eMedicine Specialties > Radiology > Gastrointestinal

Gastrointestinal Stromal Tumors - Leiomyoma/Leiomyosarcoma: Imaging

Author: Vu H Nguyen, MD, Staff Physician, Department of Radiology, University of Wisconsin Hospitals and Clinics
Coauthor(s): Andrew Taylor, MD, Professor, Department of Radiology, University of Wisconsin Hospitals and Clinics
Contributor Information and Disclosures

Updated: Aug 5, 2008

Radiography

Findings

Plain radiographs usually offer little in the evaluation of gastrointestinal stromal tumors (GISTs). In the chest, esophageal GISTs may appear as a soft tissue mass in the lower two thirds of the mediastinum. In the abdomen, the soft tissue mass may cause deformation of the gastric air shadow, or it may displace loops of bowel. Abdominal films may depict an obstructive bowel pattern. If they are necrotic lesions, collections of air may be visualized within the tumor.20

Regardless of the location of GISTs, barium-enhanced images demonstrate predominantly intramural masses with potential exophytic components. The tumor margins usually are smooth, but with ulceration, some surface irregularity is present. As with other intramural masses, the tumor borders form right or obtuse angles with the adjacent visceral wall. En face, the intraluminal surfaces often have well-defined margins (see Images 7-10).

Because the tumors are intramural but extramucosal, the overlying mucosa may be intact. With tumors of the stomach, areae gastricae is preserved over the tumor mass. However, overlying mucosal ulcerations are often present; they are more common in malignant GISTs. These ulcerations fill with barium, causing a bull's-eye or target-lesion appearance (see Image 11).

If necrosis and cavitation are present, barium may fill the inner parts of the tumor mass (see Images 12-13).4,5,18,20,21 At times, the mass is entirely exophytic and, thus, is not appreciated during contrast-enhanced examination. Barium images outline the intraluminal portion of this tumor; frequently, a substantial exophytic extension is present (see Images 14-15).

Degree of Confidence

One group reported that double-contrast images show abnormalities in 80% of cases of gastrointestinal stromal tumors (GISTs).4

Computed Tomography

Findings

CT for gastrointestinal stromal tumors (GISTs) should be performed with both oral and intravenous contrast materials. CT is ideal in defining the endoluminal and exophytic extent of tumor. Smaller gastrointestinal stromal tumors appear as smooth, sharply defined intramural masses with homogeneous attenuation (see Image 9).

With contrast enhancement, the tumor may appear to have a rim, or it may be uniform in appearance (see Image 15). Occasionally, dense focal calcifications are present. Larger GISTs with necrosis appear as heterogeneous masses with enhancing borders of variable thickness and irregular central areas of fluid, air, or oral contrast attenuation that reflect necrosis (see Image 4, Image 13). Overlying mucosal ulcerations may be present, and the tumor may extend into nearby structures.

CT is sensitive for the detection of metastatic liver, peritoneal, lung, and bone lesions. The diagnosis of GIST may be suggested by the presence of a large, complex, intestinal mass with liver lesions but without significant lymphadenopathy. Liver lesions can be hypervascular, or they may appear as cystic multilocular lesions with fluid-fluid levels (see Image 21).2,5,8,18,20,22

Degree of Confidence

CT scanning has good sensitivity for the detection of GISTs; abnormalities may be seen in 87% of cases.4

Magnetic Resonance Imaging

Findings

Among imaging studies, MRI has the best tissue contrast, which aids in the identification of masses within the GI tract. Furthermore, the ability to image in multiple planes facilitates localization and diagnosis. Intravenously administered contrast material is needed to evaluate lesion vascularity.

Gastrointestinal stromal tumors (GISTs) appear as sharply delineated, heterogeneous masses with cystic and necrotic areas. The masses tend to be isointense relative to skeletal muscle on T1-weighted images and hyperintense on T2-weighted images. Signal-intensity voids are present if gas is present within areas of necrotic tumor.18,20,23

Ultrasonography

Findings

Ultrasonography is ideal for guided-needle biopsy of known lesions, if such a procedure is indicated. With immunohistochemical staining methods, the diagnosis may be made before surgery.24 However, aspiration (eg, fine-needle aspiration) and biopsy should be used selectively because of the risk of tumor seeding or peritoneal spillage.4,25 Both are associated with a worse prognosis.

On sonograms, larger gastrointestinal stromal tumors (GISTs) appear as complex masses with cystic and solid components, which are consistent with their tendency to undergo necrosis.20,23

Endoscopic ultrasonography may be valuable in the evaluation of GISTs. The tumors appear as hypoechoic masses that are contiguous with the fourth hypoechoic layer of the GI wall, which corresponds to the muscularis propria. Characteristics associated with malignancy include tumor size greater than 4 cm, an irregular extraluminal border, echogenic foci, and the presence of cystic spaces.4

Degree of Confidence

Ultrasonography is only moderately sensitive for the detection and evaluation of gastrointestinal stromal tumors. Bowel gas and acoustic shadowing obscure portions of the bowel and mesentery.

Angiography

Findings

On angiography, gastrointestinal stromal tumors (GISTs) appear as relatively well-circumscribed, hypervascular lesions with central avascularity. They have large feeding arteries and draining veins, and they show intense tumor staining (see Images 16-20).8

More on Gastrointestinal Stromal Tumors - Leiomyoma/Leiomyosarcoma

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Imaging: Gastrointestinal Stromal Tumors - Leiomyoma/Leiomyosarcoma
Follow-up: Gastrointestinal Stromal Tumors - Leiomyoma/Leiomyosarcoma
Multimedia: Gastrointestinal Stromal Tumors - Leiomyoma/Leiomyosarcoma
References
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References

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Further Reading

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Keywords

gastrointestinal stromal tumors, gastrointestinal neoplasms, GIST, GI stromal tumors, GI tumors, gastrointestinal tumors, leiomyoma, leiomyosarcoma, gastrointestinal sarcoma, gastrointestinal mesenchymal tumor, GISTs, leiomyoblastoma, schwannoma, CD34, CD117, c-kit, benign tumors, stomach cancer

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Contributor Information and Disclosures

Author

Vu H Nguyen, MD, Staff Physician, Department of Radiology, University of Wisconsin Hospitals and Clinics
Vu H Nguyen, MD is a member of the following medical societies: American College of Radiology and Radiological Society of North America
Disclosure: Nothing to disclose.

Coauthor(s)

Andrew Taylor, MD, Professor, Department of Radiology, University of Wisconsin Hospitals and Clinics
Andrew Taylor, MD is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, Association of University Radiologists, and Radiological Society of North America
Disclosure: Nothing to disclose.

Pharmacy Editor

Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.

Managing Editor

Udo P Schmiedl, MD, PhD, Clinical Professor, Department of Radiology, University of Washington; Consulting Staff, Swedish Medical Center, University of Washington Medical Center, Seattle Radiologists
Udo P Schmiedl, MD, PhD is a member of the following medical societies: American College of Radiology and Radiological Society of North America
Disclosure: Nothing to disclose.

CME Editor

Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.

Chief Editor

Eugene C Lin, MD, Clinical Assistant Professor of Radiology, University of Washington Medical School
Eugene C Lin, MD is a member of the following medical societies: American College of Nuclear Medicine, American College of Radiology, Radiological Society of North America, and Society of Nuclear Medicine
Disclosure: Nothing to disclose.

 
 
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