Comparative evaluation of brain perfusion with ASL and DSC MRI following intracranial vascular flow diverter stent replacement.

PURPOSE: The objective of this study was to asses brain perfusion parameters and ischemic changes following treatment of aneurysm with flow diverters with two different perfusion MRI technique (Arterial spin labeling and DSC MRI), and to compare the results and effectiveness of these two methods. METHODS: The prospective data was collected from patients with aneurysm who treated with flow diverters. MR examinations, including diffusion-weighted imaging (DWI), ASL, and DSC perfusion MRI, were conducted before and after treatment within the first week and at 6 months. Perfusion parameters of territory area and contralateral side were measured and analyzed by statistically. The relationships between ASL and DSC parameters were analyzed by using Sperman's correlation analysis. RESULTS: A total of 14 cases of aneurysms in 11 patients treated successfully with endovascular flow diverter stent placement. Pretreatment and post treatment (within first week and 6 months) MRI images were evaluated. Asymptomatic randomly distributed millimetric restricted diffusion foci were observed in 8 of all patients. There was no statistically difference between pre and post treatment perfusion parameters (p > 0.05). A statistically significant correlation was found between variable ASL CBF, and the variables of DSC CBF and TTP. CONCLUSIONS: Notwithstanding the fact that flow diverters change flow dynamics in aneurysm sac, there is no any perfusion abnormality in the territory area. Asymptomatic randomly distributed diffusion restricted foci in the both cerebral hemisphere can be observed. ASL and DSC MRI are effective for evaluation of brain perfusion.

DWI-based MR thermometry: could it discriminate Alzheimer's disease from mild cognitive impairment and healthy subjects?

PURPOSE: The aim of this study is to compare lateral ventricular cerebrospinal fluid (CSF) temperature of the patients with Alzheimer's disease (AD), mild cognitive impairment (MCI), and healthy subjects (HS) using diffusion-weighted imaging (DWI)-based magnetic resonance (MR) thermometry. METHODS: Seventy-two patients (37 AD, 19 MCI, 16 HS) who underwent 3-T MR examination from September 2018 to August 2019 were included in this study. Smoking habits, education level, disease duration, and comorbidity status were recorded. Patients were assessed using Mini-Mental State Examination (MMSE) and the Clinical Dementia Rating (CDR) score. Brain temperatures were measured using DWI-based MR thermometry. Group comparisons of brain temperature were performed using the Pearson chi-square, Mann-Whitney, and Kruskal-Wallis tests. Further analysis was performed using the post hoc Bonferroni test. Receiver operating characteristic (ROC) analysis was also used. RESULTS: A CDR score of 0.5, 1, and 2 was 2 (5.4%), 14 (37.8%), and 21 (56.8%) in AD, respectively. The median MMSE score had significant differences among groups and also in pairwise comparisons. The median CSF temperature (°C) values showed statistically significant difference among groups (HS: 38.5 °C, MCI: 38.17 °C, AD: 38.0 °C). The post hoc Mann-Whitney U test indicated a significant difference between AD patients and HS (p = 0.009). There were no significant CSF temperature differences in other pairwise comparisons. CONCLUSION: Lower CSF temperatures were observed in AD patients than in HS, probably due to decreased brain metabolism in AD. DWI-based MR thermometry as a noninvasive imaging method enabling the measurement of CSF temperatures may contribute to the diagnosis of AD.