Cranial and vertebral osteosarcoma commonly has T2 signal heterogeneity, contrast enhancement, and osteolysis on MRI: A case series of 35 dogs

Abstract

Magnetic resonance imaging (MRI) is commonly used to evaluate the central nervous system (CNS) in dogs; however, published studies describing the MRI appearance of cranial and vertebral osteosarcoma are scarce. In this multicenter, retrospective, case series study, MRI studies of 35 dogs with cranial or vertebral osteosarcoma were prospectively scored by consensus of two veterinary radiologists. Recorded characteristics were location, signal intensity (compared to gray matter), homogeneity, contrast enhancement, margin delineation, local invasion, osteolysis, osteosclerosis, zone of transition, periosteal proliferation, pathological fracture, meningeal/CNS involvement, and presence of metastatic disease. Locations included the parietal bone (n = 1), occipital bone (n = 2), or cervical (n = 5), thoracic (n = 17), lumbar (n = 7), or sacral vertebrae (n = 3). Common features included signal heterogeneity in T2‐weighted (T2W) images (n = 35), contrast enhancement (in all 34 dogs with postcontrast MRI), osteolysis (n = 34), compression of the CNS or cauda equina (n = 33), an associated soft tissue mass (n = 33), a long zone of transition (n = 30), osteosclerosis (n = 28), signal isointensity to normal‐appearing gray matter in T1‐weighted images (T1W, n = 26), and T2W hyperintensity of adjacent brain or spinal cord (n = 23). Other findings included periosteal proliferation (n = 18), meningeal contrast enhancement (n = 17), T1W and T2W hypointense foci in the soft tissue mass (n = 14), invasion into adjacent bones (n = 10), pathological vertebral fractures (n = 7), regional lymphadenopathy (n = 6), skip metastases (n = 2), lung nodule (n = 1), diaphragmatic nodule (n = 1), and brain invasion (n = 1). Contrast enhancement was typically strong and heterogeneous. Magnetic resonance imaging features of cranial and vertebral osteosarcoma were analogous to those previously reported for other imaging modalities. Osteosarcoma should be a differential diagnosis for compressive, contrast‐enhancing, osteolytic lesions of the cranium or vertebrae.

Common Neurologic Diseases in Geriatric Dogs

“…Spinal cord tumours, as with brain neoplasms, are more commonly diagnosed in older dogs [ 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 ]. There are different classification schemes for spinal cord neoplasia.…”

“…Finally, extradural tumours are the most common spinal neoplasia in dogs, with a reported distribution of approximately 50%. The most prevalent neoplasms in this group are primary musculoskeletal, round cell neoplasia, and metastases [ 103 , 105 , 107 , 108 , 109 ].…”

“…They tend to cause chronic progressive neurological deficits, although some cases can show acute deterioration due to pathological fracture of the vertebrae secondary to bone tumours [ 103 , 107 ]. Presenting clinical signs can range from pain as a solitary sign to lameness, paresis, or even paralysis, associated most frequently with the spinal cord segment T3-L3 [ 109 , 111 ]. Pain is a commonly presenting sign with extradural or intradural extramedullary lesions, but it is also frequent in intramedullary neoplasia [ 103 , 104 , 107 , 111 ].…”

“…However, most patients with spinal cord neoplasms will require an MRI to establish the relationship of the tumour with the dura mater, involved structures, the degree of spinal cord compression, and changes in spinal cord parenchyma ( Figure 5 ) [ 103 , 107 , 108 , 109 , 111 , 113 ].…”

“…Moreover, several MRI features has been reported to try to identify different types of spinal cord extradural neoplasia [ 107 , 108 , 109 ]. However, the classification of lesions on MRI as intradural extramedullary, intramedullary, or both should be treated with caution.…”