Saturation-Transfer-Based MRI of the Brain in Multiple Sclerosis Patients at 3T.

Abstract

Background: Multiple sclerosis (MS) is an autoimmune demyelinating disease that attacks myelin. MRI is an important imaging modality for diagnosis and monitoring in MS. However, the current standard MRI protocol for MS lacks sequences capable of detecting molecular changes.

Purpose: To present a saturation-transfer-based MRI protocol, including chemical exchange saturation transfer (CEST) and magnetization transfer indirect spin labeling (MISL) sequences, for quantifying molecular changes and water exchange in the brain of MS patients.

Study type: Prospective.

Population: Fifty-two participants including 31 healthy controls (HC) (18 females and 13 males) and 21 MS patients (18 females and 3 males).

Field strength/sequence: 3D inversion-prepared gradient echo T1w, 3D fast spin echo T2w, 3D CUBE CEST and MISL at 3.0 T.

Assessment: Multiple CEST contrasts between HC and MS groups were analyzed using double-step multi-pool Lorentzian fitting (DMPLF) and Lorentzian difference analysis (LDA) to evaluate and compare their diagnostic performance. MISL signals at -20 and -10 ppm were quantified by the normalized signal reduction in cerebrospinal fluid (CSF). T1w MRI was used to quantify brain volumes.

Statistical tests: Unpaired Student's t-test, receiver operating characteristic (ROC) curve, area under the curve (AUC), and binary logistic regression analysis. p < 0.05 was considered statistically significant.

Results: CEST detected decreased signals in the brain of MS patients using both DMPLF and LDA, with DMPLF demonstrating superior performance in differentiating MS from HC (AUC, 0.93; 95% CI: 0.86, 1.00). MS patients showed significantly lower whole brain MISL signals than HCs at both -20 ppm (0.04 ± 0.01 vs. 0.06 ± 0.02) and -10 ppm (0.06 ± 0.02 vs. 0.08 ± 0.02). MS patients showed a significant decrease (-6.57%) in brain tissue and an increase (+20.73%) in CSF volume ratios compared to HCs.

Data conclusion: The saturation-transfer-based MRI framework can effectively evaluate molecular changes and CSF-tissue water exchange in the brains of MS patients.

Evidence level: 2.

Technical efficacy: Stage 3.