Roy Ranadhir, Godavarty Anuradha, Sevick-Muraca Eva M
The Photon Migration Laboratories, Texas A&M University, College Station, TX 77843-3573, USA.
IEEE Trans Med Imaging. 2003 Jul;22(7):824-36. doi: 10.1109/TMI.2003.815072.
A three-dimensional image reconstruction for fluorescence-enhanced frequency-domain photon migration (FDPM) measurements in turbid media is developed and investigated for three different simulated measurement types: 1) absolute emission measurement, or emission measurements of phase and amplitude attenuation made for a given incident point source of excitation light; 2) referenced emission measurements made relative to an excitation measurement conducted at a single reference point away from the incident source; and 3) referenced emission measurements made relative to the excitation measurement conducted at identical points of detection. The image reconstruction algorithm employs a gradient-based constrained truncated Newton (CONTN) method which implements a bounding parameter, which can be used to govern the level of contrast used to discriminate tissue volumes from heterogeneous background tissues. Reverse differentiation technique is used to calculate the gradients. Using simulated data with superimposed noise to achieve a signal-to-noise ratio of 55 and 35 dB to mimic experimental excitation and emission FDPM measurements, respectively, we show the robustness of emission measurements referenced to excitation light. We investigate the performance of algorithm CONTN using these measurement techniques and show that the absorption coefficients due to fluorophore are reconstructed by CONTN accurately and efficiently. Furthermore, we demonstrate the performance of the bounding parameter for rejection of background artifacts owing to background tissue heterogeneity.
针对混浊介质中的荧光增强频域光子迁移（FDPM）测量，开发并研究了一种三维图像重建方法，用于三种不同的模拟测量类型：1）绝对发射测量，即对给定的激发光入射点源进行的相位和幅度衰减的发射测量；2）相对于在远离入射源的单个参考点进行的激发测量的参考发射测量；3）相对于在相同检测点进行的激发测量的参考发射测量。图像重建算法采用基于梯度的约束截断牛顿（CONTN）方法，该方法实现了一个边界参数，可用于控制用于区分组织体积与异质背景组织的对比度水平。使用反向微分技术计算梯度。分别使用叠加噪声的模拟数据，以实现55 dB和35 dB的信噪比，来模拟实验激发和发射FDPM测量，我们展示了参考激发光的发射测量的稳健性。我们使用这些测量技术研究了CONTN算法的性能，并表明CONTN能准确有效地重建由于荧光团引起的吸收系数。此外，我们展示了边界参数在抑制由于背景组织异质性导致的背景伪影方面的性能。
