Assessing the impact of radiation-induced changes in soft tissue density ∕ thickness on the study of radiation-induced perfusion changes in the lung and heart.

Purpose: Abnormalities in single photon emission computed tomography (SPECT) perfusion within the lung and heart are often detected following radiation for tumors in∕around the thorax (e.g., lung cancer or left-sided breast cancer).

Slit-Slat and Multislit-Slat Collimator Design and Experimentally Acquired Phantom Images from a Rotating Prototype.

We have previously found and validated expressions for slit-slat (SS) geometric efficiency and resolution. These expressions have suggested that SS may be a good choice for imaging mid-size objects or objects that are long axially since (i) the geometric efficiency increases near the slit as h(-1) (instead of h(-2) for pinhole (PIN) and either decreases near the collimator for fan-beam (FB) or remains constant for parallel-beam (PB)), where h is the distance from a point to the slit plane; (ii) the transverse resolution is comparable to that of PIN, which is better than that of FB and PB for small objects; (iii) the axial resolution is worse than that of PIN since there is no axial magnification; (iv) there is a large axial FOV, unlike PIN, which is likely to be useful when imaging mid-size or long objects; and (v) there is no need for 3D orbits (e.g.

Quantitative Evaluation of Half-Cone-Beam Scan Paths in Triple-Camera Brain SPECT.

In this study related to human brain SPECT imaging, simulation of half-cone-beam (HCB) collimation with different scan paths is performed and compared with simulated fan-beam and parallel-hole circular orbit acquisitions of disk-phantom projection data. Acquisition types are quantitatively evaluated based on the photon detection efficiency, the root-mean-squared error, contrast and signal-to-noise ratio measurements of the reconstructed images. We demonstrate that a triple-camera SPECT system with half-cone-beam collimators and circle-and-helix scan paths can offer up to a 26% efficiency increase over fan-beam, and up to a 128% increase over parallel-hole collimators for equal spatial resolutions, and display no visible axial sampling artifacts in reconstructed disk-phantom images.

Combination of converging collimators for high-sensitivity brain SPECT.

Unlabelled: The objective of this study, which is related to human brain SPECT, was to increase the sensitivity of a triple-camera SPECT system and reduce statistical noise in reconstructed images using a combination of converging collimators. The reason for combining collimators is to ensure both high sensitivity and sufficient sampling without trading off spatial resolution.

Methods: A high-sensitivity half-cone-beam (HCB) collimator, designed specifically for brain imaging, was combined with other collimators and compared with conventional parallel-beam and fanbeam circular orbit acquisitions.

Radiation-induced reductions in regional lung perfusion: 0.1-12 year data from a prospective clinical study.

Purpose: To assess the time and regional dependence of radiation therapy (RT)-induced reductions in regional lung perfusion 0.1-12 years post-RT, as measured by single photon emission computed tomography (SPECT) lung perfusion.

Materials/methods: Between 1991 and 2005, 123 evaluable patients receiving RT for tumors in/around the thorax underwent SPECT lung perfusion scans before and serially post-RT (0.

Feasibility of whole-body functional mouse imaging using helical pinhole SPECT.

Purpose: Detailed in vivo whole-body biodistributions of radiolabeled tracers may characterize the longitudinal progression of disease, and changes with therapeutic interventions. Small-animal imaging in mice is particularly attractive due to the wide array of well characterized genetically and surgically created models of disease. Single Photon Emission Computed Tomography (SPECT) imaging using pinhole collimation provides high resolution and sensitivity, but conventional methods using circular acquisitions result in severe image truncation and incomplete sampling of data, which prevent the accurate determination of whole-body radiotracer biodistributions.

Brain SPECT Simulation Using Half-Cone-Beam Collimation and Single-Revolution Helical-Path Acquisition.

In this study related to human brain SPECT imaging, simulation of half-cone-beam collimation and helical-path data acquisition is performed. We discuss problems related to circular-orbit acquisition using cone-beam collimation, such as shoulder interference resulting in object truncation, and insufficient sampling of the object resulting in axial distortions in the reconstructed images. We demonstrate that a triple-camera SPECT system with half-cone-beam collimation and single-revolution helical-path acquisition eliminates both issues and offers substantially improved sampling and almost artifact-free reconstruction of the object.

Left ventricular functional assessment in mice: feasibility of high spatial and temporal resolution ECG-gated blood pool SPECT.

Purpose: To prospectively determine feasibility of evaluating murine left ventricular (LV) function with electrocardiographically (ECG)-gated blood pool single photon emission computed tomography (SPECT).

Materials And Methods: All animal studies had institutional animal care and use committee approval. SPECT was performed with conventional time-binned acquisition (eight frames per ECG cycle) in normal mice (normal group A, n = 6) and mice with myocardial infarction (MI) (n = 8).

Cell therapy in murine atherosclerosis: in vivo imaging with high-resolution helical SPECT.

Purpose: To determine the feasibility of in vivo localization and quantification of indium 111 (111In)-oxine-labeled bone marrow (BM) with high-resolution whole-body helical single photon emission computed tomography (SPECT) in an established murine model of atherosclerosis and vascular repair.

Materials And Methods: The institutional animal care and use committee approved this study. BM from young B6 Rosa 26 Lac Z+/+ mice was radiolabeled with 111In-oxine.

On-axis sensitivity and resolution of a slit-slat collimator.

Unlabelled: A slit-slat collimator combines a slit along the axis of rotation with a set of axial septa, offering both magnification in the transaxial direction and complete sampling with just a circular orbit. This collimator has a sensitivity that increases for points near the aperture slit. The literature treats this collimator as having the same sensitivity as a single-pinhole collimator, ignoring the effect of the axial septa.

The early years of single photon emission computed tomography (SPECT): an anthology of selected reminiscences.

The origin of SPECT can be found in pioneering experiments on emission tomography performed approximately 50 years ago. This historical review consists of a compilation of first person recollections from nine trailblazing scientists who shaped the early years of SPECT instrumentation during the 1960s and 1970s.

Mammotomography with pinhole incomplete circular orbit SPECT.

Unlabelled: Dedicated mammotomography with pinhole incomplete circular orbit (PICO) SPECT imaging of an uncompressed pendant breast was evaluated with small, very-high-stopping-power pinhole apertures. Comparisons were made with planar pinhole scintimammography. Enhanced 3-dimensional imaging performance with very-high-stopping-power apertures is thought to ultimately yield improved sensitivities for lesion detection and identification in breast disease.

Receiver operating characteristic curves to assess predictors of radiation-induced symptomatic lung injury.

Purpose: To assess the utility of dosimetric/functional metrics as predictors of symptomatic radiation pneumonitis using receiver operating characteristic curves.

Methods: Between 1991 and 1999, 277 patients were enrolled on a prospective clinical study to relate radiation therapy (RT) induced changes in lung function with dosimetric and functional metrics. Pre-RT whole and regional functional assessments included pulmonary function tests and single photon emission computed tomography lung perfusion scans.

The time course of radiation therapy-induced reductions in regional perfusion: a prospective study with >5 years of follow-up.

Purpose: To assess the time-dependence of radiation therapy (RT)-induced reductions in regional lung perfusion, as measured by single photon emission computed tomography (SPECT) lung perfusion scans.

Methods And Materials: Between 1991 and 1999, 79 patients had SPECT lung perfusion scans before and serially after RT. Changes in regional perfusion were correlated with regional dose using 3D planning tools and image fusion (PLUNC-Plan UNC).