Journal of Magnetic Resonance Imaging最新文献

Background: FDG-PET aids presurgical epilepsy evaluation but is limited by access and radiation exposure.

Purpose: To evaluate synthetic FDG-PET generated from T1-weighted imaging and resting-state fMRI metrics.

Study type: Retrospective.

Population: 481 participants underwent simultaneous FDG PET/MR. Internal cohort: 311 epilepsy patients split into training/validation/internal test sets (n = 249/31/31; age 18.79 ± 16.33/22.20 ± 11.21/21.65 ± 17.62 years; male/female 145/104, 13/18, 22/9). External cohort: 115 temporal lobe epilepsy patients (age 25.36 ± 10.95 years; male/female 68/47) and 55 healthy controls (age 27.62 ± 5.82 years; male/female 24/31); 92 had surgery with 1-year outcome.

Field strength: Hybrid PET/MR at 3.0 T; gradient-echo T1WI, echo-planar imaging and resting-state BOLD gradient-echo EPI.

Assessment: Performance was assessed using SSIM, PSNR, MSE, NRMSE, SUVR correlation, and Bland-Altman analysis. Three blinded readers performed visual quality grading and detection of temporal lobe hypometabolism. Hippocampal radiomics was used for classification of hippocampal sclerosis and Engel outcome.

Statistical tests: t-tests, chi-square tests, Pearson correlation, Kolmogorov-Smirnov tests, DeLong tests, and false discovery rate correction.

Results: Excellent/Good visual ratings occurred in 82.8% (166/201), with Fleiss' κ = 0.42. SSIM was 0.98 ± 0.01 (internal) and 0.97 ± 0.01 (external); PSNR was 66.66 ± 1.25 and 64.16 ± 1.83, respectively. SUVR correlation with ground-truth PET was r = 0.94 (internal) and r = 0.89 (external); Bland-Altman bias was -0.02 (95% limits of agreement: -0.22 to 0.18) internally and -0.00002 (95% limits: -0.35 to 0.35) externally. Detection accuracy for temporal hypometabolism was 90.3% (internal; κ = 0.735) and 87.1% (external; κ = 0.758). Radiomics AUCs using synthetic PET were 0.72 (95% CI: 0.62-0.83) for hippocampal sclerosis versus healthy controls and 0.77 (95% CI: 0.67-0.87) for Engel IA versus IB-IV; DeLong tests versus ground-truth PET were non-significant (p = 0.56 and p = 0.48).

Conclusion: Multisequence MRI-based synthetic PET showed high agreement with ground-truth PET across image-quality and quantitative SUVR metrics, providing a PET-like metabolic surrogate when FDG-PET is unavailable or impractical.

Level of evidence: Evidence Level 3.

Stages of technical efficacy: Stage 3.

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.

Background: Autism Spectrum Disorder (ASD) presents with early neurodevelopmental alterations in preschool children, yet comprehensive characterization using multimodal quantitative MRI remains limited in this age group.

Purpose: To investigate voxel-wise brain microstructural differences in preschool ASD through integrated analysis of cerebral perfusion, multiparametric relaxometry, and magnetic susceptibility.

Study type: Prospective case-control.

Population: Twenty nine-children with ASD (age 2-6 years; 23 males/6 females) and 25 age-/sex-matched healthy controls (HC).

Field strength/sequence: 3.0 T MRI; high-resolution 3D-T1WI, quantitative susceptibility mapping (QSM), synthetic MRI (SyMRI), 3D pseudo-continuous arterial spin labeling (3D-pCASL).

Assessment: Clinical assessments included the Gesell Developmental Schedules (GDS) and Childhood Autism Rating Scale (CARS). Imaging analysis consisted of voxel-wise whole-brain assessment of QSM, T1/T2/PD, and cerebral blood flow (CBF) maps.

Statistical tests: General linear models with cluster-based thresholding were applied for group comparison; Spearman's rank correlation with Bonferroni correction was used for clinical associations; and receiver operating characteristic (ROC) analysis with Delong's test was performed to compare diagnostic performance based on the areas under the curve (AUCs).

Results: Compared to HC, children with ASD showed decreased QSM values in the left superior/middle frontal gyri (SFG/MFG; cluster = 212 voxels, peak T = 5.55, p < 0.001). They also had reduced T1 relaxation times in bilateral SFG/MFG/precentral/postcentral gyri (four clusters: 315-750 voxels, peak T = 5.11-5.88, all p < 0.001). QSM values in the left SFG/MFG correlated positively with fine motor scores (r = 0.630, p < 0.001), while T1 values in the bilateral precentral/postcentral gyri correlated with gross motor scores (right: r = 0.548, p = 0.002; left: r = 0.461, p = 0.012). ROC analysis showed high diagnostic accuracy for both QSM (left SFG/MFG AUC = 0.858) and T1 values (left SFG/MFG AUC = 0.905; bilateral precentral/postcentral gyri AUC = 0.892-0.908).

Data conclusion: Preschool ASD demonstrates prefrontal iron deficiency (reduced QSM) and sensorimotor myelination alterations (decreased T1), which correlate with motor deficits and show high diagnostic efficacy.

Evidence level: 2.

Technical efficacy: Stage 2.

Background: Patients with solid renal masses (SRMs) are at risk of chronic kidney disease (CKD) after surgical resection without a reliable pre-operative predictor.

Purpose: To investigate whether pre-operative multiparametric MRI (mpMRI) can predict CKD development and progression to stage 3 CKD.

Study type: Prospective.

Population: Forty-three participants (female = 13, mean age: 59 ± 12 years) undergoing nephrectomy for SRM.

Field strength/sequence: 1.5 T, diffusion-weighted echo-planar imaging (DWI) using nine b-values (0-800 s/mm²), T₁-mapping using variable flip angle, multi-echo gradient-echo blood-oxygen-level-dependent (BOLD), and dynamic-contrast-enhanced MRI (DCE-MRI) using 3D T₁-weighted gradient-echo.

Assessment: A clinical CKD risk score was calculated from estimated glomerular filtration rate (eGFR), age, diabetes, and surgery (partial or radical nephrectomy). mpMRI parameters included cortical and medullary apparent diffusion coefficient (ADC), intravoxel incoherent motion (IVIM), tri-exponential diffusion (fast, medium, and slow), and spectral diffusion (vascular, tubule, and tissue) from DWI, native T₁ from T₁-mapping, R₂* from BOLD, and renal plasma flow and eGFR from DCE-MRI. Outcomes were a correlation with baseline eGFR, prediction of postoperative 12-month eGFR decline > 5 mL/min/1.73 m², and stage 3 CKD development (eGFR < 60 mL/min/1.73 m²).

Statistical tests: Mann-Whitney U-test and Spearman's rank correlation coefficient (r). Diagnostic ability was determined by leave-one-out cross-validated logistic regression area-under-the-receiver-operator-curve (AUC) and diagnostic odds ratio (DOR) with p-value < 0.05 considered significant.

Results: Thirty of 43 (67%) participants had normal baseline renal function (eGFR ≥ 60 mL/min/1.73 m²). Twenty-nine participants completed 12-month follow-up: among 66% (19/29) who had baseline normal eGFR, 37% (7/19) developed stage 3 CKD. eGFR from DCE-MRI and tubule diffusion correlated with baseline eGFR ( $r^2$ = 0.43 and 0.33 respectively). Reduced vascular diffusion predicted eGFR decline (AUC = 0.75-0.83, DOR = 6.8-16.5). A larger contralateral ADC corticomedullary difference (AUC = 0.89; DOR = 22.5), and clinical CKD risk score (AUC = 0.81; DOR = 5.5) were the strongest predictors of CKD development.

Data conclusion: Pre-operative mpMRI predicted post-nephrectomy CKD development. A larger corticomedullary difference in ADC may indicate reduced functional reserve.

Evidence level: 1.

Technical efficacy: Stage 2.