Chulalongkorn Medical Journal


Background : Gastrointestinal stromal tumors (GISTs) have their specificreceptor that allows the use of specific target drug. CT scan isthe imaging technique of choice to evaluate the response ofthe tumor. There are some conflicts about CT parameter suchas size and density that confuse radiologists in the evaluation ofthe tumor response.Objective : Our objective is to evaluate CT appearances in patients withGISTs who have response after imatinib treatment by combinationof RECIST criteria and density, vascularity, solid nodule andcystic change of the tumor.Design : Retrospective studySetting : King Chulalongkorn Memorial Hospital, Thai Red Cross Society.Materials and Methods : Sixty-five tumors from 14 patients were 33 intrahepatic and 32extrahepatic lesions. All patients underwent contrast-enhancedMDCT scan in both pre-and post treatment periods. The axialimages of CT portovenous phase with 8-mm slice thicknesswere reviewed by the author and one experienced gastrointestinalradiologist, with consensus.Results : Significant decrease in size and density of overall tumors werenoted. The extrahepatic lesions had statistically significantdecrease in both size and density than intrahepatic lesions. Onpre-treatment images, solid nodules within the lesions werefound in 18 lesions (27.7%), mainly in extrahepatic lesions whiletumor vessels were found in 7 extrahepatic lesions (10.8%).There were new cystic-like lesions in the liver of 2 patients onpost-treatment images. No new solid mass was seen aftertreatment.Conclusion : Our data supports other studies on the response of GISTs toimatinib treatment. We suggest that in case of mismatchbetween size and density, size may not be reliable factor.Density, vascularity, solid nodule and cystic change maycomplement to each other in evaluation of response to treatmentin addition to size. Extrahepatic lesions display more definiteresponse in terms of size and density when compared tointrahepatic lesions.


Faculty of Medicine, Chulalongkorn University

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