Background:In liver diffusion-weighted imaging (DWI), single-shot echo-planar imaging (SS-EPI) sequences are susceptible to motion artifacts, resulting in image blurring and decreased lesion detection rates. This study aimed to develop and optimize a motion-corrected (MOCO) technique for liver DWI at 3 Tesla (3T). The technique incorporates motion correction, complex averaging, and a combination of a reparametrized sinc fatsat pulse with an optimized water excitation pulse. Methods:This prospective cross-sectional study performed at Fujian Medical University Union Hospital included 42 healthy volunteers who underwent four SS-EPI DWI sequences on a 3T magnetic resonance imaging (MRI) system between January 2023 and March 2023. The sequences included a navigator-triggered (NT) MOCO-DWI, two free-breathing (FB) MOCO-DWI, and an FB conventional DWI (FB cDWI) sequence. Motion correction and complex averaging were performed for both MOCO-DWI sequences, and fat suppression was achieved using either a sinc fatsat pulse with optimized water excitation or a conventional spectral attenuated inversion recovery (SPAIR) pulse. Liver signal-to-noise ratio (SNR) was measured at b=1,000 s/mm2. Qualitative parameters were independently evaluated by three radiologists using 5-point Likert scales. Quantitative parameters were assessed using the Kolmogorov-Smirnov test, and variance homogeneity was assessed using Levene's test. Regarding the qualitative analysis, the Friedman test was used to compare subjective scores among the four techniques. Results:The SNRs of the liver were significantly higher with FB MOCO-DWI compared to the other EPI DWI sequences at b=1,000 s/mm2 (P<0.05). In the superior-inferior direction, the SNRs of the inferior level of the liver were higher than those of the superior level in NT MOCO-DWI. The qualitative results showed significantly higher ratings for NT MOCO-DWI and FB MOCO-DWI compared to the other EPI DWI sequences at b=1,000 s/mm2 (P<0.05). Regarding the apparent diffusion coefficient (ADC) quantification, the ADC values of the left lobe were higher than those of the right lobe in all four techniques. Conclusions:The proposed EPI DWI technique, incorporating motion correction, complex averaging, and a modified fat suppression scheme using spectral fat saturation and binomial water excitation, was found to be clinically feasible for liver MRI. The FB MOCO-DWI sequence, with its superior SNR and excellent image quality, is recommended for liver DW imaging at 3T in clinical routine.

RATIONALE AND OBJECTIVES:The purpose of the present study was to evaluate the clinical feasibility of the modified 3D breath-hold magnetic resonance cholangiopancreatography with parallel imaging (3D-BH-PI-MRCP) using a spatially selective radiofrequency excitation pulse in patients with suspected pancreaticobiliary diseases. Moreover, we also compared its image quality with those of the original 3D-BH-PI-MRCP with a nonselective exciting pulse and the 3D breath hold compressed sensing magnetic resonance cholangiopancreatography (3D-BH-CS-MRCP).MATERIALS AND METHODS:Between January 2021 and July 2021, 106 patients prospectively underwent modified 3D-BH-PI-MRCP, original 3D-BH-PI-MRCP and 3D-BH-CS-MRCP at 3T in this study. The Friedman test was performed to compare the contrast, signal-to-noise-ratio (SNR), and contrast-noise-ratio, overall image quality, and duct visualization among the three protocols.RESULTS:The contrast ratio, SNR and contrast-to-noise ratio of the common bile duct differed significantly among the three sequences (p < 0.001). Compared to the 3D-BH-CS-MRCP protocol, the overall imaging quality of the two 3D-BH-PI-MRCP was higher but not significantly different. The scores for the anterior and posterior branches visualization were significantly higher in the original 3D-BH-PI-MRCP compared to the 3D-BH-CS-MRCP, but were no significant differences between the modified 3D-BH-PI-MRCP and the 3D-BH-CS-MRCP.CONCLUSION:The modified 3D-BH-PI-MRCP with a spatially selective radiofrequency excitation pulse could provide comparable image quality to the original 3D-BH-PI-MRCP and the 3D-BH-CS-MRCP during a single breath hold (22 seconds), and showed improved SNR and superior visualization of the pancreaticobiliary tree.

Background Simultaneous multislice diffusion-weighted imaging (SMS-DWI) has been used to reduce image acquisition time. The purpose of this study was to investigate the feasibility of diffusion kurtosis imaging (DKI) based on the SMS technique in the liver and the influence of this method compared with that of conventional DWI sequences on image quality and DKI-derived quantitative parameters. Methods Forty volunteers underwent SMS-DWI sequences with acceleration factors of 2 and 3 (SMS2-DWI, SMS3-DWI) and conventional DWI (C-DWI) of the liver with three b-values (50, 800, 2000 s/mm 2 ) in a 3T system. Qualitative image quality parameters and quantitative measurements of the signal-to-noise ratio (SNR), mean kurtosis (MK), mean apparent diffusivity (MD) and apparent diffusion coefficient (ADC) for the liver were compared between the three sequences. Results The scan times of C-DWI, SMS2-DWI, and SMS3-DWI were 4 min 11 s, 2 min 2 s, and 1 min 34 s, respectively. For all image quality parameters, there were no significant differences observed between C-DWI and SMS2-DWI (all p > 0.05) in the images with b-values of 800 and 2000 s/mm 2 . C-DWI and SMS2-DWI exhibited better scores than SMS3-DWI (all p < 0.01) in the images with b-values of 2000 s/mm 2 . In the images with b-values of 800 s/mm 2 , C-DWI and SMS2-DWI exhibited better scores than SMS3-DWI for artefacts and overall image quality (all p < 0.01), and C-DWI exhibited better scores than SMS3-DWI for the visibility of intrahepatic vessels ( p < 0.001). There were no significant differences in the sharpness of the right lobe edge ( p = 0.144), conspicuity of the left lobe ( p = 0.370) or visibility of intrahepatic vessels ( p = 0.109) between SMS2-DWI and SMS3-DWI. There were no significant differences in the sharpness of the right lobe edge ( p = 0.066) or conspicuity of the left lobe ( p = 0.131) between C-DWI and SMS3-DWI. For the b-value of 800 s/mm 2 , there were no statistically significant differences between SMS2-DWI and C-DWI ( p = 1.000) or between SMS2-DWI and SMS3-DWI ( p = 0.059), whereas SMS3-DWI had a significantly lower SNR than C-DWI ( p = 0.024). For the DKI-derived parameters (MK and MD) and ADC values, there were no significant differences between the three sequences (MK, p = 0.606; MD, p = 0.831; ADC, p = 0.264). Conclusions SMS-DWI with an acceleration factor of 2 is feasible for the liver, resulting in considerable reductions in scan time while maintaining similar image quality, comparable DKI parameters and ADC values compared with those of C-DWI.

Purpose: To evaluate the image quality and image consistency between 3D Breath-hold (BH)-MRCP with parallel imaging (3D-BH-PI-MRCP) and 3D-BH compressed sensing (CS)-MRCP (3D-BH-CS-MRCP) in patients with suspected pancreaticobiliary diseases, compared with 3D navigator-triggered (NT)-MRCP. Materials and methods: The A total number of 109 patients who underwent 3D-NT-MRCP, 3D-BH-PI-MRCP and 3D-BH-CS-MRCP were prospectively enrolled in this study. The Friedman test was performed to compare quantitative values, image acquisition time, the presence of artifacts, overall image quality, and duct visualization among the three protocols. Additionally, we compared 3D-BH-PI-MRCP and 3D-BH-CS-MRCP with 3D-NTMRCP in morphological consistency of main pancreatic duct and common bile duct (CBD) based on overall image quality score of = 4. Results: Three MRCP methods were successfully performed in all the patients. The contrast ratio, SNR and CNR of the CBD were significantly higher for 3D-BH-CS-MRCP than those for 3D-NT-MRCP and 3D-BH-PI-MRCP images. Overall image quality did differ significantly across the three sequences. Visualization of the CBD, RHD, LHD, anterior branch, posterior branch and cystic duct was similar with the 3D-BH-CS-MRCP and 3D-BH-PI-MRCP sequences. In contrast, segment 2 or 3 branch and main pancreatic duct visualization were significantly better with 3D-BH-PI-MRCP than with 3D-BH-CS-MRCP and 3D-NT-MRCP (p < 0.001). Conclusions: Both the two breath-hold approaches were considering the time-saving advantages without deterioration of image quality. Compared with 3D-BH-CS-MRCP, 3D-BH-PI-MRCP yielded significantly better visualization of the segment 2 and 3 branch of the intrahepatic duct and performed better consistency in main pancreatic duct and common bile duct morphology.

Objective To investigate the feasibility of quantitative intravoxel incoherent motion (IVIM) and diffusion kurtosis imaging (DKI) analyses in the upper abdominal organs by simultaneous multislice diffusion-weighted imaging (SMS-DWI). Subjects and Methods In this prospective study, a total of 32 participants underwent conventional DWI (C-DWI) and SMS-DWI sequences with acceleration factors of 2 and 3 (SMS2-DWI and SMS3-DWI, respectively) in the upper abdomen with multiple b-values (0, 10, 20, 50, 80, 100, 150, 200, 500, 800, 1000, 1500, and 2000 seconds/mm2) on a 3 T system (MAGNETOM Prisma; Siemens Healthcare, Erlangen, Germany). Image quality and quantitatively measurements of apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudodiffusion coefficient (D*), perfusion fraction (f), mean kurtosis (MK), and mean apparent diffusivity (MD) for the liver, pancreas, kidney cortex and medulla, spleen, and erector spine muscle were compared between the 3 sequences. Results The acquisition times for C-DWI, SMS2-DWI, and SMS3-DWI were 10 minutes 57 seconds, 5 minutes 9 seconds, and 3 minutes 54 seconds. For image quality parameters, C-DWI and SMS2-DWI yielded better results than SMS3-DWI (P < 0.05). SMS2-DWI had equivalent IVIM and DKI parameters compared with that of C-DWI (P > 0.05). No statistically significant differences in the ADC, D, f, and MD values between the 3 sequences (P > 0.05) were observed. The D* and MK values of the liver (P = 0.005 and P = 0.012) and pancreas (P = 0.019) between SMS3-DWI and C-DWI were significantly different. Conclusions SMS2-DWI can substantially reduce the scan time while maintaining equivalent IVIM and DKI parameters in the abdominal organs compared with C-DWI.

Objective:To explore the technical advantages of MR cholangiopancreatography (MRCP) with single breath holding high parallel acquisition factor 3-D variable flip angle fast spin echo (3D-SPACE) sequence.Methods:From November 2018 to March 2019, 75 patients who underwent MRCP examination in our hospital were prospectively enrolled, with single breath holding high parallel acquisition factor 3D-SPACE sequence and free breathing navigation gated 3D-SPACE sequence. Three experienced radiologists scored the overall image quality, artifacts, CBD visibility, left and right hepatic ducts, right anterior and posterior branches, second and third branches, main pancreatic duct and gallbladder duct with four scales. Paired t test was used for statistical analysis. Results:The scanning time of single breath holding method (18 s) was significantly shorter than that of free breathing diaphragm navigation method［264（226，313）s］, and the difference between the two methods was statistically significant ( Z=-7.520， P<0.001). The SNR, CR and CNR (8.31±4.23, 0.92±0.30, 11.46±5.77) of single breath holding method were lower than those of free breathing diaphragm navigation method (11.23±5.70, 0.93±0.38, 15.06±7.37), and the differences between the two methods were also statistically significant ( t=4.378, 3.429, 4.063, P<0.05). The overall image quality, artifact, the CBD, left and right hepatic duct, right anterior and posterior branchs, the second and third branches, main pancreatic duct and cystic duct of single breath holding method were higher than those of free breathing diaphragm navigation method, and the differences between the two methods were statistically significant ( P<0.001). Conclusions:Compared with the free breathing diaphragm navigation gated 3D-SPACE MRCP imaging method, the single breath holding high parallel acquisition factor 3D-SPACE MRCP imaging method has less artifacts and examination time, but higher visibility to pancreaticobiliary tree and work efficiency, which is worthy of further promotion.

The purpose of this study was to compare the proposed rapid NT-MRCP protocol and the conventional NT-MRCP protocol with respect to image quality as well as the acquisition time. Between January 2019 and May 2019, a total number of 67 consecutive patients with suspected pancreaticobiliary diseases were included in this prospective study and underwent 3D rapid MRCP and 3D conventional MRCP sequences. Both acquisition protocols were set from the same navigator-triggered 3D SPACE sequence. The acquisition time was recorded. Two blinded radiologists performed qualitative analyses with respect to overall image quality, motion artifacts, and CBD visibility using a four-point scale. Quantitative evaluation included the contrast, signal-noise ratio (SNR), and contrast-noise ratio (CNR) between the common bile duct (CBD) and periductal tissues. A paired t test was used to assess differences in the qualitative and quantitative evaluations between the two acquisition methods. All MRCP studies were completed successfully. The mean acquisition time of rapid NT-MRCP (96.64 ± 30.55 s) was significantly lower than that of the conventional NT–MRCP (271.42 ± 61.63 s; p < 0.001).The contrast ratio, SNR, and CNR of the CBD were significantly higher for conventional NT-MRCP than with rapid NT-MRCP images (0.95 ± 0.02 vs. 0.93 ± 0.03, p < 0.001; 10.36 ± 4.63 vs. 8.90 ± 4.71, p = 0.011; 14.01 ± 6.02 vs. 12.22 ± 6.36, p = 0.020, respectively). The rapid MRCP depicted the overall image quality, artifacts, CBD visibility, right and left hepatic duct, segment 2 branch, main pancreatic duct, and cystic duct significantly better compared with conventional MRCP (p < 0.05). There were no statistically significant differences between the two methods regarding visibility of anterior, posterior, and segment 3 branches (p > 0.05). In conclusion, the proposed rapid MRCP protocol yielded significantly higher overall image quality and better visualization of the pancreaticobiliary tree with a significantly reduced imaging time without deterioration of image quality compared with the conventional MRCP at 3T.

OBJECTIVE. The purpose of this study was to evaluate the clinical feasibility of breath-hold (BH) MRCP with multichannel receiver coils in comparison with conventional navigator-triggered (NT) MRCP at 3 T. SUBJECTS AND METHODS. We prospectively studied 53 consecutive patients who underwent MRCP with BH sampling perfection with application-optimized contrasts using different flip-angle evolutions (SPACE) and NT SPACE. The acquisition time for each MRCP image was noted. The contrast ratio, the signal-to-noise ratio (SNR), and the contrast-to-noise ratio (CNR) between the common bile duct (CBD) and periductal tissues on 3D MRCP images were evaluated quantitatively. The overall image quality, motion artifacts, and CBD visibility were scored on a 4-point scale by two blinded radiologists. A paired t test was used to analyze the differences in the qualitative and quantitative evaluations between the two MRCP acquisition methods. RESULTS. Both MRCP methods were successfully performed for all subjects without any complications. The mean acquisition time of BH MRCP was significantly shorter than that of NT MRCP (18 seconds vs 264.64 ± 89.66 [SD] seconds; p < 0.001). The mean SNR, the contrast ratio, and the CNR of the CBD were significantly higher on NT MRCP images than on BH MRCP images (11.58 ± 6.24 vs 8.71 ± 4.21, 0.93 ± 0.04 vs 0.92 ± 0.03, and 15.42 ± 8.04 vs 12.00 ± 5.76, respectively; p < 0.05). All visual scores were significantly higher with BH MRCP than with conventional NT MRCP (p < 0.001). CONCLUSION. Using 3D BH MRCP with a SPACE sequence at 3 T is feasible in clinical patients, yielding significantly better perceived image quality of the pancreaticobiliary tree in a single BH (mean acquisition time, 18 seconds) without losing image quality compared with the conventional NT MRCP.