Zeitaufgelöste 4D CE MRA im Vergleich zur hochortsaufgelösten statischen CE MRA des Unterschenkels

Die Zahl der Patienten, die unter einer peripheren arteriellen Verschlusskrankheit (pAVK) leiden, wächst stetig. Die häufigste Grunderkrankung ist die Atherosklerose, welche meistens auf den ungesunden Lebensstil unserer Gesellschaft zurückzuführen ist. Hauptrisikofaktoren sind die Hyperlipidämie, d...

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Bibliographic Details
Main Author: El Tobgui, Sabrina
Contributors: Heverhagen, Johannes T. (Prof. Dr. Dr.) (Thesis advisor)
Format: Dissertation
Language:German
Published: Philipps-Universität Marburg 2013
Klinik für Strahlentherapie
Subjects:
MRA
Online Access:PDF Full Text
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Table of Contents: The number of patients, who suffer from peripheral artery disease (PAD) increases constantly. The most frequent underlying disease is atherosclerosis, which is a common consequence of the unhealthy lifestyle of western societies. Most common risk factors are hyperlipidemia, diabetes mellitus, high blood pressure, nicotine consumption and increasing age, which, on top of that, is an important factor relating to the prevalence of the PAD. PAD is classified in different stages by pathological factors. Best known are the classifications of Fontaine and Rutherford. Both classifications place the medical condition of the patient in the foreground. An early and safe diagnosis, as well as an accurately timed therapy are very important to avoid a severe course of disease and to improve the prognosis. In 95% of cases a statement can be made by a detailed anamnesis and a thorough physical examination. For more precise assessment of the severity and the localisation of PAD, a more advanced imaging evaluation is necessary. First, digital subtraction angiography should be mentioned, which currently is the gold standard of imaging methods. It offers the possibility of a proper evaluation of the entire vessel section, as well as the option to do interventionel procedures. In the last few years, the diagnostic indications for the digital substraction angiography have been restricted since it also incorporates several risks, such as injuries caused by catheters, contrast media reactions and ionizing radiation. The search for an alternative to the digital subtraction angiography lead to MR angiography (MRA) which benefited from numerous technical improvements. One of those improvements is the possibility to acquire time-resolved, dynamic (4D) images, which are similar to images of the digital subtraction angiography and offers a benefit in detecting the small vessels of the calf, which are often difficult to depict. In this retrospective study, we investigated the benefits with respect to imaging quality of time-resolved, dynamic (4D) ce-MRA compared to high spatial ce-MRA of the lower limb in patients with peripheral artery disease. Another aim of the study was to determine whether one investigator can achieve comparable results with both MRA acquisitions. These investigations included the data of 98 patients and thus 392 MRA angiograms of six vessels of the calf. All 98 patients were included in the study within 1,5 years. It consisted of 58 male and 40 female patients with an average age of 69,7 years (42→89 years). The evaluation of the stenoses, with respect to both observers, yielded ”clinically relevant stenoses“ or complete occlusions for the majority of the vessels (40%). Almost one third of the vessels were assessed as healthy (”no stenosis“). The interobserver comparison, using Cohen ́s Kappa, showed a strong consensus of both investigators for the entire lower leg, for both, the MIP (Maximum Intensity Projection) and the TWIST-analysis (0,712 and 0,642). The intraobserver comparison, using the McNemar’s test, determined significant differences between MIP and TWIST for both observers. The qualitative weighting (evaluation by at least ”good“ qualities of the MRA) showed correlating results to the original results for the interobserver comparison. The intraobserver comparison showed slightly better results. With both MRA-techniques it was possible to achieve comparable results in matters of the detection of stenoses of the lower limb. The assessment of the comparability of the two MRA-techniques showed significant differences for the evaluation of stenoses for both investigators. Technical developments in the field of ce-MRA offer the possibility to detect dynamic images, almost without any quality loss. To remain a reliable diagnostic standard in patiens with PAD, further developments and improvements in this field would be of major importance, e.g. an increase of the contrast-to-noise ratio or the use of 3-tesla systems instead of 1,5-tesla systems.