Positron-emission tomography with fluorine-18-fluoro-2-deoxy-D-glucose for gallbladder cancer diagnosis

Distinguishing benign from malignant gallbladder wall thickening using FDG-PET

OBJECTIVE

Because thickening of the gallbladder wall is observed not only in patients with gallbladder cancer but also in those with benign diseases such as chronic cholecystitis and gallbladder adenomyosis, it is difficult to distinguish between benign and malignant gallbladder wall thickening by conventional techniques of diagnostic imaging such as computed tomography (CT), magnetic resonance imaging (MRI), and abdominal ultrasonography (US). In the present study, we attempted to distinguish between benign and malignant gallbladder wall thickening by means of fluorine-18-fluorodeoxyglucose (FDG)-Positron emission tomography (PET).

METHODS

FDG-PET was performed in 12 patients with gallbladder wall thickening detected by CT or US, to determine whether it was benign or malignant. Emission scans were taken, beginning 45 minutes after intravenous administration of FDG, and SUV was calculated as an indicator of glucose metabolism.

RESULTS

Of the 12 patients, 4 showed positive uptake of FDG in the gallbladder wall. Of these 4 patients, 3 had gallbladder cancer. The remaining one, who had chronic cholecystitis, had false-positive findings. The other 8 patients had negative uptake of FDG in the gallbladder wall. Two of these 8 underwent surgical resection, which yielded a diagnosis of chronic cholecystitis. The other 6 patients exhibited no sign of gallbladder malignancy and have been followed without active treatment.

CONCLUSIONS

FDG-PET appears able to distinguish between benign and malignant gallbladder wall thickening.

Fluorine-18 fluorodeoxyglucose PET in the preoperative staging of colorectal cancer

INTRODUCTION

In patients with colorectal cancer (CC), preoperative evaluation and staging should focus on techniques that might alter the preoperative or intraoperative surgical plan. Conventional imaging methods (CT, MRI) have low accuracy for identifying the depth of tumour infiltration and have limited ability to detect regional lymph node involvement. The aim of this study was to evaluate the utility of FDG-PET in the initial staging of patients with CC in comparison with conventional staging methods and to determine its impact on therapeutic management.

METHODS

One hundred and four patients with a diagnosis of CC (53 males and 51 females; mean age 66.76+/-12.36 years), selected prospectively, were studied for staging using a standard procedure (CT) and FDG-PET. When possible, the reference method was histology.

RESULTS

In 14 patients, surgery was contraindicated by FDG-PET owing to the extent of disease (only 6/14 suspected by CT). FDG-PET revealed four synchronous tumours. For N staging, both procedures showed a relatively high specificity but a low diagnostic accuracy (PET 56%, CT 60%) and sensitivity (PET 21%, CT 25%). For M assessment, diagnostic accuracy was 92% for FDG-PET and 87% for CT. FDG-PET results led to modification of the therapy approach in 50% of patients with unresectable disease. FDG-PET findings were important, revealing unknown disease in 19.2%, changing the staging in 13.46% and modifying the scope of surgery in 11.54% (with a change in the therapeutic approach in 17.85% of those patients with rectal cancer).

CONCLUSION

Compared with conventional techniques, FDG-PET appears to be useful in pre-surgical staging of CC, revealing unsuspected disease and impacting on the treatment approach.

Gallbladder tuberculosis: False-positive PET diagnosis of gallbladder cancer

Gallbladder tuberculosis (GT) is an extremely rare disease, and very few cases have been reported in the literature. The first case of GT was described in 1870 by Gaucher. A correct preoperative diagnosis of GT is unusual, and it is frequently confused with various gallbladder diseases. We present a new case of a patient who underwent surgery with the preoperative diagnosis of gallbladder cancer after a false positive positron emission tomography scan in the diagnostic work-up.

Impact of integrated positron emission tomography and computed tomography on staging and management of gallbladder cancer and cholangiocarcinoma

BACKGROUND/AIMS

(1) To evaluate the diagnostic value of integrated positron emission and computed tomography (PET/CT) in comparison with contrast-enhanced CT (ceCT) to detect biliary tract tumors and associated distant and regional lymph node metastases and (2) to evaluate the impact of PET/CT on therapy management.

METHODS

From January 2001 to March 2005, each patient who was treated for a malignancy of the biliary tract underwent PET/CT examination in addition to the standard work-up imaging. Data were prospectively collected and analyzed in comparison with ceCT.

RESULTS

Sixty-one patients with malignancies of the biliary tract were included into the study. Diagnosis was proven in all patients either by histology or cytology. PET/CT detected all gallbladder cancers (n=14). PET/CT and ceCT provided a comparable accuracy for the primary intra- (n=14) and extra-hepatic cholangiocarcinomas (n=33). All distant metastases (12/12) were detected by PET/CT, but only 3/12 by ceCT (p<0.001). Regional lymph node metastases were detected by PET/CT and ceCT in only 12% vs. 24%. PET/CT findings resulted in a change of management in 17% of patients deemed resectable after standard work-up.

CONCLUSIONS

PET/CT is particularly valuable in detecting unsuspected distant metastases which are not diagnosed by standard imaging. Thus, PET/CT staging has an important impact on selection of adequate therapy.

Application of modern imaging methods in diagnosis of gallbladder cancer

The poor prognosis of gallbladder cancer (GBC) is related to its dissemination capacity and usually late diagnosis due to its non-specific clinical appearance. Recent improvements in hepatobiliary surgery have underlined the importance of an early specific diagnosis, which requires a multidisciplinary approach and, when possible, specialized equipment. The first step in an early diagnosis is to identify patients in the appropriate epidemiological setting (e.g., incidental finding, chronic cholecystitis) for the correct interpretation of test results. It is desirable to enhance the sensitivity of the initial ultrasound (US) examination by use of the appropriate technology in skilled specialist hands. When GBC is suggested by US findings, FDG-PET can be considered complementary to establish the benign/malignant nature of the lesion and to obtain a primary staging study. If GBC is confirmed, thin slice spiral CT can contribute valuable information on local spread. In this regard, recent hybrid PET-CT systems provide structural and functional information simultaneously and may offer early and accurate T, N, and M staging with an improved specificity.

Biliary tract cancers: current concepts and controversies

Biliary tract cancer, which consists of gall bladder cancer and cholangio-carcinoma, presents many challenges to practising physicians. It is a relatively rare cancer that often causes a diagnostic dilemma, as its presentation may be similar to that of non-malignant conditions. In many cases, histological or cytological confirmation of a cancer diagnosis is not possible preoperatively. The management of this disease is also complex due to a morbid patient population and limited data on the optimal therapeutic approach. Surgery remains the mainstay of treatment, although the extent of resection required is still debated. The role of adjuvant therapy is also controversial, but a combined modality approach appears to be beneficial in patients with a high risk of recurrence, such as those with node positive tumors or positive resection margins. When surgery is not possible, the prognosis of patients with biliary tract cancer is very poor. In unresectable patients, the combination of chemotherapy and radiotherapy can result in a prolonged survival for some patients. In the palliative setting, biliary stenting and other supportive measures can alleviate symptoms and improve survival. Gemcitabine-based combination chemotherapy may also provide successful palliation and has achieved response rates of approximately 30% and a median survival of > 15 months in one study. Ultimately, treatment decisions should be individualised and participation in clinical trials is encouraged. Further progress in the management of biliary tract cancer is anticipated using biological therapies and continued research is essential to discover the optimal treatment for this challenging disease.