FSD-bSSFP非增强MRA下肢动脉病变诊断的初步探讨

Non-Contrast MRA with Flow-sensitive Dephasing Prepared Balance Steady-state Free Precession in Lower Extremity Arterial Diseases

目的探讨以血流敏感散相(flow-sensitive dephasing,FSD)为准备脉冲的平衡稳态自由进动序列(bSSFP)在下肢动脉病变中的诊断价值。资料与方法 42例糖尿病患者采用FSD-bSSFP序列非增强磁共振血管造影(NC-MRA)和对比增强磁共振血管造影(CE-MRA)行小腿部动脉扫描,将血管分为胫前动脉、胫后动脉和腓动脉3个节段。以CE-MRA作为参照标准,评价FSD-bSSFP上各血管的狭窄程度(分为0～4级),计算FSD-bSSFP各级血管狭窄程度的敏感性、特异性、阳性预测值、阴性预测值和诊断准确性。运用配对χ2检验分析两种检查方法诊断血管显著性狭窄(≥50%和闭塞)有无统计学差异,并采用Cohen’s kappa检验进行一致性分析。分析FSD-bSSFP在下肢动脉病变的应用价值。结果 42例中41例成功进行了FSD-bSSFP检查,获取243个动脉节段。FSD-bSS-FP对下肢动脉狭窄各级的(0～4级)敏感性分别为97.87%、98.13%、96.86%、94.93%、92.31%;特异性分别为95.10%、93.98%、94.23%、92.31%、84.77%;阳性预测值分别为96.50%、96.91%、98.40%、99.04%、68.57%;阴性预测值分别为97.00%、96.30%、89.09%、68.57%、99.04%;准确性分别为96.71%、96.71%、96.30%、94.65%、94.65%。FSD-bSSFP和CE-MRA对血管狭窄程度分级的总符合率为83.13%。两种检查方法对血管显著性狭窄的诊断差异无统计学意义(χ2=0.13,P>0.05),并且具有极好的一致性(k=0.93)。FSD-bSSFP的敏感性、特异性随下肢动脉血管狭窄的程度逐渐降低。结论 FSD-bSSFP序列能较准确地显示下肢动脉病变,可为肾功能不全或不能使用对比剂的患者提供一项可靠的下肢动脉病变的影像学检查方法。

Objective To discuss the value of FSD-bSSFP using balance steady-state free precession and flow-sensitive dephasing（FSD-bSSFP） in lower extremity arterial diseases.Materials and Methods Forty-two diabetic patients underwent FSD-bSSFP sequence and contrast-enhanced MRA（CE-MRA）examination in lower-extremity peripheral arteries.Three segments,including anterior tibial artery,posterior tibial artery and peroneal artery were included in the study.CE-MRA was regarded as the standard,Sensitivity,specificity,positive predictive value,negative predictive value and accuracy rate of each stenosis grade on FSD-bSSFP were calulated.Paired χ2 test was used to analyzed the difference between CE-MRA and FSD-bSSFP in diagnosis of significant stenosis.Cohen＇s kappa was used to assess agreement between two methods.Results Forty-one patients were successfully undergone FSD-bSSFP.A total of 243 arterial segments were obtained in the 41patients.Sensitivity,specificity,negative and positive predictive values and accuracy rate were calculated in FSD-bSSFP.Sensitivity of peripheral arterial stenosis（grade 0-4） were 97.87%,98.13%,96.86%,94.93%,92.31%;Specificity were 95.10%,93.98%,94.23%,92.31%,84.77%;positive predictive values were 96.50%,96.91%,98.40%,99.04%,68.57%;Negative predictive values were 97.00%,96.30%,89.09%,68.57%,99.04% and the accuracy rate were 96.71%,96.71%,96.30%,94.65%,94.65%.The total coincidence rate of FSD-bSSFP and CE-MRA was 83.13%.There was no significant difference between NC-MRA and CE-MRA in diagnosis of significant stenosis（χ2=0.13,P0.05）.The interrater reliability of the two methods for the diagnosis of arterial significant stenosis was very good（k value =0.93）.Spearman correlation analysis showed that sensitivity and specificity of FSD-bSSFP was significantly correlated with the extent of lower arterial stenoses.Conclusion FSD-bSSFP NC-MRA is a good method for depicting the lower extremity arterial diseases,which could be choosed for the patients with lower extremity arterial diseases who have renal insufficiency or who cannot use contrast media.