Abstract: FR-PO989

Portable Magnetic Resonance Sensor to Detect Volume Changes

Session Information

Category: Bioengineering and Informatics

  • 101 Bioengineering and Informatics

Authors

  • Colucci, Lina Avancini, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
  • Corapi, Kristin M., Massachusetts General Hospital, Boston, Massachusetts, United States
  • Parada, Xavier F., Massachusetts General Hospital, Boston, Massachusetts, United States
  • Lin, Herbert Y., Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts, United States
  • Cima, Michael J., MIT, Cambridge, Massachusetts, United States
Background

Magnetic resonance technology provides information about the quantity, volume, and motion of water. In this study, we used portable, non-invasive MR sensors to monitor water movement in healthy controls and hemodialysis (HD) patients.

Methods

Adult, male HD patients and controls were enrolled. A custom, single-sided MR sensor developed by the Cima Lab at MIT was used to collect data from the upper calf of HD patients before and after dialysis. Controls had data collected before and after 4 hours of bedrest. The MR sensor collected T2 relaxation time measurements of a cubic centimeter voxel that included subcutaneous tissue and muscle. The T2 relaxation time measurements were analyzed with an inverse Laplace transformation to generate a relaxogram. The individual relaxograms were averaged together in each group.

Results

Demographics are shown in table 1. Free fluids are associated with long T2 relaxation times whereas bound hydrogen in connective tissues are associated with short T2 relaxation times. We observe that controls have nearly identical relaxograms at 0 and 4 hrs. Dialysis patients before treatment display an added peak in their relaxogram at higher relaxation times, representing excess free fluid. We demonstrate that this peak shifts to the left after dialysis and that the relaxogram of the HD patients becomes comparable to controls (Figure 1a-d).

Conclusion

Portable MR sensors may quantify fluid overload in HD patients non-invasively. Further study is necessary to understand the sensitivity of these sensors to fluid shifts during HD and develop an absolute scale that relates relaxation time measurements to fluid overload.

Demographics of Participants
 HD patients (n=4)Healthy Controls (n=5)
Age (yrs)56.8 (9.9)55.2 (5.9)
Weight (kg)84.7 (21.1)76.4 (14.5)
BMI (kg/m2)29.1 (7.0)25.9 (5.3)
Fluid removal (mL)2725 (1041)NA

data presented as mean (SD)

Funding

  • Private Foundation Support