Evaluation of T2‐weighted versus short‐tau inversion recovery sagittal sequences in the identification and localization of canine intervertebral disc extrusion with low‐field magnetic resonance imaging

Abstract

Sagittal T2-weighted sequences (T2-SAG) are the foundation of spinal protocols when screening for the presence of intervertebral disc extrusion. We often utilize sagittal short-tau inversion recovery sequences (STIR-SAG) as an adjunctive screening series, and experience suggests that this combined approach provides superior detection rates. We hypothesized that STIR-SAG would provide higher sensitivity than T2-SAG in the identification and localization of intervertebral disc extrusion. We further hypothesized that the parallel evaluation of paired T2-SAG and STIR-SAG series would provide a higher sensitivity than could be achieved with either independent sagittal series when viewed in isolation. This retrospective diagnostic accuracy study blindly reviewed T2-SAG and STIR-SAG sequences from dogs (n = 110) with surgically confirmed intervertebral disc extrusion. A consensus between two radiologists found no significant difference in sensitivity between T2-SAG and STIR-SAG during the identification of intervertebral disc extrusion (T2-SAG: 92.7%, STIR-SAG: 94.5%, P = 0.752). Nevertheless, STIR-SAG accurately identified intervertebral disc extrusion in 66.7% of cases where the evaluation of T2-SAG in isolation had provided a false negative diagnosis. Additionally, one radiologist found that the parallel evaluation of paired T2-SAG and STIR-SAG series provided a significantly higher sensitivity than T2-SAG in isolation, during the identification of intervertebral disc extrusion (T2-SAG: 78.2%, paired T2-SAG, and STIR-SAG: 90.9%, P = 0.017). A similar nonsignificant trend was observed when the consensus of both radiologists was taken into consideration (T2-SAG: 92.7%, paired T2-SAG, and STIR-SAG = 97.3%, P = 0.392). We therefore conclude that STIR-SAG is capable of identifying intervertebral disc extrusion that is inconspicuous in T2-SAG, and that STIR-SAG should be considered a useful adjunctive sequence during preliminary sagittal screening for intervertebral disc extrusion in low-field magnetic resonance.

ACVIMconsensus statement on diagnosis and management of acute canine thoracolumbar intervertebral disc extrusion

“…Limitations of MRI include prolonged acquisition time, 29,30 availability, and cost 31 . Standard protocols always include T2‐weighted (T2W) images and can be abbreviated to focus on sagittal sequences, 32‐34 but diagnostic accuracy suffers without transverse images 32 . The HASTE/T2* or short Tau inversion recovery (STIR) sequences might complement T2W images, 34,35 whereas inclusion of post‐contrast imaging does not improve diagnostic accuracy or treatment planning in most cases 36,37 .…”

“…Standard protocols always include T2‐weighted (T2W) images and can be abbreviated to focus on sagittal sequences, 32‐34 but diagnostic accuracy suffers without transverse images 32 . The HASTE/T2* or short Tau inversion recovery (STIR) sequences might complement T2W images, 34,35 whereas inclusion of post‐contrast imaging does not improve diagnostic accuracy or treatment planning in most cases 36,37 . It remains to be determined if half‐Fourier acquisition single‐shot turbo spin‐echo (HASTE) is complementary or additive to T2W images or only worthwhile if the T2W images do not show evidence of hyperintensity.…”

Diagnostic Imaging in Intervertebral Disc Disease

“…Ultrafast heavily T2W, short T1 inversion recovery (STIR), and gradient echo sequences (GRE, also known as T2 * or fast field echo-FFE) are also routinely acquired (Figure 4). A low-field MRI study looked at sagittal STIR images compared to sagittal T2W and found no difference (81). However, the parallel evaluation of the paired sagittal T2W and STIR series yielded a higher sensitivity than using either sagittal screening series in isolation (81).…”

“…A low-field MRI study looked at sagittal STIR images compared to sagittal T2W and found no difference (81). However, the parallel evaluation of the paired sagittal T2W and STIR series yielded a higher sensitivity than using either sagittal screening series in isolation (81). Heavily T2W images, also called "myelo-MRI" or HASTE (Half-Fourier acquisition single-shot turbo spin echo) images, can be used to highlight the cerebrospinal fluid signal and rapidly identify an area of interest (Figure 4).…”

HASTE MRI sequence findings correlate with loss of deep pain perception in dogs with thoracolumbar disc extrusion

“…By highlighting the dorsal and ventral cerebrospinal fluid (CSF) columns these sequences are useful for rapidly identifying regions of interest. Two studies have shown that they are not as reliable as T2W sagittal images for identifying the site of compression (Guillem Gallach et al., 2011 ; Housley et al., 2017 ) but are useful to highlight spinal cord swelling, and the suggestion is this may be a useful predictor of progressive ascending‐descending myelomalacia (Gilmour et al., 2017 ; da Costa et al., 2020 ). Using a similar technique, we hypothesised it may be possible to use HASTE sequences to correlate CSF attenuation and clinical severity at presentation.…”