Table 2.

Magnetic resonance imaging characteristics of the primary mass, in 10 dogs that developed cerebrospinal fluid (CSF) drop metastasis of glioma.

MRI criteria	Number of cases
T1 and T2 signals	Heterogeneous (n = 7) Foci T2-isointense to CSF (n = 7)	Homogeneous T1 and T2 (n = 2) Homogeneous T1 only (n = 3)
FLAIR signals	Hetero with extreme hyperintense (n = 5) Hetero hyperintense (n = 1)	Half isointense, half extreme hypointense (n = 1) Homogeneous (n = 2)
Gradient Echo signal voids (9 cases)	Majority of mass (n = 1) Foci (n = 2)	None (n = 6)
Perilesional edema (adjacent T2/FLAIR hyperintensity)	Pronounced (n = 1) Negligible (n = 4)	Immediately adjacent only (n = 5)
Contrast enhancement	Strong peripheral (n = 4) Strong heterogeneous (n = 3)	Small region within non-enhancing mass (n = 2) Strong homogeneous (n = 1)
Diffusion-Weighted Imaging (8 cases)	Heterogeneous without extreme hyperintense (n = 6)	Heterogeneous with extreme hyperintense (n = 2)

Extreme hyperintense: equal to signal of normal CSF on T2. Extreme hypointense: equal to signal of normal CSF on FLAIR.

FLAIR, fluid attenuation inversion recovery; Hetero, heterogeneous.