State Sovereign Immunity and Intellectual Property: An Evaluation of the Trademark Remedy Clarification Act’s Attempt to Subject States to Suit in Federal Courts for Trademark Infringements Under the Lanham Act

There are two things that can be learned from this paper. First, the analytical framework developed by the Court in City of Boerne is a stringent test that has considerably narrowed Congress’s ability to abrogate state’s Eleventh Amendment immunity through legislation. Second, only half of the battle was won when Congress enacted the Trademark Remedy Clarification Act. Although it met the new requirements the Court placed on legislative efforts in Atascadero, it is not able to meet the requirements that were later set forth in Seminole Tribe. The Rehnquist Court’s holdings indicate the Court’s active pursuit of state’s rights. These decisions have interpreter the Fourteenth Amendment very narrowly. Under this line of reasoning the TRCA would fail again if it were to be evaluated

A Simple Penalty that Encourages Local Invertibility and Considers Sliding Effects for Respiratory Motion

Nonrigid image registration is a key tool in medical imaging. Because of high degrees of freedom in nonrigid transforms, there have been many efforts to regularize the deformation based on some reasonable assumptions. Especially, motion invertibility and local tissue rigidity have been investigated as reasonable priors in image registration. There have been several papers on exploiting each constraint separately. These constraints are reasonable in respiratory motion estimation because breathing motion is invertible and there are some rigid structures such as bones. Using both constraints seems very attractive in respiratory motion registration since using invertibility prior alone usually causes bone warping in ribs. Using rigidity prior seems natural and straightforward. However, the “sliding effect” near the interface between rib cage and diaphragm makes problem harder because it is not locally invertible. In this area, invertibility and rigidity priors have opposite forces. Recently, we proposed a simple piecewise quadratic penalty that encourages the local invertibility of motions. In this work we relax this penalty function by using a Geman-type function that allows the deformation to be piecewise smooth instead of globally smooth. This allows the deformation to be discontinuous in the area of the interface between rib cage and diaphragm. With some small sacrifice of regularity, we could achieve more realistic discontinuous motion near diaphragm, better data fitting error as well as less bone warping. We applied this Geman-type function penalty only to the x- and y-direction partial derivatives of the z-direction deformation to address the sliding effect. 192 × 128 × 128 3D CT inhale and exhale images of a real patient were used to show the benefits of this new penalty method.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85922/1/Fessler238.pd

Feasibility Study of Compton Scattering Enchanced Multiple Pinhole Imager for Nuclear Medicine

This paper presents a feasibility study of a Compton scattering enhanced (CSE) multiple pinhole imaging system for gamma rays with energy of 140 keV or higher. This system consists of a multiple-pinhole collimator, a position sensitive scintillation detector as used in a standard gamma camera, and a Si pad detector array, inserted between the collimator and the scintillation detector. The problem of multiplexing, normally associated with multiple pinhole system, is reduced by using the extra information from the detected Compton scattering events. In order to compensate for the sensitivity loss, due to the low probability of detecting Compton scattered events, the proposed detector is designed to collect both Compton scattering and non-Compton events. It has been shown that with properly selected pinhole spacing, the proposed detector design leads to an improved image quality.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86012/1/Fessler64.pd

Spectral Analysis Using Regularized Non-Negative Least-Squares Estimation

The implementation of spectral analysis techniques involves solving a highly underdetermined linear system equation and is prone to the effect of measurement noise. The authors propose to use a regularized non-negative least-square estimator to stabilize the implementation of the technique. They introduce a penalty term in their formulation of the function to discourage disparities in tracer kinetics between neighboring pixels and use an iterative method to impose positivity constraints. The authors show results from analysis of FDG thorax images of patients suspected to have cancers and summarize their findings.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85892/1/Fessler137.pd

Bias-Variance Tradeoffs Analysis Using Uniform CR Bound For a SPECT System

The authors quantify fundamental bias-variance tradeoffs for the image reconstruction problem in radio-pharmaceutical tomography using Cramer-Rao (CR) bound analysis. The image reconstruction problem is very often biased and the classical or the unbiased CR bound on the mean square error performance of the estimator can not be used. The authors use a recently developed “uniform” CR bound which applies to biased estimators whose bias gradient satisfies a user specified length constraint. The authors demonstrate the use of the “uniform” CR bound for a simple SPECT system using several different examples.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85970/1/Fessler126.pd

Improved Modeling of System Response in List Mode EM Reconstruction of Compton Scatter Camera Images

An improved List Mode EM method for reconstructing Compton scattering camera images has been developed. First, an approximate method for computation of the spatial variation in the detector sensitivity has been derived and validated by Monte Carlo computation. A technique for estimating the relative weight of system matrix coefficients for each gamma in the list has also been employed, as has a method for determining the relative probabilities of emission having come from pixels tallied in each list-mode back-projection. Finally, a technique has been developed for modeling the effects of Doppler broadening and finite detector energy resolution on the relative weights for pixels neighbor to those intersected by the back-projection, based on values for the FWHM of the spread in the cone angle computed by Monte Carlo. Memory issues typically associated with list mode reconstruction are circumvented by storing only a list of the pixels intersected by the back-projections, and computing the weights of the neighboring pixels at each iteration step. Reconstructions have been performed on experimental data for both point and distributed sourcesPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86026/1/Fessler77.pd

Transmission Imaging With Axially Overlapping Cone-Beams

We have shown that cone-beam transmission imaging of medium-energy photons that penetrate the parallel-hole collimators can be used to rapidly estimate attenuation maps for use in reconstruction of cardiac SPECT images. Such a transmission imaging geometry offers the advantages of eliminating the need to mechanically move the point-sources during imaging, and minimizes cross-talk between emission and transmission imaging. The axial extent over which artifact-free attenuation maps can be reconstructed is limited by the cone-beam geometry and source collimation. We investigated irradiation of a single head by multiple point-sources such that their asymmetric cone-beam fields overlap in the axial direction as a method of extending the axial coverage of the patient. This study reports on testing of a penalized-likelihood algorithm for transmission reconstruction of overlapping cone-beams. This algorithm was evaluated through MCAT simulations and applied to transmission measurements of an anthropomorphic phantom. The experimental work consisted of performing a series of flood and transmission measurements on the anthropomorphic phantom with shifted axial locations of point-sources. We summed the projection data from individual measurements to simulate the projection data for a multiple point-source system. With the proposed penalized-Iikelihood algorithm, the full axial extent (20.5 cm) of the anthropomorphic phantom was reconstructed for the overlapping cone-beam geometry with 2 point-sources per camera head.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85904/1/Fessler202.pd

Preliminary Studies on the Feasibility of Addition of Vertex View to Conventional Brain SPECT

We have investigated the improvement in resolution and sensitivity for brain imaging which would result by the addition of a single stationary vertex view to the tomographic data. This method has the practical advantage of being relatively inexpensive and easy to implement. The uniform Cramer Rao bound is a plot of the minimum achievable standard deviation for estimating the pixel intensity as a function of the bias gradient length. Uniform CR bound analysis indicated an improvement in performance when the vertex detector is added, especially for centrally located pixels for which improvement is seen over the useful depth for brain imaging. Simulation experiments were done with a simple six slice phantom and with the Hoffman brain phantom. Visual inspection of the reconstructed images showed improved resolution and noise characteristics over reconstructed images without the vertex data. Quantitatively, substantial reduction in mean square error was observed for a plane close to the vertex detector. Improvement reduced as distance from the vertex detector is increased. Background activities inside the field of view of the vertex detector but not the tomograph were represented by several blobs of activity on a plane lying outside the reconstruction volume. This activity was estimated by 3D spline fitting jointly with the image reconstruction process. Adding the vertex view to conventional brain SPECT should lead to improved cortical imaging, and to moderate improvement for deep structures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85857/1/Fessler142.pd