Voxelwise comparison of perfusion parameters estimated using dynamic contrast enhanced (DCE) computed tomography and DCE-magnetic resonance imaging in locally advanced cervical cancer

Figures & data

Figure 1. Parametric maps estimated by DCE-CT (top row) and the corresponding parametric maps estimated by DCE-MRI (bottom row) using the population-based AIF by Parker et al. [16].

Figure 2. Bland-Altman plots (left) and corresponding scatter plots (right) for K^trans and v_e measured by CT and MRI (using the Parker AIF [16]). The mean voxelwise differences, prediction interval and confidence interval is denoted in bold solid black, solid black and gray line, respectively.

Table I. Comparison of DCE-CT and -MRI parameter estimates. (*) significant correlation.

		K^trans (min^−1)	ve	kep (min^−1)	vp
Pt. specific AIF	CT-derived mean (± SD)	0.28 (± 0.13)	0.40 (± 0.13)	0.61 (± 0.13)	0.05 (± 0.03)
Parker AIF	MRI-derived mean (± SD)	0.40 (± 0.25)	0.50 (± 0.16)	0.82 (± 0.28)	0.03 (± 0.03)
	t-test p-value	0.003	0.01	< 0.001	0.002
	R (95% CI)	0.90 (0.73, 0.97)*	0.58 (0.11, 0.83)*	0.77 (0.44, 0.92)*	0.83 (0.56, 0.94)*
Magnitude AIF	MRI-derived mean (± SD)	0.52 (± 0.34)	0.51 (± 0.14)	0.99 (± 0.37)	0.09 (± 0.07)
	t-test p-value	0.001	0.003	< 0.001	0.005
	R (95% CI)	0.86 (0.64, 0.95)*	0.60 (0.14, 0.84)*	0.79 (0.49, 0.93)*	0.78 (0.47, 0.92)*
CT-derived AIF	MRI-derived mean (± SD)	0.47 (± 0.27)	0.60 (± 0.13)	0.76 (± 0.31)	0.06 (± 0.05)
	t-test p-value	< 0.001	< 0.001	0.002	0.08
	R (95% CI)	0.89 (0.72, 0.96)*	0.48 (−0.03, 0.79)	0.86 (0.64, 0.95)*	0.89 (0.72, 0.96)*

Table II. Interpatient variation of AIF observables.

	CT AIF			MR AIF
	Mean	SD	CV	Mean	SD	CV
Peak height[mM/ml]	0.301	0.076	25%	0.351	0.161	46%
FWHM [s]	9.55	1.98	21%	11.03	3.19	29%
SI180 [s× mM/ml]	0.030	0.011	38%	0.051	0.011	21%

CV, coefficient of variance; FWHM, full width half max; SD, standard deviation, SI₁₈₀, signal intensity 180 s after peak height.

Figure 3. Example of Γ-analysis. A Γ-value > 1 fails the set criteria while Γ-value = 0 corresponds to perfect agreement between the two measures (A) shows the Γ-value using the criteria of 3 mm distance to agreement and 5% uncertainty (B) Γ-value using the criteria of 3 mm distance to agreement and 10% uncertainty. (C) Γ-value using the criteria of 3 mm distance to agreement and 15% uncertainty. (D) Ktrans map estimated using DCE-CT. (E) Ktrans map estimated using DCE-MRI and the Parker et al. AIF [16]. (F) Γ-failure rates for the different tested criteria.

Figure 4. Box-plots for Γ-analysis comparing parametric maps derived using DCE-CT and DCE-MRI with the Parker AIF [16]. The central mark is the median, the edges of the box are the 25th and 75th percentiles, and the range of the whiskers includes 99.3 percentiles of the data. ‘+’ denotes the outliers.

Parker GJM, Roberts C, Macdonald A, Buonaccorsi GA, Cheung S, Buckley DL, et al. Experimentally-derived functional form for a population-averaged high-temporal-resolution arterial input function for dynamic contrast- enhanced MRI. Magn Reson Med 2006;56:993–1000.

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