Computed Tomography Imaging of Gastro Intestinal Stromal Tumour: Retrospective Study of 40 Cases

Abstract

BACKGROUND: GIST is a visceral sarcoma that arises from the gastrointestinal tract. Computed tomography (CT) is an imaging modality of choice for diagnosing GIST. The clinical features and radiologic differential diagnosis of gastrointestinal stromal tumours are discussed by evaluating CT features of GIST in 40 cases. METHODS & MATERIALS: In this study, 40 biopsy proven cases of GIST attending our department from November 2010 to July 2012 are evaluated retrospectively. The CT scan was performed prior to the treatment in all these patients. CT imaging features that were taken into account include tumour location, size/diameter, degree & pattern of enhancement, intraluminal/exophytic, internal necrosis & haemorrhage, perilesional fat stranding, local spread, nodal & distant metastasis. RESULTS: In 26 out of 40 cases (65%), tumour was found in stomach, 8/40 (20%) in small bowel (jejunum & ileum), 4/40 (10%) in omentum and mesentery; and 2 (5%) tumour was found in transverse colon. 28/40 (70%) had exophytic tumour with communication to lumen of gastrointestinal tract or in omentum and mesentery; rest 12/40 (30%) had polypoidal mass. Size of tumour ranged from 4 to 15 cm, with mean of 7.9 cm. 30/40 (75%) cases showed heterogeneous enhancement with necrosis and/or calcification, rest 10/40 (25%) had homogenous enhancement. The CT HU ranged from 35 to 55, with mean of 40. 28/40 (75 %) cases had well defined margins of tumour, and rest 12 (30%) cases showed perilesional fat stranding and loss of fat plane with adjacent organ. 4/40 (10%) cases showed regional nodal involvement and 6/40 (15%) cases shows distant metastasis to liver & lungs. CONCLUSIONS: The stomach was the commonest site of GIST occurrence among our patients. The CT features of GIST were exophytic, ulcerated mass with well-defined tumour margins, and heterogeneous enhancement on post-contrast CT images.