Laissy Jean-Pierre, Messin Benoît, Varenne Olivier, Iung Bernard, Karila-Cohen Daniel, Schouman-Claeys Elisabeth, Steg P Gabriel
Departments of Radiology, Hôpital Bichat, Paris, France.
Chest. 2002 Nov;122(5):1638-48. doi: 10.1378/chest.122.5.1638.
To explore the diagnostic performance of MRI for the diagnosis of acute myocarditis, using a comprehensive imaging approach.
Twenty patients with myocarditis and 7 age-matched and gender-matched control subjects underwent comprehensive MRI. Magnetic resonance (MR) examinations included axial T2-weighted sequences, precontrast and postcontrast ECG-gated T1-weighted sequences in axial and short heart axis, cine-MRI, and serial dynamic turbo fast low-angle shot (turboFLASH) acquisitions in the short axis following Gd injection for a period of 2 min. Precontrast and postcontrast images were postprocessed using subtraction. Two observers read all images qualitatively and quantitatively. Myocardial enhancement was compared between patients and control subjects.
Myocardial involvement was focal in 6 patients examined within 1 week from clinical onset, and diffuse in the remaining 14 patients examined later.
Qualitatively, contrast-enhanced T1-weighted subtracted images had 100% sensitivity and specificity for myocardial involvement. Postcontrast T1-weighted images were able to discriminate the early phase (nodular enhancement) from the later phase of myocarditis (diffuse enhancement). Quantitatively, myocardial enhancement was 56% +/- 3.2% in patients, vs 29% +/- 3.1% in control subjects using T1-weighted MRI (p < 0.0001). Serial turboFLASH images displayed greater myocardial enhancement between 25 s and 120 s in patients than in control subjects (p < 0.0001); however, there was marked enhancement of skeletal muscles in both early and late stages of myocarditis compared to control subjects (p < 0.0001).
On the basis of subtracted cardiac-gated T1-weighted images and serial postinjection turboFLASH images, our study shows that myocarditis is largely, at least in the early stages, a focal process in the myocardium. It also provides evidence of transient skeletal muscle involvement, which may actually be useful for diagnosis.
采用综合成像方法探讨MRI对急性心肌炎的诊断效能。
20例心肌炎患者和7例年龄及性别匹配的对照受试者接受了综合MRI检查。磁共振（MR）检查包括轴位T2加权序列、轴位和短轴位的对比剂注射前及注射后心电图门控T1加权序列、电影MRI，以及注射钆后短轴位连续动态快速低角度激发（turboFLASH）采集2分钟。对比剂注射前和注射后的图像采用减法进行后处理。两名观察者对所有图像进行定性和定量分析。比较患者和对照受试者的心肌强化情况。
6例在临床发病1周内接受检查的患者心肌受累为局灶性，其余14例较晚接受检查的患者心肌受累为弥漫性。
定性分析，对比增强T1加权减影图像对心肌受累的敏感性和特异性均为100%。对比剂注射后T1加权图像能够区分心肌炎的早期阶段（结节状强化）和后期阶段（弥漫性强化）。定量分析，使用T1加权MRI，患者的心肌强化为56%±3.2%，对照受试者为29%±3.1%（p<0.0001）。连续turboFLASH图像显示，患者在25秒至120秒之间的心肌强化高于对照受试者（p<0.0001）；然而，与对照受试者相比，心肌炎的早期和晚期骨骼肌均有明显强化（p<0.0001）。
基于心脏门控T1加权减影图像和注射后连续turboFLASH图像，我们的研究表明，心肌炎在很大程度上，至少在早期阶段，是心肌的局灶性病变。它还提供了骨骼肌短暂受累的证据，这实际上可能有助于诊断。
