Diastolic function imaging: a comparison of real-time phase contrast magnetic resonance (CMR) imaging with segmented phase contrast CMR and Doppler echocardiography
Journal of Cardiovascular Magnetic Resonance volume 14, Article number: W21 (2012)
CMR measurement of mitral inflow velocities for the assessment of diastolic function is often infeasible in patients with dyspnea - patients who may benefit the most - due to their inability to breath-hold. Although real-time phase contrast (RT-PC) imaging may overcome this limitation, it has not been systematically evaluated. The objective of this study was to assess the accuracy of RT-PC for the measurement of mitral inflow velocities against segmented PC CMR and Doppler echocardiography.
37 healthy volunteers (aged 28 ± 10 years, 20 males) had echo and CMR studies within a week. Early (E) and late (A) mitral inflow velocities were measured by echo, segmented, and RT-PC CMR (Figure). The E and A velocities were obtained by averaging data from 2 heart beats by RT-PC and 3 heart beats by echo. RT-PC parameters were: TR/TE = 14.0ms/2.3ms, water excitation flip angle=25○,10mm slice, 90 x128 matrix, EPI factor=15, TSENSE rate=3, and VENC=150cm/s. Shared velocity encoding was used to achieve an effective temporal resolution of 28ms, but true temporal resolution was 56ms. Retro-gated segmented PC acquisition parameters: TR/TE = 4.5/1.9ms, 10mm slice, 100 x 192 matrix, TSENSE rate=3, VENC=150cm/s, true temporal resolution 36ms. E and A velocities, and E/A ratios between RT-PC and segmented PC CMR or Doppler echocardiography were compared using paired t-tests. Agreement between the techniques was assessed using concordance correlation coefficients and Bland-Altman analysis.
Mean E velocities by echo, segmented, and RT-PC CMR were 75 ± 15 cm/s, 77 ± 12 cm/s, and 73 ± 12cm/s , respectively. The RT-PC measurements were not different from echo (p=0.3), but were less than segmented PC CMR (p=0.04). The A velocities (38 ± 12 cm/s, 38 ± 11 cm/s, 35 ± 12 cm/s, respectively) were not different between RT-PC CMR and echo or segmented CMR (p=0.3 for both). There was also no difference in the E/A ratios (2.2 ± 0.6, 2.2 ± 0.7, and 2.2 ± 0.9, respectively; p =0.6 for both). There was moderate concordance between RT-PC CMR and segmented CMR and Echo for E, A and E/A ratio (Table 1). Although, the bias in measurement between RT-PC CMR and echo or segmented CMR was small, the LOA was wide.
We demonstrate for the first time the use of RT-PC imaging to measure mitral E and A velocities. There was modest agreement between RT-PC CMR and echo and segmented PC CMR. Further refinements of the RT-PC sequences are necessary; however, the use of RT-PC imaging provides an opportunity for wider application in patients who have difficulty with breath holding or arrhythmias.
National Institute of Health (NIH, R01).
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Thavendiranathan, P., Bender, J.A., Dickerson, J. et al. Diastolic function imaging: a comparison of real-time phase contrast magnetic resonance (CMR) imaging with segmented phase contrast CMR and Doppler echocardiography. J Cardiovasc Magn Reson 14 (Suppl 1), W21 (2012). https://doi.org/10.1186/1532-429X-14-S1-W21