Three-dimensional DCE MRA: Significance In The Classification Of Peripheral Arterial Occlusive Disease

BackgroundPeripheral arterial occlusive disease (PAOD) refers to peripheral arterial stenosis or occlusion caused by a variety of reasons, which may lead to distal tissue ischemic or necrosis. The patient's lower limb artery, carotid artery, renal artery and the superior mesenteric artery can be affected. In the lower limb artery, the area above the femoral artery and the poptiteal artery is more commonly affected. The most commonly affected area is the bifurcation of the artery. The common cause of the disease is arteriosclerosis, mostly found in the elderly. The incidence of the disease is higher and higher, with the improving of the life level and the changing of the dietary structure in China. The clinical manifestation of PAOD includes the occurrence of intermittent claudication, rest pain and gangrene, and so on. In clinical practice, it is often divided into four grades based on clinical signs and symptoms of the patients and treated accordingly. Therefore accurate grading of the disease has important clinical value in the treatment and prognosis of the patients.The imaging methods play a very important role in the diagnosis of PAOD, including color Doppler ultrasound, DSA, CTA and MRA. For each method, there are relatively advantages and disadvantages.MRA technology has a long period of development and progress, from un-enhanced methods of TOF and PC to CE MRA, which spatial resolution and tissue resolution increased significantly. Therefore, CE MRA application is more and more in recent years, but whatever are its advantages and disadvantages, needs to be further study. Part I Feasibility of 3D DCE MRA in lower extremity arteries and the comparison of image quality between scanners of 1.5 T and 3.0 TPurposeTo study the feasibility of 3D DCE MRA in lower extremity arteries. To find the difference of image quality between scanners of 1.5 T and 3.0 T.Materials and MethodsThe subjects were the clinical patients who were suspected PAOD and underwent 3D DCE MRA and confirmed by DSA or surgery. 1) Group of 1.5T:Twenty-five cases, Siemens Sonata 1.5 T MR Scanner,3D DCE MRA with low dose bolus test. GD-DTPA was used as the contrast agent. 2) Group of 3.0T:Thirty-five cases, GE Signa Excite HD 3.0 T MR Scanner,3D DCE MRA with fluoro-trigger method. GD-DTPA was used as the contrast agent.Images of the arterial were obtained by subtracting the mask images from the images acquired after contrast agent injection.3D volumes were then reproduced using Maximum Intensity Projection (MIP) and Multi-Planar Reformation (MPR). The image quality was assessed by two experienced MR doctors blindly, and the agreement between two observers was assessed by the Kappa value. The image quality was compared between 1.5 T and 3.0 T.The statistic analysis was done with SPSS 17.0 and P<0.05 was considered as the level of with statistical significance.ResultsThe agreement between two observers was high in the pelvic segment and the calf segment in both groups (k=0.689,0.632 in 1.5 T group;k=0.643,0.727 in 3.0 T group). The agreement in the thigh segment was moderate (k=0.565 and 0.580). There was no statistical significance in the difference of image quality between the pelvic segment and the thigh segment (P=0.746 in 1.5T group; P=0.812 in 3.0T group). There was statistical significance in that between the pelvic and calf segment and between the thigh and calf segment (P=0.000 in both groups). There was no statistical significance in the difference of image quality between two groups in all three segments (P1=0.556, P2=0.795, P3=0.278). However, the scores in 3.0T group were a little higher than those in 1.5T group.Partâ…¡The vale of 3D DCE MRA in the classification of PAODPurposeTo study the clinical evaluation of 3D CE MRA in the classification of artery stenosis degree in PAOD.Materials and MethodsSixty patients who were suspected PAOD underwent 3D DCE MRA and DSA or surgery. Fifty-two cases of them performed DSA successfully, and 22 of them performed surgery, including 8 patients who failed in DSA.PAOD was classified into four degree by the clinical manifestation, and divided into five classes by the stenosis degree on image. The results of 3D DCE MRA were compared with clinical classification and the results of DSA/surgery on the level of patient and artery segment. The results of DSA/surgery were considered as the gold standard.ResultsOn the level of patients, there was high agreement between the results of 3D DCE MRA and the results of DSA/surgery. But there was difference between clinical classification and the results of DSA/surgery.On the level of artery segment, there was also high agreement between the results of 3D DCE MRA and the results of DSA/surgery, which was 96.92% (1289/1330) in common and 88.23%(120/136),86.41%(89/103),95.70%(89/93),98.44%(189/192) in each degree of stenosis, respectively. Meanwhile, there was a certain overestimate and underestimate rate in the evaluation of the degree of stenosis. Conclusion(1)As an advanced vascular imaging modality,3D DCE MRA is relatively simple, non-invasive, non-radioactive and non-toxic. The image quality of the lower extremity artery of 3D DCE MRA is high. The degree of peripheral arterial stenosis of PAOD patients can be evaluated by 3D DCE MRA, and imaging information for further treatment can be provide. Some patients maybe avoid the invasive inspection of DSA. It is of great value in the clinical application.(2)Scanners of 1.5 T and 3.0 T both can be used to 3D DCE MRA of the lower extremity artery. It is a little better on the image quality with 3.0T scanner than with 1.5T scanner, although there is no statistical significance.(3)In practice, there is something needs to be noted including:the time of delay, patient location, and breath holding.(4)Meanwhile, there is a certain degree of underestimate and overestimate rate in PAOD classification by 3D CE-MRA, which should be paid attention to in practice.