Table 3.

Comparison of [¹⁸F]FDG uptake according to the WHO classification

Study	Thymoma vs thymic carcinoma			Statistical analysis
	Low-risk thymoma	High-risk thymoma	Thymic carcinoma
Sung et al.[6]	4.0 ± 0.42	5.6 ± 1.90**	10.5 ± 4.68*	*P < 0.001 compared with thymoma. **No difference was observed between low-risk and high-risk thymoma
Inoue et al.[11]	Early SUVmax 3.2 (1.1–5.3); delayed SUVmax 3.4 (1.8–6.4)	Early SUVmax 6.0 (2.2–12.9)*; Delayed SUVmax 7.4 (3.7–16.3)**		*P < 0.001 compared with low-risk thymoma. **P = 0.001 compared with low-risk thymoma
Luzzi et al.[10]	3.3 ± 0.5	13.5 ± 7.0*		*P < 0.01 compared with low-risk thymoma
Kumar et al.[8]	3.0 (1.7–3.9)	2.1(0.8–2.8)	7.0 (4.3–9.2) *	*P < 0.01 compared with thymoma
Shibata et al.[9]	Type A/AB, B1, B2 and B3; 3.2 ± 0.7, 4.8 ± 2.0, 3.7 ± 1.2, 5.0 ± 1.4		9.2 ± 2.4*	*P = 0.048, P = 0.007, P = 0.001, and P = 0.001 compared with type A/AB, B1, B2 and B3, respectively
Kaira et al.[12]	2.6 ± 0.9	4.3 ± 1.6**	8.9 ± 3.6*	*P < 0.01 compared with high-risk thymoma. **P < 0.01 compared with low-risk thymoma
Nakajo et al.[13]	3.05 ± 0.55	5.24 ± 2.44*		*P = 0.008 compared with low-risk thymoma
Igai et al.[14]	3.43 ± 2.19		8.15 ± 7.88*	*P = 0.0084 compared with thymoma
Terzi et al.[15]	SUVmax 4.0 ± 1.7; T/M ratio 2.0 ± 0.5	SUVmax 14.1 ± 8.3*; T/M ratio 7.8 ± 5.2**	SUVmax17.1 ± 8.5***; T/M ratio 9.6 ± 5.5***	*P = 0.005 and **P < 0.001 compared with low-risk thymoma. ***No difference was observed between low-risk and high-risk thymoma

T/M ratio is the ratio of the peak SUV of the tumor to the mean SUV of the mediastinum.