MR measurements of mesenteric venous flow: prospective evaluation in healthy volunteers and patients with suspected chronic mesenteric ischemia

Chronic mesenteric ischemia. Clinical presentation and diagnosis

Owing to a heightened awareness of the disease as well as improved diagnostic tests, chronic mesenteric ischemia is now recognized as a more common cause of abdominal pain. The classic symptoms of postprandial abdominal pain with weight loss are evident in the majority of proven cases; most patients also have other evidence of advanced atherosclerotic vascular disease. Several new diagnostic techniques are being developed and tested, most notably color duplex imaging, although angiography still remains the diagnostic gold standard. It is hoped that better noninvasive testing may eventually eliminate the need for angiography, as well as lead to a more expedient diagnosis of chronic mesenteric ischemia.

MR angiography of abdominal ischemia

Advances during the past decade in MRI have made this modality increasingly suitable for evaluating abdominal vascular diseases. Preliminary results in canine models and humans suggest that MRI has the potential of becoming a definitive, noninvasive test for the diagnosis of both acute and chronic mesenteric ischemia. MRI can provide both morphological information about the patency or degree of stenosis in mesenteric vessels as well as quantitative functional information such as blood flow and blood oxygen saturation in these vessels. The MR techniques developed for studying the mesenteric circulation also can be used for improving the diagnosis and posttreatment evaluation of vascular diseases in other abdominal organ systems.

Magnetic resonance imaging detection of extraluminal enterally administered gadopentetate dimeglumine in a rat model of intestinal ischemia

RATIONALE AND OBJECTIVES

We assessed whether intestinal ischemia would result in transudation of orally administered gadopentetate dimeglumine into the peritoneal cavity.

METHODS

Twenty-eight rats were anesthetized and midline laparotomy was performed. Animals were divided into four groups: control, ligation of a single mesenteric arcade, ligation of six consecutive arcades, and ligation of the anterior mesenteric artery (analogous to the superior mesenteric artery in humans). A 1.0-ml enteric bolus of gadopentetate dimeglumine diluted with sterile water (1:1) was given via gavage. Magnetic resonance imaging was performed 2 hr after laparotomy and reviewed for the presence of intraperitoneal gadopentetate dimeglumine by two experienced observers. Animals were sacrificed 24 hr after surgery for pathologic examination.

RESULTS

Four animals died prior to sacrifice. The bladder had a grossly high signal in all cases, implying some degree of intravascular absorption of the contrast material. A correlation was found between increasing mean radiology scores and increasing numbers of ligated vessels. The intraperitoneal signal tended to be higher in experimental animals than in control animals. Histologic damage was more severe in experimental animals (ischemic changes extending deeper into the intestinal wall) than in control animals.

CONCLUSION

Direct visualization of spilled gastrointestinal gadopentetate dimeglumine helped discriminate ischemic from control rats in this model.

Systolically gated 3D phase contrast MRA of mesenteric arteries in suspected mesenteric ischemia

OBJECTIVE

Our goal was to assess the value of MRA for detecting stenoses in the celiac (CA) and superior mesenteric (SMA) arteries in patients suspected of having chronic mesenteric ischemia, using an optimized systolically gated 3D phase contrast technique.

MATERIALS AND METHODS

In an initial study in 24 patients who underwent conventional angiography of the abdominal vessels for different clinical indications, a 3D phase contrast MRA technique (3D-PCA) was evaluated and optimized to image the CAs and SMAs. Subsequently, a prospective study was performed to assess the value of systolically gated 3D-PCA in evaluation of the mesenteric arteries in 10 patients with signs and symptoms of chronic mesenteric ischemia. Intraarterial digital subtraction angiography and surgical findings were used as the reference standard.

RESULTS

In the initial study, systolic gating appeared to be essential in imaging the SMA on 3D-PCA. In 10 patients suspected of mesenteric ischemia, systolically gated 3D-PCA identified significant proximal disease in the two mesenteric vessels in 4 patients. These patients underwent sucessful reconstruction of their stenotic vessels.

CONCLUSION

Cardiac-gated MRA may become a useful tool in selection of patients suspected of having mesenteric ischemia who may benefit from surgery.