Thorac Cardiovasc Surg 2013; 61 - SC17
DOI: 10.1055/s-0032-1332515

Manual versus automatic detection of aortic annulus plane in CT scan for T-AVI screening

A Van Linden 1, J Kempfert 1, J Blumenstein 1, H Möllmann 2, WK Kim 1, 2, S Alkaya 1, T Ziegelhöffer 1, C Hamm 2, T Walther 1
  • 1Kerckhoff-Klinik, Herzchirurgie, Bad Nauheim, Germany
  • 2Kerckhoff-Klinik, Kardiologie, Bad Nauheim, Germany

Objectives: Precise measurements of aortic annulus dimensions are crucial for prosthesis size selection in patients undergoing transcatheter aortic valve implantation (T-AVI). So called effective diameter (derived from area) measured in multislice computed tomography (MSCT) images has evolved to be the most precise measurement tool. Usually the operator must manually adjust the aortic annulus plane. Aortic ValveGuide (Siemens Healthcare) is a new software tool that allows for automatic aortic root reconstruction and annulus plane detection. Aim of this study was to compare the effective diameter measured in automatically detected and manually adjusted annulus plane.

Methods: 73 raw image datasets of preoperative T-AVI MSCT scans were analyzed using our institutional golden standard (3 Mensio) with manual annulus plane adjustment and using Aortic ValveGuide with automatic annulus plane detection (Figure 1). The aortic annulus circumference was manually marked for both software tools and the effective diameter was calculated using the formula: effective diameter = 2* ((sqrt))(circumferential area/π). All measurements were performed in diastole.

Results: Automatic annulus plane detection worked well in all MSCT scans. Minor manual adjustment of the plane was necessary in only 3 patients. Mean effective aortic annulus diameter was 22.9 ± 2.4 mm for 3 Mensio and 23.3 ± 2.5 mm for Aortic ValveGuide. Bland-Altman analysis of both imaging software tools showed good agreement (mean difference 0.32 mm, limits of agreement -0.91 – 1.56 mm).

Conclusion: Effective aortic annulus diameter measured with Aortic ValveGuide shows good agreement to golden-standard measurements. Automatic annulus plane detection reduces the effort for MSCT analysis and may lead to more reproducible aortic annulus measurements. Aortic ValveGuide is part of the DynaCT and in future aortic annulus dimension measurements may be feasible during intraoperative acquired DynaCT.

Fig. 1: DynaCT left and 3 Mensio right