Imaging of tumour hypoxia and metabolism in patients with head and neck squamous cell carcinoma

Figures & data

Figure 1. Good spatial overlap between [¹⁸F]FDG and [¹⁸F]HX4 uptake in a patient with a cT3N0M0 laryngeal carcinoma prior to start of radiotherapy. The interval between both scans was 8 days.

Figure 2. [¹⁸F]FDG and [¹⁸F] uptake in a patient with a cT2N2bM0 squamous cell carcinoma of the oropharynx. Even though both metastatic lymph nodes are highly [¹⁸F]FDG avid, only the lower lymph node (red arrow) also shows high [¹⁸F]HX4 PET uptake, whereas the other lymph node does not (white arrow). The interval between both scans was 5 days.

Table I. [¹⁸F]FDG and [¹⁸F]HX4 uptake parameters (mean± SD) for the primary lesions (GTVprim) and involved lymph nodes (GTVln).

		Volume GTV	[^18F]FDG				[^18F]HX4
	N		SUVmean	SUVmax	HF	HV	SUVmean	SUVmax	TMRmax	HF	HV
GTVprim average (range)	20	16 ± 12 cm^3 (2–46 cm^3)	5.1 ± 1.8 (2.7–8.9)	12.1 ± 5.7 (4.0–23.2)	51 ± 26% (8–100%)	6 ± 3 cm^3 (2–12 cm^3)	0.8 ± 0.2 (0.5–1.2)	1.2 ± 0.4 (0.6–2.0)	1.6 ± 0.4 (1.0–2.7)	9 ± 10% (0–33%)	2 ± 3 cm^3 (0–11 cm^3)
GTVln average (range)	12	21 ± 30 cm^3 (1–105 cm^3)	4.8 ± 1.9 (1.9–7.3)	9.7 ± 4.4 (2.6–15.9)	66 ± 24% (34–100%)	9.5 ± 10.7 cm^3 (1–36 cm^3)	0.9 ± 0.3 (0.5–1.3)	1.4 ± 0.5 (0.6–2.1)	1.9 ± 0.7 (1.1–2.8)	27 ± 27% (0–71%)	10 ± 14 cm^3 (0–45 cm^3)

GTV, gross tumour volume; HF, high uptake fraction; HV, high uptake volume; SUV, standardised uptake value; TMR, tumour-to-muscle ratio.

Figure 3. Correlation plots of the relationship between the gross tumour volume (GTV), FDG and HX4 uptake parameters.

Table II. Pearson's correlation coefficient (R) and corresponding p-values of the [¹⁸F]FDG and [¹⁸F]HX4 PET parameters from both the primary lesions and involved lymph nodes.

	Volume GTV	FDG SUVmean	FDG SUVmax	FDG HF	FDG HV
Volume GTV
R		0.39	0.50	0.56	0.88
p		0.03	< 0.01	< 0.001	< 0.001
HX4 SUVmean
R	0.21	0.55	0.41	0.08	0.41
p	0.25	0.001	0.02	0.67	0.02
HX4 SUVmax
R	0.39	0.56	0.54	0.31	0.46
p	0.03	< 0.001	< 0.01	0.09	< 0.01
HX4 TMRmax
R	0.62	0.61	0.59	0.42	0.66
P	< 0.001	< 0.001	< 0.001	0.02	< 0.001
HX4 HF
R	0.52	0.59	0.38	0.12	0.73
P	< 0.01	< 0.001	0.03	0.52	< 0.001
HX4 HV
R	0.87	0.41	0.36	0.25	0.93
p	< 0.001	0.02	0.05	0.16	< 0.001

GTV, gross tumour volume; HF, high uptake fraction; HV, high uptake volume; SUV, standardised uptake value; TMR, tumour-to-muscle ratio.

Figure 4. Visual representation of the overlap of [¹⁸F]FDG high fraction (blue) and [¹⁸F]HX4 high fraction (red) of the primary tumour (black) of all patients. The range of the [¹⁸F]FDG high fraction is from 8% (patient 18), to 100% (patient 6). The range of the [¹⁸F]HX4 high fraction is from 0% (Patient 4, 5, 6, 9, 14, 19 and 20) to 33% (Patient 11).