The radiology of gastrointestinal stromal tumours (GIST)

Abstract

Gastrointestinal stromal tumours (GISTs) comprise a group of smooth muscle mesenchymal alimentary tract tumours of variable malignancy. Recently, the pathophysiology and radiology of these tumours has generated enormous interest following the discovery of a specific, highly effective, chemotherapeutic agent in the form of ST-571 (Imatinib; Glivec, Novartis, Frimley UK). At the time of this review, 106 patients with malignant gastrointestinal stromal tumours seen at the Royal Marsden Hospital have been entered into trials examining the efficacy of varying doses of Imatinib. Burkill et al., also from the Royal Marsden Hospital, have previously reported the distribution, imaging features and pattern of metastatic spread of these tumours (Burkill GJ, Badran M, Al-Muderis O et al. Malignant gastrointestinal stromal tumor: distribution, imaging features, and pattern of metastatic spread. Radiology 2003; 226: 527-32). This new review re-examines the radiological features of GISTs at presentation and well as their changed imaging features following treatment with Imatinib.

Figure 1

Axial enhanced CT showing a large, well-defined soft tissue mass with heterogenous enhancement in a bulky primary small bowel GIST.

Figure 2

Axial CT showing a small, well-defined soft tissue tumour exhibiting homogeneous enhancement arising from the proximal third part of the duodenum.

Figure 3

Low attenuation GIST involving pancreatic head (arrowed) mimicking primary pancreatic adeno-carcinoma. Note lack of dilatation of biliary tree.

Figure 4

Well-marginated low density mass in the position of the distal oesophagus. Biopsy proven GIST.

Figure 5

Axial CT through the mid abdomen demonstrating a large, cavitating fistulating small bowel GIST.

Figure 6

Well-defined exophytic gastric stromal tumour, showing homogeneous enhancement intruding into the body of the stomach (arrow).

Figure 7

(a) Smooth rounded filling defect resulting from sub-mucosal situation of GIST discovered on barium meal. (b) Axial CT showing gastric soft tissue mass with displaced intraluminal oral contrast.

Figure 8

Enhance axial CT demonstrating thin walled ‘cystic’ small bowel GIST.

Figure 9

Punctate foci of calcific density on CT of a thin walled GIST.

Figure 10

Enhanced axial CT demonstrating extensive intrahepatic metastases of low and cystic density.

Figure 11

CT showing very large, well-defined soft tissue tumour arising in the pelvic peritoneum.

Figure 12

Hypervascular GIST shown on superior mesenteric angiogram.

Figure 13

((a), (b)) PET image showing localized increased activity in association with large peritoneal GIST.

Figure 14

((a)–(d)) Imaging impact of Imatinib. Serial axial enhanced CT scans showing initial cystic change in hepatic metastases followed by significant involution of tumour deposits.

Figure 15

Frontal PET image showing residual tumour activity in viable intra-hepatic mass surrounding large inactive area of cystic degeneration.