In Vivo Imaging of a Rat Brain Using Photoacoustic Tomography

Secure an anesthetized rat on an imaging bed with its nose and mouth fitted into a mask that delivers an anesthetic agent.

Attach a pulse oximeter to monitor physiological parameters.

Apply ultrasound gel to the scalp, then position the bed under the scanner with the scalp centered under the imaging window.

Raise the bed until the gel contacts the window.

Acquire test images and adjust the bed height to align the brain's cross-sectional plane with the ultrasonic transducer's focus.

Set the imaging parameters and begin scanning.

The imaging system's pulsed-laser diode emits nanosecond light pulses that penetrate the scalp and interact with chromophores, such as hemoglobin.

The absorbed light induces localized heating, generating transient pressure waves called photoacoustic signals.

These signals are captured from multiple angles by the rotating ultrasound transducer.

Using software, process the signals to reconstruct a 2D cross-sectional brain image, highlighting vascular structures.

To begin the imaging procedure, obtain a healthy female rat. Following anesthesia, trim the fur on the scalp with a hair clipper. Gently apply depilatory cream to the trimmed area. After four to five minutes, r