Hamer Okka W, Finkenzeller Thomas, Borisch Ingitha, Paetzel Christian, Zorger Niels, Feuerbach Stefan, Nitz Wolfgang
Department of Diagnostic Radiology, University Hospital of Regensburg, Franz-Josef-Strauss-Allee 11, 93042 Regensburg, Germany.
AJR Am J Roentgenol. 2005 Nov;185(5):1282-8. doi: 10.2214/AJR.04.1389.
Our study was a prospective in vivo study to evaluate whether MR angiography is suitable for assessing stent patency and grading in-stent stenoses and to examine whether the accuracy of MR angiography changes with time after stent implantation.
In a prospective study, 34 iliac stenoses in 27 patients were treated by implantation of 35 nitinol stents. MR angiography was performed immediately after stent placement for 32 stents, and both digital subtraction angiography (DSA) and MR angiography were repeated at the 6-month follow-up for 23 stents. Three blinded observers assessed stent patency and the degree of in-stent stenoses on MR angiography and DSA (the standard of reference) images. The difference between the observers' grading of stenoses on DSA and on MR angiography was determined. Statistical analysis was performed using the Student's t test for paired samples.
Stent patency was assessed correctly for all stents and both sets of MR angiography images. Evaluation of DSA 1 images (obtained at end of implantation procedure) revealed that 96.9% of in-stent stenoses were less than 50%. On DSA 2 images (obtained at follow-up), 95.7% of in-stent stenoses were graded as less than 50%. The difference between grading of stenoses on DSA and MR angiography images was 15.0% +/- 16.0% (minimum, 0.0%; maximum, 63.3%) for DSA 1 versus MR angiography 1 (statistically significant, p = 0.037) and 9.8% +/- 13.5% (minimum, 0.0%; maximum, 63.3%) for MR angiography 2 versus DSA 2 (not statistically significant, p = 0.355).
Patency was correctly assessed for all stents on MR angiography. The quality of MR angiography regarding characterization of in-stent stenoses improved with time after stent placement. However, discrepancies of more than 60% between grading of lumen narrowing on DSA and MR angiography images occurred even at the 6-month follow-up. Thus, MR angiography is not yet a reliable technique for characterization of in-stent stenoses.
我们的研究是一项前瞻性体内研究，旨在评估磁共振血管造影（MR angiography）是否适用于评估支架通畅情况及对支架内狭窄进行分级，并研究MR血管造影的准确性在支架植入后是否随时间变化。
在一项前瞻性研究中，27例患者的34处髂动脉狭窄接受了35枚镍钛合金支架植入治疗。32枚支架在植入后立即进行了MR血管造影，23枚支架在6个月随访时重复进行了数字减影血管造影（DSA）和MR血管造影。三位不知情的观察者对MR血管造影和DSA（参考标准）图像上的支架通畅情况及支架内狭窄程度进行评估。确定观察者在DSA和MR血管造影上对狭窄分级的差异。使用配对样本的学生t检验进行统计分析。
所有支架及两组MR血管造影图像的支架通畅情况均得到正确评估。对DSA 1图像（在植入手术结束时获得）的评估显示，96.9%的支架内狭窄小于50%。在DSA 2图像（随访时获得）上，95.7%的支架内狭窄分级为小于50%。DSA 1与MR血管造影1图像上狭窄分级的差异为15.0%±16.0%（最小值0.0%；最大值63.3%）（具有统计学意义，p = 0.037），MR血管造影2与DSA 2图像上的差异为9.8%±13.5%（最小值0.0%；最大值63.3%）（无统计学意义，p = 0.355）。
MR血管造影对所有支架的通畅情况评估正确。支架植入后，MR血管造影在支架内狭窄特征描述方面的质量随时间有所改善。然而，即使在6个月随访时，DSA和MR血管造影图像上管腔狭窄分级之间仍存在超过60%的差异。因此，MR血管造影尚未成为一种可靠的支架内狭窄特征描述技术。
