A pilot study to quantify hepatic perfusion using pseudo-continuous arterial spin labeling in MRI

Congrès sous l’égide de la Société Française de Génie Biologique et Médical (SFGBM)National audienceThis study aimed at optimizing a pseudo-Continuous Arterial Spin Labeling (pCASL) approach to quantify hepatic perfusion in MRI. Six volunteers were examined using a 3T Siemens scanner, pCASL sequences with 4 and 20 repetitions were acquired in a plane orthogonal to portal vein with a post label delay (PLD) of 600 ms. For two subjects, four additional PLD (varying from 1000 to 1600 ms) were tested. Data were processed using specific software, which computes parametric maps of hepatic perfusion (HP). Global results show a more robust HP estimation when using 20 repetitions. The five PLD values provided hepatic perfusion weighted differently by the hepatic artery and the portal vein blood flows. This strategy could be used to estimate separately these two components

Usefulness of Tc-99m Sestamibi studies for monitoring response to therapy in patients with high grade gliomas: a preliminary study

Congrès sous l’égide de la Société Française de Génie Biologique et Médical (SFGBM).National audienceEarly and late Sestamibi studies were acquired in addition to conventional MRI protocol in 14 patients with high-grade gliomas to monitor an antiangiogenic treatment. Global and local indices were deduced from these SPECT studies and were compared with progression free survival (PFS) and overall survival (OS). Variations of intensity in late studies were not correlated with PFS, but were related to OS. This suggests the possible role of Sestamibi for monitoring response to treatment

Detection of recurrent nerve paralysis: Development of a Computer Aided Diagnosis system

International audienceRecurrent nerve paralysis (RP) is one of the most frequent complications of thyroid surgery. It reduces vocal fold mobility. Nasal endoscopy, a mini-invasive procedure, is the reference procedure to detect RP, and is based on the examination of vocal fold mobility. A new approach based on laryngeal ultrasound acquisition and using a dedicated data analysis was designed to help with the automated detection of RP. One hundred and fifty subjects were enrolled for this feasibility study: 50 controls, 50 patients with RP and 50 patients without RP, according to nasal endoscopy. The ultrasound protocol was based on a ten seconds B-mode acquisition in an axial plane during normal breathing. Image processing included three steps: 1) the detection of two consecutive closing and opening images corresponding to extreme positions of vocal folds in the sequence of B-mode images; 2) the positioning of three landmarks and the robust tracking of these points using multi-pyramidal refined optical flow approaches; 3) the estimation of quantitative parameters indicating left and right fractions of mobility and motion symmetry. Results provided by the first two image processing steps were compared to those obtained by an expert. Motion symmetry and fraction of mobility indices were systematically computed using the automated procedures. Associated sensitivity and specificity values for detecting RP were then calculated. To optimize the performances of the system, a mixed CAD system, which integrates the automatic steps of image processing and a possible correction of its results by a trained operator was developed. Laryngeal ultrasound combined with appropriate image processing helped in the diagnosis of recurrent nerve paralysis and could be proposed as a first–line method

An efficient strategy based on an individualized selection of registration methods. Application to the coregistration of MR and SPECT images in neuro-oncology

International audienceAn efficient registration strategy is described that aims to help solve delicate medical imaging registration problems. It consists of running several registration methods for each dataset and selecting the best one for each specific dataset, according to an evaluation criterion. Finally, the quality of the registration results, obtained with the best method, is visually scored by an expert as excellent, correct or poor. The strategy was applied to coregister Technetium-99m Sestamibi SPECT and MRI data in the framework of a follow-up protocol in patients with high grade gliomas receiving antiangiogenic therapy. To adapt the strategy to this clinical context, a robust semi-automatic evaluation criterion based on the physiological uptake of the Sestamibi tracer was defined. A panel of eighteen multimodal registration algorithms issued from BrainVisa, SPM or AIR software environments was systematically applied to the clinical database composed of sixty-two datasets. According to the expert visual validation, this new strategy provides 85% excellent registrations, 12% correct ones and only 3% poor ones. These results compare favorably to the ones obtained by the globally most efficient registration method over the whole database, for which only 61% of excellent registration results have been reported. Thus the registration strategy in its current implementation proves to be suitable for clinical application