Correlation between Computed Tomography and Pathological Findings of Gastrointestinal Stromal Tumors Treated with Imatinib Mesylate.

Purpose: To evaluate the correlation between pathological and computed tomography (CT) findings of gastrointestinal stromal tumors (GISTs) after imatinib mesylate (imatinib) treatment. Materials and Methods: Twenty-six patients with GIST (17 men, 9 women; mean age, 56 years) who underwent treatment with imatinib and who were registered at our institution were included. Eight patients had primary and 18 had metastatic tumors. The correlation between CT and pathological findings was evaluated for all 26 tumors, which were resected after imatinib treatment. Results: The mean size change in the tumors after imatinib treatment was -1.4 cm (range, -7.8-2.5 cm). A reduction in tumor CT attenuation value was observed after imatinib treatment (mean, 29.1 Hounsfield units) in 20 of 26 tumors. Reduced attenuation was associated with non-tumorous pathological findings, including cystic degeneration (6/20), hemorrhagic necrosis (6/20), hyaline degeneration (6/20), and combined pathology without a viable portion (2/20). Of six tumors showing increased attenuation values after treatment, four (66.7%) showed an abundant viable portion. The increase in tumor size was not associated with the presence of a viable portion in any tumor. Conclusion: CT attenuation changes in GISTs may adequately reflect the pathological findings in GISTs after imatinib treatment. [ABSTRACT FROM AUTHOR]