MR versus multislice CT cholangiography in evaluating patients with obstruction of the biliary tract

BACKGROUND

We compared magnetic resonance cholangiography (MRC) with multislice computed tomographic (MSCT) cholangiography in the assessment of patients with bile duct obstruction.

METHODS

Thirty-six patients with clinical or biochemical signs of biliary obstruction were prospectively studied. MRC was performed with fast spin-echo and single-shot fast spin-echo sequences. Source images, maximum intensity projection, and multiplanar reconstruction were evaluated. MSCT cholangiography was performed without biliary contrast agent, with intravenous injection of 150 mL of iodinated contrast material at 4 mL/s, 2.5-mm slice thickness, 7.5-mm/s table speed, and 1.25-mm reconstruction interval. Axial, multiplanar, and minimum intensity projection reformatted images were evaluated. MRC and MSCT findings were compared with endoscopic retrograde cholangiopancreatography (ERCP; 20 patients), percutaneous cholangiography (eight patients), intraoperative cholangiography (two patients), surgery (11 patients), and cytology (11 patients) with respect to cause and site of obstruction.

RESULTS

With regard to presence and site of obstruction, agreement was observed across MRC, MSCT cholangiography, and reference investigations in all cases. Concerning cause, the correct diagnosis was made by MSCT cholangiography in 34 of 36 patients. Two cases of common bile duct lithiasis, diagnosed on MRC and ERCP, were missed by MSCT cholangiography.

CONCLUSION

MSCT cholangiography can be considered a possible noninvasive alternative to MRC.

Value of an early arteriographic acquisition for evaluating the splanchnic vessels as an adjunct to biphasic CT using a multislice scanner

Our objective was to assess the clinical value of an early arterial scan for assessing the hepatic and mesenteric vasculature in patients with suspected primary or metastatic hypervascular liver disease undergoing multislice computed tomography. In 42 patients a very early arteriographic scan was performed before standard arterial and portal venous scans. Technical parameters of the very early acquisition were: 2.5-mm image thickness; table speed 15 mm/s; pitch 6; 120 kVp; 300 mA; 8.9-s scan time; cranio-caudal acquisition direction; 1.25-mm image interval reconstruction;16-s delay after injection of 110 ml of iodinated contrast agent at 5 ml/s; scan volume focused to image hepatic, splenic, and superior mesenteric arteries (SMA). Standard arterial and portal venous phases were performed with 5-mm image thickness, 15-mm/s table speed, pitch 6, 8- to 10-s scan time, 30- and 70-s delay. The three phases were performed during three different breath-holds. Axial, multiplanar reformatted, maximum intensity projection, and volume-rendering images were evaluated. Image quality was scored, and vascular abnormalities were recorded. Digital subtraction angiography (DSA) was performed in 17 patients. In 36 of 42 patients good-quality CT angiograms were obtained. In 9 patients 12 vascular abnormalities were found, all confirmed at DSA: 3 right hepatic arteries originating from the SMA, 2 left hepatic arteries from the gastric artery, 2 stenoses of the SMA, 1 independent origin of the hepatic and splenic arteries, 2 arteriovenous fistulas, and 2 aneurysms of the common hepatic artery and the SMA. This technique could add important information about vascular splanchnic anatomy which would be particularly useful for surgeons and interventional radiologists.

[Magnetic resonance imaging of the small intestine and colon in Crohn's disease]

Three normal volunteers and 20 patients with known Crohn's disease were examined with MRI--at 0.5 Tesla and with a superconductive magnet. Coronal T1-weighted GE images were mainly acquired, before and after i.v. Gd-DTPA injection in breath hold (TR 70 ms, TE 13 ms, FA 70 degrees). MR findings were compared with the results of small and large bowel enema. In 6 patients (30%) the abnormal loops were missed. In the other 14 patients (70%) MRI did depict the affected loops in the same sites as depicted by conventional radiography. The bowel wall was thickened (4-10 mm) in all patients. In 10 patients the thickened wall was markedly enhanced after Gd-DTPA injection. In 6 patients MRI demonstrated disease complications--i.e., stenoses, fistulae and abscesses--missed by conventional radiography. In 7 patients MRI showed the bowel to be more involved than demonstrated by conventional studies. Bowel wall thickening appeared to be a constant and reliable sign of disease. Wall enhancement was a less frequent sign but, when present, it was considered as characteristic as wall thickening. In the staging of Crohn's disease, MRI yields more pieces of information than conventional radiography and depicts the involvement of the intestinal wall and of its surrounding spaces.