Standardized 2D ultrasound versus 3D/4D ultrasound and image fusion for measurement of aortic aneurysm diameter in follow-up after EVAR.
OBJECTIVE
To compare standardised 2D ultrasound (US) to the novel ultrasonographic imaging techniques 3D/4D US and image fusion (combined real-time display of B mode and CT scan) for routine measurement of aortic diameter in follow-up after endovascular aortic aneurysm repair (EVAR).


METHODS
300 measurements were performed on 20 patients after EVAR by one experienced sonographer (3rd degree of the German society of ultrasound (DEGUM)) with a high-end ultrasound machine and a convex probe (1-5 MHz). An internally standardized scanning protocol of the aortic aneurysm diameter in B mode used a so called leading-edge method. In summary, five different US methods (2D, 3D free-hand, magnetic field tracked 3D - Curefab™, 4D volume sweep, image fusion), each including contrast-enhanced ultrasound (CEUS), were used for measurement of the maximum aortic aneurysm diameter. Standardized 2D sonography was the defined reference standard for statistical analysis. CEUS was used for endoleak detection.


RESULTS
Technical success was 100%. In augmented transverse imaging the mean aortic anteroposterior (AP) diameter was 4.0±1.3 cm for 2D US, 4.0±1.2 cm for 3D Curefab™, and 3.9±1.3 cm for 4D US and 4.0±1.2 for image fusion. The mean differences were below 1 mm (0.2-0.9 mm). Concerning estimation of aneurysm growth, agreement was found between 2D, 3D and 4D US in 19 of the 20 patients (95%). Definitive decision could always be made by image fusion. CEUS was combined with all methods and detected two out of the 20 patients (10%) with an endoleak type II. In one case, endoleak feeding arteries remained unclear with 2D CEUS but could be clearly localized by 3D CEUS and image fusion.


CONCLUSIONS
Standardized 2D US allows adequate routine follow-up of maximum aortic aneurysm diameter after EVAR. Image Fusion enables a definitive statement about aneurysm growth without the need for new CT imaging by combining the postoperative CT scan with real-time B mode in a dual image display. 3D/4D CEUS and image fusion can improve endoleak characterization in selected cases but are not mandatory for routine practice.
Division of Vascular and Endovascular Surgery, University Medical Center Regensburg, Regensburg, Germany.
Karin
K
Pfister
Division of Vascular and Endovascular Surgery, University Medical Center Regensburg, Regensburg, Germany.
Wilma
W
Schierling
Institute of Diagnostic Radiology, University Medical Center Regensburg, Regensburg, Germany.
Ernst Michael
EM
Jung
Division of Vascular and Endovascular Surgery, University Medical Center Regensburg, Regensburg, Germany.
Hanna
H
Apfelbeck
Computer Aided Medical Procedures (CAMP), Technische Universitaet Munchen, Garching, Germany.
Christoph
C
Hennersperger
Division of Vascular and Endovascular Surgery, University Medical Center Regensburg, Regensburg, Germany.
Piotr M
PM
Kasprzak
D000368:Aged; D000369:Aged, 80 and over; D001014:Aortic Aneurysm / Q000000981:diagnostic imaging* / Q000601:surgery; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000601:surgery; D003287:Contrast Media; D057867:Endoleak; D005260:Female; D005500:Follow-Up Studies; D056973:Four-Dimensional Computed Tomography / Q000379:methods; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed / Q000379:methods; D014463:Ultrasonography / Q000379:methods*; D018615:Ultrasonography, Doppler, Color / Q000379:methods*; D014656:Vascular Surgical Procedures
D003287:Contrast Media
3D ultrasound; 4Dultrasound; Aortic aneurysm diameter; EVAR surveillance; image fusion; ultrasonographic imaging techniques