Purpose
The CT angiography (CTA) spot sign is a strong predictor of hematoma expansion in intracerebral hemorrhage (ICH). However, CTA parameters vary widely across centers and may negatively impact spot sign accuracy in predicting ICH expansion. We developed a CT iodine calibration phantom that was scanned at different institutions in a large multicenter ICH clinical trial to determine the effect of image standardization on spot sign detection and performance.
Methods
A custom phantom containing known concentrations of iodine was designed and scanned using the stroke CT protocol at each institution. Custom software was developed to read the CT volume datasets and calculate the Hounsfield Unit as a function of iodine concentration for each phantom scan. CTA images obtained within 8 h from symptom onset were analyzed by two trained readers comparing the calibrated vs. uncalibrated density cutoffs for spot sign identification. ICH expansion was defined as hematoma volume growth >33%.
Results
A total of 90 subjects qualified for the study, of whom 17/83 (20.5%) experienced ICH expansion. The number of spot sign positive scans was higher in the calibrated analysis (67.8% vs 38.9% p<0.001). All spot signs identified in the non-calibrated analysis remained positive after calibration. Calibrated CTA images had higher sensitivity for ICH expansion (76% vs 52%) but inferior specificity (35% vs 63%) compared with uncalibrated images.
Conclusion
Normalization of CTA images using phantom data is a feasible strategy to obtain consistent image quantification for spot sign analysis across different sites and may improve sensitivity for identification of ICH expansion.
Background and Objective:
Transcranial Doppler (TCD) is endorsed by the American Heart Association/American Stroke Association, the American Academy of Neurology, and the Neurocritical Care Society for use in aneurysmal subarachnoid hemorrhage (aSAH) for surveillance of cerebral vasospasm (CV). However, data on utilization of TCD for CV detection and monitoring in aSAH are lacking. We estimated the proportion of patients with aSAH receiving TCD monitoring using the Nationwide Inpatient Sample (NIS).
Methods:
Data from 2002-2011 NIS were used to calculate the number of discharges with a primary diagnosis of aSAH per 100,000 discharges. Descriptive analysis of nationwide trends in TCD prevalence was performed. Teaching hospitals were examined separately for TCD utilization rates and this was done biennially to prevent small numbers.
Results:
Between 2002 and 2011, a total of 256,089 patients were discharged with a diagnosis of aSAH of which 3,850 underwent TCD monitoring. aSAH accounted for an average of 67.1 discharges per 100,000 annually (95% CI 61.3-72.8) from 2002-2011. Of these, only 1.5% (95% CI 0.4-2.6) underwent TCD examination. In teaching hospitals, aSAH accounted for an average of 108.5 discharges per 100,000 biennially (95% CI, 96.2-120.8), of which 2% (95% CI 1.0-4.0) underwent TCD examination. TCD utilization increased from <1% during the 2002-2005 period, to ≥1.5% during the 2006-2011 period (OR 2.3, 95% CI 1.0-5.7), an increase also seen in teaching hospitals.
Conclusion:
TCD is underutilized nationally in the care of aSAH. While the prevalence of TCD is low in teaching hospitals, it is nearly nonexistent in non-teaching hospitals.
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