title: Correlation of radiobiological assays of hypoxic fraction with phosphorus-31 magnetic resonance spectroscopy across multiple tumor lines.
abstract: Hypoxic fractions were measured in multiple tumor models and compared to 31P magnetic resonance spectroscopy (MRS) parameters. Hypoxic fractions were measured by excision assays in intramuscular and subcutaneous RIF-1 tumors, large and small SCCVII tumors, and KHT tumors. The hypoxic fractions ranged from 3% (small SCCVII) to 21% (KHT). Measurements of 31P MRS parameters (indices of tumor metabolism) were made under the same conditions used in the hypoxic fraction assays. The PCR/Pi ratios in the five tumor models were strongly correlated (r2 = 0.98, tau = 1.00, P < 0.02) with their hypoxic fractions, and the NTP/Pi ratio was weakly correlated (r2 = 0.67, tau = 0.60, P < 0.17) with hypoxic fraction. Smaller values of the PCr/Pi and NTP/Pi ratios were found in the tumors with larger hypoxic fractions. These experiments indicate that 31P MRS may provide a relative measurement of hypoxic fractions across different tumor lines that can be applied non-invasively to individual tumors.
authors.affiliation: Biophysics Research Institute, Medical College of Wisconsin, Milwaukee 53226, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Li
authors.forename: G Y
authors.initials: GY
authors.lastname: Jin
authors.forename: B L
authors.initials: BL
authors.lastname: Fish
authors.forename: J E
authors.initials: JE
authors.lastname: Moulder
mesh_terms: D000818:Animals; D015687:Cell Hypoxia; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008809:Mice, Inbred C3H; D009374:Neoplasms, Experimental / Q000473:pathology* / Q000532:radiotherapy*; D010100:Oxygen / Q000378:metabolism; D010759:Phosphorus Isotopes; D011048:Polarography; D011853:Radiobiology; D014407:Tumor Cells, Cultured
chemical_list: D010759:Phosphorus Isotopes; D010100:Oxygen