Journal of Magnetic Resonance Imaging最新文献

Background: Permanent magnet implants are used with several medical and assistive devices, such as cochlear implants, dental attachments, and prosthetic control, but raise caution for MR imaging. Previous work has evaluated several magnet implants for position and magnetization stability, as well as for image artifacts under MRI. Yet, the intramuscular magnets used for prosthetic control still require evaluation for potential MRI conditionality.

Purpose: To investigate the position and magnetization stability of and image artifacts from 3-mm-diameter spherical permanent magnets (B _r = 1.393 T, H _ci = 1.637 MA/m) implanted within muscle.

Study type: Prospective longitudinal study.

Animal model: Porcine; one animal, eight muscles.

Field strength/sequence: 0.55-T, 1.5-T/SE, GRE.

Assessment: Permanent magnets and nonmagnetic controls were implanted into eight muscles and exposed to 1.5-T MRI 36 days post-implantation. All sites were examined histologically for evidence of implant migration (acute fibrotic response or fibrotic capsule disruption). Benchtop studies evaluated worst-case demagnetization and image artifacts (artifact radius minus implant radius). The primary measure of position stability was histological examination interpreting characteristics of progressive skeletal muscle healing. Secondary position stability analysis was performed via CT imaging.

Statistical tests: Unpaired one-sided sign test with a significance level of 0.05. Demagnetization and imaging artifacts were summarized as maximums.

Results: Fibrotic capsules were similarly intact at permanent magnet and control sites (fibrotic capsule thicknesses: 20-550 μm [magnets], 20-220 μm [controls]). No effect of MRI exposure on implant migration was observed via secondary analysis (p = 0.965 [0.55-T], p = 0.996 [1.5-T]). Maximum demagnetization was 2.1% under 0.55-T exposure and 13.5% under 1.5-T exposure, and maximum image artifact was 71 mm at both imaging strengths.

Data conclusion: The permanent magnet implants used in this study were resistant to migration and substantial demagnetization under 0.55-T and 1.5-T MRI exposure and resulted in negligible image artifacts for critical organ imaging, suggesting that the presence of these implants does not preclude a patient from receiving MR imaging up to 1.5T.

Evidence level: N/A.

Technical efficacy: Stage 5: Improvements in patient care.

Background: Lack of reliable noninvasive diagnostic tools limits timely management of glomerulonephritis (GN), a major cause of chronic kidney disease.

Purpose: To validate the performance of intravoxel incoherent motion (IVIM) imaging and T2-weighted imaging (T2WI) in monitoring renal injury in rats with GN.

Study type: Prospective, animal model.

Subjects: Eighty-one Sprague-Dawley rats (54 GN, 27 control) underwent renal MRI at nine time points from Day 2 to Week 16 (GN: n = 6; control: n = 3 per time point).

Field strength/sequence: 3.0T; IVIM and T2WI.

Assessment: IVIM parameters (D, D*, f) and standardized signal intensities (SSI) on T2WI were calculated for renal cortex and outer medulla and correlated with histology.

Statistical tests: One-way analysis of variance was used for longitudinal changes and independent t-test for comparing GN and controls at each time point. Receiver operating characteristic (ROC) curve analysis assessed diagnostic performance for identifying GN.

Results: Cortex, outer stripe of outer medulla (OM) and inner stripe of the outer medulla (IM) showed early SSI increase followed by gradual decline. SSI of OM was significantly higher than controls at Days 5 (2.19 ± 0.76), 10 (2.99 ± 0.34), 15 (2.46 ± 0.37), and Week 4 (2.23 ± 0.66). In GN rats, D progressively declined from Day 2 to Week 16: from 1.51 ± 0.40 to 0.91 ± 0.45 (×10^-3 mm²/s) in cortex, and from 1.37 ± 0.23 to 0.62 ± 0.19 (×10^-3 mm²/s) in outer medulla. D* and f also decreased progressively in cortex and outer medulla. Significant inverse relationships were observed between IVIM parameters and serum biomarkers (r = -0.39 to -0.80). For diagnostic performance to identify GN, D achieved the highest area under the ROC curves in the cortex (0.926, 95% CI: 0.883-0.970) and outer medulla (0.975, 95% CI: 0.953-0.997).

Data conclusion: T2WI reveals early signal changes in GN. IVIM parameters track disease progression, correlate with serum biomarkers, and distinguish GN from healthy controls.

Level of evidence: 2:

Technical efficacy: Stage 1.

Background: Danon disease (DD), an X-linked disorder due to lysosome-associated membrane protein 2 (LAMP2) mutations, features life-threatening cardiomyopathy. Sex-based cardiac magnetic resonance (cardiac MR) differences are recognized but lack quantitative analysis despite their critical importance in establishing sex-specific diagnostic thresholds and personalized treatment strategies.

Purpose: To investigate sex-based differences in cardiac MR manifestations in DD.

Study type: Retrospective.

Subjects: 24 DD patients (15 males, 9 females; January 2018-February 2025).

Field strength/sequence: 3-T, cine imaging (gradient-echo sequence), late gadolinium enhancement (LGE) imaging (inversion-recovery gradient-echo sequence), T1 mapping (modified look-locker inversion-recovery gradient-echo sequence), T2 mapping (gradient-echo sequence with T2 preparation).

Assessment: Standardized cardiac MR assessed structural indices (LV volumes/mass, wall thickness), functional metrics (EF, strain), and tissue characterization (late gadolinium enhancement [LGE extent, T1/T2 values]).

Statistical tests: Sex comparisons used independent t-tests/Mann-Whitney U for continuous variables; Chi-square/Fisher's exact for categorical variables. p < 0.05 significant.

Results: Males predominantly developed hypertrophic cardiomyopathy (HCM: 73.3%), whereas females universally exhibited dilated cardiomyopathy (DCM: 88.9%) with preserved septal thickness. Ventricular arrhythmias occurred in all females (100% vs. 73.3% in males). Females showed significantly worse left ventricular ejection fraction (LVEF: 37.0% ± 14.0% vs. 49.9% ± 17.9%). Cardiac MR revealed extensive LGE (21.9% ± 11.4%, diffuse free-wall involvement), elevated extracellular volume (ECV) (ECV: 38% ± 12%), and significantly prolonged T1/T2 values (1374 ± 60 ms/46.5 ± 5.4 ms; T1 was higher in females). Global longitudinal strain (GLS: -6.5% ± 4.0%), radial strain (GRS: 16.9% ± 12.2%), and circumferential strain (GCS: -10.6% ± 5.7%) were reduced, with significantly worse systolic impairment in females.

Data conclusion: Sex-specific cardiac MR patterns exist in DD: males predominantly develop HCM, whereas females primarily exhibit DCM, with apical/free wall LGE observed in both sexes, though mid-basal septum sparing is more frequent in males. These findings enable sex-stratified early diagnosis and phenotype-tailored surveillance, guiding clinical management.

Evidence level: 4.

Technical efficacy: Stage 2.

Background: A comprehensive assessment of normal reference values for right atrial (RA) and right ventricular (RV) strain derived from MR-feature tracking (MR-FT) is somewhat lacking.

Purpose: To systematically review and meta-analyze reference values of RV and RA strain parameters using MR-FT in healthy adults and to identify their principal determinants.

Study type: Meta-analysis.

Population: A total of 4228 healthy adults from 40 studies (2322 male, age range: 18-79 years).

Field strength/sequence: 1.5 and 3.0 T/balanced steady-state free precession.

Assessment: A systematic search of PubMed, Embase, and Web of Science identified studies on right heart strain in healthy adults published before January 1, 2025, by two investigators. A random-effects model aggregated RV and RA strain parameters. Subgroup and meta-regression analyses assessed the effects of race, sex, age, FT software, MR vendor, and field strength.

Statistical tests: Random-effects model with pooled means and 95% confidence intervals, I ² statistic, and Egger's test. p < 0.05 was considered significant.

Results: The pooled means of RV global longitudinal, circumferential, and radial strain (RV-GLS, RV-GCS, and RV-GRS) were -22.57%, -14.16%, and 26.04%, respectively. The pooled RA reservoir, conduit, and booster strain (RA-εs, RA-εe, and RA-εa) were 47.01%, 28.24%, and 18.62%, respectively. Subgroup and meta-regression analyses identified race, sex, age, and FT software as contributing significantly to the variability in right heart measurements, while MR vendor (p = 0.437 for RV-GLS, 0.347 for RV-GCS, 0.240 for RV-GRS, 0.135 for RA-εs, 0.162 for RA-εe, and 0.287 for RA-εa) and field strength (p = 0.436 for RV-GLS, 0.041 for RV - GCS, 0.081 for RV-GRS, 0.926 for RA-εs, 0.377 for RA-εe, and 0.296 for RA-εa) had a limited impact.

Date conclusion: This study provided the pooled normal values of RV and RA strain parameters in healthy adults using MR-FT and highlighted the considerable impact of race, sex, age, and FT software on right heart strain measurements.

Level of evidence: 2:

Technical efficacy: Stage 5.

Background: Atrioventricular plane displacement (AVPD) and cardiac valve plane displacement (CVPD) are dominant contributors to the longitudinal component of ventricular pump function and vary with age; however, reference values are not available for Han Chinese adults.

Purpose: To establish reference ranges for AVPD in healthy Han Chinese adult volunteers using cardiac magnetic resonance (MR).

Study type: Prospective, single-center study.

Population: Two hundred healthy adult volunteers (45.0 ± 14.5 years; 49.5% male) were recruited between May and July 2024.

Field strength/sequence: 3.0 Tesla MR imaging; steady-state free precession (SSFP).

Assessment: All participants underwent 3.0 Tesla cardiac MR during breath-holding at end-expiration. AVPD for the left ventricle (LVAVPD) and right ventricle (RVAVPD) was quantified using three long-axis cine images with manually inputted points. LVAVPD (average (_avg), anterior (_ant), inferior (_inf), anterior-septal (_ant-sep), inferior-lateral (_inf-lat), inferior-septal (_inf-sep), anterior-lateral (_ant-lat)), as well as RVAVPD (average (_avg), right ventricular outflow tract ( _rvot ), and lateral (_lat)), were recorded.

Statistical tests: Descriptive statistics; analysis of variance for age groups; multivariate linear regression; significance was set at p < 0.05.

Results: Mean values were: LVAVPD_avg, 14.0 ± 1.5 mm; LVAVPD_ant, 12.5 ± 1.7 mm; LVAVPD_inf, 15.7 ± 2.1 mm; LVAVPD_ant-sep, 12.4 ± 2.0 mm; LVAVPD_inf-lat, 15.6 ± 2.3 mm; LVAVPD_inf-sep, 13.0 ± 1.9 mm; LVAVPD_ant-lat, 14.8 ± 2.0 mm; RVAVPD_avg, 18.7 ± 2.3 mm; RVAVPD_rvot, 20.7 ± 3.4 mm; RVAVPD_lat, 22.6 ± 3.0 mm. No significant sex differences were observed; however, significant differences were noted across the age groups (G_<45, G_45-60, and G_>60). Multivariate linear regression analysis identified age, end-diastolic volume (EDV), and end-diastolic volume index (EDVi) as significant independent determinants of AVPD.

Data conclusion: This study presents both LVAVPD and RVAVPD reference ranges in healthy Han Chinese adults and demonstrates age-related changes and correlations with EDV, stroke volume (SV), and ejection fraction (EF). These findings support the clinical utility of AVPD in myocardial function assessment.

Evidence level: N/A.

Technical efficacy: Stage 1.

Background: The loss of smell (anosmia) has been noted in numerous diseases, including COVID-19. Inflammatory and microstructural alterations are possible underlying mechanisms of anosmia in COVID-19. However, no atlas exists to study olfaction and the associated tissue property changes.

Purpose: To develop the sense of smell (SoS) atlas, including gray matter regions and white matter tracts of the olfactory circuit, to investigate the underpinnings of COVID-19 related anosmia.

Study type: Retrospective.

Subjects: For the SoS atlas, high-resolution tractograms of 10 healthy controls (HC) of the Human Connectome Project (7 females, 22-35 years) were used. The SoS atlas was applied to 8 subjects with persistent anosmia following COVID-19 (COVID-P, 7 females, 52 ± 12 years), 19 subjects that recovered from COVID-19 anosmia (COVID-R, 14 females, 38 ± 13 years), and 17 HC (8 females, 39 ± 12 years).

Field strength/sequence: 3 T, 3D inversion recovery, 3D fast field echo, and spin-echo echo-planar imaging sequences.

Assessment: To create the SoS atlas, regions were identified and tracts were extracted via tractography following biological constraints. MRI metrics sensitive to alterations in neuroinflammation, axonal degeneration, myelin and macromolecular density, and iron were analyzed.

Statistical tests: Region-based analysis (p-value < 0.05, false discovery rate (FDR) corrected) and voxel-based analysis (p-value < 0.001 uncorrected, FDR-corrected cluster extent = 5 voxels) were performed on 15 multisequence-MRI metrics between the three groups.

Results: The SoS atlas consisted of 35 regions and, after anatomical curation, the initial 506 tracts were refined to 78. Compared to HC, COVID-P presented alterations in neuroinflammation-related (mean: 41% of total alterations) and axonal degeneration-related (31%) MRI metrics, while COVID-R presented alterations of myelin-related metrics (68%). COVID-P alterations mainly affected the hindbrain (56%), while COVID-R the hindbrain (39%).

Data conclusion: A novel tool, the SoS atlas, was developed to study the olfactory system and applied in combination with multisequence-MRI metrics to investigate the mechanisms of COVID-19 related anosmia.

Evidence level: 3.

Technical efficacy: Stage 1.

Mild traumatic brain injury (mTBI) is a prevalent yet often overlooked public health concern due to the absence of detectable abnormalities on CT or conventional MRI scans. Approximately 18.3%-31.3% of mTBI patients experience persistent symptoms 3-6 months post-injury, despite normal imaging results, making diagnosis and treatment challenging. In recent years, advanced neuroimaging modalities have emerged with the potential to reveal subtle physiological and structural brain changes that are invisible to traditional imaging. Diffusion MRI (dMRI), for instance, is particularly valuable for detecting white matter injury; perfusion MRI assesses alterations in cerebral blood flow; sodium MRI (²³Na MRI) provides insights into ionic homeostasis; and functional MRI (fMRI) detects disruptions in functional brain network connectivity. In this review, we first explore the underlying mechanisms of mTBI and then summarize current evidence supporting the use of advanced MRI techniques to detect injury signatures associated with these mechanisms. Finally, we highlight populations at heightened risk for repeated injuries-underscoring the urgent need for more sensitive diagnostic tools that can identify injury early, guide return-to-activity decisions, and prevent cumulative brain damage. EVIDENCE LEVEL: N/A. TECHNICAL EFFICACY: Stage 3.