High resolution pHe imaging of rat glioma using pH-dependent relaxivity
Previous studies using MR spectroscopy have shown that the extracellular pH (pHe) of tumors is acidic compared to normal tissues. This has a number of important sequelae that favor the emergence of more aggressive and therapy‐resistant tumors. New MRI methods based on pH‐sensitive T1 relaxivity are...
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Published in | Magnetic resonance in medicine Vol. 55; no. 2; pp. 309 - 315 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Hoboken
Wiley Subscription Services, Inc., A Wiley Company
01.02.2006
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Subjects | |
Online Access | Get full text |
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Summary: | Previous studies using MR spectroscopy have shown that the extracellular pH (pHe) of tumors is acidic compared to normal tissues. This has a number of important sequelae that favor the emergence of more aggressive and therapy‐resistant tumors. New MRI methods based on pH‐sensitive T1 relaxivity are an attractive alternative to previous spectroscopic methods, as they allow improvements in spatial and temporal resolution. Recently, pH‐dependent GdDOTA‐4AmP5‐ and a pH‐independent analog, GdDOTP5‐, were used to image renal pH in mice. The current study has used a similar approach to image pHe in rat gliomas. Significant differences were observed compared to the renal study. First, the relaxivity of GdDOTP5‐ was found to be affected by the higher extracellular protein content of tumors. Second, the pixel‐by‐pixel analysis of the GdDOTP5‐ and GdDOTA‐4AmP5‐ pharmacokinetics showed significant dispersion, likely due to the temporal fluctuations in tumor perfusion. However, there was a robust correlation between the maximal enhancements produced by the two boluses. Therefore, to account for the local time‐courses differences, pHe maps were calculated at the time of maximal enhancement in each pixel. Finally, the comparison of the pHe and the time to maximal intensity maps revealed an inverse relationship between pHe and tumor perfusion. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc. |
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Bibliography: | istex:DF438BAED1D2DA1E3543068418C5AF90B6A4C7B4 NCI - No. R01 Ca 077575; No. R24 088578 Division of Research Resources and the National Institutes of Health - No. RR-02584 National Institutes of Health - No. CA-84697 Robert A. Welch Foundation - No. AT-584 ark:/67375/WNG-55B7HJ37-C ArticleID:MRM20773 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0740-3194 1522-2594 |
DOI: | 10.1002/mrm.20773 |