Active motion compensation for cardiac surgery

Transcription

1 Active motion compensation for cardiac surgery Prof. Dr. Ing. Philippe POIGNET LIRMM UMR 5506 CNRS - University of Montpellier RoboDcs Department, France poignet@lirmm.fr BioDev 14

2 LIRMM / Robo)cs Dpt / DEXTER Team / Med. Rob. Group Med. Rob. Team: 4 permanents, 1 Emeritus, 3 research engineers, 6 PhDs, few residents, International collaborations: - WASEDA University, - University of Washington - Université Catholique de Louvain (UCL) - Scuela Superiore Santa Anna (SSSA) - Politecnico di Milano - 2

3 Evolution of surgery n How to improve the surgical techniques? the quality and the safety of gesture? the patient and surgeon benefit? ENDOLUMINAL or INTRAVASCULAR SURGERY MINIMALLY INVASIVE SURGERY (MIS) ASSISTED MIS da Vinci system Endoscopic and intra vascular micro-devices

4 Minimally Invasive Surgery Limita)ons: Monocular vision Decreased mobility (source : Hand- eye coordinadon Three hands required No tacdle feedback Surgeon posidon 4

5 Robo)zed MIS RoboDc assistance can overcome most of the difficuldes of MIS: Increased dexterity Improved ergonomics Enhanced visualizadon Tremor filtering 5

6 Ac)ve vision- based mo)on compensa)on R. Richa, P. Poignet, C. Liu, 2010, 3D modon tracking for beadng heart surgery,interna)onal Journal of Robo)cs Research 29(2), pp R. Richa, A. Bo, P. Poignet, 2011, Towards Robust 3D Visual Tracking for MoDon CompensaDon in BeaDng Heart Surgery, Medical Image Analysis 15(3), pp

7 The Coronary Artery Bypass GraLing (CABG) Approximately CABGs per year in France and in USA [MSS09] The reference procedure ü Median sternotomy ü Cardiopulmonary bypass ( ) Although high success rates are observed, the downsides for padents are not negligible ü Risks of microemboly ü Neurological complicadons ü ü Trauma 7

8 The Off- pump minimally invasive CABG Avoids the trauma caused by the median sternotomy ü Less risks, costs and trauma ü Shorter convalescence Dme Mechanical stabilizers for operadng on the beadng heart Octopus, Medtronic 8

9 Specifica)ons for CABG Suturing (sdtching + knot tying) Ø 2 mm, 10 to 20 penetradons Ø of the thread: few tens of mm PenetraDon force: up to 1N ResoluDon: beger than 0.1 mm graft Suturing of the graft to the aorta and the coronary artery CABG requires micro- manipuladon RoboDc assistance for circumvendng MIS limitadons Need of automadc compensadon of physiological modons 9

10 Mechanical stabilizer Passive stabilizer AcDve stabilizer Compliant joints Visual Markers High speed camera Octopus, Medtronic Piezo-motor Cardiolock, ICube, Strasbourg 10

11 Mobile robot instrument an inchworm- like mobile robot for minimally- invasive beadng- heart cardiac surgery HeartLander (The Robotics Institute, CMU, Pittsburgh) 11

12 Vision- based stabilizer Vision- based modon compensadon ü ObjecDve: accurate esdmadon of the heart surface modon without ardficial markings ü It is pracdcal but is it feasible? DifficulDes ü High acceleradons ü Complex dynamics ü IlluminaDon changes and specular reflecdons ü Occlusions due to surgical instruments, blood, smoke, etc. Endoscopic CABG using the DaVinci 12

13 Related works In the literature, visual tracking methods for esdmadng the heart modon can be coarsely divided into two classes Feature- based tracking [Ortmaier02, Stoyanov05a, Noce06, Mountney08] ü Tracking a set of natural structures on the heart surface (e.g. blood vessels, salient Dssue) Region- based tracking [Lau 04, Stoyanov05b, Lo08b, Richa08c] ü EsDmaDon of the deformadon of a whole region of interest based on a parametric model (e.g. B- spline, Radial Basis FuncDons) è Problem: finding a suitable deformadon model 13

14 Tracking using a Thin- Plate Spline deformable model The TPS is a radial basis funcdon used to specify an approximadon funcdon f which minimizes the bending energy [Bookstein89] where U(s) = s²log(s) is the TPS basis funcdon 2D warping parameterizadon [Lim 05] Tracking M i and K * can be pre- computed h x and h y are the stacked x and y coordinates of the control points correspondances c 14

15 3D Tracking in stereo images A mapping from R 2 R 3 can be wrigen by stacking 3 TPS equadons [Malis06] The control points on each stereo image as projecdons of 3D points onto the image plane fz EsDmaDon of 3D points X that minimize the alignment error between the reference image T and both stereo images I l and I r simultaneously 15

16 Model assessment The 3D shape of an ex vivo pig s heart is scanned by a laser profilometer (0.2 mm depth precision) The error between the ground truth and the TPS approximadon is measured Detail TPS approximadon 4cm x 4cm region - 25 control points Average error: 0.24 mm Standard DeviaDon: 0.29 mm Maximum Error: 1.1 mm 16

17 Experimental results Robust to changes in illuminadon and specular reflecdon Occlusion is not yet considered here. 17

18 Predic)ng the bea)ng heart mo)on Proposed model: a non- stadonary dual Fourier series ü f contains the series parameters ü ω r respiratory frequency ü ω c cardiac frequency ü H r N o respiradon harmonics ü H c N o cardiac harmonics The parameters are esdmated with EKF [Richa et al., 10] 18

19 Predic)ng the bea)ng heart mo)on RMS / peak prediction errors: 0.2s : 0.73mm / 1mm 1s : 0.86mm / 1.55mm 3s : 1.00mm / 2.03mm 19

20 Summary Efficient hybrid tracking approach for 3D esdmadon of the heart surface Robust w.r.t.: ü IlluminaDon changes ü Specular reflecdons ü Large deformadon PredicDve model based on dual Fourier series for tackling tracking failures and occlusions Experiments on in vivo images Parallel computadons are possible allowing the future implementadon in a control scheme 20

21 Thank you for your a_en)on R. Richa, P. Poignet, C. Liu, 2010, 3D modon tracking for beadng heart surgery,interna)onal Journal of Robo)cs Research 29(2), pp R. Richa, A. Bo, P. Poignet, 2011, Towards Robust 3D Visual Tracking for MoDon CompensaDon in BeaDng Heart Surgery, Medical Image Analysis 15(3), pp