BACKGROUND The reliable quantification of myocardial blood flow (MBF) with MRI, necessitates the correction of errors in arterial input function (AIF) caused by the T1 saturation effect. The aim of this study was to compare MBF determined by a traditional dual bolus method against a modified dual bolus approach and to evaluate both methods against PET in a porcine model of myocardial ischemia. METHODS Local myocardial ischemia was induced in five pigs, which were subsequently examined with contrast enhanced MRI (gadoteric acid) and PET (O-15 water). In the determination of MBF, the initial high concentration AIF was corrected using the ratio of low and high contrast AIF areas, normalized according to the corresponding heart rates. MBF was determined from the MRI, during stress and at rest, using the dual bolus and the modified dual bolus methods in 24 segments of the myocardium (total of 240 segments, five pigs in stress and rest). Due to image artifacts and technical problems 53% of the segments had to be rejected from further analyses. These two estimates were later compared against respective rest and stress PET-based MBF measurements. RESULTS Values of MBF were determined for 112/240 regions. Correlations for MBF between the modified dual bolus method and PET was rs = 0.84, and between the traditional dual bolus method and PET rs = 0.79. The intraclass correlation was very good (ICC = 0.85) between the modified dual bolus method and PET, but poor between the traditional dual bolus method and PET (ICC = 0.07). CONCLUSIONS The modified dual bolus method showed a better agreement with PET than the traditional dual bolus method. The modified dual bolus method was found to be more reliable than the traditional dual bolus method, especially when there was variation in the heart rate. However, the difference between the MBF values estimated with either of the two MRI-based dual-bolus methods and those estimated with the gold-standard PET method were statistically significant.

中文翻译：

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改进的双重大剂量MRI对猪心肌灌注的定量分析-前瞻性研究，以PET为参考。

背景技术利用MRI对心肌血流（MBF）的可靠定量，需要校正由T1饱和作用引起的动脉输入功能（AIF）的误差。这项研究的目的是比较传统的双重推注方法与改良的双重推注方法测定的MBF，并评估在猪心肌缺血模型中针对PET的两种方法。方法在5只猪中诱发局部心肌缺血，随后用对比增强MRI（g酸）和PET（O-15水）进行检查。在MBF的测定中，使用高和低对比度AIF区域的比例校正初始高浓度AIF，并根据相应的心率进行归一化。MBF是根据MRI在压力和静止状态下确定的，在心肌的24个部分中使用双重推注和改进的双重推注方法（总共240个区段，五只猪处于压力和休息状态）。由于图像伪影和技术问题，53％的片段不得不从进一步的分析中剔除。随后将这两个估计值与基于静息压力和基于压力PET的MBF测量值进行比较。结果确定了112/240个区域的MBF值。改良的双推注法与PET之间的MBF相关系数为rs = 0.84，而传统的双推注法与PET之间的相关系数为rs = 0.79。改良的双重推注方法和PET之间的类内相关性非常好（ICC = 0.85），而传统的双重推注方法和PET之间的类内相关性很差（ICC = 0.07）。结论改良的双重推注方法与PET相比，传统的双重推注方法具有更好的一致性。发现改进的双重推注方法比传统的双重推注方法更可靠，尤其是在心率变化的情况下。但是，两种基于MRI的双重推注方法之一估计的MBF值与金标准PET方法估计的MBF值之间的差异在统计学上是显着的。