Biomechanical modelling of the lung deflation
for image guided thoracic surgery
MSc internship proposal supported by the LABEX CAMI, http://www.cami-labex.fr
Internship location:
TIMC-IMAG lab, University of Grenoble, CNRS, France
In collaboration with LTSI lab, University of Rennes, INSERM, France
Collaborators:
Contact:
Matthieu Chabanas (Associate Professor), Yohan Payan (Senior Researcher), TIMC-IMAG
Simon Rouze (Medical resident), Miguel Castro (Research Engineer), LTSI
[email protected]
Duration:
6 month, starting in spring 2016.
1. Background
Recent studies established the interest screening programs and low-dose CT to detect early stage of lung cancer.
Therefore, diagnosis of nodules with unknown histology is increasing dramatically. Lung biopsies performed through
video assisted thoracic surgery (VATS) usually provide sufficient material for histological diagnosis. However
localization of these lesions may represent a real surgical challenge. Several guidance systems have been developed.
The more accurate ones are invasive and require a preoperative procedure under CT-fluoroscopic guidance (i.e.
hooks, coils). Moreover, these techniques may be associated with pleural effusion and targeting errors. On the other
hand, Cone Beam Computed Tomography (CBCT) is an increasingly used guidance modality. CBCT has previously
shown interesting results in the thoracic field like interventional pneumology during a bronchoscopy, biopsy
guidance in radiology or during radiotherapy.
However, in thoracic surgery, CBCT guidance during the surgical procedure has not yet been investigated in clinical
practice. The main obstacle of this guidance procedure is the creation of a pneumothorax at the beginning of the
surgery, and consequently a collapse of the lung. This deflation of the lung is not homogenous: it is more important
on the outskirts of the lung, in opposition to the hilum region, which is more rigid, immobile and undeformable
(mainly because of the bronchus and vascular structures). Because of the collapse of the lung, its density is changing
as well, becoming more important.
The increasing of the density and the deformations of the lung related to the pneumothorax can make the
localization of the lesions really challenging, especially for small ones.
2. Objectives of the Master’s internship
Every patient benefit from a pre-operative CT, which can be segmented to identify target lesions. The aim of this
work is thus to propose a model of the lung to infer the location of these lesions in the new conformation of the
deflated lung. A first solution could then be proposed for the interactive 3D localization of lesions in per-operative
CBCT images.
This work should include:


Studying the biomechanical specificities of the lung ;
Creating a biomechanical model of the lung, including inner structures like the bronchial tree, to predict its
behaviour when deflated.
The CAMI LABEX is co-funded by the ANR within the Investissements d'Avenir programme
under reference ANR-11-LABX-0004


Using this biomechanical model to perform the patient specific registration between pre-operative CT of the
inflated lung and intra-operative CBCT of the deflated lung. A first step will be to match the two
conformations of the bronchial tree, then use the biomechanical model as a non-linear interpolator of the
deformations all over the lung. Therefore, the lesions locations could be estimated in the CBCT images to
guide the clinician during his procedure.
This process a shown promising results in other context, especially in Neurosurgery with a brain
biomechanical model guided by the tracked deformations of the vascular tree [4].
Evaluating of the proposed solution.
Given the potential of this application and the large amount of requirements, there is a strong possibility of a
continuation of this work during a PhD.
3. Requirements for the candidate



Background in Computer Science and/or (Bio)mechanical Engineering
Experiences in Modelling and Simulation, Medical Image Processing, C++ programming
Strong interest for Medical Applications
Left: images of the inflated and deflated lung, with creation of a pneumothorax (images from [1])
Right: VATS procedure of the lung (images from [3])
4. References
[1] Uneri A, Nithiananthan S, Schafer S, Otake Y, Stayman JW, Kleinszig G, Sussman MS, Prince JL, Siewerdsen JH. Deformable registration of
the inflated and deflated lung in cone-beam CT-guided thoracic surgery: initial investigation of a combined model- and image-driven approach.
Med Phys. 2013 Jan;40(1):017501
[2] Naini AS, Pierce G, Lee TY, Patel RV, Samani A. CT image construction of a totally deflated lung using deformable model extrapolation. Med
Phys. 2011 Feb; 38(2):872-83.
[3] S.Rouzé, M. Castro, P. Haigron, J.P. Verhoye, B. de Latour. Small pulmonary nodule localization with intraoperative CBCT during videoassisted thoracic surgery. SURGETICA proceedings, Chambéry, France, Dec. 2014.
[4] M. Bucki, O. Palombi, M. Bailet, Y. Payan. Doppler Ultrasound Driven Biomechanical Model of the Brain for Intraoperative Brain-Shift
Compensation: A Proof of Concept in Clinical Conditions. Y. Payan. Soft Tissue Biomechanical Modeling for Computer Assisted Surgery,
Springer-Verlag, pp.135-165, 2012, Studies in Mechanobiology, Tissue Engineering and Biomaterials, 978-3-642-29013-8.
The CAMI LABEX is co-funded by the ANR within the Investissements d'Avenir programme
under reference ANR-11-LABX-0004