Table 1:

Patient demographic and clinical characteristics^{^a}

	Aggressive Tumor	Nonaggressive Tumor	P Value
No.	6	10
Volume change ratio	14.4 ± 21.0 (−2.18–17.2)	0.463 ± 1.135 (−1.40–3.78)	.003
Doubling time (mo)	5.77 ± 4.03 (0.73–10.8)	NA
Age at first operation (yr)	54.3 ± 9.9	45.8 ± 24.3	.713
Location of tumor (ratio of clival chordoma to all)	3/6	8/10	.299^{^b}
Postsurgical RT radiation dose (Gy)	72.4 ± 33.5 (n = 4)	74.2 ± 10.9 (n = 7)	.927
Ratio of patients with postsurgical RT to all	4/6	9/10	.518^{^b}
Time from first operation to first follow-up MRI (mo)	62.8 ± 53.3	71.4 ± 76.2	>.99
Time between the 2 follow-up MRIs (mo)	9.1 ± 5.2	18.3 ± 12.5	.022
No. of surgical resections at first follow-up MRI	2.00 ± 0.89	1.10 ± 0.32	.056
Sex (M/F)	5:1	7:3	>.99^{^b}
Histopathology (ratio of classic chordoma to all chordomas)	6/6	5/10	.093^{^b}
Mean ADC (×10⁻³ × mm²/s)	1.055 ± 0.298 (0.78–1.37)	1.622 ± 0.139 (1.34–1.65)	<.001
Tumor volume (× 10³ × mm³)	21.2 ± 37.4 (0–60.4)	3.44 ± 2.38 (0–7.46)	.492

Note:—NA indicates not applicable.
↵a Numbers in the table represent mean ± SD. The numbers in parentheses indicate the 95% CIs.
↵b P value was calculated by the Fisher exact test because the data were categoric.