In vivo validation of quantitative frequency domain fluorescence tomography

Abstract

We have developed a hybrid frequency domain fluorescence tomography and magnetic resonance imaging system (MRI) for small animal imaging. The main purpose of this system is to obtain quantitatively accurate fluorescence concentration and lifetime images using a multi-modality approach. In vivo experiments are undertaken to evaluate the system. We compare the recovered fluorescence parameters with and without MRI structural a priori information. In addition, we compare two optical background heterogeneity correction methods: Born normalization and utilizing diffuse optical tomography (DOT) functional a priori information. The results show that the concentration and lifetime of a 4.2-mm diameter indocyanine green inclusion located 15 mm deep inside a rat can be recovered with less than a 5% error when functional a priori information from DOT and structural a priori information from MRI are utilized.

Fig. 1

(a) Optic fiber interface integrated with a birdcage MRI coil; (b) the schematic diagram of the frequency-domain FT system.

Fig. 2

The results for different combinations of functional a priori information. The MRI image of the animal is shown at the top of the figure. The ICG inclusion is indicated by the arrow and can be identified as the dark circle in the MR image. The reconstructed images for each case, with and without MR a priori information is provided.