Gastrointestinal Stromal Tumor (GIST): Computed
Tomographic Features and Correlation of
CT Findings with Histologic Grade
Siriporn Pinaikul MD*, Piyanoot Woodtichartpreecha MD*,
Samornmas Kanngurn MD**, Sombat Leelakiatpaiboon MSc***
Affiliation :
* Division of Diagnostic Imaging, Department of Radiology, Faculty of Medicine,
Prince of Songkla University, Songkhla, Thailand
** Department of Pathology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand
*** Division of Radiotherapy, Department of Radiology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand
Objective : To characterize the CT features and to identify predictors of malignancy from CT of GISTs.
Material and Method: A retrospective review of CT images of 50 patients with pathologically and immunohistochemically
proven GISTs was done by two radiologists and final interpretations were reached by consensus. Images were evaluated
for site, size, contour, boundary, growth pattern, enhancement pattern, degree of enhancement, necrosis, calcification,
ulceration, perilesional fat stranding, evidence of bowel obstruction, and signs of malignancy. Categorical variables were
compared using Fisher’s exact test and continuous variables used the t-test. Univariate and multivariate logistic regression
models were used to identify significant predictors of a high mitotic rate.
Results : Of the 50 patients, the most common location of GISTs was stomach (62%) The mean size was 10.2 cm (SD 5.2 cm).
The contour was lobulated in 84%. The boundary was smooth in 84%. The growth pattern was exophytic in 68%. Most of
tumors had heterogeneous density on post-contrast images (88%). Necrosis (84%), calcification (14%), ulceration (40%),
perilesional fat stranding (44%), and bowel obstruction (2%) were present in the tumors. The CT signs of malignancy found
were adjacent organ invasion (18%), ascites (18%), lymphadenopathy (6%), liver metastasis (20%), and peritoneal seeding
(16%). Necrosis and peritoneal seeding were statistically significant independent predictors for high mitotic GISTs in
multivariate logistic regression (p<0.05). The probability of a high mitotic rate was 1 (95% CI, 0.40-1.00) in the presence
of both necrosis and peritoneal seeding.
Conclusion : The stomach was the most common site of GIST. The CT features of GIST were lobulated, smooth tumor
margins, exophytic growth pattern, and heterogeneous enhancement on post-contrast CT images. Presence of both necrosis
and peritoneal seeding were found to be a significant predictor of high mitotic rate of GISTs. The probability of a high
mitotic rate was 1 (95% CI, 0.40-1.00).
Keywords : Computed tomography, Gastrointestinal stromal tumor (GIST)
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