The statistical evaluation of molecular imaging approaches for detecting, diagnosing,
and monitoring molecular response to treatment are required prior to their adoption. The
assessment of fluorescence-enhanced optical imaging is particularly challenging since
neither instrument nor agent has been established. Small animal imaging does not
address the depth of penetration issues adequately and the risk of administering
molecular optical imaging agents into patients remains unknown. Herein, we focus
upon the development of a framework for OAIQ which includes a lumpy-object model
to simulate natural anatomical tissue structure as well as the non-specific distribution of
fluorescent contrast agents. This work is required for adoption of fluorescence-enhanced
optical imaging in the clinic.
Herein, the imaging system is simulated by the diffusion approximation of the
time-dependent radiative transfer equation, which describes near infra-red light
propagation through clinically relevant volumes. We predict the time-dependent light
propagation within a 200 cc breast interrogated with 25 points of excitation illumination
and 128 points of fluorescent light collection. We simulate the fluorescence generation
from Cardio-Green at tissue target concentrations of 1, 0.5, and 0.25 µM with backgrounds containing 0.01 µM. The fluorescence boundary measurements for 1 cc
spherical targets simulated within lumpy backgrounds of (i) endogenous optical
properties (absorption and scattering), as well as (ii) exogenous fluorophore crosssection
are generated with lump strength varying up to 100% of the average background.
The imaging data are then used to validate a PMBF/CONTN tomographic reconstruction
algorithm. Our results show that the image recovery is sensitive to the heterogeneous
background structures. Further analysis on the imaging data by a Hotelling observer
affirms that the detection capability of the imaging system is adversely affected by the
presence of heterogeneous background structures. The above issue is also addressed
using the human-observer studies wherein multiple cases of randomly located targets
superimposed on random heterogeneous backgrounds are used in a “double-blind”
situation. The results of this study show consistency with the outcome of above
mentioned analyses. Finally, the Hotelling observer’s analysis is used to demonstrate (i)
the inverse correlation between detectability and target depth, and (ii) the plateauing of
detectability with improved excitation light rejection.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1068 |
| Date | 15 May 2009 |
| Creators | Sahu, Amit K. |
| Contributors | El-Halwagi, Mahmoud, Sevick-Muraca, Eva M. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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