Journal of Magnetic Resonance Imaging最新文献

Magnetic resonance imaging (MRI) is routinely used in the musculoskeletal system to measure skeletal muscle structure and pathology in health and disease. Recently, it has been shown that MRI also has promise for detecting the functional changes, which occur in muscles, commonly associated with a range of neuromuscular disorders. This review focuses on novel adaptations of MRI, which can detect the activity of the functional sub-units of skeletal muscle, the motor units, referred to as "motor unit MRI (MUMRI)." MUMRI utilizes pulsed gradient spin echo, pulsed gradient stimulated echo and phase contrast MRI sequences and has, so far, been used to investigate spontaneous motor unit activity (fasciculation) and used in combination with electrical nerve stimulation to study motor unit morphology and muscle twitch dynamics. Through detection of disease driven changes in motor unit activity, MUMRI shows promise as a tool to aid in both earlier diagnosis of neuromuscular disorders and to help in furthering our understanding of the underlying mechanisms, which proceed gross structural and anatomical changes within diseased muscle. Here, we summarize evidence for the use of MUMRI in neuromuscular disorders and discuss what future research is required to translate MUMRI toward clinical practice. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 3.

Background: Patients with restrictive cardiomyopathy (RCM) have impaired diastolic filling and hemodynamic congestion. Pulmonary transit time (PTT) and pulmonary blood volume index (PBVi) reflect the hemodynamic status, but the relationship with left ventricle (LV) dysfunction remains unclear.

Purpose: To evaluate the PTT and PBVi in RCM patients, the association with diastolic dysfunction and LV deformation, and the effects on the occurrence of major adverse cardiac events (MACE) in RCM patients.

Study type: Retrospective.

Population: 137 RCM patients (88 men, age 58.80 ± 10.83 years) and 68 age- and sex-matched controls (46 men, age 57.00 ± 8.59 years).

Field strength/sequence: 3.0T/Balanced steady-state free precession sequence, recovery prepared echo-planar imaging sequence, and phase-sensitive inversion recovery sequence.

Assessment: The LV function and peak strain (PS) parameters were measured. The PTT was calculated and corrected by heart rate (PTTc). The PBVi was calculated as the product of PTTc and RV stroke volume index.

Statistical tests: Chi-squared test, student's t-test, Mann-Whitney U test, Pearson's or Spearman's correlation, multivariate linear regression, Kaplan-Meier survival analysis, and Cox regression models analysis. A P-value <0.05 was considered statistically significant.

Results: The PTTc showed a significant correlation with the E/A ratio (r = 0.282), and PBVi showed a significant correlation with the E/e' ratio, E/A ratio, and diastolic dysfunction stage (r = 0.222, 0.320, and 0.270). PTTc showed an independent association with LVEF, LV circumferential PS, and LV longitudinal PS (β = 0.472, 0.299, and 0.328). In Kaplan-Meier analysis, higher PTTc and PBVi were significantly associated with MACE. In multivariable Cox regression analysis, PTTc was a significantly independent predictor of the MACE in combination with both cardiac MRI functional and tissue parameters (hazard ratio: 1.23/1.32, 95% confidence interval: 1.10-1.42/1.20-1.46).

Data conclusion: PTTc and PBVi are associated with diastolic dysfunction and deteriorated LV deformation, and PTTc independently predicts MACE in patients with RCM.

Level of evidence: 3 TECHNICAL EFFICACY: Stage 2.

Background: The National Institutes of Health Stroke Scale (NIHSS) and the modified Rankin scale (mRS) scores have important shortcomings. Amide proton transfer-weighted (APTw) imaging might offer more valuable information in ischemic strokes assessment.

Purpose: To utilize APTw, apparent diffusion coefficient (ADC), and computed tomography perfusion (CTP) for the assessment of clinical symptom severity and 90-day prognosis in patients diagnosed with ischemic stroke.

Study type: Prospective.

Subjects: 61 patients (mean age 63.2 ± 9.7 years; 46 males, 15 females) with ischemic strokes were included in the study.

Field strength/sequence: 3T/turbo spin echo (TSE) T₁-weighted imaging, T₂-weighted imaging, T₂-fluid attenuated inversion recovery (T₂-FLAIR), diffusion-weighted imaging (DWI), and single-shot TSE APTw imaging.

Assessment: APTw, ADC, and CTP were used to compare patient subgroups and construct a prognostic nomogram model.

Statistical tests: Kolmogorov-Smirnov test, t-test, Mann-Whitney U test, chi-square test, Pearson correlation analysis, multivariate logistic regression analysis, decision curve analysis (DCA), receiver operating characteristic curves (ROCs). The significance threshold was set at P < 0.05.

Results: Correlation analysis revealed that APTw and NIHSS exhibit the highest correlation (r = -0.634, 95% confidence interval [CI] -0.418 to -0.782), surpassing that of ADC and lesion size. Multivariable analysis revealed APTw (odds ratio [OR] 0.905, 95% CI 0.845-0.970), ADC (OR 0.745, 95% CI 0.609-0.911), and infarct core-cerebral blood volume (IC-CBV) (OR 0.547, 95% CI 0.310-0.964) as potential risk factors associated with a poor prognosis. The nomogram model demonstrated the highest predictive efficacy, with an area under the curve (AUC) of 0.960 (95% CI 0.911-0.988), exceeding that of APTw, ADC, and IC-CBV individually.

Data conclusion: The APTw technique holds potential value in categorizing and managing patients with ischemic stroke, offering guidance for the implementation of clinical treatment strategies.

Level of evidence: 1 TECHNICAL EFFICACY: Stage 2.

Background: Non-invasive evaluation of phosphomonoesters (PMEs) and phosphodiesters (PDEs) by 31-phosphorus MR spectroscopy (³¹P MRS) may have potential for early therapy (non-)response assessment in cancer. However, ³¹P MRS has not yet been applied to investigate the human pancreas in vivo.

Purpose: To assess the technical feasibility and repeatability of ³¹P MR spectroscopic imaging (MRSI) of the pancreas, compare ³¹P metabolite levels between pancreas and liver, and determine the feasibility of ³¹P MRSI in pancreatic cancer.

Study type: Prospective cohort study.

Population: 10 healthy subjects (age 34 ± 12 years, four females) and one patient (73-year-old female) with pancreatic ductal adenocarcinoma.

Field strength/sequence: 7-T, ³¹P FID-MRSI, ¹H gradient-echo MRI.

Assessment: ³¹P FID-MRSI of the abdomen (including the pancreas and liver) was performed with a nominal voxel size of 20 mm (isotropic). For repeatability measurements, healthy subjects were scanned twice on the same day. The patient was only scanned once. Test-retest ³¹P MRSI data of pancreas and liver voxels (segmented on ¹H MRI) of healthy subjects were quantified by fitting in the time domain and signal amplitudes were normalized to γ-adenosine triphosphate. In addition, the PME/PDE ratio was calculated. Metabolite levels were averaged over all voxels within the pancreas, right liver lobe and left liver lobe, respectively.

Statistical tests: Repeatability of test-retest data from healthy pancreas was assessed by paired t-tests, Bland-Altman analyses, and calculation of the intrasubject coefficients of variation (CoVs). Significant differences between healthy pancreas and right and left liver lobes were assessed with a two-way analysis of variance (ANOVA) for repeated measures. A P-value <0.05 was considered statistically significant.

Results: The intrasubject CoVs for PME, PDE, and PME/PDE in healthy pancreas were below 20%. Furthermore, PME and PME/PDE were significantly higher in pancreas compared to liver. In the patient with pancreatic cancer, qualitatively, elevated relative PME signals were observed in comparison with healthy pancreas.

Data conclusion: In vivo ³¹P MRSI of the human healthy pancreas and in pancreatic cancer may be feasible at 7 T.

Evidence level: 3 TECHNICAL EFFICACY: Stage 2.

Background: Liver fibrosis (LF) precipitates systemic hemodynamic alterations, however, its impact on the aorta remaining undefined.

Purpose: To assess aorta hemodynamics changes during LF development in a rabbit model.

Study type: Prospective, experimental.

Animal model: Thirty 7-month-old male rabbits underwent bile duct ligation (BDL) to induce LF.

Field strength/sequence: Biweekly four-dimensional (4D) flow imaging incorporating a 3D gradient-echo at 3.0 T scanner for 14 weeks post-BDL.

Assessment: Histopathological exams for 2-5 rabbits were performed at each time point, following each MRI scan. LF was graded using the Metavir scale by a pathologist. 4D flow was analyzed by two radiologists using dedicated postprocessing software. They recorded 4D flow parameters at four aorta sections (aortic sinus, before and after bifurcation of aortic arch, and descending aorta).

Statistical tests: The linear mixed model; Bonferroni correction; Pearson correlation coefficient (r); receiver operating characteristic (ROC) curve; Delong test. The level of significance was set at P < 0.05.

Results: Following BDL, the wall shear stress (WSS) (0.23-0.32 Pa), energy loss (EL) (0.27-1.55 mW) of aorta significantly increased at the second week for each plane, peaking at the sixth week (WSS: 0.35-0.49 Pa, EL: 0.57-2.0 mW). So did the relative pressure difference (RPD) (second week: 1.67 ± 1.63 mmHg, sixth week: 2.43 ± 0.63 mmHg) in plane 2. Notably, the RPD in plane 2 at the second week displayed the highest area under ROC curve of 0.998 (specificity: 1, sensitivity: 0.967). LF were found at the second, fourth, and sixth week after BDL, with grade F2, F3, and F4, respectively. The RPD in plane 2 was most strongly correlated with the severity of LF (r = 0.86).

Data conclusions: The occurrence of LF could increase WSS, EL, and RPD of aorta as early as the second week following BDL.

Level of evidence: 1 TECHNICAL EFFICACY: Stage 2.

Background: Movement disorders such as Parkinson's disease are associated with structural and functional changes in specific brain regions. Advanced magnetic resonance imaging (MRI) techniques combined with machine learning (ML) are promising tools for identifying imaging biomarkers and patterns associated with these disorders.

Purpose/hypothesis: We aimed to systematically identify the brain regions most commonly affected in movement disorders using ML approaches applied to structural and functional MRI data. We searched the PubMed and Scopus databases using relevant keywords up to June 2023 for studies that used ML approaches to detect brain regions associated with movement disorders using MRI data.

Study type: A systematic review and diagnostic meta-analysis.

Population/subjects: Sixty-seven studies with 6,285 patients were included.

Field strength/sequence: Studies utilizing 1.5T or 3T MR scanners and the acquisition of diffusion tensor imaging (DTI), structural MRI (sMRI), functional MRI (fMRI), or a combination of these were included.

Assessment: The authors independently assessed the study quality using the CLAIM and QUADAS-2 criteria and extracted data on diagnostic accuracy measures.

Statistical tests: Sensitivity, specificity, accuracy, and area under the curve were pooled using random-effects models. Q statistics and the I² index were used to evaluate heterogeneity, and Begg's funnel plot was used to identify publication bias.

Results: sMRI showed the highest sensitivity (93%) and mixed modalities had the highest specificity (90%) for detecting regional abnormalities. sMRI had a 94% sensitivity for identifying subcortical changes. The support vector machine (93%) and logistic regression (91%) models exhibited high diagnostic accuracies.

Data conclusion: The combination of advanced MR neuroimaging techniques and ML is a promising approach for identifying brain biomarkers and affected regions in movement disorders with subcortical structures frequently implicated. Structural MRI, in particular, showed strong performance.

Level of evidence: 1 TECHNICAL EFFICACY: Stage 2.

Background: It remains unclear whether extracting peritumoral volume (PTV) radiomics features are useful tools for evaluating response to chemotherapy of epithelial ovarian cancer (EOC).

Purpose: To evaluate MRI radiomics signatures (RS) capturing subtle changes of PTV and their added evaluation performance to whole tumor volume (WTV) for response to chemotherapy in patients with EOC.

Study type: Retrospective.

Population: 219 patients aged from 15 to 79 years were enrolled.

Field strength/sequence: 3.0 or 1.5T, axial fat-suppressed T2-weighted imaging (FS-T2WI), diffusion-weighted imaging (DWI), and contrast enhanced T1-weighted imaging (CE-T1WI).

Assessment: MRI features were extracted from the four axial sequences and six different volumes of interest (VOIs) (WTV and WTV + PTV (WPTV)) with different peritumor sizes (PS) ranging from 1 to 5 mm. Those features underwent preprocessing, and the most informative features were selected using minimum redundancy maximum relevance and least absolute shrinkage and selection operator to construct the RS. The optimal RS, with the highest area under the curve (AUC) of receiver operating characteristic was then integrated with independent clinical characteristics through multivariable logistic regression to construct the radiomics-clinical model (RCM).

Statistical tests: Mann-Whitney U test, chi-squared test, DeLong test, log-rank test. P < 0.05 indicated a significant difference.

Results: All the RSs constructed on WPTV exhibited higher AUCs (0.720-0.756) than WTV (0.671). Of which, RS with PS = 2 mm displayed a significantly better performance (AUC = 0.756). International Federation of Gynecology and Obstetrics (FIGO) stage was identified as the exclusive independent clinical evaluation characteristic, and the RCM demonstrated higher AUC (0.790) than the RS, but without statistical significance (P = 0.261).

Data conclusion: The radiomics features extracted from PTV could increase the efficiency of WTV radiomics for evaluating the chemotherapy response of EOC. The cut-off of 2 mm PTV was a reasonable value to obtain effective evaluation efficiency.

Level of evidence: 4 TECHNICAL EFFICACY: Stage 2.