Biomedical subjects
Publications and source records attributed to A J Gilson.
We report a patient who had two episodes of bleomycin lung toxicity with a good clinical response following corticosteroid therapy. The first episode followed treatment with 120 units of bleomycin and was characterized by cough and dyspnea. The second resulted in ARDS following a surgical procedure that used an FIO2 level of 0.33.
No method has been reported for measuring CBF, repeatedly and noninvasively, in the rat brain. A new method is described, which is noninvasive to the brain, skull, or cervical large vessels. Two pairs of coincidence detectors were positioned, one over the rat brain and the other at the loop of a catheter inserted into the femoral artery. The coincidence head curve and arterial curve were recorded after intravenous injection of 1-[11C]butanol in 15 rats. CBF was calculated by one-compartment curve fitting ( CBFo ) from 1-min data and with the recirculation corrected height/area method from 3-min data ( CBFh X 3 min) and 5-min data ( CBFh X 5 min). CBFo agreed well with CBFh X 5 min, although a slight overestimation was observed in CBFh X 3 min. The normal CBFo in the normocapnic group (n = 6, paCO2 36.7 +/- 2.3 mm Hg) was 1.76 +/- 0.49 ml/g min (mean +/- SD). A good correlation was observed between CBFo (y) and PaCO2 (x), and the regression line was y = 0. 0629x -0.715 (r = 0.88, p less than 0.0001). We concluded that this method gives the stable blood flow values noninvasively and with a minimum loss of blood (less than 0.28 ml per measurement). Applications of this method include activation studies, studies on the effect of drugs and treatments, and water and oxygen extraction fraction studies using different tracers in the same rat.
A mathematical method has been developed by which the cerebral vascular extraction fraction of flow- and diffusion-limited tracers injected intravenously can be measured quantitatively. Successive injections of three tracers are required: a test tracer such as 15O-labeled water; a completely diffusible tracer as a reference tracer and also as a flow tracer; and a tracer for cerebral blood volume (CBV). The arterial tracer concentration curves and total integrated head counts of the test and reference tracers, as well as CBF and CBV values, are required to calculate the extraction fraction. No calibration is required between the head counts and arterial curves. No decay correction of the head and arterial activity is required, because isotopic decay is explicitly included in the equation. The effect of nonextracted test tracer can be corrected. Simulation studies have shown that the calculated extraction fraction values are not sensitive to measurement error in CBF, CBV, partition coefficient, change in measurement time, or time shift effect between the arterial and head data. If there is mixing of two different tissues in the brain, the calculated extraction fraction values are close to the weighted mean values of extraction fraction by relative weight of the tissues. It is concluded that it is possible to apply this method to human studies with a positron emission tomograph scanner and to animal studies with external coincidence detectors.
Forty-four pathologically proved mammary carcinomas were studied by clinical examination, xeroradiography, and ultrasonography with a dedicated whole-breast scanner. Abnormalities reflecting carcinoma were shown by echography in 90% of cases and xeromammography in 97%. Ultrasonic manifestations of malignancy were separated into four categories: (a) a solid, hypoechoic mass; (b) a hyperechoic focus; (c) an irregular, echogenic zone of parenchymal disruption; and (d) an atypical cystic mass. Dedicated ultrasound instruments enhance interpretation and improve differential diagnostic capability. Sonography demonstrates abnormalities better and permits superior definition of abnormal characteristics in a dysplastic breast than in a fatty, atrophic breast, while xeromammography may be more reliable in postmenopausal women with fatty breasts than in women with mammographically dense breasts. One limitation of current ultrasound equipment is the inability to consistently demonstrate microcalcification.
We have developed a method for the synthesis of C-11 iodoantipyrine. Carbon-11-labeled methyl iodide, prepared from 11CO2, was used to methylate 3-methyl-1-phenyl-2-pyrazolin-5-one to form C-11 antipyrine. Following silica-gel column chromatography and iodination, radiochemical purity of the C-11 iodoantipyrine was more than 99.5%, with a 10% yield and a specific activity of 30 mCi/mumol. Preliminary animal studies showed complete cerebral extraction and local cerebral blood-flow values that were within 4.6% of those obtained using C-14 iodoantipyrine. The C-11 analog, with positron emission tomography, will facilitate local cerebral blood-flow studies in human subjects.
The scintigraphic and sonographic findings in 70 patients with pathologically confirmed gallbladder disease are described. Fifty-two patients were found to have had acute cholecystitis. All 52 patients (100%) had non-visualized of the gallbladder on scintigraphy. Of these patients, 71% had abnormal ultrasound examinations and 29% had normal ultrasound examination. Eighteen patients were proven to have chronic cholecystitis. All 18 (100%) had an abnormal ultrasound examination. Four patients (22%) had non-visualization of the gallbladder on scintigraphy producing a false-positive incidence of approximately 6% for acute cholecystitis. The predictive value of scintigraphy in the patient with suspected acute cholecystitis was 94%. A combination of ultrasound and scintigraphy yielded a sensitivity of 100% in the detection of gallbladder disease in the 70 patients.
Innovations in design of a dedicated breast scanner resulted in automation of the scanning process, the production of high resolution images of the whole breast and an efficient mode of image review. The results of clinical evaluation of the prototype of this breast scanner investigating normal breasts as well as benign and malignant breast lesions are presented.
Static radionuclide images of subacute subdural hematomas demonstrate significant variations in findings over a 3-hr period in the same patient. The lesion can appear, disappear, and reconstitute in an entirely different pattern. This transformation has not appeared in extradural hematomas, and may provide a differential diagnostic sign. In patients with a clinical history or physical findings suspicious for these intracranial hematomas, immediate and sequential delayed static imaging is recommended.
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A method for the detection and quantification of left-to-right intracardiac shunts is described which utilizes a single breath inhalation of oxygen-15 labeled carbon dioxide (C15O2). The inhaled gas rapidly crosses the alveolar membrane and the oxygen-15 label is exchanged through the carbonate cycle to form oxygen-15 labeled water within the pulmonary capillary blood. Pulmonary indicator clearance curves are measured by external scintillation probes. A simplified method of shunt flow quantification was developed from indicator dilution principles and used for the analysis of the clearance curves. Inhalation studies were performed with 62 children on the day prior to cardiac catheterization. The presence or absence of left-to-right shunt was confirmed by contrast angiography in all cases. Twenty-six children were found to have no shunts by C15O2 inhalation, oximetry or angiography. Of the 36 with shunts, 34 were detected by C15O2. Two of these were designated as equivocal because they were considered to be less than the threshold of definitive detection by C15O2 (having Qp/Qs less than 1.2); 32 were positive and there were two false negatives with small ventricular septal defects. There were no false positives by C15O2. The correlation coefficient between C15O2 and oximetry values of shunt flow for those patients with proven shunts was 0.82.
A new technique for the study of cardiac hemodynamics is described which utilizes single-breath inhalation of C15O2 (T 1/2 = 124 sec.) and the recording of activity vs. time curves with scintillation counters placed externally over the left ventricle and right lung. The results from 10 normal volunteers and 28 patients with acquired or congenital heart disease have been compared to the findings at cardiac catheterization. The technique is safe, rapid, and nontraumatic, and yielded no false positives or negatives in this series.
Accelerator-produced C15O2 (t 1/2 = 124 sec) is a uniquely useful radiopharmaceutical because it can be introduced rapidly and selectively into the left side of the heart by the simple noninvasive process of inhalation and breath-holding. A standard scintillation camera system was used to obtain images of the left heart by this technique. The procedure involves minimal radiation dose to the patient and may be repeated within a few minutes if necessary.
A practical method for preparing )23-I-rose bengal that allows for its rapid and efficient incorporation into the molecule is reported. Administration of 123-I-rose bengal to normal healthy patients showing the normal uptake and excretory pattern visualized with this radio pharmaceutical is also presented. The overall reduction in imaging time and radiation exposure together with the improved images possible should greatly improve our diagnostic capabilities in evaluating the jaundiced patient.
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