Model-based system matrix for iterative reconstruction in sub-diffuse angular-domain fluorescence optical projection tomography

Abstract

This work concerns a fluorescence optical projection tomography system for low scattering tissue, like lymph nodes, with angular-domain rejection of highly scattered photons. In this regime, filtered backprojection (FBP) image reconstruction has been shown to provide reasonable quality images, yet here a comparison of image quality between images obtained by FBP and iterative image reconstruction with a Monte Carlo generated system matrix, demonstrate measurable improvements with the iterative method. Through simulated and experimental phantoms, iterative algorithms consistently outperformed FBP in terms of contrast and spatial resolution. Moreover, when projection number was reduced, in order to reduce total imaging time, iterative reconstruction suppressed artifacts that hampered the performance of FBP reconstruction (structural similarity of the reconstructed images with “truth” was improved from 0.15 ± 1.2 × 10−3 to 0.66 ± 0.02); and although the system matrix was generated for homogenous optical properties, when heterogeneity (62.98 cm-1 variance in µs) was introduced to simulated phantoms, the results were still comparable (structural similarity homo: 0.67 ± 0.02 vs hetero: 0.66 ± 0.02).

Fluorescence mesoscopic imaging of whole lymph nodes for intraoperative sentinel lymph node biopsy procedures

“…Although full 3D simulation was carried out, only one 2D slice was then reconstructed at the height of the micrometastases (for simplicity) using filtered back-projection (FBP) (16), and an iterative approach using Monte Carlo simulations as models of photon propagation as described in (17). For each configuration and 100 FBP-reconstructed images, we evaluated micrometastasis detectability in a signal-known-exactly (SKE), location-known-exactly (LKE) paradigm (26) and SKE, multiple-alternative forced choice (MAFC) localization where we simulated 15 random, nonoverlapping locations where one of them contained signal (26).…”

“…The approach is to use paired-agent molecular imaging principles-where a control imaging agent is co-administered with a cancer-targeted agent as a means of accounting for delivery variability and nonspecific accumulation of the targeted agent (10,11)-and narrow aperture fluorescence tomography for whole excised node rapid imaging. To date, our group has built a prototype of the narrow aperture fluorescence imaging system that we have coined ADEPT (agent dependent early photon tomography) and demonstrated the ability to detect "micrometastases" in pig nodes (12)(13)(14)(15)(16)(17), and identified a method for staining and rinsing whole excised lymph nodes with our paired imaging agents (18,19). In this work, all the information we have gathered characterizing our system, data analysis procedures, imaging agent properties, and tissue optical properties were used to develop an accurate simulation model to explore the potential accuracy and precision of detecting clinically relevant levels of cancer in excised lymph nodes.…”

Fluorescence molecular imaging using cetuximab-800CW in cutaneous squamous cell carcinoma surgery: a proof-of-concept study

“…However, it seems less useful for keratoacanthoma‐like cSCC or in patients with excessive actinic damage. Future studies should determine the clinical value of FMI in surgery of high‐risk cSCCs, ideally with new imaging methodologies that deliver improved depth information 8 …”

“…Future studies should determine the clinical value of FMI in surgery of high‐risk cSCCs, ideally with new imaging methodologies that deliver improved depth information. 8 …”

“…Future studies should determine the clinical value of FMI in surgery of high-risk cSCCs, ideally with new imaging methodologies that deliver improved depth information. 8 Bread loaf sections provide useful information on more than 0Á5% of surgical margins DOI: 10.1111/bjd.21740 DEAR EDITOR, Some authors assert that 'bread loaf' analysis of specimens with step sections assesses <0Á5% of the surgical margin and that conventional histological resection margin control is an illusion. 1,2 The high cure rates of >90% reported for simple excision of small, low-risk basal cell carcinomas led us to consider the mathematics further.…”