Agreement between low-field MRI and CT for the detection of suspected intracranial lesions in dogs and cats.

OBJECTIVE: To assess the agreement between CT and MRI for enabling detection of intracranial lesions in cats and dogs. DESIGN: Evaluation study. ANIMALS: 51 dogs and 7 cats with suspected intracranial lesions. PROCEDURES: During a 2-year-period, dogs and cats with suspected intracranial pathological changes underwent MRI and CT (single slice) of the head. Radiologists evaluated images produced with both techniques without awareness of subject identity. Agreement between methods was assessed for allowing detection of solitary or multiple lesions, selected lesion characteristics (via the Cohen κ statistic), and lesion dimensions (via Bland-Altman plots). RESULTS: CT and MRI had substantial agreement for allowing detection of lesions and identification of whether the lesions were solitary or multiple. The techniques agreed almost perfectly for allowing identification of a mass effect and contrast medium enhancement, which were considered principal diagnostic imaging signs. A lower degree of agreement was attained for allowing identification of enhancement patterns and aspects of lesion margins. Agreement was substantial to almost perfect for lesion visualization in most anatomic brain regions but poor for identification of lesion dimensions. CONCLUSIONS AND CLINICAL RELEVANCE: Degrees of agreement between CT and MRI for allowing the detection and characterization of intracranial lesions ranged from poor to almost perfect, depending on the variable assessed. More investigation is needed into the relative analytic sensitivity and possible complementarities of CT and MRI in the detection of suspected intracranial lesions in dogs and cats.

Serial MRI and CSF analysis in a dog treated with intrathecal amphotericin B for protothecosis.

A 3 yr old female spayed English setter mixed-breed dog presented with diarrhea, weight loss, side stepping to the right, and a right head tilt. Rectal and cerebrospinal fluid cytology and culture confirmed a diagnosis of Prototheca zopfii. MRI of the brain showed inflammation of the brain and meninges, ventriculomegaly, and syringomyelia. Treatment with prednisone, itraconazole, and amphotericin B lipid complex administered intrathecally yielded transient improvement. Progressive brainstem signs were noted, and a repeat MRI and cerebrospinal fluid analysis documented persistent disease. This is the first description of the MRI findings and treatment with intrathecal amphoteracin B lipid complex for protothecosis of the central nervous system. Protothecosis should be considered in dogs with chronic diarrhea and compatible MRI findings.