CT angiographic measurement of the carotid artery: Optimizing visualization by manipulating window and level settings and contrast material attenuation

Citation
Y. Liu et al., CT angiographic measurement of the carotid artery: Optimizing visualization by manipulating window and level settings and contrast material attenuation, RADIOLOGY, 217(2), 2000, pp. 494-500
Citations number
21
Categorie Soggetti
Radiology ,Nuclear Medicine & Imaging","Medical Research Diagnosis & Treatment
Journal title
RADIOLOGY
ISSN journal
00338419 → ACNP
Volume
217
Issue
2
Year of publication
2000
Pages
494 - 500
Database
ISI
SICI code
0033-8419(200011)217:2<494:CAMOTC>2.0.ZU;2-6
Abstract
PURPOSE: To evaluate a broad range of window and level settings for various contrast material attenuation coefficients and degrees of vascular stenosi s to obtain the most accurate computed tomographic (CT) angiographic measur ements. MATERIALS AND METHODS: A total of 25,480 measurements were made transversel y (perpendicular to the lumen) and by means of maximum intensity projection (M/P) in a phantom with stenoses of 0%-100%, contrast material with attenu ation coefficients of 150-350 HU, and 14 window and 13 level settings. Edge definition was also evaluated. RESULTS: There was an inherent relationship between the contrast material a ttenuation coefficient and the optimal window and level settings in the mea surement of stenoses at both transverse and MIP CT angiography. This relati onship between the contrast material attenuation coefficient D and the opti mal settings for window Wand level L was represented by the following simpl e equations: W/D = [-2 x (L/D)] + 1.3, where -0.2 < L/D < 0.5, and W/D = [3 .3 x (UD)] - 1.3, where 0.5 < LID < 1.0. With a vascular contrast material attenuation coefficient of 250-350 HU, the best transverse and MIP display settings for the window and level were 96 and 150 HU, respectively. CONCLUSION: The use of optimized window and level settings at CT angiograph y reduces measurement variability.