Hyperoxia-induced ΔR1: MRI biomarker of irreversible ischemic damage in acute stroke

Purpose: Accurate and reliable measurement of irreversibly damaged area is an important diagnostic task in acute stroke, particularly for helping development of neuroprotective treatment. This study was performed to validate hyperoxia-induced ΔR1 (hyperO2ΔR1) as a useful imaging biomarker for identifying irreversible ischemic damage in stroke. Materials and Methods: In cross-sectional experiment (12 rats, transient occlusion of middle-cerebral artery), hyperO2ΔR1, apparent diffusion coefficient (ADC), 18F-fluorodeoxyglucose uptake on positron emission tomography, cerebral blood flow and cerebral blood volumes were measured 2.5, 4.5, and 6.5 hours after stroke initiation. They were compared among infarct area, non-infarct ischemia and non-ischemic area on the criteria of histology and ADC. The levels of hyperO2ΔR1 and ADC were voxel-wisely measured from the infarct core to the non-ischemic area. In longitudinal experiment (n=9), time-dependent changes of hyperO2ΔR1 and ADC were analyzed at 3, 6, and 24 hours after initiation of transient stroke. Results: In cross sectional study, hyperO2ΔR1 increased exclusively in infarct area at all time points. In contrast, ADC gradually decreased from non-ischemic to infarct areas, and the other parameters did not show consistent patterns. HyperO2ΔR1 showed a sharp decline from the core to the border of infarct areas and a plateaued level in non-infarct areas. Most voxels in infarct area showed hyperO2ΔR1 > 0.04 s-1. There was no noticeable difference of ADC at the border between infarct and non-infarct areas. In longitudinal study, hyperO2ΔR1 was not reverted to normal level once having gone higher than 0.04 s-1, and the area with hyperO2ΔR1 higher than 0.04 s-1 continuously increased over time. ADC in infarct area showed inconsistent temporal changes in each rat. Conclusion: HyperO2ΔR1 can be used as an accurate and reliable biomarker for identifying irreversible ischemic damage in stroke.Docto

Performance of Prostate Imaging Reporting and Data System Version 2.1 for Diagnosis of Prostate Cancer: A Systematic Review and Meta-Analysis

Background The Prostate Imaging Reporting and Data System (PI-RADS) was introduced in 2012 and updated to version 2.1 (v2.1) in early 2019 to improve diagnostic performance and interreader reliability. Purpose To evaluate the diagnostic performance of PI-RADS v2.1 in comparison with v2. Methods A systematic review and meta-analysis of the literature was performed using MEDLINE, EMBASE, and Cochrane databases to identify studies evaluating the diagnostic performance of PI-RADS v2.1 for diagnosing clinically significant prostate cancer (csPCa). Study Type Systematic review and meta-analysis. Subject One thousand two hundred forty-eight patients with 1406 lesions from 10 eligible articles. Field Strength/sequence Conventional MR sequences at 1.5 T and 3 T. Assessment Two reviewers independently identified and reviewed the original articles reporting diagnostic performance of PI-RADS v2.1. Statistical Tests Meta-analytic summary sensitivity and specificity were calculated using a bivariate random effects model. Meta-analytic sensitivity and specificity between PI-RADS v2 and v2.1 were compared. Results The pooled sensitivity and specificity of PI-RADS v2.1 were 87% (95% confidence intervals, 82-91%) and 74% (63-82%), respectively. In five studies available for a head-to-head comparison between PI-RADS v2.1 and v2, there were no significant differences in either sensitivity (90% [86-94%] vs. 88% [83-93%], respectively) or specificity (76% [59-93%] vs. 61% [39-83%], respectively; P = 0.37). The sensitivity and specificity were 81% (73-87%) and 82% (68-91%), respectively, for a PI-RADS score cutoff of >= 4, and 94% (88-97%) and 56% (35-97%) for >= 3. Regarding the zonal location, the sensitivity and specificity for the transitional zone only were 90% (84-96%) and 76% (62-90%) respectively, whereas for the whole gland they were 85% (79-91%) and 71% (57-85%). Data Conclusion PI-RADS v2.1 demonstrated good overall performance for the diagnosis of csPCa. PI-RADS v2.1 tended to show higher specificity than v2, but the difference lacked statistical significance. Level of Evidence 3 Technical Efficacy Stage