Journal of Magnetic Resonance Imaging最新文献

Background: Impaired myocardial microvascular function may promote cardiac remodeling (CR) and myocardial fibrosis (MF), increasing cardiovascular risks in athletes. Early assessment of myocardial microcirculatory perfusion presents potential for improving athlete care.

Purpose: To evaluate the characteristics of myocardial microvascular function in athletes using resting cardiac MRI first-pass perfusion.

Study type: Prospective.

Population: One hundred and eighty-six athletes (median age 24 years, range 18-57; 167 males; mean 10 h/week exercise for 5 years) and 43 controls (median age 25 years, range 21-56; 35 males; < 3 h/week exercise).

Field strength/sequence: Balanced steady-state free precession, gradient echo sequence, and phase sensitive inversion recovery late gadolinium enhancement sequences at 3.0 T.

Assessment: CR was defined as any cardiac parameters exceeding the 99th percentile upper reference limits. MF was visually evaluated by three independent radiologists. Left ventricular resting first-pass perfusion parameters were assessed and compared across different groups. A predictive model was developed to screen athletes with and without CR/MF.

Statistical tests: Univariate analysis and Pearson coefficient were used. Area under the receiver operating characteristic curve (AUC) was used to assess the performance of the predictive model. A p < 0.05 was considered significant.

Results: Athletes exhibited lower upslope (2.12 [1.72; 2.56] vs. 2.77 [1.94; 3.22]) and maximum signal intensity (MaxSI) (20.8 [18.3; 23.6] vs. 29.5 [26.8; 33.0]), longer time to maximum signal intensity (TTM) (35.1 [31.0; 47.7] vs. 29.5 [26.8; 33.0] s) than controls. Male athletes with CR and/or MF showed lower upslope (1.54 [1.29; 1.96] vs. 1.94 [1.62; 2.43]) and MaxSI (18.0 [15.5; 21.7] vs. 21.2 [19.0; 23.5]), higher TTM (40.3 [31.5; 53.9] vs. 34.5 [29.0; 44.0] s) than those without. These perfusion parameters of athletes showed a negative correlation with global T2 mapping, QRS and corrected QT interval (r = -0.210 to -0.292). The AUC for the prediction model of CR and/or MF was 0.837.

Data conclusion: Athletes showed lower resting myocardial perfusion than controls, especially in those with CR and/or MF, suggesting an association between perfusion reduction and CR/MF.

Evidence level: 1.

Technical efficacy: Stage 2.

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Background: Accurate preoperative assessment of lymphovascular invasion (LVI) remains challenging due to the high heterogeneity of gastric cancer (GC).

Purpose: To evaluate the feasibility of a subregion-based radiomics model using multiparametric MRI (mpMRI) for preoperative evaluation of LVI and to further assess its prognostic value.

Study type: Retrospective.

Subjects: A total of 878 GC patients from four centers: 313 training, 133 internal test, and 432 external validation cases.

Field strength/sequence: 1.5 T and 3 T/mpMRI including T2-weighted imaging (FSE/TSE), diffusion-weighted imaging (SS-EPI), and contrast-enhanced T1-weighted imaging (FFE/VIBE).

Assessment: The fuzzy c-means clustering was applied to subregion generation after manual segmentation. The subregional radiomics model was established using LVI-related features from a four-step extracted pipeline, with logistic regression, random forest, and support vector machine algorithms. The corresponding intra-tumoral subregion (ITS) index for each patient was obtained from the optimal subregional model. Subsequently, a combined model incorporating the ITS index and independent clinical characteristics was developed. Performance was further validated in test and validation cohorts. Additionally, the prognostic utility for overall survival (OS) and disease-free survival (DFS) was assessed in the follow-up cohort.

Statistical tests: Model area under the receiver operating characteristic curves (AUCs) was compared using net reclassification improvement (NRI) and integrated discrimination improvement (IDI). Kaplan-Meier survival analyses were conducted for prognostic evaluation. p < 0.05 was considered statistically significant.

Results: Pathological LVI-positive was detected in 448 (51.0%) patients. The combined model demonstrated satisfactory discrimination of LVI, achieving AUCs of 0.814 (training), 0.769 (test), and 0.758-0.783 (validation), outperforming the optimal subregional model with positive NRI and IDI across all cohorts. Furthermore, the ITS index maintained a significant association with OS (HR 33.50) and DFS (HR 30.00).

Data conclusion: The combined model, which integrated the ITS index derived from subregional radiomics with clinical factors, demonstrated robust performance in evaluating both LVI and survival outcomes in GC patients.

Evidence level: 3.

Technical efficacy: Stage 3.

Background: Subamniotic or subchorionic hematoma (SAH/SCH) is associated with diverse pregnancy outcomes. The clinical implications of accompanying oligohydramnios and hemorrhagic amniotic fluid on MRI remain unclear.

Purpose: To investigate the importance of oligohydramnios and hemorrhagic amniotic fluid on placental MRI for SAH/SCH in risk stratification.

Study type: Retrospective.

Population: Seventy-one singleton pregnancies with SAH/SCH identified on placental MRI performed during the second or third trimesters, from 2016 to 2023.

Field strength/sequence: 1.5 T, Fat-saturated T1-weighted gradient echo and half-Fourier-acquired single-shot turbo spin echo sequences.

Assessment: Cases were classified into three groups: Groups A (oligohydramnios and hemorrhagic amniotic fluid), B (either oligohydramnios or hemorrhagic amniotic fluid), and C (SAH or SCH only). Groups B and C were subclassified as B-1 (oligohydramnios), B-2 (hemorrhagic amniotic fluid), C-1 (detected hematoma on ultrasound before MRI), and C-2 (incidentally detected hematoma on MRI). Unfavorable obstetric outcome (abortion or birth before 34 gestational weeks) and neonatal outcome (duration of neonatal intensive care unit [NICU] stay) were compared.

Statistical tests: Fisher's exact test, Kruskal-Wallis test, Mann-Whitney U test, and Kaplan-Meier analysis with Log-rank test. Significance was determined at p < 0.05.

Results: Unfavorable obstetric outcomes were significantly higher in Group A (11/12, 91.7%) than groups B (6/17, 35.3%) and C (9/42, 21.4%). Significant differences were found among the five subclassified groups, most notably between B-1 and B-2. The median duration of NICU stay was 87, 30.5, 0, 25, and 8 days in Groups A (n = 12), B-1 (n = 5), B-2 (n = 12), C-1 (n = 11), and C-2 (n = 31), respectively. Group A showed the worst neonatal outcomes.

Data conclusion: MRI findings of oligohydramnios and/or hemorrhagic amniotic fluid in pregnancies with SAH/SCH are associated with adverse obstetric and neonatal outcomes, supporting risk stratification.

Evidence level: 4.

Technical efficacy: Stage 5.

Background: Accurate assessment of 90-day functional outcomes after anterior circulation large vessel occlusion (LVO) stroke remains challenging. Conventional models relying on a single data dimension have limited assessment power, suggesting that a multidimensional integration strategy could enhance evaluations.

Purpose: To develop and validate an interpretable machine learning model that integrates radiomics, infarct location, brain frailty, and clinical variables for assessing 90-day functional outcomes in LVO stroke.

Study type: Retrospective.

Population: 1051 patients with anterior circulation LVO stroke (mean age 63 ± 13 years; 722 males) from five centers (2018-2023). Eight hundred and seventy-five patients from four centers formed the training (n = 612) and internal validation (n = 263) cohorts, while 176 from the fifth center comprised the external validation cohort.

Field strength/sequence: T1-weighted spin-echo imaging (T1WI), T2-weighted spin-echo imaging (T2WI), T2-weighted fluid-attenuated inversion recovery (FLAIR) imaging, and diffusion-weighted echo-planar imaging (DWI).

Assessment: Infarct volume and radiomic features were extracted from DWI. Infarct location was assessed using the Alberta Stroke Program Early CT Score. Brain frailty was evaluated using cortical/subcortical atrophy, white matter hyperintensity (WMH), and old infarcts. Least Absolute Shrinkage and Selection Operator (LASSO) regression was used for feature selection.

Statistical tests: Chi-square, Fisher's exact, t-test, Mann-Whitney U, area under the receiver operating characteristic curve (AUC), DeLong test, decision curve analysis, calibration curves, sensitivity, specificity, positive predictive value, negative predictive value, F1 score. Significance level p < 0.05.

Results: The fused model outperformed all single-dimension models (ΔAUC = 0.12-0.22), achieving AUCs of 0.87 (training), 0.84 (internal validation), and 0.86 (external validation). The fused model achieved a sensitivity and a specificity of 0.80 in the external validation cohort. Features with the highest mean absolute Shapley Additive Explanations (SHAP) values included lentiform nucleus lesion burden (SHAP = 0.083), WMH (SHAP = 0.080), and lesion burden in the M6 region (posterior middle cerebral artery territory; SHAP = 0.061).

Data conclusion: Integration of infarct location, brain frailty, radiomics, and clinical features improved the 90-day outcome assessment in anterior circulation LVO stroke, providing an interpretable tool for personalized prognosis.

Level of evidence: 3:

Technical efficacy stage: 2.