Clinical Application Of Contrast-enhanced MRA On Peripheral Vascular Diseases

With the improvement of the standard of living, the morbidity of the peripheral artery stenosive or occlusive diseases, include the arteriosclerosis, the diabetes related blood vasculitis and the artery embolism, is also increasing. Therefore, 3D CE MRA, as a very important non-intervene diagnosis method for the vascular disease, will bring into play a great effect, although we treat DSA as gold standard at all times. With rapid advancing of MRI and computer technology, it has taken a tendency that 3D CE MRA will replace DSA.We retrospected 97 patients with full imaging information to probe the value of clinical application of 3D CE MRA for diagnosis peripheral artery stenosive or Occlusive diseases and to assess its accuracy. Taking DSA and operation as gold standard, to compare 3D CE MRA with DSA in assessing vascular stenosis or occlusion and to probe if the technique Of 3D CE MRA could replace DSA is the objective of this study. We also simulated the feint during the course of clinical application to study the reason of the false positive. This would provide the scientific evidences for diagnosing and treating the PAOD.In the clinical study, all the patients with PAOD were convicted by the operation and all of them underwent 3D CE MRA before it. The examinations were performed on a 1.5T MRI scanner (Simens Erlangen), in combination with a receive-only single coil. And the patient was to remain in the supine position. Three dimensional spoiled GRE was used. The contrast medium was injected with dual rate, the former injection rate was 3ml/s in the front 25ml, and the latter was 0.6-0.8ml/s in the last 20ml. The pre-contrast mask sequence was then subtracted from the post-contrast sequence acquired. Then maximum intensity projections were calculated from the subtracted data sets. The stenotic degree of peripheral artery was divided into positive (＞=70%) or negative(＜70%) and the whole artery was divided into 3 sections. Taking DSA or operation as gold standard, the sensitivity, specificity and accuracy of 3D CE MRA were calculated. Identified by surgery, 579 sections (negative 453, positive 126) of 103 patients were found, the false negative in 2 and the false positive in 21. The sensitivity, specificity and accuracy of3D CE MRA were 95%, 97% and 96.6% for iliac artery, 98.1%, 96.5% and 96.4% for femoral artery, 100%, 92.4% and 93.9% for tibiofibular artery. The total sensitivity, specificity were 97.6%, 95.4%.This proves that the accuracy of the positive is very higher.Stenotic or occlusive vessels were examined by means of 3D CE MRA and DSA. And the degree and length of target stenotic or occlusive vessels were measured respectively. The results of 3D CE MRA were compared with the findings on DSA.All cases were classified as good image quality. The rate of satisfactory of vessel visualization for 3D CE MRA was 100%. Taking the image of DSA as standard, the image quantity of 3D CE MRA is very good as well as that of DSA. The degree of stenosis measured by 3D CE MRA was higher than that of DSA, especially for severe stenosis. In other words, there was a little overestimation. There was a little difference between the degree of stenosis measured by 3D CE MRA and DSA (p＜0.05), however, there was no significant difference between them if taking clinical classification of the stenostic degree as standard. Also, there was good Correlation between stenosis length measurements on 3D CE MRA and those on DSA (p＞0.05). Assessing the position of complete obstruction, there was always a length between the displayed position and the real, which was measured either by the two techniques. There was no significant difference between the lengths measured by 3D CE MRA and DSA (p＞0.05).In summary, through assessing the artery stenosis or occlusion, it is demonstrated in our study: 3D CE MRA is accurate and reliable for determination of the degree and length of peripheral artery stenosis or occlusion. There is no significant difference between 3D CE MRA and DSA. This experiment would provide scientific evidence for 3D CE MRA replacing DSA.