Multislice CEST MRI improves the spatial assessment of tumor pH

Edward A. Randtke, Jeffry C. Granados, Christine M. Howison, Mark D. Pagel, Julio Cárdenas-Rodríguez

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Purpose: Multislice maps of extracellular pH (pHe) are needed to interrogate the heterogeneities of tumors and normal organs. To address this need, we have developed a multislice chemical exchange saturation transfer (CEST) MRI acquisition method with a CEST spectrum-fitting method that measures in vivo pHe over a range of 6.3 to 7.4. Methods: The phase offset multiplanar (POMP) method was adapted for CEST fast imaging with steady-state free precession (FISP) MRI to acquire multiple image slices with a single CEST saturation pulse. The Bloch-McConnell equations were modified to include pH based on a calibration of pH and chemical exchange rate for the contrast agent iopamidol. These equations were used to estimate the pixel-wise pHe values throughout the multislice acidoCEST MR images of the tumor, kidney, bladder, and other tissues of a MDA-MB-231 tumor model. Results: Multislice acidoCEST MRI successfully mapped a gradient of pHe from 6.73 to 6.81 units from the tumor core to rim, and also mapped a gradient of pHe 6.56 to 6.97 across the mouse kidney. The bladder was found to be pHe 6.3. Conclusion: AcidoCEST MRI with POMP acquisition and Bloch-McConnel analysis can map pHe in multiple imaging slices through the tumor, kidney, and bladder. This multislice evaluation facilitates assessments of spatial heterogeneity of tissue pHe. Magn Reson Med 78:97–106, 2017.

Original languageEnglish (US)
Pages (from-to)97-106
Number of pages10
JournalMagnetic Resonance in Medicine
Volume78
Issue number1
DOIs
StatePublished - Jul 2017

Keywords

  • CEST MRI
  • CEST-FISP
  • POMP MRI
  • extracellular pH
  • iopamidol

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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