Magnetic resonance imaging (MRI) plays an important role in abdominal imaging. The high contrast resolution offered by MRI provides better lesion detection and its capacity to provide multiparametric images facilitates lesion characterization more effectively than computed tomography. However, the relatively long acquisition time of MRI often detrimentally affects the image quality and limits its accessibility. Recent developments have addressed these drawbacks. Specifically, multiphasic acquisition of contrast-enhanced MRI, free-breathing dynamic MRI using compressed sensing technique, simultaneous multi-slice acquisition for diffusion-weighted imaging, and breath-hold three-dimensional magnetic resonance cholangiopancreatography are recent notable advances in this field. This review explores the aforementioned state-of-the-art techniques by focusing on their clinical applications and potential benefits, as well as their likely future direction.
Cholangiopancreatography, Magnetic Resonance ; Hand Strength ; Magnetic Resonance Imaging

OBJECTIVE: To compare the breathing effects on dynamic contrast-enhanced (DCE)-MRI between controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA)-volumetric interpolated breath-hold examination (VIBE), radial VIBE with k-space-weighted image contrast view-sharing (radial-VIBE), and conventional VIBE (c-VIBE) sequences using a dedicated phantom experiment. MATERIALS AND METHODS: We developed a moving platform to simulate breathing motion. We conducted dynamic scanning on a 3T machine (MAGNETOM Skyra, Siemens Healthcare) using CAIPIRINHA-VIBE, radial-VIBE, and c-VIBE for six minutes per sequence. We acquired MRI images of the phantom in both static and moving modes, and we also obtained motion-corrected images for the motion mode. We compared the signal stability and signal-to-noise ratio (SNR) of each sequence according to motion state and used the coefficients of variation (CoV) to determine the degree of signal stability. RESULTS: With motion, CAIPIRINHA-VIBE showed the best image quality, and the motion correction aligned the images very well. The CoV (%) of CAIPIRINHA-VIBE in the moving mode (18.65) decreased significantly after the motion correction (2.56) (p < 0.001). In contrast, c-VIBE showed severe breathing motion artifacts that did not improve after motion correction. For radial-VIBE, the position of the phantom in the images did not change during motion, but streak artifacts significantly degraded image quality, also after motion correction. In addition, SNR increased in both CAIPIRINHA-VIBE (from 3.37 to 9.41, p < 0.001) and radial-VIBE (from 4.3 to 4.96, p < 0.001) after motion correction. CONCLUSION: CAIPIRINHA-VIBE performed best for free-breathing DCE-MRI after motion correction, with excellent image quality.
Acceleration ; Artifacts ; Magnetic Resonance Imaging ; Respiration* ; Signal-To-Noise Ratio

Objective To evaluate the value of 3T magnetic resonance imaging (MRI) in the preoperative T staging of potentially resectable esophageal cancer(EC), compared with endoscopic ultrasonography (EUS). Methods Patients with resectable EC pathologically confirmed by biopsy from March 2015 to September 2016 were prospectively enrolled. All patients underwent MRI (including T2-TSE-BLADE,DWI and radial-VIBE)and EUS one week after the biopsy,and MRI were performed prior to EUS, both MRI and EUS were acquired within one week before surgery. Two readers with more than 5 years experiences in the MRI diagnosis evaluated the MR image quality using a 5-point score independently. T staging was assigned on MRI and EUS by the two MRI readers using double-blind method and one endoscopist in accordance with the 7th edition of AJCC TNM Classification for EC, and any disagreement between two MRI readers was resolved by consensus with discussion to the third senior MRI doctor. The inter-observer agreement between two MRI readers were calculated using Kappa test for image quality scores and T staging results. Considering postoperative pathological T staging results as the gold standard, the performances of MRI and EUS were evaluated based on the accuracy rate and analyzed by χ2 test. Results A total of 70 patients were enrolled in the study, the good image quality cases (≥ 3 scores) were 66 in reader 1 and 68 in reader 2. The inter-observer agreement of the image quality scores by two readers was excellent (Kappa=0.824, P<0.05). The pathological results revealed 16 cases of T1 stage, 18 cases of T2 stage, 30 cases of T3 stage, and 6 cases of T4a stage. The inter-observer agreement of the preoperative T staging of EC by two readers was excellent (Kappa=0.809, P<0.05). The accuracy rates of MRI and EUS for preoperative T staging of EC were 92.9% (65/70) and 67.1% (47/70), respectively, and the difference in accuracy rates of two techniques was statistically significant (χ2=14.5, P<0.05). Conclusions The accuracy rate of MRI for preoperative T staging of EC is significantly higher than that of EUS. MRI can be used as a noninvasive method for preoperative T staging of EC.