The magnetic resonance imaging for aortic lesions

The magnetic resonance imaging (MRI) was applied for the various type of aortic lesions such as saccular and fusiform type of thoracic and abdominal aneurysm, aortic dissection in acute and chronic phase and pseudocoarctation caused by aortitis syndrome. Their results were analysed and compared to the conventional diagnostic tools of X-ray CT scan and DSA angiography. For the application to aneurysmal disease of the aorta, visualization of the pathology was clearly demonstrated, especially anatomical relationships of the lesion to the cervical branches and abdominal major branches were well demonstrated, for which conventional methods sometimes could not give full information. The MRI study was undertaken to various types of aortic dissection. In DeBakey type I, visualization of true and pseudolumen was well. The intimal flap was also well demonstrated in all the planes of examination, however, detection of the anatomical location of initial tear was failed. Some difficulties were encounter to evaluate the pathological changes occurring at the aortic arch, additional study such as projection by oblique plane might contribute for the better and fine demonstration of the pathology. Type III dissection is usually most clearly diagnosed by either CT and angiography. Consequently, pseudolumen of this dissection is apt to close by thrombus formation in the early phase. Angiography usually does not demonstrate the entry itself and the diagnosis of dissection will not establish by this method. However by taking enhanced CT, characteristic findings of thrombosed dissection will be obtained and the diagnosis of this particular type is firmly established. The incidence of this type is high as over 20 % in our institution. The contribution of the MRI for this is expecting by further experiences. (J.P.N.)