Prospective Study
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World J Gastroenterol. Sep 21, 2014; 20(35): 12621-12627
Published online Sep 21, 2014. doi: 10.3748/wjg.v20.i35.12621
Optimal b value of diffusion-weighted imaging on a 3.0T magnetic resonance scanner in Crohn’s disease
Qi Feng, Yun-Qi Yan, Jiong Zhu, Jin-Lu Tong, Jian-Rong Xu
Qi Feng, Yun-Qi Yan, Jiong Zhu, Jian-Rong Xu, Department of Radiology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
Jin-Lu Tong, Department of Gastroenterology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
Author contributions: Each author had participated sufficiently to take public responsibility for its content; Feng Q and Xu JR were guarantors of integrity of the entire study, and contributed to the study concepts and design; Feng Q and Zhu J contributed to the literature research; Tong JL contributed to the clinical studies; Feng Q and Yan YQ contributed to the experimental studies/data analysis; Feng Q prepared the manuscript; Xu JR contributed to the manuscript editing.
Supported by National Basic Research Program of China, No. 2012CB932600; and Shanghai Leading Academic Discipline Project, No. S30203
Correspondence to: Jian-Rong Xu, Director, Department of Radiology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, No. 1630, Dongfang Road, Pudong New District, Shanghai 200127, China. renjixujianrong@126.com
Telephone: +86-21-68383259 Fax: +86-21-50896639
Received: December 25, 2013
Revised: March 18, 2014
Accepted: June 14, 2014
Published online: September 21, 2014
Abstract

AIM: To determine the optimal b value of diffusion-weighted imaging for detecting active inflammation in Crohn’s disease.

METHODS: Thirty-one patients clinically diagnosed with active Crohn’s disease were referred for magnetic resonance examination. All patients were scanned on a 3.0T magnetic resonance scanner using the same protocol involving four different b values (800, 1500, 2000 and 2500 s/mm2). The diagnostic effect of diffusion-weighted imaging was evaluated and compared with endoscopic findings. The diffusion-weighted image quality of four b value groups was evaluated and apparent diffusion coefficient was measured for both normal and inflammatory intestinal segments.

RESULTS: The contrast-to-noise ratio and signal-to-noise ratio were not satisfied when b value 2000 or 2500 s/mm2 was adopted (36.52 ± 14.95 vs 34.78 ± 24.83, P > 0.05; 53.58 ± 23.45 vs 47.58 ± 29.67, P > 0.05). The qualitative image quality was not enough to meet diagnostic requirement. No matter which b value was chosen, the apparent diffusion coefficient of inflammatory intestinal segments was significantly lower than that of normal intestinal segments (1.38 ± 0.28 vs 2.00 ± 0.38, P < 0.01; 1.09 ± 0.20 vs 1.50 ± 0.28, P < 0.01; 0.95 ± 0.19 vs 1.34 ± 0.28, P < 0.01; 0.88 ± 0.14 vs 1.20 ± 0.21, P < 0.01). The lesion detection rate (90.32%), diagnostic sensitivity (81.18%) and specificity (95.10%) would be appropriate when b value 1500 s/mm2 was adopted.

CONCLUSION: High b value is suitable for intestinal DW examination on a high field MR scanner.

Keywords: Crohn’s disease, Diffusion-weighted imaging, b value, Magnetic resonance image, 3.0 Tesla

Core tip: To date, nearly all the articles regarding diffusion-weighted imaging (DWI) utility in active Crohn’s disease chose relatively lower b values, and the examinations were finished on 1.5T magnetic resonance (MR) scanners. In our study, we try to investigate the appropriate b value of DWI on a high field MR scanner. During scanning, we adopted a low b value (800 s/mm2), a high b value (1500 s/mm2) and two very high b values (2000 and 2500 s/mm2). Our findings suggested that the b value of 1500 s/mm2 would be appropriate and when DWI was adopted on a 3.0T MR scanner, a high b value should be applied.