Effect of carbogen on tumor oxygenation: combined fluorine-19 and proton MRI measurements Export

@article{FA02, abstract = { : Blood oxygen level dependent (BOLD) contrast in magnetic resonance imaging (MRI) has been widely used for noninvasive evaluation of the effects of tumor-oxygenating agents. However, there have been few tests of the validity of this method. The goal of the present work was to use the T 1 of fluorine-19 in perfluorocarbon (PFC) emulsions as a ” gold standard” for comparison with BOLD MRI. : Rats bearing R3230AC tumors implanted in the hind limb were injected with an emulsion of perfluoro-15-crown-5-ether for 2–3 days before experiments, which ensured that the PFC emulsion concentrated in the tumors. We correlated changes in tumor oxygenation caused by carbogen inhalation measured by 1 H BOLD MRI with quantitative 19 F measurements. The 19 F spin-lattice relaxation rate R 1 (= 1/T 1 ) was measured to determine initial oxygen tension (pO 2 ) in each image pixel containing the PFC, and changes in pO 2 during carbogen (95\% O 2 , 5\% CO 2 ) breathing. In a second carbogen breathing period, changes in water signal linewidth were measured using high spectral and spatial resolution imaging. 19 F and 1 H measurements were used to classify pixels as responders to carbogen (pixels where oxygen increased significantly) or nonresponders (no significant change in tumor oxygenation). : The 19 F and 1 H measurements agreed in 65\% ± 11\% of pixels ( n = 14). Agreement was even stronger among pixels where 1 H showed increased oxygenation; 19 F measurements agreed with 1 H measurements in over 79\% ± 11\% of these pixels. Similarly, there was strong agreement between the two modalities in pixels where 19 F reported no change in pO 2 ; 1 H also showed no changes in 76\% ± 18\% of these pixels. Quantitative correlation of changes T 2 * (ΔT 2 *) in 1 H and changes R 1 (ΔR 1 ) in 19 F was weak during carbogen breathing, and averaged over the whole tumor was 0.40 for 14 experiments. However, the spatial patterns of 1 H and 19 F changes were qualitatively very similar. In hypoxic regions that were identified based on long 19 F T 1 (>2.53 s), 19 F and 1 H MRI agreed that carbogen had relatively weak effects. : These results suggest that 1 H BOLD MRI reliably identifies increases in tumor pO 2 . In hypoxic regions where increases in pO 2 are most desirable, carbogen was ineffective. The data suggest that 19 F and 1 H MRI can be used individually or in combination to guide the design of improved tumor-oxygenating agents.}, author = {Fan, X.}, citeulike-article-id = {4216979}, citeulike-linkout-0 = {http://dx.doi.org/10.1016/S0360-3016(02)03035-3}, citeulike-linkout-1 = {http://linkinghub.elsevier.com/retrieve/pii/S0360-3016(02)03035-3}, day = {15}, doi = {10.1016/S0360-3016(02)03035-3}, issn = {03603016}, journal = {International Journal of Radiation Oncology*Biology*Physics}, keywords = {19f-mri, 19fo, bold, fa02, perfluorocarbons}, month = {November}, number = {4}, pages = {1202--1209}, posted-at = {2009-03-25 09:39:48}, priority = {0}, title = {Effect of carbogen on tumor oxygenation: combined fluorine-19 and proton MRI measurements}, url = {http://dx.doi.org/10.1016/S0360-3016(02)03035-3}, volume = {54}, year = {2002} }

TY - JOUR ID - FA02 L3 - citeulike-article-id:4216979 N2 - : Blood oxygen level dependent (BOLD) contrast in magnetic resonance imaging (MRI) has been widely used for noninvasive evaluation of the effects of tumor-oxygenating agents. However, there have been few tests of the validity of this method. The goal of the present work was to use the T 1 of fluorine-19 in perfluorocarbon (PFC) emulsions as a “gold standard” for comparison with BOLD MRI. : Rats bearing R3230AC tumors implanted in the hind limb were injected with an emulsion of perfluoro-15-crown-5-ether for 2–3 days before experiments, which ensured that the PFC emulsion concentrated in the tumors. We correlated changes in tumor oxygenation caused by carbogen inhalation measured by 1 H BOLD MRI with quantitative 19 F measurements. The 19 F spin-lattice relaxation rate R 1 (= 1/T 1 ) was measured to determine initial oxygen tension (pO 2 ) in each image pixel containing the PFC, and changes in pO 2 during carbogen (95% O 2 , 5% CO 2 ) breathing. In a second carbogen breathing period, changes in water signal linewidth were measured using high spectral and spatial resolution imaging. 19 F and 1 H measurements were used to classify pixels as responders to carbogen (pixels where oxygen increased significantly) or nonresponders (no significant change in tumor oxygenation). : The 19 F and 1 H measurements agreed in 65% ± 11% of pixels ( n = 14). Agreement was even stronger among pixels where 1 H showed increased oxygenation; 19 F measurements agreed with 1 H measurements in over 79% ± 11% of these pixels. Similarly, there was strong agreement between the two modalities in pixels where 19 F reported no change in pO 2 ; 1 H also showed no changes in 76% ± 18% of these pixels. Quantitative correlation of changes T 2 * (ΔT 2 *) in 1 H and changes R 1 (ΔR 1 ) in 19 F was weak during carbogen breathing, and averaged over the whole tumor was 0.40 for 14 experiments. However, the spatial patterns of 1 H and 19 F changes were qualitatively very similar. In hypoxic regions that were identified based on long 19 F T 1 (>2.53 s), 19 F and 1 H MRI agreed that carbogen had relatively weak effects. : These results suggest that 1 H BOLD MRI reliably identifies increases in tumor pO 2 . In hypoxic regions where increases in pO 2 are most desirable, carbogen was ineffective. The data suggest that 19 F and 1 H MRI can be used individually or in combination to guide the design of improved tumor-oxygenating agents. IS - 4 JF - International Journal of Radiation Oncology*Biology*Physics SN - 03603016 EP - 1209 TI - Effect of carbogen on tumor oxygenation: combined fluorine-19 and proton MRI measurements VL - 54 SP - 1202 KW - 19f-mri KW - 19fo KW - bold KW - fa02 KW - perfluorocarbons AU - Fan, X PY - 2002/11/15/ UR - http://dx.doi.org/10.1016/S0360-3016(02)03035-3 ER -