Journal of Magnetic Resonance Imaging最新文献

Background: Cardiac magnetic resonance elastography (MRE) shows promise in assessing the mechanofunctional properties of the heart but faces clinical challenges, mainly synchronization with cardiac cycle, breathing, and external harmonic stimulation.

Purpose: To determine the reproducibility of in vivo cardiac multifrequency MRE (MMRE) for assessing diastolic left ventricular (LV) stiffness and viscosity.

Study type: Prospective.

Subjects: This single-center study included a total of 28 participants (mean age, 56.6 ± 23.0 years; 16 male) consisting of randomly selected healthy participants (mean age, 44.6 ± 20.1 years; 9 male) and patients with aortic stenosis (mean age, 78.3 ± 3.8 years; 7 male).

Field strength/sequence: 3 T, 3D multifrequency MRE with a single-shot spin-echo planar imaging sequence.

Assessment: Each participant underwent two cardiac MMRE examinations on the same day. Full 3D wave fields were acquired in diastole at frequencies of 80, 90, and 100 Hz during a total of three breath-holds. Shear wave speed (SWS) and penetration rate (PR) were reconstructed as a surrogate for tissue stiffness and inverse viscous loss. Epicardial and endocardial ROIs were manually drawn by two independent readers to segment the LV myocardium.

Statistical tests: Shapiro-Wilk test, Bland-Altman analysis and intraclass correlation coefficient (ICC). P-value <0.05 were considered statistically significant.

Results: Bland-Altman analyses and intraclass correlation coefficients (ICC = 0.96 for myocardial stiffness and ICC = 0.93 for viscosity) indicated near-perfect test-retest repeatability among examinations on the same day. The mean SWS for scan and re-scan diastolic LV myocardium were 2.42 ± 0.24 m/s and 2.39 ± 0.23 m/s; the mean PR were 1.24 ± 0.17 m/s and 1.22 ± 0.14 m/s. Inter-reader variability showed good to excellent agreement for myocardial stiffness (ICC = 0.92) and viscosity (ICC = 0.85).

Data conclusion: Cardiac MMRE is a promising and reproducible method for noninvasive assessment of diastolic LV stiffness and viscosity.

Level of evidence: 2 TECHNICAL EFFICACY: 1.

Background: Intrinsic activation MR elastography (iMRE) uses cardiovascular pulsations to assess tissue viscoelastic properties. Applying it to focal liver lesions extends its capabilities.

Purpose: To assess the viscoelastic parameters of focal liver lesions measured by iMRE and compare its diagnostic performance with extrinsic MRE (eMRE) for differentiating malignant and benign lesions.

Study type: Prospective.

Population: A total of 55 participants underwent MRI with research MRE sequences; 32 participants with 17 malignant and 15 benign lesions underwent both iMRE and eMRE. FIELD STRENGTH/SEQUENCE: iMRE at ~1 Hz heart rate used a 3 T scanner with a modified four-dimensional (4D)-quantitative flow gradient-echo phase contrast and low-velocity encoding cardiac-triggered technique. eMRE employed a gradient-echo sequence at 30, 40, and 60 Hz.

Assessment: Liver displacements were measured using 4D-phase contrast and reconstructed via a nonlinear inversion algorithm to determine shear stiffness (SS) and damping ratio (DR). iMRE parameters were normalized to the corresponding values from the spleen. Lesions were manually segmented, and image quality was reviewed.

Statistical tests: Kruskal-Wallis, Mann-Whitney, Dunn's test, and areas under receiver operating characteristic curves (AUC) were assessed.

Results: SS was significantly higher in malignant than benign lesions with iMRE at 1 Hz (3.69 ± 1.31 vs. 1.63 ± 0.45) and eMRE at 30 Hz (3.76 ± 1.12 vs. 2.60 ± 1.26 kPa), 40 Hz (3.76 ± 1.12 vs. 2.60 ± 1.26 kPa), and 60 Hz (7.32 ± 2.87 vs. 2.48 ± 1.12 kPa). DR was also significantly higher in malignant than benign lesions at 40 Hz (0.36 ± 0.11 vs. 0.21 ± 0.01) and 60 Hz (0.89 ± 0.86 vs. 0.22 ± 0.09). The AUC were 0.86 for iMRE SS, 0.87-0.98 for eMRE SS, 0.47 for iMRE DR, and 0.62-0.86 for eMRE DR.

Data conclusion: Cardiac-activated iMRE can characterize liver lesions and differentiate malignant from benign lesions through normalized SS maps.

Level of evidence: 2 TECHNICAL EFFICACY: Stage 2.

Background: Women with premenstrual syndrome (PMS) are at increased risk for depression throughout their lives. White matter (WM) microstructure and inflammatory cytokine alterations have been proposed in its etiology.

Purpose: To investigate whether WM, assessed using diffusion tensor imaging (DTI), and inflammatory cytokine levels are altered in PMS, and to examine the relationships between WM microstructure, inflammatory cytokines, and symptom severity.

Study type: Prospective.

Subjects: Forty-two PMS patients and 58 healthy controls (HCs), categorized according to the daily record of severity of problems (DRSP).

Field strength/sequence: 3-T, echo planar imaging DTI.

Assessment: Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were measured by using tract-based spatial statistics (TBSS). Venous blood was collected to measure cytokines, including interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Symptoms were assessed by using the DRSP.

Statistical tests: Two-sample t test or Mann-Whitney U test were used to compare the DRSP and cytokines. Abnormal DTI metrics in WM were extracted and the differences between groups were analyzed by using two sample t-tests. Spearman's correlation (r) was used to assess the relationship between DTI metrics, cytokines, and DRSP. A P-value <0.05 with FDR correction was considered statistically significant.

Results: Compared with HCs, PMS patients showed significantly lower FA in the corpus callosum and corona radiata, and significantly higher MD, AD, and RD in the corticospinal tract (CST), and significantly higher MD and RD in the anterior thalamic radiation (ATR). These differential metrics were significantly correlated with DRSP. Patients showed significantly higher IL-1β and TNF-α than HCs. Moreover, TNF-α correlated positively with MD, AD, and RD in both groups (r range, 0.256-0.315).

Data conclusion: Alterations of WM microstructure and IL-1β and TNF-α may be associated with PMS symptom severity, and TNF-α may correlate with DTI metrics of CST and ATR pathways.

Evidence level: 1 TECHNICAL EFFICACY: Stage 2.

Background: Hyperpolarized ¹²⁹Xe MRI assesses lung ventilation, often using the ventilation defect percentage (VDP). Unlike VDP, defect distribution index (DDI) quantifies spatial clustering of defects.

Purpose: To quantify spatial distribution of ¹²⁹Xe ventilation defects using DDI across pulmonary diseases.

Study type: Retrospective.

Subjects: Four hundred twenty-one subjects (age = 23.1 ± 17.1, female = 230), comprising healthy controls (N = 60) and subjects with obstructive conditions (asthma [N = 25], bronchiolitis obliterans syndrome [BOS, N = 18], cystic fibrosis [CF, N = 90], lymphangioleiomyomatosis [LAM, N = 50]), restrictive conditions (bleomycin-treated cancer survivors [BLEO, N = 14]; fibrotic lung diseases [FLD, N = 92]), bone marrow transplantation (BMT, N = 53), and bronchopulmonary dysplasia (BPD, N = 19).

Field strength/sequence: 3 T, two-dimensional multi-slice gradient echo.

Assessment: Whole-lung mean DDI was extracted from DDI maps; correlated with VDP (percent of pixels <60% of whole-lung mean signal intensity) and pulmonary function tests (PFTs) including FEV₁, FVC, and FEV₁/FVC. DDI and DDI/VDP, a marker of defect clustering, were compared across diseases.

Statistical tests: Pearson correlation analysis and Kruskal-Wallis tests. P < 0.0056 for disease groups, P < 0.0125 for categories.

Results: DDI was significantly elevated in BMT (8.3 ± 11.5), BOS (30.1 ± 57.5), BPD (16.0 ± 46.8), CF (15.4 ± 27.2), and LAM (12.6 ± 34.2) compared to controls (1.8 ± 3.1). DDI correlated significantly with VDP in all groups (r ≥ 0.56) except BLEO, and with PFTs in CF, FLD, and LAM (r ≥ 0.56). Obstructive groups had significantly higher mean DDI (14.0 ± 32.0) than controls (1.8 ± 3.0) and restrictive groups (4.0 ± 12.0). DDI/VDP was significantly lower in the restrictive group (0.6 ± 0.6) than controls (0.8 ± 0.6) and obstructive group (1.0 ± 1.0).

Data conclusion: DDI may provide insights into the distribution of ventilation defects across diseases.

Evidence level: 3 TECHNICAL EFFICACY: Stage 2.

Background: The impact of blood-brain barrier (BBB) leakage on white matter hyperintensity (WMH) subtypes (location) and its association with clinical factors and cognition remains unclear.

Purpose: To investigate the relationship between WMH volume, permeability, clinical factors, and cognition in older individuals across the cognitive spectrum.

Study type: Prospective, cross-sectional.

Subjects: A total of 193 older adults with/without cognitive impairment; 128 females; mean age 70.1 years (standard deviation 6.8).

Field strength/sequence: 3 T, GE Dynamic contrast-enhanced, three-dimensional (3D) Magnetization-prepared rapid gradient-echo (MPRAGE T1WI), 3D fluid-attenuated inversion recovery (FLAIR).

Assessment: Periventricular WMH (PWMH), deep WMH (DWMH), and normal-appearing white matter (NAWM) were segmented using FMRIB automatic segmentation tool algorithms on 3D FLAIR. Hippocampal volume and cortex volume were segmented on 3D T1WI. BBB permeability (Ktrans) and blood plasma volume (Vp) were determined using the Patlak model. Vascular risk factors and cognition were assessed.

Statistical tests: Univariate and multivariate analyses were performed to identify factors associated with WMH permeability. Logistic regression analysis assessed the association between WMH imaging features and cognition, adjusting for age, sex, apolipoprotein E4 status, education, and brain volumes. A P-value <0.05 was considered significant.

Results: PWMH exhibited higher Ktrans (0.598 ± 0.509 × 10^-3 minute^-1) compared to DWMH (0.496 ± 0.478 × 10^-3 minute^-1) and NAWM (0.476 ± 0.398 × 10^-3 minute^-1). Smaller PWMH volume and cardiovascular disease (CVD) history were significantly associated with higher Ktrans in PWMH. In DWMH, higher Ktrans were associated with CVD history and cortical volume. In NAWM, it was linked to CVD history and dyslipidemia. Larger PWMH volume (odds ratio [OR] 1.106, confidence interval [CI]: 1.021-1.197) and smaller hippocampal volume (OR 0.069; CI: 0.019-0.253) were independently linked to worse global cognition after covariate adjustment.

Data conclusion: Elevated BBB leakage in PWMH was associated with lower PWMH volume and prior CVD history. Notably, PWMH volume, rather than permeability, was correlated with cognitive decline, suggesting that BBB leakage in WMH may be a consequence of CVD rather than indicate disease progression.

Level of evidence: 2 TECHNICAL EFFICACY: Stage 3.

Degree of Overlapped Tracts between Repeated Scans at Three GA Stages (25, 30, and 35 Weeks). Four Fiber Tracts with Significant GA Dependence in WDSC were Displayed, Each in a Representative Subject with Median WDSC of the Corresponding GA Stage. The Blue Shadings Show the Difference among Two Repeated Scans. The Warm-Colored Shadings Show the Intersection between Two Repeated Scans, Colored by the Median of WDSC Value within the GA Group. (a-d) The Reproducibility for ATR, ILF, GCC, and BCC, Respectively. The Results Indicated that WDSC Values for the Four Fiber Tracts were Higher During Early Gestational Ages (≤30 Weeks). ATR, Anterior Thalamic Radiation; ILF, Inferior Longitudinal Fasciculus; GCC, Genu of the Corpus Callosum; BCC, Body of the Corpus Callosum. By et al. (2055-2062)