Magnetic resonance angiography of spontaneous vertebral artery dissection suspected on Doppler ultrasonography.

Spontaneous vertebral artery dissection (VAD) is a rare but well-known cause of cerebrovascular disease and is often difficult to diagnose even using conventional arteriography. While noninvasive tests such as Doppler ultrasonography and magnetic resonance imaging (MRI) have failed to provide reliable criteria for the diagnosis of VAD, the diagnostic value of magnetic resonance angiography (MRA) has not yet been undetermined. To establish the reliability of a combined noninvasive approach, 11 patients were prospectively examined for VAD by means of colour-coded duplex studies, MRI and three-dimensional time-of-flight MRA prior to conventional angiography. Among 11 patients with VAD suspected clinically as well as on Doppler ultrasonography, angiography confirmed the diagnosis in seven patients but found a vertebral artery occlusion in three and a vertebral artery stenosis in one. The combination of MRI and MRA findings led to the correct diagnosis of dissection in three patients, of vertebral artery occlusion in three patients, and of vertebral artery stenosis in one. VAD was misinterpreted as vertebral artery occlusion in four patients. Doppler ultrasonography is a valuable screening method for the detection of vertebral artery pathologies. The diagnosis of VAD can only be established if a typical intramural vessel wall haematoma is seen on T1-weighted MRI in combination with MRA findings of irregular artery stenosis or occlusion.