Korean J Radiol.  2010 Apr;11(2):169-177. 10.3348/kjr.2010.11.2.169.

Planimetric Measurement of the Regurgitant Orifice Area Using Multidetector CT for Aortic Regurgitation: a Comparison with the Use of Echocardiography

• Jeon MH
• Choe YH
• Cho SJ
• Park SW
• Park PW
• Oh JK

• KMID: 1783193
• DOI: http://doi.org/10.3348/kjr.2010.11.2.169

Abstract

OBJECTIVE
This study compared the area of the regurgitant orifice, as measured by the use of multidetector-row CT (MDCT), with the severity of aortic regurgitation (AR) as determined by the use of echocardiography for AR.
MATERIALS AND METHODS
In this study, 45 AR patients underwent electrocardiography-gated 40-slice or 64-slice MDCT and transthoracic or transesophageal echocardiography. We reconstructed CT data sets during mid-systolic to enddiastolic phases in 10% steps (20% and 35-95% of the R-R interval), planimetrically measuring the abnormally opened aortic valve area during diastole on CT reformatted images and comparing the area of the aortic regurgitant orifice (ARO) so measured with the severity of AR, as determined by echocardiography.
RESULTS
In the 14 patients found to have mild AR, the ARO area was 0.18+/-0.13 cm2 (range, 0.04-0.54 cm2). In the 15 moderate AR patients, the ARO area was 0.36 +/- 0.23 cm2 (range, 0.09-0.81 cm2). In the 16 severe AR patients, the ARO area was 1.00 +/- 0.51 cm2 (range, 0.23-1.84 cm2). Receiver-operator characteristic curve analysis determined a sensitivity of 85% and a specificity of 82%, for a cutoff of 0.47 cm2, to distinguish severe AR from less than severe AR with the use of CT (area under the curve = 0.91; 95% confidence interval, 0.84-1.00; p < 0.001).
CONCLUSION
Planimetric measurement of the ARO area using MDCT is useful for the quantitative evaluation of the severity of aortic regurgitation.

Keyword

Computed tomography (CT); Echocardiography; Aortic regurgitation; Planimetry

MeSH Terms

Adolescent
Adult
Aged
Aged, 80 and over
Aortic Valve/physiopathology/radiography/ultrasonography
Aortic Valve Insufficiency/*radiography/*ultrasonography
Area Under Curve
Body Weights and Measures/methods
Echocardiography/methods
Echocardiography, Doppler, Color/methods
Echocardiography, Transesophageal/methods
Electrocardiography
Female
Humans
Male
Middle Aged
ROC Curve
Retrospective Studies
Sensitivity and Specificity
Severity of Illness Index
Tomography, X-Ray Computed/*methods
Young Adult

Figure

• 

  Fig. 1 Demonstration of CT raw data reconstruction and aortic regurgitant orifice measurement at workstation, in 71-year-old male patient with moderate aortic regurgitation shown by transthoracic echocardiography. In this particular patient, image reconstruction was performed in 5% steps instead of 10% steps of our CT protocol. A. Aortic valve area was chosen from CT scout image to reconstruct images of multiple cardiac phases. B. Short-axial images of aortic valve, showing exact regurgitant orifice area produced from two orthogonal aortic longitudinal planes. C. Resultant aortic valve short-axial images in multiple planes (5-95% in 5% steps) show almost same regurgitant areas of aortic valve during diastolic phases. Image quality is excellent during mid-diastole (65-85%). D, E. In this case, aortic regurgitant orifice area via CT measured 0.31 cm2. Vena contracta, effective regurgitant orifice, and pressure half-time at echocardiography were 0.44 cm, 0.30 cm2, and 272 ms, respectively.

• 

  Fig. 2 60-year-old male with mild central aortic regurgitation shown by transthoracic echocardiography. A. Image shows batch reconstruction of aortic valve short-axial images in 1 mm thicknesses and 1 mm intervals. B. Resultant image visualizes central coaptation failure zone of 0.17 cm2 (arrow) and fusion of left and noncoronary cusps. Small areas of coaptation failure in peripheral commissure of aortic valve were suspected (arrowheads). C. Virtual angioscopic image confirms central regurgitation area (arrow). However, there was no evidence of commissural incompetency in periphery.

• 

  Fig. 3 76-year-old male with infective endocarditis and moderate eccentric aortic regurgitation and stenosis shown by transthoracic echocardiography. A. Reformatted image shows diastolic coaptation failure with valvular thickening and calcifications. Aortic regurgitant orifice at CT was 0.64 cm2. B. Long-axial image of aortic valve demonstrates 0.5 cm-vegetation (arrow) attached to valve leaflet. Vena contracta was 0.43 cm, and pressure half-time measured 183 ms at echocardiography.

• 

  Fig. 4 37-year-old male with severe aortic regurgitation shown by transthoracic echocardiography. Reformatted CT image shows large area (asterisk) of commissural incompetency between right and left coronary cusps. Aortic regurgitant orifice area via CT measured 1.49 cm2. Effective regurgitant orifice area was 0.82 cm2 and pressure half-time, 259 ms at echocardiography.

• 

  Fig. 5 38-year-old male with right coronary cusp prolapse and eccentric aortic regurgitation. A. Reformatted image shows prolapsed right coronary cusp (arrowhead) and coaptation failure of aortic valve (arrow). B. Dotted lines A and B indicate image reconstruction planes for central aortic regurgitation and eccentric aortic regurgitation with prolapsed cusp, respectively. C. Image reconstructed along plane A shows ovoid area (between arrows), indicating prolapsed part of right coronary cusp, not aortic regurgitant orifice. D. Image reconstructed along plane B shows aortic regurgitant orifice (between arrows). E. Virtual angioscopic image shows eccentric aortic regurgitant orifice (arrow).

• 

  Fig. 6 Scatter plot of data shows significant difference in aortic regurgitant orifice area via CT between patients with severe AR and those with mild to moderate AR, determined with use of transthoracic echocardiography. AR = aortic regurgitation, ARO = aortic regurgitant orifice

• 

  Fig. 7 Receiver operation characteristic curve analysis shows accuracy of aortic regurgitant orifice area via CT in discriminating mild aortic regurgitation from moderate to severe aortic regurgitation (A) and mild to moderate aortic regurgitation from severe aortic regurgitation (B). Optimal cutoff values for mid aortic regurgitation and severe aortic regurgitation were 0.27 cm2 and 0.47 cm2, respectively. ARO = aortic regurgitant orifice

• 

  Fig. 8 Correlation between aortic regurgitant orifice area via CT and vena contracta width shown by transthoracic echocardiography (r = 0.68, p < 0.001). ARO = aortic regurgitant orifice

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