Prabhakar Rajiah MBBS, Presenter: Nothing to Disclose

Randolph Setser, Abstract Co-Author: Nothing to Disclose

Scott Daniel Flamm MD, Abstract Co-Author: Research grant, Koninklijke Philips Electronics NV Research grant, Siemens AG Medical Advisory Board, Vital Images, Inc

To determine the correlation between left ventricular outflow tract gradient in hypertrophic cardiomyopathy (HCM) patients as measured by MRI velocity-encoded phase-contrast imaging and echocardiography determined gradients. In addition, qualitative grading of outflow tract jets using two different MRI sequences were also compared with echocardiography.

62 consecutive patients (40 males, 22 females; mean age 51 years) with HCM underwent MRI examination at 1.5 T (Philips Achieva). Left ventricular outflow tract (LVOT) was assessed qualitatively with retrospectively gated segmented Steady-State Free-Precession (SSFP) and prospectively gated Gradient-recalled Echoplanar Imaging (EPI) sequences. After qualitative evaluation of flow acceleration jets in the outflow tract with these sequences, the peak resting gradient was measured using an inplane velocity-encoded (400 cm/sec) phase-contrast sequence and applying the Bernouli equation (∆P= 4v²), where V= maximal velocity in the LVOT. Gradient > 30 mm Hg was considered hemodynamically significant. The LVOT jet was graded qualitatively on a 1-4 point score based on percentage of systolic phases in which it was present (presence > 25 % of systolic phases was considered significant). These were compared with peak resting gradients acquired by echocardiography on the same day.

Image quality was excellent in all cases. There was only moderate agreement between the MRI and echocardiographic gradients (Kappa = 0.45, Standard error = 0.09, R² = 0.3), in spite of optimal planning for evaluation of jets. For qualitative grading of jets, the agreement between SSFP sequence and echocardiographic gradient was moderate (Kappa = 0.48, Standard error = 0.10, R²  = 0.2); in contrast there was substantial agreement between the jet seen in EPI sequence and echocardiographic gradient (Kappa = 0.71, Standard error = 0.09, R² = 0.4).

There is a good correlation between qualitative grading of LVOT jet in HCM patients using the EPI sequence and the echocardiographic grading, but only moderate agreement for qualitative LVOT grades and quantitative estimation of gradient.

Quantitative/qualitative estimation of LVOT gradient (an important prognostic indicator in HCM) by MRI adds to the already important role of MRI in HCM, further increasing its clinical utility.

Rajiah, P, Setser, R, Flamm, S, MRI Evaluation of Left Ventricular Outflow Tract Gradients in Hypertrophic Obstrutive Cardiomyopathy by Quantitative and Qualitative Techniques with Correlation to Echocardiography.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8012858.html