Automated Processing of Dynamic Contrast-Enhanced MRI: Correlation of Advanced Pharmacokinetic Metrics with Tumor Grade in Pediatric Brain Tumors

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Fig 1.
A 17-year-old girl with an anaplastic grade III ependymoma is shown. In addition to axial T2-weighted and axial postcontrast T1-weighted images, corresponding maps shown are ADC, IAUGC₆₀, K^trans, K_ep, V_e, and V_p. Axial T2 image demonstrates heterogeneous tumor in the left frontal lobe with regions of hypointensity. Axial T1 postcontrast image demonstrates heterogeneous enhancement. ADC image demonstrates regions of restricted diffusion within the tumor. High K^trans and K_ep are readily apparent in the overlaid color maps, and V_e is low.
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Fig 2.
A 3-year-old boy with posterior fossa pilocytic astrocytoma is shown. Axial T2 image shows a T2 hyperintense mass in the vermis, which shows enhancement and increased diffusion. Permeability images show that though there is marked enhancement typical of these tumors, K^trans and K_ep are considerably lower, whereas V_e is higher throughout the tumor compared with the high-grade tumor shown in Fig 1.

Table 1:

Summary of model permeability parameters for all imaging measures compared between high- and low-grade pediatric tumors

Parameter	Regression Coefficient	95% CI	Standard Error	P Value	Wald Statistic
K^trans	1.54	(0.69–2.39)	0.42	<.001	13.42
K_ep	10.22	(6.12–14.33)	2.02	<.001	25.54
V_e	−0.11	(−0.15 to −0.06)	0.02	<.001	21.85
IAUGC₆₀				.12
V_p				.4
T₁₀				.34

Table 2:

Summary statistics, sensitivity, and specificity of permeability parameters statistically correlated with tumor grade

Parameter	Median	95% CI for Median	Sensitivity	Specificity
K^trans	L: 0.09	(0.06–0.13)	70%–72%	90%–100%
	H: 0.89	(0.57–1.85)
K_ep	L: 0.66	(0.33–0.97)	70%–72%	100%
	H: 6.76	(4.99–13.95)
V_e	L: 0.23	(0.19–0.26)	75%–78%	82%–100%
	H: 0.12	(0.11–0.15)