Towards artifact-free non-invasive renal and hepatic functional MRI: development of an organ-specific navigator-based pCASL sequence with EPI acquisition

• Applicant: Dr. Ke Zhang
• Subject Area: Radiology ; Medical Physics, Biomedical Technology
• Term: from 2022 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 507778602

• Final Report Year: 2025

Final Report Abstract

Subtle local changes in renal and hepatic perfusion are important indicators of developing disease; if quantified, they can be used to grade malignancy in neoplastic processes, and to monitor organ function during disease treatment. While glomerular filtration rate is considered the gold standard of kidney function evaluation, it has no spatial correlate, which is why cross-sectional perfusion measurements are more accurate and specific. Considering that the administration of nephrotoxic contrast agent is ill advised in patients with severe kidney function impairment and patients with allergies to contrast agents, non-invasive MRI perfusion measurements with arterial spin labelling (ASL) techniques are gaining in importance. They provide quantitative measurements of organ perfusion by using magnetically labeled blood as an endogenous tracer. In neuroimaging, pseudocontinuous ASL (pCASL) has been developed recently and shown to provide a relatively reliable assessment of cerebral perfusion. In the abdominal imaging setting, however, motion artifacts significantly complicate the application of the pCASL technique. To address this problem, we have developed an organ-specific navigator-based slice tracking technique using an Echo-Planar Imaging (EPI) based sequence in renal and hepatic perfusion measurements to prospectively compensate for respiratory motion artifacts. This will allow an artifact-free free-breathing multi-slice and non-invasive renal and hepatic perfusion imaging. To enhance the signal-noise-ratio (SNR) velocity selective ASL (VSASL) has been implemented and simulated for liver ASL. VSASL tags blood according to its speed and produces a magnetic bolus right near the microvasculature in the imaging area: In contrast to spatially selective pulsed and pCASL approaches, VSASL is insensitive to transit delay effects and no labeling plan was used. The sequences have been developed for a 1.5 Tesla MRI scanner (Siemens Aera), validated in volunteers, and compared against standard ASL MRI techniques.

Publications

• Navigator-triggered kidney vessel architecture imaging. ISMRM; 2021
  Zhang K., Triphan S., Kurz F. et al.
  
• Navigator-based slice tracking for kidney pCASL using EPI acquisition. ISMRM Annual Meeting. ISMRM.
  Zhang, Ke; Triphan, Simon; Kurz, Felix; Ziener, Chrstian; Kauczor, Hans-Ulrich; Schlemmer, Heinz-Peter & Sedlaczek, Oliver
  
• Comparison of velocity-selective-inversion arterial spin labeling schemes. ISMRM Annual Meeting. ISMRM.
  Zhang, Ke; Triphan, Simon; Sedlaczek, Oliver; Ziener, Christian; Kauczor, Hans-Ulrich; Schlemmer, Heinz-Peter & Kurz, Felix
  
• Navigator-based slice tracking for liver pCASL using spin-echo EPI acquisition. ISMRM Annual Meeting. ISMRM.
  Zhang, Ke; Triphan, Simon; Sedlaczek, Oliver; Ziener, Christian; Kauczor, Hans-Ulrich; Schlemmer, Heinz-Peter & Kurz, Felix
  
• Navigator‐based slice tracking for kidney pCASL using spin‐echo EPI acquisition. Magnetic Resonance in Medicine, 90(1), 231-239.
  Zhang, Ke; Triphan, Simon M. F.; Ziener, Christian H.; Jende, Johann M. E.; Kauczor, Hans‐Ulrich; Schlemmer, Heinz‐Peter; Sedlaczek, Oliver & Kurz, Felix T.
  
• Navigator‐based motion compensation for liver BOLD measurement with five‐echo SAGE EPI and breath‐hold task. NMR in Biomedicine, 37(10).
  Zhang, Ke; Triphan, Simon M. F.; Wielpütz, Mark O.; Ziener, Christian H.; Ladd, Mark E.; Schlemmer, Heinz‐Peter; Kauczor, Hans‐Ulrich; Sedlaczek, Oliver & Kurz, Felix T.
  
• Simultaneous T1, T2 and T2⁎ mapping of the liver with multi-shot MI-SAGE. Magnetic Resonance Imaging, 105, 75-81.
  Zhang, Ke; Triphan, Simon M.F.; Wielpütz, Mark O.; Ziener, Christian H.; Ladd, Mark E.; Schlemmer, Heinz-Peter; Kauczor, Hans-Ulrich; Kurz, Felix T. & Sedlaczek, Oliver
  
• Non-contrast free-breathing liver perfusion imaging using velocity selective ASL combined with prospective motion compensation. Zeitschrift für Medizinische Physik, 35(1), 87-97.
  Zhang, Ke; Triphan, Simon M.F.; Wielpütz, Mark O.; Ziener, Christian H.; Ladd, Mark E.; Schlemmer, Heinz-Peter; Kauczor, Hans-Ulrich; Sedlaczek, Oliver & Kurz, Felix T.