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At least 343 records · Page 19Linked to original sources
PubMed1983

A pressure independent orifice equation for the estimation of diastolic mitral valve area in mitral insufficiency: correlation with cardiac catheterisation data using a radioactive Krypton indicator method for the determination of regurgitant filling volume.

We have investigated the application of an hydraulic orifice equation for the computation of diastolic mitral valve area in conditions of regurgitation. The new equation is given by Af = 21 Vf/T2, where Af is the total forward flow mitral valve area in cm2, Vf is the diastolic filling volume in ml, T is the diastolic filling period and 21 is a discharge coefficient derived from clinical haemodynamic data. Areas computed by the new formula correlate with valve areas as computed by the Gorlin formula at a level given by r = 0.93, n = 27. The results suggest that the new formula may be utilised in the context of mitral insufficiency and further, considerating the nature of the haemodynamic variables involved, an echographic quantification of this condition by M-mode or bidimensional echocardiography may be possible.

Cardiac Catheterization↗
PubMed2002

Relative thermoluminescence efficiency of TLD-600 and TLD-700 dosemeters irradiated with 59.8 MeV per nucleon krypton-86 ions.

A batch of LiF thermoluminescence dosemeters (TLDs), each containing five TLD-600 and TLD-700 thermoluminescence dosemeter chips, was irradiated with 59.85 MeV per nucleon 86Kr20+ ions from the K1200 superconducting cyclotron at the National Superconducting Cyclotron Laboratory (NSCL). Michigan State University, USA. The average linear energy transfer of the accelerated 86Kr ions and the resulting dose imparted to the TLD chips were calculated to be 3343 keV.microm(-1) per ion and 1.68 Gy respectively. A similar batch of TLD chips was irradiated with 1.3 MeV gamma rays from a 60Co source to 1.0 Gy. The TLD chips were evaluated at a ramp heating rate of 10 degrees C.s(-1) to 400 degrees C using a hot-finger type TLD reader. The thermoluminescence efficiency of the TLD-600 and TLD-700 dosemeters, relative to 60Co gamma rays was calculated to be 0.0025 and 0.0027 respectively

Fluorides↗
PubMed1994

Technegas versus krypton-81m gas as an inhalation agent. Comparison of pulmonary distribution at total lung capacity.

Exactly how the pulmonary distribution of inhaled radioactive gas and Technegas, or ultra-small aerosol particulates, differs from each other, is still uncertain. The authors compared the distribution of inhaled Kr-81 m gas and Technegas in the lungs at total lung capacity in 13 control subjects with no clinical conditions and 13 patients with various chest diseases. In normal lungs, there was no difference in the distribution ratios in the right and left lungs between inhaled Kr-81m gas and Technegas. However, there was a significant difference in the lungs of patients with pulmonary disease. Technegas tended to deposit more in the lung bases than did Kr-81m gas. Despite these statistical differences, they were visually, or qualitatively, similar. From a practical and clinical standpoint, Technegas seems to be useful as an inhalation agent, unless quantitative analyses are required.

Administration, Inhalation↗
PubMed1990

Comparison of technetium-99m aerosol and krypton-81m in ventilation studies for the diagnosis of pulmonary embolism.

A new method of producing aerosols (technegas) in which 99Tcm is bound to carbon atoms (99Tcm-C) was evaluated by comparing 99Tcm-C images with those obtained with 81Krm in the same patients. Twenty-five patients with suspected pulmonary embolism (PE) were studied. Immediately after the last 99Tcm-C view, the patients remained in supine position and inhaled 81Krm at tidal volume. Immediately after the 81Krm ventilation views were recorded, 4-7 mCi of MAA were injected IV. The same four views (ant, lop, rop, post) were recorded after inhalation of 99Tcm-C and 81Krm (200 kcounts) and 99Tcm MAA injection (400 kcounts). The mean penetration index of 99Tcm-C (0.91) was lower than that of 81Krm (1.04) (P less than 0.03). The apex to base lung distribution of 99Tcm-C and 81Krm appeared to be similar. The mean heterogeneity of 99Tcm distribution was 23, greater than that of 81Krm (14) (P = 10(-4)). The 99Tcm-C ventilation image quality was considered very good for 16 patients and good for 6 others. Significant foci of high bronchial uptake were infrequent. Interpretation of the examinations performed after inhalation of 99Tcm-C and 81Krm was concordant in all cases. No patient had an 81Krm/99Tcm MAA examination suggestive of PE when 99Tcm-C/99Tcm MAA indicated a low probability of PE, and vice versa. 99Tcm-C aerosols enable good quality ventilation images to be obtained in nearly all cases. Thus 99Tcm-C aerosols could be used in preference to 81Krm in ventilation studies for the diagnosis of PE.

Administration, Inhalation↗
PubMed2005

Assessment of ventilation inhomogenity with Krypton SPECT and planar imaging.

In 29 chronic obstructive pulmonary disease (COPD) patients and nine lung healthy volunteers, above the age of 50 years, ventilation defects were examined by (81m)Kr planar scintigraphy and (81m)Kr single photon emission computed tomography (SPECT) to investigate if SPECT adds information regarding size and extent of visually scored ventilation defects, and to correlate the extent of defects obtained from the two imaging settings with standard pulmonary function tests performed in these patients/volunteers. For testing the reproducibility of the visual defect score of (81m)Kr scintigraphy additionally 13 patients suspected for pulmonary embolism or lung cancer were included. Each series of planar or SPECT studies were read for the extent (% abnormal lung) and severity (0-3) of ventilation abnormalities. Seventeen scans were read twice for reproducibility studies. The extent of ventilation defect assessed by (81m)Kr SPECT was higher than by (81m)Kr planar (slope of regression line 0.60, P<0.0001), likewise severity score (rank signed test: P<0.0001). Correlation between ventilation inhomogeneity and pulmonary function test (residual volume and T(L,CO)) in the COPD group revealed only significance for the SPECT acquisition. We found good reproducibility of visual assessment of ventilation defect extent (correlation: 0.97, P<0.0001) and severity (Kappa 0.62). In conclusion, visual scoring of extent and severity of ventilation defects was reproducible. Ventilation defects were better demonstrated with SPECT than planar imaging. The correlation to pulmonary function was better with SPECT than planar imaging.

Aged↗
PubMed1977

Testicular blood flow and a study of the testicular venous to arterial transfer of radioactive krypton and testosterone in the rhesus monkey.

1. Testicular blood flow (ml. 100 g(-1).min(-1); mean +/- S.E. of the mean) measured in monkeys by (133)Xe clearance was 15.9 +/- 1.2 (twenty-six estimations on three monkeys; six testes) within 15 min of anaesthesia and 7.5 +/- 0.8 (twelve estimates; four monkeys, eight testes), after 1-2 hr of anaesthesia; and, when measured by (85)Kr clearance in the second hour of anaesthesia was 9.1 +/- 3.7 (seven estimates; four monkeys, four testes). Testicular temperature was 32.9 +/- 0.2 degrees C (mean +/- S.E. of mean) when deep body temperature was 37.2 +/- 0.2 degrees C.2. Blood flow in the caput epididymidis was 27.4 +/- 2.1 ml. 100 g(-1).min(-1) (mean +/- S.E. of mean; four estimates).3. Radioactivity accumulated in the ipsilateral testis and epididymis but not in the contralateral tissues, during the infusion of (85)Kr saline into the testicular veins.4. During [(3)H]testosterone infusions into the testicular veins, radioactivity was consistently higher in ipsilateral testicular arterial plasma than in plasma withdrawn simultaneously from the aorta in four of five experiments with no difference in one. After two such infusions, the radioactivity was up to 5 times greater in the ipsilateral testis and epididymis than in the contralateral tissues.5. During one infusion of [(125)I]bovine serum albumin into the testicular veins, there was no accumulation of radioactivity in the ipsilateral tissues.6. Testosterone concentrations (ng.ml(-1); mean +/- S.E. of mean) in plasma from seven anaesthetized monkeys which were sexually experienced were: testicular vein 53.22 +/- 8.03 (eight estimates); testicular artery, 4.58 +/- 0.94 (14); saphenous vein, 3.81 +/- 0.68 (14). The corresponding values from four sexually inexperienced monkeys were 25.27 +/- 2.11 (12); 2.89 +/- 1.99 (12); aorta 2.76 +/- 0.57 (12).7. The results are discussed as evidence for vascular exchange of molecules between the testicular veins and artery in the spermatic cord.

Animals↗
PubMed1975

Assessment of regional ventilation by continuous inhalation of radioactive krypton-81m.

A simple technique is described for producing high-quality functional images of regional ventilation during physiological tidal breathing of the inert gas 81mKr. These images are quickly obtained on a gamma-camera without the need of computerized systems for data acquisition and display and are directly comparable with those of perfusion obtained with 99mTc-labelled macroaggregates. The short time required for the procedure, its simplicity, and the extremely low absorbed-radiation dose enable serial images of ventilation to be obtained in multiple views.

Dyspnea↗