三种自由呼吸门控技术在肝脏MRI中的临床应用对比

Clinical comparison of three respiratory-trigger techniques in free-breathing liver magnetic resonance imaging

目的:比较一种新的调频连续波(FMCW)雷达触发技术与传统的膈肌导航触发技术和呼吸门控触发技术在自由呼吸肝脏MRI中的临床应用对比。方法:临床收集23例患有肝脏疾病的患者,同时使用调频连续波雷达触发技术(FT)、膈肌导航触发技术(NT)、呼吸门控触发技术(BT)在自由呼吸状态下行肝脏磁共振T_(2)WI和DWI,评估三种技术下各序列的图像质量和成像时间,测量和比较信噪比SNR_(病灶)、SNR_(肝)、对比度噪声比CNR及ADC值。结果:NT的T_(2)WI图像质量优于FT和BT并且扫描时间最长(N=23,P<0.05),三者的DWI图像质量无差异。三者的T_(2)WI和DWI中SNR_(肝)相似。FT的DWI_(b50)中SNR_(病灶)(705.13±434.80)和CNR(504.41±400.69)高于NT(SNR_(病灶):639.41±407.98,CNR:420.64±416.61)和BT(SNR_(病灶):651.83±401.16,CNR:429.24±404.11),差异均有统计学意义(P<0.05)。三者在肝实质、病灶的ADC值差异无统计学意义。结论:FT在DWI_(b50)中有较高的SNR_(病灶)和CNR,可替代BT,具有更为广泛的临床应用前景;NT的T_(2)WI图像质量最好,扫描时间最长,适用于呼吸不稳定的患者。

Objective:The aim of this study is to compare a novel respiratory frequency-modulated continuous-wave radar-trigger(FT) technique with conventional navigator-trigger(NT) and respiratory breath-gated trigger(BT) techniques for patients in free-breathing liver magnetic resonance imaging.Methods:In this study,23 patients with known or suspected liver diseases were enrolled.Six sequences(T_(2)WI and DWI with FT,NT,and BT techniques) were performed in each subject.The acquisition time and image quality scores of them were assessed.The liver and lesion signal-to-noise ratio(SNR),the lesion-to-liver contrast-to-noise ratio(CNR),as well as the apparent diffusion coefficient(ADC) value were quantitatively calculated.Results:NT was superior to other techniques for image quality on T_(2)WI with the longest acquisition time(n=23,P<0.05),conversely,little difference was found on DWI in qualitative assessment.The mean SNR of the liver on T_(2)WI and DWI with FT,NT,and BT techniques was similar.FT performed better in terms of higher lesion SNR(705.13±434.80) and higher CNR(504.41±400.69) on DWI at b50 compared with NT(SNR:639.41±407.98;CNR:420.64±416.61) and BT(SNR:651.83±401.16;CNR:429.24±404.11)(n=28,P<0.05).The mean ADC values of the liver and lesion with different techniques showed non-significant difference.Conclusion:FT is superior to BT and NT techniques in terms of higher lesion SNR and CNR on DWI at b50.FT can replace BT technique and has a wider clinical application prospect.NT performed mostly better for image quality on T_(2)WI,followed by FT and BT.Meanwhile it takes the longest acquisition time,so it is suitable for patient with unstable breathing.