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Chapter 7: Advanced Imaging: Spinal Surgery 75

A B

C D

Figure 7.4 These CT images were obtained in a bone algorithm (A, B) and a soft tissue algorithm (C, D) and are displayed in a bone window (A, C) and a
soft tissue window (B, D). Bony detail is best evaluated with a bone algorithm in a bone window (A) while soft tissue is best evaluated with a soft tissue
algorithm in a soft tissue window (C).

Figure 7.5 T2 myelogram image of the thoracic and lumbar
vertebral column demonstrating attenuation of the suba­
rachnoid space at the thoracolumbar junction.

images are generated. Choice and placement of the radiofrequency tion and adaptation of the protocol is possible while the scan is
coil can have a dramatic effect on image quality. The signal intensity being performed. However, there is a balance to be achieved
drops off with increasing distance from the coil so it should always between total acquisition time and diagnostic information
be placed as close to the spine as possible. For medium to large facilitating the customization of the scan protocol for the primary
breed dogs a phased array spine coil is ideal [38]. These coils have diagnostic questions. Any lesion should be evaluated in three planes
multiple adjacent individual coils with a small field of view that to provide maximum anatomical information but these do not need
when combined provide large anatomical coverage with maximum to be all in the same pulse sequence. The following is a reasonable
signal‐to‐noise ratio. For small dogs and cats a phased array cardiac minimum protocol [38–40].
or knee coil can also be used. Positioning the patient in dorsal • Sagittal T2 myelogram (heavily T2‐weighted images) (Figure 7.5).
recumbency locates the spine closest to the coil and minimizes res­ • Sagittal T2‐weighted images.
piratory motion. • Dorsal T2‐weighted images.
Many possible pulse sequences are available and their names may • Transverse T2‐weighted images through any suspected lesions
vary depending on the scanner. The ideal spine protocol would (or through each intervertebral disc if no lesion is identified).
include sufficient pulse sequences in varied anatomical planes to • Transverse T1‐weighted images before and after contrast admin­
diagnose or rule out all possible spinal diseases unless interpreta­ istration (post contrast with fat suppression).