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Interventional imaging is a fast growing field based on the constant improvement of real time image acquisition and analysis in various imaging modalities. Interventional imaging brings new clinical applications where various imaging modalities are used intra-operatively to assist medical or surgical procedures. Modern medical imaging modalities (ultrasound, fluoroscopy, CT, MRI, video, etc.) produce high resolution images of the human body that can be used to precisely guide surgical instruments or to monitor treatment in real time. Current challenges in interventional imaging are, for example, the compensation for physiological motions during image-guided interventional procedures, image-registration of moving and deformable organs, and the development of intra-operative devices.

Coordinator: M. de Mathelin
Project Manager: J-F. Kong

1. Navigation and augmented reality

Navigation of surgical instruments consists of real time registration of the instruments with respect to anatomical landmarks or fiducials and pre-operative images (CT-scan, MRI, etc.) in order to provide the doctor an accurate positioning of the instruments during the procedure according to a pre-operative planning. The registration is often made using infrared cameras and fiducials, but can also be performed with video cameras, stereotactic markers and scanned images, or magnetic tracking devices, to cite a few techniques. Augmented reality provides pre-operative data on intra-operative images and requires a real-time registration between the intra-operative view and the pre-operative images. An important challenge is in applications to moving and deformable organs. Algorithms that can register pre-operative data on intra-operative data in a moving and deformable environment are required. Examples of applications are: compensation for brain shift during neurosurgery, or that for breathing motion in laparoscopic surgery or heart-beat tracking during cardiac surgery. Another challenge is to provide non-rigid fusion algorithms between intra-patient images from different modalities. A research issue is also the development of robust registration algorithms without the use of fiducials or markers on the patient, based only on the intra-operative images and regions of interest defined by the doctor.

Node partners: Grenoble, IAM (Strasbourg, Brest)
Others: Strasbourg, Rennes

2. Robotized imaging systems

Imaging devices need to be fixed or moved precisely in space in order to acquire the images and data. Indeed, by moving endoscopes in a controlled manner, depth reconstruction and mosaics can be performed. By robotizing flexible endoscopes, it becomes possible to perform complex surgery through natural orifices (NOTES) or by single port access. Having flat panel sensors on robot arms moving in space allows for 3D reconstruction of volumes of interest. Robotizing imaging instruments can transform them into moving “eyes” that follow the instructions of the doctor in order to optimize the acquired data at any instant with respect to the medical task to perform.

Node partners: Grenoble, IAM (Strasbourg, Brest)
Others: Strasbourg, Rennes, Paris

3. MR guided interventions

Real time MRI guidance
Recent developments in MRI technology have brought wide bore MRI machines where the tunnel is sufficiently large so that it is possible to perform interventions on the patient inside the machine. For example, Strasbourg (LSIIT-ICube) has a dedicated machine to interventional radiology for more than two years where percutaneous procedures are performed on patients inside the tunnel. Beside simple operations like biopsies and infiltrations, cryo-ablation of tumors is also performed with the advantage of an excellent contrast provided by the ice ball compared with RF ablation, without disturbing the image acquisition. The planning of the intervention is a research issue and requires the modeling of the procedure based on thermodynamics, taking into account the fact that several needles will be needed simultaneously. The accurate positioning of the needles and instruments will require a modeling of the artifacts and their correction, as well as an aid to the positioning and guidance of the needle. Optimization of real-time MRI sequences and workflows are needed in other to provide procedures with reduced machine time. Motion compensation algorithms need to be developed for applications to target moving organs.

MR compatible instruments
The development of interventional MRI requires new MR compatible instruments and devices. It will be interesting to combine optical views with real-time MRI. Surgical instruments and needles need to be optimized with respect to their artifacts. Coils can be optimized for the surgical procedures. The electronics needs to be compatible with the MRI acquisition.

Node partners: IAM (Strasbourg, Nancy)
Others: Strasbourg
Industrial partners: Siemens, GE

4. Ultrasound based therapies

Based on US equipments described in WP2, therapeutic use of US technology can be developed.

High Intensity Focused Ultrasound (HIFU)
New devices and software need to be designed to go further than the current approved clinical applications, namely, uterine fibroids and transrectal prostate resection. Thus, application to brain therapies would require the development of HIFU systems that take into account the patient skull in order to avoid bone reflexion-induced injuries. In order to target organs inside the chest or the abdomen, the HIFU systems will have to take into account the presence of bones in the path, the heterogeneity of the different tissues, and the physiological motions due to breathing and heart beating. Real-time temperature monitoring or elastography will have to be developed for the monitoring of HIFU therapy. MRI can be used for this monitoring if proper gradient sequences are developed.

Targeted vectorization
Localized delivery of active ingredients is possible via the release of specific therapeutic agents induced by ultrasound. HIFU are either use to heat a specific target or to destruct microbubbles by cavitation (ultrasound-targeted microbubble-destruction - UTMD).

Node partners: Paris Centre, Lyon, Bordeaux, IAM (Strasbourg)
Others: Strasbourg

5. Intra-operative imaging with dedicated small devices

Dedicated small devices must be developed for use inside the operating theatre (OT) for intra-operatively monitoring of the surgery. Indeed, during surgery for cancer treatment, it is crucial to verify in real time if all the cancerous tissue has been removed with a proper safety margin; often the sentinel lymph nodes draining the lesion must also be checked. If this information can be gathered intra-operatively, then the surgery can be completed successfully. Different modalities are interesting for this purpose: fluorescence imaging, ionizing radiation imaging (single photon, TEP/CT), and MRI. The challenges are to make these imaging modalities compatible with the constraints of use in the OT and to develop adequate surgical workflows for useful clinical indications.

Node partners: Paris-Sud, Grenoble, IAM (Strasbourg)
Others: Strasbourg, Lille