Quantification of aortic valve stenosis: head-to-head comparison of 64-slice spiral computed tomography with transesophageal and transthoracic echocardiography and cardiac catheterization.

OBJECTIVES: We sought to evaluate the accuracy of multislice computed tomography (MSCT) with 64 detector rows for determination of the aortic valve area (AVA) compared with transesophageal and transthoracic echocardiography (TEE and TTE) and cardiac catheterization (CATH). MATERIALS AND METHODS: MSCT, TEE, TTE, and CATH were performed in 36 patients with aortic valve stenosis. AVA was determined by planimetry on MSCT and TEE and calculated using the continuity equation on Doppler TTE and the Gorlin formula on CATH. RESULTS: The mean AVA on MSCT (0.88 +/- 0.39 cm2) was not significantly different from TEE (0.94 +/- 0.41 cm2; P > 0.05) but significantly larger than TTE (0.74 +/- 0.28 cm2; P < 0.001) and CATH (0.75 +/- 0.31 cm2; P < 0.001). A good correlation with acceptable limits of agreement was found between MSCT and TTE (r = 0.91, limits +/-0.35 cm2) and between MSCT and CATH (r = 0.91, limits +/-0.32 cm2). An inferior correlation with wider limits of agreement was found between MSCT and TEE (r = 0.82, limits +/-0.48 cm2), but this applied also between TEE and TTE (r = 0.79, limits +/-0.51 cm2) and between TEE and CATH (r = 0.78, limits +/-0.52 cm2). CONCLUSIONS: AVA determined by MSCT correlated well with TTE and CATH, but a systematic difference must be taken into account when using MSCT findings for therapeutic decision-making. Validation against both TTE and CATH revealed a superior correlation and narrower limits of agreement for MSCT than for TEE suggesting that AVA planimetry with MSCT is more reliable than with TEE.

Grading of aortic valve stenosis at 64-slice spiral computed tomography: comparison with transthoracic echocardiography and calibration against cardiac catheterization.

PURPOSE: We sought to determine the accuracy of multislice spiral computed tomography (MSCT) for assessing of aortic valve stenosis and to establish threshold values of the planimetric aortic valve orifice area (AVA) that best separate between different grades of stenosis severity. MATERIALS AND METHODS: A total of 202 patients (among them 160 patients with aortic valve stenosis) underwent MSCT, transthoracic echocardiography (TTE) and cardiac catheterization (CATH). Planimetric AVA measurements at MSCT were compared with calculations based on Doppler flow velocity measurements by TTE (using the continuity equation) and pressure gradient measurements by CATH (using the Gorlin formula). RESULTS: Series of AVA measurements correlated well between MSCT and TTE (r = 0.86) and between MSCT and CATH (r = 0.90). However, AVA at MSCT (0.98 +/- 0.47 cm) was significantly larger than AVA at TTE (0.81 +/- 0.36 cm; P < 0.05) and CATH (0.80 +/- 0.39 cm; P < 0.05). For severity grades 0 through IV the AVAs at MSCT were 2.69 +/- 0.75, 1.86 +/- 0.30, 1.48 +/- 0.17, 0.95 +/- 0.20, and 0.68 +/- 0.20 cm, respectively. For separating, the 5 severity grades optimal thresholds at MSCT were 2.1, 1.6, 1.2, and 0.9 cm. Using these adjusted thresholds there was perfect agreement in classification between MSCT and CATH in 156 (77%), but a mismatch by 1 grade in 43 (21.5%) and 2 grades in 3 (1.5%) patients (kappaw = 0.86). CONCLUSION: Planimetric AVA measurements on MSCT allows for an accurate grading of aortic valve stenosis severity. However, AVA measurements on MSCT are usually larger than measurements on TTE and CATH. Consequently, the thresholds for discriminating between different severity grades have to be adjusted in MSCT.

Precision of forty slice spiral computed tomography for quantifying aortic valve stenosis: comparison with echocardiography and validation against cardiac catheterization.

OBJECTIVES: We evaluated the precision of multislice spiral computed tomography (MSCT) for the quantification of aortic valve stenosis in comparison with echocardiography and cardiac catheterization. MATERIALS AND METHODS: An electrocardiogram-gated MSCT scan (detector collimation 40 x 6.25 mm, gantry rotation time 420 milliseconds, pitch 0.2, tube voltage 120 KV, tube current 333 mA) was performed in 32 patients with known aortic valve stenosis. In each patient the aortic valve orifice area (AVA) was determined by planimetry on MSCT and compared with the results obtained from transthoracic Doppler echocardiography (using the continuity equation) and cardiac catheterization (using the Gorlin formula). RESULTS: Planimetry of the AVA on MSCT was feasible in all cases. The AVA on MSCT (1.11 +/- 0.49 cm2) was significantly larger compared with echocardiography (0.81 +/- 0.37 cm2, P < 0.001) and cardiac catheterization (0.87 +/- 0.45 cm2, P < 0.001). The correlations between MSCT and echocardiography (r = 0.86, limits of agreement +/-0.52 cm2) and also between MSCT and cardiac catheterization (r = 0.90, limits of agreement +/-0.44 cm2) were good, but inferior to the correlation between echocardiography and cardiac catheterization (r = 0.94, limits of agreement +/-0.32 cm2). Using an AVA of 1.0 cm at cardiac catheterization as reference standard, the best cut-off level for detecting severe-to-critical stenosis at MSCT was an AVA of 1.20 cm, resulting in a sensitivity, specificity, and accuracy of 91%, 100%, and 94%, respectively. CONCLUSIONS: AVA determined by MSCT correlates well with echocardiography and cardiac catheterization. However, AVA derived from MSCT is consistently larger, requiring an adjustment of cut-off values for the classification of stenosis severity and therapeutic decision making.