PubMed Health⌕ Search

Biomedical subjects

Thomas C Gerber

Publications and source records attributed to Thomas C Gerber.

15 recordsLinked to original sources
PubMed2006

Eisler and his pocket.

PURPOSE: To identify the original description of the anatomical structure referred to as "Eisler's pocket." DESIGN: Historical review. METHODS: Review of published reports. RESULTS: Contemporary reports cite a 1963 textbook by an American author as the source of the term "Eisler's pocket." The original description by Eisler appears in a multivolume manual of ophthalmology published in Germany in 1930. CONCLUSION: Paul Eisler was a skilled anatomist who contributed to the extensive body of scholarly work originating in Germany in the early 20th century.

Anatomy↗
PubMed2006

Computed tomographic angiography of the coronary arteries: techniques and applications.

Computed tomographic coronary angiography (CT-CA) is a direct but minimally invasive method of visualizing coronary arteries. Multidetector-row computed tomography (MDCT) is currently the CT modality most commonly used for coronary artery imaging. MDCT has been successfully used to detect stenoses in coronary arteries and coronary artery bypass grafts and to assess congenital coronary anomalies. Patients should not undergo CT-CA with MDCT if they have an irregular heart rhythm, a heart rate greater than 70 beats/min, and contraindications to pharmacologic agents for heart rate control, or if they have severe coronary artery disease or are likely to require revascularization.

Coronary Angiography↗
PubMed2005

Techniques and parameters for estimating radiation exposure and dose in cardiac computed tomography.

With increasing clinical use of cardiac CT imaging it is important that all health care providers referring for or administering such examinations are familiar with the concepts and values of radiation dosimetry in CT as well as with the basic principles of radiation protection. There are important technical differences pertinent to radiation dose between the CT scanner types that are currently being used for imaging of the heart and coronary arteries. As a result of these differences, the radiation dose typically is higher when a cardiac examination is performed with multidetector-row CT (MDCT) than when it is performed with electron beam CT. Several techniques have been described to reduce radiation dose of MDCT imaging by varying the X-ray tube current during a CT examination. The volume computed tomographic dose index (CTDIvol), the dose length product (DLP), and the effective dose (E) are the most useful parameters to describe and compare radiation doses received from cardiac CT examinations. When comparing radiation doses between scanning protocols and scanner types, the degree of image noise must be considered. Diagnostic, rather than aesthetic, quality of images should be the most important factor guiding the development of scanning protocols for cardiac CT imaging. Cardiac CT examinations should be ordered only by qualified health care providers, and the ordering clinicians should be aware of their responsibility of weighing risks of the radiation exposure against the expected benefits.

Heart↗
PubMed2005

Effect of acquisition technique on radiation dose and image quality in multidetector row computed tomography coronary angiography with submillimeter collimation.

RATIONALE AND OBJECTIVES: We sought to examine effects of tube voltage and current on radiation dose and image quality for minimally invasive coronary angiography with a 16-slice multidetector row computed tomography (MDCT) scanner. MATERIALS AND METHODS: We scanned the phantom used in the American College of Radiology Computed Tomography Accreditation Program at tube voltages of 80 and 120 kVp at 550, 650, and 750 mAseff, with and without a reduction in radiation dose by electrocardiographically (ECG) controlled tube current modulation (ECG pulsing). RESULTS: Without ECG pulsing, the effective dose was 3 to 13 mSv. On average, a 50% increase in tube voltage led to increased radiation dose (215%), contrast-to-noise ratio (150%), and decreased image noise (-48%). On average, a 17% increase in mAseff led to increased radiation dose (17%) and contrast-to-noise ratio (4%) and decreased image noise (-9%). Dose reduction by ECG pulsing (simulated heart rate, 70 beats per minute) was 28%. With ECG pulsing, noise in images reconstructed during ventricular systole was double that in images reconstructed during ventricular diastole. CONCLUSIONS: These quantitative findings about the relationships among scan acquisition parameters, radiation dose, and image quality have practical implications for using ECG pulsing to reduce radiation doses in MDCT coronary angiography.

Algorithms↗
PubMed2004

Imaging of congenital coronary anomalies with multislice computed tomography.

OBJECTIVE: To describe a single-center experience of using retrospectively gated multislice computed tomographic (MSCT) coronary angiography for imaging congenital coronary anomalies. PATIENTS AND METHODS: We retrospectively reviewed the clinical information and imaging studies for 9 patients diagnosed as having congenital coronary anomalies on invasive, selective coronary angiography between February 2001 and October 2003 at the Mayo Clinic in Jacksonville, Fla. Two experienced observers classified by consensus the origin and proximal course of the abnormal coronary arteries as seen on MSCT. RESULTS: In 1 patient, MSCT showed a normal but extremely anterior origin of the right coronary artery from the right aortic sinus of Valsalva. In the other 8 patients, the origin and course of 4 anomalous right coronary arteries, 2 anomalous left circumflex coronary arteries, and 2 single coronary arteries were recognized easily on MSCT. CONCLUSION: Similar to electron beam computed tomography and magnetic resonance imaging, widely available MSCT can characterize the proximal course of congenitally abnormal coronary arteries and thus aid in clinical decision making for patients with such anomalies.

Adult↗
PubMed2003

Clinical safety of magnetic resonance imaging early after coronary artery stent placement.

OBJECTIVES: Our aim was to examine the rate of adverse cardiac events in patients undergoing magnetic resonance imaging (MRI) <8 weeks after coronary stent placement. BACKGROUND: The risk of coronary stent thrombosis from dislodgement due to MRI early after stent placement is not well defined. Manufacturers recommend postponing MRI studies until eight weeks after coronary stent placement. METHODS: We analyzed the Mayo Clinic Rochester Percutaneous Coronary Intervention Database and examined records of 111 patients who underwent MRI <8 weeks after coronary stent placement treated with aspirin and a thienopyridine. Occurrence of death, myocardial infarction (MI), and repeat revascularization within 30 days of MRI were recorded. RESULTS: Magnetic resonance imaging (1.5 tesla) was performed within a median of 18 days (range, 0 to 54 days) after coronary stent placement. Four noncardiac deaths occurred, and three patients had repeat revascularization procedures. Stent thrombosis did not occur (95% confidence interval, 0% to 3.3%). CONCLUSIONS: Magnetic resonance imaging <8 weeks after coronary stent placement appears to be safe, and the risk of cardiac death or MI due to stent thrombosis is low. Postponing MRI does not appear to be necessary.

Aged↗
PubMed2003

[Noninvasive computed tomographic coronary angiography as a complement to coronary calcium quantification in symptomatic patients].

BACKGROUND: Invasive, selective coronary angiography remains the "gold standard" of direct visualization of epicardial coronary arteries. Technical advances in recent years and improvements in image quality in both electron beam computed tomography (EBT) and multislice spiral/helical computed tomography (MSCT) brought along an increasing interest in the potential clinical role of noninvasive computed tomographic coronary angiography (CTCA). POTENTIAL AND LIMITATIONS: Measurement of coronary calcification permits quantitative estimation of overall coronary plaque burden and thereby allows assessment of cardiovascular risk and likelihood of the presence of a significant stenosis. However, the precise site and degree of stenoses cannot be measured. Contrast-enhanced CTCA lumenography permits visualization of epicardial coronary artery stenoses with a sensitivity and specificity of about 90%. Noncalcified plaques may also be detected in individual cases, but very few data are available on this aspect of CTCA. Image artifacts due to rapid motion, especially in the distal segments of the right and circumflex coronary arteries, may preclude reliable assessment of 20-30% of these segments. Also, in-stent restenoses and distal bypass anastomoses will, in the foreseeable future, remain difficult to confidently diagnose by CTCA. Combined assessment of calcified plaque burden and CTCA may enhance diagnostic accuracy especially in patients with low or moderate calcium scores. In the presence of heavy calcifications, stenoses may be masked. INDICATIONS: Noninvasive CT-based evaluation of coronary arteries seems useful in patients with a low to intermediate pretest likelihood for significant coronary artery disease (CAD). This holds for several ACC/AHA class II indications described for invasive, selective coronary angiography and for few class I indications. Further prospective studies are required to establish the clinical value of combined assessment of coronary calcium quantification and CTCA.

Calcinosis↗
PubMed2003

Physics and dosimetry in computed tomography.

CT data acquisition and image reconstruction techniques are closely related to image quality and patient radiation dose. There is little question that technological developments currently underway will change the nature of both, and result in improved quality and diagnostic value of cardiovascular CT images while hopefully minimizing radiation dose to the patient.

Algorithms↗
PubMed2003

Evaluation of reconstruction windows for multislice computed tomography in quantification of coronary calcium.

RATIONALE AND OBJECTIVES: To search for an optimum reconstruction window in retrospectively gated multislice computed tomography (MSCT) for quantification of coronary calcium. MATERIALS AND METHODS: Coronary calcium quantified was examined as Agatston and volume scores by two experienced observers at 10 time points across the R-R interval of the electrocardiogram in 42 patients. A combination of statistical approaches was used to evaluate the distributions of minimum and maximum scores and of interobserver variability for both scoring methods across the cardiac cycle. RESULTS: Based on the combination of evaluation approaches, 60% to 70% of the R-R interval appeared to be the optimum time point for obtaining maximum calcium scores with minimum interobserver variability. The optimum time point was more clearly defined for the Agatston score than for the volume score. CONCLUSION: A reconstruction window beginning at 60% to 70% of the R-R interval seems to be most advantageous for retrospective gating of MSCT studies performed to quantify coronary calcium.

Adult↗
PubMed2002

Current results and new developments of coronary angiography with use of contrast-enhanced computed tomography of the heart.

Electron beam computed tomography (EBCT) is the reference standard for x-ray-based tomographic imaging of the heart because of its high temporal resolution, but it is available in only a few centers. Quantification of coronary calcium is the most widely recognized use of EBCT for cardiac imaging. This technique requires no contrast media and provides an accurate assessment of overall plaque burden in the coronary tree; however, it does not directly identify or localize coronary stenoses. Multislice spiral (helical) CT (MSCT) is a new technology that provides images of the beating heart in diagnostic quality under many circumstances and may facilitate the broader application of cardiac and coronary CT. Currently, for imaging of the heart, much more experience exists with EBCT than with MSCT. Contrast-enhanced CT coronary angiography (CTCA) can be done with EBCT or MSCT to obtain images of the major branches of the coronary tree and to define luminal narrowing. Studies at experienced centers performed with small numbers of patients show that sensitivity, specificity, and negative predictive value are good with CTCA in the assessment of obstructive coronary artery disease, but CTCA remains an investigational technique for these applications. Computed tomographic coronary angiography can be clinically useful for assessing coronary artery bypass graft patency and congenital coronary abnormalities.

Contrast Media↗
PubMedDate not supplied

Image quality in a standardized algorithm for minimally invasive coronary angiography with multislice spiral computed tomography.

PURPOSE: To report our experience with a standardized approach to pharmacologic heart rate control and image postprocessing for computed tomographic coronary angiography (CTCA) with multislice computed tomography (MSCT). METHOD: Two experienced observers used transaxial tomograms and maximum-intensity projections to classify coronary segments (12 per patient, 135 consecutive patients) for degree of stenosis. One factor affecting image quality was identified for each segment that could not be assessed. RESULTS: Nine patients (7%) were excluded for technical reasons. Of 1,512 segments from 126 patients, 1,086 (72%) were assessable (8.6 per patient). Of 300 segments from 25 patients who also had selective coronary angiography, CTCA was able to assess 211 (70%) and detected significant disease in 27 (82% sensitivity, 96% specificity, 73% positive predictive value, and 97% negative predictive value). Vessel caliber, heart rate, and Agatston score were associated with inability to assess 426 coronary segments (28%). CONCLUSION: Heart rate and Agatston score are important predictors of the ability to assess proximal and midcoronary segments by CTCA with MSCT.

Adult↗