Calculation of the radiation dose at a bone-to-marrow interface.
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Algorithms↗
Biomedical subjects
A van Lingen
Publications and source records attributed to A van Lingen.
Tumour localisation with 131I-labelled human IgM monoclonal antibody 16.88 in advanced colorectal cancer patients.
Human IgM monoclonal antibody 16.88 recognised an intracellular antigen strongly expressed in colorectal cancer tissue in 51% of our patients. Tumour localisation was carried out with 185 MBq 131I-16.88 (8 mg) in 20 of these patients with advanced disease. In 16 patients (80%) immunoscintigraphy was positive in at least one organ site with disease. Of all sites, 55% could be visualized. In general, lesions less than 3 cm could not be detected. Sequential immunoscintigrams of liver metastases showed variable patterns. Initial "cold" lesions corresponded to liver metastases with poor blood supply as indicated by 99mTc-sulphur-colloid and 99mTc-HMPAO scintigraphy, respectively. The mean (S.D.) biological half-life (whole body clearance of radioactivity) was 37.6 (5.0) h. A second infusion of 131I-16.88 with the addition of high doses of unlabelled 16.88 could be done safely, but did not result in better visualisation of tumour lesions or affect radioactivity clearance from the body.
Adult↗
Qualitative and quantitative kinetics of submucosally administered antibody fragments in patients with rectal carcinoma: the detection of lymph node metastasis in relation to local tracer diffusion.
Immunoscintigraphy after submucosal administration of a mixture of 131I-anti-CEA and 131I-anti-CA-19-9 around the tumor in patients with rectal carcinoma may improve pre-operative staging and may contribute to the selection of patients eligible for local treatment. However, visual discrimination of local lymph node metastasis appears unreliable, partly because of scatter from the injection site and substantial diffusion of the radiotracer into the interstitium. Analysis of the diffusion profile, however, may improve the sensitivity and accuracy of this immunoscintigraphic approach.
Aged↗
Analysis of time-activity curves related to myocardial metabolism. The case of 123I-heptadecanoic acid.
Time-activity curves are frequently used in the external assessment of the kinetics of radiolabelled non-esterified fatty acids. Analysis of time-activity curves is accomplished by fitting an analytical curve through the data points of the time-activity curve, resulting in two or more parameters of the curve fit. Before interpreting the results of curve fitting, the precision of each of the parameters has to be determined. In the present study the precision of the parameters of monoexponential plus constant curve fit of time-activity curves after administration of 123I-heptadecanoic acid was assessed for an acquisition time of 75 min. Two parameters were used, the T1/2 of the monoexponential and the ratio A/A+C, where A is the amplitude of the monoexponential and C the constant. A model study was used to assess the precision of the parameters of curve fitting. The precision of the parameters was calculated for wide ranges of the T1/2 (0-60 min), A/A+C (0-100%) and the noise content of the time-activity curve. The results are presented as the 10th and 90th percentiles.
Animals↗
Serial radionuclide determinations of graft perfusion in pancreas transplantation.
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Adult↗
Comparison of 17-iodine-131 heptadecanoic acid kinetics from externally measured time-activity curves and from serial myocardial biopsies in an open-chest canine model.
The relation between the externally measured myocardial time-activity curve and the radiochemically determined kinetics of iodine-131(131I) heptadecanoic acid was studied in an open-chest canine model under different metabolic interventions. Kinetics were assessed by analysis of 12 biopsies taken in an assay period of 90 min. Time-activity curves were fitted with a monoexponential plus constant. The halftime value of the exponential of the external curve corresponded well with the elimination rate of 131I from the myocardium: 14.6 +/- 4.5 min vs. 14.6 +/- 5.3 min. The constant was build up of three components: free 131I in cardiac tissue, the almost constant activity of the radiolabeled free fatty acid (FFA) in the myocardial lipid pool, and the radioactivity of blood and noncardiac tissues. The contribution of blood and noncardiac tissue to the constant amounted to a mean value of 77%. These findings support the analysis of externally measured time-activity curves with a monoexponential plus constant curve fit, in which background correction is not necessary. In cases where lipid storage is predominantly present, high T1/2 values, both internally and externally, were found, which were fitted with a monoexponential curve. It can be concluded that externally measured time-activity curves reflect satisfactorily the kinetics of radioiodinated heptadecanoic acid.
Animals↗
Quantitative radio-isotope cisternography for the investigation of CSF circulation in the posterior fossa and basal cisterns--a preliminary report.
In the absence of hydrocephalus there is an inclination to overlook enlargement of CSF spaces. In theory such enlargement might be the pathological basis for unexplained diseases seemingly related to disorders in CSF dynamics. By using Indium-111-DTPA in scinti-cisternography for 66 hours an attempt was made to identify such disorders by quantification of CSF circulation in the posterior fossa. The experimental data were fitted by means of two successive least square logarithmic regression analyses in order to make possible differentiation between "known" CSF disturbances and "external hydrocephalus". Theoretically, a biexponential curve would be expected. If therefore a monoexponential "best fit" is found, disturbances of CSF circulation may be taken to be present. For a definition of the features of normality in the case of a biexponential curve, however, further data on normal volunteers are needed.
Cerebrospinal Fluid↗
The elimination rate of 123I-heptadecanoic acid after intracoronary and intravenous administration.
When calculating the elimination rate of radioactivity after the administration of radioiodinated heptadecanoic acid (123I-HDA), background correction is necessary due to the high level of background activity. In the present study, the subtraction method of Freundlieb et al. was investigated on validity. This was done by comparing the half-time values of the elimination rate after intravenous (i.v.) and intracoronary (i.c.) injection. In the latter case, no background correction was necessary. Six patients undergoing cardiac catheterization were studied. Scintigraphy was performed after the injection of 123I-HDA into the left coronary artery and after i.v. injection. Half-time values were calculated from regions of interest drawn over myocardium perfused by the left-anterior descending branch (LAD) and the left circumflex artery (LCX). In the LAD region, the mean half-time value in the i.c. study was 22 min, while in the corrected i.v. study, the mean value was 27 min. In the LCX region, the half-time values were 24 and 33 min, respectively. The background-subtraction procedure proposed by Freundlieb et al. for i.v.-injected 123I-HDA is incomplete, as it resulted in half-time values that were higher than those of the i.c. study.
Arteries↗
Evaluation of background correction methods.
After intravenous injection of radioiodinated heptadecanoic acid a high background activity disturbs direct determination of myocardial elimination rates. Several correction procedures for background activity are used. After intracoronary administration a much lower background activity is found. To validate the background subtraction procedures we compared in this study the results of the correction procedures with the results after intracoronary injection of the fatty acid, in which no background subtraction was performed. In ten patients myocardial elimination rates after intracoronary and after intravenous injection were determined. A modified bi-exponential curve fitting procedure, assuming a constant background activity, showed the best results compared with the intracoronary study.
Background Radiation↗
Left and right ventricular function in porcine Escherichia coli sepsis.
In anesthesized pigs, hemodynamic measurements and gated bloodpool scintigraphy were performed during and after infusion of live Escherichia coli (2 X 10(8)/kg). Ejection fractions (EF) as well as the relation between end-diastolic volumes (EDV) and stroke work (SW) were used to evaluate changes in left (LV) and right ventricular (RV) function. Porcine E. coli sepsis proved to be characterized by pulmonary vascular hypertension (PVH) and systemic arterial hypotension, accompanied by a reflex increase in heart rate. Systemic flow remained essentially unchanged. E. coli infusion resulted in pronounced and opposite changes in LV and RV preload. RVEDV increased initially and then returned to the value observed before E. coli infusion. LVEDV showed a continuous decrease during the observation of 3 hours. Alterations in LVSW and RVSW appeared to parallel the changes in LVEDV and RVEDV. No significant changes in LVEF and RVEF were found. It is concluded that porcine E. coli sepsis might be a suitable model for human sepsis complicated by PVH. In this animal model no clear signs of myocardial depression or evidence of right heart failure were observed.
Animals↗
Short-lived 195mAu for evaluation of left ventricular function by first-pass radionuclide angiography.
In 52 patients with coronary artery disease the feasibility of performing first-pass cardiac studies with the short-lived tracer 195mAu was tested. Even with a currently available gamma camera, good results were obtained in terms of imaging quality, reproducibility and exercise response. The use of a multicrystal camera would, however, be desirable.
Coronary Disease↗
Improved detection of viable myocardium with fluorodeoxyglucose-labeled single-photon emission computed tomography in a patient with hibernating myocardium: comparison with rest-redistribution thallium 201-labeled single-photon emission computed tomography.
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Aged↗
F18-fluorodeoxyglucose single-photon emission computed tomography predicts functional outcome of dyssynergic myocardium after surgical revascularization.
BACKGROUND: Prediction of functional recovery after revascularization is possible with positron emission tomography and F18-fluorodeoxyglucose (FDG). Recently, the use of FDG in combination with single-photon emission computed tomography (SPECT), with 511 keV collimators, has been proposed to allow more widespread use of FDG. In the current study we aimed to predict improvement of regional left ventricular function after surgical revascularization with FDG and SPECT. METHODS AND RESULTS: Twenty-seven patients with regional wall motion abnormalities (on echocardiography) underwent early thallium-201 (Tl-201) SPECT to assess perfusion and FDG SPECT to assess regional glucose uptake. The left ventricular myocardium was divided into 13 segments. For each segment, tracer uptake was evaluated visually (with the use of a 4-point scoring system) by consensus of two observers. Myocardial viability was determined in dyssynergic segments on echocardiography and defined as normal perfusion or increased FDG uptake in a perfusion defect (mismatch). Absence of viability was defined as a perfusion defect without increased FDG uptake (match). Improvement of regional wall motion was assessed 3 months after revascularization. In the group of segments that were viable on FDG/Tl-201 SPECT (n = 64), the segmental wall motion score decreased from 1.4 +/- 0.5 to 0.6 +/- 0.7 (p < 0.01), whereas the segmental wall motion score remained unchanged in nonviable segments (n = 72): 1.6 +/- 0.5 versus 1.5 +/- 0.6 (not significant). Forty-six (72%) of the 64 segments that were viable on FDG/Tl-201 SPECT demonstrated improved contractile function after coronary revascularization. In contrast, only 7 (10%) of 72 nonviable segments on FDG/Tl-201 SPECT showed improvement in function after revascularization (p < 0.01 versus viable segments). The sensitivity, specificity, and positive and negative predictive values were 87%, 78%, 72%, and 90%, respectively. CONCLUSION: This study shows that FDG/Tl-201 SPECT can identify patients who improve in regional ventricular function after revascularization.
Aged↗
Distribution and kinetics of 131I-labeled human IgM monoclonal antibody 16.88 in patients with advanced colorectal cancer.
Sequential immunoscintigrams were used to describe the relative distribution and kinetics of 8 mg 131I-labeled human IgM monoclonal antibody 16.88 in 20 patients with colorectal cancer. The results show that the initial activity was higher and the clearance rate was faster (P < 0.05) from the left ventricle and liver than from most organs. In bone marrow the reverse was observed (P < 0.05). The biological half-life of 131I(-16.88) in tumor tissue (range 35.4-47.5 h) was longer (P < 0.01) than that in normal tissue (30.2-41.9 h). The image contrast ratio between liver metastases and background increased from 0.8 to 1.3 and for lesions outside the liver from 1.1 to 1.6. The estimated effective dose equivalent was 0.12 mSv/MBq. A second infusion 2 weeks after the first with the addition of unlabeled 16.88 up to 1000 mg for improvement of tumor tissue uptake was not of clinical relevance.
Antibodies, Monoclonal↗