THE DIAGNOSTIC VALUE OF TRANSORBITAL DOPPLER AND MR ANGIOGRAPHY IN CAROTID SIPHON DISEASE

J Korean Neurol Assoc > Volume 17(1); 1999 > Article

Journal of the Korean Neurological Association 1999;17(1): 20-25.

Carotid Siphon 질환에 있어 경안와 초음파와 자기공명 혈관조영술의 진단적 가치

배희준, 윤병우,노재규

서울대학교 의과대학 신경과학 교실

THE DIAGNOSTIC VALUE OF TRANSORBITAL DOPPLER AND MR ANGIOGRAPHY IN CAROTID SIPHON DISEASE

Hee-Joon Bae, Byung-Woo Yoon, Jae-Kyu Roh Department of Neurology, College of Medicine

Department of Neurology Seoul National University Hospital 28 Yunkeun-dong, Chonro-gu Seoul, 110-744, Korea

Abstract

Background : The aim of this study is to compare the diagnostic power of transorbital Doppler (TOD) and magnetic resonance angiography (MRA) in detecting carotid siphon disease (CSD) confirmed by conventional angiography (CA) and elucidate the diagnostic role of TOD in CSD.
Methods: We recruited the patients who underwent TOD, MRA and CA within 2 months. TOD velocities above 75cm/sec or no flow was defined as abnormal. Carotid siphon on MRA and CA was divided into C2 & C4 segments; stenosis more than 50% or occlusion on the segment corresponding to the flow direction of TOD was defined abnormal.
Results: Sixty patients (44 males and 16 females, mean age: 55.4±12.2 years) were recruited. In 117 available carotid siphons 16 vessels (13.7%) were detected as abnormal by CA, 23 vessels (19.7%) by TOD, and 29 vessels (24.8%) by MRA. When CA was used as a gold-standard, the sensitivity and specificity of TOD were 75.0% and 89.1% while those of MRA were 87.5% and 85.1%, respectively. Positive predictive value was about half (52.2% in TOD and 48.3% in MRA) and negative predictive value was over 95% (95.7% in TOD and 97.7% in MRA). The diagnostic accuracy was 87.2% in TOD and 85.5% in MRA. When TOD and MRA were normal, CA was also normal in 98.7% and when both tests were abnormal, CA was abnormal in 78.6%. But when one of two tests was abnormal, CA was abnormal only in 16.7%. Diagnostic consistency of TOD & MRA was acceptable (kappa value = 0.409). Among 23 carotid siphons, which were abnormal on TOD, 11 vessels were normal on CA; false positive rate was 47.8%. But we could find the presumed causes of false positive results in most of cases, such as contralateral proximal ICA occlusion, ipsilateral ICA stenosis just proximal to carotid siphon, etc.
Conclusions: Transorbital Doppler is as good as MRA in noninvasive detection of carotid siphon disease. Despite of the relatively low positive predictive value of TOD and MRA, the combination of their results increases the diagnostic accuracy in carotid siphon disease and may reduce the need of conventional angiography. Key words: Tranorbital Doppler, Transcranial Doppler, Magnetic resonance angiography, Carotid siphon, Carotid siphon disease, Cavernous ICA