Evaluation of transcranial color-coded duplex sonography for cerebral artery stenosis or occlusion.

BACKGROUND AND PURPOSE

Cerebral artery stenosis or occlusion is the most common etiological factor in patients with acute cerebral ischemia, but the rate of early diagnosis is low. The purpose of the study is to evaluate the diagnostic accuracy of transcranial color-coded sonography (TCCS) for cerebral artery stenosis with digital subtraction angiography used as the gold standard of reference.

METHODS

Seventy-eight patients who were suspected of cerebrovascular disease were involved in the study. Major cerebral arteries were observed through the transcranial echo window by TCCS. The course, shape of the color blood beam and velocity were given special attention. The hemodynamic parameter was measured and analyzed. The findings of TCCS were compared with the results of digital subtraction angiography, according to a double-blind design. A 4-fold table was used as the statistical analysis method to evaluate TCCS. The indexes included sensitivity, specificity, accuracy and false-positive rate.

RESULTS

Imaging of TCCS revealed that the blood flow beam narrowed where the artery had stenosis and looked like girdling. The velocity of the foci increased abnormally, while the velocity before and after the foci decreased. Severe stenosis and the long stenotic segment may show discontinuity of the blood flow beam. The velocity of the foci did not noticeably increase or decrease. The blood flow beam of the occlusive artery cannot be seen and the frequency spectrum cannot be obtained, but the other artery was well visualized at the same time. Analysis of the diagnostic value of TCCS according to the 4-fold table included the validity index, with a sensitivity, specificity, false-positive rate, false-negative rate, accuracy, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio and Youden index of 72.9%, 82.9%, 17.1%, 27.0%, 78.2%, 79.4%, 77.3%, 4.3, 0.3 and 0.56, respectively. The reliability index included the agreement rate and kappa value, which were 78.2% and 0.56, respectively.

CONCLUSIONS

TCCS could be considered a valuable method for the screening diagnosis of cerebral artery stenosis or occlusion.