7.0T MR T2* mapping与T2 mapping检测急性心肌梗死再灌注模型大鼠心肌内出血

目的 观察7.0T MR T2^* mapping与T2 mapping检测急性心肌梗死(AMI)再灌注模型大鼠心肌内出血(IMH)的图像质量及其价值。方法 以42只SD大鼠制备AMI再灌注模型,于其后2 d及7 d采集左心室7.0T MR T2^* mapping与T2 mapping,获得后处理T2^* map与T2 map图;之后处死大鼠,取心脏进行病理检查,评估IMH。观察IMH大鼠各序列原始图像的信噪比(SNR)、对比噪声比(CNR)、图像质量评分及T2^* map与T2 map图像的信号均一性。以病理结果为标准,分析2个序列图像检出IMH的效能。结果 造模后2 d (9只)和7 d (16只)后,共25只大鼠造模成功并检出IMH (IMH组),10只存在AMI但无IMH,6只无心肌梗死(无心肌梗死组),另1只在扫描过程中死亡;2 d和7 d IMH组心脏T2 mapping原始图像的SNR＞T2^* mapping原始图像(P均=0.001),而CNR差异均无统计学意义(P均＞0.05)。造模后2 d,IMH组心脏T2 mapping原始图像质量评分(3.90±0.30)高于T2^* mapping (3.80±0.40,t=3.67,P＜0.01);造模后7 d,T2 mapping原始图像质量评分(3.60±0.50)与T2^* mapping差异无统计学意义(3.50±0.50,t=1.65,P=0.10)。IMH组T2 map与T2^* map图像的出血心肌及远端心肌的变异系数(COV)差异均无统计学意义(P均＞0.05),提示信号均一性无明显差异。T2 mapping及T2^* mapping检出IMH的敏感度分别为88.00%(22/25)及96.00%(24/25)。结论 7.0T MR T2^* mapping图像信号均一性、SNR及图像质量略低于T2 mapping,二者CNR相当,均可用于检测AMI再灌注大鼠模型IMH。

7.0T MR T2* mapping and T2 mapping for detecting intramyocardial hemorrhage in acute myocardial infarction reperfusion rat models

Objective To observe imaging quality of 7.0T MR T2^* mapping and T2 mapping and the value for detecting intramyocardial hemorrhage(IMH) in acute myocardial infarction (AMI) reperfusion rat models. Methods AMI reperfusion models were established using 42 SD rats. 7.0T MR T2^* mapping and T2 mapping images of left ventricle were collected 2 days and 7 days later, respectively, and post-processing images of T2^* map and T2 map were obtained. Then the rats were sacrificed, the hearts were harvested, and pathological examinations were performed to evaluate IMH. The signal to noise (SNR), contrast to noise (CNR) and image quality score of raw images of 2 sequences in IMH rats were observed, so as the coefficient of variations (COV) of T2^* map and T2 map. Taken pathological results as the standards, the efficiency of 2 sequences for detecting IMH was analyzed. Results Totally 25 rats were successfully modeled with IMH (IMH group) 2 days (9 rats) and 7 days (16 rats) after modeling, while 10 rats had AMI but without IMH, and 6 rats had no myocardial infarction (NMI group). One rat died during MR scanning. Two and 7 days after modeling, in IMH group, SNR of original image of heart T2 mapping was higher than that of T2^* mapping (both P=0.001), while no significant difference of CNR was found (both P>0.05). Two days after modeling, in IMH group, the image quality score of original images of heart T2 mapping (3.90±0.30) was higher than that of T2^* mapping (3.80±0.40, t=3.67, P<0.01). Seven days after modeling, there was no significant difference of image quality score between T2 mapping and T2^* mapping original images in IMH group (3.60±0.50, 3.50±0.50, t=1.65, P=0.10). In IMH group, no significant difference of COV in bleeding myocardium nor remote myocardium was found between T2^* map and T2 map (both P>0.05). The sensitivity of T2 mapping and T2^* mapping for detecting IMH was 88.00%(22/25) and 96.00%(24/25), respectively. Conclusion The signal uniformity of 7.0T MR T2^* mapping was slightly lower that of T2 mapping, so as its SNR and image quality, while CNR of 7.0T MR T2^* mapping and T2 mapping were similar. Both T2^* mapping and T2 mapping could be used for detecting IMH in AMI reperfusion rat models.