Journal of Magnetic Resonance Imaging最新文献

Background: Three-dimensional MR fingerprinting (3D-MRF) has been increasingly used to assess cartilage degeneration, particularly in the knee joint, by looking into multiple relaxation parameters. A comparable 3D-MRF approach can be adapted to assess cartilage degeneration for the hip joint, with changes to accommodate specific challenges of hip joint imaging.

Purpose: To demonstrate the feasibility and repeatability of 3D-MRF in the bilateral hip jointly we map proton density (PD), T₁, T₂, T_1ρ, and ∆B₁₊ in clinically feasible scan times.

Study type: Prospective.

Subjects: Eight healthy subjects, three patients with mild osteoarthritis (OA), and one of the OA patients had femoral acetabular impingement (FAI). A National Institute of Standards and Technology/International Society for Magnetic Resonance in Medicine (NIST/ISMRM) system phantom was also used.

Field strength/sequence: 3 T, 3D-MRF sequence for bilateral hip joint mapping. Reference sequences include Volume Interpolated Breath-hold Examination (VIBE) for T₁ mapping, and magnetization-prepared fast low-angle shot (TFL) for T₂ and T_1ρ mapping.

Assessment: The signal-to-noise ratio (SNR), repeatability, scan time, and accuracy of T₁, T₂, and T_1ρ maps of 3D-MRF sequence were evaluated on a NIST/ISMRM phantom and human subjects. Differences in the parametric maps between OA and healthy subjects were assessed.

Statistical tests: Regression, Bland-Altman, Kruskal-Wallis, and Wilcoxon tests were used to assess for accuracy, repeatability, and subregional variation. The P-value <0.05 indicated statistically significant.

Results: A 3D-MRF sequence sensitive to PD, T₁, T₂, T_1ρ, and ∆B₁₊ within 15 minutes, achieving high SNR and low test-retest coefficient of variance (T₁: 3.36%, T₂: 3.99%, T_1ρ: 5.93%). Mild hip OA patients, including one with mild OA and FAI, showed elevation of 29.4 ± 9% (T₂) and 32.4 ± 4.4% (T_1ρ) in femoral lateral compartment of the hip joint compared to healthy controls.

Data conclusion: 3D-MRF may be a feasible approach for simultaneous, quantitative mapping of bilateral hip joint cartilage in healthy and mild OA patients.

Evidence level: 1 TECHNICAL EFFICACY: Stage 1.

The acoustic noise outputs of MR equipment typically require a hearing protection device (HPD) to minimize the likelihood of patient hearing loss. Several different ways to quantify HPD performance have been developed and adopted over many years in different countries across the world (eg, NRR, SNR, SLC80). These HPD evaluations are done in controlled laboratory conditions, following different standardized methodologies, producing different performance ratings for the same HPD, and consequently of a variable relationship with achieved real-world usage performance assessments. Conversely, the MR manufacturers follow one standard (NEMA MS-4) which strives to produce a worst-case peak and average acoustic noise output measurement. Measuring the acoustic output of MR equipment is a complex undertaking in the confined patient space, especially when considering the variability of what is in the patient imaging space. Given both the MR equipment acoustic output measurements and the HPD performance rating, it is theoretically possible to estimate the worst-case patient exposure level, subject to the uncertainty of how successfully the protection was applied and population variability. An assessment, shown here, suggests that the worst-case outputs from the loudest MR equipment requires the best passive HPD performance presently available in order to meet patient protection guidelines, but only when the HPD is properly deployed. However, when considering government agency derating recommendations that estimate protection achieved during practical application, the various metrics are not consistent in confirming that the best HPD provide sufficient protection. This paper reviews the challenges of determining and providing sufficient hearing protection. The correct deployment of HPD, and its verification, is thus a critical factor in ensuring adequate patient protection and the main concern of this review. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 5.

Background: Previous studies have shown neurovascular coupling (NVC) dysfunction in epilepsy, suggesting its role in the pathological mechanisms. However, it remains unclear whether NVC abnormalities exist in epilepsy of unknown etiology (EU).

Purpose: To integrate multiparametric MRI to assess NVC and its relationship with cognition in early-onset and late-onset EU patients.

Study type: Prospective.

Population: Ninety-six EU patients (46 early-onset, M/F = 20/26; 50 late-onset, M/F = 29/21) and 60 healthy controls (HCs, M/F = 25/35).

Field strength/sequence: 3.0 T, resting-state gradient echo-planar imaging, pseudo-continuous arterial spin labeling (pc-ASL), and T1-weighted brain volume sequence.

Assessment: Functional MRI data were analyzed to assess intrinsic brain activity including amplitude of low-frequency fluctuations (ALFF), fractional ALFF (fALFF), regional homogeneity (ReHo), and functional connectivity strength (FCS), while pc-ASL provided cerebral blood flow (CBF) measurements. Coupling correlation coefficients and ratios of CBF to neural activity were calculated to evaluate global and regional NVC.

Statistical tests: Two-sample t-test, Analysis of Variance, Kruskal-Wallis test, Chi-square test, Analysis of Covariance, family-wise error/Bonferroni correction, partial correlation analyses. Statistical significance was defined as P < 0.05.

Results: Whole-brain analysis revealed increased ALFF values in both patient groups' left precentral and postcentral gyri. Both patient groups had lower global NVC coefficients than HCs, with reduced CBF-ALFF (0.28 vs. 0.30), CBF-fALFF (0.43 vs. 0.45), and CBF-ReHo (0.40 vs. 0.41) in early-onset patients, and lower CBF-fALFF (0.38 vs. 0.45) and CBF-ReHo (0.32 vs. 0.41) in late-onset patients. Regional analysis showed significantly decreased CBF/ALFF ratios in the left precentral and postcentral gyri (T = 3.85 to 5.33). Reduced global NVC in early-onset patients was significantly associated with poorer executive function (r = 0.323), while global coupling in late-onset patients was negatively correlated with disease duration (r = -0.348 to -0.426).

Data conclusion: This study showed abnormal global and regional NVC in both early-onset and late-onset EU patients, emphasizing the potential role of NVC in the pathophysiological mechanisms of EU.

Level of evidence: 1 TECHNICAL EFFICACY: Stage 1.

SHOWS STRUCTURAL IMAGES AND VARIOUS PARAMETER MAPS COMPUTED USING FIRST-PASS ANALYSIS, CTUM AND PATLAK-MODEL (B–J) IN A PATIENT WITH IDH WILD TYPE GLIOBLASTOMA. (A) POSTCONTRAST T1-W, (B) RCBF, (C) RCBV, (D) FLAIR, (E) RCBF_CORR, (F) RCBV_CORR, (G) RVP (PATLAK-MODEL), AND (H) RFP. CTUM= COMPARTMENTAL TISSUE UPTAKE MODEL; CBV = CEREBRAL BLOOD VOLUME; CBF = CEREBRAL BLOOD FLOW (CBF); CBV_CORR = LEAKAGE CORRECTED CBV; CBF_CORR = LEAKAGE CORRECTED CBF (R REPRESENTS NORMALIZED WITH RESPECT TO NORMAL-APPEARING WM). BY SANKARALAYAM ET AL. (509-511)

Background: Selective inversion recovery quantitative magnetization transfer (SIR-qMT)-derived macromolecular to free water pool size ratio (PSR) and diffusion tensor imaging (DTI)-derived radial diffusivity (RD) are potential metrics for assessing myelin integrity in multiple sclerosis (MS). However, establishing their accuracy in identifying tissue injury is essential for clinical translation.

Purpose: To compare the accuracy and Cohen's effect size (ES) of PSR and RD in detecting and quantifying tissue injury in early MS.

Study type: Cross-sectional prospective study.

Subjects: Fourty-three subjects with newly diagnosed MS (mean age 38 ± 11 years, 70% females) and 18 age- and sex-matched healthy controls (HCs; age 38 ± 12 years, 62.5% females).

Field strength/sequence: 3-T MRI using T₁-weighted (T₁-w) turbo spin echo, T₂-w fluid-attenuated inversion recovery (FLAIR), DTI, and SIR-qMT sequences.

Assessment: T₂-lesions were identified as hyperintense on T₂-w-FLAIR, and chronic black holes (cBHs) by simultaneous T₂-w-FLAIR hyperintensity and T₁-w hypointensity. Regions of interest (ROIs) in normal-appearing white matter (NAWM) were classified as proximal (p) or distant (d) to lesions, while normal white matter (NWM) was identified in HCs. PSR and RD values of T₂-lesions and cBHs were compared to their matched p/dNAWM and NWM in HCs. Comparisons were also made between T₂-lesions and cBHs.

Statistical tests: Receiver operating characteristic curves evaluated metric accuracy, and paired t tests compared ES values of PSR and RD, with significance set at P < 0.050.

Results: We identified 823 T₂-lesions, 392 cBHs, 426 p-, and 213 d-NAWM ROIs in patients, and 162 NWM ROIs in HCs. PSR differed significantly in all comparisons, while RD was differed in all except cBHs vs. T₂-lesions (P = 0.051). PSR had significantly higher accuracy in differentiating T₂-lesions from p/dNAWM and NWM, with a larger ES when comparing T₂-lesions to p/dNAWM and NWM and cBHs to pNAWM and NWM.

Data conclusion: PSR offers superior accuracy and ES over RD in detecting tissue injury in MS.

Level of evidence: 1 TECHNICAL EFFICACY: Stage 2.

Background: Pediatric brain cancer survivors often experience hypothalamic-pituitary dysfunction due to cranial irradiation and chemotherapy. While hormone deficiencies have been studied, the changes in pituitary size and shape on long-term MRI and their relationship to endocrine dysfunction remain under-explored.

Purpose: To evaluate pituitary gland height, volume, and shape in relation to long-term endocrine abnormalities in pediatric brain tumor survivors.

Study type: Retrospective cohort study.

Population: A total of 56 pediatric brain tumor survivors (50% male) with an average follow-up of 10.8 ± 1.6 years; 44.6% underwent radiotherapy, and 48% were treated with chemotherapy. One-third of the cohort experienced at least one pituitary hormone deficiency.

Field strength/sequence: 3 T, including volumetric 1 mm sagittal post-contrast T1 images.

Assessment: Pituitary height, volume, and shape (concave, horizontal, convex) were measured. Endocrine abnormalities were diagnosed through routine serum hormone testing.

Statistical tests: The t test, chi-square test, and Pearson test with significance at P < 0.05 were used. Receiver-operating characteristic (ROC) analysis assessed the association of imaging parameters and pituitary dysfunction.

Results: Radiation and chemotherapy treatment were significantly associated with pituitary hormone deficiencies. There were significant differences in pituitary height and volume in patients with pituitary hormone deficiencies compared with normal pituitary function (4.0 ± 1.3 vs. 5.5 ± 1.5 mm, and 354.2 ± 198.0 vs. 568.3 ± 184.4 mm³, respectively). There was a significant association between radiation therapy and pituitary gland shape, with 60.0% of patients who received radiation therapy exhibiting a pituitary shape categorized as concave, 32.0% as horizontal, and 8.0% as convex, compared to 9.7%, 74.2%, and 16.1%, respectively. ROC analysis for association with pituitary hormone deficiency was 0.81, 0.8, and 0.74 for pituitary height, volume, and shape, respectively.

Data conclusion: Cranial irradiation and chemotherapy in pediatric brain tumors are associated with endocrine dysfunction, with decreased pituitary height, volume, and concave shape in long-term MRI surveillance are associated with such late endocrine dysfunction.

Level of evidence: 4 TECHNICAL EFFICACY: Stage 2.

Background: Neurite orientation dispersion and density imaging (NODDI) could offer information about the morphological properties of tissue. Diffusion microstructure imaging has been widely used, but the applicability of NODDI in skeletal muscle imaging remains to be explored.

Purpose: To evaluate microstructure parameters variations in skeletal muscle as indicators of age-related changes.

Study type: Prospective, cross-sectional.

Population: A total of 108 asymptomatic volunteers, divided into three age groups: 20-39 years (N = 34), 40-59 years (N = 40), and over 60 years (N = 34).

Field strength/sequence: 3-T, three-dimensional (3D) gradient echo sequence.

Assessment: T1-weighted imaging, T2-weighted imaging with spectral adiabatic inversion recovery, and NODDI were used to image the thigh skeletal muscles. Four thigh skeletal muscle groups were analyzed, including bilateral thigh quadriceps femoris and hamstrings. The microstructure parameters included orientation dispersion index (ODI), intra-myofibrillar water volume fraction (V-intra), free-water fraction (V-csf), fractional anisotropy (FA), and mean diffusivity (MD). These parameters were quantified using NODDI images and compared among different age, body mass index (BMI), and skeletal muscle index (SMI) subgroups.

Statistical tests: Segmentation measurement reliability was assessed using a two-way mixed intraclass correlation coefficient (ICC). Shapiro-Wilk tests were used to assess data distribution. Kruskal-Wallis and Mann-Whitney U tests were used to compare ODI, V-intra, V-csf, FA, and MD values among different age, BMI, and SMI subgroups. The Spearman correlation coefficient was utilized to assess the strength of the correlation between the age and microstructure parameters, as well as between age and SMI. Additionally, Bonferroni post hoc tests were conducted on microstructure parameters that exhibited significant differences across various age groups. A P-value <0.05 was considered statistically significant.

Results: Significant differences in ODI, V-csf, FA, and MD values were observed among age, BMI, and SMI subgroups.

Data conclusion: NODDI may be used to reveal information about microstructure integrity and local physiological changes of thigh skeletal muscle fibers in relation to age.

Level of evidence: 2 TECHNICAL EFFICACY: Stage 2.