Early prediction of pathological response in locally advanced rectal cancer based on sequential ¹⁸F-FDG PET

Figures & data

Table I. Patients' characteristics.

Parameter	Number of patients (%)
Gender
Male	18 (64)
Female	10 (36)
Age
Range	44–81
Median	67
TNM Stage
T1	0 (0)
T2	1 (4)
T3	24 (85)
T4	3 (11)
N0	4 (14)
N1	8 (29)
N2	16 (57)
M0	28 (100)
M1	0 (0)
TRG status
1	6 (21)
2	6 (21)
3	9 (33)
4	6 (21)
5	1 (4)

Figure 1. Illustration of the baseline scan (on the left) and the scan at 2 weeks (PET3, on the right) for (A) a responder and (B) a non-responder. The green contour is the FLAB delineation.

Table II. Baseline values and evolution (RIs) of each PET derived parameter with respect to baseline values.

Parameter	Baseline value median ± SD (mean, min, max)	RI2 (%) median ± SD (mean, min, max)	RI3 (%) median ± SD (mean, min, max)
SUVmax	13.9 ± 5.2 (14.9, 6.6, 26.7)	−18 ± 39 (−12, −63, +155)	−32 ± 25 (−31, −73, +47)
SUVmax^PVC	21.2 ± 9.7 (23.8, 10.2, 49.3)	−20 ± 41 (−15, −59, +165)	−43 ± 27 (−38, −75, +47)
SUVmean	7.8 ± 2.8 (8.0, 3.7, 13.9)	−20 ± 36 (−11, −59, +138)	−29 ± 25 (−28, −66, +54)
SUVmean^PVC	10.2 ± 4.0 (10.3, 4.5, 20.8)	−22 ± 37 (−12, −56, +153)	−28 ± 24 (−29, −67, +42)
MATV	23 ± 79 (49, 2, 397)	−18 ± 22 (−15, −51, +51)	−36 ± 29 (−32, −80, +42)
MATV^PVC	19 ± 76 (45, 2, 378)	−15 ± 22 (−15, −51, +39)	−32 ± 28 (−32, −78, +37)
TLG	181 ± 473 (345, 10, 2235)	−35 ± 45 (−22, −75, +137)	−57 ± 37 (−48, −86, +68)
TLG^PVC	196 ± 518 (379, 13, 2385)	−34 ± 41 (−24, −75, +130)	−59 ± 33 (−50, −88, +51)

Table III. Predictive value of each parameter baseline values and RIs using ROCs analysis. Only parameters for which a significant correlation was found [see appendix, to be found online, at http://www.informahealthcare.com/doi/abs/10.3109/0284186X.2012.702923] are included.

Parameter*		AUC	Cut-off value	Sensitivity (%)	Specificity (%)	Sensitivity for 100% specificity (%)	Cut-off value
SUVmax	RI3 (%)	0.77	−43	88	58	31	−16
SUVmax^PVC	RI3 (%)	0.73	−33	50	83	13	−5
SUVmean	PET1	0.75	6.1	50	100	50	6.1
	RI2 (%)	0.73	−31	88	33	50	−10
	RI3 (%)	0.79	−34	81	67	31	−11
SUVmean^PVC	PET1	0.76	7.3	44	100	44	7.3
	RI2 (%)	0.77	−33	81	25	50	−8
	RI3 (%)	0.75	−42	88	58	19	−8
TLG	RI2 (%)	0.75	−34	56	67	56	−23
	RI3 (%)	0.79	−53	63	92	38	−37
TLG^PVC	RI2 (%)	0.70	−34	56	50	44	−18
	RI3 (%)	0.78	−54	63	92	31	−38

Figure 2. ROCs examples for prediction of non-responders (n = 16), using (A) SUV_mean with or without PVC, (B) TLG and SUV_mean RI₃, and (C) logistic regression combining baseline MATV and SUV_mean values and their evolution after 8 and 15 days, with and without PVC.