A multi-spectral, portable, hand-held LED based spatial frequency domain imaging system was used for ex vivo imaging pretreatment and post treatment human colon and rectal tissues. Freshly excised human colon and rectal tissue samples were imaged with the hand-held SFDI probe with 9 wavelengths extending from visible to NIR (660-950 nm). Important tumor biomarkers such as hemoglobin, scatter amplitude, scatter spectral slope, water and lipid content were quantitatively extracted from the SFDI absorption and scattering images. Significant differences were observed between the absorption as well as scattering distribution of normal, tumor and polyp tissue as well as between pretreated and post-treated tumors.
Colorectal cancer is the second most common malignancy diagnosed globally. Critical need exists for imaging and diagnosis of rectal tumors for both staging and therapeutic response evaluations. We have conducted a pilot study to image and characterize colorectal masses using a real-time co-registered photoacoustic (PAT) and ultrasound (US) system. A total of 8 tissue samples including pre- and post-treatment colorectal cancer, polyps have studied. Four different wavelengths (730, 780, 800, 830 nm) were used to illuminate the sample and a scanning stage was used to scan a large area and obtain a sequence of B-scans. For the pre-treatment colorectal cancer, photoacoustic images have shown significantly higher vascular level than neighbor benign regions of the same sample. The pre-treatment colorectal cancer PAT signal level is also higher than polyps and post-treatment colorectal cancer. Additionally, the quantitative features extracted from PAT and US power spectrum such as spectral slope, mid-band fit and zero MHz intercept have shown statistical significance between pre-treatment colorectal cancer and other 3 categories using t-test. Our initial results have demonstrated that PAT/US has a great potential to reveal tumor angiogenesis development or residual tumors after treatment.