A novel restrainer device for acquistion of brain images in awake rats.

Functional neuroimaging methods like fMRI and PET are vital in neuroscience research, but require that subjects remain still throughout the scan. In animal research, anesthetic agents are typically applied to facilitate the acquisition of high-quality data with minimal motion artifact. However, anesthesia can have profound effects on brain metabolism, selectively altering dynamic neural networks and confounding the acquired data. To overcome the challenge, we have developed a novel head fixation device designed to support awake rat brain imaging. A validation experiment demonstrated that the device effectively minimizes animal motion throughout the scan, with mean absolute displacement and mean relative displacement of 0.0256 (SD: 0.001) and 0.009 (SD: 0.002), across eight evaluated subjects throughout fMRI image acquisition (total scanning time per subject: 31 min, 12 s). Furthermore, the awake scans did not induce discernable stress to the animals, with stable physiological parameters throughout the scan (Mean HR: 344, Mean RR: 56, Mean SpO2: 94 %) and unaltered serum corticosterone levels (p = 0.159). In conclusion, the device presented in this paper offers an effective and safe method of acquiring functional brain images in rats, allowing researchers to minimize the confounding effects of anesthetic use.

Development and Evaluation of Motion-activated System for Improved Chest Drainage: Bench, In Vivo Results, and Pilot Clinical Use of Technology.

Objective. The aim of this study was to evaluate a motion-activated system (MAS) that applies motion-activated energy (vibration) to prevent chest tube clogging and maintain tube patency. We performed chest tube blood flow analysis in vitro, studied MAS effects on intraluminal clot deposition in vivo, and conducted a pilot clinical test. Background. Chest tube clogging is known to adversely contribute to postoperative cardiac surgery outcomes. Methods. The MAS was tested in vitro with a blood-filled chest tube model for device acceleration and performance. In vivo acute hemothorax studies (n = 5) were performed in healthy pigs (48.0 ± 2 kg) to evaluate the drainage in MAS versus control (no device) groups. Using a high-speed camera (FASTCAM Mini AX200, 100 mm Zeiss lens) in an additional animal study (n = 1), intraluminal whole-blood activation imaging of the chest tube (32 Fr) was made. The pilot clinical study (n = 12) consisted of up to a 30 minutes device tolerance test. Results. In vitro MAS testing suggested optimal device performance. The 2-hour in vivo evaluation showed a longer incremental drainage in the MAS group versus control. The total drainage in the MAS group was significantly higher than that in the control group (379 ± 144 mL vs 143 ± 40 mL; P = .0097), indicating tube patency. The high-speed camera images showed a characteristic intraluminal blood "swirling" pattern. Clinical data showed no discomfort with the MAS use (pleural = 4; mediastinal = 8). Conclusions. The MAS showed optimal performance at bench and better drainage profile in vivo. The clinical trial showed patients' tolerance to the MAS and device safety.

Anti-clogging mechanisms of a motion-activated chest tube patency maintenance system: Histology and high-speed camera assessment.

The motion-activated system (MAS) employs vibration to prevent intraluminal chest tube clogging. We evaluated the intraluminal clot formation inside chest tubes using high-speed camera imaging and postexplant histology analysis of thrombus. The chest tube clogging was tested (MAS vs. control) in acute hemothorax porcine models (n = 5). The whole tubes with blood clots were fixed with formalin-acetic acid solution and cut into cross-sections, proceeded for H&E-stained paraffin-embedded tissue sections (MAS sections, n = 11; control sections, n = 11), and analyzed. As a separate effort, a high-speed camera (FASTCAM Mini AX200, 100-mm Zeiss lens) was used to visualize the whole blood clogging pattern inside the chest tube cross-sectional view. Histology revealed a thin string-like fibrin deposition, which showed spiral eddy or aggregate within the blood clots in most sections of Group MAS, but not in those of the control group. Histology findings were compatible with high-speed camera views. The high-speed camera images showed a device-specific intraluminal blood "swirling" pattern. Our findings suggest that a continuous spiral flow in blood within the chest tube (MAS vs. static control) contributes to the formation of a spiral string-like fibrin network during consumption of coagulation factors. As a result, the spiral flow may prevent formation of thick band-like fibrin deposits sticking to the inner tube surface and causing tube clogging, and thus may positively affect chest tube patency and drainage.

Instrumentation of off-the-shelf ultrasound system for measurement of probe forces during freehand imaging.

Ultrasound is a popular and affordable imaging modality, but the nature of freehand ultrasound operation leads to unknown applied loads at non-quantifiable angles. The purpose of this paper was to demonstrate an instrumentation strategy for an ultrasound system to measure probe forces and orientation during freehand imaging to characterize the interaction between the probe and soft-tissue as well as enhance repeatability. The instrumentation included a 6-axis load cell, an inertial measurement unit, and an optional sensor for camera-based motion capture. A known method for compensation of the ultrasound probe weight was implemented, and a novel method for temporal synchronization was developed. While load and optical sensing was previously achieved, this paper presents a strategy for potential instrumentation on a variety of ultrasound machines. A key feature was the temporal synchronization, utilizing the electrocardiogram (EKG) feature built-in to the ultrasound. The system was used to perform anatomical imaging of tissue layers of musculoskeletal extremities and imaging during indentation on an in vivo subject and an in vitro specimen. The outcomes of the instrumentation strategy were demonstrated during minimal force and indentation imaging. In short, the system presented robust instrumentation of an existing ultrasound system to fully characterize the probe force, orientation, and optionally its movement during imaging while efficiently synchronizing all data. Researchers may use the instrumentation strategy on any EKG capable ultrasound systems if mechanical characterization of soft tissue or minimization of forces and deformations of tissue during anatomical imaging are desired.