The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform

Anthony E Samir - One of the best experts on this subject based on the ideXlab platform.

  • ultrasound shear wave elastography variations of liver fibrosis assessment as a function of depth force and distance from Central Axis of the transducer with a comparison of different systems
    Ultrasound in Medicine and Biology, 2018
    Co-Authors: Manish Dhyani, Feixiang Xiang, Qian Li, Luzeng Chen, Changtian Li, Atul K Bhan, Brian W Anthony, Joseph R Grajo, Anthony E Samir
    Abstract:

    Abstract— We evaluated variation in fibrosis staging caused by depth, pre-load force and measurement off-Axis distance on different ultrasound shear wave elastography (SWE) systems prospectively in 20 patients with diffuse liver disease. Shear wave speed (SWS) was measured with transient elastography, acoustic radiation force impulse (ARFI) and 2-D shear wave elastography (SWE). ARFI and 2-D-SWE measurements were obtained at different depths (3, 5 and 7 cm), with different pre-load forces (4, 7 and 10 N and variable) and at 0, 2 and 4 cm off the Central Axis of the transducer. A single, blinded pathologist staged fibrosis using the METAVIR system (F0–F4). Area under the receiver operating characteristic curve was charted to differentiate significant fibrosis (F ≥ 2). Depth was the only factor found to influence ARFI-derived values; no acquisition factors were found to affect 2-D-SWE SWS values. ARFI and 2-D-SWE for diagnosis of significant fibrosis at a depth of 7 cm along the Central Axis had good diagnostic performance (areas under the receiver operating characteristic curve: 0.92 and 0.82, respectively), comparable to that of transient elastography. Further investigation of this finding will likely be of interest.

Wiro J Niessen - One of the best experts on this subject based on the ideXlab platform.

  • minimum cost path algorithm for coronary artery Central Axis tracking in ct images
    Medical Image Computing and Computer-Assisted Intervention, 2003
    Co-Authors: Silvia D Olabarriaga, Marcel Breeuwer, Wiro J Niessen
    Abstract:

    The quality of cardiac images acquired with multi-detector CT scanners has improved significantly, to the point where minimally invasive examination of the coronary arteries became reality. The interpretation of such images requires efficient post-processing tools to isolate the vessels from other structures, such that they can be properly analyzed quantitatively or visually. In this paper we evaluate a method for semi-automated extraction of the Central Axis of coronary arteries in these images. First the vessels are enhanced with a local filter that analyzes the main modes of second-order variation in image intensity to determine the type of local structure. Secondly, the extremities of the Axis are indicated by the user. Finally, a connected path between the given points is automatically determined with a minimum cost path algorithm, where the cost corresponds to the reciprocal of the enhanced image. The results obtained with different vessel enhancement filters are compared with manually traced axes in the evaluation of 15 cases.

  • MICCAI (2) - Minimum Cost Path Algorithm for Coronary Artery Central Axis Tracking in CT Images
    Lecture Notes in Computer Science, 2003
    Co-Authors: Silvia D Olabarriaga, Marcel Breeuwer, Wiro J Niessen
    Abstract:

    The quality of cardiac images acquired with multi-detector CT scanners has improved significantly, to the point where minimally invasive examination of the coronary arteries became reality. The interpretation of such images requires efficient post-processing tools to isolate the vessels from other structures, such that they can be properly analyzed quantitatively or visually. In this paper we evaluate a method for semi-automated extraction of the Central Axis of coronary arteries in these images. First the vessels are enhanced with a local filter that analyzes the main modes of second-order variation in image intensity to determine the type of local structure. Secondly, the extremities of the Axis are indicated by the user. Finally, a connected path between the given points is automatically determined with a minimum cost path algorithm, where the cost corresponds to the reciprocal of the enhanced image. The results obtained with different vessel enhancement filters are compared with manually traced axes in the evaluation of 15 cases.

Manish Dhyani - One of the best experts on this subject based on the ideXlab platform.

  • ultrasound shear wave elastography variations of liver fibrosis assessment as a function of depth force and distance from Central Axis of the transducer with a comparison of different systems
    Ultrasound in Medicine and Biology, 2018
    Co-Authors: Manish Dhyani, Feixiang Xiang, Qian Li, Luzeng Chen, Changtian Li, Atul K Bhan, Brian W Anthony, Joseph R Grajo, Anthony E Samir
    Abstract:

    Abstract— We evaluated variation in fibrosis staging caused by depth, pre-load force and measurement off-Axis distance on different ultrasound shear wave elastography (SWE) systems prospectively in 20 patients with diffuse liver disease. Shear wave speed (SWS) was measured with transient elastography, acoustic radiation force impulse (ARFI) and 2-D shear wave elastography (SWE). ARFI and 2-D-SWE measurements were obtained at different depths (3, 5 and 7 cm), with different pre-load forces (4, 7 and 10 N and variable) and at 0, 2 and 4 cm off the Central Axis of the transducer. A single, blinded pathologist staged fibrosis using the METAVIR system (F0–F4). Area under the receiver operating characteristic curve was charted to differentiate significant fibrosis (F ≥ 2). Depth was the only factor found to influence ARFI-derived values; no acquisition factors were found to affect 2-D-SWE SWS values. ARFI and 2-D-SWE for diagnosis of significant fibrosis at a depth of 7 cm along the Central Axis had good diagnostic performance (areas under the receiver operating characteristic curve: 0.92 and 0.82, respectively), comparable to that of transient elastography. Further investigation of this finding will likely be of interest.

Alejandro Mazal - One of the best experts on this subject based on the ideXlab platform.

  • in vivo dose verification from back projection of a transit dose measurement on the Central Axis of photon beams
    Physica Medica, 2011
    Co-Authors: P Francois, Philippe Boissard, Lucie Berger, Alejandro Mazal
    Abstract:

    Abstract Purpose In vivo dose verification is used to prevent major deviations between the prescribed dose and the dose really delivered to the patient. This work presents a quick and simple alternative method for verification of dose delivered to the patient using photon beams. During the treatment session, a transit dose is measured with the EPID and the dose in the patient is estimated from back projection of the portal dose. Methods and Materials The formalism for dose calculation is described. It is independent of the detector and has been validated for different beam energies using an ionization chamber (IC). Central Axis doses estimated by this formalism were compared with measured dose. Subsequently, the IC was replaced by the EPID appropriately calibrated. The feasibility of the method and its applicability in clinical use has been evaluated on 3 8 patients treated with conformal therapy for various localizations. Results Ratios between stated and measured doses are reported. They are within the accepted tolerance of classical in vivo dosimetry (SD of 3.5%). Conclusions The proposed method for in vivo dose verification is very simple to implement and to use in clinics. Measurements can be repeated during several sessions giving the opportunity to built new strategies for the validation by statistical evaluation of the data. The trending of in vivo dose along the treatment becomes also possible. The number of checkable beams is also increased by this method.

Silvia D Olabarriaga - One of the best experts on this subject based on the ideXlab platform.

  • minimum cost path algorithm for coronary artery Central Axis tracking in ct images
    Medical Image Computing and Computer-Assisted Intervention, 2003
    Co-Authors: Silvia D Olabarriaga, Marcel Breeuwer, Wiro J Niessen
    Abstract:

    The quality of cardiac images acquired with multi-detector CT scanners has improved significantly, to the point where minimally invasive examination of the coronary arteries became reality. The interpretation of such images requires efficient post-processing tools to isolate the vessels from other structures, such that they can be properly analyzed quantitatively or visually. In this paper we evaluate a method for semi-automated extraction of the Central Axis of coronary arteries in these images. First the vessels are enhanced with a local filter that analyzes the main modes of second-order variation in image intensity to determine the type of local structure. Secondly, the extremities of the Axis are indicated by the user. Finally, a connected path between the given points is automatically determined with a minimum cost path algorithm, where the cost corresponds to the reciprocal of the enhanced image. The results obtained with different vessel enhancement filters are compared with manually traced axes in the evaluation of 15 cases.

  • MICCAI (2) - Minimum Cost Path Algorithm for Coronary Artery Central Axis Tracking in CT Images
    Lecture Notes in Computer Science, 2003
    Co-Authors: Silvia D Olabarriaga, Marcel Breeuwer, Wiro J Niessen
    Abstract:

    The quality of cardiac images acquired with multi-detector CT scanners has improved significantly, to the point where minimally invasive examination of the coronary arteries became reality. The interpretation of such images requires efficient post-processing tools to isolate the vessels from other structures, such that they can be properly analyzed quantitatively or visually. In this paper we evaluate a method for semi-automated extraction of the Central Axis of coronary arteries in these images. First the vessels are enhanced with a local filter that analyzes the main modes of second-order variation in image intensity to determine the type of local structure. Secondly, the extremities of the Axis are indicated by the user. Finally, a connected path between the given points is automatically determined with a minimum cost path algorithm, where the cost corresponds to the reciprocal of the enhanced image. The results obtained with different vessel enhancement filters are compared with manually traced axes in the evaluation of 15 cases.