Handheld real-time volumetric imaging of the spine: technology development

Abstract

Technical difficulties, poor image quality and reliance on pattern identifications represent some of the drawbacks of two-dimensional ultrasound imaging of spinal bone anatomy. To overcome these limitations, we sought to develop real-time volumetric imaging of the spine using a portable handheld device. The device measured 19.2 cm x 9.2 cm x 9.0 cm and imaged at 5 MHz center frequency. 2D imaging under conventional ultrasound and volumetric (3D) imaging in real time was achieved and verified by inspection using a custom spine phantom. Further device performance was assessed and revealed a 75-minute battery life and average frame rate of 17.7 Hz in volumetric imaging mode. Our results suggest that real-time volumetric imaging of the spine is a feasible technique for more intuitive visualization of the spine. These results may have important ramifications for a large array of neuraxial procedures.

Imaging Performance of a Handheld Ultrasound System With Real-Time Computer-Aided Detection of Lumbar Spine Anatomy

“…22 The bone enhancement algorithm provided 2D ultrasound images with accentuated bone surfaces and the CAD algorithm automatically detected spine anatomy within the 2D image and displayed anatomical overlays and indicators to the user.…”

“…The bright bone surfaces were mapped to the 3D model using a cost-function that maximized the similarity between the bone surfaces in the image and the 3D model. 22, 25 The cost function took the form of the following equation: $$\text{italiccost}={{\displaystyle \sum }}_{i=1}^N{\mathit{\text{min}}}_{j\in false[1,Mfalse]}\left(\frac{\mathit{\text{dist}}(\mathit{\text{model}}[i],\mathit{\text{bone}}[j])}{\mathit{\text{intensity}}(\mathit{\text{bone}}[j])}\right)$$ where N is the number of points in the 3D model, M is the number of bright bone surfaces extracted from the bone image, dist is the Euclidean distance between a model point and a bone surface, and intensity is the brightness of the bone surface. This cost function can be viewed as minimizing the distance between the observed bone surfaces and the 3D model and preferentially weighting bright bone surfaces over dim bone surfaces.…”

“…21, 22 Together, these technical solutions seek to reduce the learning curve by improving image quality and providing a secondary confirmation of the anatomical features contained within the ultrasound image. Given that ultrasound guidance is now the preferred approach for peripheral nerve blocks 23 and central lines, 24 it stands to reason that improving bone image quality may enable similarly improved efficacy for neuraxial needle guidance.…”

“…To date, however, approaches to improve ultrasound spine imaging performance have been limited to proof-of-concept demonstrations in a limited number of human subjects or phantoms. 20–22 …”

http://www.medultrason.ro/ultrasound-in-the-examination-of-the-gallbladder-a-holistic-approach-grey-scale-doppler-ceus-elastography-and-3d/

“…Real time volumetric three dimensional imaging of the spine using a hand held device has been shown to Fig 11. Skin markings prior to the neuraxial anaesthetic technique once the best image of the target has been obtained and centred in a) para-sagittal oblique view; b) transverse median view be a feasible technique in a recent study [43]. The utility of this in performing neuraxial blocks has yet to be ascertained.…”