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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 investigate the diagnostic value of balanced steady-state free precession sequence (bSSFP) with pulsed-sensitive dephasing (FSD) as a preparation pulse in the diagnosis of lower extremity arterial disease. Materials and Methods Forty-two diabetic patients underwent CT-bSSFP non-contrast enhanced MR angiography (NC-MRA) and contrast-enhanced MR angiography (CE-MRA) for calf arteries. The vessels were divided into anterior tibial artery Posterior tibial artery and peroneal artery 3 segments. The CE-MRA was used as a reference standard to evaluate the degree of stenosis of each vessel on the FSD-bSSFP (range from 0 to 4). The sensitivity, specificity, positive predictive value and negative predictive value of FSD-bSSFP at all levels were calculated And diagnostic accuracy. Paired χ2 test analysis of the two methods of diagnosis of significant vascular stenosis (≥ 50% and occlusion) with or without significant differences, and Cohen’s kappa test consistency analysis. The value of FSD-bSSFP in arterial disease of lower extremity was analyzed. Results Forty-one of 42 patients underwent FSD-bSSFP and 243 arterial segments were obtained. The sensitivity of FSD-bSS-FP to grade 0-4 of lower extremity arterial stenosis was 97.87%, 98.13%, 96.86%, 94.93% and 92.31% respectively. The specificity of FSD-bSS-FP was 95.10%, 93.98% and 94.23% The positive predictive values were 96.50%, 96.91%, 98.40%, 99.04%, 68.57%, respectively. The negative predictive values were 97.00%, 96.30%, 89.09%, 68.57%, 99.04% 96.71%, 96.71%, 96.30%, 94.65%, 94.65%. The total compliance rate of FSD-bSSFP and CE-MRA for grade of vascular stenosis was 83.13%. There was no significant difference between the two methods in the diagnosis of significant vascular stenosis (χ2 = 0.13, P> 0.05), with excellent agreement (k = 0.93). The sensitivity and specificity of FSD-bSSFP gradually decrease with the degree of arterial stenosis of lower limbs. Conclusions The FSD-bSSFP sequence can show arterial lesions of the lower extremities more accurately. It can provide a reliable imaging method of lower extremity arterial disease in patients with renal insufficiency or contrast agent.