EVALUATION OF 3 DFT TIME-OF-FLIGHT MR-ANG IOGRAPHY VERSUS ANGIOGRAPHYIN THE EXPLORATION OF ATHEROMATOUS LESIONS OF THE CAROTID-ARTERY - REVIEW OF THE LITERATURE

In 37 patients suspected of having a stroke 71 carotid bifurcations we re explored by MR-angiography and by digital angiography, the referenc e technique. A 3D sequence was acquired with the time-of-flight techni que, using a transmitter-receiver cranial coil, followed by a strictly receiver Helmoltz coil on a 1 Tesla magnet. Two examiners evaluated t he carotid bifurcations and measured the degree of stenosis in terms o f diameters, according to the North American Symptomatic Carotid Endar terectomy Trial (NASCET). Five classes were established : class 1:norm al; class 2:1 to 29 %; class 3:30 to 69 %; class 4:70 to 99 % and clas s 5:thrombosis. The results obtained in the determination of classes w ere identical with both coils : the coefficient of correlation with st raight angiography were 0,973 with the cranial coil and 0,966 with the Helmoltz coil. Five stenoses were overestimated and classified as Cla ss 3 instead of Class 2. The five stenoses greater than 70 % (Class 4) showed a signal-void area at their level, due to severe dephasing ind uced by turbulences. Finally, there was a false-negative image of occl usion : the high-intensity signal of the thrombus was mistaken for one of flow. The data of our study were in accordance with the excellent results obtained by several authors in the literature, which makes it possible for us to propose this type of examination as a novel mean of investigating bifurcations of carotid arteries. Provided a strict tec hnique is applied, and in addition to carotid bifurcation the Willis'c ircle and the cerebral parenchyma are explored, MR-angiography can com plete the results of Doppler-echo. Standard arteriography could then b e reserved to surgical patients and to those with discordant results o f MR-arteriography and Doppler echo systems.