Detection of active colonic hemorrhage with use of helical CT: findings in a swine model.

Purpose: To evaluate the feasibility of helical computed tomography (CT) as an imaging modality for depicting active colonic hemorrhage in a swine model.

Materials And Methods: Controlled extravasation of contrast material-enhanced blood (CEB) from 140 to 180 HU and at varying rates (0.3-1.

Noninvasive determination of myocardial blood flow, oxygen consumption and efficiency in normal humans by carbon-11 acetate positron emission tomography imaging.

The aims of this study were: (1) to measure noninvasively and near simultaneously myocardial blood flow, oxygen consumption, and contractile function and (2) to analyze myocardial energy expenditure and efficiency at rest and during dobutamine stress in normal humans. Dynamic and gated carbon-11 acetate positron emission tomography (PET) imaging was performed in 11 normal subjects. The initial uptake of (11)C-acetate was measured to estimate myocardial blood flow.

Three-dimensional correction for spillover and recovery of myocardial PET images.

Unlabelled: PET permits the quantification of myocardial blood flow, but is hampered by the limited spatial resolution of PET images.

Methods: We evaluated two methods for the correction of resolution effects in PET perfusion 13NH3-ammonia images. In one model, the spillover and recovery coefficients are estimated in the kinetic modeling analysis.

Quantification of myocardial blood flow using dynamic nitrogen-13-ammonia PET studies and factor analysis of dynamic structures.

Unlabelled: In this study, factor analysis of dynamic structures (FADS) was used to extract the "pure" blood-pool time-activity curves (TACs) and to generate parametric myocardial blood flow (MBF) images (pixel unit: ml/min/g).

Methods: Ten dynamic 13N-ammonia dog PET studies (three baseline, five hyperemia and two occlusion) were included. Three factors (TACs) and their corresponding factor images (the right ventricular and left ventricular blood pools and myocardial activities) were extracted from each study.

Parameter estimation of cardiac geometry by ECG-gated PET imaging: validation using magnetic resonance imaging and echocardiography.

Unlabelled: The purpose of this study was to apply and validate a previously developed model-based image analysis technique which derives estimates of regional myocardial wall thickness and the left ventricular radius directly from gated cardiac PET images.

Methods: In 11 normal volunteers, gated myocardial 18F-deoxyglucose (FDG) images with 16 equal gates spanning the entire cardiac cycle were acquired for 20 min. To improve count statistics and thus image quality, 3 and 5 of 16 gates were summed to obtain systolic and diastolic images.