Table 5. Distinction of the posttreatment recurrent or residual tumor from fibrosis/granulation tissue based on average ADC in head and neck SCC.

Study*	b values (s/mm2)	ADC threshold**	Accuracy	Sensitivity	Specificity
Abdel Razek et al. (81)	0, 1,000	1.4 ×10−3 mm2/s	87%	84%	90%
King et al. (80)	0, 100, 200, 300, 400, 500	1.3 ×10−3 mm2/s	71%	45%	100%
Vandecaveye et al. (82)	0, 1,000	1.3 ×10−3 mm2/s	95.5%	94.6%	95.9

Above studies have shown lower average ADC in residual/recurrent cancer compared to posttreatment benign tissue. *, all studies used 1.5 T scanners; **, average ADC of the posttreatment tissue. SCC, squamous cell carcinoma; ADC, apparent diffusion coefficient.