Quantification of image contrast of infarcts on computed tomography scans

Introduction Accurate identification of infarcts in non-contrast computed tomography (NC-CT) scans of the brain is fundamental in the diagnosis and management of patients with stroke. Quantification of image contrast properties at the boundaries of ischemic infarct regions in NC-CT can contribute to...

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Bibliographic Details
Published in:	The neuroradiology journal Vol. 30; no. 1; pp. 15 - 22
Main Authors:	Gomolka, RS, Chrzan, RM, Urbanik, A, Kazmierski, R, Grzanka, AD, Nowinski, WL
Format:	Journal Article
Language:	English
Published:	London, England SAGE Publications 01-02-2017
Subjects:	Adult Aged Aged, 80 and over Analysis of Variance Brain Imaging Brain Infarction - diagnostic imaging Brain Infarction - etiology Brain Ischemia - complications Contrast Media - metabolism Female Humans Longitudinal Studies Male Middle Aged Retrospective Studies Statistics as Topic Stroke - complications Stroke - diagnostic imaging Stroke - etiology Time Factors Tomography, X-Ray Computed Stroke tissue contrast NC-CT computer-aided diagnosis
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Summary:	Introduction Accurate identification of infarcts in non-contrast computed tomography (NC-CT) scans of the brain is fundamental in the diagnosis and management of patients with stroke. Quantification of image contrast properties at the boundaries of ischemic infarct regions in NC-CT can contribute to a more precise manual or automatic delineation of these regions. Here we explore these properties quantitatively. Methods We retrospectively investigated 519 NC-CT studies of 425 patients with clinically confirmed ischemic strokes. The average and standard deviation (SD) of patients’ age was 67.5 ± 12.4 years and the average(median)±SD time from symptoms onset to NC-CT examination was 27.4(12)±35.7 h. For every scan with an ischemic lesion identified by experts, the image contrast of the lesion vs. normal surrounding parenchyma was calculated as a difference of mean Hounsfield Unit (HU) of 1–5 consecutive voxels (the contrast window width) belonging to the lesion and to the parenchyma. This contrast was calculated at each single voxel of ischemic lesion boundaries (previously delineated by the experts) in horizontal and vertical directions in each image. The distributions of obtained horizontal, vertical and both contrasts combined were calculated among all 519 NC-CTs. Results The highest applicative contrast window width was identified as 5 voxels. The ischemic infarcts were found to be characterized by 6.60 HU, 8.28 HU and 7.55 HU mean values for distributions of horizontal, vertical and combined contrasts. Approximately 40–50% of the infarct boundary voxels were found to refer to the image contrast below 5 HU. Conclusion Low image contrast of ischemic lesions prevents accurate delineation of the infarcts in NC-CT.
ISSN:	1971-4009 2385-1996
DOI:	10.1177/1971400916678226