MRI of acute myocarditis: a comprehensive approach based on various imaging sequences.
OBJECTIVE
To explore the diagnostic performance of MRI for the diagnosis of acute myocarditis, using a comprehensive imaging approach.


METHODS
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.


METHODS
Myocardial involvement was focal in 6 patients examined within 1 week from clinical onset, and diffuse in the remaining 14 patients examined later.


RESULTS
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).


CONCLUSIONS
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.
Laissy
Jean-Pierre
JP
Departments of Radiology, Hôpital Bichat, Paris, France. jean-pierre.laissy@bch.ap-hop-paris.fr
Messin
Benoît
B
Varenne
Olivier
O
Iung
Bernard
B
Karila-Cohen
Daniel
D
Schouman-Claeys
Elisabeth
E
Steg
P Gabriel
PG
D000208:Acute Disease; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009205:Myocarditis / Q000473:pathology*; D011446:Prospective Studies