Authors:
R. Ochiai, H. Sugimura, T. Kodama, T. Jinnouchi, E. Furukouji, T. Sakae, S. Tamura; Kiyotake/JP
DOI:
10.1594/ecr2009/C-833
Methods and Materials
Materials:
Between November 2007 and July 2008, 31 consecutive patients who underwent MR portography at the University of Miyazaki Hospital were enrolled in this study. These included 20 men and 11 women patients, (mean age of 63.4 years; range, 21-80 years). The patient population is presented in Table 1.
Methods:
Magnetic resonance imaging (MRI) examination was performed using a 1.5-T system (EXCELART Vantage; TOSHIBA) with a body phased-array coil. SPIO- enhanced MR portography was performed using coronal respiratory-triggerd 3D true SSFP with the following parameters: TR, 5 ms; TE, 2.5 ms; flip angle, 120°; black-blood inversion time (BBTI) , 1,300 ms; spin labeling pulse thickness, 200 mm; slice thickness, 3.5 mm; matrix, 256×256; field of view, 380 mm; and speed-up factor, 2. Vessel depiction by the spin labeling technique was influenced mainly by the location of the pulse and BBTI. The location of the pulse controls the vessel of interest. BBTI is the inversion time from the spin labeling pulse to the spin excitation pulse. The contrast of the image can be altered by changing the BBTI. The spin labeling pulse was placed to mark both the splenic vein and the superior mesenteric vein that flow directly into the portal vein (Fig. 1). Ferucarbotran (Resovist; dose, 0.016 ml/kg) was manually and rapidly injected as an intravenous bolus and 20 ml saline was flushed. This sequence was performed before and after contrast agent injection.
Analysis:
The contrast-to-noise ratios (CNRs) of the portal vein were measured as follows (Table 2). The statistical significance of the difference in the CNRs was evaluated using a paired t test. A difference was considered statistically significant if the P-value was less than 0.05.
Three radiologists assessed the image quality of the maximum intensity projection (MIP) MR portography by using the following grading system: 5, excellent; 4, good; 3, fair; 2, poor; and 1, very poor. The mean score given by the 3 radiologists was defined as the qualitative imaging score for the portal vein. The statistical significance of the difference in the qualitative imaging score was evaluated using the Wilcoxon signed-rank test. A difference was considered statistically significant if the P-value was less than 0.05.