American journal of cardiac imaging最新文献

The purpose of the study was to compare four intravascular ultrasound (IVUS) machines in vitro for their image representation of coronary arterial walls. There has been considerable variability among reported studies on the accuracy of morphometric measurements of coronary arteries by IVUS. This variability may be caused in part by the difference in the IVUS system used. A total of 24 formalin-fixed coronary arteries were imaged in saline at 37 degrees with four different IVUS systems. The images were interpreted independently and compared with histology. Each system had benefits and limitations: System 1 overestimated the lumen area and had difficulty in identifying the media; System 2 underestimated the media area, but had a lower positive bias for lumen area; System 3 overestimated the lumen area but more clearly identified tissue characteristics such as internal elastic membrane and the echolucent media zone which improved the likelihood of observing a three-layer appearance; and System 4 showed less distinct separation of the arterial components and had poor correlations with histology for media measurements. The ability to make accurate morphometric measurements from IVUS images depends on the clarity of the separation of plaque and media. Among the four systems studied, there is significant variability in the appearance of the ultrasound images and the accuracy of morphometric measurements. These system differences should be considered when comparing IVUS studies performed by different groups.

Advancing The Standard (ATS) Medical (ATS Medical Inc., Minneapolis, MN) is a new mechanical bileaflet valve, composed of pyrolitic carbon. The aim of this study was to define in a blinded manner the Doppler echocardiographic characteristics of normally functioning ATS Medical prostheses with respect to their size. Forty consecutive patients (29 men, mean age 58 +/- 13 years), clinically stable, and without evidence of valve dysfunction, were studied from 1993 to 1995. Doppler echocardiography was performed at least 3 months after valve replacement with ATS Medical valves (5 n degrees 21, 8 n degrees 23, 12 n degrees 25, 10 n degrees 27, 5 n degrees 29). Maximum and mean transprosthetic pressure gradients were calculated by the simplified Bernoulli equation. Functional valve surface area was assessed by the continuity equation using the external diameter of the prostheses to calculate the subaortic surface area. The Doppler velocity index was obtained by the ratio of subaortic and transaortic velocities and the performance index was calculated dividing the effective orifice area by the actual orifice area. For the most commonly used aortic valve (25 mm), the maximum pressure gradient was 17 +/- 8 mmHg, the mean gradient 11 +/- 4 mmHg, the functional surface area 2.2 +/- 0.4 cm2, the Doppler velocity index 0.44 +/- 0.07, and the performance index 0.68 +/- 0.11. This study provides the normal range for Doppler hemodynamic characteristics of the various sizes of the ATS valve.

Unlabelled: Straight back syndrome (SBS) is usually diagnosed by physical and chest radiographic findings. Radiographic computed tomographic (CT) findings are very useful for the diagnosis and the evaluation of its severity. The purpose is to evaluate the relationship between chest X-ray film and CT findings.

Subjects: We evaluated 26 patients (SBS group) and 11 normal subjects (control group). SBS group consisted of 15 patients without structural heart disease (group I) and 11 patients with other heart disease (group II).

Methods: (1) On the chest X-ray film, antero-posterior diameter (APD) of the thorax, transthoracic diameter (TTD), and APD/TTD ratio were measured. (2) On the CT image, three parameters were calculated; APD of the left atrium (LA diameter), APD/transverse diameter ratio of the heart (flattening ratio) and left side shift ratio of the heart (shifting ratio). (3) CT parameters were compared with APD/TTD ratio in patients and control group.

Results: (1) APD/TTD ratio was smaller in group I and II than control group (30.0 +/- 5.4, 30.5 +/- 4.0 v 44.6 +/- 2.7%, p < .001). (2) LA diameter was smaller in group I and II than control group (23.2 +/- 4.1, 26.0 +/- 8.6 v 30.0 +/- 6.5 mm, p < .01). Flattening ratio was also smaller in group I and II than control group (59.2 +/- 9.4, 61.8 +/- 8.6 v 75.4 +/- 13.2%, p < .01). Shifting ratio was greater in group I and II than control group (10.9 +/- 5.0, 11.9 +/- 4.5 v 8.4 +/- 4.0%, p < .01). (3) APD/TTD ratio correlated with LA diameter (r = .39, p < .05) and flattening ratio (r = .53, p < .001). APD/TTD ratio did not correlate with shifting ratio (r = -.27, NS).

Conclusions: APD/TTD ratio correlated with LA diameter and flattening ratio rather than shifting ratio. LA diameter and flattening ratio on the CT image were more useful for evaluating the severity.

Unlabelled: There are conflicting reports on the relationship between left atrial dimension (LAD) determined by echo-cardiography and the incidence of atrial fibrillation (AF) recurrence after electrical cardioversion (EC). We hypothesized that left atrial volume (LAV) by echocardiography might better differentiate patients who will have recurrence of AF after EC.

Methods: Forty-one patients having EC for AF were prospectively studied by echocardiography. LAD was measured by American Society of Echocardiography guidelines as the anterior-posterior dimension in the parasternal view. LAV was measured by Simpson's method using an off-line analysis system and reported as the average of values from the apical four-chamber and two-chamber views.

Results: (Data are mean +/- SEM): Patient follow-up was 15 +/- 10 months. No cutoff value of LAV predicted AF recurrence, but all three patients with LAD greater than 65 mm had AF recurrence. Compared with patients maintaining normal sinus rhythm (NSR) (N = 18), the AF group (N = 23) had a lower percentage of antiarrhythmic drug use, especially type IA agents (p < .02). Patients who stayed in NSR tended to have shorter AF duration before EC (16 +/- 15 v 63 +/- 122 weeks, p = .08) but did not differ in age (53 +/- 27 v 58 +/- 23 years), LAD (51.1 +/- 7.7 v 54.2 +/- 9.4 mm) or LAV (85.1 +/- 24.3 v 95.1 +/- 33.3 mL).

Conclusions: (1) LAV by echocardiography does not improve identification of patients at risk for recurrence of AF after EC, (2) patients with LAD up to 65 mm may maintain NSR after EC, (3) LAD greater than 65 mm is associated with AF recurrence, and (4) use of antiarrhythmic drugs and the duration of AF before EC may be better predictors of maintenance of NSR than echocardiographic measures of left atrial parameters.

Thrombosis of upper extremity veins and superior vena cava (SVC) can occur in patients with indwelling central venous catheters. Contrary to earlier reports, pulmonary embolism (PE) can result from these thrombi, especially when they are attached to catheters (sleeve thrombi) in contrast to venous wall (mural thrombi). Removal of catheters may be required when sepsis occurs or to reduce risk of sepsis when lines have been left in for several days. We describe two patients with thrombi in SVC related to central venous catheters in whom transesophageal echocardiography (TEE) was performed during catheter removal to monitor for thrombus dislodgement. TEE may have a role in showing thrombus dislodgement and embolization during removal of venous catheters complicated by SVC thrombi. Direct visualization of thrombus dislodgement may aid in early diagnosis of PE because signs and symptoms of PE are often missed or mistaken for underlying cardiopulmonary disease. TEE may also play a role in implementing appropriate treatment in patients with PE who show right ventricular strain.

Six relevant computer-implemented reference systems for three-dimensional quantitative assessment of left ventricular wall motion abnormalities were compared with visual wall motion analysis of two-dimensional images. Endocardial borders were traced in three apical echocardiographic views at end-diastole and end-systole in 10 patients with myocardial infarction and 5 healthy subjects, and three-dimensional reconstruction of endocardial surfaces was performed. End-diastolic and end-systolic surfaces were aligned in a common axis system depending on the reference system, and systolic wall motion was assessed at 1,024 points on the endocardial surface. The localization of abnormal wall motion was displayed in bull's-eye maps, and the area was determined as a percentage of total endocardial area. For each reference system, the segmental concordance between three-dimensional computerized and visual assessment was determined. The best agreement between computerized and visual analysis was obtained with a reference system based on wall motion towards the major ventricular axis, whereas the poorest result was obtained using the center of left ventricular cavity as reference. Correlation between the estimated area of wall motion abnormality and visually determined wall motion score index was best using the aligned center of mitral valve plane as reference (r = .92).

Different intravascular ultrasound (IVUS) systems vary in their image presentation. The purpose of this study was to compare four IVUS systems in vitro to determine the accuracy of tissue characterization of atherosclerotic plaque compared with histology. Ninety-eight plaque segments from 23 formalin-fixed human iliac arteries were imaged in saline at room temperature with four different IVUS systems. To assess the accuracy of IVUS in describing plaque, three types of analysis were performed: (1) the ability to identify the presence and extent of lumen or plaque boundary; (2) sensitivity, specificity, and interobserver variability of IVUS in qualitatively identifying plaque components compared with histology; and (3) quantification of calcification. The synthetic aperture device had a lower sensitivity in identifying lumen and plaque boundaries (87%, 38% respectively) compared with other machines (96%-100%, 95%-100%). All three mechanically rotating systems had fair to good sensitivities for identifying calcification (57%-73%) or lipid filled areas (50%-83%). The sensitivity of discriminating fibrous tissue from fatty areas was low (39%-52%). The synthetic aperture system had a significantly lower sensitivity for identifying all three tissue types (4%-21%). There was significant interobserver variability (kappa value = 0.47-0.68) as well as machine to machine variability (kappa value = 0.52) for tissue characterization. Calcified areas were underestimated by System 1 (p < .05) and System 4 (p < .01) because of weaker echo reflections or poor image quality. There are significant differences in image representation among these four IVUS systems in the diagnosis of tissue components of complex atherosclerotic plaque. These variabilities should be considered when interpreting studies performed with different machines.

Objectives: Electrocardiographic (ECG) trigger records obtained during cardiac ultrafast computed tomography (UFCT) scanning were analyzed to estimate the variability in heart rate and ECG trigger interval to develop a protocol that would allow the development of better ECG triggering software.

Methods: One-hundred-eighteen patients underwent cardiac UFCT imaging for diagnostic purposes. All subjects were divided into three groups according to the heart rate and ECG trigger condition. Thirty slices were obtained in the high-resolution volume mode for each patient.

Results: A decrease in heart rate and ECG trigger interval was found during image acquisition of the first four slices in all three groups. The nadir of the heart rate occurred during acquisition of the 4th slice, 5.3, 3.5, and 5.6 beats per minute less than the initial heart rate in groups 1, 2, and 3 respectively, with a 6.9%, 2.8%, and 5.0% shorter ECG trigger interval (p < .001, p = .08, p < .05, respectively). From the 4th to the 30th slices, heart rate and ECG trigger interval progressively increased, but less variability was found in the last 20 slices in all three groups.

Conclusions: Significant variation in heart rate and ECG trigger interval was seen during 30-level cardiac UFCT imaging, especially during image acquisition of the first four slices (approximately 1-6 seconds after breatholding). This can result in scanning during the suboptimal phase of the cardiac cycle by the current UFCT triggering software. A delay in the initiation of scanning to approximately 6 to 10 seconds after breatholding would result in imaging during a time when the heart rate is relatively stable, and a smaller variability in ECG trigger interval occurs. Recalculation of the required delay before each heart beat may improve the precision of ECG triggering.

There are increasing data to support the use of the electron beam computed tomography (EBCT) scanner for early detection of coronary artery disease (CAD). A negative scan essentially rules out significant disease. How many EBCT 3 mm contiguous slices are needed to cover the coronary circulation? To answer this question, 104 consecutive patients referred for EBCT scan for evaluation of coronary artery calcium (CAC) were asked to participate. The sensitivity and negative predictive value (NPV) of calcium scores for the first 10 slices and first 20 slices, the second 20 slices, and the total scan were recorded. Scores greater than one were regarded as positive. The number of levels required to cover the entire heart was also recorded. Fifty-nine patients (56.7%) had a positive calcium score for the total scan. Of these, 53 were positive for the first 10 slices (sensitivity = 89.8%, NPV 88.2%), and 57 were positive for the first 20 slices (sensitivity = 96.6%, NPV 95.7%). The median number of levels required to cover the entire heart was 34, and 97.2% of cases were covered in 40 or fewer levels. The use of 20 slices for purposes of detecting CAC is a reasonable choice for the C-100 scanners, because this would be accomplished in a breath hold. When the first slice starts at the base of the right pulmonary artery, all patients with CAC were identified. The C-150 scanner with the ability to scan on each heartbeat would increase sensitivity and NPV by acquiring 30 to 40 slices in a single breath hold.