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H H Hines

Publications and source records attributed to H H Hines.

14 recordsLinked to original sources
PubMed1986

Multicompartmental analysis of the kinetics of radioiodinated monoclonal antibody in patients with cancer.

A conceptual biologic model was developed and used to analyze the behavior of 123I-Lym-1 monoclonal antibody against African human B cell lymphoma in patients with B cell lymphoma. Originally, the observed data could not be simulated with parameters for homologous immunoglobulins reported in the literature because of a major processor that was capable of distinguishing this murine immunoglobulin from the patient's own immunoglobulins. With a nonlinear parametric model, the data observed in patients could be fitted to the model. The nonlinear parameter determined the transfer of antibody from the intravascular to a processor compartment, primarily the liver. This transfer was a function of the number of free receptors in the processor. Model simulated curves for the time course of concentration of antibody in the blood for different amounts of injected antibody revealed that blood clearance of radiolabeled antibody was profoundly decreased by increased amount of injected antibody. This model provides an explanation for the observations that tumor imaging is improved with injection of larger amounts of antibody, and a basis for modifying the pharmacokinetic behavior of an antibody in order to optimize radioimmunodiagnosis and radioimmunotherapy.

Antibodies, Monoclonal↗
PubMed1986

Comparison of low- and medium-energy collimators for SPECT imaging with iodine-123-labeled antibodies.

The planar and single photon emission computed tomography (SPECT) imaging performance of two low-energy and one medium-energy collimators has been compared for 123I(p,5n). Septal penetration in the low-energy collimators affected the planar uniformity and sensitivity and made the usual uniformity correction methods inappropriate. SPECT uniformity and resolution were also distorted by these artifacts induced in the planar images obtained with the low-energy collimators. The planar and SPECT images of a SPECT phantom contradicted the spatial resolution measurements made with a line source in air. The medium-energy collimator is recommended for imaging 123I(p,5n)-labeled antibodies in patients, particularly when quantitation is required.

Antibodies↗
PubMed1986

Effect of region of interest selection on first-pass radionuclide cardiac output determination.

In principle, region of interest (ROI) selection should not affect the measurement of cardiac output by the first-pass technique with a radioactive intravascular indicator. Clinical application of the method requires that this theoretical hypothesis be tested. Sixty-eight left anterior oblique first-pass studies were acquired with a scintillation camera and computer using red blood cells labeled in vitro with 99mTc. Calculated mean cardiac output varied in the following order with respect to ROI: lung greater than right heart greater than left ventricle greater than whole heart (both ventricles) greater than aorta. Similar variations were observed in patients both with and without valvular regurgitation. Regions of interest over left ventricle or whole heart yielded the best correlations with cardiac output by thermodilution (r = 0.96, 0.95, respectively, n = 28) as well as the smallest interobserver variations (r = 0.994, 0.995, respectively, n = 33). First-pass studies with [99mTc]red blood cells labeled in vitro can yield accurate, reproducible determinations of cardiac output provided that the effect of ROI selection is recognized and that regions are properly selected.

Adolescent↗
PubMed1985

Requirements for a treatment planning system for radioimmunotherapy.

Cancer-seeking antibodies carrying radionuclides can, in theory, be very powerful agents for the radiotherapy of cancer. However, as with all radiotherapy, the undesired dose to critical normal organs is the limiting factor that determines success or failure. The distribution of radiation dose in cancer and noncancer tissue is highly dependent on choices the therapist can make: choices of the antigens to be targeted, choices of the antibodies or antibody fragments to be used, choices of radionuclides, of amounts, of timing, and other electives. New technologies, especially of monoclonal antibody production, make the options myriad. Optimization of this therapy depends on a foreknowledge of the radiation dose distributions to be expected. The necessary data can be acquired by established tracer techniques, in individual patients, for particular treatment selections. These tracer techniques can now be implemented by advanced equipment for quantitative, tomographic radionuclide imaging and strengthened by dynamic modeling of the physiological parameters which govern radionuclide distribution, and hence radiation dose distribution.

Animals↗
PubMed1985

Videodensitometric quantitation of stenosis: in vitro and in vivo validation.

Percentage of stenosis of a vascular lumen was quantitated using a digital subtraction angiography system with videodensitometric analysis. To validate the algorithm and methods, we used precisely drilled Lucite rods of three inner diameters and various reduced diameters to give known luminal reduction. Both in vitro and in vivo results of stenosis measurements resulted in an excellent correlation between actual and measured values (correlation coefficient greater than 0.9 for all trials). Consistent underestimation of stenosis of about 5% was attributed to the various image degradations inherent with the imaging procedure and equipment. Errors were greatest with midrange stenoses and less at the extremes of the lesion values. An insufficient signal-to-noise ratio was caused by low photon flux and/or low contrast material concentration and overlying vasculature filled with contrast material. Overall, the videodensitometric technique is accurate, easy to implement, objective, and relatively free of errors associated with the geometric/edge detection method.

Absorptiometry, Photon↗
PubMed1981

The value of radionuclide scintigraphy in patients with non-visualized gallbladders by oral cholecystography.

This study evaluated the clinical usefulness of Tc-99m-PyG cholescintigraphy in patients who had nonvisualization of the gallbladder after OCG. Nineteen patients with non-visualized gallbladder with OCG subsequently had Tc-99m-PyG cholescintigraphy performed. In nine patients the gallbladder visualized, whereas in ten it did not. Statistical analysis of this limited number of patients showed that Tc-99m-PyG cholescintigraphy was able to separate those patients with clinically significant gallbladder disease from those patients without significant gallbladder disease (p less than 0.05).

Cholecystography↗
PubMed1980

Immediate renal imaging and renography with 99mTc methylene diphosphonate to assess renal blood flow, excretory function, and anatomy.

99mTc methylene diphosphonate (99mTc MDP) was evaluated as a clinical renal imaging agent in 20 patients referred for bone scintigraphy. Sequential scintigraphy, which was started immediately after injection, yielded blood flow studies of high quality, and subsequent images accurately delineated renal anatomy and excretion in nonazotemic patients. In comparison with delayed images, early images were vastly superior in quality and demonstrated improved target-to-nontarget activity ratios(p less than 0.001) and improved lesion detectability (p less than 0.01). Renal imaging performed incidental to bone scintigraphy with MDP can be greatly enhanced by initiating sequential scintigraphy immediately after injection.

Adolescent↗
PubMed1978

Quantitative hepatic scintiangiography.

A new method has been developed which quantitatively assesses the relative arterial and portal venous blood flow in both normal and diseased liver tissue. Using a standard dedicated computer and routine clinical programs, the hepatic blood flow time/activity curve was analyzed. Specific indices were calculated: alpha1 represents aortic blood flow; alpha2, portal blood flow; alpha1/alpha2, the ratio of arterial to portal blood flow; and delta T, the difference in time between the peak of the arterial curve and the junction of the arterial and portal phases of the hepatic curve. Student's t-tests showed that these indices may be used to differentiate between the normal population and patients who have metastases or moderate to severe hepatocellular disease. Patients with early hepatocellular disease could not be differentiated from the normal population, but they could be separated from patients with more advanced hepatocellular disease. Patients with severe hepatocellular disease could not be separated from those with metastases. The most important uses of this technique may be in following a patient and determining when hepatocellular disease has become irreversible, and in following the course of treatment of a patient with metastatic disease to the liver.

Humans↗
PubMed1977

New approach to interpretation of technetium-99m pyrophosphate scintigraphy in detection of acute myocardial infarction: clinical assessment of diagnostic accuracy.

A modified classification for interpreting technetium-99m pyrophosphate scintigrams defines the 2+ diffuse pattern of tracer uptake as equlvocal rather than positive for acute myocardial infarction. Results of scintigraphy using this classification were compared with results of standard diagnostic tests for myocardial infarction in 235 patients admitted to a coronary care unit with acute chest pain. Of 81 patients with acute transmural infarction by standard clinical, electrocardiographic and serum enzyme criteria, 76 had a positive, 5 an equivocal and none a negative scintigram. Of 18 with acute nontransmural infarction by standard criteria, 7 had a positive, 9 an equivocal and 2 a negative scintigram. This it was uncommon for a patient with acute myocardial infarction, transmural or nontransmural, to have a definitely negative technetium-99m pyrophosphate study. Ten patients had equivocal evidence of infarction by standard criteria. Of the remaining 126 patients with no evidence of acute myocardial infarction by standard criteria, 87 had a negative, 35 an equivocal and 4 a definitely positive scintigram. Thus the definitely positive scintigraphic pattern was relatively highly specific for acute myocardial infarction. If the 2+ pattern had been considered positive, the specificity of the technique would have been greatly decreased. Computer processing strengthened observer certainty of the visual impression but changed the scintigraphic evaluation in only eight cases. Thus, use of an equivocal pattern renders technetium-99m pyrophosphate imaging both an extremely sensitive and specific method for detecting acute myocardial infarction.

Acute Disease↗
PubMed1977

Fate and distribution of inhaled nitrogen dioxide in rhesus monkeys.

The intra- and extrapulmonary distributions of inspired nitrogen dioxide (NO2) were studied by exposing rhesus monkeys to air mixtures containing concentrations slightly greater than ambient (0.56 to 1.71 mg per m3, or 0.30 to 0.91 ppm) of NO2 labeled with tracer quantities of NO2 containing nitrogen-13 dioxide (13NO2). The 13NO2 (half-time, 10 min) was synthesized by the oxygen-16 (P, alpha)13N nuclear reaction in an isochronous cyclotron. The intrapulmonary location and concentration of the inspired 13NO2 was detected continuously by external monitoring of the annihilation radiation consequent to positron emissions from disintegrating 13N. The 13N concentration of arterial blood was also measured at intervals, and the blood values were correlated with those from the lung. Chemical measurements of NO2 concentration in inspired and expired air were performed by the Saltman method. Control studies were performed with xenon-125 (125Xe) (halftime, 17 hours). The results demonstrated that 50 to 60% of the inspired pollutant was retained by the primate during quiet respiration; the gas was distributed throughout the lungs. Once absorbed, NO2 or chemical intermediates remained within the lungs for prolonged periods after cessation of exposure, and dissemination of the pollutant or its derivatives to extrapulmonary sites occurred via the blood stream. Indirect evidence indicated the probable reaction of NO2 with water in the nasopharynx and lungs to form nitric and nitrous acids. The reaction of these acids with pulmonary and extrapulmonary tissues probably accounts for the biologic toxicity of NO2.

Animals↗
PubMed1975

Production and characteristics of 125Xe: a new noble gas for in vivo studies.

Radionuclides of the noble gases are extensively used to assess ventilation and blood flow in clinical and investigative studies. Xenon-133 is most commonly used but is not optimal for these in vivo studies. Xenon-125 has better physical characteristics and can be produced with a cyclotron by a 127I(p,3n)125Xe reaction; this reaction results in a maximum of 25 mCi/gm/cm2/muA-hr for 31-MeV protons. Under actual production conditions, 11 mCi/muA-hr were collected. Xenon-125 decays by electron capture with a 17.2-hr half-life and contributes less radiation per dose of radioactivity than 133Xe. The radiation dose to the lungs from 133Xe and 125Xe is 5.0 and 1.8 mrads/mCi-min, respectively. The radiation dose per usable photon for 125Xe is only 0.3 of 133Xe. The principal photons of 125Xe, 188 keV (55%) and 243 keV (29%), are more intense and are in an energy range that is more advantageous for imaging than the 81 keV (35%) of 133Xe. These physical properties of 125Xe result in better spatial resolution at the same information density and with less radioactivity administered to the patient. Phantom studies showed that 12.7-, 9.5-, and 6.4-mm lead bars were resolved with 125Xe using a 410- keV diverging collimator wheras only the 12.7- and 9.k-mm lead bars were resolved using 133Xe and either a 410-keV or 140keV diverging collimator.

Krypton↗
PubMedDate not supplied

The beneficial effects of short pulse width acquisition and ECG-gating in digital angiocardiography.

Experimental intravenous left ventriculography and coronary angiography after aortic root injection were performed in 13 animals. Various image acquisition and digital image processing techniques were employed. These included single mask mode subtraction, integrated mask mode subtraction, ECG-gated image acquisition, TV camera read-out in interlaced mode, and pulse progressive read-out with 1- to 5-ms pulse width. High quality images were obtained consistently only after ECG-gating and use of 1- to 5-ms pulse width with pulse progressive read-out of the TV camera. Integration of four to eight background as well as contrast images all from the same phase of the cardiac cycle further improved image quality.

Angiocardiography↗
PubMedDate not supplied

Interlaced versus progressive readout of television cameras for digital radiographic acquisitions.

A comparison was made of two methods for reading the TV camera target for digital radiographic acquisition, interlaced and progressive readout. Experiments were performed with a plumbicon TV camera to measure x-ray exposure requirements and resolution capabilities after readout for the two modes. Real time digital (30 frames per second, 256(2) matrix) and single-frame electrocardiogram gated images of the contrast-filled coronary arteries in a dog were acquired with both formats. Results demonstrate a reduction in patient exposure of up to four times for single-frame progressive readout images over interlaced acquisition for static images of comparable quality. Imaging of rapid motion objects (e.g., coronary arteries) with interlaced TV scanning results in "scalloping" of edges and resolution degradation. The short pulse width capability of progressive readout eliminates motion blurring and preserves object detail. Progressive readout is the preferred mode of TV camera readout for most digital radiographic applications due to more flexible x-ray techniques, superior images, and total utilization of the input x-ray flux for lower patient exposure.

Angiography↗