Image quality and diagnostic value of portal vein angiography in cirrhotic patients with non-contrast enhanced and contrast enhanced MR angiography

Abstract

Objective To evaluate the imaging quality of the non-contrast enhanced MR angiography of sampling perfection with application optimized contrasts using different flip angle evolutions (SPACE) in showing portal system and compared it with that of the contrast enhanced MR angiography of volumetric interpolated breath-hold examination (VIBE),and study its diagnostic ability in the detection of portosystemic and portohepatic collaterals. Methods Thirty consecutively cirrhotic patients with suspected of portosystemic and portohepatic collaterals were enrolled,and underwent SPACE followed by VIBE at 1.5 T MR scanner.The diagnostic accuracy of SPACE for the portal vein disease was evaluated by two doctors and compared it with that of VIBE.The contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) of two MRA techniques were compared by using the Wilcoxon signed rank test.The quality assessment including scores of the portal vein segments and overall image quality were used the paired t test. Results Twenty-one patients were diagnosed as portal hypertension,including five types of portosystemic collaterals: esophageal varices (n=5),gastric fundic varices (n=11),splenic varices (n=5),paraumbilical varices (n=5) and cavemous transformation (n=2),and one patient was diagnosed as portal vein tumor thrombus.The diagnostic efficiency of SPACE was equivalent to that of VIBE.In SPACE,the SNR were 291±57,301±74,344±76 and the CNR were 231±59,242±73,286±76 at main portal vein,the left branch of portal vein and the right branch of portal vein,respectively.However in VIBE,the SNR were 185±56,176±52,182±52 and the CNR were 57±23,50±21,57±19 at,respectively.Both SNR and CNR of portal vein segments in the former were better than those in the latter (t values were 7.691,7.418,7.946,15.746,13.508 and 13.880,respectively,P 0.05).The scores of displaying the distal branches of left and right portal vein were 2.08±0.78,2.08±0.78 in SPACE,and 1.75±0.53,1.71±0.55 in VIBE,respectively.It was better (Z=-2.138,-2.324,P<0.05) in SPACE than that in VIBE. Conclusion The SPACE has better visualization of portal vein distal branches than VIBE,and it can be applied for the diagnosis of the portal vein disease. Key words: Portal vein; Magnetic resonance imaging; Liver cirrhosis