Perfusion in MUE.

JVIM 2024

Léa Arti, Kirsten Gnirs, Stella Papageorgiou, Yannick Ruel, Albert Agoulon, Nathalie Boddaert, Hugues Gaillot

Background
Meningoencephalitis of unknown origin (MUO) is an immune-mediated, non-infectious inflammatory disease affecting the canine central nervous system (CNS). Diagnosis is based on clinical signs, imaging, and cerebrospinal fluid (CSF) analysis. This study investigated the utility of arterial spin labeling (ASL) magnetic resonance imaging (MRI), a non-invasive perfusion imaging technique, in identifying brain perfusion changes associated with MUO, monitoring treatment responses, and predicting outcomes.

Methods
This prospective observational study involved 31 dogs with presumptive MUO. All dogs underwent brain MRI with ASL imaging before and after at least three months of immunosuppressive treatment. Perfusion changes were analyzed visually and quantitatively using cerebral blood flow (CBF) measurements. Data on lesion distribution, progression, and clinical outcomes were collected and analyzed.

Results
Initial Findings: At presentation, 33% of dogs exhibited focal brain perfusion abnormalities, and 67% showed global hypoperfusion. Most lesions localized to the optic nerves and brainstem.

Post-Treatment: All focal and global perfusion changes resolved in surviving dogs after treatment. Clinical improvement paralleled these imaging findings.

Utility of ASL: ASL imaging detected both focal and global perfusion changes but did not enhance diagnostic sensitivity compared to conventional MRI. It failed to predict prognosis reliably.

Lesion Characteristics: T2-weighted hyperintensities were common, with 85% showing T1-weighted hypointensity. Optic nerve involvement was identified in 39% of cases.

Limitations
The lack of histopathological confirmation limits differentiation among MUO subtypes.
Small sample sizes for certain subgroups may have affected statistical power.
Technical challenges, such as artifacts from microchip placements, interfered with ASL imaging in some dogs.

Conclusions
ASL imaging offers valuable insight into the perfusion characteristics of MUO and could serve as a non-invasive tool for monitoring treatment response. However, its prognostic utility is limited. Further research with histopathological correlation and larger cohorts is needed to refine its role in diagnosing and managing MUO.

MRI in a 9-year-old male Maltese with a diagnosis of MUO, at disease onset (A-D) and after 6 months of medical treatment (E-H),
including transverse T1W images (A, E) and ASL CBF maps (B, F) at the level of the cranial mesencephalon, and dorsal FLAIR images (C, G) and
reconstructed dorsal ASL CBF maps (D, H) at the level of the mesencephalic aqueduct. All ASL CBF maps (B, D, F, H) are displayed with the same
window settings (level, 40 mL/100 g/min; width, 70 mL/100 g/min). (A, C) At disease onset, there are large ill-defined heterogeneous T1W
hypointense and FLAIR hyperintense lesions within the left forebrain (green asterisks) and midbrain (red asterisks) associated with features of
increased intracranial pressure (left lateral ventricle compression, rightwards midline shift, cortical sulci collapse bilaterally). (B, D) Global brain
hypoperfusion indicated by a low ASL signal in the parietal, frontal and temporal cortex (yellow arrows) and thalamico-mesencephalic nuclei
(white arrows) bilaterally. (E, G) After 6 months of medical treatment, the left-sided forebrain and midbrain lesions have nearly resolved and all
features of increased intracranial pressure are no longer present. (F, H) Marked increase in global brain perfusion compared with the pretreatment ASL perfusion study (B, D). Mean absolute CBF measured in different normal-appearing brain regions (white and yellow arrows) has
increased by 50% to 170% after treatment. Note that all images obtained in a transverse or dorsal plane are displayed with the right side of
the dog on the left side of the image and the left side of the dog on the right side of the image. ASL, arterial spin labeling; CBF, cerebral blood
flow; FLAIR, fluid-attenuated inversion recovery; MRI, magnetic resonance imaging; MUO, meningoencephalitis of unknown origin; T1W,
T1-weighted

How did we do?

Login or Subscribe to participate in polls.

Disclaimer: The summary generated in this email was created by an AI large language model. Therefore errors may occur. Reading the article is the best way to understand the scholarly work. The figure presented here remains the property of the publisher or author and subject to the applicable copyright agreement. It is reproduced here as an educational work. If you have any questions or concerns about the work presented here, reply to this email.