UIA - Ultrasound Innovation Award

Ultrasound Innovation Award

Online Abstract Submission

(Author: WING HONG KWOK )

Abstract

Type: New imaging technique

Title: The Scanning Technique for Scoliosis Spine Using Water-Based Phantoms and Human Volunteers.

Disclosure Statements

My research & development of my invention is not supported by a commercial company

Abstract

Neuraxial blocks are difficult to perform in scoliosis, which involve tilting and rotation of vertebrae. Ultrasound (US) guidance may be useful. To guide the needle, US must be performed to obtain the transverse and paramedian oblique sagittal (PARA-O) images of vertebral column. The aim of the study is to investigate the scanning technique to obtain these images in scoliosis using water-based phantoms and patient volunteers. METHODS AND RESULTS: PHANTOM A - Full Spine: It was prepared by immersing a commercial spine model (T3 – sacrum) under water. The thoracic vertebrae from T3 to L1 were tilted creating a 25 degree curve. US scan were performed on water surface. Results: 1) To consistently obtain the PARA-O images of interlaminar spaces, it was essential to keep the US transducer’s long axis parallel to the line joined by the spinous processes (SP line). [Fig A-2] 2) To consistently obtain the transverse images of vertebrae, the transducer’s long axis should be maintained perpendicular to the SP line. [Fig A3] PHANTOM B-Lumbar: a 3-piece lumbar vertebrae anatomical model, which was rotated clockwise, was immersed and scanned. Results: 3) For transverse scanning of intervertebral space, if the transducer’s footprint was parallel to the water surface, right facet joint would appear deeper than the left on the US image.4) However, if the transducer was rocked to match the degree of vertebral rotation, both facet joints would appear at same depth on US image. 5) Simulated needle intervention showed that the final transducer’s rocking direction was a useful direction of needling to enter the spinal canal during offline US assisted intervention. [Fig B-3, B-4] Bilateral PARA-O scannng were then performed. The transducer was tilted to angle medially until widest interlaminar space and widest spinal canal were seen on US image. Results: 6) The degree of tilting needed from the sagittal plane was much smaller on the left side compared to the right side. 7) Simulated needle intervention showed that this final scanning plane represented the optimal needle insertion plane for real time in-plane US guided insertion. [Fig B-6, B-7] PHANTOM C-Thoracic was prepared by immersing and scanning a 3-piece thoracic vertebrae model, which was rotated clockwise. Results: 8) During PARA-O scanning, the degree of tilting of the transducer from the sagittal plane was much smaller in the left sided compared to the right side. 9) During simulated US guided epidural needle insertion (real time in plane approach), it was observed that the tilted paramedian scanning plane was again an optimal needle insertion plane. [Fig C-2] 10) During transverse scanning, both laminae would be at same depth on US image if the transducer was rocked. [Fig C-3] The final rocking direction was also found to be a useful direction to pass an epidural needle onto the lamina (paramedian approach). VOLUNTEERS: 10 volunteers with adolescent idiopathic scoliosis were recruited. A 3-step modified scanning technique (see Appendix A) was used. Further detail on findings in volunteers will be discussed during the oral presentation.

Clinical Significance

The study improved the understanding of how one can obtain the transverse and PARA-O images in scoliosis. This is important for performing US guded neruaxial block in scoliosis.

Ultrasound Equipment

Manufacturer: Sonosite

Model: M-Turbo

Probe Used

Type: Curved array

Size: 60 mm

Frequency: 5-2 MHz

Files

1. Filename: Spinal Ultrasound of Scoliosis_WH Kwok_May 2009.pdf

2. Filename: spinal ultrasound scoliosis_WH Kwok_May 2009.wmv

3. Filename: FigA2_FigA3_WH Kwok.jpg