Tissue characterization of myocardial infarction using T1rho: influence of contrast dose and time of imaging after contrast administration.

PURPOSE: To determine whether contrast between acutely infarcted and normal myocardia in T1-rho-weighted cine TFE (T1rho-TFE) and delayed-enhancement (DE) images (measured using a metric percent enhancement (PE)) varied with the dose or time of imaging after contrast administration.

MATERIALS AND METHODS: Eighteen patients with acute myocardial infarction (AMI) were randomly divided into three groups according to the dose of gadoversetamide (0.1, 0.2, or 0.3 mmol/kg) administered. After contrast administration, T1rho-TFE images were acquired at five and 40 minutes, and DE images were acquired at 10 and 30 minutes.

RESULTS: For T1rho-TFE imaging the PE values at 40 minutes were 70+/-14, 98+/-14, and 105+/-41 at 0.1, 0.2, and 0.3 mmol/kg dose levels, which were significantly greater than the corresponding PEs at five minutes after contrast administration (44+/-12, 71+/-14, and 36+/-13). For DE and T1rho-TFE imaging the dose of contrast agent did not significantly affect the PE. However, with DE the PE tended to increase with the dose. At all dose levels, irreversible injury was more conspicuous in T1rho-TFE images acquired at 40 minutes than at five minutes after contrast.

CONCLUSION: In T1rho-TFE, acute infarction was more conspicuous in images acquired at a later time point, and the PE did not vary with the contrast dose.