[en] Purpose: The increased T1 relaxation times at 3.0 Tesla lead to a reduced T1 contrast, requiring adaptation of imaging protocols for high magnetic fields. This prospective study assesses the performance of three techniques for T1-weighted imaging (T1w) at 3.0 T with regard to gray-white differentiation and contrast-to-noise-ratio (CNR). Materials and Methods: Thirty-one patients were examined at a 3.0 T system with axial T1 w inversion recovery (IR), spin-echo (SE) and gradient echo (GE) sequences and after contrast enhancement (CE) with CE-SE and CE-GE sequences. For qualitative analysis, the images were ranked with regard to artifacts, gray-white differentiation, image noise and overall diagnostic quality. For quantitative analysis, the CNR was calculated, and cortex and basal ganglia were compared with the white matter. Results: In the qualitative analysis, IR was judged superior to SE and GE for gray-white differentiation, image noise and overall diagnostic quality, but inferior to the GE sequence with regard to artifacts. CE-GE proved superior to CE-SE in all categories. In the quantitative analysis, CNR of the based ganglia was highest for IR, followed by GE and SE. For the CNR of the cortex, no significant difference was found between IR (16.9) and GE (15.4) but both were superior to the SE (9.4). The CNR of the cortex was significantly higher for CE-GE compared to CE-SE (12.7 vs. 7.6, p<0.001), but the CNR of the basal ganglia was not significantly different. Conclusion: For unenhanced T1w imaging at 3.0 T, the IR technique is, despite increased artifacts, the method of choice due to its superior gray-white differentiation and best overall image quality. For CE-studies, GE sequences are recommended. For cerebral imaging, SE sequences give unsatisfactory results at 3.0 T. (orig.)

[en] Aim: To evaluate the impact of bone subtraction computed tomography angiography (BS-CTA) for the assessment of transcranial arteries in comparison with standard CTA (S-CTA) without bone removal and time-of-flight magnetic resonance angiography (TOF-MRA). Materials and methods: Cranial unenhanced CT and S-CTA were performed in 53 patients with suspected cerebrovascular disease. BS-CTA datasets were reconstructed from the S-CTA and unenhanced CT source images. TOF-MRA was performed within 24 h after CTA on a 1.5 T MRI system. Two radiologists, in consensus, evaluated the segments of the internal carotid artery (C2-C7), the vertebral artery (V4), and the basilar artery for the degree of stenosis. A five-step scale (0-49, 50-69, 70-89, 90-99% and occlusion) for the degree of stenosis was applied for all segments. Wilcoxon's signed rank test was used for statistical analysis. Results: Seven hundred and fifty vessel segments (ICA:636, VA:106, BA:53) were analysed. The degree of stenosis on S-CTA was consistent with TOF-MRA in all segments. BS-CTA showed a trend towards higher stenosis scores in cases of calcified plaques compared to S-CTA (p = 0.11) and TOF-MRA (p = 0.09), which was not statistically significant. In transcranial segments, BS-CTA revealed equivalent scores compared to S-CTA and TOF-MRA (p = 0.25; p = 0.20). Conclusion: BS-CTA produced similar results to TOF-MRA and S-CTA and can be applied as a non-invasive imaging method for the transcranial arteries. However, BS-CTA shows a trend towards overestimation of the degree of stenosis.

[en] Purpose: Aim of this prospective study was to investigate the incidence of spontaneous cervical artery dissection (sCAD) and cerebral ischemia in patients with suspected sCAD by using a combined head-neck MR-imaging protocol. Materials and Methods: 51 consecutive patients (24 m, 27 f, mean age 39.5 years, range 18 - 55 yrs) admitted to our stroke unit with suspected sCAD according to clinical criteria and age <55 years underwent a combined head and neck MR examination within 24 hours of admission (Gyroscan Intera 1.5 T, Philips). Head MRI included ax FLAIR, ax T₁, ax DWI and TOF angiography (imaging time 12 min). Neck MRI consisted of ax T1w-TSE, T2w-TSE, contrast enhanced T1w-TSE and CE-MRA (imaging time 17 min). Three radiologists assessed both studies in consensus with regard to the presence of sCAD and acute ischemia. Results: One patient had to be excluded because of motion artefacts. In 17 of 50 patients sCAD was diagnosed, and in 20 of 50 patients cerebral ischemia. In 5 patients cerebral ischemia was caused by sCAD. Conclusion: The proposed combined MR protocol allows imaging work-up of patients with suspected sCAD within approximately 30 min, resulting in conclusive information about the status of the extracranial vasculature and the presence of ischemia. The high incidence of patients with definite sCAD and the low incidence of cerebral ischemia indicates the necessity of an early definite diagnosis in order to start timely anticoagulation to prevent development of stroke. (orig.)