零点充填技术提高增强磁共振血管成像内径测量准确性的模型研究

Phantoms study:zero-filled interpolation technique improves the accuracy of vessel diameter measurement in contrast-enhanced MR angiography

目的:探讨零点充填技术提高增强磁共振血管成像血管内径测量准确性的价值。方法:应用一个仿真血管模型,高空间分辨率序列使用零点充填技术。宽度中点法确定血管边缘后计算血管内径,两种序列对不同大小仿真血管内径测量结果的比较采用配对t检验。结果:两种序列的内径测量结果均比真实值高,但高空间分辨率序列的高估程度小,对于中等大小的血管,高空间分辨率序列与常规序列测量结果的差别无统计学意义(P>0.05),而对于小血管则两者差别有统计学意义(P<0.05和P<0.01)。结论:增强磁共振血管成像中有必要应用零点充填技术,该技术的应用能够提高小血管腔内直径测量的准确性。

Objective： To evaluate zero-filled interpolation （ZIP） technique for improving the accuracy of vessel diameter measurement in contrast-enhanced MRA（CE-MRA） by comparing zero-filled high-spatial-resolution CE-MRA with conventional CE-MRA in anatomical phantoms. Methods： Phantoms of arteries were made with different lumen diameter. A head coil was utilized. The parameters of fast spoiled gradient recalled （FSPGR） pulse sequence were： flip angle 30°,TR 6ms, TE 1.4ms, bandwidth 31.25kHz, slice thickness 1.2mm, matrix 256 × 256. The sequence parameters were kept constant for the studies, whereas ZIP technique was used for high-spatial-resolution CE-MRA. MR maximum intensity projection （MIP） images were created. Vessel edge was determined using full width at half maximum（FWHM） for lumen diameter calculation and calculated results were compared by T test. Results： Comparing with the actual lumen diameter, all FWHM results of lumen measurements were overestimated. But this overestimation was reduced on zero-filled high-spatial-resolution CE-MRA. For medium-sized arteries（8.00mm, 5.50mm, 3.50mm）, the effect of ZIP technique reducing overestimation was small（ P 〉0.05）,but this effect was significant for little-sized arteries （2.30mm, 1.50mm ）. Contusion： It is necessary to utilize ZIP for CE-MRA. For little-sized arteries, ZIP technique can improve the accuracy of vessel diameter measurement, and utilization of ZIP technique is significant for calculating the degree of stenosis of arteries with severe stenosis.