Canine cerebrospinal fluid total nucleated cell counts and cytology associations with the prevalence of magnetic resonance imaging abnormalities

Abstract

Introduction

The combination of cerebrospinal fluid (CSF) analysis and magnetic resonance imaging (MRI) are often used to investigate intracranial disease in dogs. The aim of this retrospective study was to determine if the total nucleated cell count (TNCC) or cytology findings in abnormal CSF are associated with the prevalence of MRI abnormalities.

Materials and methods

For each case, the TNCC was categorized into one of three groups: A (<25×10⁶/L); B (25–100×10⁶/L); and C (>100×10⁶/L). Cytology findings were categorized by the predominant cell type as lymphocytic, monocytoid, neutrophilic, or eosinopilic. MRI descriptions were classified as either normal or abnormal, and abnormal studies were further evaluated for the presence of specific characteristics (multifocal or diffuse disease versus focal disease, positive T2-weighted hyperintensity, positive FLAIR hyperintensity, contrast enhancement, mass effect, and the presence of poorly or well-defined lesion margins).

Results

Forty-five dogs met the inclusion criteria and MRI abnormalities were found in 29/45 (64%) dogs. TNCCs were not associated with the prevalence of MRI abnormalities or specific characteristics. Cytology categories were significantly associated with the prevalence of MRI abnormalities (P<0.001). Specifically, monocytoid cytology was 22.8 times more likely to have an abnormal MRI than lymphocytic cytology. CSF cytology was not significantly associated with specific abnormal MRI characteristics.

Conclusion

There are minimal associations between CSF abnormalities and the prevalence of MRI abnormalities. These results support the continued importance of utilizing both tests when investigating intracranial disease. When CSF analysis must be performed initially, this study has demonstrated that an abnormal CSF with a monocytoid cytology supports the value of performing a brain MRI in dogs with evidence of intracranial neurological disease.

Keywords:

• cerebrospinal fluid
• magnetic resonance imaging
• canine
• total nucleated cell counts
• cytology

Acknowledgments

Thank you to the Medicine Department of Veterinary Specialist Services in Brisbane, Australia, and to Dr Navneet Dhand of Sydney University for performing the statistical calculations.

Disclosure

The authors report no conflicts of interest in this work.

Supplementary materials

Table S1 Summary of CSF TNCC, cytology, and protein concentrations for all patients with normal MRI studies

Table S2 Summary of CSF TNCC, cytology, protein concentration, and MRI findings for all patients with abnormal MRI studies

Table S3 MRI findings for each total nucleated cell count group

Table S4 Incidence of specific abnormal MRI characteristics for each total nucleated cell count group

Table S5 MRI findings for each pleocytosis category

Table S6 Incidence of specific abnormal MRI characteristics for each pleocytosis category