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1 Minimally Invasive Diagnosis of Vascular Disease by MDCT: Current Status of Three-dimensional CT Angiography and Its Potential as a Method for Treatment Planning Department of Radiology and Center for Advanced Medical Technology Nippon Medical School Hiromitsu Hayashi, M.D., Ryo Takagi, M.D., Katsuya Takahama, M.D., Toshihide Kaizu, M.D., Yasuhiro Shimizu, M.D., Ryo Matsuda, M.D., Nobuyuki Tateno, M.D., Shigehiko Kuribayashi, M.D., Fumitaka Hidaka, M.D., Hisashi Yoshihara, M.D., Hidetaka Satou, M.D., Tomoyuki Kuwako, M.D., and Tatsuo Kumazaki, M.D. NICHIDOKU-IHO Vol. 50 No (2005) Summary Computed tomography (CT) is an objective, minimally invasive diagnostic technique that can be performed rapidly, enabling evaluation of the vascular wall, where the true nature of vascular disease is found. In many instances, however, conventional CT has not served as the primary diagnostic test, presumably for the following reasons: mechanical limitations, such as the significant partial volume effect resulting from the large slice thickness and poor differentiation of the small vessels due to the decline in contrast enhancement with the prolongation of examination time; the complexity of constructing the vasculature three-dimensionally in mind from a number of slice images; and the difficulty of diagnosing any stenotic or occlusive lesions in this difficult process. Nevertheless, recent advances in diagnostic imaging have been outstanding. In the area of CT, the advent of helical CT has made it possible to obtain volumetric data sets with favorable continuity in the body axis direction within a short examination time, and has opened the way to three-dimensional CT angiography (CTA). Furthermore, following helical CT, multidetector row CT (MDCT) has been developed. Consequently, it is now possible to examine a large area over 1 m in length with spatial resolution of 1 mm or less in the body axis direction within only about 10 seconds. For aortic aneurysm, CTA can provide the following information: location, morphological type, presence of intraluminal thrombus, relation with the major branches or the surrounding organs, any complications including peripheral arterial occlusive disease, and quantitative evaluation of the aneurysm. Three-dimensional CTA can be used in preoperative simulation of the procedure or as reference imaging for informed consent. CTA also can enable qualitative and quantitative evaluation of treatment response, together with evaluation of complications after treatment. In cases of aortic dissection, CTA can provide sufficient information on the classification of disease, including the extent of involvement or status of the false lumen. To determine the extent of dissection to the major branches, angiography conventionally has been used, but CTA also can be used with its improved spatial resolution. CTA also is useful to evaluate thrombus formation in the remaining false lumen or to provide quantitative evaluation of aortic

2 dilation after surgical or endovascular intervention. Paraplegia of the lower extremities may occur immediately after the onset of aortic dissection or after surgery for aortic aneurysm or dissection. As a possible cause, spinal cord ischemia due to occlusion of the Adamkiewicz artery has been considered. With MDCT, the Adamkiewicz artery can be visualized in as many as 70 90% of cases, and MDCT is considered to be promising as a minimally invasive diagnostic method. Peripheral arterial occlusive disease is a disease with atherosclerotic change predominantly of the main trunk arteries of the upper and lower extremities, resulting in stenosis or occlusion of the artery, thereby causing ischemic lesions of varying degree in the peripheral areas. In association with recent westernization of the diet and aging resulting from prolongation of the average lifespan, peripheral arterial occlusive disease is increasing in Japan. CTA can provide the location and extent of the lesion, morphological type of stenosis and stenotic ratio, characteristics of the vascular wall of the lesion and evaluation of the vasculature distal and proximal to the target lesion, diagnosis of any multiple concurrent lesions, and evaluation of any collateral circulation and peripheral run-off. It has been reported that, compared with angiography, MDCT angiography provides favorable diagnosis of stenotic or occlusive lesions, with sensitivity of 89 96%, specificity of 86 93%, and accuracy of diagnosis of 94%. After surgical or endovascular treatment, CTA enables treatment efficacy to be assessed, provides evaluation of multiple lesions, and is able to search for any new lesions. It has been just 10 years since CTA was introduced for practical use in the clinical field, and diagnostic imaging in vascular diseases has been steadily shifting from invasive angiography to this minimally invasive diagnostic method. Presently, active efforts are ongoing for the further development and improvement of MDCT, and, in this respect, CTA can be considered a diagnostic method that is still in the developmental process. It is expected that MDCT and CTA will be further improved in the future to be less invasive while providing more biological information.

4 日獨医報第50巻第 1 号 2005 LSCA A A B B 図 2 症例 2 遠位弓部の紡錘状大動脈瘤のCTA 左鎖骨下動脈 LSCA 分岐直後の遠位弓部に紡錘状の大動脈瘤を認める矢印厚い壁在血栓矢頭も同時に描出することが可能である図3 A B C D 症例 3 腎動脈分岐下腹部大動脈瘤破裂の2D画像ならびにcarved planar reconstruction CPR 像 CTA A CTAの元画像にて腎動脈分岐下の腹部大動脈瘤と後腹膜血腫を認める B 腹部大動脈から右外腸骨動脈の走行に沿ったCPR像にて後腹膜腔に連続する血腫を認める右外腸骨動脈の狭窄矢印および左内腸骨動脈に瘤の合併を認める C CTAにて腹部大動脈瘤の破裂部に一致するくちばし状の突出部を認める矢印

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49-4 ™ñ„¾ Œ]„”†i4†j

49-4 ™ñ„¾ Œ]„”†i4†j Current Topics in Diagnostic Imaging of the Pediatric Neck Eiji Oguma, M.D. Department of Radiology, Saitama Children s Medical Center NICHIDOKU-IHO Vol. 49 No. 4 61 83 (2004) Summary This article focuses