Functional imaging in small animals using X-ray computed tomography--study of physiologic measurement reproducibility

Area of Science:

• Medical Imaging
• Physiology
• Biophysics

Background:

• X-ray computed tomography (CT) traditionally used for morphology, now applied to physiology imaging.
• Functional CT offers insights into disease processes and therapeutic interventions at cellular and molecular levels.
• Understanding the impact of imaging parameters on physiological measurements is crucial for accurate in vivo studies.

Purpose of the Study:

• To demonstrate functional CT as an effective tool for monitoring tissue physiology changes.
• To investigate the influence of noise and sampling time on the accuracy of tissue physiological parameters.
• To determine optimal scanning protocols for experimental studies using small animal functional X-ray CT.

Main Methods:

• A whole-body compartmental model of a mouse was developed to simulate tissue time-density curves.
• Dynamic contrast-enhanced CT (DCE-CT) experiments were conducted in mice using varying contrast agent injection rates and X-ray tube currents.
• A two-compartment model (2CM) was employed to analyze contrast kinetics in the kidney cortex, extracting parameters like renal blood flow and glomerular filtration rate.

Main Results:

• The study determined the effects of noise and sampling time on the uncertainty of tissue physiological parameters.
• Experimental results showed that deviations in physiological parameters were within acceptable limits for in vivo disease tracking.
• Optimized scanning protocols were proposed based on the Nyquist sampling limit and noise level investigations.

Conclusions:

• Small animal functional X-ray CT is a viable method for assessing in vivo tissue physiology changes.
• The findings support the use of functional CT for monitoring disease progression and therapeutic responses.
• This research provides a foundation for developing more precise and reliable functional CT imaging protocols.