Clinical usefulness of 18F-FDG PET/CT in the restaging of esophageal cancer after surgical resection and radiotherapy.

AIM: To evaluate the clinical usefulness of (18)F-fluorodeoxyglucose positron emission and computed tomography ((18)F-FDG PET/CT) in restaging of esophageal cancer after surgical resection and radiotherapy. METHODS: Between January 2007 and Aug 2008, twenty histopathologically diagnosed esophageal cancer patients underwent 25 PET/CT scans (three patients had two scans and one patient had three scans) for restaging after surgical resection and radiotherapy. The standard reference for tumor recurrence was histopathologic confirmation or clinical follow-up for at least ten months after (18)F-FDG PET/CT examinations. RESULTS: Tumor recurrence was confirmed histopathologically in seven of the 20 patients (35%) and by clinical and radiological follow-up in 13 (65%). (18)F-FDG PET/CT was positive in 14 patients (68.4%) and negative in six (31.6%). (18)F-FDG PET/CT was true positive in 11 patients, false positive in three and true negative in six. Overall, the accuracy of (18)F-FDG PET/CT was 85%, negative predictive value (NPV) was 100%, and positive predictive value (PPV) was 78.6%. The three false positive PET/CT findings comprised chronic inflammation of mediastinal lymph nodes (n = 2) and anastomosis inflammation (n = 1). PET/CT demonstrated distant metastasis in 10 patients. (18)F-FDG PET/CT imaging-guided salvage treatment in nine patients was performed. Treatment regimens were changed in 12 (60%) patients after introducing (18)F-FDG PET/CT into their conventional post-treatment follow-up program. CONCLUSION: Whole body (18)F-FDG PET/CT is effective in detecting relapse of esophageal cancer after surgical resection and radiotherapy. It could also have important clinical impact on the management of esophageal cancer, influencing both clinical restaging and salvage treatment of patients.

Clinical role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in post-operative follow up of gastric cancer: initial results.

AIM: To evaluate the clinical role of (18)F-fluorodeoxyglucose positron emission and computed tomography ((18)F-FDG PET/CT) in detection of gastric cancer recurrence after initial surgical resection. METHODS: In the period from January 2007 to May 2008, 23 patients who had previous surgical resection of histopathologically diagnosed gastric cancer underwent a total of 25 (18)F-FDG PET/CT scans as follow-up visits in our center. The standard of reference for tumor recurrence consisted of histopathologic confirmation or clinical follow-up information for at least 5 mo after PET/CT examinations. RESULTS: PET/CT was positive in 14 patients (61%) and negative in 9 (39%). When correlated with final diagnosis, which was confirmed by histopathologic evidence of tumor recurrence in 8 of the 23 patients (35%) and by clinical follow-up in 15 (65%), PET/CT was true positive in 12 patients, false positive in 2, true negative in 8 and false negative in 2. Overall, the accuracy of PET/CT was 82.6%, the negative predictive value (NPV) was 77.7%, and the positive predictive value (PPV) was 85.7%. The 2 false positive PET/CT findings were actually chronic inflammatory tissue lesions. For the two patients with false negative PET/CT, the final diagnosis was recurrence of mucinous adenocarcinoma in the anastomosis in one patient and abdominal wall metastasis in the other. Importantly, PET/CT revealed true-positive findings in 11 (47.8%) patients who had negative or no definite findings by CT. PET/CT revealed extra-abdominal metastases in 7 patients and additional esophageal carcinoma in one patient. Clinical treatment decisions were changed in 7 (30.4%) patients after introducing PET/CT into their conventional post-operative follow-up program. CONCLUSION: Whole body (18)F-FDG PET/CT was highly effective in discriminating true recurrence in post-operative patients with gastric cancer and had important impacts on clinical decisions in a considerable portion of patients.

Highly metabolic thrombus of the portal vein: 18F fluorodeoxyglucose positron emission tomography/computer tomography demonstration and clinical significance in hepatocellular carcinoma.

AIM: To assess the ability of (18)F-fluorodeoxyglucose positron emission tomography/computer tomography ((18)F-FDG PET/CT) to differentiate between benign and malignant portal vein thrombosis in hepatocellular carcinoma (HCC) patients. METHODS: Five consecutive patients who had HBV cirrhosis, biopsy-proven HCC, and thrombosis of the main portal vein and/or left/right portal vein on ultrasound (US), computer tomography (CT) or magnetic resonance imaging (MRI) were studied with (18)F-FDG PET/CT. The presence or absence of a highly metabolic thrombus on (18)F-FDG PET/CT was considered diagnostic for malignant or benign portal vein thrombosis, respectively. All patients were followed-up monthly with US, CT or MRI. Shrinkage of the thrombus or recanalization of the vessels on US, CT or MRI during follow-up was considered to be definitive evidence of the benign nature of the thrombosis, whereas enlargement of the thrombus, disruption of the vessel wall, and parenchymal infiltration over follow-up were considered to be consistent with malignancy. (18)F-FDG PET/CT, and US, CT or MRI results were compared. RESULTS: Follow-up (1 to 10 mo) showed signs of malignant thrombosis in 4 of the 5 patients. US, CT or MRI produced a true-positive result for malignancy in 4 of the patients, and a false-positive result in 1. (18)F-FDG PET/CT showed a highly metabolic thrombus in 4 of the 5 patients. (18)F-FDG PET/CT achieved a true-positive result in all 4 of these patients, and a true-negative result in the other patient. No false-positive result was observed using (18)F-FDG PET/CT. CONCLUSION: (18)F-FDG PET/CT may be helpful in discriminating between benign and malignant portal vein thrombi. Patients may benefit from (18)F-FDG PET/CT when portal vein thrombi can not be diagnosed exactly by US, CT or MRI.

Positron emission tomography/computer tomography in guidance of extrahepatic hepatocellular carcinoma metastasis management.

Hepatocellular carcinoma (HCC) is one of the most common primary cancers in the world. Surgery is the gold standard for treatment of patients with HCC. Recurrence and metastasis are the major obstacles to further improve the prognosis of HCC. Most recurrences are intrahepatic. However, 30% of the recurrences are extrahepatic. The role of resection in intrahepatic recurrences is widely accepted. The role of resection in extrahepatic HCC recurrence and metastasis is not well established. 18F fluorodeoxyglucose (18F-FDG) positron emission tomography/computer tomography (PET/CT) is useful in detecting distant metastasis from a variety of malignancies and shows superior accuracy to conventional imaging modalities in identification of intrahepatic and extrahepatic metastasis. We present one patient with one new isolated omental lymph node metastasis, who had a history of huge HCC resected six years ago. The metastatic focus was identified with 18 F-FDG PET/CT and resected. The follow-up revealed good prognosis with a long-term survival potential after resection of the omental lymphatic metastasis.

Positron emission tomography/computed tomography with (18)F-fluorodeoxyglucose identifies tumor growth or thrombosis in the portal vein with hepatocellular carcinoma.

Patients suffering from hepatocellular carcinoma (HCC) with tumor thrombus in the portal vein generally have a poor prognosis. Portal vein tumor thrombus must be distinguished from portal vein blood thrombus, and this identification plays a very important role in management of HCC. Conventional imaging modalities have limitations in discrimination of portal vein tumor thrombus. The application of positron emission tomography (PET) with (18)F-fluorodeoxyglucose ((18)F-FDG) for discrimination between tumor extension and blood thrombus has been reported in few cases of HCC, while portal tumor thrombosis and portal vein clot identified by (18)F-FDG PET/CT in HCC patients has not been reported so far. We present two HCC cases, one with portal vein tumor thrombus and one thrombosis who were identified with (18)F-FDG PET/CT. This report illustrates the complimentary value of combining the morphological and functional imaging in achieving a correct diagnosis in such clinical situations.