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Partial Fourier encoding is popular in single‐shot (ss) diffusion‐weighted (DW) echo planar imaging (EPI) because it enables a shorter echo time (TE) and, hence, improves the signal‐to‐noise‐ratio. Motion during diffusion encoding causes k‐space shifting and dispersion, which compromises the quality of the homodyne reconstruction. This work provides a comprehensive understanding of the artifacts in homodyne reconstruction of partial Fourier ss‐DW‐EPI data in the presence of motion‐induced phase and proposes the motion‐induced phase‐corrected homodyne (mpc‐hdyne) reconstruction method to ameliorate these artifacts. Simulations with different types of motion‐induced phase were performed to provide an understanding of the potential artifacts that occur in the homodyne reconstruction of partial Fourier ss‐DW‐EPI data. To correct for the artifacts, the mpc‐hdyne reconstruction is proposed. The algorithm recenters k‐space, updates the partial Fourier factor according to detected global k‐space shifts, and removes low‐resolution nonlinear phase before the conventional homodyne reconstruction. The mpc‐hdyne reconstruction is tested on both simulation and in vivo data. Motion‐induced phase can cause signal overestimation, worm artifacts, and signal loss in partial Fourier ss‐DW‐EPI data with the conventional homodyne reconstruction. Simulation and in vivo data showed that the proposed mpc‐hdyne reconstruction ameliorated artifacts, yielding higher quality DW images compared with conventional homodyne reconstruction. Based on the understanding of the artifacts in homodyne reconstruction of partial Fourier ss‐DW‐EPI data, the mpc‐hdyne reconstruction was proposed and showed superior performance compared with the conventional homodyne reconstruction on both simulation and in vivo data. [ABSTRACT FROM AUTHOR]

Background: With rising breast augmentations worldwide, there is an increasing clinical need for an early and accurate detection of implant complications. Purpose: To compare the quality of chemical shift encoding-based (CSE) water-fat-silicone separation compared to double inversion recovery (DIR) silicone-only imaging in breast magnetic resonance imaging (MRI). Material and Methods: This retrospective, single-center study included women with silicone implants subjected to 3-T MRI between January 2021 and March 2022. MRI included (i) two-dimensional silicone-only T2-weighted turbo spin echo DIR acquisition and (ii) three-dimensional CSE imaging based on multi-echo gradient-echo sequence enabling water-, fat-, and silicone-image separation. Images were evaluated and compared by three independent radiologists using a clinically established rating including differentiability of the silicone implant, visibility and contouring of the adjacent fibrous capsule, and accuracy of intralesional folds in a ranking of 1–5. The apparent contrast-to-noise (aCNR) was calculated. Results: In 71 women, the average quality of water-fat-silicone images from CSE imaging was assessed as "good" (assessment 4 ± 0.9). In 68 (96%) patients, CSE imaging achieved a concise delineation of the silicone implant and precise visualization of the fibrous capsule that was not distinguishable in DIR imaging. Implant ruptures were more easily detected in CSE imaging. The aCNR was higher in CSE compared to DIR imaging (18.43 ± 9.8 vs. 14.73 ± 2.5; P = 0.002). Conclusion: Intrinsically co-registered water-fat-silicone-separated CSE-based images enable a reliable assessment of silicone implants. The simultaneously improved differentiability of the implant and fibrous capsule may provide clinicians with a valuable tool for an accurate evaluation of implant integrity and early detection of potential complications. [ABSTRACT FROM AUTHOR]

Purpose: Liver T1 mapping techniques typically require long breath holds or long scan time in free‐breathing, need correction for B1+ inhomogeneities and process composite (water and fat) signals. The purpose of this work is to accelerate the multi‐slice acquisition of liver water selective T1 (wT1) mapping in a single breath hold, improving the k‐space sampling efficiency. Methods: The proposed continuous inversion‐recovery (IR) Look‐Locker methodology combines a single‐shot gradient echo spiral readout, Dixon processing and a dictionary‐based analysis for liver wT1 mapping at 3 T. The sequence parameters were adapted to obtain short scan times. The influence of fat, B1+ inhomogeneities and TE on the estimation of T1 was first assessed using simulations. The proposed method was then validated in a phantom and in 10 volunteers, comparing it with MRS and the modified Look‐Locker inversion‐recovery (MOLLI) method. Finally, the clinical feasibility was investigated by comparing wT1 maps with clinical scans in nine patients. Results: The phantom results are in good agreement with MRS. The proposed method encodes the IR‐curve for the liver wT1 estimation, is minimally sensitive to B1+ inhomogeneities and acquires one slice in 1.2 s. The volunteer results confirmed the multi‐slice capability of the proposed method, acquiring nine slices in a breath hold of 11 s. The present work shows robustness to B1+ inhomogeneities (wT1,NoB1+=1.07wT1,B1+−45.63,R2=0.99), good repeatability (wT1,2°=1.0wT1,1°−2.14,R2=0.96) and is in better agreement with MRS (wT1=0.92wT1MRS+103.28,R2=0.38) than is MOLLI (wT1MOLLI=0.76wT1MRS+254.43,R2=0.44). The wT1 maps in patients captured diverse lesions, thus showing their clinical feasibility. Conclusion: A single‐shot spiral acquisition can be combined with a continuous IR Look‐Locker method to perform rapid repeatable multi‐slice liver water T1 mapping at a rate of 1.2 s per slice without a B1+ map. The proposed method is suitable for nine‐slice liver clinical applications acquired in a single breath hold of 11 s. [ABSTRACT FROM AUTHOR]

Background: Several magnetic resonance (MR) techniques have been suggested for radiation‐free imaging of osseous structures. Purpose: To compare the diagnostic value of ultra‐short echo time and gradient echo T1‐weighted MRI for the assessment of vertebral pathologies using histology and computed tomography (CT) as the reference standard. Study Type: Prospective. Subjects: Fifty‐nine lumbar vertebral bodies harvested from 20 human cadavers (donor age 73 ± 13 years; 9 male). Field Strength/Sequence: Ultra‐short echo time sequence optimized for both bone (UTEb) and cartilage (UTEc) imaging and 3D T1‐weighted gradient‐echo sequence (T1GRE) at 3 T; susceptibility‐weighted imaging (SWI) gradient echo sequence at 1.5 T. CT was performed on a dual‐layer dual‐energy CT scanner using a routine clinical protocol. Assessment: Histopathology and conventional CT were acquired as standard of reference. Semi‐quantitative and quantitative morphological features of degenerative changes of the spines were evaluated by four radiologists independently on CT and MR images independently and blinded to all other information. Features assessed were osteophytes, endplate sclerosis, visualization of cartilaginous endplate, facet joint degeneration, presence of Schmorl's nodes, and vertebral dimensions. Vertebral disorders were assessed by a pathologist on histology. Statistical Tests: Agreement between T1GRE, SWI, UTEc, and UTEb sequences and CT imaging and histology as standard of reference were assessed using Fleiss' κ and intra‐class correlation coefficients, respectively. Results: For the morphological assessment of osteophytes and endplate sclerosis, the overall agreement between SWI, T1GRE, UTEb, and UTEc with the reference standard (histology combined with CT) was moderate to almost perfect for all readers (osteophytes: SWI, κ range: 0.68–0.76; T1GRE: 0.92–1.00; UTEb: 0.92–1.00; UTEc: 0.77–0.85; sclerosis: SWI, κ range: 0.60–0.70; T1GRE: 0.77–0.82; UTEb: 0.81–0.92; UTEc: 0.61–0.71). For the visualization of the cartilaginous endplate, UTEc showed the overall best agreement with the reference standard (histology) for all readers (κ range: 0.85–0.93). Data Conclusions: Morphological assessment of vertebral pathologies was feasible and accurate using the MR‐based bone imaging sequences compared to CT and histopathology. T1GRE showed the overall best performance for osseous changes and UTEc for the visualization of the cartilaginous endplate. Level of Evidence: 1 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]