Biomedical subjects

Redha Boubertakh

Publications and source records attributed to Redha Boubertakh.

3 recordsLinked to original sources

PubMed2006

Interactive MR imaging and tracking of catheters with multiple tuned fiducial markers.

PURPOSE: The lack of magnetic resonance (MR) safe catheters and guide wires remains an important obstacle to widespread clinical use of MR-guided endovascular procedures. The authors looked at the feasibility of using multiple tuned fiducial markers (TFM) and novel imaging sequences to track catheters reliably under MR and to evaluate the safety of such markers in terms of heating. MATERIALS AND METHODS: The visualization and tracking of a catheter with six quadrature tuned fiducial coils was carried out in a special designed in-vitro setup within a 1.5-T MR imager simulating an MR-guided endovascular intervention. The fiducial markers were also tested for heating. RESULTS: The excellent signal contrast between the fiducial and the background when using novel interleaved real time and interactive sequences allowed for rapid and reliable identification of the fiducial markers and therefore the catheter. No significant heating of the marker was noted. CONCLUSIONS: The authors have shown that catheters with multiple tuned fiducial markers are superior to passive catheter designs in terms of visualization and do not carry the risk of heating that is commonly associated with active catheters.

Cardiac Catheterization↗

PubMed2005

Dynamic three-dimensional undersampled data reconstruction employing temporal registration.

Dynamic 3D imaging is needed for many applications such as imaging of the heart, joints, and abdomen. For these, the contrast and resolution that magnetic resonance imaging (MRI) offers are desirable. Unfortunately, the long acquisition time of MRI limits its application. Several techniques have been proposed to shorten the scan time by undersampling the k-space. To recover the missing data they make assumptions about the object's motion, restricting it in space, spatial frequency, temporal frequency, or a combination of space and temporal frequency. These assumptions limit the applicability of each technique. In this work we propose a reconstruction technique based on a weaker complementary assumption that restricts the motion in time. The technique exploits the redundancy of information in the object domain by predicting time frames from frames where there is little motion. The proposed method is well suited for several applications, in particular for cardiac imaging, considering that the heart remains relatively still during an important fraction of the cardiac cycle, or joint imaging where the motion can easily be controlled. This paper presents the new technique and the results of applying it to knee and cardiac imaging. The results show that the new technique can effectively reconstruct dynamic images acquired with an undersampling factor of 5. The resulting images suffer from little temporal and spatial blurring, significantly better than a sliding window reconstruction. An important attraction of the technique is that it combines reconstruction and registration, thus providing not only the 3D images but also its motion quantification. The method can be adapted to non-Cartesian k-space trajectories and nonuniform undersampling patterns.

Algorithms↗

PubMed2005

Inter-breath-hold registration for the production of high resolution cardiac MR volumes.

High resolution MRI images of the beating heart permit observation of detailed anatomical features and enable quantification of small changes in metrics of cardiac function. To obtain approximately isotropic sampling with an adequate spatial and temporal resolution, these images need to be acquired in multiple breath-holds. They are, therefore, often affected by through-plane discontinuities due to inconsistent breath-hold positions. This paper presents a method to correct for these discontinuities by performing breath-hold-by-breath-hold registration of high resolution 3D data to radial long axis images. The corrected images appear free of discontinuities, and it was found that they could be delineated more reproducibly than uncorrected images. This reduces the sample size required to detect systematic changes in blood pool volume by 57% at end systole and 78% at end diastole.

Algorithms↗