High resolution optical projection tomographic microscopy for 3D tissue imaging

Optical projection tomography (OPT) requires a large depth of field (DOF) of a low numerical aperture (NA) lens resulting in low resolution. However, DOF of a high NA objective can be extended by scanning the focal plane through the sample. This extended DOF image is called pseudoprojection, which is used by optical projection tomographic microscope (OPTM) for tomographic reconstruction. The advantage of OPTM is the acquisition of relatively high resolution and large depth of field concurrently. This method requires the working distance of the lens to be larger than the size of the sample, so proper lens should be chosen for samples of different sizes. In this paper, we imaged hematoxylin stained muntjac cells inside capillary tube with two different sizes. Two objective lenses with different NA are used for these two tubes. Experimental results show that resolution improves over 10 times in OPTM compared to conventional OPT, which make it possible for OPTM technique to resolve sub-cellular features for large samples. Therefore, OPTM can be used for 3D histological analysis of hematoxylin & eosin (H&E) stained biopsy specimen with sub-cellular resolution in the future.