EchoFusion: Tracking and Reconstruction of Objects in 4D Freehand Ultrasound Imaging without External Trackers

Ultrasound (US) is the most widely used fetal imaging technique. However, US images have limited capture range, and suffer from view dependent artefacts such as acoustic shadows. Compounding of overlapping 3D US acquisitions into a high-resolution volume can extend the field of view and remove image artefacts, which is useful for retrospective analysis including population based studies. However, such volume reconstructions require information about relative transformations between probe positions from which the individual volumes were acquired. In prenatal US scans, the fetus can move independently from the mother, making external trackers such as electromagnetic or optical tracking unable to track the motion between probe position and the moving fetus. We provide a novel methodology for image-based tracking and volume reconstruction by combining recent advances in deep learning and simultaneous localisation and mapping (SLAM). Tracking semantics are established through the use of a Residual 3D U-Net and the output is fed to the SLAM algorithm. As a proof of concept, experiments are conducted on US volumes taken from a whole body fetal phantom, and from the heads of real fetuses. For the fetal head segmentation, we also introduce a novel weak annotation approach to minimise the required manual effort for ground truth annotation. We evaluate our method qualitatively, and quantitatively with respect to tissue discrimination accuracy and tracking robustness.Comment: MICCAI Workshop on Perinatal, Preterm and Paediatric Image analysis (PIPPI), 201

3-D measurement of body tissues based on ultrasound images with 3-D spatial information

2005-2006 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

Volume reconstruction of freehand three-dimensional ultrasound using median filters

2008-2009 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

A new adaptive interpolation algorithm for 3D ultrasound imaging with speckle reduction and edge preservation

Author name used in this publication: Qinghua HuangAuthor name used in this publication: Yongping ZhengAuthor name used in this publication: Minhua Lu2008-2009 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

Three-dimensional multimodal medical imaging system based on freehand ultrasound and structured light

We propose a three-dimensional (3D) multimodal medical imaging system that combines freehand ultrasound and structured light 3D reconstruction in a single coordinate system without requiring registration. To the best of our knowledge, these techniques have not been combined as a multimodal imaging technique. The system complements the internal 3D information acquired with ultrasound with the external surface measured with the structured light technique. Moreover, the ultrasound probe’s optical tracking for pose estimation was implemented based on a convolutional neural network. Experimental results show the system’s high accuracy and reproducibility, as well as its potential for preoperative and intraoperative applications. The experimental multimodal error, or the distance from two surfaces obtained with different modalities, was 0.12 m

Freehand Three-Dimensional Ultrasound to Evaluate Scapular Movement

Altered scapular kinematics have been linked to increases in shoulder pain and pathology. As such, identifying normal scapular movement is integral to preventing pathology and maintaining health of the joint. Existing methods to evaluate scapular movement are invasive, expensive, require exposure to radiation, suffer skin based motion artifacts, or allow for examination only in static postures. Freehand three-dimensional ultrasound offers the unique ability to image bone while being non-invasive, relatively low cost, and free of radiation. This is a novel application of a technology that in the past has been used for needle guided injections and determining changes in organ volumes, but never for evaluating bone movement. We have developed a custom freehand-ultrasound system that shows high repeatability across trials (SEM < 2°) in evaluating scapular kinematics in static postures with the arm at rest and elevated in the sagittal, frontal and scapular planes. Among manual wheelchair users and able-bodied controls we found scapular kinematics with the arm in an elevated position were predicted by scapular and trunk position at rest. We also found BMI ≥ 25, presence of pathology on a physical exam, shoulder abnormalities on a clinical ultrasound exam, and greater than 10 years of wheelchair use resulted in scapular postures associated with shoulder pathology in previous studies. We found no significant differences between wheelchair users and age-matched controls but attribute this to a lack of difference in pathology between the groups. A learning curve was identified over time for capturing quality ultrasound images and it is suggested future studies incorporate ample training time and require raters to meet minimum performance measures set forth by this study. In a subsample of subjects we found increases in external rotation, upward rotation and posterior tilting at incremental angles of humeral elevation during dynamic trials indicating that it is feasible to apply our methods to evaluate dynamic scapular movement. Application of these methods may help to identify shoulder pathology and evaluate the efficacy of interventions to correct altered scapular kinematics