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- Open Access
Papillary muscle involvement in acute and chronic myocardial infarction: an MRI study using multi-contrast delayed enhancement pulse sequence
© Yang et al; licensee BioMed Central Ltd. 2009
- Published: 28 January 2009
- Mitral Regurgitation
- Papillary Muscle
- Blood Pool
- Wall Motion Abnormality
- Mitral Valve Regurgitation
The papillary muscle (PM) is an integral component of the mitral valve apparatus. Acute or chronic myocardial infarction (MI) with PM ischemia is a primary factor leading to the occurrence of mitral regurgitation, with associated substantial morbidity and mortality [1, 2]. PM-MI is also a source of ventricular arrhythmia in these patients . Although DE-MRI using IR-FGRE can detect PM-MI, its accuracy is primarily limited by poor contrast between left ventricular (LV) blood pool and infarcted myocardium.
We hypothesize that multi-contrast delayed enhancement (MCDE) imaging will improve the identification of PM-MI in patients with acute and chronic MI, compared to conventional IR-FGRE imaging.
Cardiac DE-MRI studies using both MCDE and IR-FGRE in patients with MI were reviewed. Twenty-three patients (21 males, 2 females, average age of 62 ± 10 years old; 5 acute MI within 7 days, 18 chronic MI > 4 weeks) met the diagnostic criteria of PM-MI, as outlined below. All studies were performed on a 1.5 T GE Signa HDx system (GE Healthcare, Milwaukee, WI), which included a short-axis oblique (SAO) and two or four chamber SSFP studies. Both IR-FGRE and MCDE covering the whole LV in SAO were performed 10–20 minutes after double-dose bolus injection of Gd-DTPA. For IR-FGRE, the TI varied from 200 to 300 ms, depending on the null point of healthy myocardium. For MCDE, a segmented SSFP readout is used following an inversion pulse, providing 20 cardiac-phase-resolved images at varying effective TIs . The in-plane resolution was 1.5 × 1.5 mm for both techniques.
PM-MI was considered if the following criteria were satisfied in the IR-FGRE or MCDE images: (1) the increased signal intensity of PM was similar to that of adjacent hyper-enhanced infarct segments; (2) the hyper-enhanced PM region was limited to the PM area defined by pre-contrast SSFP. The contrast between blood pool and hyper-enhanced LV infarct was rated as excellent (3), good (2) or fair (1) based on their differentiation.
MCDE imaging provides better contrast between blood pool and infarcted myocardium, thus improving the determination of PM-MI that may help identify patients in whom the significant mitral regurgitation may affect morbidity and mortality.
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