Contribution of CT to treatment planning in patients with GIST

Gastrointestinal stromal tumors: relationship between preoperative CT features and pathologic risk stratification

OBJECTIVE

To investigate a relationship between contrast-enhanced computed tomography (CECT) features of gastrointestinal stromal tumors (GISTs) and risk of relapse according to Miettinen stratified risk classifications.

METHODS

After ethical committee approval, a retrospective analysis was conducted on the preoperative CECT of patients with pathologically proven GIST undergoing surgery between June 2009 and December 2019. Chi-square analysis was used to evaluate the correlation between Miettinen stratified risk categories and the following imaging features: tumor size and location, growth pattern, margins, type and degree of contrast enhancement, presence of calcifications, necrosis, signs of ulceration/fistulation, internal hemorrhagic foci, enlarged feeding or draining vessels (EFDV), ascites, peritoneal implants, lymphadenopathy, or metastasis.

RESULTS

A total of 54 patients (mean age 65 ± 11, 29 men) were included in the study with a total of 56 GISTs. Necrosis, ulceration/fistulation, hemorrhage, margins, enlarged vessels, type of contrast enhancement, and metastasis turned out to be associated with Miettinen risk categories (p < 0.005). Logistic regression analysis identified the presence of necrosis and EFDV as predictors of pathologic risk of relapse (overall accuracy of 89.3%).

CONCLUSION

Preoperative CECT may be helpful in predicting pathologic risk categories of GISTs, as determined by the Miettinen classification system.

Gastrointestinal stromal tumors (GIST): a proposal of a "CT-based predictive model of Miettinen index" in predicting the risk of malignancy

PURPOSE

To identify the predictors of malignancy on CT for the evaluation of gastrointestinal stromal tumors (GIST) by correlating CT findings with the mitotic index in order to propose a "CT-based predictive model of Miettinen index."

METHODS

One radiologist and one resident in radiology with 14- and 4-year experience in oncological field reviewed the CT findings of 42 patients by consensus, with respect to lesion site, size, contour, tumor growth pattern, enhancing pattern, degree of enhancement of tumor, percentage of tumor necrosis, mesenteric fat infiltration, ulceration, calcification, regional lymphadenopathy, direct invasion to adjacent organs, and distant metastasis. All parameters were correlated with the mitotic index evaluated at histopathological analysis following surgery. Normality of variables was evaluated using Shapiro-Wilk test. Pearson's correlation test was used to assess the interaction between variables. The diagnostic accuracy percentage of tumor necrosis was measured by receiver operating characteristic (ROC) analysis for detecting whether the number of mitosis per 50 high-power fields was > 5.

RESULTS

A significant statistical correlation was found between percentage of tumor necrosis and the mitotic index (p < 0.005), dimension, and location of the tumor.

CONCLUSION

CT could be an accurate technique in the prediction of malignancy of GIST in a CT risk assessment system, based on the location of the tumor, its size, and the percentage of tumor necrosis.

Risk stratification in GIST: shape quantification with CT is a predictive factor

Background

Tumor shape is strongly associated with some tumor’s genomic subtypes and patient outcomes. Our purpose is to find the relationship between risk stratification and the shape of GISTs.

Methods

A total of 101 patients with primary GISTs were confirmed by pathology and immunohistochemistry and underwent enhanced CT examination. All lesions’ pathologic sizes were 1 to 10 cm. Points A and B were the extremities of the longest diameter (LD) of the tumor and points C and D the extremities of the small axis, which was the longest diameter perpendicular to AB. The four angles of the quadrangle ABCD were measured and each angle named by its summit (A, B, C, D). For regular lesions, we took angles A and B as big angle (BiA) and small angle (SmA). For irregular lesions, we compared A/B ratio and D/C ratio and selected the larger ratio for analysis. The chi-square test, t test, ROC analysis, and hierarchical or binary logistic regression analysis were used to analyze the data.

Results

The BiA/SmA ratio was an independent predictor for risk level of GISTs (p = 0.019). With threshold of BiA at 90.5°, BiA/SmA ratio at 1.35 and LD at 6.15 cm, the sensitivities for high-risk GISTs were 82.4%, 85.3%, and 83.8%, respectively; the specificities were 87.1%, 71%, and 77.4%, respectively; and the AUCs were 0.852, 0.818, and 0.844, respectively. LD could not effectively distinguish between intermediate-risk and high-risk GISTs, but BiA could (p < 0.05). Shape and Ki-67 were independent predictors of the mitotic value (p = 0.036 and p < 0.001, respectively), and the accuracy was 87.8%.

Conclusions

Quantifying tumor shape has better predictive efficacy than LD in predicting the risk level and mitotic value of GISTs, especially for high-risk grading and mitotic value > 5/50HPF.

Key Points

• The BiA/SmA ratio was an independent predictor affecting the risk level of GISTs. LD could not effectively distinguish between intermediate-risk and high-risk GISTs, but BiA could.

• Shape and Ki-67 were independent predictors of the mitotic value.

• The method for quantifying the tumor shape has better predictive efficacy than LD in predicting the risk level and mitotic value of GISTs.

The roles of CT and EUS in the preoperative evaluation of gastric gastrointestinal stromal tumors larger than 2 cm

OBJECTIVE

This study aimed to investigate the endoscopic ultrasound (EUS) and computed tomography (CT) features of gastric gastrointestinal stromal tumors (GISTs) for assessing potential malignancy and prognosis.

METHODS

Fifty consecutive patients with primary gastric GISTs larger than 2 cm were retrospectively enrolled in this study. The association of CT and EUS features with malignancy was analyzed using univariate and stepwise logistic regression method. The agreement between EUS/CT lesion size and pathologic tumor size was analyzed by calculating the intraclass correlation coefficient (ICC) value, and the association of imaging features with mitotic counts was further analyzed using univariate analysis. The Kaplan-Meier method and Cox proportional hazards models were used to assess the value of imaging features for predicting the prognosis of GIST patients.

RESULTS

Tumor size > 5 cm and an exophytic/mixed growth pattern on CT as well as tumor size > 5 cm and the presence of cystic spaces on EUS were independent predictors of highly malignant GISTs (all p < 0.05). The ICC values of CT/EUS lesion size relative to pathologic tumor size showed very good reliability (0.853 for EUS and 0.831 for CT). Only tumor shape and growth pattern on CT were significant for predicting mitotic index (both p < 0.05). Direct organ invasion on CT (p = 0.036; hazard ratio [HR] = 11.891) and serosal invasion on EUS (p = 0.015; HR = 8.223) were independent adverse prognostic factors.

CONCLUSIONS

CT features may be more useful than EUS features for predicting tumor mitotic index. In addition, preoperative imaging features can help predict the prognosis of gastric GISTs.

KEY POINTS

• Both CT and EUS features can be used for risk stratification of gastric GISTs larger than 2 cm. • CT features performed better than EUS features for predicting tumor mitotic index. • Preoperative imaging features can help predict the prognosis of gastric GISTs.

A correlation research of Ki67 index, CT features, and risk stratification in gastrointestinal stromal tumor

Background and Objectives

Recurrence and metastasis are the most important factors affecting the quality of life and survival rate of patients with gastrointestinal stromal tumors (GISTs). Accurate preoperative determination of the malignant degree of GISTs and the development of a reasonable treatment plan can effectively reduce the recurrence rate. CT is currently considered the preferred imaging modality for initial assessment. Until now, there have only been a few studies investigating the relationship between CT features and recurrence of GISTs. However, the value of CT features in prognostic assessment is still unclear. In this study, we attempted to investigate the prognostic significance of CT features and the Ki67 index in GISTs.

Methods

We retrospectively analyzed the clinicopathological and imaging data for 151 patients with a histopathological diagnosis of GIST who had received contrast‐enhanced CT examination and surgical resection at XinHua Hospital from October 2008 to December 2015 or Sir Run Run Shaw Hospital in 2017. Then, we explored the correlation among CT features, the Ki67 index, and risk stratification of GISTs. The correlation among CT features, the Ki67 index, and risk stratification was mainly analyzed using the Spearman rank correlation.

Results

The incidence of high‐risk disease or metastasis was clearly higher in the group with Ki67 > 5% than that in the group with Ki67 ≤ 5% (P < 0.001). The Ki67 index was positively correlated with risk stratification (r = 0.558) or mitotic index (r = 0.619). CT imaging features including size, contour, and margin of the tumor were associated with the Ki67 index (r = 0.332, 0.333, and 0.302, respectively). The multivariate logistic regression analysis revealed that the tumor size [P = 0.043 Exp (B) = 1.150] and the presence of ulceration [P = 0.011, Exp (B) = 3.669] were effective variables in distinguishing between the groups with Ki67 ≤ 5% and >5%. The presence of necrosis or cystic degeneration, tumor contour, tumor margin, and pattern of enhancement were associated with risk stratification (r = 0.530, 0.501, 0.419, and 0.447, respectively).

Conclusions

Our findings suggest that the Ki67 index is an effective complementation in predicting the prognosis of GISTs, and CT features including size, contour, and margin of the tumor, presence of necrosis or cystic degeneration, and pattern of enhancement provide evidence to support the importance of preoperative assessment.

Tomographic findings of gastric gastrointestinal stromal tumor and correlation with the mitotic index

CONTEXT

Gastrointestinal stromal tumors are uncommon abdominal neoplasms and can affect any portion of the gastrointestinal tract.

OBJECTIVES

Describe the tomographic findings of the gastrointestinal stromal tumor of gastric origin, correlating it with the mitotic index.

METHODS

Twenty-one patients were selected within the period of January 2000 and 2008, with histopathological and immunohistochemical diagnosis of gastric gastrointestinal stromal tumors, who presented computed tomography done before the treatment. The tomographic variables analyzed were lesion topography, dimensions, contours, morphology, pattern and intensity enhancement through venous contrast, growth pattern, invasion of adjacent organs, presence of ulceration, fistula, calcifications, infiltration of mesenteric fat, lymphadenopathy and metastasis. The mitotic index was determined through optic microscopy, counting the number of mitosis figures in 50 high power fields.

RESULTS

The tumors were located in the body (66.7%) or gastric fundus (33.3%), with dimensions varying between 4.2 and 21.2 cm (average of 10.5 cm). The growth was predominantly extraluminal (47.6%) or intra/extra luminal (28.6%). The enhancement by venous contrast was heterogeneous in 66.7%. The statistical analysis showed that irregular morphology (P = 0.027) and infiltration of mesenteric fat (P = 0.012) presented correlation with the high mitotic index.

CONCLUSIONS

In the present study, most part of the tumors were located in the gastric body, with average size of 10.5 cm, presenting central hypo dense area, heterogeneous enhancement through contrast and predominantly extra luminal growth. Irregular morphology and infiltration of mesenteric fat present statistical correlation with high mitotic level.

Rectal hemangiopericytoma in a 37-year-old woman: a case report and review of the literature

Introduction

Hemangiopericytoma is an uncommon perivascular tumor. Rectal Hemangiopericytomas are extremely rare. To the best of our knowledge, only two cases have been reported in the literature.

Case presentation

We report the case of a 37-year-old Asian woman with an Hemangiopericytoma rising from the anterior wall of her rectum. Abdominopelvic computed tomography showed a 7.4 cm solid mass between her uterus and her rectum. Heterogeneous gradual enhancement after intravenous injection of contrast material was noted with several tortuous vessels around her tumor. Intra-operative findings indicated a capsule and well-circumscribed solid tumor connecting with the anterior wall of her rectum by a small pedicle. With immunohistochemical stains, her tumor cells reacted positive for Bcl-2, CD34, and ki67 and negative for CD10, CD117, S100, and Desmin. Follow-up computed tomography scans have shown no tumor recurrence or metastasis signs.

Conclusions

Rectal Hemangiopericytoma is a rare tumor with non-specific imaging findings. Hemangiopericytomas should be included in the differential list when a massive tumor with heterogeneously gradual enhancement in the regions of the rectum is encountered.

Application value of imaging methods and their progress in the diagnosis and treatment of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are a kind of mesenchymal tumors that originate from the submucosal layer of the gastrointestinal tract and show an exophytic growth pattern. CT and MRI are useful adjuncts in determining the site of origin of large GISTs and in assessing involvement of adjacent organs. GISTs can be easily differentiated from adenocarcinomas, lymphomas, ectopic pancreas, cystic lesions and lypomas. However, current imaging techniques are practically unable to distinguish GISTs from other mesenchymal tumors. Signs of malignant behavior of GISTs, which can be clearly presented on pre-operative CT or MRI, include liver metastasis, GI wall infiltration, large volume, irregular surface, ill-defined margins, inhomogeneous enhancement and peritoneal spread. CT, MRI and positron emission computed tomography (PET-CT) have been effective methods in assessment of response to Gleevec treatment of GISTs, however, the standard is ought to be improved.