Traditionally, the response to cancer treatment in solid tumors is evaluated by subsequent clinical or radiological assessments, and is defined as a significant etc decrease in the measurable tumor dimensions. A reduction in the viable tumor cell fraction, however, does not always result in a volume reduction, since tumor tissue can be replaced by necrotic or fibrotic tissue, and morphological images are often unable to differentiate between these different tissue types. In recent years, metabolic imaging with positron emission tomography (PET) has become increasingly important in cancer management. Although the performances of PET and CT are comparable in terms of the process of staging before the initiation of imatinib therapy, PET can evaluate the tumor response as early as 1 week after the start of treatment, preceding the CT response by several weeks (14).

Treatment-induced changes resulting in tumor cell death or growth arrest should therefore result in a subsequent reduction in glucose uptake, making this technique a sensitive and early marker for response evaluation. There are several limitations to this study. First, this was a retrospective review of cases collected over a number of years for which CT scans were performed irregularly, depending on the condition of the patients. Second, unenhanced images were not obtained in all patients, and it is unclear whether or not any subtle enhancement changes are present in the metastatic lesions. Third, we did not provide any pathologic correlation in any of the cases.

Pathologic correlation with the radiologic findings for metastatic lesions is helpful for clinicians as well as for radiologists. In conclusion, after treatment with imatinib, responsive intra-abdominal extra-hepatic metastases of gastrointestinal stromal tumors appear as well-defined cystic lesions on contrast-enhanced CT. These metastases become smaller and resemble ascites, but may be detected for a long time on the follow-up CT scans. Footnotes This study was supported in part by the 2003 BK21 Project for Medicine, Dentistry and Pharmacy.
Chronic hepatitis C infection affects nearly 170 million people worldwide, and it is the most common indication for liver transplantation.1-3 Between 20 and 30% of infected individuals will eventually go on to develop cirrhosis and its sequelae.

1-3 Unfortunately, even in developed countries, deaths due to hepatitis C are increasing because of inadequate detection and treatment.4-6 In a high endemic area of HBV infection, chronic hepatitis C may be overlooked until the disease has progressed significantly. In Korea, which is a high endemic area of HBV infection, about 50-90 thousand people are chronically infected with HCV, and at least 10-17% of hepatocellular carcinoma (HCC) cases are probably attributable Batimastat to HCV infection.