Gating signals for scanning synchronization from local body movements, respiration activity or heartbeat

The physiological monitoring subsystem contains several sensors on the animal bed, with electronics and a software package for imaging, real-time analysis and scan gating. A miniature color TV-camera is mounted on the animal bed and equipped with white LED illumination to produce a real-time image of the animal during the scan. The software analyzes the video stream from a user-selected area of the image, which the operator can position on a part of the animal body where breathing movement is visible. These movements are detected and converted into a movement waveform to provide a monitor of breathing and a gating signal for synchronized scanning.

The physiological monitoring subsystem includes an air / gas movement sensor for direct breathing detection. This signal can be selected for gated acquisition with adjustable delay between the breathing signal and camera acquisition. For optimal control and precision of breathing-gated scanning, a small animal ventilator can be connected which forces the animal's breathing via tracheal intubation, and delivers electronic pulse for gating.

The physiological monitoring system contains a temperature sensor on the animal bed, which can be placed near the animal. Airflow from a fan is heated to attain a user-specified temperature, warming the animal. Current temperature and target temperature are displayed in the physiological monitoring software window.

The ECG monitoring system consists of a sensitive amplifier and specially developed ECG electrodes and wiring, which contain no metal parts to avoid artifacts in the reconstructed slices.The electrodes use advanced carbon-fiber conductive parts with x-ray absorption similar to the animal body. The ECG signal can be used for scan gating (giving a drug to slow down heart rate) and can be seen on screen in real time. Special program can acquire analogue signal through sound card of the computer and show ECG curve in real time on the screen (top picture).

Picture in the bottom shows shadow projections (top) and reconstructed slices (bottom) through a mouse body with attached standard metal electrodes (left) and carbon-based electrodes developed by SKYSCAN (right).