Panorama Ultrasound for Navigation and Guidance of Epidural Anesthesia

Abstract

Despite the common use of epidural anesthesia in obstetrics and surgery, the procedure can be challenging, especially for obese patients. We propose the use of an ultrasound guidance system employing a transducer-mounted camera to create 3-D panorama ultrasound volumes of the spine, thereby allowing identification of vertebrae and selection of puncture site, needle trajectory and depth of insertion. The camera achieves absolute position estimation of the transducer with respect to the patient using a specialized marker strip attached to the skin surface. The guidance system is validated first on a phantom against a commercial optical tracking system and then in vivo by comparing panorama images from human subjects against independent measurements by an experienced sonographer. The results for measuring depth to the epidural space, intervertebral spacing and registration of interspinous gaps to the skin prove the potential of the system for improving guidance of epidural anesthesia. The tracking and visualization are implemented in real time using the 3D Slicer software package.

Stitching of sensor-navigated 3D ultrasound datasets for the determination of large thyroid volumes – a phantom study

“…In contrast, the present study focused on the feasibility of stitching 3D-US datasets specifically for thyroid volumetric analysis using ad hoc-developed phantoms. Different phantoms are available for US investigations [12,14,16,17,19] and another group also recently developed a flexible balloon phantom of the thyroid that allows for the simulation of nodular shape alterations and isthmus thickening [10]. In the present study, this original model was further adapted to increase the volume range from 200 mL to 400 mL; additionally, ventral echogenic landmarks were placed to facilitate the subsequent stitching procedure, and a support rod was added with the intent of maintaining the anthropomorphic shape of the thyroid phantom and retaining a trachea dummy in place.…”

“…Orientation of 3D-US datasets before stitching can be performed automatically or semi-automatically [12,13,16,17,[19][20][21]; however, in this study, we opted for a manual approach based on the phantom landmarks, with a time span of not more than 2 min. The results show Rho*: correlation coefficient according to Bravais-Pearson analyses; 95% CI: 95% confidence interval of the mean; LOA: Limit of agreement; em: ellipsoid mode; mt: manual tracing that the manual adjustment and the stitching of separately obtained 3D-US datasets acquired via sensor-navigated probe was possible and in fact accurate.…”

Improving needle tip identification during ultrasound-guided procedures in anaesthetic practice

“…As a low‐cost solution, the Microsoft Kinect (Microsoft corporation, Redmond, WA, USA), normally used for gaming, can aid in identifying needles . Another opportunity for optical tracking is to reconstruct 3D images, for instance of the spine, to determine a desired epidural puncture site .…”

“…Higher costs and the need for direct and unobstructed vision of the probe and needle are disadvantages. We are not aware of clinical studies using optical tracking in anaesthesia, apart from imaging regions of interest .…”

Randomized comparison of two methods of the epidural space identification during regional labour analgesia

“…Lumbosacral epidural analgesia (EDA) remains the most effective way of alleviating labour pain [1], as it increases patient comfort and quality of patient-personnel cooperation during labour. The procedure involves 3 crucial steps: (i) identification of vertebrae level, (ii) selection of desired puncture site and angle, (iii) needle insertion into epidural space (EDS) between ligamentum flavum (LF) and dura mater covering a spinal cord [2].…”