Accuracy of the ABC/2 Score for Intracerebral Hemorrhage

Abstract

Background and Purpose The ABC/2 score estimates intracerebral hemorrhage (ICH) volume, yet validations have been limited by small samples and inappropriate outcome measures. We determined accuracy of the ABC/2 score calculated at a specialized Reading Center (RC-ABC) or local site (site-ABC) versus the reference-standard CT-based planimetry (CTP). Methods In MISTIE-II, CLEAR-IVH and CLEAR-III trials, ICH volume was prospectively calculated by CTP, RC-ABC and site-ABC. Agreement between CTP and ABC/2 was defined as an absolute difference up to 5ml and relative difference within 20%. Determinants of ABC/2 accuracy were assessed by logistic regression. Results In 4369 scans from 507 patients, CTP was more strongly correlated with RC-ABC (r2=0.93) than site-ABC (r2=0.87). Although RC-ABC overestimated CTP-based volume on average (RC-ABC=15.2cm3, CTP=12.7cm3), agreement was reasonable when categorised into mild, moderate and severe ICH (kappa 0.75, p<0.001). This was consistent with overestimation of ICH volume in 6/8 previous studies. Agreement with CTP was greater for RC-ABC (84% within 5ml; 48% of scans within 20%) than for site-ABC (81% within 5ml; 41% within 20%). RC-ABC had moderate accuracy for detecting ≥ 5ml change in CTP volume between consecutive scans (sensitivity 0.76, specificity 0.86) and was more accurate with smaller ICH, thalamic haemorrhage and homogeneous clots. Conclusions ABC/2 scores at local or central sites are sufficiently accurate to categorise ICH volume and assess eligibility for the CLEAR III and MISTIE III studies, and moderately accurate for change in ICH volume. However, accuracy decreases with large, irregular or lobar clots. Clinical Trial Registration MISTIE-II NCT00224770; CLEAR-III NCT00784134; www.clinicaltrials.gov

Retrospective Validation of a Computer-Assisted Quantification Model of Intracerebral Hemorrhage Volume on Accuracy, Precision, and Acquisition Time, Compared with Standard ABC/2 Manual Volume Calculation

“…22,23 It is also wellacknowledged that ABC/2 tends to overestimate lesion volumes. 24,25 In our study, ABC/2 overestimated ICH volume by 45%, on average. While the mean SegTool measurements were .…”

Development and Validation of an Automatic Segmentation Algorithm for Quantification of Intracerebral Hemorrhage

“…Because hematoma size and irregularity in shape or density are often closely correlated, the potential for increased error in larger clots is reasonable for both methods, yet based on different mechanisms. 13,15,22,32 As for the segmentation algorithm, we did not observe a reduction in accuracy associated with antithrombotic drug use. However, our random sample was not balanced regarding this variable to draw final conclusions about the accuracy of the algorithm in patients on antithrombotic drugs.…”

“…Especially, those hematomas were particularly exposed to inaccurate ABC/2 measurements, however, which implies significant volume bias within the surgical cohort. 16,[22][23][24] Regarding our hypothesis, this finding raises the possibility that inaccuracy of ABC/2 is a contributor to inconclusive results regarding surgical outcome after ICH. Moreover, it illustrates why it is of clinical interest to improve methods of ICH quantification to allow for a careful reevaluation of ICH volume as an outcome surrogate.…”

“…13,15,16,22,23 Direct comparison of algorithm and ABC/2 measurements ( Figure 2C) suggests independent errors affecting each respective method because any mutual error-causing disagreement from manual segmentations would be cancelled out in a Bland-Altman comparison. Although error is primarily driven by size, shape, and location in ABC/2, we identified increased misclassification in hematomas exhibiting multiple clot stages and inhomogeneous density in the segmentation algorithm.…”

Early Achievement of Blood Pressure Lowering and Hematoma Growth in Acute Intracerebral Hemorrhage: Stroke Acute Management with Urgent Risk-Factor Assessment and Improvement-Intracerebral Hemorrhage Study

“…Fifth, hematoma volume was assessed using the ABC/2 method. Prior studies have suggested that the ABC/2 method yields hemorrhage volumes smaller than those measured using the planimetric methodology [27] and that the accuracy of this method is decreased when assessing large, irregular, or lobar hematomas [28].…”