only regional lymph nodes, 9 only had distant lesions, 16 had both regional and distant lesions and remaining had only primary lesion. On lesion based analyses in 77 patients with distant metastases, lymph nodes, abdominal wall & peritoneal deposits, liver, lung, skeleton, adrenal and muscle metastases were noted in 26, 29, 27, 13, 7, 6 and 1 patients respectively. Additionally we also detected metachronous primaries in 8 patients and confirmed on histopathology (lung-3, pancreas, renal, thyroid, breast, lymphoma -one each). We found FDG PET/CT sensitivity, specificity, PPV, NPV and accuracy to be 95% [95% CI: 87-99], 47% [95% CI: 23-72], 89% [95% CI: 80-95], 67% [95% CI: 35-90] and 94% respectively for residual/recurrence detection (P <0.05). There was no correlation between SUVmax and patient survival (Spearman's coefficient rank correlation).

Conclusions We concluded that 18F-FDG PET/CT had high diagnostic accuracy for suspected residual/recurrent disease in gall bladder cancer patients and also useful in detection of additional metachronous second primary.