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At least 721 records · Page 40Linked to original sources
PubMed1993

Review of laser treatment at Keio University Eye Clinic.

Between 1978 and 1992, 5310 eyes in 4317 cases were treated by laser photocoagulation at our clinic. Argon, krypton and dye lasers with slit lamp microscope were used 7556 times for 4446 eyes. Main indications included diabetic retinopathy, retinal vein occlusion, retinal break and glaucoma. For treatment of these diseases, argon blue-green and green laser were chosen in majority of cases. Macular diseases were treated most frequently by krypton laser. Endophotocoagulation by argon laser during vitreous surgery was performed in 399 eyes mainly with diabetic retinopathy, retinal detachment and retinal vein occlusion for 7 years. Treatment by Nd: YAG laser was done in 465 eyes for 5 years and more than 90% of cases were performed capsulotomy for after-cataract. Numbers of cases treated by any kinds of laser is increasing with the years.

Glaucoma↗
PubMed1979

Choroidal blood flow. IV. effect of vasodilating agents.

The effect of vasodilators on choroidal blood flow (CBF) was studied by the krypton clathrate Kr 85 desaturation technique in anesthetized cats. Niacin, papaverine hydrochloride, phentolamine mesylate, and tolazoline hydrochloride were injected via the lateral long posterior ciliary artery (LLPCA) and the femoral artery. The systemic administration of these drugs via the femoral artery, in the doses used, had no significant effect on mean arterial pressure, choroidal vascular resistance (CVR), or CBF. Local administration of the same agents via the LLPCA caused a decrease in CVR with a corresponding increase in CBF.

Animals↗
PubMed1985

Simulated treatment of recurrent choroidal neovascularization in primate retina. Comparative histopathologic findings.

We simulated the treatment of recurrent choroidal neovascular membranes (CNVM) by applying two courses of laser treatment to monkey retinas. Argon green, argon blue-green, and krypton red lasers (KRLs) were used in juxtafoveal, papillomacular bundle, and nonmacular areas. The effects were examined clinically and histopathologically. Results of once-treated control eyes were consistent with those of previous studies. Repeat treatment, however, resulted in full-thickness retinal destruction or necrosis with all laser modalities and in all fundus locations. These results are consistent with the absorptive characteristics of xanthophyll and melanin and suggest only limited advantages to the KRL when treatment of recurrent CNVM is performed in a previously treated area of the fundus. However, treatment of recurrent CNVM is still probably most successful with a KRL, because recurrent CNVM is usually at a border of a photocoagulation scar, where the retina is still untreated, and because histologic studies have demonstrated inner retinal sparing with a KRL in juxtafoveal areas.

Animals↗
PubMed1988

Laser treatment for choroidal neovascularization outside randomized clinical trials.

This study was undertaken to determine whether the treatment benefit reported in randomized trials for patients with extrafoveal choroidal neovascular membranes (NVMs) secondary to age-related macular degeneration (AMD) or the ocular histoplasmosis syndrome (OHS) can be duplicated in other clinical settings. The visual results and recurrence rates in treated extrafoveal NVMs of 70 patients with AMD and 21 patients with OHS were similar to those reported by the Macular Photocoagulation Study Group, in which all treated patients received argon blue-green laser photocoagulation after the administration of retrobulbar anesthesia. In this study, 78% (71/90) of the patients were treated with krypton laser and only 35% (32/90) had retrobulbar anesthesia. These results suggest, but do not prove, that the wavelength of the laser used or the administration of retrobulbar anesthesia may not be critical variables in determining the success of treatment in patients with extra-foveal NVMs.

Argon↗
PubMed1982

Fluorescence bronchoscopy in the localization of bronchogenic carcinoma.

Fluorescence bronchoscopy using hematoporphyrin derivative as a tumor marker has been developed for localization of early bronchogenic carcinoma. Recent clinical results have been obtained with a krypton laser and a fused quartz fiber illumination system, which is clearly superior to the mercury vapor lamp system used previously. Fifteen patients have been examined, two with the laser. The potential of the technique is demonstrated by a case study of a patient with positive sputum cytology and a negative chest radiograph. The small early invasive tumor could be detected only with difficulty by subtle mucosal changes under white light bronchoscopy. Positive fluorescence was observed in the suspicious area. Malignancy was confirmed by biopsy and histologic examination upon subsequent lobectomy.

Aged↗
PubMed1985

Changes in distribution of hepatic blood flow induced by intra-arterial infusion of angiotensin II in human hepatic cancer.

Changes in the distribution of the hepatic blood flow induced by intra-arterial infusion of angiotensin II (AT-II) were studied in human hepatic cancers using extremely short-lived radioisotope (RI) (krypton 81 m [81mKr]; half-life, 13 seconds). After the start of continuous infusion of AT-II, the radioactivity of the tumor showed about a two-fold increase, whereas that of the nontumor region decreased to about one half as much as the level before the infusion. Consequently, the mean ratio of the arterial blood flow in the tumor region to that in the nontumor region (T/N ratio) increased to 3.30 (P less than 0.001). The T/N ratio showed a peak before the peripheral blood pressure reached the maximum, and thereafter tended to decrease. Intra-arterial infusion of AT-II raised the T/N ratio more obviously than did intravenous infusion of the drug, with less rise in the peripheral blood pressure. It is believed that intra-arterial infusion chemotherapy with local use of AT-II enables better accessibility of chemotherapeutic drugs to tumors.

Adenocarcinoma↗
PubMed1978

An isotope clearance method for measurement of liver blood flow during portasystemic shunt in man.

The clearance from the surface of the liver of krypton 85 following its injection into the portal vein was measured in 10 patients. Six control patients (i.e. those not suffering from portal hypertension) averaged flow values of 142 ml per 100 g liver weight per min. A repeat flow estimation in these patients was not significantly different. Four patients with portal hypertension were studied. In 2 with congenital hepatic fibrosis the portal vein was temporarily occluded to allow prediction of the degree of hepatic perfusion likely to be achieved by the hepatic artery alone after portal deviation. The flow after portal venous clamping was unaffected in one of these cases but reduced by 45 per cent in the other. In a patient undergoing a Warren distal splenorenal shunt there was no change in flow after the procedure. If measurements are performed before and during temporary portal vein occlusion, an assessment of the flow reduction to be expected after a shunt procedure can be made. We suggest that a knowledge of liver tissue perfusion might influence the choice of operative procedure.

Blood Flow Velocity↗
PubMedDate not supplied

Determination of right ventricular ejection fraction in children with cystic fibrosis.

The radionuclide right ventricular ejection fraction (RVEF) determined by means of Krypton-81m represents a simple, noninvasive, and accurate procedure to quantify the right ventricular contractility. This procedure was applied to 25 young patients with cystic fibrosis. The RVEF tended to decrease with the progression of the lung disease, as assessed by the clinical S-K score, the degree of the defects on lung scintigraphy, the PaO2, and the lung function tests. However, the decrease of RVEF in patients with marked lung function tests. However, the decrease of RVEF in patients with marked lung involvement was moderate, and terminal lung disease was sometimes associated with normal right heart contractility.

Adolescent↗
PubMed1992

Effect of posture on regional ventilation in children.

Little information has been published concerning the pattern of regional ventilation in children, yet many differences in lung and chest wall mechanics in childhood, supported by clinical observation, have led to the hypothesis that the pattern of regional ventilation seen in children may not be the same as in adults. Forty-three children and 16 adult volunteers underwent Krypton (Kr) 81m radionuclide ventilation lung scans in the supine and right and left decubitus postures. In children aged 2-10 years mean fractional ventilation to the right lung (VfR) was 46.1%. This fell to 36% when dependent and rose to 56.1% in the uppermost position. Redistribution of ventilation away from the dependent towards the uppermost lung was seen in all children. In children aged 10-18 years VfR was 57.2% (supine), 48.0% (dependent), and 62.9% (uppermost). An identical pattern was seen in children with normal or abnormal pulmonary function tests (peak expiratory flow rate, and FEV1: FVC ratio). In subjects over 18 years of age a different pattern was seen: mean VfR was 52.4% (supine), rising to 53.4% (dependent), and falling to 48.9% (uppermost). Postural redistribution of ventilation, as assessed by Kr81m ventilation imaging, changes late in the second decade of life. This will have clinical consequences in the management of children with unilateral lung disease.

Adolescent↗
PubMed1999

An experimental study of the isotopic enrichment in Ar, Kr, and Xe when trapped in water ice.

The isotopic enrichment of argon, krypton, and xenon, when trapped in water ice, was studied experimentally. The isotopes were found to be enriched according to their (m1/m2)1/2 ratio. These enrichment factors could be useful for comparison among the uncertain cosmic or solar isotopic ratios, the hopeful in situ cometary ratio, and those in Earth's atmosphere, in the context of cometary delivery of volatiles to Earth.

Argon↗
PubMed1986

Automated determination of the right ventricular ejection fraction by digital processing of 81mKr scintigrams.

A method is presented for the automated determination of the right ventricular ejection fraction (RVEF) by digital image processing of scintigrams obtained by intravenous infusion of Krypton 81m (81mKr) dissolved in a glucose solution. End-diastolic and end-systolic sum pictures were computed by the addition of approximately 30-40 frames selected from the time-activity curve of a preliminary, manually drawn, right ventricular region of interest. After processing these two images with an adaptive Wiener filter, the right ventricular contour was determined by a recently developed algorithm using morphological and functional criteria. The RVEF was calculated for a series of 51 patients from the counts in the detected right ventricular regions in the end-diastolic and end-systolic sum images. In 16 patients without evidence of cardiopulmonary disease, the mean RVEF was 50 +/- 6.1%. RVEF was significantly reduced in 18 patients with obstructive pulmonary disease (42 +/- 6.5%) and in 17 patients with congestive cardiomyopathy (36 +/- 7.1%). The correlation coefficient between two determinations of the RVEF was r = 0.94. Through digital image processing, the determination of the RVEF by radioventriculography with 81m Kr showed high reliability and reproducibility.

Algorithms↗
PubMed1987

The use of a computer in ventilation-perfusion scintigraphy with Tc-99m macroaggregates and Kr-81m, to obtain a physiological model.

In this article we describe a computer program to demonstrate ventilation-perfusion relationships in the lungs, using 99mTc-MAA and 81mKr, with the patients sitting upright, the normal physiological situation. The ventilation and perfusion scans are performed simultaneously with both gamma camera and computer adjusted for dual isotope mode. Steady state images are acquired in the frontal, dorsal, and left and right posterior oblique positions. Additionally, in the dorsal and frontal projections, a sequence of 12 washout images (5 s) is registered, after closing the Krypton supply. After normalization and further computer processing, the following parameters are calculated in the frontal and dorsal projections, in the whole lung and in four horizontal subregions: washout values, ventilation-perfusion ratios, left to right ratios of ventilation and perfusion, and left to right ratios of the average pixel values for ventilation and perfusion. Results in a group of eight healthy volunteers are described and discussed.

Adult↗
PubMed1983

Regional distribution of ventilation and perfusion in patients with obstructive pulmonary disease and alpha 1-antitrypsin deficiency.

Regional distribution of pulmonary ventilation and perfusion has been determined of 13 patients with chronic obstructive pulmonary disease (COPD). Eight patients had alpha 1-antitrypsin deficiency (alpha 1 ATD). Ventilation studies were carried out using xenon-133 (133Xe) and krypton-81m (81mKr) gases. Trapping indices were determined from the wash-out part of the xenon ventilation studies. Results obtained from patients were compared with those of normal controls. Ventilation studies with 81mKr showed pulmonary changes more clearly than did 133Xe studies and the trapping of radio-xenon was more extensive in lung bases than in apices whether or not the patients had alpha 1 ATD. The distribution of perfusion followed a pattern similar to that of ventilation, but did not differ statistically from that of the normal controls.

Humans↗
PubMed1981

Ventilation imaging with Kr-81m. A comparison with Xe-133.

Sixty-five patients with suspected pulmonary embolism were studied prospectively with both Kr-81m and Xe-133 ventilation imaging and Tc-99m MAA perfusion imaging. The krypton images, perfusion scintigrams and chest radiographs were read independently of the xenon images, perfusion scintigrams and chest radiographs by three observers. The studies of 53 patients were interpreted as normal or as indicative of a low or intermediate probability for pulmonary embolism with both gases. One study indicated intermediate probability with Xe-133 due to diffuse, severe xenon retention but low probability with Kr-81m because of close ventilation-perfusion correspondence. The studies of 9 patients indicated a high probability of embolism with both gases, while those of two additional patients (one with emboli at angiography) indicated a high probability only with Kr-81m. While essential agreement between Xe-133 and Kr-81m ventilation imaging was found in most patients, the significant difference in interpretation in 2 of 11 patients with probable pulmonary embolism suggests that a controlled, prospective trial with pulmonary angiography is warranted before Kr-81m is employed for routine clinical use.

Humans↗
PubMed1984

Regional distribution of ventilation-perfusion ratios in acute pulmonary embolism.

Regional ventilation perfusion ratios have been computed in 44 patients with acute pulmonary embolism with a gamma-camera using Krypton 81m, a short-life radionuclide delivered by inhalation and infusion. This noninvasive technique is performed during tidal breathing and can be easily repeated. High V/Q's are detected in the embolic regions and low V/Q's in the nonembolic regions with a shift of the perfusion distribution towards these low values. This pattern disappears with recovery. This technique can be used in clinical practice for diagnostic purposes.

Acute Disease↗
PubMedDate not supplied

Myocardial perfusion measured by dual-isotope acquisition of 81rubidium/81mkrypton: an experimental verification of the method.

PURPOSE: The purpose of the study was to verify that the 81Rubidium/81mkrypton (81Rb/81mKr) method allows the quantitative measurement of myocardial perfusion. PRINCIPLE: The potassium analogous cation 81Rb is accumulated in the myocardium by the cell membrane-bound Na-K-ATPase. After accumulation an intracellular equilibrium establishes between 81Rb and its radioactive daughter nuclide 81mKr. The flow-sensitive method evaluates the disturbance of this equilibrium by perfusion which washes out the short-lived diffusable daughter nuclide 81mKr while the mother nuclide 81Rb remains cell-bound. METHODS: Isolated rabbit hearts were prepared in a modified Langendorff technique which allowed quantitative collection of the coronary sinus efflux. The myocardium was labeled with pure 81Rb by bolus injection into the aortic cannula. Spectroscopic measurements of 81Rb and 81mKr gamma radiation were performed using a germanium detector. Perfusion was varied in the range between 0 and 4 ml/min/g. The activity ratio 81Rb/81mKr was determined and compared with coronary sinus effusion. RESULTS: 81Rb/81mKr activity ratio was closely related (r = 0.98) to perfusion as described by the predicted equation Rb/Kr = (F/2.96 P) + 1. (Rb/Kr = activity ratio between 81Rb and 81mKr in the myocardium; F = myocardial perfusion (ml/min/g); P = partition coefficient (myocardium/perfusate) for Krypton gas). The constant P was found to be 1.14 +/- 0.06 (mean +/- SEM). No saturation of this ratio at high flow rates was observed. CONCLUSION: The activity ratio 81Rb/81mKr is a valid quantitative measure for myocardial perfusion in isolated hearts. The main limitation of the method before application in man is the correction of the different gamma ray tissue absorption of both nuclides.

Animals↗
PubMed1996

Oesophageal motility disorders in patients with psychiatric disease.

Clinical and experimental observations indicate that the motility of the oesophagus may be affected by emotional stimuli. The aim of this study was to evaluate the incidence of oesophageal contractility impairment in patients suffering from a psychiatric disorder. Fifty-one patients admitted to the psychiatric department were submitted to an oesophageal transit study by means of krypton-81m. All patients with an abnormal oesophageal transit underwent manometry and endoscopy. The level of depression and anxiety was evaluated by the treating psychiatrist, using the Hamilton Depression and Anxiety Rating Scales. The oesophageal transit was abnormal in 13 patients. Two of these 13 patients refused manometric investigation. In ten of the 11 remaining patients, the manometry revealed functional motor abnormalities. Endoscopy, performed in all these ten patients, was normal. In conclusion, a high percentage of oesophageal contractility disturbances was found in psychiatric patients complaining of anxiety and/or depression. These abnormalities were detected by scintigraphy as well as by manometry. Owing to the normal endoscopic findings, these contraction abnormalities are likely to reflect a functional motor impairment.

Anxiety↗
PubMed1980

99mTc-MDP extraction in relation to 81mKr perfusion following a partial osteotomy in the dog tibia.

The bone mineral extraction of technetium-99m-methylene diphosphonate (99mTc-MDP), and blood supply of Krypton-81m (81mKr) have been compared in normal and osteotomy regions of the canine tibia. A partial osteotomy was carried out under aseptic conditions, and isotopic measurements made over a period of 123 days. Both blood flow and bone mineral extraction increase after a partial osteotomy.

Animals↗