Qualitative and quantitative evaluation of in vivo SD-OCT measurement of rat brain.

OCT has been demonstrated as an efficient imaging modality in various biomedical and clinical applications. However, there is a missing link with respect to the source of contrast between OCT and other modern imaging modalities, no quantitative comparison has been demonstrated between them, yet. We evaluated, to our knowledge, for the first time in vivo OCT measurement of rat brain with our previously proposed forward imaging method by both qualitatively and quantitatively correlating OCT with the corresponding T1-weighted and T2-weighted magnetic resonance images, fiber density map (FDM), and two types of histology staining (cresyl violet and acetylcholinesterase AchE), respectively. Brain anatomical structures were identified and compared across OCT, MRI and histology imaging modalities. Noticeable resemblances corresponding to certain anatomical structures were found between OCT and other image profiles. Correlation was quantitatively assessed by estimating correlation coefficient (R) and mutual information (MI). Results show that the 1-D OCT measurements in regards to the intensity profile and estimated attenuation factor, do not have profound linear correlation with the other image modalities suggested from correlation coefficient estimation. However, findings in mutual information analysis demonstrate that there are markedly high MI values in OCT-MRI signals.