SCINTIGRAPHIC AND RADIOGRAPHIC APPEARANCE OF THE SACROILIAC REGION IN HORSES WITH GAIT ABNORMALITIES OR POOR PERFORMANCE

Nuclear bone scintigraphy is commonly used in the diagnosis of sacroiliac disease in horses. The aim of the present retrospective study was to determine if there was an association between radiopharmaceutical uptake pattern and radiographic appearance of the sacroiliac region in horses. Seventy-nine horses undergoing bone scintigraphy with Tc-99 m-HDP and radiography of the pelvis because of lameness or poor performance were studied. Subjective and semiquantitative methods were used to characterize and compare radiopharmaceutical uptake between horses. Ventrodorsal radiographs of the region were obtained and were evaluated. Subjectively, 70 horses (88.6%) had an abnormal uptake pattern. In nine horses, the sacroiliac region was normal (11.4%). There was no association between subjective evaluation of the scintigraphic images and semiquantitative methods. There was a significant association between radiopharmaceutical uptake and conformation (T- or Y-like form) and shape (butterfly-, wing-, leaf-, or horn-like) of the sacrum. The radiopharmaceutical uptake of the tubera sacralia was significantly higher in males (left side P =0.002, right side P =0.003). In conclusion, the conformation of the sacrum may play an important role in the scintigraphic appearance and may be the cause of increased radiopharmaceutical uptake.     

CONTRAST MEDIA ENHANCEMENT OF INTRACRANIAL LESIONS IN MAGNETIC RESONANCE IMAGING DOES NOT REFLECT HISTOPATHOLOGIC FINDINGS CONSISTENTLY

Certain magnetic resonance (MR) enhancement patterns are often considered to be associated with a specific diagnosis but experience shows that this association is not always consistent. Therefore, it is not clear how reliably contrast enhancement patterns correlate with specific tissue changes. We investigated the detailed histomorphologic findings of intracranial lesions in relation to Gadodiamide contrast enhancement in 55 lesions from 55 patients, nine cats, and 46 dogs. Lesions were divided into areas according to their contrast enhancement; therefore 81 areas resulted from the 55 lesions which were directly compared with histopathology. In 40 of 55 lesions (73%), the histomorphologic features explained the contrast enhancement pattern. In particular, vascular proliferation and dilated vessels occurred significantly more often in areas with enhancement than in areas without enhancement (P=0.044). In 15 lesions, there was no association between MR images and histologic findings. In particular, contrast enhancement was found within necrotic areas (10 areas) and ring enhancement was seen in lesions without central necrosis (five lesions). These findings imply that necrosis cannot be differentiated reliably from viable tissue based on postcontrast images. Diffusion of contrast medium within lesions and time delays after contrast medium administration probably play important roles in the presence and patterns of contrast enhancement. Thus, histologic features of lesions cannot be predicted solely by contrast enhancement patterns.     

Incidence of Spinal Compressive Lesions in Chondrodystrophic Dogs with Abnormal Recovery after Hemilaminectomy for Treatment of Thoracolumbar Disc Disease: A Prospective Magnetic Resonance Imaging Study

Objective— To investigate causes of the lack of clinical improvement after thoracolumbar disc surgery. Study Design— Case–control magnetic resonance imaging (MRI) study. Animals— Chondrodystrophic dogs with acute thoracolumbar disc disease treated by hemilaminectomy: 10 that had no short‐term clinical improvement and 12 with “normal” clinical improvement. Methods— Dogs that had surgery for treatment of intervertebral disc extrusion (2003–2008) where thoracolumbar disc disease was confirmed by MRI were evaluated to identify dogs that had lack of clinical improvement after surgery. Ten dogs with delayed recovery or clinical deterioration were reexamined with MRI and compared with 12 dogs with normal recovery and MRI reexamination after 6 weeks (control group). Results— Of 173 dogs, 10 (5.8%) had clinical deterioration within 1–10 days after surgery. In 8 dogs, residual spinal cord compression was identified on MRI. Bleeding was present in 1 dog. In 3 dogs, the cause was an incorrect approach and insufficient disc material removal. In 3 dogs, recurrence occurred at the surgical site. In 1 dog, the centrally located extruded material was shifted to the contralateral side during surgery. These 8 dogs had repeat surgery and recovery was uneventful. In 2 dogs, deterioration could not be associated with a compressive disc lesion. Hemorrhagic myelomalacia was confirmed by pathologic examination in 1 dog. The other dog recovered after 6 months of conservative management. Conclusion— Delayed postsurgical recovery or deterioration is commonly associated with newly developed and/or remaining compressive disc lesion. Clinical Relevance— We recommend early MRI reexamination to assess the postsurgical spinal canal and cord, and to plan further therapeutic measures in chondrodystrophic dogs with delayed recovery after decompressive hemilaminectomy for thoracolumbar disc disease.     

MRI FEATURES OF GASTROCNEMIUS MUSCULOTENDINOPATHY IN HERDING DOGS

Pelvic limb lameness that was localized clinically to the lateral gastrocnemius head was observed in dogs without history of trauma. The aim of this retrospective study was to describe magnetic resonance imaging (MRI) findings of this condition. Nine dogs were identified, eight Border Collies and one Australian Shepherd. They all had chronic pelvic limb lameness; no signs of joint effusion or instability were present. In MR images there was high signal intensity in the lateral head of the gastrocnemius muscle around the sesamoid bone in T2‐weighted, T2^*‐weighted, and STIR images and an iso‐ to mildly hyperintense signal in T1‐weighted images with marked contrast enhancement. The abnormal signal intensity most likely represents a myotendinous strain. The breed affiliation to Border Collies is striking, and a relation to biomechanical forces or motion pattern may be possible. Except for the dog with the most extensive lesion all dogs had an excellent outcome.     

RADIOGRAPHIC TECHNIQUE AND ANATOMY OF THE EQUINE SACROILIAC REGION

Radiography is part of evaluating horses with poor performance and pelvic limb lameness; however, the radiographic appearance of the sacroiliac region is poorly described. The goal of the present study was to describe the use of a simple technique to obtain radiographs of the sacroiliac region in the anesthetized horse and to describe the radiographic appearance of this region. Seventy-nine horses underwent radiography of the pelvis under general anesthesia in dorsal recumbency. During a 5s exposure time the horse was actively ventilated to blur the abdominal viscera, which allowed assessment of individual bone structures in 77 horses. A large variation in the shape of the sacral wings, their articulation with the transverse processes of L6, and the relation of the sacrum to the ilium were observed. Females had significantly narrower width of the sacral wings. Broad sacral wings and bony proliferations at the caudal aspect were commonly observed features and their size was highly correlated with gender. In males, caudal osteophytes were significantly larger than in females. Five horses had transitional or hemitransitional vertebrae. Radiography with the ventilation-induced blurring technique is a simple approach that results in diagnostic quality radiographs and delineation of the highly variable bone structures of the sacroiliac region.