Quantitation of shunting at the atrial level using rapid acquisition computed tomography with comparison with cardiac catheterization.

Contrast-enhanced rapid acquisition computed tomography was employed to quantitate intracardiac shunts in two adult patients. Contrast medium was injected through a median antecubital vein and data were accumulated using the R wave-triggered flow mode. Time-density curves from a region of interest were generated by a gamma variate fit method and areas under the curves were calculated. Comparisons of calculated left to right shunts (Cases 1 and 2) with results of computed tomography and right to left shunt (Case 2) with cardiac catheterization data resulted in close agreement. This is the first report of quantitation of intracardiac shunts at the atrial level in humans by rapid acquisition computed tomography.

The effect of Butterworth and Metz reconstruction filters on volume and ejection fraction calculations with 99Tcm gated myocardial SPECT.

This study was carried out to measure the differences produced by change of reconstruction filter in calculations of left-ventricular end-diastolic volumes, end-systolic volumes, stroke-volumes and left-ventricular ejection-fractions from (99)Tc(m) Sestamibi (Bristol-Myers Squibb) gated myocardial perfusion SPECT studies. 30 patients had gated SPECT myocardial perfusion imaging at rest. The acquired projections were separately filtered with two filters, a low-pass filter (Butterworth) and an edge-enhancement filter (Metz). Each study was then further processed to determine left-ventricular end-diastolic volume, end-systolic volume, stroke volume and ejection fraction, and to assess defect size. The results for each patient with the two filters were compared. Calculated end-diastolic volumes, end-systolic volumes and left-ventricular ejection fractions, for each filter, were well correlated. Stroke volumes showed worse correlation. The differences between left-ventricular ejection-fractions, end-diastolic volumes and end-systolic volumes were statistically significant. There was no significant difference in stroke volumes. Ejection fractions were inversely correlated with defect size, but change in ejection fraction due to filter was not. End-diastolic and end-systolic volumes were correlated with defect size, but change in volumes due to filter was not. Thus the results for changes produced by choice of filter are not dependent on defect size. Using different reconstruction pre-filters in gated myocardial perfusion SPECT significantly changes the results of calculations of physiological parameters. Each centre should be consistent in the use of filters as this may affect the clinical consequences of the result.

In vivo validation of a novel semi-automated method for border detection in intravascular ultrasound images.

The aim of this work was to evaluate a new semi-automated intravascular ultrasound (IVUS) border detection method. The method was used to identify the lumen and the external elastic membrane or the borders of stents in 80 IVUS images, randomly selected from 10 consecutive human coronary arteries. These semi-automated results were compared with observations of two experts. Several indices in each case were obtained in order fully to evaluate the method. The time required for identification of the borders was also recorded. The interobserver variability of the method ranged from 1.21% to 5.61%, the correlation coefficient from 0.98 to 0.99, the slope was close to unity (0.94-1.03), the y intercept close to zero and the Williams index value was close to unity (range 0.67-0.91). The time (mean+/-SD) required for the method to identify the borders of the different vessel layers for the whole IVUS sequence was 5.2+/-0.2 min. The results demonstrate that the method is reliable and capable of identifying rapidly and accurately the different vessel layers depicted in IVUS images.

Radiographic features and prognosis in bronchioloalveolar carcinoma; a local experience.

The prognosis of 20 patients with histologically proven bronchioloalveolar carcinoma was assessed in the light of their radiographic features and symptoms at presentation. Radiographically, half the patients were classified as having focal disease of which 60% were focal consolidation. Other focal presentations were, a mass lesion in three cases and a single 3 cm nodule in one case. Those with diffuse disease presented with either coarse widespread nodules or diffuse alveolar opacification with or without a focal area of consolidation. All patients were symptomatic at presentation but the severity of the symptoms bore no relation to the radiological findings. Seven cases with focal disease underwent thoracotomy, five of which had evidence of hilar and mediastinal lymph node involvement. They included a case presenting with a nodule, two with a mass and four with focal consolidation. The survival following surgery was generally better with those with a mass or nodule but one case with focal consolidation remains alive 10.5 years following surgery compared with the longest survivor of 4.5 years with a mass. Both these relatively long-term survivors had no histological evidence of hilar or mediastinal lymph node involvement compared with the other surgical cases. The median survival in cases without surgery was one month. The prognosis was better in patients with focal disease where surgery was performed and we feel that a local area of consolidation should be treated as focal disease and surgical resection considered for these patients.

Assessment of coronary stent by intravascular ultrasound.

The use of intravascular ultrasound to assess the adequacy of the deployment of an intracoronary stent is described. Although angiographically a good result was suggested, intravascular ultrasound showed this to be misleading.

Use of thermal imaging to monitor crural thrombolysis.

Intra-arterial thrombolysis is increasingly being used as the treatment of choice in selected cases of critical limb ischaemia. At present angiography is the established method of monitoring the progress of thrombolysis. We report a case in which thermal imaging was used in conjunction with angiography to monitor the effects of thrombolysis.

Does peripheral angioplasty compromise limb blood flow?

Isotope limb blood flow studies were carried out using balloon, laser and Kensey catheter techniques to assess the outcome of peripheral angioplasty. Limb blood flow and Doppler ankle-brachial pressure measurements were obtained before angioplasty and at 6 months after angioplasty in a total of 101 angioplastied limbs: A fall in limb blood flow at 6 months was seen in 17% of the angioplastied limbs with no significant difference in the figures for the different types of angioplasty. Limb blood flow was also measured in 53 contralateral untreated limbs, approximately half of the patient group having both legs angioplastied. 25% of untreated limbs showed a fall in limb blood flow. Significantly more of the untreated limbs showed a fall in limb blood flow at 6 months where the contralateral, treated limb did not improve as a result of the angioplasty compared with those patients where the angioplastied leg improved. These results suggest that a lack of improvement in blood flow in the angioplastied limb may not result from failure of the angioplasty but may be the result of some factor, or combination of factors, which adversely affects both the angioplastied and the untreated leg in some patients.

Limb blood flow measurement in technically successful balloon angioplasty.

An isotope limb blood flow technique was used to assess the outcome of technically successful balloon angioplasty. Measurements were made on a total of 120 limbs, before angioplasty and at least once after angioplasty at 3 weeks, 3 months, 6 months, 12 months and 2-5 years. 67% of treated limbs showed a significant improvement in limb blood flow at 3 weeks. At 12 months following angioplasty 43% of limbs still showed an improvement in blood flow compared with the measurement made before angioplasty. However, a number of these limbs showed a significant fall in limb blood flow between 3 weeks and 12 months even though the 3 week and the 12 month flow figures were still greater than those before angioplasty. The degree of initial improvement in blood flow seen at 3 weeks persisted at 12 months after angioplasty without significant fall in only 30% of limbs. In 33% of limbs where the balloon angioplasty was technically successful there was no improvement in blood flow at 3 weeks. 80% of these limbs had further significant untreated disease angiographically, compared with 43% of limbs where there was an increase in limb blood flow.

Technical note: femoral angiography using the reverse shuffle technique.

We report our findings using the "reverse shuffle" technique of stepping table femoral angiography. This technique represents a simple modification of the conventional stepping table sequence entailing a reverse table movement allowing acquisition of early and late films in the distal positions. It was developed in order to minimize the number of runs required in each examination. In a retrospective study 52/53 (98%) of angiograms using the reverse shuffle technique required only a single run compared with 30/51 (58%) using the conventional technique. We believe that the reverse shuffle should be used where possible when stepping table angiography is performed. Furthermore, the incorporation of a reverse table movement may also be advantageous in angiography using automated digital subtraction angiography (DSA) stepping systems.

Fast magnetic resonance angiography using turbo-FLASH sequences in advanced aortoiliac disease.

A prospective study using contrast enhanced turbo-FLASH (Fast Low-Angle Shot) magnetic resonance (MR) angiography was performed to assess the arterial anatomy in patients who had advanced atherosclerotic aortoiliac disease. This new imaging sequence was employed in 17 patients and the results were compared with conventional abdominal aortography. MR angiography accurately detected all aortic occlusions (3/3), their sites and their extent. All nine iliac occlusions were correctly identified (sensitivity 100%, specificity of 90%). The sensitivity was 100% for stenosis of 50% or greater in the abdominal aorta, and the iliac and common femoral arteries. The degree of stenosis was overgraded in 20 of 51 lesions (39.2%). Mild stenosis was overgraded as moderate stenosis in 10 and as severe stenosis in three. Moderate stenosis was overgraded as severe stenosis in four. None of the mild or moderate stenoses resulted in areas of signal voids suggestive of occlusions. Three severe stenoses were seen as areas of signal voids (two iliac, one femoral). In the eight patients who had in total 10 aneurysmal dilatations of the aorta or the iliac arteries, MR angiography was superior in demonstrating the true extent of the aneurysms. We conclude that turbo-FLASH MR angiography has the potential to be a useful non-invasive imaging technique for patients with advanced aortoiliac disease.

The use of soft and flexible guidewires in the treatment of chronic total coronary occlusions by activated guidewire angioplasty.

Activated guidewire angioplasty (AGA) is a new technique which has been designed to assist in angioplasty of total occlusions. The purpose of this study was to determine the safety and efficacy of using flexible relatively soft guidewires (floppy wires) in conjunction with this technique and also to determine the predictors of lesion crossing and final success by this technique in patients with chronic total coronary occlusions. 73 patients with 73 chronic total coronary occlusions in whom coronary angioplasty using conventional techniques had failed were treated with AGA using floppy guidewires. The success of crossing these lesions was 65.7% (48/73) resulting in a final angioplasty success of 56.1% (41/73). Angioplasty success was reduced compared with crossing success in seven arteries in which complications occurred during balloon angioplasty. Multiple stepwise logistic regression analysis identified the location of the occlusion (right coronary artery, p = 0.005) as independent predictor of crossing success of this technique and the male gender (p = 0.03), the duration of occlusion (p = 0.05), the lesion length (p = 0.01) and the location of the occlusion (right coronary artery, p = 0.02) as independent predictors of final procedural success of the method.

The use of gated perfusion scanning in the assessment of left ventricular volume.

A total of 34 patients underwent both gated SPECT perfusion imaging and echocardiography, with each test blinded to the other. Wall motion analysis, calculation of ejection fraction and ventricular volume were obtained by each technique. A close correlation was observed between the ejection fractions calculated by each method (r=0.79). There was a less close relationship between the left ventricular volumes calculated by each method (r=0.61) this is probably due to the errors which result from geometric assumptions for each technique. Wall motion analysis revealed a good level of agreement between each method with no significant discrepancies between the techniques.

A comparison of methods for estimating left ventricular volumes from radionuclide ventriculography.

An accurate reproducible measurement of left ventricular volume is important in the evaluation of cardiac disease. Four methods of left ventricular volume measurement by radionuclide ventriculography have been compared and their reproducibility assessed in a patient group. The methods studied were a geometric method, a method based on count data alone and two methods which require a blood sample and an estimate of ventricular depth. The accuracy of absolute volumes is difficult to determine due to the lack of a 'gold standard'. The method using count data alone was found to give reproducible results. Volumes can be calculated quickly and easily from data acquired in a standard radionuclide ventriculogram. End systolic volumes calculated using this method clearly separated normal and abnormal patient groups.

Determinants of left ventricular ejection fraction by ultrafast computed tomography.

Twenty-seven patients had left ventricular ejection fraction (LVEF) measured by catheterization, single-plane angiography, and ultrafast computed tomography (cine CT). Twelve patients (mean age sixty-two years) had LVEF measured by use of the cine CT long-axis view LAV), and 15 patients (mean age fifty-eight years) had LVEF measured by use of the cine CT transaxial view (TAV). Cine CT LVEF was measured by means of two methods of edge detection (M1 and M2). A significant correlation was found between single-plane angiography and cine CT LAV LVEF (M1, r = .96; M2, r = .93). A lesser correlation was found for catheterization vs TAV cine CT LVEF (M1, r = .77; M2, r = .81). There was no significant difference between the two methods of edge detection for determining LVEF (M1 vs M2: LAV, r = .98; TAV, r = .94); however, there was significant variability in cavity volumes. Therefore, the LAV is superior to the TAV for measurement of LVEF by cine CT; however, different methods of edge detection, though affecting volumes, may not affect LVEF.

Comparison of left ventricular ejection fraction by cine computed tomography and single plane right anterior oblique ventriculography.

Cine Computed Tomography (CCT) is a minimally invasive technique which offers high temporal (50 msec scan time) and spatial (2 line pairs) resolution. Left ventricular ejection fraction (LVEF) has been determined by this technique in dogs and normal subjects but no comparison has been made with contrast left ventriculography by cardiac catheterization. Ten patients, 9 male and 1 female, mean age 61 (range 46-70) had LVEF determined by both single plane RAO left ventriculography and CCT. Patients were studied in the fasting state, on different days without change in medication. LVEF by CCT was determined in the long axis, a new view which has been developed for CCT to be comparable to the RAO view of contrast left ventriculography by catheterization. This view is obtained by positioning the patient head first into the scanner, supine, with a counterclockwise table slew (20 degrees) without table tilt. Contrast is introduced via a median antecubital vein, and injected in a prolonged bolus of 7-13 seconds dependent on arm to heart circulation time. Scans are performed in the cine mode (17 frames/sec) timed during maximal opacification of the right and left ventricles. Four or six contiguous levels are imaged as required to slice the entire left ventricular cavity. End-systolic and end-diastolic frames are identified. Left ventricular cavity areas are determined by computerized planimetry after the Hounsfield level number is set at half the difference between the contrast in the cavity and the myocardium and setting the window width at one giving a black and white image. Left ventricular end-diastolic volume (LVEDV) and end-systolic volume (LVESV) per slice are summated to obtain LVEDV and LVESV from which LVEF is desired.(ABSTRACT TRUNCATED AT 250 WORDS)

Rapid acquisition computed tomographic assessment of left ventricular regional wall motion using a new long axis view.

A long axis view to demonstrate left ventricular regional wall motion was devised for the ultrafast CT scanner. The patients are positioned supine, head first, into the scanner. The scan table is slewed 20 degrees counter-clockwise in the horizontal plane without tilt. A bolus of contrast is injected via a median antecubital vein. Contiguous level R wave triggered cine studies are obtained during peak passage of contrast through the heart to image the entire left ventricular cavity. Fourteen patients had left ventricular wall motion compared by long axis CT and RAO 30 degrees single plane ventriculography at catheterization. In all cases, regional wall motion in comparable segments by both methods was in agreement. It is concluded that the ultrafast CT long axis view permits diagnosis of left ventricular regional wall motion abnormalities. This view images the apex and sections the interventricular septum and lateral free wall horizontally. Unlike conventional CT views, it is comparable to the RAO left ventriculogram.

Fast rotating atherectomy catheter tip inhibits platelet aggregation and ATP release: a study using platelet-rich plasma.

The interaction of atherectomy devices with the arterial wall is the focus of many studies, but their effect on the surrounding blood is largely unknown. This is a detailed investigation on the effects of a rotational atherectomy device with a fast rotating tip on platelet structure and function. Platelet-rich plasma (PRP) was obtained from six volunteers, divided into 5 mL samples, and subjected to the atherectomy tip rotating at 20, 40, or 80 thousand rpm for 30 or 60 seconds. Platelet aggregation to collagen or adenosine diphosphate (ADP) was obtained in all samples by means of a dual-chamber optical aggregometer. The fast rotating catheter tip caused marked inhibition of platelet aggregation to both collagen and ADP. The maximum extent of aggregation was reduced from 85% +/-2.8 in control to 46% +/-4.8 with collagen (p<0.01) and from 86.1% +/-6.9 to 25.1% +/-4.3 with ADP (p<0.01). The rate of aggregation (measured at 4 minutes) dropped from 81.3% +/-2.7 to 40% +/-4.5 and from 73.9% +/-8.5 to 12.5% +/-2.6 (p<0.005) with collagen and ADP, respectively. These effects were related to rotating speed and duration of exposure. ATP release in response to collagen fell from 2.63 +/-0.13 nMol in control to 0.7 +/-0.1 nMol, p<0.001 after exposure to the rotating tip. There was no significant change in platelet count, nor was there formation of platelet aggregates (platelet aggregate ratio remained unchanged) to account for these phenomena. Furthermore, transmission electron microscopy showed no significant platelet disruption or release of granules, and little signs of activation were seen even after addition of collagen. This is the first study to demonstrate that exposure to a fast rotating catheter tip inhibits in vitro platelet aggregation and ATP release. There were no apparent loss of integrity of platelet structure, release of granules, or formation of platelet aggregates. This phenomenon and its clinical implication justify further investigation.

Experimental and clinical percutaneous angioscopy experience with dynamic angioplasty.

The authors have used ultrathin angioscopes with high optical resolution to assess the effects of dynamic angioplasty in vitro and in vivo. Experimentally, angioscopy was used to study the effects of the 5F "Kensey" catheter in "normal" porcine coronary arteries (NPCA) and postmortem human coronary arteries (PMHCA). In NPCA, the catheter keeps a coaxial position. Intimal flaps (IFs) were seen in 21/23 NPCAs. They occurred with all cam rotation speeds and were usually single and small (less than 25% of lumen). Perforations in patent arteries were rare (1/23). However, when the catheter was forced against the wall by passing through a narrowing of 5F diameter (made by a band ligature), perforations were more common at higher cam speeds. The epicardium remained intact in two thirds of perforations. Angioscopy visualized perforations in only 10% of cases (1/10), the common sign being that of large and multiple intimal flaps, which were often obstructive (5/10). In PMHCAs, angioscopy was more sensitive than angiography in detecting atheromatous lesions. The authors were able to give a better assessment of the effect of dynamic angioplasty on treated lesions, including the demonstration of intimal flaps that were not visible on angiography. In vivo, they have performed percutaneous angioscopy before and after dynamic angioplasty using 8 French Kensey catheters. Angioscopy revealed features that were not shown angiographically.

Experimental analysis of sapphire contact probes for Nd-YAG laser angioplasty.

Laser angioplasty may offer percutaneous recanalization of occluded vessels where conventional guidewire and balloon techniques fail. Metal laser thermal angioplasty probes may, however, cause excessive thermal damage due to high tip temperatures (greater than 400.C). Therefore, contact probes made from artificial sapphire crystal designed for general laser surgery are currently being evaluated for use in laser angioplasty with continuous wave Nd-YAG energy. The sapphire modifies the laser energy in various ways, and this paper examines the physical characteristics of five types of rounded sapphire probe (SMTR, MTR, MTRL, OS, LT) and how these properties are affected by clinical usage. The laser beam profile emitted by these probes demonstrates a focal spot 1-2 mm in front of the tip. However, the forward transmission of Nd-YAG energy through the sapphires varied (SMTR, 85%; MTR, 83%; MTRL, 75%; OS, 54%; LT, 69%). Probe heating occurs owing to energy absorption within the sapphire. The surface temperature of the sapphires was measured in air by infrared thermography and the hottest region within the probes localized by an isothermographic technique. At energy settings used clinically (20 J, 10 watts for 2 s) the SMTR, MTR, and MTRL probes exhibited higher temperature rises (94-112.C) than the OS and LT probes (30.C), and heating was localized to the front surface of the former probes. Peak sapphire temperatures remained lower than those of metal probes even at higher energies. After clinical use, the MTR probe demonstrated reduced transmission, beam defocusing, and increased heating, due to surface pitting. Thus, recanalization with sapphire probes occurs by a combination of photothermal and contact thermal effects that are localized to the probe tip and may reduce the degree of thermal injury associated with metal probes. Understanding these basic properties is important to the application and development of contact probes for laser recanalization.

Demonstration of mitral valve function by cine computed tomography using a new long axis view.

Comparison was made between contrast enhanced cine computed tomography (Cine/CT) and echocardiography in the imaging of the mitral valve in 14 patients. The mitral valve was seen in all 14 patients by Cine/CT using a new long axis view. There was agreement with echocardiography in 12 patients. Abnormalities in mitral valve movement were detected by Cine/CT. Left atrial size and contraction was measured by Cine/CT with a difference in left atrial ejection fraction observed between 13 patients with no evidence of mitral disease and 3 patients with mitral disease.