The effect of flow on blood oxygen level dependent (R * 2 ) MRI of orthotopic lung tumors

Magn Reson Med. 2019 Jun;81(6):3787-3797. doi: 10.1002/mrm.27661. Epub 2019 Jan 30.

Abstract

Purpose: Blood oxygen level dependent (BOLD) MRI based on R 2 * measurements can provide insights into tumor vascular oxygenation. However, measurements are susceptible to blood flow, which may vary accompanying a hyperoxic gas challenge. We investigated flow sensitivity by comparing R 2 * measurements with and without flow suppression (fs) in 2 orthotopic lung xenograft tumor models.

Methods: H460 (n = 20) and A549 (n = 20) human lung tumor xenografts were induced by surgical implantation of cancer cells in the right lung of nude rats. MRI was performed at 4.7T after tumors reached 5 to 8 mm in diameter. A multiecho gradient echo MRI sequence was acquired with and without spatial saturation bands on each side of the imaging plane to evaluate the effect of flow on R 2 * . fs and non-fs R 2 * MRI measurements were interleaved during an oxygen breathing challenge (from air to 100% O2 ). T 2 * -weighted signal intensity changes (ΔSI(%)) and R 2 * measurements were obtained for regions of interest and on a voxel-by-voxel basis and discrepancies quantified with Bland-Altman analysis.

Results: Flow suppression affected ΔSI(%) and R 2 * measurements in each tumor model. Average discrepancy and limits of agreement from Bland-Altman analyses revealed greater flow-related bias in A549 than H460.

Conclusion: The effect of flow on R 2 * , and hence BOLD, was tumor model dependent with measurements being more sensitive in well-perfused A549 tumors.

Keywords: blood oxygen level dependent (BOLD); flow-suppression; hypoxia; lung cancer; oxygen-sensitive MRI.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • A549 Cells
  • Animals
  • Female
  • Heterografts
  • Humans
  • Lung Neoplasms* / diagnostic imaging
  • Lung Neoplasms* / metabolism
  • Lung Neoplasms* / pathology
  • Lung* / diagnostic imaging
  • Lung* / metabolism
  • Magnetic Resonance Imaging*
  • Oximetry / methods
  • Oxygen* / blood
  • Oxygen* / metabolism
  • Rats
  • Rats, Nude

Substances

  • Oxygen