Abstract 17749: Magnetohydrodynamic Quantification of the Peripheral Perfusion Index in High-field MRI
Background: Peripheral Perfusion Index (PFI) measurements are typically used in the assessment of total body perfusion, commonly serving as indicators of tissue hypoxia and other potential risks . PFI is typically recorded with pulse oximetry (PO), an indirect measurement. Magnetohydrodynamic Voltages (VMHD), caused by interaction of the MRI’s high-magnetic-field with blood-flow , are observed on ECG recordings performed inside MRI.
Objectives: Develop a method to directly assess patient perfusion levels and PFI using VMHD observed on 12-lead ECGs in MRI.
Methods: ECG data was collected in 5 healthy volunteers, using an MRI-conditional 12-lead ECG system. Measurements were performed while incrementally moving the bed into the bore of a 3T MRI. ECG sets were recorded at each positional step, and the real-ECG-signal subtracted from the total trace observed, thus extracting the VMHD contribution in each trace. A Vectorcardiogram (VCG) was then synthesized from the individual MHD signals using an inverse Dower transform , and integrated over the cardiac S-T segment, generating a metric proportional to the summed segmental perfusion (SSP) contributions. The SP at each step was solved for by using a linear decomposition matrix, weighting each term based on the magnetic field exposure. VMHD based PFI estimates were calculated as the ratio of aortic to extremity SP , and compared to PO- based measurements.
Results: VMHD based PFI was calculated for all subjects, providing an error of <8% for each subject relative to PO-based measurements.
Conclusions: VMHD-based PFI and perfusion measurements provide characteristic SP patterns and perfusion levels, at comparable accuracy to standard clinical methods.
Ref:  Lima, Circulation, 2002.  Gupta, IEEE, 2008.  Dower, Clinical Cardiology, 1980.  Ridling, PediatrNurs, 2009.
Acknowledgements: NIH U41-RR019703, NIH R03 EB013873-01A1, SBIR-1 R43 HL110427-01
- Perfusion imaging
- Peripheral vasculature
- Magnetic resonance
- Magnetic resonance imaging
Author Disclosures: T. Gregory: None. E.J. Schmidt: None. S.H. Zhang: None. J.R. Murrow: None. Z.T. Tse: None.
- © 2014 by American Heart Association, Inc.