Journal of Magnetic Resonance Imaging最新文献

Background: Cystic fibrosis (CF) monitoring relies on computed tomography (CT), but ultra-short echo time MRI (UTE-MRI) offers a radiation-free alternative. However, its clinical adoption is hindered by the laborious and subjective manual analysis, which prevents standardized quantification of bronchial abnormalities.

Purpose: To develop a deep learning (DL) system for the segmentation of CF bronchial abnormalities on UTE-MRI and assess clinical relevance in patients undergoing cystic fibrosis transmembrane conductance regulator (CFTR) modulator treatment.

Study type: Retrospective.

Population: One-hundred and sixty-six CF patients were included (age = 23 ± 11, 48% male), comprising a training set (n = 97), a test set (n = 25), and an independent clinical validation cohort (n = 44).

Field strength/sequence: 1.5T/UTE-MRI 3D gradient-echo Spiral Volume Interpolated Breath-hold Examination (VIBE) sequence.

Assessment: The RiSeNet architecture was trained using paired UTE-MRI and CT scans. Its technical performance was evaluated against expert-refined segmentations and compared to state-of-the-art segmentation models using topology-aware metrics: Normalized Surface Dice (NSD) and CenterLine Dice (clDice). Clinical validation was performed by correlating automated measurements at baseline (M0) and 1-year post-CFTR modulator treatment (M12) with Bhalla scores and pulmonary function tests (FEV1%p).

Statistical tests: Student's t-test, Mann-Whitney, Wilcoxon, and Chi-square tests were used for group comparisons. The Spearman test was used to assess correlations. A p value < 0.05 was considered statistically significant.

Results: In the test group, RiSeNet achieved significantly superior performance versus state-of-the-art with NSD scores of 0.84 for bronchiectasis, 0.90 for wall thickening, and 0.75 for mucus; and clDice scores of 0.69, 0.61, and 0.64, respectively. In the clinical validation group, significant correlations with Bhalla (ρ = -0.92/-0.85) and FEV1%p (ρ = -0.68/-0.67) were observed pre/post-CFTR modulator. Post-CFTR modulator, FEV1%p improved (69%-92%) with significant reductions in bronchiectasis (3.88-1.25), wall thickening (30.43-3.05), and mucus (53.30-11.80).

Data conclusion: RiSeNet may enable semantic segmentation of CF abnormalities on radiation-free UTE-MRI.

Evidence level: 3 TECHNICAL EFFICACY: 4.

Background: Gadopiclenol is a high-relaxivity contrast agent enabling dose reduction while maintaining image quality. However, comparison with conventional agents remains limited in body MRI.

Purpose: To intra-individually compare half-dose gadopiclenol and standard-dose gadobenate for image quality and lesion conspicuity in abdominal MRI.

Study type: Retrospective.

Population: One hundred patients (55 men; mean age: 64 ± 14 years) who underwent both abdominal MRI with gadobenate (0.1 mmol/kg) and gadopiclenol (0.05 mmol/kg) on the same scanner within 12 months.

Field strength/sequence: 1.5T/3T, dynamic T1-weighted imaging pre-contrast, early arterial (EAP), late arterial (LAP), portal venous (PVP), and equilibrium phases (EP) using 3D fat-suppressed gradient echo sequence.

Assessment: Signal intensity of liver, pancreas, spleen, kidneys, aorta, portal vein, and abdominal lesions was measured on each phase except EAP. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and magnitude of contrast enhancement (ΔE) were calculated for organs. In lesions, lesion-to-background ratio (LBR) and ΔE were calculated. Subjective image quality and lesion conspicuity were assessed by three readers using a 5-point Likert scale.

Statistical tests: Paired t-test and Wilcoxon test. p < 0.05 indicated statistically significant results.

Results: Gadopiclenol yielded significantly higher CNR and SNR for pancreas, portal vein, and kidney in LAP. No significant differences in CNR (p: 0.372-0.858) and SNR (p: 0.433-0.936) were found in PVP. In EP, gadobenate showed higher hepatic CNR, while CNR and SNR of all other organs were comparable (p: 0.103-0.912). Gadopiclenol showed higher pancreatic ΔE in all enhanced phases. LBR and ΔE of 21 evaluated lesions were comparable across all phases (p: 0.100-0.821). No significant differences were observed in readers' perception of lesion enhancement (p: 0.059-0.957).

Conclusion: Half-dose gadopiclenol provides comparable subjective image quality and lesion conspicuity to standard-dose gadobenate, with superior pancreatic, kidney, and portal vein enhancement in LAP, and similar performance in PVP and EP.

Level of evidence: 4:

Background: The electrocardiogram (ECG) used for gating in cardiac MRI may be compromised by multiple confounders inside the scanner bore.

Purpose: To quantify the influence of magnetic field strengths (1.5 T/3 T/7 T), standardized electrode positions, and imaging sequences on ECG signals used for gating.

Study type: Prospective.

Population: Sixteen healthy volunteers (eight male; mean age 26.25 ± 7.67 years).

Field strength/sequence: Balanced steady-state free precession cine (1.5 T/3 T), fast low-angle shot cine (7 T), and 4D flow (1.5 T/3 T/7 T) sequences.

Assessment: ECG-signals were recorded during breath-hold and non-breath-hold short axis cine (sax-bh and sax-nbh, respectively) and 4D flow scans at 1.5 T/3 T/7 T. All scans were repeated with 4 standardized electrode positionings (pos1-4) at each field strength. Pos1/2 were vendor-recommended positionings for 1.5 T/3 T/7 T scans, respectively, whereas pos3/4 were alternative positionings recommended in previous studies. Similarity between confounded ECG-signals and unconfounded baseline ECG-signals was assessed by QRS-feature correlation. Cine image quality (IQ) was assessed by 3 readers (with 6, 10, and 22 years experience) on a four-point Likert scale.

Statistical tests: Linear mixed models with type III tests of fixed effects (overall) and t tests with adjusted degrees of freedom (pairwise subgroup-comparisons) at significance level p < 0.05.

Results: Increasing field strength resulted in significantly decreasing similarity to baseline measurements, with r values (provided with 95% confidence interval) of 1.5 T: 97% (92.6-101.3); 3 T: 91.4% (87.1-95.8); 7 T: 50.4% (46-54.9) and lower IQ: 1.5 T: 2.33 (2.12-2.55); 3 T: 1.96 (1.75-2.17); 7 T: 0.91 (0.7-1.12). Vendor-specified electrode positions pos1: 91.8% (87.2-96.5), pos2: 88.3% (83.7-92.9) showed significantly higher correlation with baseline measurements than alternative positions pos3: 67.5% (62.9-72.1) and pos4: 70.8% (66.2-75.4). The evaluated standardized sequences showed similar amounts of electrocardiogram distortion, with r values of: sax-bh: 77.3% (73-81.7); 4D: 79.3% (75-83.7), p = 0.54; sax-nbh: 82.1% (77.8-86.5), p = 0.31, but the difference between sax-bh and sax-nbh: 4.8% (2.88-6.72) was significant.

Data conclusion: Increasing field strength leads to significant ECG signal distortions. Vendor-specified positions 1/2 resulted in less distorted ECG signals than alternative positions 3/4 recommended in previous publications.

Level of evidence: 2:

Technical efficacy: Stage 5.

Background: 2D multi-slice MRI techniques for evaluating regional ventilation in neonatal lung diseases, including bronchopulmonary dysplasia (BPD), have limited through-plane resolution, potentially missing heterogeneous lung abnormalities. 3D ultra-short echo time (UTE) MRI phase-resolved functional lung (PREFUL) improves spatial resolution but has not been used to evaluate infants with BPD.

Purpose: To demonstrate the feasibility of 3D UTE MRI for structural and functional assessment in infants with BPD.

Study type: Retrospective.

Population: A total of 28 infants with BPD (female: male = 8:20; 14 required invasive ventilation at MRI, 14 required non-invasive ventilation).

Field strength/sequence: Free-breathing, respiratory bellows-gated (acquired 1.19-1.25 mm³ isotropic) 3D gradient echo UTE MRI on a 1.5 T scanner.

Assessment: Images were retrospectively reconstructed into 24 respiratory phases with motion-resolved reconstruction using compressed sensing. Regional ventilation (RVent), flow-volume loop cross correlation metric (FVL-CM), and corresponding ventilation defect maps (VDP_RVent, VDP_FVL-CM, and the combination, VDP_combined) were derived using the 3D PREFUL method. Structural lung abnormalities were assessed by two readers using a modified Ochiai scoring system, and parenchyma was defined as normal intensity, hypointense, or hyperintense.

Statistical tests: The Mann-Whitney U Test, Spearman's correlation, and the Kruskal-Wallis test with Dunn's multiple-comparisons tests were used. Statistical significance was defined as p < 0.05.

Results: In the mechanically ventilated infants VDP_FVL-CM (median [IQR] = 45.8 [28.5-55.9]%) and VDP_combined (57.2% [35.2-69.3]%) were significantly higher as compared to non-ventilated patients (VDP_FVL-CM = 22.8% [17.2-34.7]% and VDP_combined = 30.7 [25.1-43.9]%). All PREFUL MRI VDP measures significantly correlated with total lung score (all ρ ≥ 0.45). RVent was significantly lower in hyperintense regions (0.06 [0.04-0.08] mL/mL) compared to normal intensity regions (0.09 [0.07-0.13] mL/mL), whereas FVL-CM was significantly decreased in hypointense regions (79 [66-87]%) compared to normal (92 [90-95]%) and hyperintense regions (91 [81-96]%).

Data conclusion: UTE MRI is feasible for assessing regional functional lung abnormalities in infants with BPD that directly correlate with reader-based assessments of parenchymal disease severity.

Evidence level: 4.

Technical efficacy: Stage 1.

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: Primary sclerosing cholangitis (PSC) is a chronic autoimmune disease involving inflammation in the liver and biliary system, manifesting as biliary strictures and cholestasis, and leading to hepatic fibrosis. Due to variable patterns of fibrosis, precise criteria for risk stratification of these patients have yet to be determined. Elasticity-based methods are widely used to estimate the stage of liver fibrosis in PSC.

Purpose: To review the role of different modalities of quantitative elastography in relation to the clinical and fibrosis biomarkers of PSC for the diagnosis and prognosis of this disease.

Study type: SYSTEMATIC REVIEW: Population or subjects or phantom or specimen or animal model: We conducted a systematic review, adhering to the PRISMA guidelines, and searched PubMed and found 24 articles on the performance of elastography techniques in PSC.

Assessment: We qualitatively evaluated methodological limitations including patient selection, reference standard, elasticity acquisition protocols, and outcome definitions.

Statistical tests: N/A.

Results: Based on our review, magnetic resonance elastography (MRE) performs better than vibration controlled transient elastography (VCTE), point shear-wave elastography (p-SWE), and acoustic radiation force impulse (ARFI) in prediction of poor clinical outcomes in patients with PSC. MRE, an operator-independent technique, estimates liver stiffness by averaging nearly the total liver volume. Compared with ultrasound-based elastography, MRE has a lower technical failure rate in assessment of liver fibrosis. Liver stiffness determined by MRE is also correlated with clinical scores such as Primary Sclerosing Cholangitis Risk Estimate Tool (PREsTo) and Mayo Risk Score (MRS) in patients with PSC.

Data conclusion: Of the elastography methods reviewed, MRE appears to be a preferred modality for staging liver fibrosis and risk stratification of patients with PSC, whereas ultrasound-based techniques like VCTE are more accessible but might be less accurate. Further studies are warranted to assess the diagnostic and prognostic performance of the various elastography techniques in patients with PSC.

Level of evidence: 5:

Technical efficacy stage: 5.

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.