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Biomedical subjects

Donal McNally

Publications and source records attributed to Donal McNally.

3 recordsLinked to original sources

Intraoperative pulmonary embolism of Harrington rod during spinal surgery: the potential dangers of rod cutting.

This is a case report and laboratory-based biomechanics study. The objective is to report the first case of Titanium rod embolisation during scoliosis surgery into the Pulmonary artery. To investigate the potential of an unconstrained cut Titanium rod fragment to cause wounding with reference to recognised weapons. Embolisation of a foreign body to the heart is rare. Bullet embolisation to the heart and lungs is infrequently reported in the last 80 years. Iatrogenic cases of foreign body embolisation are very rare. Fifty 1-2 cm segments of Titanium rod were cut in an unconstrained manner and a novel method was used to calculate velocity. A high-speed camera (6,000 frames/s) was used to further measure velocity and study projectile motion. The wounding potential was investigated using lambs liver, high-speed photography and local dissection. Rod velocities were measured in excess of 23 m s(-1). Rods were seen to tumble end-over-end with a maximum speed of 560 revolutions/s. The maximum kinetic energy was 0.61 J which is approximately 2% that of a crossbow. This is sufficient to cause significant liver damage. The degree of surface damage and internal disruption was influenced by the orientation of the rod fragment at impact. An unconstrained cut segment of a Titanium rod has a significant potential to wound. Precautions should be taken to avoid this potentially disastrous but preventable complication.

Adult↗

Computer vision elastography: speckle adaptive motion estimation for elastography using ultrasound sequences.

We present the development and validation of an image based speckle tracking methodology, for determining temporal two-dimensional (2-D) axial and lateral displacement and strain fields from ultrasound video streams. We refine a multiple scale region matching approach incorporating novel solutions to known speckle tracking problems. Key contributions include automatic similarity measure selection to adapt to varying speckle density, quantifying trajectory fields, and spatiotemporal elastograms. Results are validated using tissue mimicking phantoms and in vitro data, before applying them to in vivo musculoskeletal ultrasound sequences. The method presented has the potential to improve clinical knowledge of tendon pathology from carpel tunnel syndrome, inflammation from implants, sport injuries, and many others.

Algorithms↗

Ultrasound imaging of the intervertebral disc.

STUDY DESIGN: In vitro ultrasound imaging of dog intervertebral discs was performed. OBJECTIVE: To determine the reliability of ultrasound imaging in the detection of structural changes associated with disc pathology. SUMMARY OF BACKGROUND DATA: Little work has been done to evaluate the potential applications of ultrasound in the imaging of intervertebral discs. Initial in vitro studies, however, have indicated that ultrasound imaging is capable of producing images of the disc that contain a high degree of structural information. METHODS: Explanted lumbosacral discs from 13 nonchondrodystrophic dogs, mean age 5 years and 8 months, were stripped of all surrounding tissues and scanned using ultrasound before being sectioned and photographed. The ultrasound images were graded according to criteria chosen to reflect progressive stages of disc degeneration, allowing correlation with the grading scale used to assess the photographic images of the discs. Grades assigned to each disc were compared using Cronbach's alpha to determine the reliability of the images obtained using ultrasound. RESULTS: The results for the anterior anulus fibrosus produced an alpha value of 0.924; those for the nucleus pulposus produced a value of 0.821; whereas those for the posterior anulus fibrosus produced a value of 0.882. Where the grade given to the ultrasound image did not match those given in visual assessment, the disparity was never greater than one grade. Ultrasound images of several discs demonstrated echo patterns that matched, in both location and appearance, real structural defects identifiable on the sectioned discs. CONCLUSIONS: Ultrasound images of intervertebral discs relate well to their pathologic condition. In addition, ultrasound is able to locate specific pathologic defects.

Animals↗