基于CT容积扫描的时间域最大强度投影评估干细胞移植治疗前后严重下肢缺血患者的小腿血供

Use of volumetric CT-based time-maximum intensity projection(t-MIP)to evaluate calf blood supply in critical lower limb ischemia before and after stem cell transplantation therapy

目的分析时间域最大强度投影(time maximum intensity projection,t-MIP)用于定量评估干细胞移植治疗前后严重下肢缺血患者的小腿血流状态的可行性和可重复性。方法前瞻性纳入了16例拟行单腿干细胞移植治疗的严重下肢缺血患者,行术前单时相计算机断层血管造影(single phase computed tomographic angiography,sCTA)、术前术后两次320排容积CT灌注(CT perfusion,CTP)扫描、踝肱指数(ankle-branchial index,ABI)测量及Wong-Baker FACES疼痛评分。t-MIP图像与sCTA图像上显示的血管质量差异用Mann-Whitney秩和检验分析。两名观察者分别独立测定术前、术后小腿的血管容积,应用组间一致性(intra-class correlation,ICC)分析两者的测定一致性,配对t检验用于检验干细胞移植治疗前后患者小腿的血流状态变化,Pearson相关性分析研究小腿CT血管容积和ABI的相关性。结果共评价16条小腿。t-MIP图像显示小腿血管的质量明显优于sCTA图像,包括血管CT值、信噪比(signal-to-noise ratio,SNR)、对比噪声比(contrast-to-noise ratio,CNR)(P<0.001)及主观评分(P<0.05);sCTA图像和t-MIP图像分别显示小腿侧支血管23支及45支,两者之间的差异具有统计学意义(P<0.05)。术后血管容积较术前增加(P<0.05),观察者间对术前、术后血管容积评估的一致性好,ICC值分别为0.897和0.906。术后ABI较术前增加(P<0.05),但术前、术后Wong-Baker FACES评分之间差异无统计学意义(P>0.05)。小腿CT血管容积与ABI之间未发现明显相关性(P>0.05)。结论t-MIP可以提升容积CT图像对血管的显示质量,通过计算小腿血管容积可以定量评估干细胞移植治疗前后严重下肢缺血患者的小腿血流状态。

Objective To investigate the feasibility and reproducibility of volumetric CT-based time maximum intensity projection(t-MIP)for quantitative assessment of calf blood flow in patients with severe lower limb ischemia before and after stem cell transplantation therapy.Methods Sixteen patients with severe lower extremity ischemia who underwent preoperative single-leg stem cell transplantation were prospectively enrolled.Single-phase computed tomographic angiography(sCTA)was performed before treatment;while 320-slice CT perfusion(CTP),ankle-branchial index(ABI)and Wong-Baker FACES pain score(WPS)were performed before and after treatment.Differences in the quality of blood vessel between the t-MIP and the sCTA images were compared by Mann-Whitney U test.Two observers independently measured the calf vessel volume in order to assess the blood flow status of the calf before and after stem cell transplantation.Intra-class correlation coefficient(ICC)was calculated between the two observers.The difference of calf blood flow between before and after therapy was tested by paired t test.Pearson correlation analysis was used to study the correlation between calf vessel volume and ABI.Results All the 16 calves were included in the analysis.The quality of the calf vessels shown on t-MIP was significantly better than that of the sCTA including vascular CT attenuation values,signal-to-noise ratio(SNR),contrast-to-noise ratio(CNR)(P<0.001)and subjective scores(P<0.05).The sCTA images showed 23 collateral vessels,while t-MIP images showed 45 collateral vessels,with the significant difference between them(P<0.05).The volume of blood vessels increased after operation(P<0.05),the consistency of the vessel volume assessment between the observers before and after treatment was excellent(ICC=0.897,0.906).ABI increased after operation(P<0.05).The difference between preoperative and postoperative WPS was not statistically significant(P>0.05).No significant correlation was found between the calf blood flow measured by vessel volume and ABI(P>0.05).Conclusion The t-MIP based on volumetric CT improves the display of blood vessels in the calf.The calf blood flow status of the patients with severe lower limb ischemia before and after stem cell transplantation can be quantitatively evaluated by calculating the vessel volume after CTP.