Handheld Laser Speckle Imaging System for Neonatal Blood Flow Imaging
- Author(s): Farraro, Ryan T.
- Advisor(s): Choi, Bernard H.
- et al.
Background and Objectives:
Although abnormal blood flow is linked to clinical risk of illness in neonates, clinicians typically do not integrate flow measurements into routine monitoring in the neonatal intensive care unit (NICU). We and other research groups have previously demonstrated the ability of Laser Speckle Imaging (LSI) to measure changes in blood flow in both a laboratory and clinical settings. We postulate that LSI, in a clinic-friendly form factor, can provide important hemodynamic information in the NICU. Here, I describe initial efforts to develop a handheld LSI system and deploy it to University of California, Irvine Medical Center NICU.
I designed and fabricated a handheld LSI system based on design principles to insure successful implementation into a clinical setting. Using in-vitro tissue phantom systems, I assessed the system performance of handheld LSI versus a traditional mounted configuration. I collected multi-user data (n=7) to assess the variation in flow measurements attributed to user performance. I collected data from two in-vivo occlusion models to demonstrate that the handheld device can detect both qualitative and quantitative changes in blood flow. Finally, I acquired data from an on-going NICU based clinical study (n=30, to date) in which we collected LSI images of abdomen and the heel over a period of several months.
I demonstrate that the handheld nature of the device has little effect on the flow measurement sensitivity via a study that was focused on the characterization of tissue simulating phantoms. Flow phantoms were characterized using both bench top and handheld LSI instruments. I show that measurements of flow from these phantoms is not user dependent based on testing using a pool of 7 minimally trained users. I demonstrate that the handheld LSI system measures trends in flow that are similar to those reported previously using bench top LSI systems during in-vivo occlusion models. I observed up to an 83.9% increase in flow index measured in neonates at the abdomen after feeding, while only up to a 16.1% increase was observed in the heel. Lastly, I observed a statistically significant difference between the maximum range of flow index values measured at the abdomen in necrotizing enterocolitis neonates and a healthy population (P=.015).
The handheld LSI system can measure changes in blood flow and is minimally sensitive to errors due to handheld motion. Flow changes found in the abdomen warrant further studies to investigate the feasibility of using the LSI to detect compromised intestinal blood flow in neonates. These results suggest that LSI may be capable of providing additional screening for neonates with suspected gut pathology.