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Biomedical subjects

Lawrence M Boxt

Publications and source records attributed to Lawrence M Boxt.

12 recordsLinked to original sources
PubMed2006

An unusual combination of myocardial bridging and coronary artery aneurysm identified on 64-detector coronary angiography.

Coronary artery aneurysm is an uncommon finding. It is defined as a dilated coronary artery which exceeds the diameter of the normal adjacent vessel by 1.5-2 times. Although theorized mechanisms include atherosclerotic coronary artery disease (CAD) and iatrogenic causes such as the use of percutaneous coronary interventions (PCI), the natural history and prognosis of this disease remain obscure. We describe a case of a 75 year old man who was found to have a long segmental myocardial bridge immediately followed by a 5 mm inner diameter aneurysm in the left anterior descending artery (LAD) detected on 64-detector cardiac computed tomography (64-CT). The post myocardial bridge aneurysmal dilatation in this case is unique, and has not been previously described. With the advent of 64-CT, more incidental cardiac anomalies and irregularities are likely to be found. In the end, the question as to the clinical significance of these findings and their treatment remains controversial. We report this novel case and review the literature for recommendations on treatment and management of patients with coronary aneurysms.

Aged↗
PubMed2005

CT of valvular heart disease.

Although the incidence of valvular heart disease is significantly less than before the introduction of antibiotic therapy, chronic mitral and aortic valve disease continues to be found in the adult population. CT examination reveals characteristic chamber volume and myocardial mass changes expected in patients with valvular obstruction and regurgitation. Furthermore, CT provides sensitive visualization of annular and valve leaflet calcification, both of which are important findings for determining the presence of disease and estimating the significance of valvular dysfunction identified on examination. Although CT is by no means the first diagnostic modality to be employed in management of patients with valvular heart disease, it does reveal the sequelae of such disease, and may, in fact, provide insight into the significance of clinical or echocardiographic findings. Improved temporal resolution will increase the accuracy of CT diagnosis, and further expand its use for diagnosing and managing patients with cardiac disease in general, and valvular heart disease, in particular.

Calcinosis↗
PubMed2005

CT anatomy of the heart.

Contrast-enhanced ECG-gated multidetector CT provides high contrast and spatial resolution for imaging the thoracic organs. High photon flux, very rapid gantry rotation, and very sensitive photon detectors optimize the scanner for cardiac imaging. ECG-gating (and pharmacological intervention, i.e., beta-blockade), have increased temporal resolution. The structure of the heart is revealed in a manner convenient for all radiologists. The atria and ventricles display their characteristic morphology. Antero-posterior and left-to-right relationships are apparent. Viewing through space, or reconstructing in orthogonal planes enforces the supero-inferior relationships as well. Appreciation of normal structure is the foundation for detecting the abnormal.

Contrast Media↗
PubMed2004

Magnetic resonance and computed tomographic evaluation of congenital heart disease.

Magnetic resonance imaging (MRI) and contrast-enhanced computed tomography (CT) provide noninvasive visualization of morphologic changes in pediatric and adult patients with congenital heart disease, as well as the functional changes caused by the underlying morphologic abnormalities. Clinical experience with MRI is richer than that with fast CT, but CT appears to provide accurate and high-quality imagery for diagnosis. The two modalities may be complementary. That is, intracardiac anatomy is so well depicted by MRI, and CT provides exquisite images of the great vessels. Furthermore, in adult patients, MR and CT are helpful in demonstrating and quantitating physiologic changes superimposed by acquired cardiovascular disease on the underlying congenital malformations. Using MRI, spin echo acquisitions provide the image data for evaluation of morphologic changes, and gradient reversal techniques add functional and flow data to complement morphologic changes. Contrast-enhanced electrocardiographic (ECG)-gated multidetector and electron beam CT examination provide morphologic information and may be used as a data set for off-line functional quantitation.

Adult↗
PubMed2004

How to approach cardiac diagnosis from the chest radiograph.

Direct visualization of pathologic changes in the heart has significantly influenced the diagnostic accuracy and management of patients with cardiovascular disease. This article presents an approach to plain film examination of the heart based on basic principles of radiologic evaluation. It emphasizes the relationship between the radiologic appearance of a structure and the technique used to obtain that image, and the relationship between the observation of a structural abnormality and the anatomic relationships that allow that observation to be made. This approach is simple, organized in a logical manner, and when applied rigorously results in not only accurate and insightful differential diagnosis, but also a deep understanding of cardiovascular disease processes.

Diagnosis, Differential↗
PubMed2004

Calcifications of the heart.

Cardiac calcification usually represents the result of a pathologic process. Some forms of calcification represent chronic change in an ageing population, and must be differentiated from pathologic calcification. Still other forms of calcification are associated with ageing and chronic degeneration, but also reflect ongoing pathologic processes. Recognition of cardiac calcification may be an early sign or only sign of a pathologic process. Characterization of the calcification in terms of its distribution and appearance is a helpful means for determining which structures are calcified, differentiating pathologic from nonpathologic processes. This article provides an overview of the types of calcifications of the heart, pathogenesis, and utility of the various imaging modalities for their detection.

Calcinosis↗
PubMed2003

Computed tomography for assessment of cardiac chambers, valves, myocardium and pericardium.

The focus to date of MDCT has been primarily on CT applications for evaluating the coronary arteries, notably the measurement of coronary artery calcification, plaque characterization, and atherosclerotic lumen stenosis. This is because of the limited temporal resolution of CT, and the recent rapid improvements in MRI for cardiac applications. However, if the temporal resolution of MDCT can be improved, there will be a compelling argument for undertaking further CT validation studies. Feasibility of CT has already been established by EBT for general cardiac diagnosis. Modifications for MDCT include improved software methods for post processing ECG-gated scan data or higher speed CT hardware for faster image acquisition, both of which are being developed at this time. EBT is also evolving and continuously being refined so that the new generation of scanners have exposure times of 50 msec or less. There are many considerations in comparing the pros and cons of competing cardiac imaging modalities. Published diagnostic validations studies, convenience, procedure time, the comfort level (of patients and physicians), availability, and cost are all critical. The level of acceptance and the accuracy with which specific patient management questions can be appropriately answered are crucial issues in determining which diagnostic procedure to perform. However, the jury is still out regarding the ultimate role of CT in the diagnosis of heart disease; certainly the great potential of cardiac CT has not yet been fully realized.

Cardiomyopathies↗
PubMed2003

MR imaging of congenital heart disease.

MR examination of patients with congenital heart disease is a useful means of explicitly demonstrating chamber morphology and, in particular, morphologic changes caused by physiologic changes brought on by particular defects. Use of MR techniques allows characterization of chamber morphology for determination of cardiac connections and great artery relationships. The high-contrast resolution of spin echo acquisition provides important morphologic detail. Cine gradient echo techniques complement spin echo acquisition by providing functional and flow information. Although MR examination complements echocardiographic investigation in pediatric and adult patients, is may be useful for replacing angiocardiography, shortening examination time, and decreasing morbidity in diagnostic workups of these patients.

Heart Defects, Congenital↗
PubMed2003

MR imaging of arrhythmogenic right ventricular dysplasia.

MR imaging is helpful in the management of patients in whom the diagnosis of ARVD or RVOTT is suspected. Careful attention to cardiac rate control will minimize or eliminate ventricular extrasystolic beats during examination, which will improve image quality and confidence in diagnosis. Use of thin-section cine gradient echo acquisition provides a means of identifying regional wall motion abnormalities, characteristic of the regional dysfunction in these diseases. Furthermore, application of spin echo or double inversion recovery imaging may provide visualization of abnormally thin or fat-infiltrated regions of right ventricular free wall myocardium, providing additional diagnostic criteria for the diagnosis of these diseases.

Arrhythmogenic Right Ventricular Dysplasia↗
PubMed2003

MR Imaging of arrhythmogenic right ventricular cardiomyopathy: morphologic findings and interobserver reliability.

BACKGROUND: Magnetic resonance (MR) imaging is frequently used to diagnose arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D). However, the reliability of various MR imaging features for diagnosing ARVC/D is unknown. The purpose of this study was to determine which morphologic MR imaging features have the greatest interobserver reliability for diagnosing ARVC/D. METHODS: Forty-five sets of films of cardiac MR images were sent to 8 radiologists and 5 cardiologists with experience in this field. There were 7 cases of definite ARVC/D as defined by the Task Force criteria. Six cases were controls. The remaining 32 cases had MR imaging because of clinical suspicion of ARVC/D. Readers evaluated the images for the presence of (a) right ventricle (RV) enlargement, (b) RV abnormal morphology, (c) left ventricle enlargement, (d) presence of high T(1) signal (fat) in the myocardium, and (e) location of high T(1) signal (fat) on a Likert scale with formatted responses. RESULTS: Readers indicated that the Task Force ARVC/D cases had significantly more (chi(2) = 119.93, d.f. = 10, p < 0.0001) RV chamber size enlargement (58%) than either the suspected ARVC/D (12%) or no ARVC/D (14%) cases. When readers reported the RV chamber size as enlarged they were significantly more likely to report the case as ARVC/D present (chi(2)(= )33.98, d.f. = 1, p < 0.0001). When readers reported the morphology as abnormal they were more likely to diagnose the case as ARVC/D present (chi(2) = 78.4, d.f. = 1, p < 0.0001), and the Task Force ARVC/D (47%) cases received significantly more abnormal reports than either suspected ARVC/D (20%) or non-ARVC/D (15%) cases. There was no significant difference between patient groups in the reported presence of high signal intensity (fat) in the RV (chi(2) = 0.9, d.f. = 2, p > 0.05). CONCLUSIONS: Reviewers found that the size and shape of abnormalities in the RV are key MR imaging discriminates of ARVD. Subsequent protocol development and multicenter trials need to address these parameters. Essential steps in improving accuracy and reducing variability include a standardized acquisition protocol and standardized analysis with dynamic cine review of regional RV function and quantification of RV and left ventricle volumes.

Adult↗