Impaired bone quality characterized by apatite orientation under stress shielding following fixing of a fracture of the radius with a 3D printed Ti-6Al-4V custom-made bone plate in dogs

Custom-made implants have recently gained attention in veterinary medicine because of their ability to properly fit animal bones having a wide variety of shapes and sizes. The effect of custom-made implants on bone soundness and the regeneration process is not yet clear. We fabricated a 3D printed Ti-6Al-4V custom-made bone plate that fits the shape of the dog radius, and placed it into the radius where an osteotomy had been made. The preferential orientation of the apatite c-axis contributes to the mechanical integrity of the bone and is a reliable measure of bone quality. We determined this parameter as well as the bone shape and bone mineral density (BMD). The bone portion which lies parallel to the bone plate exhibited bone resorption, decreased BMD, and significant degradation of apatite orientation, relative to the portion outside the plate, at 7 months after the operation. This demonstrates the presence of stress shielding in which applied stress is not transmitted to bone due to the insertion of a stiff bone plate. This reduced stress condition clearly influences the bone regeneration process. The apatite orientation in the regenerated site remained different even after 7 months of regeneration, indicating insufficient mechanical function in the regenerated portion. This is the first study in which the apatite orientation and BMD of the radius were evaluated under conditions of stress shielding in dogs. Our results suggest that assessment of bone repair by radiography can indicate the degree of restoration of BMD, but not the apatite orientation.Impaired bone quality characterized by apatite orientation under stress shielding following fixing of a fracture of the radius with a 3D printed Ti-6Al-4V custom-made bone plate in dogs. Keiichiro Mie et al. PLOS ONE. 2020. 9(2) doi.org/10.1371/journal.pone.023767

MRI findings, including diffusion-weighted imaging and apparent diffusion coefficient value, in two cats with nasopharyngeal polyps and one cat with lymphoma

Objectives Most nasopharyngeal masses in cats are lymphomas or polyps. To our knowledge, there is no report of MRI findings, including diffusion-weighted imaging (DWI) or apparent diffusion coefficient (ADC) values, of nasopharyngeal lymphomas and nasopharyngeal polyps in cats. This study aimed to evaluate the MRI findings of nasopharyngeal lymphomas and nasopharyngeal polyps, including DWI and ADC values. Methods MRI examination was performed on two cats with a histologically confirmed nasopharyngeal polyp and one cat with lymphoma. The magnetic resonance scanning protocol included T2-weighted imaging (T2WI), T1-weighted imaging (T1WI) and DWI. An ADC map was created based on DWI. ADC values were then calculated. Results MRI of the nasopharyngeal polyps revealed well-defined masses with strong rim enhancement, mass-associated stalk-like structures and asymmetric tympanic bulla lesions. The polyps appeared hyperintense on T2WI, hypo- to isointense on T1WI, and of mixed intensity or hypointense on DWI. On the ADC map, the masses appeared hyperintense. The ADC values of the polyps were 2.07 × 10 −3 mm 2 /s and 2.28 × 10 −3 mm 2 /s. MRI examination of the nasopharyngeal lymphoma revealed a strongly enhancing heterogeneous lesion. The mass appeared mildly hyperintense on T2WI, isointense on T1WI and hyperintense on DWI. On the ADC map, the mass appeared hypointense. The ADC value of the mass was 0.46 ×10 −3 mm 2 /s. The ADC values of the nasopharyngeal polyps were higher than the ADC value of the nasopharyngeal lymphoma. Conclusions and relevance Measurement of ADC values may be useful for differentiating between nasopharyngeal polyps and nasopharyngeal lymphomas

Computed tomography may detect liver infiltration of canine diffuse hepatic lymphoma

[Background] In dogs, hepatic lymphoma is characterized by neoplastic lymphocyte infiltration into the liver. Reports on the computed tomography (CT) findings of the liver for canine hepatic lymphoma are few, with only one study of multiple liver lesions type. [Objectives] The purpose of this study was to retrospectively assess the CT findings of the liver in canine diffuse hepatic lymphoma. [Methods] As control, five dogs without abnormalities in the liver were included. CT data were analysed, and the following were noted: presence of edge bluntness of the liver, presence of periportal collar sign, the liver size:body weight (BW) ratio and the mean attenuation of liver lesions on pre-contrast, arterial-phase, portal-phase and equilibrium-phase post-contrast images. [Results] On CT examination, edge bluntness of the liver was significantly detected in lymphoma (4/5, 80%), as opposed to the control (0/5, 0%) (p = 0.048, φ = 0.82). The periportal collar sign was detected in lymphoma (3/5, 60%), as opposed to the control (0/5, 0%) (p = 0.17, φ = 0.65). The liver size:BW ratio of lymphoma cases was significantly higher compared to that of the control cases (p = 0.0002, r = 0.92). The mean Hounsfield unit of lymphoma cases in the pre-contrast, arterial-phase, portal-phase and equilibrium-phase images were significantly lower than in the control cases (p = 0.005, r = 0.81; p = 0.0003, r = 0.91; p = 0.01, r = 0.75 and p = 0.02, r = 0.71, respectively). [Conclusions] Hepatic lymphoma should be a differential for a blunted and enlarged liver with hypoattenuation on CT examination

Apparent diffusion coefficient value for a B-cell central nervous system lymphoma in a cat

Case summary This report involves a 10-year-old male mixed-breed cat with a B-cell central nervous system (CNS) lymphoma. The cat presented with ataxia progressing to left hemiparesis. While haematological findings were normal, serum biochemistry showed a high creatine phosphokinase concentration. MRI revealed a homogeneously enhancing well-demarcated extra-axial lesion involving the region of the left lateral aperture with oedema in left flocculus and left medulla oblongata. On diffusion-weighted imaging, the lesion margins showed marked hyperintensity relative to the right cerebellar hemisphere. On an apparent diffusion coefficient map, the lesion appeared hypointense, with an apparent diffusion coefficient value of 0.57 ± 0.01 × 10 −3 mm 2 /s. Cerebrospinal fluid (CSF) analysis and cytology, and genetic analysis of CSF lymphoblasts confirmed a diagnosis of B-cell lymphoma. The owner opted for palliative treatment with prednisolone (1 mg/kg q12h); however, the cat died of dyspnoea 10 days after presentation. Relevance and novel information CNS lymphomas, which are the second most common intracranial tumours in cats, are highly infiltrative lesions and radical surgical excision is not recommended. Therefore, accurate diagnosis is crucial. However, contrast-enhanced MRI cannot always differentiate these lesions from other conditions, including other CNS tumours and strokes. To the best of our knowledge, this is the first report to document the diffusion-weighted imaging features and apparent diffusion coefficient value for a feline CNS lymphoma. These findings are expected to improve the diagnostic accuracy of these lesions in cats