96 research outputs found
Interâ and intraâsoftware reproducibility of computed tomography lung density measurements
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156221/2/mp14130.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156221/1/mp14130_am.pd
Global left ventricular remodeling, extent of inferior wall infarct, and mitral valve geometry are important predictors of mitral regurgitation severity than total infarct size in advanced ischemic cardiomyopathy
Mitral regurgitation (MR) is common in patients with ischemic cardiomyopathy (ICM) and independently associated with worse mortality. We sought to determine the impact of adverse LV remodeling, total myocardial infarct (MI) size, location and extent of regional MI, and mitral valve geometry on the severity of mitral regurgitation
Test-retest repeatability of ADC in prostate using the multi b-Value VERDICT acquisition
Purpose:
VERDICT (Vascular, Extracellular, Restricted Diffusion for Cytometry in Tumours) MRI is a multi b-value, variable diffusion time DWI sequence that allows generation of ADC maps from different b-value and diffusion time combinations. The aim was to assess precision of prostate ADC measurements from varying b-value combinations using VERDICT and determine which protocol provides the most repeatable ADC.
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Materials and Methods:
Forty-one men (median age: 67.7 years) from a prior prospective VERDICT study (April 2016âOctober 2017) were analysed retrospectively. Men who were suspected of prostate cancer and scanned twice using VERDICT were included. ADC maps were formed using 5b-value combinations and the within-subject standard deviations (wSD) were calculated per ADC map. Three anatomical locations were analysed per subject: normal TZ (transition zone), normal PZ (peripheral zone), and index lesions. Repeated measures ANOVAs showed which b-value range had the lowest wSD, Spearman correlation and generalized linear model regression analysis determined whether wSD was related to ADC magnitude and ROI size.
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Results:
The mean lesion ADC for b0 b1500 had the lowest wSD in most zones (0.18â0.58x10-4 mm2/s). The wSD was unaffected by ADC magnitude (Lesion: p = 0.064, TZ: p = 0.368, PZ: p = 0.072) and lesion Likert score (p = 0.95). wSD showed a decrease with ROI size pooled over zones (p = 0.019, adjusted regression coefficient = -1.6x10-3, larger ROIs for TZ versus PZ versus lesions). ADC maps formed with a maximum b-value of 500 s/mm2 had the largest wSDs (1.90â10.24x10-4 mm2/s).
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Conclusion:
ADC maps generated from b0 b1500 have better repeatability in normal TZ, normal PZ, and index lesions
Variability in Surgical Treatment of Spondylolisthesis Among Spine Surgeons
Background
There are a multitude of treatments for low-grade lumbar spondylolisthesis. There are no clear guidelines for the optimal approach.
Objective
To identify the surgical treatment patterns for spondylolisthesis among United States spine surgeons.
Methods
445 spine surgeons in the United States completed a survey of clinical/radiographic case scenarios on patients with lumbar spondylolisthesis with neurogenic claudication with (S+BP) or without (SâBP) associated mechanical back pain. Treatment options included decompression, laminectomy with posterolateral fusion, posterior lumbar interbody fusion, or none of the above. The primary outcome measure was the probability of 2 randomly chosen surgeons disagreeing on the treatment method.
Results
There was 64% disagreement (36% agreement) among surgeons for treatment of spondylolisthesis with mechanical back pain (S+BP) and 71% disagreement (29% agreement) for spondylolisthesis without mechanical back pain (SâBP). For S+BP, disagreement was 52% for those practicing 5 to 10 years versus 70% among those practicing more than 20 years. Orthopedic surgeons had greater disagreement than did neurosurgeons (76% vs. 56%) for S+BP. Greater clinical equipoise was seen for SâBP than for S+BP regardless of surgeon characteristics. For spondylolisthesis without mechanical back pain, neurosurgeons were significantly more likely to select decompression-only than were orthopedic surgeons, who more commonly selected fusion.
Conclusions
Clinical equipoise exists for the treatment of spondylolisthesis. Differences are greater when the patient presents without associated back pain. Surgeon case volume, practice duration, and specialty training influence operative decisions for a given pathologic condition. Recognizing this practice variation will hopefully lead to better evidence and practice guidelines for the optimal and most cost-effective treatment paradigms
Predictors of Mortality Following Mitral Intervention
Background
Ischemic mitral regurgitation is associated with substantial risk of death. Although surgical mitral valve intervention (MVi) may improve symptoms, it has not been shown to improve survival. The aim of this study was to identify predictors of mortality in patients with ischemic mitral regurgitation and MVi.
Methods and Results
We evaluated 117 consecutive patients (age, 65±10 years) with advanced ischemic cardiomyopathy who underwent cardiac magnetic resonance and subsequent MVi between January 1, 2002 and January 1, 2012. Cardiac magnetic resonance was used to assess left ventricular remodeling and myocardial scarring. The effective regurgitant orifice area was calculated from the proximal isovelocity surface area by echocardiography. There were 43 deaths (37%) during followâup (median, 62 months). On multivariable analysis, age â„70 years (P=0.013), diabetes mellitus (P=0.001), dyslipidemia (P=0.012), papillary muscle scar (P=0.010), incomplete revascularization (P=0.001), and total scar %Ăeffective regurgitant orifice area â„0.20 cm2 (P=0.005) were each independently associated with allâcause mortality. Although patients with effective regurgitant orifice area <0.2 cm2 at baseline demonstrated an increased hazard ratio of 3.3 for every 10% increase in scar, the hazard ratio increased to 9 for every 10% increase in scar in those with baseline effective regurgitant orifice area â„0.20 cm2. Mortality also was significantly higher in patients with incomplete revascularization compared with those with vascularized viable myocardium (61% versus 28%; P<0.001).
Conclusions
Increased total scar burden and the presence of incomplete revascularization are powerful predictors of mortality in patients with advanced ischemic cardiomyopathy undergoing MVi. Viability assessment with cardiac magnetic resonance imaging can identify which patients with ischemic mitral regurgitation are at highest risk for mortality after surgical MVi
The RSNA QIBA Profile for Amyloid PET as an Imaging Biomarker for Cerebral Amyloid Quantification
A standardized approach to acquiring amyloid PET images increases their value as disease and drug response biomarkers. Most 18F PET amyloid brain scans often are assessed only visually (per regulatory labels), with a binary decision indicating the presence or absence of Alzheimer disease amyloid pathology. Minimizing technical variance allows precise, quantitative SUV ratios (SUVRs) for early detection of b-amyloid plaques and allows the effectiveness of antiamyloid treatments to be assessed with serial studies. Methods: The Quantitative Imaging Biomarkers Alliance amyloid PET biomarker committee developed and validated a profile to characterize and reduce the variability of SUVRs, increasing statistical power for these assessments. Results: On achieving conformance, sites can justify a claim that brain amyloid burden reflected by the SUVR is measurable to a within-subject coefficient of variation of no more than 1.94% when the same radiopharmaceutical, scanner, acquisition, and analysis protocols are used. Conclusion: This overview explains the claim, requirements, barriers, and potential future developments of the profile to achieve precision in clinical and research amyloid PET imaging.</p
STARD 2015: An Updated List of Essential Items for Reporting Diagnostic Accuracy Studies.
Incomplete reporting has been identified as a major source of avoidable waste in biomedical research. Essential information is often not provided in study reports, impeding the identification, critical appraisal, and replication of studies. To improve the quality of reporting of diagnostic accuracy studies, the Standards for Reporting of Diagnostic Accuracy Studies (STARD) statement was developed. Here we present STARD 2015, an updated list of 30 essential items that should be included in every report of a diagnostic accuracy study. This update incorporates recent evidence about sources of bias and variability in diagnostic accuracy and is intended to facilitate the use of STARD. As such, STARD 2015 may help to improve completeness and transparency in reporting of diagnostic accuracy studies
Determining sample size for roc studies: what is reasonable for the expected difference in testsâ ROC areas?
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