Usefulness of a half-fourier acquisition single-shot turbo spin-echo pulse sequence in identifying arachnoid diverticula in dogs
Department of Molecular Biomedical Sciences, North Carolina State University, 1052 William Moore Drive, Raleigh, NC 27607, USA.Veterinary Radiology & Ultrasound (Impact Factor: 1.45). 03/2012; 53(2):157-61. DOI: 10.1111/j.1740-8261.2011.01893.x
Single-shot turbo spin-echo sequences are heavily T2-weighted sequences that are exceptionally well suited to evaluate the subarachnoid space. In the T2-weighted fast spin-echo sequences that are used routinely in spinal magnetic resonance (MR) imaging, the subarachnoid space is not well differentiated from the surrounding epidural fat, which could lead to decreased detection of lesions of the subarachnoid space such as arachnoid diverticula. Our purpose was to determine the added value of a single-shot turbo spin-echo sequence in identifying cystic lesions of the subarachnoid space in dogs. MR images of six dogs with a confirmed arachnoid diverticulum and 24 dogs with other spinal disease were included. Six observers were asked to interpret only T2-weighted images initially, and in a second session, T2-weighted and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences. The MR images were anonymized, and no signalment, history, or clinical information was provided. Without the HASTE sequences, 25% of arachnoid diverticula were identified. Adding the HASTE sequence increased the diagnosis of arachnoid diverticulum to 52.8%. The resulting difference, after adding the HASTE sequence, of 27.8% was statistically significant (P = 0.002). No false-positive diagnoses of arachnoid diverticulum were made with either sequence. Although sensitivity in this study was likely artificially low, the significantly increased detection rate of arachnoid diverticula when using HASTE imaging indicates that this sequence is a valuable addition to MR imaging protocols for the canine spine.
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ABSTRACT: Clinical features, myelography, and computed tomography imaging findings as well as neurological outcome with and without surgery in 5 pug dogs with thoracolumbar arachnoid diverticula are described. Short-term prognosis after surgical therapy may not be as good as reported for other canine breeds, since immediate postsurgical deterioration is possible. Improvement of neurological deficits beyond the presurgical status may take several months.
Article: Extramedullary Spinal Cysts in Dogs[Show abstract] [Hide abstract]
ABSTRACT: Objective To (1) synthesize the terminology used to classify extramedullary spinal cysts in dogs to clarify some of the commonly reported misconceptions, and (2) propose a classification scheme to limit confusion with terminology.Study designLiterature review.Methods An online bibliographic search was performed in January 2013 for articles relating to extramedullary spinal cysts in dogs using PubMed (http://www.pubmed.gov/) and Google Scholar (http://scholar.google.com/) databases. Only peer-reviewed clinical literature describing cystic lesions pertaining to the spinal cord and associated structures was included.ResultsFrom 1962 to 2013, 42 articles were identified; 25 (95 dogs) reported meningeal cysts, 10 (24 dogs) described 60 extradural cysts, 3 reports (18 dogs) described discal cysts or acute compressive hydrated nucleus pulposus extrusions (HNPE). Spinal cysts were categorized by location based on cross-sectional imaging as meningeal or extradural non-meningeal. Sub-classification was then performed based on surgical findings and pathology. Meningeal cysts included arachnoid diverticulae and Tarlov (perineural) cysts. Extradural non-meningeal cysts included intraspinal cysts of the vertebral joints, ligaments and discs. Discal cysts also fit this category and have been reported extensively in humans but appear rare in dogs.Conclusions Extramedullary spinal cysts should be first classified according to location with a sub-classification according to pathologic and surgical findings. Previous canine cases of discal cysts appear to represent a different disease entity and the term acute compressive HNPE is therefore preferred.
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ABSTRACT: Intradural disc herniation is a rarely reported cause of neurologic deficits in dogs and few published studies have described comparative imaging characteristics. The purpose of this retrospective cross sectional study was to describe clinical and imaging findings in a group of dogs with confirmed thoracolumbar intradural disc herniation. Included dogs were referred to one of four clinics, had acute mono/paraparesis or paraplegia, had low field magnetic resonance imaging (MRI) and/or computed tomographic myelography, and were diagnosed with thoracolumbar intradural disc herniation during surgery. Eight dogs met inclusion criteria. The prevalence of thoracolumbar intradural disc herniation amongst the total population of dogs that developed a thoracolumbar intervertebral disc herniation and that were treated with a surgical procedure was 0.5%. Five dogs were examined using low-field MRI. Lesions that were suspected to be intervertebral disc herniations were observed; however, there were no specific findings indicating that the nucleus pulposus had penetrated into the subarachnoid space or into the spinal cord parenchyma. Thus, the dogs were misdiagnosed as having a conventional intervertebral disc herniation. An intradural extramedullary disc herniation (three cases) or intramedullary disc herniation (two cases) was confirmed during surgery. By using computed tomographic myelography (CTM) for the remaining three dogs, an intradural extramedullary mass surrounded by an accumulation of contrast medium was observed and confirmed during surgery. Findings from this small sample of eight dogs indicated that CTM may be more sensitive for diagnosing canine thoracolumbar intradural disc herniation than low-field MRI.
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