Gastrointestinal stromal tumour: 40-row multislice computed tomography findings

Is single incision laparoscopic surgery (SILS) for gastric gastrointestinal stromal tumor (GIST) dependent on the location of the tumor?

BACKGROUND

We compared the surgical outcomes of single-incision laparoscopic surgery (SILS) and conventional laparoscopic surgery (CLS) for gastric gastrointestinal stromal tumor (GIST).

METHODS

We performed single-incision gastric wedge resection on prospectively-enrolled 15 consecutive patients with gastric GIST between November 2020 and April 2022 in a single tertiary center. The early perioperative outcomes of these patients were compared to those of patients who underwent CLS. The indications did not differ from those for conventional laparoscopic procedures for gastric GIST.

RESULTS

In total, 30 patients were assigned to the SILS (n = 15) and CLS (n = 15) groups. There were no significant differences in the estimated blood loss and intraoperative blood transfusion between the SILS and CLS groups. There were no intraoperative complications or conversions to multiple-port or open surgery in the SILS group. Proximally located tumors were more commonly treated with CLS than with SILS (P = 0.045). GISTs located in the greater curvature were more commonly treated with SILS than with CLS, although the difference was not statistically significant (P = 0.08). The mean incision length in the SILS group was 4.1 cm shorter than that in the CLS group (3.2 ± 0.7 and 7.3 ± 5.2 cm, respectively, P = 0.01). The postoperative analgesic dose was significantly lower in the SILS than in the CLS group (0.4 ± 1.4 and 2.1 ± 2.3, respectively P = 0.01). Also, the duration of postoperative use of analgesic was shorter in SILS than in CLS (0.4 ± 0.7 and 2.0 ± 1.8, respectively, P = 0.01). There were no significant differences in the early postoperative complications between the groups.

CONCLUSIONS

SILS is as safe, feasible, and effective for the treatment of gastric GIST as CLS with comparable postoperative complications, pain, and cosmesis. Moreover, SILS can be considered without being affected by the type or location of the tumor.

Mesenchymal tumors of the stomach: radiologic and pathologic correlation

Mesenchymal tumors of the stomach are uncommon, with gastrointestinal stromal tumor (GIST) being the most common among them. Majority of the tumors may arise from cells of Cajal, smooth muscle cells, neural cells, totipotent stem cells, adipocytes or fibroblasts. Imaging plays an important role not only in staging but also in characterizing these tumors. Many of these tumors have characteristic imaging features. GISTs usually present as large cavitating and necrotic tumors with exophytic component. Presence of fat tissue within the tumor suggests a lipoma or a teratoma, early phase hyperenhancement indicates glomus tumor and hemangioma, and delayed contrast enhancement is seen in schwannoma. Their differentiation from epithelial tumors like carcinoma and neuroendocrine tumors is often possible based on the location (mesenchymal tumors are intramural), spread, morphological appearance and enhancement patterns. However, overlapping features exist between these tumors with imaging often being only suggestive. A biopsy is necessary for a definitive diagnosis in many cases.

Assessment of morphological CT imaging features for the prediction of risk stratification, mutations, and prognosis of gastrointestinal stromal tumors

OBJECTIVES

To investigate the correlation between CT imaging features and risk stratification of gastrointestinal stromal tumors (GISTs), prediction of mutation status, and prognosis.

METHODS

This retrospective dual-institution study included patients with pathologically proven GISTs meeting the following criteria: (i) preoperative contrast-enhanced CT performed between 2008 and 2019; (ii) no treatments before imaging; (iii) available pathological analysis. Tumor risk stratification was determined according to the National Institutes of Health (NIH) 2008 criteria. Two readers evaluated the CT features, including enhancement patterns and tumor characteristics in a blinded fashion. The differences in distribution of CT features were assessed using univariate and multivariate analyses. Survival analyses were performed by using the Cox proportional hazard model, Kaplan-Meier method, and log-rank test.

RESULTS

The final population included 88 patients (59 men and 29 women, mean age 60.5 ± 11.1 years) with 45 high-risk and 43 low-to-intermediate-risk GISTs (median size 6.3 cm). At multivariate analysis, lesion size ≥ 5 cm (OR: 10.52, p = 0.009) and enlarged feeding vessels (OR: 12.08, p = 0.040) were independently associated with the high-risk GISTs. Hyperenhancement was significantly more frequent in PDGFRα-mutated/wild-type GISTs compared to GISTs with KIT mutations (59.3% vs 23.0%, p = 0.004). Ill-defined margins were associated with shorter progression-free survival (HR 9.66) at multivariate analysis, while ill-defined margins and hemorrhage remained independently associated with shorter overall survival (HR 44.41 and HR 30.22). Inter-reader agreement ranged from fair to almost perfect (k: 0.32-0.93).

CONCLUSIONS

Morphologic contrast-enhanced CT features are significantly different depending on the risk status or mutations and may help to predict prognosis.

KEY POINTS

• Lesions size ≥ 5 cm (OR: 10.52, p = 0.009) and enlarged feeding vessels (OR: 12.08, p = 0.040) are independent predictors of high-risk GISTs. • PDGFRα-mutated/wild-type GISTs demonstrate more frequently hyperenhancement compared to GISTs with KIT mutations (59.3% vs 23.0%, p = 0.004). • Ill-defined margins (hazard ratio 9.66) were associated with shorter progression-free survival at multivariate analysis, while ill-defined margins (hazard ratio 44.41) and intralesional hemorrhage (hazard ratio 30.22) were independently associated with shorter overall survival.

Gastric Calcifying Fibrous Tumor: An Easy Misdiagnosis as Gastrointestinal Stromal Tumor-A Systemic Review

Background and Objectives: Calcifying fibrous tumor (CFT) in the stomach is extremely rare and is easily misdiagnosed as a gastrointestinal stromal tumor (GIST). This study aims to determine the best method to differentiate between gastric CFT and GIST after a systemic review and meta-analysis. Materials and Methods: A systematic search of articles using electronic databases (MEDLINE, EMBASE, and LILACS) was conducted and resulted in 162 articles with 272 CFT cases published from January 1988 to September 2019. Results: Of these cases, 272 patients, 60 patients with gastric CFT (32 men and 28 women, mean age 49.2 years) were analyzed. The mean tumor size was 2.4 cm in patients with gastric CFT. Both endoscopic ultrasound (EUS) and computed tomography (CT) findings revealed well-defined (100% vs. 77.8%), heterogeneous (100% vs. 77.8%), iso-hypoechoic (71.4% vs. 33.3%), and calcified (85.7% vs. 77.8%) lesions, respectively. The majority of patients (53.3%) were symptomatic, with the most common symptom being abdominal discomfort (55.6%). None of the patients with gastric CFT showed recurrence after treatment, and most patients received nonendoscopic treatment (56%, n = 28/50). Both age and tumor size were statistically significant in patients with gastric CFT than GIST (49.2 vs. 65.0 years and 2.4 vs. 6.0 cm; both p < 0.001). The ratio of children among patients with CFT (5%) and GIST (0.05%) was also significantly different (p = 0.037). The calcification rates of gastric CFT had significantly higher calcification rates than GIST on images of EUS and CT (85.7% vs. 3.6% and 77.8% vs. 3.6%; both p < 0.001). Conclusions: Compared with patients with GIST, patients with gastric CFT were younger, had smaller tumor size, and were symptomatic. Furthermore, gastric CFT was well-defined, heterogeneous in the third layer, and had high calcification rates on the images.

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.

New advances in radiomics of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are uncommon neoplasms of the gastrointestinal tract with peculiar clinical, genetic, and imaging characteristics. Preoperative knowledge of risk stratification and mutational status is crucial to guide the appropriate patients’ treatment. Predicting the clinical behavior and biological aggressiveness of GISTs based on conventional computed tomography (CT) and magnetic resonance imaging (MRI) evaluation is challenging, unless the lesions have already metastasized at the time of diagnosis. Radiomics is emerging as a promising tool for the quantification of lesion heterogeneity on radiological images, extracting additional data that cannot be assessed by visual analysis. Radiomics applications have been explored for the differential diagnosis of GISTs from other gastrointestinal neoplasms, risk stratification and prediction of prognosis after surgical resection, and evaluation of mutational status in GISTs. The published researches on GISTs radiomics have obtained excellent performance of derived radiomics models on CT and MRI. However, lack of standardization and differences in study methodology challenge the application of radiomics in clinical practice. The purpose of this review is to describe the new advances of radiomics applied to CT and MRI for the evaluation of gastrointestinal stromal tumors, discuss the potential clinical applications that may impact patients’ management, report limitations of current radiomics studies, and future directions.

Computed tomography-based radiomics model for discriminating the risk stratification of gastrointestinal stromal tumors

PURPOSE

The pathological risk degree of gastrointestinal stromal tumors (GISTs) has become an issue of great concern. Computed tomography (CT) is beneficial for showing adjacent tissues in detail and determining metastasis or recurrence of GISTs, but its function is still limited. Radiomics has recently shown a great potential in aiding clinical decision-making. The purpose of our study is to develop and validate CT-based radiomics models for GIST risk stratification.

METHODS

Three hundred and sixty-six patients clinically suspected of primary GISTs from January 2013 to February 2018 were retrospectively enrolled, among which data from 140 patients were eventually analyzed after exclusion. Data from patient CT images were partitioned based on the National Institutes of Health Consensus Classification, including tumor segmentation, radiomics feature extraction and selection. A radiomics model was then proposed and validated.

RESULTS

The radiomics signature demonstrated discriminative performance for advanced and nonadvanced GISTs with an area under the curve (AUC) of 0.935 [95% confidence interval (CI) 0.870-1.000] and an accuracy of 90.2% for validation cohort. The radiomics signature demonstrated favorable performance for the risk stratification of GISTs with an AUC of 0.809 (95% CI 0.777-0.841) and an accuracy of 67.5% for the validation cohort. Radiomics analysis could capture features of the four risk categories of GISTs. Meanwhile, this CT-based radiomics signature showed good diagnostic accuracy to distinguish between nonadvanced and advanced GISTs, as well as the four risk stratifications of GISTs.

CONCLUSION

Our findings highlight the potential of a quantitative radiomics analysis as a complementary tool to achieve an accurate diagnosis for GISTs.

Cross-Sectional Imaging of Small Bowel Malignancies

Small bowel malignancies are rare neoplasms, usually inaccessible to conventional endoscopy but detectable in many cases by cross-sectional imaging. Modern multidetector computed tomographies permit accurate diagnosis, complete pretreatment staging, and follow-up of these lesions. In this review, we describe the cross-sectional imaging features of the most frequent histologic subtypes of the small bowel malignancies.

The utility of pre-operative peritoneal lavage examination in serosa-invading gastric cancer patients

BACKGROUND

Peritoneal dissemination is frequently found during laparotomy in patients with serosa-invading gastric cancer. Detection of exfoliated cancer cells in abdominal lavage cytology is indicative of stage IV because of its strong association with peritoneal dissemination. Herein we have described peritoneal lavage cytology using a bedside procedure under local anesthesia.

METHODS

A prospective study of 113 patients with serosa-invading gastric cancer but without peritoneal metastases was performed. A drainage tube was inserted into the abdominal cavity for peritoneal lavage. Patients with negative cytology (CY0) were scheduled for curative gastrectomy.

RESULTS

The bedside procedure was performed safely without any complications. Lavage cytology identified CY1 in 35 (31.0%) patients and CY0 in 78 (69.0%) patients. Patients with CY0 underwent laparotomy and peritoneal lavage cytology, and 9 were found to have peritoneal disease (3 with operative CY1, 4 with peritoneal dissemination, and 2 with both operative CY1 and peritoneal dissemination). Two other patients had small, distant metastases. Finally, curative gastrectomy was achieved in 67 (59.3%) patients, but not in 46 (40.7%) patients. Thus, our bedside, pre-operative peritoneal lavage detected 76.1% (35/46) of noncurative disease before operative with a false-negative rate for detecting peritoneal disease of 20.5% (9/44). Patients with pre-operative CY1 had a poorer prognosis than pre-operative CY0 (2-year cause-specific survival 26.6% vs 82.6%).

CONCLUSION

Pre-operative bedside peritoneal lavage under local anesthesia followed by cytology is a simple and safe method for the pre-operative diagnosis of peritoneal dissemination and may help to reduce unexpected, noncurative surgery.

Advances in imaging diagnosis of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GIST) are the most common non-epithelial tumors. In recent years, the development of imaging technology has resulted in an increase in diagnostic yield of GIST. In this article, we will review the recent advances in imaging diagnosis of GIST.

A systematic review on the clinical diagnosis of gastrointestinal stromal tumors

BACKGROUND

The aim of this work was to assess the prevalence of symptoms of gastrointestinal stromal tumors (GISTs) and the diagnostic yield of clinical procedures for its diagnosis.

METHODS

Medical databases were consulted between 1998 and 2006 for potentially relevant publications. All studies dealing with the clinical presentation of GIST and related diagnostic procedures were included. Two researchers worked independently on the study selection, quality assessment, data extraction, and analysis phases of the study.

RESULTS

Forty-six observational studies were included with a total of 4,534 patients. Gastrointestinal bleeding was the most common clinical presentation. Twenty studies provided adequate information on the diagnostic yield of various procedures. The pooled diagnostic yield of endoscopy + mucosal biopsy and of intestinal contrast radiography was 33.8% (0-100%) and 35.1% (11-100%), respectively, while that of EUS and that of EUS-FNA was 68.7% (40-100%) and 84.0% (73.8-100%), respectively. Abdominal CT scan and MRI had similar pooled diagnostic yields: 73.6% (34.8-100%), and 91.7% (75-100%), respectively.

CONCLUSION

Endoscopy + mucosal biopsy should be reserved to patients with gastrointestinal bleeding. EUS-FNA provides direct visualization of the neoplasm and adequate samples for molecular diagnosis. EUS, abdominal CT and MRI may be considered valid alternatives whenever EUS-FNA is unavailable or a cytological diagnosis is unnecessary.

Contribution of CT to treatment planning in patients with GIST

PURPOSE

The aim of this study was to illustrate the morphological and structural computed tomography (CT) patterns of gastrointestinal stromal tumours (GIST) and to discuss the technique's role in identifying lesions at a higher risk for malignant potential, in treatment planning and in the follow-up of patients with GIST.

MATERIALS AND METHODS

We retrospectively reviewed the CT scans of 26 patients who underwent surgery for histologically confirmed GIST of the stomach (20 cases), the duodenum (1), the caecum (1), the small bowel (2), the descending colon (1) and the rectum (1). CT exams were performed with a single-slice scanner and a 5-mm collimation before and after the intravenous administration of contrast material.

RESULTS

CT allowed us to correctly define the site, size and structure of lesions in all cases and to identify signs of invasion of neighbouring structures in some cases. The lesions exhibited solid density on the unenhanced scan and poor enhancement after contrast-medium administration; lesion structure was homogeneous in ten cases and inhomogeneous in 16; in one case, histology revealed microcalcification that had not been detected by CT.

CONCLUSIONS

CT, with its panoramic capabilities and high contrast resolution, provides essential information for treatment planning and for the follow-up of GIST patients treated with surgery or chemotherapy.

Imatinib mesylate therapy in advanced gastrointestinal stromal tumors: experience from a single institute

Gastrointestinal stromal tumors (GIST) are rare soft tissue sarcomas arising primarily from mesenchymal tissue in the gastrointestinal tract and abdomen. Since there is no effective treatment in the advanced stages, the outcome is poor in such patients. Recently, imatinib mesylate, a selective tyrosine kinase inhibitor, has shown a promising effect in GIST. Hence, we report our experience on the management of advanced GIST with imatinib therapy. A total of 14 patients were enrolled in this study, including 10 males and four females (median age, 51 years). The results showed that the small intestine was the most frequent site of primary lesion, while the liver was the most frequently metastasized organ. Most of the patients experienced tolerable side effects with imatinib therapy, including edema of periorbital area and/or legs and abdominal pain. Only two mortalities were noted during follow-up. The patients clinically benefited from imatinib therapy, with one patient having a complete response, three having a partial response, and seven having stable disease. The results demonstrate promising effects of imatinib in advanced GIST.