Planimetry of the Orifice Area in Aortic Valve Stenosis Using Phase-Contrast Cardiac Magnetic Resonance Imaging

Manual planimetry is a well-established method using transesophageal echocardiography (TEE) to assess the severity of aortic stenosis (AS). TEE, however, is a less than optimal approach in patients with calcified valves. Even when using cine-cardiac magnetic resonance (CMR), it is often difficult to evaluate the true border of the aortic orifice because of jet turbulence. With phase-contrast sequences of CMR, high flow signals at the aortic orifice can be clearly visualized, even in cases with severe calcification and jet turbulence. Therefore, the aims of the present study were to compare the utility of CMR using phase-contrast imaging with TEE and cine-CMR for the performance of planimetry of the aortic valve. The study cohort consisted of 30 consecutive patients with moderate or severe aortic valve stenosis documented by TEE who had undergone phase-contrast and cine-CMR for the evaluation of AS. Manual planimetry of the area of high flow signal was traced over the phase-contrast images at systolic peak, when the aortic valve is maximally opened. The results showed that the aortic valvular area (AVA) value derived from TEE correlated better with phase-contrast planimetry (r2 = 0.84, P < 0.05) than cine-mode planimetry (r2 = 0.57, P < 0.05). Bland-Altman plots indicated that the variation of measuring AVA was greater using the cine-mode method than the phase-contrast method. In conclusion, phase-contrast CMR offers a tool for evaluating the severity of aortic valve stenosis noninvasively. Phase-contrast CMR has the potential to become a routine clinical option as an alternative to TEE, at least in selected cases.