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Habs, Maximilian (2012): Morphologische und funktionelle Bildgebung mittels hochauflösender 3.0 Tesla Multi-Sequenz Magnetresonanztomographie und 18F-Fluorodesoxyglukose PET Computertomographie bei Patienten mit spontanen Dissektionen der Halsgefäße. Dissertation, LMU München: Medizinische Fakultät
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Abstract

Between 2007 and 2010 more than 50 patients with spontaneous dissections of cervical arteries have been examined and scanned with a modified cervical MRI and fluorodeoxyglucose (18F) PET CT protocol at the Institute of Clinical Radiology, LMU Munich. Within this prospective, mono-centric study all imaging data was obtained by using a 3.0 tesla scanner (Magnetom Verio; Siemens Healthcare) and two PET CT scanners (Philips Gemini; Philips Healthcare and Siemens Biograph 64; Siemens Healthcare). This study was based on and conducted by a strong cooperation between the Department of Neurology and the Department of Nuclear Medicine. Detailed data sets regarding patient history and clinical parameters were recorded for every patient. The MRI protocol included a time-of-flight angiography, fat-saturated T1- and T2- weighted black-blood sequences before and after the administration of contrast medium (Gadovist®, Bayer-Schering). The scans covered the supra-aortic vessels from the aortic arch to the base of the skull with a best in plane resolution of 0.5 x 0.5 mm2. Every patient received an additional diffusion-weighted brain-MRI for evaluation of ischemia. The supra-aortic vessels of the same patients were also scanned by a low dose FDG/PET-CT. Measurements of standardized uptake values for every vessel segment were obtained after the administration of the tracer (activity: 5 MBq/kg bodyweight). The calculated effective dose was 8 mSv per patient. Along with quantitative PET-CT analysis, experienced radiologists performed qualitative evaluation of vessel wall inflammation for PET-CT and the MR images. Local inflammatory changes at the site of dissection were distinguished from generalized inflammation of the vascular system.

Abstract

For the study of Pfefferkorn et al (Stroke 2011) 37 patients with spontaneous cervical dissection matched the inclusion criteria. In 27 patients (83%) PET-CT showed significant perivascular FDG-uptake at the site of dissection. 8 Patients (24%) showed signs of generalized inflammation with increased FDG-uptake at additional vessel segments (e.g. aortic arch). We found a strong positive correlation between the presence of dissection and perivascular contrast enhancement (Pearson´s r=0.73; p<0.001) and perivascular edema (r=0.65; p<0.001) as determined by MRI. All Patients with inflammatory changes seen by MRI and/or PET-CT showed complete remission in the follow-up scan after 3 month. This study demonstrated the high prevalence of inflammatory changes at the site of dissection, which can be detected by MRI and PET-CT. Furthermore the study showed that generalized vessel wall inflammation is present in small subgroup of patients, suggesting that vascular inflammation plays an important role in the pathogenesis of cervical artery dissections.

Abstract

The study of Habs et al (JCMR 2011) investigated the age determination of vessel wall hematomas by MRI in 35 patients with spontaneous cervical artery dissection. The vessel wall hematomas were classified according to their relative signal intensities on T1- and T2-weighted images and were described as either acute, early subacute, late subacute or chronic. Only patients with a clear clinical onset of symptoms typical for cervical artery dissection (e.g. Horner's syndrome, TIA, stroke) were included in this study, so that the age of the dissection could be determined. Based on the MRI assessment of the vessel wall hematomas the mean age of the dissection for early subacute, late subacute and chronic appearance of the hematoma differed significantly from each other (5.8 vs. 15.7 vs. 58.7 days). There was a strong agreement between the MRI based classification and the age of the hematoma (Cohen´s kappa 0.74; p<0.001). In a nutshell, MR signal intensities of vessel wall hematomas in patients with cervical artery dissections change over time, which can be a useful tool to evaluate the age of a dissection in patients with unclear onset of symptoms or unspecific presentation.