MR Imaging of Pediatric Low-Grade Gliomas: Pretherapeutic Differentiation of BRAF V600E Mutation, BRAF Fusion, and Wild-Type Tumors in Patients without Neurofibromatosis-1

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FIG 1.
A 3-year-old girl who presented with symptoms related to increased intracranial pressure. The brain MR imaging shows a large complex cystic/solid mass lesion arising from the vermis and anteriorly compressing the fourth ventricle, therefore causing supratentorial massive hydrocephalus. The solid component of the tumor shows slight hyperintense signal on T2WI (A) and diffuse enhancement (B) but not with diffusion restriction (C and D). The tissue diagnosis was pilocytic astrocytoma with KIAA1549:BRAF fusion.
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FIG 2.
A 9-year-old boy with seizures. The brain MR imaging shows an ill-defined mass lesion with tiny internal cystic changes on T2 FLAIR (A) involving the mesial aspect of the left temporal lobe. The lesion shows moderate surrounding edema, mild mass effect against surrounding structures, as well as moderate enhancement (B). On DWI (C) and ADC (D), the mass shows diffusion restriction. The final tissue diagnosis was ganglioglioma with a BRAF V600E mutation.

Table 1:

Cohort information

Table 2:

Univariate analysis of demographics and clinical characteristics by molecular group

Variables	KIAA1549:BRAF Fusion	BRAF V600E	Wild-Type/Other	P₁	P₂
Variables	No. (%)	No. (%)	No. (%)	(Fusion vs V600E vs WT)	(Fusion vs V600E)
Sex				.3583	.4436
Male	16 (53)	8 (42)	7 (33)
Female	14 (47)	11 (58)	14 (67)
Age at time of MR imaging (yr)				.0012	.0126
Median	3.3 (1.56–5.10)^{^a}	9.7 (5.08–14.25)^{^a}	10.5 (6.42–14.58)^{^a}
Progression of disease				.5769	.3669
Yes	15 (50)	12 (63)	13 (62)
No	15 (50)	7 (37)	8 (38)
WHO grade				.0902	.0724
Grade I	27 (90)	13 (68)	18 (95)
Grade II	3 (10)	6 (32)	1 (5)
Tumor location				<.0001	<.0001
Brainstem	2 (7)	1 (5)	1 (5)
Cerebral hemisphere	3 (10)	13 (68)	13 (62)
OPHG	7 (23)	4 (21)	3 (14)
Posterior fossa	17 (57)	0 (0)	4 (19)
Spinal cord	1 (3)	1 (5)	0 (0)
Metastatic status				.8107	1.0000
Yes	1 (3)	1 (5)	2 (10)
No	29 (97)	18 (95)	19 (90)