Issues in flow and oxygenation dependent contrast (FLOOD) imaging of tumours Export

@article{citeulike:1908264, abstract = {The sensitivity of blood oxygenation level dependent (BOLD) contrast techniques to changes to tumour deoxyhaemoglobin concentration is of relevance to many strategies in cancer treatments. In the context of tumour studies, which frequently involve the use of agents to modify blood flow, there are underlying physiological changes different to those of BOLD in the brain. Hence we use the term, flow and oxygenation dependent (FLOOD) contrast, to emphasize this difference and the importance of flow effects. We have measured the R2* changes in a prolactinoma tumour model for a variety of vasoactive challenges [carbogen, 100\% oxygen and 100\% nitrogen as different breathing gases, and administration of tumour blood flow modifiers such as calcitonin gene related peptide (CGRP), hydralazine and nicotinamide]. In addition we have measured other relevant physiological parameters, such as bioenergetic status from 31P MRS, and blood pH and glucose, that may change during a vasoactive challenge. Here we discuss how they relate to our understanding of FLOOD contrast in tumours. We frequently observe R2* changes that match the expected action of the vascular stimulus: R2* decreases with agents expected to improve tumour oxygenation and blood flow, and increases with agents designed to increase tumour hypoxia. Unlike most normal tissues, tumours have a chaotic and poorly regulated blood supply, and a mix of glycolytic and oxidative metabolism; thus the response to a vasoactive challenge is not predictable. Changes in blood volume can counteract the effect of blood oxygenation changes, and changes in blood pH and glucose levels can alter oxygen extraction. This can lead to R2* changes that are smaller or the reverse of those expected. To properly interpret FLOOD contrast changes these effects must be accounted for. Copyright {\copyright} 2001 John Wiley \& Sons, Ltd.}, address = {CRC Biomedical Magnetic Resonance Research Group, Department of Biochemistry and Immunology, St George's Hospital Medical School, London SW17 ORE, UK}, author = {Howe, F. A. and Robinson, S. P. and Mcintyre, D. J. O. and Stubbs, M. and Griffiths, J. R.}, citeulike-article-id = {1908264}, citeulike-linkout-0 = {http://dx.doi.org/10.1002/nbm.716}, citeulike-linkout-1 = {http://www3.interscience.wiley.com/cgi-bin/abstract/88014198/ABSTRACT}, doi = {10.1002/nbm.716}, journal = {NMR in Biomedicine}, keywords = {bold, cancer, flood, mri, review}, number = {7-8}, pages = {497--506}, posted-at = {2007-11-13 18:22:09}, priority = {5}, title = {Issues in flow and oxygenation dependent contrast (FLOOD) imaging of tumours}, url = {http://dx.doi.org/10.1002/nbm.716}, volume = {14}, year = {2001} }

TY - JOUR ID - citeulike:1908264 L3 - citeulike-article-id:1908264 N2 - The sensitivity of blood oxygenation level dependent (BOLD) contrast techniques to changes to tumour deoxyhaemoglobin concentration is of relevance to many strategies in cancer treatments. In the context of tumour studies, which frequently involve the use of agents to modify blood flow, there are underlying physiological changes different to those of BOLD in the brain. Hence we use the term, flow and oxygenation dependent (FLOOD) contrast, to emphasize this difference and the importance of flow effects. We have measured the R2* changes in a prolactinoma tumour model for a variety of vasoactive challenges [carbogen, 100% oxygen and 100% nitrogen as different breathing gases, and administration of tumour blood flow modifiers such as calcitonin gene related peptide (CGRP), hydralazine and nicotinamide]. In addition we have measured other relevant physiological parameters, such as bioenergetic status from 31P MRS, and blood pH and glucose, that may change during a vasoactive challenge. Here we discuss how they relate to our understanding of FLOOD contrast in tumours. We frequently observe R2* changes that match the expected action of the vascular stimulus: R2* decreases with agents expected to improve tumour oxygenation and blood flow, and increases with agents designed to increase tumour hypoxia. Unlike most normal tissues, tumours have a chaotic and poorly regulated blood supply, and a mix of glycolytic and oxidative metabolism; thus the response to a vasoactive challenge is not predictable. Changes in blood volume can counteract the effect of blood oxygenation changes, and changes in blood pH and glucose levels can alter oxygen extraction. This can lead to R2* changes that are smaller or the reverse of those expected. To properly interpret FLOOD contrast changes these effects must be accounted for. Copyright © 2001 John Wiley & Sons, Ltd. IS - 7-8 JF - NMR in Biomedicine AD - CRC Biomedical Magnetic Resonance Research Group, Department of Biochemistry and Immunology, St George's Hospital Medical School, London SW17 ORE, UK EP - 506 TI - Issues in flow and oxygenation dependent contrast (FLOOD) imaging of tumours VL - 14 SP - 497 KW - bold KW - cancer KW - flood KW - mri KW - review AU - Howe, FA AU - Robinson, SP AU - Mcintyre, DJO AU - Stubbs, M AU - Griffiths, JR PY - 2001/// UR - http://dx.doi.org/10.1002/nbm.716 ER -