Cine balanced fast field echo magnetic resonance imaging of canine spinal arachnoid diverticulae pulsation

Canine spinal arachnoid diverticulae (SAD) are characterised by focal cerebrospinal fluid dilatations within the subarachnoid space, most commonly associated with nonpainful paresis and ataxia secondary to chronic compressive myelopathy. Numerous imaging techniques have been described for diagnosis of this condition, including myelography, computed tomography myelography, and magnetic resonance imaging (MRI). The present retrospective study investigated the utility of cine balanced fast field echo (cine bFFE) MRI sequences in measuring pulsatile flow in 12 dogs with SAD. The secondary aim was to determine the prevalence and location of syringes in relation to SAD, as the co-occurrence of these conditions has not been previously reported. The degree of SAD pulsation was calculated as the change in area per cardiac cycle on sagittal (n = 12/12) and transverse (n = 7/12) cardiac-gated cine bFFE MRI sequences. Pulsation was identified on all sequences, with a median ratio of change in SAD area of 0.14 (range, 0.10-0.27; n = 12) on sagittal cine bFFE and 0.23 (range, 0.05-0.53; n = 7) on transverse cine bFFE sequences. Significant differences between minimum and maximum SAD dimensions were identified on sagittal (P = 0.002) and transverse measurements (P = 0.018). A moderate prevalence of syringomyelia was identified (n = 6/12; 50%) on T2W sequences, occurring both cranial (n = 4/12; 33%) and caudal (n = 2/12; 17%) to the SAD. These results support the ability of cine bFFE sequences to identify dynamic pulsation of canine SAD. This technique is currently limited by banding artifacts and its inability to quantify flow velocity and abnormal flow jets.