[en] A study was carried out to investigate the use of a gamma camera for quantitative measurement of the absolute radioactivity in internal organs. Phantoms simulating different patient conditions were used to derive the attenuation correction factor and the conversion factor which relates a known radioactive dose to organ activity. The delimitation of the source image was established by means of an isocontour of maximum count rate. A mathematical approach was used for achievement of isosensitivity with depth of the organ and for correction for background. The accuracy of the procedure was proven by the recovery over the stomach area of the ingested activity. The method is applied to the quantitative assessment of the splenic red-cell volume. (orig.)

No abstract available

[en] Published in summary form only

[en] The iron uptake in bone marrow and spleen was measured in 29 patients with myelofibrosis using ⁵²Fe and quantitative scanning. In 10 patients, no iron uptake in the marrow could be observed and active erythropoiesis was extramedullary only. In the bone marrow of patients with myelofibrosis, the iron uptake per nucleated red cell was less than that observed in conditions without myelofibrosis or extramedullary erythropoiesis. Increasing splenic iron uptake was likely to be associated with a decreasing bone marrow iron uptake and was related to the size of the spleen. The data suggest that in myelofibrosis, the spleen dominates iron uptake through intense erythropoiesis and a high splenic blood flow, thus restraining iron supply to the bone marrow. (author)

[en] This prospective study was designed to evaluate the diagnostic performance of ^99mTc-sestamibi exercise gated planar myocardial imaging by comparison with both visual and quantitative analyses of SPET. The study was conducted in 115 consecutive patients with known or suspected CAD, including 54 patients with a previous myocardial infarction (MI), referred for exercise testing prior to coronary angiography. Multi-gated planar imaging and SPET were performed after bicycle exercise. The end-diastolic (ED) and SPET images were visually scored (SVi). Myocardial uptake was quantitated on SPET slices using maximum count circumferential profiles (SQu) and defect extent was measured by comparison with gender-matched data sets obtained from 27 controls (<5% likelihood of CAD). CAD was defined as coronary artery stenosis >50% and/or regional wall motion abnormality. The cut-off criteria for positivity of the three procedures were determined from receiver operating characteristic (ROC) curves derived from the data of patients without previous MI. The area under the ROC curves was similar for ED, SVi and SQu. This was confirmed by the analysis of sensitivity performed using the ROC curve-derived cut-off criteria, in patients with or without previous MI. SVi was more sensitive than ED in identifying the diseased vessel(s) (ED: 41% vs SVi: 80%); but ED was more specific in this respect (ED: 79% vs SVi: 61%). (orig.)