Biomedical subjects
Publications and source records attributed to D Bone.
Five species of polychaetes (Spionidae) were found associated to Thalassia testudinum meadows in Parque Nacional Morrocoy, Venezuela. We included a guide for their identification and present range extensions for the Venezuelan coasts and Southern Caribbean Sea. The species are: Dipolydora socialis, Prionospio (Minuspio) cirrifera, P. (Prionospio) fallax, P. (P.) steenstrupi, and Spio pettiboneae.
AIMS: This prospective study assesses the (1) feasibility of quantifying ultrasound myocardial perfusion studies based on the densitometric analysis of digital data and the (2) comparison of pulse inversion, second harmonic and harmonic power Doppler modalities with SPECT. METHODS AND RESULTS: Twenty-three patients with suspected ischaemic heart disease had i.v. injections of Tc-Sestamibi and Optison during a dipyridamole stress test for echocardiography in pulse inversion, second harmonic and harmonic power Doppler mode. Analysis was (a) visual by scoring and (b) quantitative by densitometry of digital data for background subtracted myocardial opacification (a.u.) and normalized contrast effect (%). In the nine control patients, myocardial opacification at stress was greater (P< or =0.002) than in the pathologic group (5. +/- 3.3 vs 2.6 +/- 2.5 a.u. in pulse inversion, 5.4 +/- 2.1 vs 2.4 +/- 1.8 in second harmonic and 7.1 +/- 3.7 vs 4.9 +/- 3.7 a.u. in harmonic power Doppler). In the pathologic group, normalized contrast effect decreased significantly during stress (23.7 +/- 18.8 to 11.3 +/- 10.8%, P<0.003) only in pulse inversion. Kappa values for patient based diagnostic agreement with SPECT were 0.75 by pulse inversion, 0.62 by second harmonic and 0.52 by harmonic power Doppler for quantitative analysis, and 0.51, 0.37 and 0.35 respectively, for visual assessment. CONCLUSION: Myocardial contrast echocardiography should be analysed using densitometry of digital data. The new technique pulse inversion demonstrates best agreement with SPECT data.
An iterative Bayesian reconstruction algorithm for limited view angle tomography, or ectomography, based on the three-dimensional total variation (TV) norm has been developed. The TV norm has been described in the literature as a method for reducing noise in two-dimensional images while preserving edges, without introducing ringing or edge artefacts. It has also been proposed as a 2D regularization function in Bayesian reconstruction, implemented in an expectation maximization algorithm (TV-EM). The TV-EM was developed for 2D single photon emission computed tomography imaging, and the algorithm is capable of smoothing noise while maintaining edges without introducing artefacts. The TV norm was extended from 2D to 3D and incorporated into an ordered subsets expectation maximization algorithm for limited view angle geometry. The algorithm, called TV3D-EM, was evaluated using a modelled point spread function and digital phantoms. Reconstructed images were compared with those reconstructed with the 2D filtered backprojection algorithm currently used in ectomography. Results show a substantial reduction in artefacts related to the limited view angle geometry, and noise levels were also improved. Perhaps most important, depth resolution was improved by at least 45%. In conclusion, the proposed algorithm has been shown to improve the perceived image quality.
A total of 40 species of syllids (Polychaeta: Syllidae) inhabiting Thalassia testudinum beds in Morrocoy National Park, Venezuela, belonging to 13 genera, are reported; 36 species are new for Venezuela: Branchiosyllis exilis, B. oculata, Eusyllis lamelligera, Exogone arenosa, E. breviantennata, E. naidinoides, E. naidina, E. parahomoseta mediterranea, Grubeosyllis clavata, G. heterocirra, Odontosyllis detecta, O. enopla, O. gibba, Opisthosyllis brunnea, Plakosyllis brevipes, Sphaerosyllis bilobata, S. glandulata, S. magnidentata, S. piriferopsis, S. riseri, S. longilamina, S. taylori, Syllis alosae, Syllis riojai, n. comb., S. beneliahui, S. broomensis, S. cornuta, S. corallicola, S. garciai, S. hyalina, S. lutea, S. mexicana, S. prolifera, S. sardai and Xenosyllis scabra.
The intravenous application of an ultrasound contrast agent induces enhanced display of blood in all its pathways. Within cardiology, this principle is mainly utilized for signal enhancement of color Doppler and spectral Doppler in order to improve quantification of congenital and acquired valvular lesions and also for improved endocardial delineation during stress tests and in the evaluation of LV function. The new domaine of myocardial perfusion imaging by contrast echocardiography, however, needed profound technical developments before realization of the clinical potential could even be conceived. These are based on the complex reactions of microbubbbles in the acoustic field in order to allow the sensitive and bubble specific display of intramyocardial contrast effects. The presently available acquisition techniques, second harmonic imaging and harmonic power Doppler, demonstrate significant improvements if compared to traditional fundamental 2-d echocardiography; however, they are still subjected to important limitations. There are many anatomical, physiological, and technical reasons for insufficient display of intramyocardial microbubbles, the most important one being attenuation. It is hoped that the most recently developed imaging modality, pulse inversion technique, allows the necessary diagnostic accuracy and reproducibility in myocardial perfusion imaging.
Pleurodesis of malignant pleural effusion provides for a substantially better quality of life compared to onging exudation with the need for repeated evacuation of fluid. Successful pleurodesis leads to permanent cessation of fluid production as a result of the formation of fibrous adhesion between the lung and costal pleura which in theory, however, might restrict lung mobility. In patients with poor lung function, or with need for bilateral pleurodesis, the apprehension of further impairment of lung function often arises. The aim of this study was to evaluate the effects of pleurodesis on lung function. Therefore 10 patients with malignant pleurisy with very limited tumour were investigated. They were without radiological signs of tumour infiltration in the lung parenchyma, without visible tumour growth in the pleural space during thoracoscopy and had undergone a successful one-sided pleurodesis. Respiratory function tests were performed at different times, 1-102 months after pleurodesis. The assessment consisted of: static and dynamic spirometry, exercise testing with blood gas determination and radiospirometry. Spirometric values were slightly low, but in general within the reference limits. Blood gas determination showed no signs of alveolar hypoventilation. Radiospirometry showed a slight attenuation of activity in the treated lung but similar turnover of gas of the treated vs. the untreated side. The study showed that pleurodesis in malignant pleurisy has only minor impact on respiratory function.
A study was conducted to determine the time dependency of myocardial perfusion improvement after coronary artery bypass graft (CABG) surgery. Seventeen 3-vessel diseased patients (16 male, 1 female) scheduled for CABG surgery from a cardiac surgical and intensive-care unit were examined. Ten of the 17 patients returned for examination after 1 year. A titrated adenosine infusion was used to expose reversible ischemia. Tc99m-sestamibi was injected at rest and at maximum adenosine infusion rate, and isotope distribution was determined using ectomographic myocardial scintigraphy. Visually scored percent isotope uptake defect size and percent uptake reduction were assessed. It was found that resting isotope uptake defects were unchanged 1 h after surgery, increased in severity after 1 week, and after 1 year were 24% less than the preoperative scores (p < 0.01) and 55% less than after 1 week (p < 0.001). It was found that adenosine infusion induced a 57% increase in average defect score preoperatively (p < 0.001) but no increase postoperatively. No differences were seen between regions supplied by arterial or venous grafts. Isotope uptake defects increased between 1 h and 1 week after CABG surgery, and after 1 year the scores were less than those recorded preoperatively and after 1 week. Adenosine-induced reversible isotope uptake changes seen preoperatively were eliminated postoperatively in all vessel regions.
(-)-Norepinephrine is the predominant neurotransmitter of the sympathetic innervation of the heart. Racemic norepinephrine was labelled with carbon-11 and injected i.v. into Cynomolgus monkeys. Five minutes after injection there was a more than tenfold higher radioactivity in the heart than in adjacent tissue. Pretreatment with the norepinephrine reuptake inhibitor desipramine reduced the uptake by more than 80%. The high specific uptake of racemic [11C]norepinephrine indicates that enantiomerically pure (-)-[11C]norepinephrine has promising potential for detailed mapping of the sympathetic innervation of the human myocardium.
1. Local skeletal muscle blood flow was monitored using the microdialysis ethanol technique and 133Xe clearance during intermittent isometric contractions (5 s on/10 s off) of the thigh at 0-60% of the maximal voluntary isometric contraction force. 2. A linear increase in blood flow over a 25-fold range was detected using both 133Xe clearance and the microdialysis ethanol technique. 3. The median correlation coefficient between percentage maximal voluntary isometric contraction force and the ethanol outflow/inflow ratio, a marker of blood flow, was r = -0.98 (-0.94 to -0.99) (median and range, n = 6). The corresponding correlation coefficient for 133Xe clearance was r = 0.97 (0.92-0.98), the correlation coefficient between the ethanol outflow/inflow ratio and 133Xe clearance being r = -0.92 (-0.89 to -0.94). 4. Dialysate glucose concentration, although affected by blood flow, was not always significantly correlated with blood flow changes (r = 0.70; 0.51-0.95). 5. It may be concluded that the ethanol technique provides a valid measure of changes in local skeletal muscle blood flow. The data furthermore show that a linear increase in thigh skeletal muscle blood flow exists during the studied protocol of intermittent isometric contractions.
Eighteen patients with stable exertional angina pectoris were investigated by thallium-201 (201Tl) exercise and redistribution single photon emission computed tomography (SPECT) after coronary angiography. Eight of the patients had a previous myocardial infarct. Six patients had single-, eight double- and four triple-vessel disease. An exercise SPECT was acquired 10 min after the administration of isotope, injected 1-2 min before the termination of a symptom-limited exercise test. A redistribution SPECT was recorded 3 h later. 201Tl activity per pixel was compared between the exercise and redistribution SPECT in relative and absolute terms. For each patient there was a good correlation between activity per pixel in the redistribution SPECT and the corresponding pixels in the exercise SPECT (mean correlation coefficient 0.86 +/- 0.08), irrespective of the extent of coronary artery disease or presence of a previous infarction in the pixel region. Relative wash-out correlated to the degree of coronary artery stenosis (r = 0.48), but did not differ between infarcted and non-infarcted myocardial regions. A similar relationship was documented for pixels with visual 'refill' in the redistribution SPECT. This implies that most of the information in the redistribution SPECT was present already in the exercise SPECT. Thus, qualitative information of a similar kind is obtained from images acquired immediately after exercise and after 3-4 h of redistribution.
Perfusion abnormalities and infarct size evaluated by thallium-201 SPECT after late thrombolysis followed by anti-thrombotic treatment in acute myocardial infarction were studied in 111 patients. Patients were prospectively randomized to a treatment group (n = 54) receiving streptokinase initiated 12-49 h after onset of symptoms, followed by heparin for at least 5 days and warfarin and dipyridamole for at least 3 months, or to a control group (n = 57) treated routinely without any of these drugs. Thallium-201 scintigraphy was performed within 3 months of follow-up in 40 (74%) of the patients in the treatment group and 46 (81%) in the control group. During a symptom-limited bicycle test the isotope was injected at peak exercise. SPECT was acquired 10 min later (exercise SPECT) and after 3 h (redistribution SPECT). A computerized quantitative analysis was performed. Defects were defined as regions with activity below 40% of the maximum. In the exercise SPECT defects were significantly smaller in the treatment group than among control patients (9 +/- 12% vs 15 +/- 15% of the left ventricle; P < 0.05). The difference was more apparent in patients with Q-wave than in those with non-Q-wave infarctions and the entire difference was accounted for by patients without a previous history of infarct or angina pectoris. There was no statistically significant difference in defect size in the redistribution SPECT (5 +/- 10% vs 9 +/- 11%, ns).(ABSTRACT TRUNCATED AT 250 WORDS)
Primary neoplasms of the heart are rare and difficult to diagnose prior to surgery, even with modern imaging techniques. Often, the tumors are diagnosed only at autopsy. Angiosarcoma is the most common malignant neoplasm. This disease is most commonly found in middle-aged men, and the tumor is most often located in the right atrium. It commonly causes blood flow abnormalities, extensively infiltrates cardiac structures, and may extend through the heart wall to involve adjacent structures. Metastatic spread at the time of diagnosis is common, and surgical mortality is high. We present a case of primary angiosarcoma involving the right ventricle of the heart. This tumor developed 6 months after the patient had undergone coronary artery bypass surgery. The patient was initially thought to have a massive thrombus within the right ventricle but at surgery was found to have a malignant neoplasm invading the myocardium. Subsequently, he was found to have pulmonary metastases. A debulking procedure was performed, and the patient was started on chemotherapy. Rather prompt improvement occurred after the debulking procedure, but subsequent studies have indicated progression of the pulmonary metastases despite ongoing chemotherapy.
Polar presentations of selective coronary angiography and myocardial 201Tl SPECT were compared in 141 patients with multiple vessel disease, 80 with 3-vessel disease, 34 with 2-vessel disease and 27 post-bypass patients. Perfusion defects were present in 125/141 patients (89%) and were located within the area supplied by 194/359 stenotic arteries (54%) and 9 non-stenotic arteries. The type and extent of disease was correctly indicated by 201Tl SPECT in 16/80 patients (20%) with 3-vessel disease, 5/34 patients (15%) with 2-vessel disease and 8/27 post-bypass patients (30%). Perfusion defects indicated the artery with the most severe lesion in 107/125 patients (86%). False negative isotope studies were present in 15 patients (11%).
A tomographic method using a limited-view angle has been evaluated. In studies using a gamma camera and a rotating 30-degree slant-hole (RSH) collimator, 64 projection images were registered. A special filtered backprojection technique was used for reconstruction of section images parallel to the collimator face. Resolution within such sections was 0.6 cm, 3 cm from the collimator face and 1.3 cm at 18 cm. Depth resolution was 2.2 cm at 3 cm and 5.1 cm at 18 cm. Spacing between section images was regular and geometric distortion negligible. Short-axis section images of a myocardium in vivo were qualitatively comparable or better than those obtained with single-photon emission computed tomography. Degradation in the posterior wall due to attenuation and scatter was less. Section images of the facial bones and a hip joint further demonstrated the tomographic capability of the method.
Tomographic imaging of the myocardium was performed using a gamma camera and a 30-degree rotating slant-hole collimator to register 64 projections from a restricted-view angle. Section images were reconstructed with a two-dimensional filtered backprojection technique. Performance in terms of resolution, effects of misalignment, and three-dimensional activity distribution was evaluated in phantom studies. In a limited clinical study, ten consecutive patients were imaged both with single-photon emission computed tomography (SPECT) and the method described. In the new method, the camera was orientated in the 30 degrees left anterior oblique position with 15 degrees cranial tilt. Due to the short distance from the myocardium to the camera, resolution within reconstructed section images was high, the noise level was comparatively low, and the mean activity level in the posterior wall was significantly higher (p less than 0.005) than in SPECT.
Polar presentations of coronary angiograms and myocardial 201Tl SPECT were compared in 44 patients without significant coronary artery disease (less than 50% stenosis at angiography). Regions of reduced isotope activity (defects) were present in 18 patients (41%). Nine of these had angiographic and/or clinical evidence of non-coronary heart disease, such as documented or suspected myocardial infarction, dilated cardiomyopathy or other myocardial diseases. Such defects could be caused by impaired small vessel blood flow, abnormalities in cell membrane transport or relative differences in left ventricular wall thickness. In 9 patients defects were probably due to attenuation artifacts. Defects in patients with heart diseases were significantly larger than in those without obvious disease. The information content in coronary angiography and 201Tl SPECT overlap but are not congruent. Coronary angiography describes morphology of large coronary vessels, whereas 201Tl SPECT contains information of large and small vessel perfusion as well as membrane transport of 201Tl ions.
Polar presentations of selective coronary angiography and myocardial 201T1 SPECT were compared in 49 patients with single vessel disease. Twenty-six lesions were located in LAD, 8 in LCX and 15 in RCA. Perfusion defects were found within the supply area of 44 stenotic and 20 non-stenotic arteries. 201T1 SPECT detected coronary disease in 45 patients (92%) and the obstructed artery in 44 (90%). Single vessel disease was correctly indicated in 28 patients (57%) where the perfusion defects did not extend significantly outside the area supplied by the stenotic artery. Extensive perfusion defects could be explained by 'collateral steal', myocardial disease, LV aneurysm or spasm in 9 patients (18%). The absence of perfusion defect related to the stenotic artery could be explained by a moderate degree of stenosis or well developed collateral vessels in 5 patients (10%). Proximal LAD lesions resulted in larger perfusion defects than distal.
Tomographic 201-Tl scintigrams (SPECT) were compared with conventional planar images (PLAN) in 100 consecutive patients with ischaemic heart disease (IHD). Agreement was obtained in 78/100 and disagreement in 7/100. In 15 patients the results were equivocal. The sensitivity of PLAN and SPECT was studied in 35 patients with IHD and angina pectoris who were also examined with coronary angiography. SPECT had a sensitivity of 88 per cent compared with 84 per cent for PLAN. SPECT was better in matching perfusion defects to coronary stenoses in this small patient group.