A Prognostic Model Based on Preoperative MRI Predicts Overall Survival in Patients with Diffuse Gliomas

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Fig 1.
Kaplan-Meier survival curves of 126 diffuse gliomas show overall survival to be concordant with histologic grade. Low-grade gliomas had the longest overall survival, followed by grade III and IV tumors.
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Fig 2.
Kaplan-Meier survival curves of 126 patients with diffuse gliomas. Survival curves are plotted according to the classification based on median rCBV values. Relative cerebral blood volume has a significant influence on overall survival, with a median survival of 11 months for tumors with perfusion values lower than the median rCBV.
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Fig 3.
Overall survival calculated by using Kaplan-Meier curves for all patients stratified by median ADC values. Apparent diffusion coefficient has a significant influence on survival, even better than rCBV. In our series, the median survival for diffuse gliomas with ADC values lower than 0.799 × 10⁻³ mm²/s was <12 months.

Table 1:

Histopathologic diagnosis distributed by tumor grade

Histology	Grade II	Grade III	Grade IV	Total
Astrocytomas	15 (11.9%)	7 (5.6%)	73 (57.9%) (GBM)	95 (75.4%)
Oligodendrogliomas	8 (6.3%)	10 (7.9%)		18 (14.2%)
Oligoastrocytomas	3 (2.4%)	3 (2.4%)	7 (5.6%) (GBM-O)	13 (10.4%)
Total	26 (20.6%)	20 (15.9%)	80 (63.5%)	126 (100%)

Note:—GBM indicates glioblastoma multiforme; GBM-O, glioblastoma with oligoastrocytoma grade IV.

Table 2:

Treatment of patients classified by histologic grade, rCBV, and ADC values

Histologic Grade	No Adjuvant Therapy	Radiotherapy	Chemotherapy (TMZ)	Chemoradiotherapy	Total
Grade II	7 (5.6%)	2 (1.6%)	14 (11.2%)	7 (5.6%)	24%
Grade III	1 (0.8%)	0 (0%)	6 (4.8%)	11 (8.8%)	14.4%
Grade IV	13 (10.4%)	0 (0%)	2 (1.6%)	63 (49.6%)	61.6%
Total	16.8%	1.6%	17.6%	64%	100%
rCBV values
rCBV ≥ 5.195	11 (8.7%)	0 (0.0%)	4 (3.2%)	48 (38.1%)	50%
rCBV < 5.195	11 (8.7%)	2 (1.6%)	18 (14.3%)	32 (25.4%)	50%
Total	17.5%	1.6%	17.5%	63.5%	100%
ADC values
ADC < 0.799 × 10⁻³ mm²/s	13 (10.3%)	0 (0.0%)	3 (2.3%)	47 (37.4%)	50%
ADC ≥ 0.799 × 10⁻³ mm²/s	8 (6.4%)	2 (1.6%)	19 (15%)	34 (27%)	50%
Total	16.7%	1.6%	17.3%	64.4%	100%

Table 3:

Salvage therapy classified by histologic grade, ADC and rCBV values

Table 4:

Summary of univariate associations with survival in the whole series

Prognostic Factor	Univariate Analysis
Prognostic Factor	Hazard Ratio	95% CI	P Value
Patient age	1.062	1.042–1.082	<.001
rCBV median ≥ 5.195	2.238	1.419–3.531	.001
ADC median < 0.799 × 10⁻³ mm²/s	4.766	2.882–7.883	<.0001
Histologic grade (ref grade II)			<.0001
Grade III	2.411	0.838–6.934	.0103
Grade IV	7.611	3.418–16.944	<.0001

Table 5:

Median overall survival for histologic grades classified according to the rCBV and ADC values

Note:— – indicates that at the end of follow-up, patients had not reached median overall survival.

Table 6:

Summary of multivariate associations with survival in the whole series (n = 126)

Prognostic Factor	Multivariate Analysis
Prognostic Factor	Hazard Ratio	95% CI	P Value
Patient age	1.054	1.031–1.077	<.001
rCBV median ≥ 5.195	1.608	0.928–2.784	.090
ADC median < 0.799 × 10⁻³ mm²/s	2.339	1.291–4.240	.005
Histologic grade (ref grade II)			.027
Grade III	1.484	0.495–4.449	.481
Grade IV	3.538	1.328–9.427	.012

Table 7:

Comparison of predictive performance of different Cox survival models built with prognostic factors obtained pre- and postoperatively

Prognostic Models	Harrell C	95% CI	Somers D	95% CI
Preoperative (age, rCBV median ≥ 5.195, ADC median < 0.799 × 10⁻³ mm²/s)	0.77	0.71–0.83	0.61	0.45–0.77
Postoperative (age, rCBV median ≥ 5.195, ADC median < 0.799 × 10⁻³ mm²/s, histologic grade)	0.78	0.72–0.84	0.64	0.48–0.81
Histologic grade	0.67	0.61–0.73	0.35	0.22–0.48