Objectives: Web-based learning has several potential advantages over lectures, such as anytime-anywhere access, rich multimedia, and nonlinear navigation. While known to be an effective method for learning facts, few studies have examined the effectiveness of Web-based formats for learning procedural skills. The authors sought to determine whether a Web-based tutorial is at least as effective as a didactic lecture for learning ultrasound-guided vascular access (UGVA).Methods: Participating staff emergency physicians (EPs) and junior emergency medicine (EM) residents with no UGVA experience completed a precourse test and were randomized to either a Web-based or a didactic group. The Web-based group was instructed to use an online tutorial and the didactic group attended a lecture. Participants then practiced on simulators and live models without any further instruction. Following a rest period, participants completed a four-station objective structured clinical examination (OSCE), a written examination, and a postcourse questionnaire. Examination results were compared using a noninferiority data analysis with a 10% margin of difference.Results: Twenty-one residents and EPs participated in the study. There were no significant differences in mean OSCE scores (absolute difference = )2.8%; 95% confidence interval [CI] = )9.3% to 3.8%) or written test scores (absolute difference = )1.4%; 95% CI = )7.8% to 5.0%) between the Web group and the didactic group. Both groups demonstrated similar improvements in written test scores (26.1% vs. 25.8%; p = 0.95). Ninety-one percent (10 ⁄ 11) of the Web group and 80% (8 ⁄ 10) of the didactic group participants found the teaching format to be effective (p = 0.59).Conclusions: Our Web-based tutorial was at least as effective as a traditional didactic lecture for teaching the knowledge and skills essential for UGVA. Participants expressed high satisfaction with this teaching technology. Web-based teaching may be a useful alternative to didactic teaching for learning procedural skills.ACADEMIC EMERGENCY MEDICINE 2008; 15:949-954 ª
Image quality metrics (IQMs) such as root mean square error (RMSE) and structural similarity index (SSIM) are commonly used in the evaluation and optimization of accelerated magnetic resonance imaging (MRI) acquisition and reconstruction strategies. However, it is unknown how well these indices relate to a radiologist's perception of diagnostic image quality. In this study, we compare the image quality scores of five radiologists with the RMSE, SSIM, and other potentially useful IQMs: peak signal to noise ratio (PSNR) multi-scale SSIM (MSSSIM), information-weighted SSIM (IWSSIM), gradient magnitude similarity deviation (GMSD), feature similarity index (FSIM), high dynamic range visible difference predictor (HDRVDP), noise quality metric (NQM), and visual information fidelity (VIF). The comparison uses a database of MR images of the brain and abdomen that have been retrospectively degraded by noise, blurring, undersampling, motion, and wavelet compression for a total of 414 degraded images. A total of 1017 subjective scores were assigned by five radiologists. IQM performance was measured via the Spearman rank order correlation coefficient (SROCC) and statistically significant differences in the residuals of the IQM scores and radiologists' scores were tested. When considering SROCC calculated from combining scores from all radiologists across all image types, RMSE and SSIM had lower SROCC than six of the other IQMs included in the study (VIF, FSIM, NQM, GMSD, IWSSIM, and HDRVDP).In no case did SSIM have a higher SROCC or significantly smaller residuals than RMSE. These results should be considered when choosing an IQM in future imaging studies.
Background and Purpose— Variability in computed tomography angiography (CTA) acquisitions may be one explanation for the modest accuracy of the spot sign for predicting intracerebral hemorrhage expansion detected in the multicenter Predicting Hematoma Growth and Outcome in Intracerebral Hemorrhage Using Contrast Bolus CT (PREDICT) study. This study aimed to determine the frequency of the spot sign in intracerebral hemorrhage and its relationship with hematoma expansion depending on the phase of image acquisition. Methods— PREDICT study was a prospective observational cohort study of patients with intracerebral hemorrhage presenting within 6 hours from onset. A post hoc analysis of the Hounsfield units of an artery and venous structure were measured on CTA source images of the entire PREDICT cohort in a core laboratory. Each CTA study was classified into arterial or venous phase and into 1 of 5 specific image acquisition phases. Significant hematoma expansion and total hematoma enlargement were recorded at 24 hours. Results— Overall (n=371), 77.9% of CTA were acquired in arterial phase. The spot sign, present in 29.9% of patients, was more frequently seen in venous phase as compared with arterial phase (39% versus 27.3%; P =0.041) and the later the phase of image acquisition ( P =0.095). Significant hematoma expansion ( P =0.253) and higher total hematoma enlargement ( P =0.019) were observed more frequently among spot sign–positive patients with earlier phases of image acquisition. Conclusions— Later image acquisition of CTA improves the frequency of spot sign detection. However, spot signs identified in earlier phases may be associated with greater absolute enlargement. A multiphase CTA including arterial and venous acquisitions could be optimal in patients with intracerebral hemorrhage.
H ematoma expansion occurs in approximately one third of patients with acute primary intracerebral hemorrhage (ICH) and is independently associated with early neurological deterioration, death, and disability.1,2 An accurate and reliable method to predict hematoma expansion in patients with acute ICH is needed to improve clinical Background and Purpose-The spot sign score (SSS) provides risk stratification for hematoma expansion in acute intracerebral hemorrhage; however, external validation is needed. We sought to validate the SSS and assess prognostic performance of individual spot characteristics associated with hematoma expansion from a prospective multicenter intracerebral hemorrhage study. Methods-Two hundred twenty-eight intracerebral hemorrhage patients within 6 hours after ictus were enrolled in the Predicting Hematoma Growth and Outcome in Intracerebral Hemorrhage Using Contrast Bolus CT (PREDICT) study, a multicenter prospective intracerebral hemorrhage cohort study. Patients were evaluated with baseline noncontrast computerized tomography, computerized tomography angiography, and 24-hour follow-up computerized tomography. Primary outcome was significant hematoma expansion (>6 mL or >33%) and secondary outcome was absolute and relative expansion. Blinded computerized tomography angiography spot sign characterization and SSS calculation were independently performed by 2 neuroradiologists and a radiology resident. Diagnostic performance of the SSS and individual spot characteristics were examined with multivariable regression, receiver operating characteristic analysis, and tests for trend. Results-SSS and spot number independently predicted significant, absolute, and relative hematoma expansion (P<0.05 each) and demonstrated near perfect interobserver agreement (κ=0.82 and κ=0.85, respectively). Incremental risk of hematoma expansion among spot-positive patients was not identified for SSS (P trend=0.720) but was demonstrated for spot number (P trend=0.050
Background and Purpose-Nine-and 24-point prediction scores have recently been published to predict hematoma expansion (HE) in acute intracerebral hemorrhage. We sought to validate these scores and perform an independent analysis of HE predictors. Methods-We retrospectively studied 301 primary or anticoagulation-associated intracerebral hemorrhage patients presenting <6 hours post ictus prospectively enrolled in the Predicting Hematoma Growth and Outcome in Intracerebral Hemorrhage Using Contrast Bolus Computed Tomography (PREDICT) study. Patients underwent baseline computed tomography angiography and 24-hour noncontrast computed tomography follow-up for HE analysis. Discrimination and calibration of the 9-and 24-point scores was assessed. Independent predictors of HE were identified using multivariable regression and incorporated into the PREDICT A/B scores, which were then compared with existing scores. Results-The 9-and 24-point HE scores demonstrated acceptable discrimination for HE>6 mL or 33% and >6 mL, respectively (area under the curve of 0.706 and 0.755, respectively). The 24-point score demonstrated appropriate calibration in the PREDICT cohort (χ 2 statistic, 11.5; P=0.175), whereas the 9-point score demonstrated poor calibration (χ 2 statistic, 34.3; P<0.001). Independent HE predictors included spot sign number, time from onset, warfarin use or international normalized ratio >1.5, Glasgow Coma Scale, and National Institutes of Health Stroke Scale and were included in PREDICT A/B scores. PREDICT A showed improved discrimination compared with both existing scores, whereas performance of PREDICT B varied by definition of expansion. Conclusions-The 9-and 24-point expansion scores demonstrate acceptable discrimination in an independent multicenter cohort; however, calibration was suboptimal for the 9-point score. The PREDICT A score showed improved discrimination for HE prediction but requires independent validation.
BACKGROUND AND PURPOSE:Recent studies have recommended both early and late imaging to increase spot sign detection. However optimal acquisition timing for spot detection and impact on outcome prediction is uncertain. Our aim was to assess the utility of CTP in spot sign detection and characterization with emphasis on its impact on the prediction of outcome in patients with acute primary ICH.
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