Table 1. Median parameter values for 5-FU metabolism determined by in vivo¹⁹F MRS of tumour-bearing mice.

		Cmaxb		AUCc
		Median (min, max)		Median (min, max)
Metab.	Tumour	5-FU	5-FU+carbogen	5-FU	5-FU+carbogen
5-FU	C26-B	0.98 (0.44, 3.01)	0.78 (0.51, 1.61)	39 (15, 72)	34 (13, 77)
	C26-10	0.78 (0.38, 2.95)	1 (0.45, 2.07)	27 (11, 80)	38 (17, 85)
		P=0.82		P=0.63
Anab.	C26-B	0.35 (0, 0.59)	0.36 (0.21, 0.50)	20 (0, 34)	25 (9, 35)
	C26-10	0.65 (0.31, 2.81)	0.59 (0.45, 2.07)	50 (20, 190)	48 (33, 139)
		P=0.0004		P=0.0001
Catab.	C26-B	0.51 (0, 3.58)	0.36 (0, 0.76)	17 (0, 129)	14 (0, 31)
	C26-10	0.35 (0, 3.56)	0.32 (0, 0.57)	13 (0, 96)	11 (0, 24)
		P=0.23		P=0.36
		5-FU t1/2 (min)d
	C26-B	25.5 (17, 51)	25.5 (8.5, 51)
	C26-10	25.5 (8.5, 42.5)	34 (25.5, 34)
		P=0.51

^aBalb-C mice bearing murine colon carcinoma (s.c.) were examined by ¹⁹F MRS following a bolus injection of 150 mg kg⁻¹ 5-FU (C26-B, n=11; C26-10, n=15) or following 5-FU treatment combined with 9.5 min carbogen breathing (C26-B, n=11; C26-10; n=9). Pharmacokinetic parameters were evaluated for 5-FU, the total NMR-detectable anabolite pool, and the sum of the catabolites FUPA+FBAL. Two-way ANOVA was performed with transformed data (skewed distributions, see Materials and Methods) and gave the P values shown for the main effect of tumour type; for the main effect of carbogen, P>0.05 was found in all cases.

^bC_max=mean of max tissue concentration in arbitrary relative units, determined from ¹⁹F signal integrals normalised to constant tissue volume using the ¹ H signal from tissue water.

^cAUC=area under the concentration–time curve (from 0 to 119 min), normalised to constant tissue volume.

^dt_1/2=half-life of 5-FU (time for decay from C_max to 50% of C_max).