Abstract: SA-PO424
Rapid Fluid Assessment in Patients on Hemodialysis Using Portable Single-Sided Magnetic Resonance Sensor
Session Information
- Hemodialysis and Frequent Dialysis - 2
October 26, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Dialysis
- 801 Dialysis: Hemodialysis and Frequent Dialysis
Authors
- Heo, Won-Seok, Massachusetts Institute of Technology Koch Institute for Integrative Cancer Research, Cambridge, Massachusetts, United States
- Sherman, Sydney, Massachusetts Institute of Technology Koch Institute for Integrative Cancer Research, Cambridge, Massachusetts, United States
- Zammit, Alexa S., Massachusetts Institute of Technology Koch Institute for Integrative Cancer Research, Cambridge, Massachusetts, United States
- Bouchouari, Houda, Massachusetts General Hospital Nephrology Division, Boston, Massachusetts, United States
- Higginbotham, Haley, Massachusetts Institute of Technology Koch Institute for Integrative Cancer Research, Cambridge, Massachusetts, United States
- Nicholls, Oliver, Massachusetts Institute of Technology Koch Institute for Integrative Cancer Research, Cambridge, Massachusetts, United States
- Kalim, Sahir, Massachusetts General Hospital Nephrology Division, Boston, Massachusetts, United States
- Nigwekar, Sagar U., Massachusetts General Hospital Nephrology Division, Boston, Massachusetts, United States
- Cima, Michael J., Massachusetts Institute of Technology Koch Institute for Integrative Cancer Research, Cambridge, Massachusetts, United States
Background
Fluid overload poses health risks caused by hypertension among hemodialysis (HD) patients. Current fluid assessment methods, such as urine or blood screening and bioimpedance, are not sensitive to early-stage changes in volume. This study presents a noninvasive, rapid, and cost-effective method for assessing fluid status using a portable single-sided nuclear magnetic resonance (NMR) sensor, enabling multicomponent T2 relaxometry analysis of intra- and extra-cellular fluid in skeletal muscle tissues.
Methods
The NMR sensor (22×18×11 cm) consists of 0.5 in cube N52 Nd magnets, creating a homogeneous 0.2 T magnetic field 8 mm above the surface at 8.4 MHz. A CPMG pulse train is transmitted via a single surface transceiver coil, seated on a 0.5 mm AlN layer for heat dissipation. The clinical study measured T2 from end-stage renal disease (ESRD) patients’ calves undergoing HD, excluding those with obvious signs of edema, compared to healthy controls (HC). T2 relaxation was modeled as tri-exponential decay using a nonlinear least squares optimization method to obtain relative amplitude 2 (RA2).
Results
We observed a decrease in RA2 from pre- to post-HD in every individual case. Population average RA2 values were approximately 41.5% and 31.5% for pre- and post-HD at MGH (p = 0.021), 43% and 38% for pre- and post-HD at Fresenius Kidney Care (FKC), and 30% for HC at MIT, showing lower RA2 compared to both pre-HD measurements at MGH (p = 0.014) and FKC (p = 0.022) (Fig. 1). Additional consented HD outpatients and HC volunteers will be measured in the coming months to support our findings.
Conclusion
This work demonstrates quantitative point-of-care volume status evaluation using an NMR sensor in vivo, providing noninvasive, real-time monitoring of fluid loss during dialysis by performing multicomponent T2 relaxometry localized to skeletal muscle, reducing system complexity and cost compared to MRI. These findings suggest that bedside NMR can effectively identify fluid overload or dehydration in ESRD patients and other hypervolemic conditions.
RA2 for 8 and 6 HD at MGH and FKC, respectively, and 7 HC at MIT.
Funding
- Other NIH Support