Non-invasive diagnostic methods of intracranial arteries

Sammanfattning: Aims of this thesis were to compare the agreement of different magnetic resonance angiography(MRA) techniques and digital subtraction angiography (DSA) in follow-up of intracranial aneurysms treated with coils in order to select the best MRA method, to evaluate the impact of increased iodine concentration in contrast medium and decreased tube voltage on arterial attenuation and image quality in computed tomography angiography (CTA) of intracranial arteries, and finally to evaluate the diagnostic accuracy of CTA in non-traumatic subarachnoid haemorrhage (SAH) compared to DSA and to assess the arterial attenuation (HU) as an image quality factor in this aspect. Follow-up DSA and time-of-flight (TOF) MRA at 1.5T and 3T as well as contrast-enhanced MRA at 3T were performed in 37 patients with 41 coiled intracranial aneurysms. TOF-MRA at 3T showed best agreement with DSA. One of three different combinations of iodine concentrations in contrast medium and CT tube voltages was tested in each of 63 patients referred for CTA of intracranial arteries. Increased iodine concentration (400 mgI/ml) and decreased tube voltage (90 kVp) improved image quality in CTA of intracranial arteries and arterial attenuation at 340 HU in the ICA was found to represent a cut-off level for examinations of good quality. In 326 patients with non-traumatic SAH, diagnostic accuracy and arterial attenuation (HU),reflecting image quality, were assessed for CTA. CTA can be performed with high sensitivity(95%) and specificity (97%) for detection of ruptured aneurysms in the acute setting of SAH and arterial attenuation is correlated to the sensitivity.