The construction and use of nomograms for cerebral blood flow calculation using a 133Xe inhalation technique

Measurement of cerebral blood flow (CBF) using a 133Xe inhalation technique requires monitoring the clearance rate of the radioisotope from the head using externally situated detectors and also from arterial blood using a detector to monitor the expired air activity. The end-tidal concentration function is assumed to be proportional to the arterial concentration function and this has to be deconvoluted from the clearance functions obtained from the head to enable CBF to be calculated. A digital computer is generally considered to be essential for this. In this paper a procedure using three-dimensional nomograms is derived and tested. It is shown that results obtained using the nomograms do not differ significantly from results obtained using a full deconvolution procedure, and so it is not essential to use a computer to calculate CBF by the inhalation technique.     

Even distribution of 133Xe bolus inhaled at residual volume in healthy subjects

We selected from among 46 healthy students (22 to 31-yr-old) 7 subjects (group A) in whom the normalized height of phase IV (height of phase IV/phase IIIx100), after inhaling a bolus of He at RV, was very small (10%). We compared them with 6 subjects (group B) selected on the basis of a tall phase IV (78%, A vs. P P less than 0.005). Age and height were comparable, but weight was lower (P less than 0.05) and RV/TLC ratio (but not other spirographic indices) was larger (P less than 0.025) in group A. The average amplitude of cardiac oscillations was 4 times higher in group B (P less than 0.005). He closing volume, but not closing capacity was less in group A (P less than 0.05). A bolus of 133Xe inhaled at RV was nearly uniformly distributed in group A while producing a large vertical gradient in group B. The difference between groups A and B may reflect a difference in the mechanical properties of the chest wall leading to a less complete empting of the lung in the former group.     

Radiopharmacology of inhaled 133Xe in skeletal sites containing deposits of Gaucher cells

Gaucher's disease is a lysosomal storage disease in which cells of the reticuloendothelial system accumulate the lipid glucocerebroside. It is characterized by slowly progressive visceral and osseous involvement. One of the latter manifestations includes lipid infiltration of bone marrow. We monitored the rate of inhaled 133Xe uptake and wash-out over diseased and normal metaphyseal and epiphyseal areas of the knee. Twenty-two patients (15 adults, 7 children) with various degrees of previously diagnosed Gaucher's disease were positioned supine under a gamma-camera interfaced to a computer system. All patients rebreathed 133Xe gas from a closed system for 10 min followed by 14 min of wash-out. Digitized images of the lung, liver, spleen, bony sites and soft tissue were obtained at 1 min intervals during the wash-in and wash-out phases. Counts for each ROI were normalized per 100 pixels and plotted as a function (time). Maximum uptake was also calculated by relating the counts/ROI/100 pixels to the 10 min integrated lung count during equilibrium (the administered "dose"). There was essentially no 133Xe uptake in liver and spleen involved with Gaucher's disease. Monophasic uptake and biphasic wash-out curves were observed in the limited investigative population. Skeletal Gaucher deposits released the 133Xe at a greater rate relative to soft tissue.     

A scintigraphic method of examining the patency of oviducts using 133Xe

Described below is the radioisotope method of examining the patency of oviducts using a solution of 133Xe. Scintigraphic pictures of the uterine cavity and oviducts were obtained with a Jumbo Toshiba gamma-camera; they were subsequently analysed by an Informatek SIMIS-3 data processing system. A total of 30 women aged between 20 and 36 with primary or secondary infertility were examined. The patency of oviducts and the shape of the uterine cavity was assessed on the basis of: the overall picture of the activity of 133Xe in the uterine cavity and oviducts, the isocontours of the overall picture, curves of increasing and decreasing activity in the fallopian tubes, and the spatial picture of activity distribution in the uterus and fallopian tubes. The results of the examinations corresponded in all cases with the diagnosis made on the basis of hysterosalpingography. An advantage of the isotope method of examining the patency of fallopian tubes and the shape of the uterine cavity is the fact that it is an examination of a dynamic nature, completely safe for the patient and exposes the patients to a considerably lower dose of irradiation than during hysterosalpingography.     

Radiation safety

Nursing and radiology staff members can have a difficult time coexisting and communicating as they strive to provide quality care for patients. Misconceptions about safe radiologic practice within the practice of perioperative nursing occur because members of these professional fields are unfamiliar with each other's knowledge and practice guidelines. This article provides an overview of radiologic practice and safety.     

Influence of posture on flow dependence of distribution of inhaled 133Xe boli

The second 100 ml of gas inspired at constant flow rates (V) from 0.1 to 2.5 l/s was tagged with 133Xe to determine the apicobasal bolus distribution ratio (VAlvA/VAlvB) for seven normal subjects in both the upright and supine postures. Gas was preferentially distributed to the base at low V. As V increased, redistribution to the apex occurred but was greater in the supine posture. As apicobasal time constant differences should be minimal in the supine posture, the greater flow dependence of bolus distribution suggests that the pressure swing was greater over apical zones than basal zones. Model studies indicate that the pressure differences (deltaPd) necessary to predict the measured VAlvA/VAlvB at all flow rates are less than 1.0 cmH2O. Such sensitivity of gas distribution to deltaPd at both low and high flow rates makes it appear relatively insensitive to regional compliance and resistance.     

Calculation of coronary blood flow from myocardial clearance of systemically administered 133Xe

Clearance curves for arterial and coronary-venous blood were determined after systemic left-ventricle or pulmonary-artery infections of 133Xe, paired with selective left-coronary-artery injections of 133Xe in 20 dogs with closed chest. Coronary blood flows calculated from systemic and coronary-artery injections were comparable only when a correction was made for arteriol recirculation of 133Xe following the systemic injection (r = 0.962) for left ventricle and 0.932 for pulmonary artery, paired with coronary artery). Experiments in four other dogs, verified that clearance of 133Xe from the pulmonary circulation was only about 60%. The myocardium/blood 133Xe partition coefficient, determined in vivo in ten dogs, agreed within 10% with that previously determined in vitro.     

Regional cerebral blood flow determination using 133Xe and a standard rotating gamma-camera

While most of the methods for quantitative regional cerebral blood flow (rCBF) determination in man requires expensive fast devices, a method is proposed using single photon emission computed tomography with a conventional rotating gamma camera and 133Xe inhalation. It is tested using a computer simulation of a cerebral exam and a simplified CBF map as a model. The results obtained show that this method is relevant and can be tested in clinical studies.     

Detection of acute rejection by 133Xe radiospirometry after single lung transplantation in an experimental porcine model

153 regional lymph nodes obtained during surgical operations because of cancer of various cites from 50 cancer patients were studied. Failure of local immunity is explained by the following factors: 1) depletion of T-cell population with a decrease of activated lymphocyte-killers; 2) high activity of B-cell population able to block T-cell cytotoxic effect; 3) deficiency of T-suppressors and T-helpers; 4) a decrease of macrophages-monocytes of phagocytic capacity; 5) high activity of dendritic reticular cells stimulating transformation of B-lymphocytes and low activity of interdigitating reticulocytes determining T-cell immunity stimulation.     

Radiation safety in the cardiac catheterization laboratory

Over the years, permissible radiation exposure of operators working with x-ray equipment has become progressively reduced. The number of cardiac catheterizations and related interventional procedures has increased and the procedures have become more prolonged. The patient receives relatively infrequent primary radiation while the operator receives frequent but mainly secondary radiation. The operator uses protective barriers, correct positioning of the patient and careful techniques to reduce radiation exposure. The effects of radiation are cumulative and permanent. They may be stochastic or nonstochastic, and somatic and/or genetic, and onset may be delayed for many years. To minimize exposure of patient and operator, cardiologists need a better understanding of radiation physics and of cardiac x-ray equipment. Technical breakthroughs such as digital imaging, pulse fluoroscopy, reduction of frame rates from 60 or 30 frames/s to 15 frames/s, and progression to the filmless laboratory will substantially reduce radiation. This review discusses current cardiac x-ray equipment, possible future developments, radiation, and techniques for reducing radiation and improving safety in the cardiac catheterization laboratory.     

Studies on 133Xe wash-out from human skin: quantitative measurements of blood flow in normal and corticosteroid-treated skin

Blood flow was measured by the 133Xe technique in normal and corticosteroid-treated skin. Epicutaneous and intracutaneous methods of tracer application were compared in normal skin. The two labeling methods were equally suitable for measuring cutaneous blood flow provided calculations in both cases were based on a biexponential resolution of the wash-out curve in its cutaneous and subcutaneous components and provided the traumatic hyperemia phase was considered, when intracutaneous application of the tracer was used. Results were invalidated if calculations were based on initial slope of the wash-out curves.Topical application of beta-methasone valerate in a reduction in cutaneous blood flow as measured by the intracutaneous technique with curve resolution, whereas no effect could be demonstrated when calculations were based on the initial slopes of the curves. The 133Xe technique is a simple and reliable method for measuring cutaneous blood flow, which might prove useful in estimations of penetration ability and potency of topical corticosteroids.     

Synthetic peptides for diagnostic use

Interdisciplinary teaching rounds were initiated on a general surgery service at a university teaching hospital. These rounds were designed to promote more efficient patient care by providing an opportunity for enhanced communication among health-care professionals. Improved collaboration is a prerequisite for implementation of critical paths and case management. The authors describe their methods of rounds development and the impact of the rounds on patient outcomes.     

The use of biotechnological recombinant-mice in biological safety research

Number of transgenic and knock-out mice increased rapidly during the last decade. This review article describes a potential usefulness of transgenic and knock-out mice for biological safety research with respect to each toxicological category for safety evaluations, such as studies for carcinogenicity, general toxicology, genotoxicologic testing, and immuno-toxicological evaluations. In the carcinogenicity, a possible model required for a short-term study in carcinogenicity was discussed. Further, a couple of future subjects were focused specifically on the biotechnology-derived pharmaceuticals and the biotechnical recombinant-mice as a second generation, i.e. experimental mice with double or multiple gene-recombination. Those usefulnesses were also introduced briefly. Establishing the biotechnical recombinant-mice for each safety testing contributes not only to simplify and qualify the on-going evaluation system, but also to the traditional animal studies to be re-evaluated, so that the solutions may lead them to a future in vitro-alternative system much smoothly. For general references, historical reviews on the biotechnical recombination in experimental animals were also briefly introduced to elucidate a new broad area in developmental biology.     

The use of dietary loading of 133Cs as a potassium substitute in NMR studies of tissues

133Cs NMR chemical shifts and relaxation times have been measured for tissue samples in vitro and in vivo from rats which have been fed on a high cesium, low potassium diet, which leads to a predominantly intracellular distribution of this ion, similar to that of K+. The high sensitivity, large chemical shift range, and narrow linewidths of 133Cs, compared with 39K, allow chemical shift differences to be observed between tissues, and in subcellular organelles such as mitochondria. For example, in vitro tissue chemical shifts, relative to 150 mM CsCl, are 1.06 +/- 0.11 ppm for liver, 0.02 +/- 0.05 ppm for brain, 1.76 +/- 0.20 ppm for erythrocytes, and -0.13 +/- 0.02 ppm for plasma. T1 and spin-echo T2 values range from 1.26 +/- 0.05 s (T1), and 0.028 +/- 0.006 s (T2) for liver, to 6.49 +/- 0.19 s and 1.12 +/- 0.03 s for plasma. 133Cs relaxation times show the same relative trends between tissues as are observed in 39K tissue studies.