Pediatric Atypical Teratoid/Rhabdoid Tumors of the Brain: Identification of Metabolic Subgroups Using In Vivo 1H-MR Spectroscopy

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Fig 1.
T2-weighted MR imaging and MR spectra of supratentorial AT/RTs with ASCL1 expression (upper row), a posterior fossa AT/RT with ASCL1 expression (middle row), and posterior fossa AT/RT without ASCL1 expression (lower row). Cr, Cho, and mI are readily detectable in the spectra of supratentorial and posterior fossa ASCL1-expressing AT/RTs, whereas only Cho is clearly detectable in the ASCL1-nonexpressing posterior fossa AT/RT. All spectra show prominent signal from lipids and lactate (Lac). Shown are the unprocessed data (thin black lines) with the superimposed fit (thick gray lines) used for quantification. The “box” seen in the images represents the voxel placement.
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Fig 2.
K-means cluster analysis graph demonstrating the metabolic clusters based on Cr/Cho and mI/Cho ratios. Ratios were transformed to z scores for better illustration. Findings suggest that a subgroup of AT/RTs (solid line) are homogeneously characterized by very low Cr and mI levels (relative to Cho) and are well-separated from other AT/RTs. It is, however, unclear whether the remaining larger cluster of AT/RTs (dashed line) forms a single group or multiple separate groups as suggested by the molecular data.

Table 1:

Patient demographics and clinical and biologic lesion characterization

Age (yr)	Sex	Overall Survival (mo)	Location	LM	ASCL1	CKB	Germline Mutation
0.15	F	0.5^{^a}	Posterior fossa	0	Negative	5.05
0.32	F	17.0	Posterior fossa	0	Positive	6.31	Yes
0.39	M	8.2^{^b}	Posterior fossa	1	Positive
0.64	M	7.0	Parietal lobe	0	Negative	5.10
0.67	M	0.5^{^a}	Posterior fossa	1	Positive
0.68	M	5.1	Intraventricular	0	ND
0.92	F	0.5^{^a}	Posterior fossa	1	Positive		Yes
0.95	M	71.9^{^b}	Posterior fossa	0	ND
1.09	M	13.0	Posterior fossa	0	Negative	5.31
1.14	M	7.0	Temporal lobe	0	Positive	6.05	Yes
1.15	M	59.0	Posterior fossa	0	Negative	6.31
1.42	F	9.0	Posterior fossa	1	ND
1.54	M	32.0	Temporal lobe	0	Positive	6.53	Yes
1.55	M	63.2^{^b}	Posterior fossa	0	Negative
1.73	M	13.0	Pineal	0	Positive
1.84	F	18.0	Frontotemporal	0	Negative	5.21
1.96	F	NA	Temporal lobe	1	ND
2.86	M	18.0	Frontotemporal	1	Positive	6.61
7.43	F	40.0	Frontotemporal	0	Positive	6.42
13.72	M	40.0	Intraventricular	0	Positive	5.71

Note:—NA indicates patient lost to follow up; LM, leptomeningeal disease present (1) versus absent (0) at presentation; ND, not determined.
↵a Patients who died from surgical/other complications with no MR imaging or clinical evidence of progressive tumor.
↵b Patients who were still alive at the time of the completion of this study.

Table 2:

Features of AT/RTs with expression of ASCL1^{^a}

Note:—NS indicates not significant; Pos., positive; Neg., negative; PF, posterior fossa.
↵a Tissue from 16 of 20 AT/RTs was available for testing of ASCL1 status.
↵b Means in IU.
↵c Approaching significance with P = .07.