Approach of trans-rectal NIR optical tomography probing for the imaging of prostate with trans-rectal ultrasound correlation

The trans-rectal implementation of NIR optical tomography makes it possible to assess functional status like hemoglobin concentration and oxygen saturation in prostate non-invasively. Trans-rectal NIR tomography may provide tissue-specific functional contrast that is potentially valuable for differentiation of cancerous lesions from normal tissues. Such information will help to determine if a prostate biopsy is needed or can be excluded for an otherwise ambiguous lesion. The relatively low spatial resolution due to the diffuse light detection in trans-rectal NIR tomography, however, limits the accuracy of localizing a suspicious tissue volume. Trans-rectal ultrasound (TRUS) is the clinical standard for guiding the positioning of biopsy needle owing to its resolution and convenience; nevertheless, TRUS lacks the pathognomic specificity to guide biopsy to only the suspicious lesions. The combination of trans-rectal NIR tomography with TRUS could potentially give better differentiation of cancerous tissue from normal background and to accurately localize the cancer-suspicious contrast obtained from NIR tomography. This paper will demonstrate the design and initial evaluation of a trans-rectal NIR tomography probe that can conveniently integrate with a commercial TRUS transducer. The transrectal NIR tomography obtained from this probe is concurrent with TRUS at matching sagittal imaging plane. This design provides the flexibility of simple correlation of trans-rectal NIR with TRUS, and using TRUS anatomic information as spatial prior for NIR image reconstruction.