Late gadolinium uptake demonstrated with magnetic resonance in patients where automated PERFIT analysis of myocardial SPECT suggests irreversible perfusion defect

Abstract

Background: Myocardial perfusion single photon emission computed tomography (MPS) is frequently used as the reference method for the determination of myocardial infarct size. PERFIT(R) is a software utilizing a three-dimensional gender specific, averaged heart model for the automatic evaluation of myocardial perfusion. The purpose of this study was to compare the perfusion defect size on MPS, assessed with PERFIT, with the hyperenhanced volume assessed by late gadolinium enhancement magnetic resonance imaging (LGE) and to relate their effect on the wall motion score index (WMSI) assessed with cine magnetic resonance imaging (cine-MRI) and echocardiography (echo).

Methods: LGE was performed in 40 patients where clinical MPS showed an irreversible uptake reduction suggesting a myocardial scar. Infarct volume, extent and major coronary supply were compared between MPS and LGE as well as the relationship between infarct size from both methods and WMSI.

Results: MPS showed a slightly larger infarct volume than LGE (MPS 29.6 +/- 23.2 ml, LGE 22.1 +/- 16.9 ml, p = 0.01), while no significant difference was found in infarct extent (MPS 11.7 +/- 9.4%, LGE 13.0 +/- 9.6%). The correlation coefficients between methods in respect to infarct size and infarct extent were 0.71 and 0.63 respectively. WMSI determined with cine-MRI correlated moderately with infarct volume and infarct extent (cine-MRI vs MPS volume r = 0.71, extent r = 0.71, cine-MRI vs LGE volume r = 0.62, extent r = 0.60). Similar results were achieved when wall motion was determined with echo. Both MPS and LGE showed the same major coronary supply to the infarct area in a majority of patients, Kappa = 0.84.

Conclusion: MPS and LGE agree moderately in the determination of infarct size in both absolute and relative terms, although infarct volume is slightly larger with MPS. The correlation between WMSI and infarct size is moderate.

Figure 1

Infarct volume. Determination of infarct volume. LGE vs MPS (left). Regression line is shown. Corresponding Bland-Altman plot (right). Values are averaged from two observers.

Figure 2

Infarct extent. Determination of infarct extent. LGE vs MPS (left). Regression line is shown. Corresponding Bland-Altman plot (right). Values are averaged from two observers.

Figure 3

Subendocardial anteroseptal infarct where MPS and LGE agree. Upper row: Left – evaluation of the scar by MPS(Perfit) in short-axis view. Middle – corresponding image without automatic scar determination. Right – corresponding long axis view. Lower row: Left – manual evaluation of the scar on LGE image in short axis view. Middle – corresponding image without manual evaluation. Right – corresponding long axis view.

Figure 4

Discordance between MPS and LGE. MPS shows inferior infarct whereas LGE shows normal myocardium. For explanation see figure 3.

Figure 5

Wall motion score index vs infarct volume and extent, assessed with MPS. Wall motion score index determined by cine-MRI and echocardiography vs infarct volume assessed by MPS, in ml (left) and expressed as percent of myocardial volume (right). ▪ = WMSI(cine-MRI), ◦ = WMSI(echo). Dotted line expresses the regression line for WMSI(cine-MRI) and solid line the regression line for WMSI(echo).

Figure 6

Wall motion score index vs infarct volume and extent, assessed with LGE. Wall motion score index determined by cine-MRI and echocardiography vs infarct volume assessed by LGE, in ml (left) and expressed as percent of myocardial volume (right). ▪ = WMSI(cine-MRI), ◦ = WMSI(echo). Dotted line expresses the regression line for WMSI(cine-MRI) and solid line the regression line for WMSI(echo).