Journal of Magnetic Resonance Imaging最新文献

Background: MR-generated acoustic noise may be particularly concerning at 7-Tesla (T) systems. Noise levels can be reduced by altering gradient output using software optimization. However, such alterations might influence image quality or prolong scan times, and these optimizations have not been well characterized.

Purpose: To evaluate image quality, sound pressure levels (SPLs), and perceived noise levels when using the acoustic noise reduction technique SofTone for T₂-weighted fast spin echo (T₂W FSE) and three-dimensional T₁-weighted turbo field echo (3D T₁W TFE), and to compare with conventional imaging during 7-T brain MRI.

Study type: Prospective.

Subjects: Twenty-eight volunteers underwent brain MRI, with n = 26 for image quality evaluations.

Field strength/sequence: Conventional and SofTone versions of T₂W FSE and 3D T₁W TFE at 7 T.

Assessment: Peak SPLs (A-weighted decibels, dBA), participant-perceived noise levels (Borg CR10-scale), qualitative image assessments by three neuroradiologists (four-graded ordinal scales), interrater reliability, and percentage agreement.

Statistical test: Paired t-test, Wilcoxon's Signed-Rank Test, and Krippendorff's alpha; p < 0.05 were considered statistically significant.

Results: SofTone significantly reduced peak SPLs: from 116.3 to 97.0 dBA on T₂W FSE, and from 123.7 to 101.5 dBA on 3D T₁W TFE. SofTone was perceived as significantly quieter than conventional scanning. T₂W FSE showed no significant differences in image quality assessments (p = 0.21-1.00), except one radiologist noting significantly less artifact interference with SofTone. General image quality remained acceptable for 3D T₁W TFE, though one radiologist scored it significantly lower with SofTone (mean scores: 3.08 vs. 3.65), and two radiologists observed significantly worse white and gray matter differentiation with SofTone (mean scores: 3.19 vs. 3.54; 2.27 vs. 2.81).

Data conclusion: SofTone can significantly reduce sound intensity and perceived noise levels while maintaining acceptable image quality with T₂W FSE and 3D T₁W TFE in brain MRI. It appears to be an effective tool for providing a safer, quieter 7-T scan environment.

Evidence level: 4 Technical Efficacy: Stage 5.

Hepatic steatosis is a common imaging finding that can be a sign of chronic liver disease, most often associated with metabolic dysfunction-associated steatotic liver disease (MASLD). Imaging techniques for evaluating steatosis range from basic qualitative assessments to advanced and highly accurate quantitative metrics. Among these, MRI-based proton density fat fraction (PDFF) is widely regarded as a reliable and precise imaging biomarker for quantifying liver steatosis. Additionally, multiple ultrasound platforms now offer quantitative assessments of hepatic steatosis. These methods include attenuation coefficient, speed of sound, backscatter, or other multiparametric approaches such as ultrasound-derived fat fraction (UDFF) which combines attenuation and backscatter quantification. Newer and upcoming quantitative ultrasound methods include acoustic structure quantification (ASQ) and tissue scatter distribution imaging (TSI). Therefore, ultrasound-based liver fat measurements could potentially serve as an effective screening tool in certain clinical settings, such as suspected MASLD. In this review, we describe how, why, and when to use MRI- and ultrasound-based fat quantification techniques for assessing liver steatosis in children. We discuss practical strategies for adapting and optimizing these methods in pediatric settings, considering clinical indications, patient preparation, equipment needs, acquisition techniques, potential pitfalls, and confounding factors. Additionally, guidance is provided for interpretation and reporting, along with illustrative case examples. Evidence Level: N/A Technical Efficacy: Stage 5.

Background: Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD), the most common dystrophinopathies, require distinct treatments. Corticosteroids are effective for DMD but less so for BMD. Early diagnosis can improve DMD outcomes and prevent BMD overtreatment. However, differentiating them in younger children with mild symptoms is challenging due to overlapping features.

Purpose: To evaluate the performance of multi-parametric quantitative MRI (qMRI) in early differentiation between BMD and DMD, particularly among younger patients in the mild disease stage.

Study type: Prospective.

Subjects: 121 DMD males (mean age 8.5 ± 1.6 years), 28 BMD males (9.7 ± 3.3 years), and 26 male healthy controls (HCs) (9.4 ± 2.7 years).

Field strength/sequence: 3.0T/3-point Dixon (fast-spin-echo), T1-mapping (modified-Look-Locker-inversion-recovery), and T2-mapping (balance-steady-state-free-precession).

Assessment: qMRI measurements (fat fraction [FF], T1, and T2) in 18 pelvic and thigh muscles were conducted. A linearized NorthStar ambulatory assessment (NSAA) score was used to evaluate the function status, with a mild functional decline stage defined as a score of 76-100.

Statistical tests: Mann-Whitney test, Kruskal-Wallis test, and Receiver operating characteristic curves. A P-value < 0.05 was considered statistically significant.

Results: In all subject groups, DMD exhibits significantly higher FF and T2 and lower T1 compared to BMD. The max differences in mean FF, T1, and T2 was 45.29%, 543 ms, and 31.0 ms, respectively. Overall, the area under curve (AUC) values for FF surpassed those for T2 and T1 in the majority of muscles. In the mild subgroup below 10 years old, DMD had significantly higher FF and T1 than BMD. The combination of FF and T1 in gluteus medius, rectus femoris, vastus lateralis, vastus intermedius, vastus medialis, and adductor magnus achieved higher AUCs (0.816-0.957) than FF (0.773-0.862) or T1 (0.701-0.819) in differentiating the two subgroups.

Data conclusion: Multi-parametric qMRI demonstrates potential as an effective tool for early differentiation between DMD and BMD.

Evidence level: 2 TECHNICAL EFFICACY: Stage 3.

Hyperpolarized (HP) gas pulmonary MR ventilation images are typically quantified using ventilation defect percent (VDP); however, the test-retest variability of VDP has not been systematically established in multi-center trials. Herein, we perform a systematic review of the test-retest literature on the variability of VDP, and similar metrics, generated from HP MRI. This review utilizes the Medline, EMBASE, and EBM Reviews databases and includes studies that assessed the variability of HP MRI VDP. The protocol was registered to PROSPERO: CRD42022328535. Imaging techniques and statistical analysis characteristics were extracted and used to group studies to evaluate the overall ability to pool data across grouped studies. The ability to pool data to provide systematic evidence was assessed using a modified COSMIN tool. A total of 22 studies with 37 distinct aims for repeated HP MRI acquisition or quantification were included. Studies were grouped into six categories based on HP gas and analysis type: repeated imaging (¹²⁹Xe n = 13, ³He n = 12), interobserver repeated analysis (¹²⁹Xe n = 4, ³He n = 4) or intraobserver repeated analysis (¹²⁹Xe n = 1, ³He n = 2). Studies assessed variability using a variety of statistical tests including absolute difference, percent coefficient of variation, Bland-Altman limits of agreement, coefficient of reproducibility, or the intra-class correlation. Individual studies generally reported low variability of VDP (ICC range: 0.5-1.0; Bland-Altman bias range: -6.9-20%), but there was an overall inability to pool data and provide a meta-analysis due to methodological inconsistencies and small sample size. Overall, we found that VDP has low variability in most studies. However, inconsistent image acquisition and quantification methodologies between studies limits direct comparability and precludes grouping of study data for meta-analyses. Despite early efforts to standardize HP MRI acquisition, further work is necessary to standardize VDP quantification to allow broader validation and clinical implementation. Evidence Level: 2 Technical Efficacy: Stage 3.

The American College of Radiology Liver Imaging Reporting and Data System (LI-RADS) is the preeminent framework for classification and risk stratification of liver observations on imaging in patients at high risk for hepatocellular carcinoma. In this review, the pathogenesis of hepatocellular carcinoma and the use of MRI in LI-RADS is discussed, including specifically the LI-RADS diagnostic algorithm, its components, and its reproducibility with reference to the latest supporting evidence. The LI-RADS treatment response algorithms are reviewed, including the more recent radiation treatment response algorithm. The application of artificial intelligence, points of controversy, LI-RADS relative to other liver imaging systems, and possible future directions are explored. After reading this article, the reader will have an understanding of the foundation and application of LI-RADS as well as possible future directions.

Magnetic resonance imaging (MRI) has recently emerged as a promising modality for dental applications, offering radiation-free imaging with superior soft tissue visualization capabilities compared to x-ray-based techniques such as spiral or cone beam computed tomography (CBCT). Conventional radiographic methods or CBCT cannot directly assess the condition of the dental pulp due to their primary focus on hard tissue visualization, whereas the dental pulp is primarily composed of connective tissue. Given the advantages of MRI in soft tissue imaging, this review aims to explore the current application of MRI for dental pulp tissue assessment. Relevant studies concerning the application of MRI for visualizing dental pulp were retrieved from databases including PubMed, Embase, and Scopus. The review explored and discussed the advancements in MRI hardware and software related to dental pulp visualization, as well as the advantages and limitations of MRI in dental pulp studies. Despite remaining limitations, such as scanning time and cost considerations, MRI offers notable benefits, including radiation-free imaging and potentially superior resolution and accuracy compared with other imaging techniques. Consequently, the continued advancement of MRI as a noninvasive diagnostic method in dentistry, particularly for assessing pulp condition, holds substantial promise for improving endodontic diagnosis and subsequent treatment decision-making.