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M L Goris

Publications and source records attributed to M L Goris.

At least 19 recordsLinked to original sources
PubMed1992

Overview of animal studies comparing radioimmunotherapy with dose equivalent external beam irradiation.

As the field of radioimmunotherapy (RIT) continues to develop and looks increasingly promising, there is growing interest in the radiobiology of RIT. Recently, several investigators have conducted studies in animal models comparing the relative efficacy of RIT with dose equivalent external beam irradiation. Although these studies are the first of many to follow, the results are provocative and several patterns are suggested by the available data. The results of the studies are summarized and compared, and preliminary hypotheses that might explain the reported observations are discussed. In summary, results from studies comparing the efficacy of RIT with external beam irradiation have been variable and may be indicative of different underlying mechanisms. While the particular experimental model, design and methodology used to compare the efficacy of RIT with external beam irradiation are probably important influences upon subsequent observations, it appears that for a given tumor type, the size of the survival curve shoulder or alpha/beta ratio, and tumor doubling time are important determinants of the magnitude of the dose rate effect. When this effect is minimal, it is possible that other factors such as reoxygenation, the arrest of cells in G2, and selective targeting of tumor by radiolabelled antibody may explain, in part, the increased efficacy of RIT compared with external beam irradiation that has been observed in some systems.

Animals↗
PubMed1992

The effect of unlabelled monoclonal antibody (mAb) on the biodistribution of 131I-anti-idiotype mAb in murine B cell lymphoma.

The 38C13 murine B cell lymphoma model was used to study the effect of the preinjection of unlabelled anti-idiotype monoclonal antibody (mAb) on the subsequent biodistribution of 131I-anti-idiotype mAb. Mice with established tumors received 0-500 micrograms of unlabelled anti-idiotype mAb 24 h prior to the administration of 131I-anti-idiotype (specific), or both 125I-anti-idiotype and 131I-isotype-matched irrelevant control (nonspecific) mAb. Mice were counted daily in a gamma counter and sacrificed at 2-144 h following injection. Mice were dissected and the weight and activity of the animals and organs were measured. Mice were bled periodically and circulating idiotype levels were measured using an ELISA assay. Five hundred micrograms of unlabelled anti-idiotype mAb increased the retention time of the specific but not the nonspecific mAb in all organs and tumor. Following pretreatment with unlabelled mAb, the cumulative tumor/whole body and tumor/normal organ ratios became similar to those of the nonspecific mAb, with concentration ratios (specific/nonspecific mAb) of approximately 1, which persisted until 96 h post injection when circulating idiotype reappears in antigen excess. In the absence of unlabelled mAb there was less retention in tumor and normal tissue. This is presumed to be due in part to decreased levels of circulating 131I-mAb secondary to rapid plasma clearance of antigen-antibody complexes and tumor cell mediated dehalogenation, which results when the specific mAb specifically binds the targeted antigen. Thus, the addition of unlabelled mAb increased the retention by decreasing the specific behavior of the anti-idiotypic antibody.

Animals↗
PubMed1992

Parathyroid imaging. Use of dual isotope scintigraphy for the localization of adenomas before surgery.

Seventy-nine patients with primary hyperparathyroidism, whose average preoperative blood calcium level was 11.6 mg/dl, underwent thallium-technetium dual isotope scintigraphy of the thyroid and parathyroids. For patients who had surgery, the detection and localization rate of parathyroid disease or the sensitivity was low (0.53), but the positive predictive value for the location was high (0.80). Correct localization correlated positively with the weight of the tumor but not significantly with the parathyroid hormone blood level nor with the blood calcium level. Unprocessed data alone were sufficient to predict correctly the location in two thirds of the detected cases. Computer processing increased the sensitivity without decreasing the specificity. Those results, at variance with earlier published data but congruent with another more recent study, require a reevaluation of the role of this scintigraphic technique in the management of hyperparathyroidal patients.

Adenoma↗
PubMed1991

Long-term scintigraphic appearance of extremities following bone tumor resection and allograft reconstruction.

The authors retrospectively reviewed the Tc-99m medronate scan findings in six patients who had no evidence of metastatic disease following en bloc resection of a primary osteosarcoma and subsequent limb reconstruction using allograft bone. Persistently increased radionuclide uptake was noted at the junction between the host bone and the graft, while the graft cortical bone showed persistently decreased activity. Radionuclide uptake at the periphery of the graft varied. Over time the youngest patient in the series had increasingly normal scan findings.

Adolescent↗
PubMed1991

Parathyroid imaging.

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Costs and Cost Analysis↗
PubMed1991

The quantification of planar scintigraphy using three dimensional modelling of organ shadows.

A method to define biodistribution from planar scintigraphic data is presented. Sampling regions or regions of interest (ROI's) are first defined as the projection contour of organs. From anatomical knowledge the three dimensional volume of the organ whose shadow has been traced is reconstructed. When the relevant organ volumes including the whole body or relevant whole body part have been defined, the count rate density in each pixel is assumed to represent the sum of the product of the projecting organ partial volumes times the tracer concentrations in the underlying organs. The solution (the definition of organ concentrations) is found by a matrix inversion. Validation is obtained in two ways. The first method is illustrative: an image is reconstructed from the defined volumes modulated by the computed concentrations. This image, if the method is correct, should be a crisp equivalent of the original data and closely similar to it following blurring with a convolution kernel equal to the imaging system's point spread function. The second is analytical: from reconstructed S.P.E.C.T. data in which voxel values are directly proportional to organ concentrations, a planar image is reconstructed. Organ average voxel values are computed in the S.P.E.C.T. image with volumetric ROI's and in the reprojected planar image using the method described here. The methods should yield the same concentration data but for a scaling factor. The method has the advantage that it yields volumetric and concentration data which are directly applicable to MIRD type analysis. In effect, the standard man assumptions in MIRD analysis have been incorporated in the calculation of the concentrations.

Humans↗
PubMed1979

Reliability and reproducibility of interpretation of 99mtechnetium pyrophosphate myocardial scintigrams.

The interpretations of 156 99mtechnetium pyrophosphate myocardial scintigrams by four observers were analyzed in order to determine the reliability and reproducibility of the subjective process of reading scintigrams. The scintigrams were scored on an integral scale from 0 to 4, depending upon the degree of myocardial radionuclide accumulation, and the site and nature of uptake were specified. Exact agreement upon score was generally poor but approximate concurrence of interpretation was good (90.4 and 92.5% inter- and intra-observer agreement, respectively). There was somewhat less agreement on scintigrams with the higher scores of 3 and 4 (83.3 and 78.0%, respectively). A high level of concurrence upon the differentiation between diffuse and localized uptake, and upon the site of uptake, was found. We conclude that only approximate rather than exact agreement of individual readers' interpretations can be expected in this subjective technique, that scintigrams with higher degrees of radionuclide accumulation produce slightly greater observer disagreement, and that variability of interpretation could account for some of the diagnostic inaccuracy of 99mtechnetium pyrophosphate myocardial scintigraphy.

Angina Pectoris↗
PubMed1979

Cardiac damage produced by direct current countershock applied to the heart.

This study examined the pathophysiology of the myocaridal damage produced by direct current shock over a dose range of 10 to 90 watt-seconds, applied directly to the heart in 26 dosgs. The extent of injury produced was assessed with creatine kinase depletion and light and electron microscopy, and was correlated with in vivo imaging and tissue distributions of the isotopes technetium-99m pyrophosphate and thallium-201. Changes in intramyocardial temperature and regional myocardial blood flow were also measured. Uptake of technetium-99m pyrophosphate occurred exponentially with graded increases in shocks, and this agent was more sensitive than thallium-201 in detecting injury both on imaging and at tissue level. The threshold for significant injury was approximately 30 watt-seconds, and on electron microscopy a characteristic feature was marked dehiscence of the intercalated disks between the damaged myocytes. The use of different-size paddles did not appear to affect the total number of cells damaged. However, with large paddles the injury was more superficial and spread over a wider area. With short time intervals between successive shocks, a greater amount of injury occurred, in part because of a compounding of the thermal component of the damage. Hypothermia can reduce the degree of injury.

Animals↗
PubMed1979

Pyrophosphate retention by previously irradiated renal tissue.

In 3 patients, each of whom had previously had part of one kidney included within the field during radiation therapy, whole-body bone imaging using 99mTc-pyrophosphate showed increased activity in the irradiated renal segment. Possible mechanisms of such renal uptake are discussed.

Adolescent↗
PubMed1978

Value of 111Indium chloride bone marrow scanning in the differential diagnosis of blood count depression in lymphoma.

In patients with Hodgkin's disease or non-Hodgkin's lymphoma, the etiology of low peripheral blood counts is often difficult to determine. Often it is based on the results of a "random" bone marrow biopsy and/or aspirate, plus evaluation of circulating peripheral blood elements. However, these tests may be misleading. The present study evaluates the usefulness of 111Indium chloride bone marrow scanning in conjunction with marrow biopsies in distinguishing intrinsic from extrinsic causes for low peripheral blood counts. Thirty consecutive patients with Hodgkin's disease or non-Hodgkin's lymphoma, presenting with low peripheral blood counts and without any form of antineoplastic treatment for at least 5 weeks, were analyzed. Scan ratings were felt to be clinically accurate in 27 of the 30 patients analyzed (90%). In 18 patients (60%), the scan provided information which was not provided by any other standard test. 111Indium chloride scanning in conjunction with a marrow biopsy appears to be a useful, accurate means of evaluating bone marrow function in patients with depressed peripheral blood counts.

Adolescent↗
PubMed1978

Bone marrow regeneration following large field radiation: influence of volume, age, dose, and time.

Regeneration of bone marrow following radiation only was investigated using 111Indium as a bone scanning agent. Factors which influence local marrow regeneration are dose, age of the patient, and the total amount of the marrow which was irradiated. Time effects are not demonstrated in this study, except to the extent that most regeneration did occur within the first 12 months following irradiation. The most striking finding is the effect of the irradiation volume. Apparent inconsistencies in earlier reports concerning the dose effect could be explained by this effect alone.

Adolescent↗
PubMed1978

Intense concentration of technetium-99m pyrophosphate in the kidneys of children treated with chemotherapeutic drugs for malignant disease.

Seventeen of 265 bone scans in children receiving chemotherapy for various malignant diseases exhibited intense renal parenchymal uptake of radioactivity during bone imaging. In a retrospective analysis, it was learned that uptake occurred when imaging was performed within one week of cancer chemotherapy. It was encountered after injection of cyclophosphamide (P less than 0.05), vincristine (P less than 0.01), and doxorubicin (P less than 0.02). In this series, none of the 265 scans showed intense renal uptake unless the patient received chemotherapeutic drugs in the preceding week. This finding did not seem to result from altered renal function, and the exact cause has not been defined.

Antineoplastic Agents↗