gms | German Medical Science

Objective: The potential of ultrahigh-field magnetic resonance imaging (UHF-MRI) at 7 Tesla (T) in cerebrovascular disease has been shown recently. A major benefit is expected for MR-angiography (MRA) due to increased spatial resolution and novel contrast mechanisms. 7 T MRA might therefore contribute substantial impact for the diagnosis of moyamoya disease (MMD), which is characterized by slowly progressive occlusion of major cerebral arteries and prominent collateral artery formation. In MMD, to date digital subtraction angiography (DSA) is the gold standard for assessment of preoperative vessel status for extra-intracranial (EC-IC) bypass surgery. We hypothesized that UHF-MRI at 7 T can yield preoperative diagnostic information equivalent to DSA for planning of EC-IC bypass surgery.

Method: In an ongoing, WHO-registered and prospective imaging trial (7UP, WHO-register No. DRKS00003193) three patients suffering from MMD were investigated at 7 T (Magnetom 7 T, Siemens Healthcare, Erlangen, Germany) and at 3 T (Magnetom Verio) prior EC-IC BS. 7 T MRA included MPRAGE-MRA (resolution: 0.7 mm isotropic, whole brain coverage, acquisition time (TA): 6:40 min) and time-of-flight (TOF)-MRA (0.4 mm isotropic, 5.1 cm coverage, TA: 8:16 min). At 3 T, TOF-MRA was performed (0.6 mm isotropic, 8.2 cm coverage, TA: 5:54 min). MRI was compared to DSA performed during presurgical planning. All patients gave written informed consent prior to the study.

Results: In all three patients, 3 T TOF MRA and 7 T MPRAGE MRA were able to depict the complete major vascular tree and showed MMD specific stenosis or occlusion of a major cerebral artery as identified prior by DSA (middle cerebral artery (MCA): n=2 / internal carotid artery (ICA): n=1). In contrast to 3 T MRI, 7 T MRI depicted small moyamoya specific vessels (7 T TOF MRA) and identified donor vessels (7 T MPRAGE MRA) for EC-IC bypass surgery.

Conclusions: Our preliminary results indicate that a specific 7 T vascular imaging protocol might yield diagnostic information about vessel pathology in MMD that approximate conventional DSA. This finding is promising and will be validated in a larger patient sample.