Introduction: Numerous techniques for myelin water imaging (MWI) have been devised to specifically assess alterations in myelin. The biomarker employed to measure changes in myelin content is known as the myelin water fraction (MWF). The short TR adiabatic inversion recovery (STAIR) sequence has recently been identified as a highly effective method for calculating MWF. The purpose of this study is to develop a new clinical transitional myelin water imaging (MWI) technique that combines STAIR preparation and echo-planar imaging (EPI) (STAIR-EPI) sequence for data acquisition. Methods: Myelin water (MW) in the brain has shorter T1 and T2 relaxation times than intracellular and extracellular water. In the proposed STAIR-EPI sequence, a short TR (e.g., ≤300 ms) together with an optimized inversion time enable robust long T1 water suppression with a wide range of T1 values [i.e., (600, 2,000) ms]. The EPI allows fast data acquisition of the remaining MW signals. Seven healthy volunteers and seven patients with multiple sclerosis (MS) were recruited and scanned in this study. The apparent myelin water fraction (aMWF), defined as the signal ratio of MW to total water, was measured in the lesions and normal-appearing white matter (NAWM) in MS patients and compared with those measured in the normal white matter (NWM) in healthy volunteers. Results: As seen in the STAIR-EPI images acquired from MS patients, the MS lesions show lower signal intensities than NAWM do. The aMWF measurements for both MS lesions (3.6 ± 1.3%) and NAWM (8.6 ± 1.2%) in MS patients are significantly lower than NWM (10 ± 1.3%) in healthy volunteers (P < 0.001). Discussion: The proposed STAIR-EPI technique, which can be implemented in MRI scanners from all vendors, is able to detect myelin loss in both MS lesions and NAWM in MS patients.
Elevated serum uric acid (SUA) levels have been associated with an increased risk of cardiovascular (CV) disease and acute ischemic stroke (AIS) as well as many other medical conditions. AIS is a CV complication that is the second most common cause of mortality worldwide. It results from reduced blood flow to the brain by means of thrombosis, embolism, or systemic hypoperfusion. Studies have demonstrated an association between SUA levels and CV events, with a significant dose-response relationship between elevated SUA levels and stroke risk. Since the relationship between SUA levels and AIS risk has been established, studies are also being conducted in order to evaluate whether antihyperuricemic drugs can lower this risk. Allopurinol use in hyperuricemic patients has been shown to decrease the risk of major CV events, which include AIS. This narrative review aims to investigate the role of SUA as an independent risk factor for AIS along with the proposed biological mechanisms by thoroughly appraising research findings from relevant full-text articles and abstracts indexed in PubMed and the Cochrane Library. In this literature, we will be discussing hyperuricemia, AIS, the association between the two, and the use of antihyperuricemic medications on stroke prognosis. This review will also shed new light on studies that have begun to provide insight into the predictive role of hyperuricemia in AIS.
