Journal of Magnetic Resonance Imaging最新文献

Background: Access to prostate MRI remains limited due to resource constraints and the need for expert interpretation.

Purpose: To develop machine learning (ML) models that enable risk-based triage for prostate MRI (ProMT-ML) in the evaluation of prostate cancer.

Study type: Retrospective and prospective.

Population: A total of 11,879 retrospective MRI scans for suspected prostate cancer from a multi-hospital health system, divided into training (N = 9504) and test (N = 2375) sets. A total of 4551 records for prospective validation.

Field strength/sequence: 1.5T and 3T/Turbo-spin echo T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced (DCE).

Assessment: Prostate Imaging Reporting and Data System (PI-RADS) scores were retrieved from MRI reports. The Boruta algorithm was used to select final input features from candidate features. Two models were developed using supervised ML to estimate the likelihood of an abnormal MRI, defined as PI-RADS ≥ 3: Model A (with prostate volume) and Model B (without prostate volume). Models were compared to PSA. Prostate biopsy pathology was assessed to evaluate potential clinical impact.

Statistical tests: Area under the receiver operating characteristic curve (AUC) was the primary performance metric.

Results: A total of 5580 (46.9%) subjects had a PI-RADS score ≥ 3. After feature selection, Model A included age, PSA, body mass index, and prostate volume, while Model B included age, PSA, body mass index, and systolic blood pressure. Both models A (AUC 0.711) and B (AUC 0.616) significantly outperformed PSA (AUC 0.593). Compared to PSA threshold > 4 ng/mL, Model A demonstrated significantly improved specificity (28.3% vs. 21.9%) and no significant difference in sensitivity (89.0% vs. 86.7%). Among false negatives (Model A: 8.0% (62/776); Model B: 16.8% (130/776)), most (Model A: 87%; Model B: 69%) had benign or clinically insignificant disease on biopsy. On prospective validation, both versions of ProMT-ML significantly outperformed PSA.

Data conclusion: ProMT-ML provides personalized risk estimates of abnormal prostate MRI and can support triage of this test.

Level of evidence: 2:

Technical efficacy: Stage 4.

Background: Although quantitative MRI can provide objective biomarkers for brain maturation assessment, unpredictable fetal movement limits its application on fetuses.

Purpose: To evaluate single-shot multiple overlapping-echo detachment (MOLED) imaging for fetal brain T2 relaxometry and to quantify fetal brain maturation using T2 relaxation time.

Study type: Phantom and prospective in vivo assessment.

Subjects: T2 phantom and 52 fetuses (mean gestational age [GA], 30.94 ± 3.62 weeks; range, 23-37 weeks).

Field strength/sequence: 3T; half-Fourier acquisition single-shot turbo spin-echo (HASTE) and MOLED sequences.

Assessment: The accuracy, motion robustness, and repeatability of 8-s MOLED T2 relaxometry were assessed using motion-free and motion phantom acquisitions. In 15 fetuses, the MOLED scan was repeated within 5 min to assess scan-rescan repeatability. Regional T2 values were determined in fetal white matter (WM), deep gray matter (dGM) and brainstem, and their changes with GA evaluated.

Statistical tests: Bland-Altman analysis, linear regression analysis (Pearson correlation coefficient, r), coefficient of variation, repeated-measures analysis of variance, and intraclass correlation coefficient. p < 0.05 was considered statistically significant.

Results: Motion-free and motion phantom acquisitions demonstrated that MOLED T2 significantly agreed with reference T2 (r = 0.99). In vivo studies reported mean T2 values for all fetuses (WM, 215.20 ms; dGM, 145.82 ms; brainstem, 125.80 ms). Scan-rescan acquisitions showed non-significant mean T2 differences (bias < 1%; limits of agreement, -8.51% to +7.78%). Regional T2 values showed significant negative correlations (r, -0.85 to -0.60) with GA. The brainstem exhibited a significantly higher rate of GA-related T2 change (3.43 ms per week) than WM and dGM (2.19 and 2.89 ms per week, respectively).

Data conclusion: MOLED imaging appears to allow motion-robust, clinically feasible, and highly repeatable T2 measurements for the whole fetal brain in 8 s. Regional differences in T2 values and age-related T2 changes demonstrate its potential for quantifying in utero brain maturation.

Evidence level: 2.

Technical efficacy: Stage 1.

Background: A detailed evaluation of hemodynamics, supportive morphology, and deformation may help uncover the pathophysiology of hypertrophic obstructive cardiomyopathy (HOCM) and the changes wrought by alcohol septal ablation (ASA).

Purpose: To investigate the global cardiac volume, myocardial deformation, and hemodynamic characteristics before and during long-term follow-up after ASA in patients with HOCM.

Study type: Retrospective.

Subjects: Twenty-three patients (68.1 ± 8.6 years, 21.7% male) with HOCM who underwent MRI before and after ASA.

Field strength/sequence: A 3T, Two-dimensional fast imaging employing steady-state acquisition, inversion recovery-prepared fast gradient echo sequences, and cine and time-resolved three-dimensional cine phase-contrast (4D flow) MRI.

Assessment: Global left ventricular (LV) volume by cine, peak strain, and strain rate by myocardial feature-tracking MRI, and hemodynamic characteristics by 4D flow MRI.

Statistical tests: Paired t-test and Wilcoxon signed-rank test compared normally and nonnormally distributed data, respectively. Chi-squared or Fisher's exact tests were used to compare categorical data, as appropriate. Pearson's or Spearman's correlation coefficient evaluated the correlations. Statistical significance was set at q ≤ 0.10 or p < 0.05.

Results: In LV long-axis images, the global radial strain increased significantly (16.6% ± 5.8% vs. 20.1% ± 6.8%), whereas the global longitudinal strain decreased significantly after ASA (-10.5% ± 3.2% vs. -12.1% ± 3.5%). The diastolic LV anterior vortex area increased significantly after ASA (2256.1 [703.6, 4038.4] vs. 3826.1 [1914.3, 4820.1] mm²). Multiplication of the LV end-diastolic volume index, global circumferential strain, and diastolic radial peak strain rate in LV long-axis images revealed a significant correlation with the diastolic LV anterior vortex area (Rs = 0.43).

Data conclusions: Feature-tracking and 4D flow MRI revealed improved systolic and diastolic LV function during long-term follow-up after ASA. The diastolic LV vortex was associated with the combined parameters of LV volume and deformation. Comprehensive cardiac MRI may help understand the beneficial effects of ASA.

Evidence level: 3.

Technical efficacy: Stage 5.

Background: Myocardial involvement is a major manifestation of exertional heatstroke (EHS), yet its short-term clinical outcome remains unclear.

Purpose: To assess serial cardiac left ventricular structural and functional changes using baseline and 3-month cardiac MRI.

Study type: Prospective.

Population: A total of 41 participants (median age, 21 years; IQR, 20-23 years) hospitalized for EHS and 27 age-, sex-, and training-matched healthy controls (HCs).

Field strength/sequence: Fast imaging employing steady-state acquisition (cine imaging), saturation methods using adaptive recovery times (native T1, extracellular volume [ECV]), phase-sensitive inversion-recovery gradient recalled echo (late gadolinium enhancement [LGE]), and multi-echo fast spin echo (T2) sequences at 3.0 T.

Assessment: Longitudinal comparisons were performed within the EHS group (baseline vs. 3-month follow-up), and cross-sectional comparisons were performed between patients and HCs. Cardiac symptoms (chest pain, dyspnea, palpitations, and syncope) at follow-up were recorded using standardized questionnaires.

Statistical tests: Paired sample t-test, independent sample t-test, analysis of variance, Kendall's τ-b. A p value < 0.05 was considered significant.

Results: Significant improvements were observed in native T1 (1492 ± 52 ms vs. 1521 ± 57 ms), ECV (23.4% ± 1.7% vs. 24.3% ± 1.8%), T2 (45.9 ± 2.2 ms vs. 47.3 ± 2.3 ms), and 2D global longitudinal strain (-16.7% ± 1.6% vs. -15.8% ± 1.1%) at 3 months follow-up compared to baseline parameters in the EHS cohort. However, native T1 (1492 ± 52 ms vs. 1456 ± 26 ms) and ECV (23.4% ± 1.7% vs. 20.6% ± 1.6%) at follow-up were significantly higher in EHS than in HCs. At 3-month follow-up, native T1, ECV, and LGE presence were associated with cardiac symptoms (Kendall's τ-b = -0.430, -0.447, and -0.398, respectively).

Data conclusion: This study demonstrated persistently elevated native T1 and ECV at 3 months following EHS, despite partial improvement. Those with residual abnormalities should not be cleared for unrestricted training.

Evidence level: 2.

Technical efficacy: Stage 2.