Tumour T1 changes in vivo are highly predictive of response to chemotherapy and reflect the number of viable tumour cells – a preclinical MR study in mice

Table 1 Summary of RIF-1 measurements in vivo and ex vivo

Parameter	Vehicle		Everolimus		T/C
Parameter	Day 0	Day 5	Day 0	Day 5	T/C
TVol (mm³)	447 ± 75	1118 ± 150	706 ± 85	736 ± 100	0.05***
T₁ (msec)	2266 ± 46	2265 ± 30	2335 ± 23	2090 ± 45	0.89**
choline/H₂O [a.u.]	2.72 ± 0.18	2.72 ± 0.2	2.6 ± 0.12	1.82 ± 0.32	0.73
CH₂/H₂O [a.u.]	6.44 ± 0.85	7.3 ± 1.17	6.89 ± 0.35	11.0 ± 1.5	1.3
CH₃/H₂O [a.u.]	2.56 ± 0.43	2.86 ± 1.74	3.06 ± 0.34	4.87 ± 0.72	1.2
PUFA/H₂O [a.u.]	0.1 ± 0.1	0.37 ± 0.24	0.25 ± 0.25	0.8 ± 0.39	2.2
creatine/H₂O [a.u.]	1.27 ± 0.15	1.14 ± 0.05	1.07 ± 0.06	0.89 ± 0.09	0.9
total area (mm²)	-	65.8 ± 10.0	-	43.6 ± 5.6	0.66
viable area (mm²)	-	52.1 ± 9.4	-	33.1 ± 4.7	0.64
%necrosis	-	21.5 ± 6.1	-	24.9 ± 3.3	1.16
total cells (thousand)	-	489 ± 82	-	328 ± 48	0.67
cells/viable mm²	-	9671 ± 454	-	9923 ± 562	1.03
%Csp⁺ area	-	0.39 ± 0.07	-	0.27 ± 0.02	0.7
BV per mm²	-	728 ± 159	-	768 ± 37	1.06
%Ki67⁺ cells	-	44.6 ± 2.5	-	26.5 ± 1.0	0.59***
Ki67⁺cells/mm²	-	4274 ± 205	-	2614 ± 141	0.61***
Ki67^- cells/mm²	-	5396 ± 457	-	7309 ± 462	1.35*

C3H mice bearing RIF-1 tumours were treated with everolimus (10 mg/kg/day, n = 7) or vehicle (n = 7) for 5 days prior to sacrifice. Tumour volume, T₁ and the various MRS parameters were quantified prior to treatment (day 0) and after 5 days treatment. Animals were then culled and the tumours ablated and prepared for immunohistochemistry as described in Methods. After immunostaining for Ki67 and cleaved caspase-3, the entire tumour sections were scanned to provide viable and necrotic areas in mm². The number of cells and the number and percentage staining for Ki67 and caspase-3 is shown only for the viable area but essentially identical results were obtained if the entire area was used. Blood vessels (BV) were quantified from CD31 stained slices. All results show the mean ± SEM for each tumour, significant changes are indicated by emboldened numbers where *p < 0.05, **p < 0.01, ***p < 0.001 comparing the two treatment group means (2-tailed t-test).

ISSN: 1471-2407