Noriyuki Takahashi, Presenter: Nothing to Disclose

Yongbum Lee PhD, Abstract Co-Author: Nothing to Disclose

Du-Yih Tokugi Tsai PhD, Abstract Co-Author: Nothing to Disclose

Kiyoshi Ishii MD, Abstract Co-Author: Nothing to Disclose

In the decision-making process for thrombolysis of hyperacute stroke, parenchymal hypoattenuation are important findings in unenhanced CT, but detectability of the hypoattenuation is largely dependent on skills and experiences of radiologists because detection of hypoattenuation is considerably difficult. We propose a technique to automatically detect hypoattenuation regions in unenhanced CT images, and evaluate the performance of the computer-aided detection (CAD) scheme for detection of parenchymal hypoattenuation of hyperacute stroke.

This technique was based on the comparison between two histograms of CT-values obtained from both cerebral hemispheres. A ROI corresponding to middle cerebral artery (MCA) territory was partitioned into nine rectangular regions. A feature value was obtained by subtracting right-hemispherical histogram from left-hemispherical one in each of the nine regions. The feature value was then used to determine whether hypoattenuation region exists on the ROI. Twenty-six patients with acute (< 5 hours) MCA territory infarction and 30 control subjects were used for performance evaluation. Sensitivity in the detection of hypoattenuation was calculated as a performance criterion. Moreover, the receiver operating characteristic (ROC) curve obtained from the CAD was calculated. Then, it was compared with ROC curves obtained from seven radiologists.

The sensitivity was approximately 92% with 0.16 false-positives per case. Az value, namely the area under ROC curve, of the CAD was 0.973 and average Az value of seven radiologist's ROC curves was 0.885.

The CAD scheme for detection of hypoattenuation can assist radiologists to detect parenchymal hypoattenuation of hyperacute stroke.

This CAD may assist radiologists to detect parenchymal hypoattenuation of hyperacute stroke in unenhanced CT.

Takahashi, N, Lee, Y, Tsai, D, Ishii, K, Computer-aided Detection Scheme for Detection of Hyperacute Stroke in Unenhanced CT.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5006533.html