Table 2.

Correlations of ctDNA (copies/ml) values (vertical left column) with Image Metrics (horizontal rows). Note that pre-CRT absolute ctDNA values are highly correlated with several total nodal imaging metrics while week 2 and week 4 ctDNA values are correlated with several primary tumor imaging metrics.

pre-CRT absolute ctDNA values	Total nGTV Pre-CRT	Total nSubV LBV Pre-CRT	Total nSubV LADC Pre-CRT	Total nMVT50 Pre-CRT	Total nGTV Week 2	Total nSubV LBV Week 2	Total nSubV LADC Week 2	Total nMVT50 Week 2
rs	0.54	0.46	0.49	0.58	0.49	0.40	0.34	0.53
P wo FDC	0.004	0.02	0.01	0.004	0.01	0.04	0.09	0.009
P w FDC	0.016 *	0.024 *	0.016 *	0.016 *	0.016 *	0.046 *	0.09	0.016 *
Week 2 relative ctDNA values	pGTV Pre-CRT	pSubV LBV Pre-CRT	pSubV LADC Pre-CRT	pMTV50 Pre-CRT	pGTV 2wk	pSubV LBV 2wk	pSubV LADC 2wk	pMVT50 2wk
rs	−0.56			−0.58	−0.54			−0.47
P wo FDC	0.007	0.9	0.6	0.009	0.009	0.7	0.3	0.04
P w FDC	0.024 *	0.9	0.8	0.024 *	0.024 *	0.8	0.5	0.07
Week 4 Relative ctDNA values	pMean BV Pre-CRT	pMean ADC Pre-CRT	pMean SUV Pre-CRT		pMean BV 2wk	pMean ADC 2wk	pMean SUV 2wk
rs	−0.49	−0.37	−0.52		−0.42	−0.36	−0.28
P wo FDC	0.02	0.08	0.02		0.04	0.08	0.2
P w FDC	0.048 *	0.1	0.048 *		0.08	0.1	0.2

“Total n”: total nodal tumor volume; “p”: primary tumor; GTV: gross tmor volume; SubV: subvolume of tumor; LBV: low blood volume; LADC: low apparent diffusion coefficient; MTV50: metabolic tumor volume of FDG at 50% of maximum SUV; FDC: false discovery control; rs: correlation coefficient by Spearman’s rank correlation.

^*p value with FDC <0.05 was considered significant.