Trans-rectal ultrasound-coupled near-infrared optical tomography of the prostate, Part I: Simulation

Abstract

We investigate the feasibility of trans-rectal optical tomography of the prostate using an endo-rectal near-infrared (NIR) applicator that is to be integrated with a trans-rectal ultrasound (TRUS) probe. Integration with TRUS ensures accurate endo-rectal positioning of the NIR applicator and the utility of using TRUS spatial prior information to guide NIR image reconstruction. The prostate NIR image reconstruction is challenging even with the use of spatial prior owing to the anatomic complexity of the imaging domain. A hierarchical reconstruction algorithm is developed that implements cascaded initial-guesses for nested domains. This hierarchical image reconstruction method is then applied to evaluating a number of NIR applicator designs for integration with a sagittal TRUS transducer. A NIR applicator configuration feasible for instrumentation development is proposed that contains one linear array of optodes on each lateral side of the sagittal TRUS transducer. The performance of this NIR applicator is characterized for the recovery of single tumor mimicking lesion as well as dual targets in the prostate. The results suggest a strong feasibility of transrectal prostate imaging by use of the endo-rectal NIR/US probe.

Diffuse optical tomography to monitor the photocoagulation front during interstitial photothermal therapy: Numerical simulations and measurements in tissue-simulating phantoms

“…The experimentally tested configuration was originally designed for whole prostate imaging [23][24][25]. With its large field of view, lesion monitoring is relatively insensitive to probe placement.…”

“…A variety of DOT systems have been reported for functional imaging or tumor detection, including in the breast [18][19][20] and brain [21,22]. Of particular relevance here is a system that combined continuous-wave (CW) transrectal diffuse optical tomography (CW-TRDOT) with twodimensional (2-D) TRUS for prostate cancer detection and quantification, based on the tumor having higher optical absorption than normal prostate in the NIR [23][24][25]. Tumor imaging was successfully demonstrated in a canine prostate cancer model [24] using this system.…”

“…Using an existing DOT system [23,25], DOT sensitivity was tested with measurements made on a set of phantoms of varying optical contrast and lesion size. The results were then cross-validated against forward simulations using finite element solutions to diffusion theory.…”

Information theoretic regularization in diffuse optical tomography

“…As in [Schweiger and Arridge, 1999b], by restricting all pixels in the optical domain belonging to the same tissue type to be completely correlated, the underdetermined problem of DOT becomes overdetermined as the number of unknowns drops dramatically. Jiang et al [2008]; Xu et al [2008] used the method to incorporate prior information in trans-rectal ultrasound imaging (UI) driver, DOT imaging. Pogue and Paulsen [1998] used the information from a segmented coronal MRI slice acquired from a rat, in order to create a realistic finite element mesh based numerical phantom to be probed.…”

Volumetric Diffuse Optical Tomography for Small Animals Using a CCD-Camera-Based Imaging System

“…This technique has been investigated for several clinical applications, particularly for monitoring of functional brain activities [3][4][5] and detection of breast cancer [6,7]. The fundamental principle of DOT is that the detected NIR signals reflect optical properties of the underlying biological tissues [8,9] and that the spatial distribution of such measured optical properties can be used to reconstruct optical tomographic images.…”