Feasibility of Cardiovascular Magnetic Resonance to Assess the Orifice Area of Aortic Bioprostheses

Abstract

Background-Prosthetic orifice area, usually calculated by transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE), provides important information regarding the hemodynamic performance of aortic bioprostheses. However, both TTE and TEE have limitations; therefore accurate and reproducible determination of the orifice area often remains a challenge. The present study aimed to investigate the feasibility of cardiovascular magnetic resonance (CMR) to assess the orifice areas of aortic bioprostheses. Methods and Results-CMR planimetry of the orifice area was performed in 65 patients (43/22 stented/stentless prostheses; mean time since implantation, 3.1Ϯ2.8 years; mean orifice area [TTE], 1.70Ϯ0.43 cm 2 ; 62 normally functioning prostheses, 2 severe stenoses, and 1 severe regurgitation) in an imaging plane perpendicular to the transprosthetic flow using steady-state free-precession cine imaging under breath-hold conditions on a 1.5-T MR system. CMR results were compared with TTE (continuity equation, nϭ65) and TEE (planimetry, nϭ31). CMR planimetry was readily feasible in 80.0%; feasible with limitation in 15.4% because of stent, flow, and sternal wire artifacts; and impossible in 4.6% because of flow artifacts. Correlations of the orifice areas by CMR with TTE (rϭ0.82) and CMR with TEE (rϭ0.92) were significant. The average difference between the methods was Ϫ0.02Ϯ0.24 cm 2 (TTE) and 0.05Ϯ0.15 cm 2 (TEE). Agreement was present for stented and stentless devices and independent of orifice size. Intraobserver and interobserver variabilities of CMR planimetry were 6.7Ϯ5.4% and 11.5Ϯ7.8%. Conclusions-The assessment of aortic bioprostheses with normal orifice areas by CMR is technically feasible and provides orifice areas with a close correlation to echocardiography and low observer dependency. (Circ Cardiovasc Imaging. 2009;2:397-404.)

Bicuspid Aortic Valve Is Associated With Altered Wall Shear Stress in the Ascending Aorta

“…Slice positioning and imaging parameters were selected, as previously reported. 29,30 In subjects, in whom these valvular planes were not acquired, transthoracic echocardiography was used to assess valve morphology and function after international guidelines. 31 Aortic size measurements were obtained from axial SSFP imaging of the thorax, as described earlier.…”

Cardiac chamber quantification using magnetic resonance imaging at 7 Tesla—a pilot study

“…The matrix size and imaging parameters used at 1.5 T were deliberately chosen to reflect standard imaging parameters and protocols used in day-to-day clinical routine [28], while the imaging parameters used at 7 T were tailored for this field strength to push its limits.…”

In vitro assessment of heart valve bioprostheses by cardiovascular magnetic resonance: four-dimensional mapping of flow patterns and orifice area planimetry☆

“…CMR seems to be a suitable technique for this purpose. In vivo, the accuracy of CMR to assess the prosthetic orifice area has already been proven [2,3]. In vitro, the principal feasibility to assess orifice areas using CMR and a phantom model has already been shown in 2001 by our group [22].…”

“…Imaging parameters of the FGRE sequence were chosen as applied in vivo [2,3]: slice thickness, 5 mm; TR, 6.5 ms; TE, 3.6 ms; FA, 15; FOV, 340 Â 276 mm 2 ; matrix, 256 Â 208; bandwidth, 260 Hz/px; and 25 phases per R-R interval.…”

“…On the one hand, CMR using cine imaging has already been established as an accurate technique to assess the orifice area of bioprostheses implanted in aortic and mitral positions [2,3]. On the other hand, CMR with time-resolved three-dimensional flow measurements has been introduced to visualize the intravascular blood flow dynamics [4,5].…”