Fluorine-19 [19F] MRI oximetry and 1H blood oxygen level-dependent (BOLD) MRI were used to investigate tumor oxygenation in rat breast 13762NF carcinomas, and correlations between the techniques were examined. A range of tissue oxygen partial pressure (pO2) values was found in the nine tumors while the anesthetized rats breathed air, with individual tumor pO2 ranging from a mean of 1 to 36 torr and hypoxic fraction (HF10) (<10 torr) ranging from 0% to 75%, indicating a large intra- and intertumor heterogeneity. Breathing oxygen produced significant increase in tumor pO2 (mean ΔpO2 = 50 torr) and decrease in HF10 (P < 0.01). 1H BOLD MRI observed using a spin echoplanar imaging (EPI) sequence revealed a heterogeneous response and significant increase in mean tumor signal intensity (SI) (ΔSI = 7%, P < 0.01). R2* measured by multigradient-echo (MGRE) MRI decreased significantly in response to oxygen (mean ΔR2* = -4 s-1; P < 0.05). A significant correlation was found between changes in mean tumor pO2 and mean EPI BOLD ΔSI accompanying oxygen breathing (r2 > 0.7, P < 0.001). Our results suggest that BOLD MRI provides information about tumor oxygenation and may be useful to predict pO2 changes accompanying interventions. Significantly, the magnitude of the BOLD response appears to be predictive for residual tumor HFs.
- F MRI
- Transverse relaxation rate R *
- Tumor oxygenation
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging