Purpose: Late enhancement magnetic resonance imaging (MRI) was compared with thallium-201 rest-redistribution single photon emission computed tomography (SPECT) in patients with reduced left ventricular (LV) function and prior myocardial infarction (MI).
Background: Hyperenhancement on contrast cardiac MRI using gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) has been reported to identify nonviable myocardium. Comparisons of MRI and thallium-201 SPECT have recently been reported. This study focuses on the comparison of these modalities specifically in patients with ischemic heart failure, where viability determination is most clinically relevant.
Methods: Fifteen patients with LV dysfunction and prior MI [mean ejection fraction (EF) 35 +/- 11%] underwent thallium-201 rest-redistribution scintigraphy and contrast MRI on separate days. Each short axis slice was divided into six 60-degree segments, and correlations between MRI and scintigraphy were made on viability detection for each segment. For SPECT, the mean uptake score was calculated from the average of all percent relative activity values throughout each segment. Areas with < 50% of maximal thallium uptake were considered nonviable. On MRI, regions with increased signal intensity after an injection of 0.1 mmol/kg Gd-DPTA were considered nonviable.
Results: A total of 558 segments were analyzed. Overall, there was a strong inverse relationship between the area of hyperenhancement on MRI and diminished thallium-201 uptake on SPECT (r = -0.51, P < 0.001). There was a significant correlation between the imaging methods for each individual segment, except for the inferior-septal segment (r = -0.38, P < 0.08).
Conclusions: In patients with LV dysfunction and prior MI, our data suggest MRI hyperenhancement significantly correlates with myocardial nonviability by thallium-201 SPECT. Correlations were weaker in the inferior-septal region, which may be due to SPECT attenuation artifact.