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Towards standardized acquisition with a dual-probe ultrasound robot for fetal imaging
Towards standardized acquisition with a dual-probe ultrasound robot for fetal imaging
REVIEWED BY Caterina Watson, AFASA | ASA SIG: Emerging Technology
REFERENCE | Housden J, Wang S, Bao X, Zheng J, Skelton E, Matthew J, Noh Y, Eltiraifi O, Singh A, Singh D, Rhode K
WHY THE STUDY WAS PERFORMED
This paper summarises developments of a novel dual-probe ultrasound robot for a project called intelligent Fetal Imaging and Diagnosis (iFIND). The project aims to improve the accuracy of routine anatomy survey in pregnancy by incorporating computer-guided ultrasound technologies using multiple probes. Fetal anomaly screening would be remodelled with the assistance of robotics and AI. The motivation for this work came from evidence of reduced accuracy and sensitivity of conventional ultrasound from technical restraints, and hospital-specific variation in prenatal detection rates of major anomalies.
The design and implementation of iFIND-v3 are presented in this paper.
HOW THE STUDY WAS PERFORMED
The workflow is explained in detail followed by simulation and volunteer experiments. The workflow includes an abdominal surface mapping step, a rule-based end point calculation method to position each individual robotic joint, and a motor synchronisation method to achieve a smooth motion towards a target point.
iFIND-v3 has 17 degrees of freedom, with two arms simultaneously holding and controlling two ultrasound probes. Probe control needs to be executed avoiding collision of the arms and maintaining a safe offset distance of the robot from the patient’s abdomen. Because the shape of the abdomen will vary between patients, and at different gestations, motion planning calculations become crucial for safe robotic scanning.
Robotic design has been steered by subject feedback to reduce concerns of claustrophobia. iFIND-v3 uses a side mounted gantry over the patient with the two robotic arms attached towards the feet of the patient.
Researchers demonstrated reliable performance in controlling the robot to move towards the expected scanning area. The volunteer study demonstrated reliable acquisition of desired ultrasound views.
Of the images with ‘good’ or ‘acceptable’ quality scores, the sonographer achieved a good image in 60%, while the robot achieved this in 40% of images.
WHAT THE STUDY FOUND
The reachable percentage of abdominal surface ranged between 43–27%, located in the central abdominal region. The percentage depended on the initial configuration of the probe pairs being transverse, sagittal or oblique (see Figure 9 in paper). The areas of the abdomen missed are right and left lateral aspects, and the right and left groin. In a third trimester gestation, this area would typically be where the fetal head lies.
iFIND-v3 has only been tested for abdominal scanning in non-pregnant volunteers, producing good images of the standard views of the aorta, pancreas, liver, right lobe of liver with right kidney, gallbladder, and aorta. The kidneys were not imaged individually as they occupy a lateral position but imaged through the acoustic window of the right lobe of liver.
A sonographer assigned image quality to ‘good’, ‘acceptable’, or ‘poor’ using the British Medical Ultrasound Society Peer Review Audit Tool 2014 v3. ‘Of the images with ‘good’ or ‘acceptable’ quality scores, the sonographer achieved a good image in 60%, while the robot achieved this in 40% of images.
RELEVANCE TO CLINICAL PRACTICE
Currently, none. This work has the potential to address the standardisation of manual manipulation of hand-held probes, eliminating difficulties of maintaining accurate probe positioning for long periods of time, and the requirement for experienced sonographers to be on-site. Sonographers may experience improved mental health and reduced MSK injury from the proposed workflow. Robotic scanning may also contribute to better fetal health outcomes.
