This study has investigated the relationship between linear attenuation coefficients (mu) and Hounsfield units (HUs) for six materials covering the range of values found clinically. Narrow-beam mu values were measured by performing radionuclide transmission scans using (99m)Tc, (123)I, (131)I, (201)Tl and (111)In. The mu values were compared to published data. The relationships between mu and H...

T his statement of the Committee on Advanced Cardiac Imaging and Technology of the Council on Clinical Cardiology addresses the use of positron emission tomography (PET) as a clinical tool for the diagnosis and management of patients with coronary artery disease. Over the past decade PET technology has evolved to the point that clinical PET studies can be performed safely and efficiently in the...

In single photon emission computed tomography (SPECT) one is interested in reconstructing the activity distribution f of some radiopharmaceutical. The data gathered suffer from attenuation due to the tissue density μ. Each imaged slice incorporates noisy sample values of the nonlinear attenuated Radon transform A(f,μ)(ω, s) = ∫ ∞ −∞ f (sω⊥ + tω) exp (

INTRODUCTION There has been recently great interest in combining PET and MRI, and a number of integrated scanners capable of simultaneous acquisition have been developed and successfully tested for small animal [1,2] and human [3] imaging. Correcting for photon attenuation in PET is an important and required step not only for quantitative studies, but also for performing meaningful qualitative ...

Despite advancements in technologies, non-uniform soft tissue attenuation still affects the diagnostic accuracy of single photon emission computed tomography (SPECT) myocardial perfusion imaging. A variety of indirect measures have been used to reduce the impact of attenuation, most notably electrocardiography-gated SPECT imaging. However, all available techniques have limitations, making inter...

This paper addresses the application of optimization transfer to simultaneous statistical estimation of attenuation and activity images in tomographic image reconstruction. Although the technique we propose has wider applicability, we focus on the problem of reconstructing from data acquired via a post-injection transmission scan protocol. In this protocol, emission scan data is supplemented wi...

BACKGROUND Attenuation correction of a single photon emission computed tomography (SPECT) image is possible using computed tomography (CT)-based attenuation maps with hybrid SPECT/CT. CT attenuation maps acquired during breath holding can be misaligned with SPECT, generating artifacts in the reconstructed images. The purpose of this study was to investigate the effects of respiratory phase duri...

Optical computed tomography (optical-CT) and optical-emission computed tomography (optical-ECT) are new techniques for imaging the 3D structure and function (including gene expression) of whole unsectioned tissue samples. This work presents a method of improving the quantitative accuracy of optical-ECT by correcting for the 'self'-attenuation of photons emitted within the sample. The correction...

The purpose of this paper is to introduce the principles of PET/CT imaging and describe the artifacts associated with it. PET/CT is a new imaging modality that integrates functional (PET) and structural (CT) information into a single scanning session, allowing excellent fusion of the PET and CT images and thus improving lesion localization and interpretation accuracy. Moreover, the CT data can ...

BACKGROUND Soft tissue attenuation is a prominent cause of single-photon emission computed tomography (SPECT) imaging artifacts, which may result in reduced diagnostic accuracy of myocardial perfusion imaging. A method incorporating simultaneously acquired transmission data permits nonuniform attenuation correction and when incorporating scatter correction and resolution compensation may substa...