objective: the aim of this study was to evaluate the influences of reconstruction and attenuation correction on the differences in the radioactivity distributions in 123i brain spect obtained by the hybrid spect/ct device. methods: we used the 3-dimensional (3d) brain phantom, which imitates the precise structure of gray mater, white matter and bone regions. it was filled with 123i solution (20...

Forty years have passed since the introduction of single-photon emission computed tomography (SPECT)in nuclear cardiology. During this period, there was a shift from Anger-type gamma cameras equipped with one detector to those with multiple detectors. Semiconductor detectors have also become available in recent years. Devices with X-ray CT and positron emission tomography (PET)-compatible ones ...

OBJECTIVES SPECT/slow-rotation low-output CT systems can produce streak artifacts in filtered backprojection (FBP) attenuation maps, impacting attenuation correction (AC) in myocardial perfusion imaging. This paper presents an adaptive Bayesian iterative transmission reconstruction (ABITR) algorithm for more accurate AC. METHODS In each iteration, ABITR calculated a three-dimensional prior co...

We present globally convergent incremental EM algorithms for reconstruction in emission tomography, COSEMML for maximum likelihood and COSEM-MAP for maximum a posteriori reconstruction. The COSEM (Complete data Ordered Subsets Expectation Maximization) algorithms use ordered subsets (OS) for fast convergence, but unlike other globally convergent OS-based ML and MAP algorithms such as RAMLA (Bro...

A 4D ordered-subsets maximum a posteriori (OSMAP) algorithm for dynamic SPECT is described which uses a temporal prior that constrains each voxel's behaviour in time to conform to a compartmental model. No a priori limitations on kinetic parameters are applied; rather, the parameter estimates evolve as the algorithm iterates to a solution. The estimated parameters and time-activity curves are u...

The Expectation Maximization (EM) algorithm [1, 2] is one of the most widely used algorithms in statistics. Suppose we are given some observed data X and a model family parametrized by θ, and would like to find the θ which maximizes p(X |θ), i.e. the maximum likelihood estimator. The basic idea of EM is actually quite simple: when direct maximization of p(X |θ) is complicated we can augment the...

conclusion osem3d may provide better image quality and higher contrast than other methods for small animal imaging with the new myocardial imaging agent, [18f] fptp. results the location and size of myocardial infarction on pet images correlated closely with that observed with ttc staining. among the four reconstruction methods, osem3d provided the best assessment of infarct size (r2 = 0.994, p...