Journal of Magnetic Resonance Imaging最新文献

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)

Background: Diffusion-weighted imaging (DWI) is routinely used in brain tumor surgery guided by intraoperative MRI (IoMRI). However, conventional echo planar imaging DWI (EPI-DWI) is susceptible to distortion and artifacts that affect image quality. Turbo spin echo DWI (TSE-DWI) is an alternative technique with minimal spatial distortions that has the potential to be the radiologically preferred sequence.

Purpose: To compare via single- and multisequence assessment EPI-DWI and TSE-DWI in the IoMRI setting to determine whether there is a radiological preference for either sequence.

Study type: Retrospective.

Population: Thirty-four patients (22 female) aged 2-61 years (24 under 18 years) undergoing IoMRI during surgical resection of intracranial tumors.

Field strength/sequence: 3-T, EPI-DWI, and TSE-DWI.

Assessment: Patients were scanned with EPI- and TSE-DWI as part of the standard IoMRI scanning protocol. A single-sequence assessment of spatial distortion and image artifact was performed by three neuroradiologists blinded to the sequence type. Images were scored regarding distortion and artifacts, around and remote to the resection cavity. A multisequence radiological assessment was performed by three neuroradiologists in full radiological context including all other IoMRI sequences from each case. The DWI images were directly compared with scorings of the radiologists on which they preferred with respect to anatomy, abnormality, artifact, and overall preference.

Statistical tests: Wilcoxon signed-rank tests for single-sequence assessment, weighted kappa for single and multisequence assessment. A P-value <0.001 was considered statistically significant.

Results: For the blinded single-sequence assessment, the TSE-DWI sequence was scored equal to or superior to the EPI-DWI sequence for distortion and artifacts, around and remote to the resection cavity for every case. In the multisequence assessment, all radiologists independently expressed a preference for TSE-DWI over EPI-DWI sequences on viewing brain anatomy, abnormalities, and artifacts.

Data conclusion: The TSE-DWI sequences may be favored over EPI-DWI for IoMRI in patients with intracranial tumors.

Level of evidence: 2 TECHNICAL EFFICACY: Stage 5.

Background: No study has assessed myocardial T1 and T2 values in patients with beta-thalassemia intermedia (β-TI).

Purpose: To assess the prevalence of myocardial involvement in β-TI patients by T2* relaxometry and native T1 and T2 mapping and to determine the correlation of myocardial relaxation times with demographic and clinical parameters.

Study type: Prospective matched-cohort study.

Subjects: 42 β-TI patients (27 females, 39.65 ± 12.32 years), enrolled in the Extension-Myocardial Iron Overload in Thalassaemia Network, and 42 age- and sex-matched healthy volunteers (27 females, 40.01 ± 11.36 years) and thalassemia major (TM) patients (27 females, 39.27 ± 11.57 years).

Field strength/sequence: 1.5 T/multi-echo gradient echo, modified Look-Locker inversion recovery, multi-echo fast-spin-echo, cine balanced steady-state-free precession, and late gadolinium enhancement (LGE) sequences.

Assessment: Hepatic, pancreatic, and left ventricular (LV) T2* values, LV native T1 and T2 values, biventricular ejection fractions and volumes, and presence and extent of replacement myocardial fibrosis.

Statistical tests: Comparisons between two groups were performed with two-sample t tests, Wilcoxon's signed rank tests, or χ² testing. Correlation analysis was performed using Pearson's or Spearman's test. P < 0.05 was considered statistically significant.

Results: β-TI patients had significantly higher LV T2 values than healthy subjects (56.84 ± 4.03 vs. 52.46 ± 2.50 msec, P < 0.0001) and significantly higher LV T1 values than TM patients (1018.32 ± 48.94 vs. 966.66 ± 66.47 msec, P < 0.0001). In β-TI, female gender was associated with significantly increased LV T1 (P = 0.041) and T2 values (P < 0.0001), while splenectomy and presence of regular transfusions were associated with significantly lower LV T1 values (P = 0.014 and P = 0.001, respectively). In β-TI patients, all LV relaxation times were significantly correlated with each other (T2*-T1: P = 0.003; T2*-T2: P = 0.003; T1-T2: P < 0.0001). Two patients with a reduced LV T2* also had a reduced LV T1, while only one had a reduced LV T2. Three patients had a reduced LV T1 but a normal LV T2*; 66.7% of the patients had an increased LV T2. All LV relaxation times were significantly correlated with pancreas T2* values (T2*: P = 0.033; T1: P < 0.0001; T2: P = 0.014). No LV relaxation time was associated (P > 0.05) with hepatic iron concentration, biventricular function parameters, or LGE presence.

Conclusion: The combined use of all three myocardial relaxation times has potential to improve sensitivity in the detection of early/subclinical myocardial involvement in β-Tl patients.

Level of evidence: 2 TECHNICAL EFFICACY: Stage 2.