Abstract
Purpose: Unlike echocardiography which can quantify both LV filling and ejection, cine steady state free precession sequence (SSFP)-despite its high intrinsic signal and contrast to noise ratio, accuracy and precision of volume measurements-, is mostly relegated to quantifying LV ejection. The steady-state requirement typically constrains SSFP sequence to a breathhold (and limited temporal resolution). We describe: (a) free breathing cine SSFP approach that meets the SS requirement allowing high frame rate acquisition, (b) two MRI indices based on time-LV volume (TV) change during filling and compare against echocardiagraphic diastolic index (E/A ratio), and (c) evaluate the effect of temporal resolution on: LV volumes; ejection and filling rates; and normalized indices of systolic and diastolic function. Methods: A stack of contiguous LV short axis slices at high temporal resolution (τ=15 ms) was acquired using an in-house respiratory-triggered (RT), SS prepared, cardiac gated, free-breathing cine SSFP sequence (TR/TE/flip: 3.2 ms/1.5 ms/55°). All 24 study subjects provided written informed consent per IRB requirements. Subjects underwent both echo and MRI in one imaging session. From the expert-drawn contours, TV curve, and its derivative (dV/dt) were generated and these curves were downsampled to rates at 2τ,3τ,and 4τ. From TV and dV/dt curves during the early filling period (EFP) and late filling periods (LFP), volume based (VEFP/VLFP) and rate based (REFP/RLFP) diastolic indices were respectively defined, and calculated for each temporal resolution. Results: VEFP/VLFP and REFP/RLFP correlated well with E/Aecho. As temporal resolution declined from τ to 3τ, absolute percentage errors were: LV chamber volumes 20%.. Conclusion: By incorporating SS prep, RT can be used to obtain high frame rate cine SSFP sequence that can evaluate both LV systolic and diastolic function. Temporal resolution of cine SSFP is a key determinant of error in rate based diastolic indices. Research was partly supported by funding from Philips Healthcare.
Published Version
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