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At least 1,225 records · Page 68Linked to original sources
PubMed1987

Abnormalities of esophageal transit in patients with sporadic nontoxic goitre.

Esophageal transit (E.T.) was investigated in 122 consecutive euthyroid patients with scintigraphically proven goitre, and compared to 26 control subjects. E.T. was quantified using the 81mKr transit time, a highly sensitive technique capable of detecting even minor E.T. disorders. Abnormal E.T. was observed in 39% of goitrous patients, while it was normal in all controls. Occurrence of delayed E.T. was not correlated with either goitre firmness, the presence of symptoms of neck discomfort, difficulties in swallowing, or nodularity. E.T. delay was more frequent and more severe with larger goitres. In addition, E.T. delay was significantly correlated with asymmetry and "low lying" goitres. In summary, the present studies are the first demonstration of frequent E.T. anomalies in goitrous patients. The data suggest that E.T. impairment could be mediated by two mechanisms: a direct compression effect in patients with large, asymmetrical, partially retrosternal goitres; and an indirect functional esophageal anomaly in patients with small goitres.

Adolescent↗
PubMed1985

Factor analysis of 81mKr lung ventilation studies.

Factor analysis of dynamic structures (FADS) summarizes data depending on time and space in a few elementary components. Each of them associates a time-activity curve (factor) and the spatial distribution of the corresponding events. The aim was to evaluate the patterns, the number of components, and their possible link to physiology when FADS was applied to scintigraphic images representing a composite of a 81mKr ventilation cycle. In a study of 26 patients (10 normal, 16 pathologic), components were found that represent: (1) a rapid and steeply changing ventilation factor, corresponding mainly to bases in normal subjects and whole lung fields in patients, (2) a slower expiration and shorter inspiration ventilation factor distributed throughout both lung fields in all patients, (3) a constant activity curve, with an inspiratory activity peak distributed over both lung fields and the large airways, and (4) a factor including a phase shift with respect to the first; this was found significantly more often in patients with pathology.

Factor Analysis, Statistical↗
PubMed1984

81mKr gas and 99mTc-MAA V/Q ratio images for detection of V/Q mismatches.

Methods for creating ventilation/perfusion ratio images have been reported previously using radioxenon. With the availability of 81mKr gas, corresponding ventilation and perfusion views in multiple projections to evaluate for V/Q mismatch may be performed more readily. A technique for the creation of a functional V/Q ratio image to highlight V/Q mismatches to aid in the evaluation of pulmonary embolism is described. By removing nonpertinent and distracting information and by converting a 'cold spot' imaging modality to a 'hot spot' modality, these functional images aid in the synthesis of the information provided by the ventilation and perfusion images. The limitations due to technical artifacts and the advantages of using these functional images are described.

Humans↗
PubMed1984

Quantitation of esophageal transit by means of 81mKr.

A method for quantifying esophageal transit by means of 81mKr is described. The principal advantage of 81mKr compared with 99mTc is its ultra-short half-life with its consequences on radiation dose and counting statistics. Factors which may influence the esophageal transit time such as body posture, volume of the tracer, and the nature of the tracer were studied. The reproducibility of the technique is quite good and its capacity to detect minor esophageal transit disorders is demonstrated.

Adult↗
PubMed1983

Silicon avalanche radiation detectors: the basis for a new in vivo radiation detection probe.

Recent advances in semiconductor technology have made it possible to develop practical silicon avalanche radiation detectors. These detectors are analogous in operation to a gas proportional counter, but are capable of extreme miniaturization. Most importantly these devices have overcome the in vivo limitations of past semiconductor detectors with respect to noise, microphonics, and adaptability to relatively harsh environments. The operation and some useful characteristics of an avalanche detector are outlined. The performance of a probe mounted detector in an in vivo setting is described which illustrates one application of the silicon avalanche detector in this milieu.

Animals↗
PubMed1984

A simple radioaerosol generator and delivery system for pulmonary ventilation studies.

Details of a simple radioaerosol generator and delivery system are presented. Aerosol streams of 99mTc-DTPA solution of different distributions were produced. The most useful distribution had an activity median aerodynamic diameter (AMAD) of 0.9 micron with a geometric standard deviation of 1.5. This distribution also had more than 96% of aerosol particles with aerodynamic diameter less than 2 micron. The system has been used for patient lung ventilation studies. The aerosol breathing-in period to achieve a satisfactory count rate was 1.8 +/- 0.38 min. The radioaerosol images were excellent and comparable to those obtained with 81mKr gas.

Aerosols↗
PubMed1982

The imaging of myocardial perfusion with 81mKr during coronary arteriography.

The use of 81mKr was investigated for imaging myocardial perfusion during coronary arteriography using conventional catheters. When the significance of stenosis judged by arteriography is unclear, the effect on tissue perfusion can be established and the contribution to collateral flow by each artery separately evaluated. The distribution of 81mKr, due to its 13-s half-life, represents regional blood flow. In order to evaluate interventions, studies can be repeated at a low radiation risk to patients. A sterile pyrogen-free 81Rb-81Kr generator was developed. With slow infusion, inadequate mixing and streaming takes place due to laminar flow in coronary arteries. Fast intermittent 3-ml 81Kr-dextrose bolus injections convincingly eliminated streaming artefacts. Imaging was performed in 13 patients with a mobile scintillation camera and digital imaging system. Blood flow was calculated using the inert gas washout technique. There was good correlation (r = 0.91) between coronary blood flow determinations using 81mKr and 133Xe respectively. The perfusion images correlated well with the coronary angiograms. Total coronary arterial occlusions as demonstrated by arteriography were all shown as perfusion defects during rest. During atrial pacing myocardial flow was increased two-fold in normal coronary arteries and to a lesser extent in arteries with significant disease. The most critical lesion in a branch of a left coronary artery leads to a redistribution of perfusion during pacing.

Angiography↗
PubMed1986

Assessment of SPECT ventilation-perfusion imaging in patients with lung cancer.

Ventilation and perfusion SPECT images during tidal breathing were studied in 15 cases of lung cancer using 81mKr gas and 99mTc-microspheres. Furthermore, functional images of V/Q ratio and Q/V ratio were prepared, and their clinical significance is discussed with reference to general lung function. There was a decrease in %VC and %FEV 1.0 in 7 of 15 cases, and an increase of AaDo2 in the blood gas analysis in 12 of 15 cases. Both planar and SPECT images showed ventilation and perfusion abnormalities in all 15 cases. Of these, 12 patients showed matched ventilation and perfusion defects, 2 patients a dead-space effect and 1 patient a shunt effect. In comparing planar and SPECT images, depiction of ventilation and perfusion impairments were equally clear in 11 cases, but in 3, showing a lobar or segmental defect with a shunt effect, the SPECT images were superior. In a patient with markedly impaired function of the affected lung, the remaining function could not be depicted by SPECT. From the above, it seems that better information can be obtained for understanding the ventilation and perfusion states of lung cancer by adding the SPECT images to the planar image.

Adult↗
PubMed1987

The distribution of lung damage in children with cystic fibrosis and its relationship to colonisation with Pseudomonas aeruginosa.

Ventilation-perfusion lung scans were performed with 81mKr inhalation and 99mTc-albumin injection in 33 children with cystic fibrosis. It was found that both ventilation and perfusion scans yielded more information than radiographs of the chest in assessing lung damage. Using a scoring system, it was demonstrated by statistical methods that in the worst affected patients the disease was worse in the upper zones of the lungs, which changes were not detectable on chest radiographs. Pseudomonas was present in the sputum of these patients.

Adolescent↗
PubMed1985

Evaluation of methods for qualitative and quantitative assessment of esophageal transit of liquid.

The aim of this work was to compare the advantages and the limitations of several data processing techniques for the assessment of esophageal transit. The following qualitative methods were evaluated: scintigraphic image, cine-display, regional time-activity curve, and condensed image. The quantitative methods evaluated were the pixel to pixel presentation of parameters of the time-activity curves such as time of arrival, time to maximum, and several downslope parameters, mean transit time, mean time, and a new transit parameter based on the radioactive decay. The study allowed us to conclude that for the detection and the quantitation of esophageal transit the method of choice was the combined use of the condensed image and the pixel to pixel mean time image. The parametric image using the transit parameter calculated from decay was shown as a valuable alternative if an ultra-short half-life radionuclide was used as the tracer.

Esophagus↗
PubMed1990

Lung scintigraphy clustering by texture analysis.

The efficiency of texture analysis parameters, describing the organization of grey level variations of an image, was studied for lung scintigraphic data classification. Twenty one patients received a 99mTc-MAA perfusion scan and 81mKr and 127Xe ventilation scans. Scans were scaled to 64 grey levels and 100 k events for inter subject comparison. The texture index was the average of the absolute difference between a pixel and its neighbors. Energy, entropy, correlation, local homogeneity and inertia were computed using co-occurrence matrices. A principal component analysis was carried out on each parameter for each type of scan and the first principal components were selected as clustering indices. Validation was achieved by simulating 2 series of 20 increasingly heterogeneous perfusion and ventilation scans. For most of the texture parameters, one principal component could summarize the patients data since it corresponded to the relative variances of 67%-88% for perfusion scans, 53%-99% for 81mKr scans and 38%-97% for 127Xe scans. The simulated series demonstrated a linear relationship between the heterogeneity and the first principal component for texture index, energy, entropy and inertia. This was not the case for correlation and local homogeneity. We conclude that heterogeneity of lung scans may be quantified by texture analysis. The texture index is the easiest to compute and provides the most efficient results for clinical purpose.

Humans↗
PubMed1997

Clinical assessment of fluorescence cytoscopy during transurethral bladder resection in superficial bladder cancer.

The prognosis of superficial bladder cancer in terms of recurrence and disease progression is related to bladder tumor multiplicity and the presence of concomitant "plane" tumors such as high-grade dysplasia and carcinoma in situ. This study in 33 patients aimed to demonstrate the role of fluorescence cystoscopy in transurethral resection of superficial bladder cancer. The method is based on the detection of protoporphyrin-IX-induced fluorescence in urothelial cancer cells by topical administration of 5-aminolevulinic acid. The sensitivity and the specificity of this procedure on apparently normal mucosa in superficial bladder cancer are estimated to be 82.9% and 81.3%, respectively. Thus, fluorescence cytoscopy is a simple and reliable method for mapping the bladder mucosa, especially in the case of multifocal bladder disease, and it facilitates the screening of occult dysplasia.

Adult↗