Experimental Imaging

Methods

High-field MRI examinations in the small animal

The magnetic resonance imaging examination (MRI) is one of the most important diagnostic measures in the examination of living animals. Working together with the Diagnostic Radiology Clinic at the University of Leipzig, the unit carries out examinations using 1.5 and 3 Tesla systems. A 7T small-animal scanner can be used for high resolutions. The range of methods is extensive and includes most standard sequences. They can be adjusted to the task if necessary.

Bioluminescence and biofluorescence imaging

This technology is based on capturing photochemical light emissions of self-luminous or stimulated fluorescent dyes in the living animal. The most common way of achieving this is to genetically introduce a vector for the luciferase enzyme into the cell being examined and then stimulate this cell to emit light by adding luciferin. If the respectively marked cells are now applied to a small animal, they can be detected in vivo by a highly sensitive CCD camera from a given concentration, even over longer periods of time. The IVIS spectrum imaging system used for this purpose shows a high level of sensitivity in the examination range of 400 and 900 nm.

Confocal laser scanning microscopy

3D image of scar formation after stroke
© Fraunhofer IZI
3D image of scar formation after stroke.

In this unit, the qualitative and quantitative analysis of fluorescence-dyed samples is conducted using a confocal microscope (Zeiss LSM710). This microscopic technology allows non-overlapping recordings of specific signals in tissues or cell cultures. For further processing and 3D image analysis, the acquisition of images is complemented by the complex software package IMARIS.

Stereology

Stereological counts are the gold standard for error-free quantitative analyses in tissues. By using different algorithms it is possible to quantify object frequencies, surfaces and volumes as well as lengths and branching degrees of structures.

Imaging examination with clinical scanners and their evaluation

3D Reconstruction of skin and bone tissue of a sheep's head based on a CTI data set
© Fraunhofer IZI
3D Reconstruction of skin and bone tissue of a sheep's head based on a CTI data set.

Together with partners from the University of Leipzig, the majority of imaging techniques established in human medicine were adapted in order to examine large-animal models. This concerns both anatomical (computer tomography) and anatomical-functional (magnetic resonance imaging) examinations. Beyond this, metabolic processes can be visualized by means of positron emission tomography. The most varied quantifying evaluation routines permit an exact assessment of the change.