TY  - JOUR
A1  - Karar, Mohamed Esmail
A1  - Falk, Volkmar
A1  - Burgert, Oliver
T1  - Intra-operative fluoroscopy-guided assistance system for transcatheter aortic valve implantation
JF  - International journal of computer assisted radiology and surgery
N2  - A new surgical assistance system has been developed to assist the correct positioning of the AVP during transapical TAVI. The developed assistance system automatically defines the target area for implanting the AVP under live 2-D fluoroscopy guidance. Moreover, this surgical assistance system works with low levels of contrast agent for the final deployment of AVP, reducing therefore long-term negative effects, such as renal failure in the elderly and high-risk patients.
KW  - aortic valve replacement
KW  - image-guided intervention
KW  - minimally invasive surgery
KW  - x-ray fluoroscopy
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bsz:rt2-opus4-460
SN  - 1861-6410
VL  - 9
IS  - Supplement 1
SP  - 109
EP  - 110
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Karar, Mohamed Esmail
A1  - Merk, Denis
A1  - Falk, Volkmar
A1  - Burgert, Oliver
T1  - A simple and accurate method for computer-aided transapical aortic valve replacement
JF  - Computerized medical imaging and graphics
N2  - Background and purpose: Transapical aortic valve replacement (TAVR) is a recent minimally invasive surgical treatment technique for elderly and high-risk patients with severe aortic stenosis. In this paper,a simple and accurate image-based method is introduced to aid the intra-operative guidance of TAVR procedure under 2-D X-ray fluoroscopy.
Methods: The proposed method fuses a 3-D aortic mesh model and anatomical valve landmarks with live 2-D fluoroscopic images. The 3-D aortic mesh model and landmarks are reconstructed from interventional X-ray C-arm CT system, and a target area for valve implantation is automatically estimated using these aortic mesh models.Based on template-based tracking approach, the overlay of visualized 3-D aortic mesh model, land-marks and target area of implantation is updated onto fluoroscopic images by approximating the aortic root motion from a pigtail catheter motion without contrast agent. Also, a rigid intensity-based registration algorithm is used to track continuously the aortic root motion in the presence of contrast agent.Furthermore, a sensorless tracking of the aortic valve prosthesis is provided to guide the physician to perform the appropriate placement of prosthesis into the estimated target area of implantation. 
Results: Retrospective experiments were carried out on fifteen patient datasets from the clinical routine of the TAVR. The maximum displacement errors were less than 2.0 mm for both the dynamic overlay of aortic mesh models and image-based tracking of the prosthesis, and within the clinically accepted ranges. Moreover, high success rates of the proposed method were obtained above 91.0% for all tested patient datasets.
Conclusion: The results showed that the proposed method for computer-aided TAVR is potentially a helpful tool for physicians by automatically defining the accurate placement position of the prosthesis during the surgical procedure.
KW  - aortic valve
KW  - biomedical image processing
KW  - computer-aided surgery
KW  - image-guided intervention
KW  - minimally invasive cardiac surgery
KW  - X-ray fluoroscopy
Y1  - 2016
U6  - http://dx.doi.org/10.1016/j.compmedimag.2014.09.005
SN  - 0895-6111
VL  - 50
IS  - Special Issue on Computer Assisted Stenting
SP  - 31
EP  - 41
PB  - Elsevier
CY  - Amsterdam
ER  -