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. 2009 Nov;30(5):967-72.
doi: 10.1002/jmri.21953.

Shorter difference between myocardium and blood optimal inversion time suggests diffuse fibrosis in dilated cardiomyopathy

Yuchi Han  1 , Dana C Peters, Basem Dokhan, Warren J Manning
Affiliations

Shorter difference between myocardium and blood optimal inversion time suggests diffuse fibrosis in dilated cardiomyopathy

Yuchi Han et al. J Magn Reson Imaging. 2009 Nov.

Abstract

Purpose: To find evidence of diffuse fibrosis in dilated cardiomyopathy (DCM) patients by comparing measurements on clinical late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) studies between DCM and healthy subjects.

Materials and methods: LGE-CMR and the Look-Locker images from 20 DCM patients and 17 healthy controls were analyzed. Blood signal-to-noise ratio (SNR), myocardium SNR, and blood-to-myocardium contrast-to-noise ratio (CNR) were measured on the LGE-CMR images. The optimal inversion time (TI) to null blood and myocardium was determined on the Look-Locker images. The postcontrast T(1) was estimated using a phantom study that correlated optimal TI and heart rate to T(1).

Results: The blood SNR was lower, myocardium SNR was higher, and the blood-to-myocardium CNR was lower (6.6 +/- 0.7 vs. 10.3 +/- 0.9, P = 0.004) on DCM LGE-CMR images as compared to controls. The blood-myocardium optimal TI difference (DeltaTI) was lower (38 +/- 2 msec vs. 55 +/- 3 msec, P < 0.001) in DCM, and the estimated blood-myocardium T(1) difference (DeltaT(1)) (116 +/- 6 msec vs. 152 +/- 8 msec, P = 0.001) was also lower.

Conclusion: DCM patients have reduced blood-myocardium DeltaTI and DeltaT(1), and lower CNR as compared to controls, suggesting the presence of diffuse fibrosis. This may impact the interpretation of LGE data.

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Figures

Figure 1
Figure 1
Simulation of regrowth curves of blood (T1=350 ms), diffuse fibrosis (T1= 460 ms) and normal myocardium (T1= 510 ms) after a 180° inversion pulse. Zoomed view shows the difference in inversion times between blood, normal, and diffusely fibrosed myocardium (ΔTIN and ΔTID, respectively). MzN is proportional to the blood signal when normal myocardium is nulled. MzD is proportional to the blood signal when diffusely fibrosed myocardium is nulled.
Figure 2
Figure 2
SNR and CNR measurements on LGE-CMR images. A. An example of DCM LGE image with regions of interest (ROIs). B. An example of control with ROIs. C. Blood and myocardium SNR. D. Blood-to-myocardium CNR. Bd = blood, Avg = average, Avg-sep = average excluding septum, Sep = septum, Ant = anterior wall, Lat = lateral wall, Inf = inferior wall. * indicate p < 0.05, NS = not statistically significant.
Figure 3
Figure 3
Measurement of the optimal TI for phantom standards with known T1 values using the Look-Locker sequence, simulating heart rates of 50-90 beats per minute (bpm). At higher post-contrast T1 values and higher heart rates (90 bpm), the relationship between T1 and TI becomes non-linear. HR = heart rate.
Figure 4
Figure 4
The distribution of the difference of optimal TI of the blood and myocardium (ΔTI) in DCM and control subjects. The middle lines of the vertical boxes indicate the mean values and the top and bottom lines indicate ±SD.
See this image and copyright information in PMC

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