The purpose of the present study was to evaluate the robustness of a method of automated border detection in cardiac magnetic resonance (MR) imaging. Thirty-seven short-axis spin-echo cardiac images were acquired from three medical centers, each with its own image-acquisition protocol. Endo- and epicardial borders and areas were derived from these images with a graph-searching-based method of edge detection. Computer results were compared with observer-traced borders. The method accurately defined myocardial borders in 36 of 37 images (97%), with excellent agreement between computer- and observer-derived endocardial and epicardial areas (correlation coefficients, .94-.99). The algorithm worked equally well for data from all three centers, despite differences in image-acquisition protocols, MR systems, and field strengths. These data suggest that a method of computer-assisted edge detection based on graph-searching principles yields endocardial and epicardial areas that correlate well with those derived by an independent observer.

Adult↗

PubMedDate not supplied

Automated myocardial edge detection on MR images: accuracy in consecutive subjects.

The authors previously demonstrated the feasibility of graph-searching-based automated edge detection in cardiac magnetic resonance (MR) imaging. To further assess the clinical utility of this method, unselected images from 11 consecutive subjects undergoing clinically indicated (except for one healthy volunteer) short-axis spin-echo MR imaging were analyzed. A total of 142 images from the 11 subjects, encompassing the left ventricle from apex to outflow tract, were analyzed. The computer algorithm correctly identified complete endocardial and epicardial contours in 121 of 142 images (85%). Correlations between observer-traced and computer-derived epicardial areas for all images were good (r = .71 for epicardium, r = .83 for endocardium); they improved for a subset of higher-quality images (r = .82 for epicardium, r = .92 for endocardium). The authors conclude that the current data further support the usefulness of computer digital image processing in geometric analysis of cardiac MR image data.

Adolescent↗

PubMedDate not supplied

High-resolution computed tomography and diffuse lung disease.

Diffuse lung diseases are often difficult to characterize on chest radiographs. It has been a challenge for the radiologist to obtain useful diagnostic information from these studies and then communicate that information to the clinician. Robert Heitzman recognized the utility of understanding lung diseases in terms of their effect on the structures of the secondary lobule. Unfortunately, he needed inflated lung specimens to reliably visualize the small structures within the secondary lobule. Such specimens are no longer needed. High-resolution computed tomography (HRCT) scans of the lung provide an excellent representation of the secondary lobule. In this monograph, we have attempted to explain the normal anatomy of the secondary lobule, the patterns of abnormality, the technique for performing HRCT, and an approach to diffuse lung disease. In the second half of the article we have classified the more common diffuse lung diseases according to the dominant pathologic change: high versus low attenuation.

Diagnosis, Differential↗

PubMedDate not supplied

Detection of the source of recurrent Staphylococcus aureus bacteremia by ultrafast computerized tomography.

A patient with spina bifida secondary to an Arnold-Chiari deformity experienced seven episodes of sustained bacteremia due to Staphylococcus aureus over 2 years. Despite an extensive diagnostic evaluation the source of the recurrent bacteremia remained obscure. The patient's mother eventually recalled that a procedure for replacement of a ventriculoatrial shunt performed 16 years earlier had been complicated by retention of a shunt fragment in the bloodstream. Standard radiographic techniques failed to identify an intravascular foreign body; however, ultrafast computerized tomography of the heart demonstrated a density in the right atrium. Atriotomy was performed and a plastic catheter fragment was excised. Bacteremia has not recurred during a follow-up period of 24 months. Patients with recurrent unexplained bacteremia should be evaluated carefully for the presence of occult intravascular catheter fragments that may be retained after surgical procedures or intravascular instrumentation. Ultrafast computed tomographic scanning of the heart is a useful technique for detecting intracardiac catheter fragments.

Adolescent↗

PubMedDate not supplied

Coronary artery calcification as an indicator of preclinical coronary artery disease.

Explore the source record for details and available documents.

Biomarkers↗

PubMedDate not supplied

Ventilatory pattern, intrapleural pressure, and cardiac output.

Continuous positive-pressure ventilation may decrease cardiac output. However, a few reports have separated the effects of positive and end-expiratory pressure (PEEP) from those of mechanical ventilation. Ten surgical patients requiring mechanical ventilatory support had catheters inserted for measurement of right atrial pressure (RAP), pulmonary artery occlusion pressure (PAOP), intrapleural, radial artery, airway, and atrial filling pressures, and cardiac output. All patients breathed spontaneously between mechanical breaths delivered every 30 seconds by intermittent mandatory ventilation (IMV). Measurements were made with 0, 5, and 10 cm H2O PEEP, and during intermittent positive-pressure ventilation (IPPV) with 12 breaths/min without PEEP. Airway pressure (Paw), intrapleural pressure, RAP, and PAOP were increased by PEEP and IPPV. Intrapleural pressure increased most during IPPV (p less than 0.001). Atrial filling pressures and cardiac output were unaffected by PEEP but decreased during IPPV (p less than 0.001). Patients receiving IMV maintained negative intrapleural pressure, atrial filling pressure, cardiac output and, therefore, O2 delivery, regardless of PEEP level. The authors conclude that patients requiring mechanical respiratory support, with or without PEEP, may maintain better cardiopulmonary function when allowed some spontaneous ventilatory activity.

Blood Gas Analysis↗

PubMedDate not supplied

Electron beam computed tomographic imaging of aortic aneurysms and dissections.

Electron Beam Computed Tomography (EBCT), like conventional CT has the capability to acquire high resolution images of the aorta. The millisecond image acquisition time characteristic of EBCT makes it an ideal modality to evaluate patients with suspected aneurysms or dissections of the aorta. Unlike conventional CT, electron beam technology produces images with excellent resolution, minimal respiratory artifact, and superior vascular enhancement. Compared with alternative modalities, EBCT probably represents a superior tool in the workup of aortic pathology. Whether in the acute or chronic setting, the reliability, speed, ease, and reproducibility of EBCT makes it truly superior in the diagnosis and follow-up of aortic aneurysms and dissections.

Aortic Dissection↗