Planar Scintigrams Research Articles

Difference quantitation of planar and tomographic heart scintigrams with identification of segments using reconstructive three-dimensional reference modelling.

A patient-specific three-dimensional rotational ellipsoidal shell was reconstructed from planar myocardial scintigrams. This model was homogeneously filled with radioactivity ('ideal') and then projected onto the same planes as the actual scintigrams, including the absorption of heart and background. After normalization and inhomogeneous background correction, the actual and 'ideal' images were compared in order to quantify the myocardial, ischemic and infarcted volumes (difference quantitation). 201Tl defects appeared as hot spots. The a priori three-dimensional model was cut into 14 segments by six planes. Tomographic sectional views in any desired plane made possible the identification of the 14 spatial myocardial segments on slice images for difference quantitation. The orientation of the long axis of the left heart responsible for different inseparable overprojections of segments was accounted for. The mathematics of segmentation and reconstructive three-dimensional modelling is described. Computed examples are given. A total of 624 201Tl scintigrams from 78 patients were analysed according to this method. The results obtained for the myocardial, ischemic and infarcted volumes, the orientation of the left heart's axis in the thorax and the identification of spatial myocardial segments on projected and tomographic images, as well as the global myocardial and background kinetics of 201Tl are discussed. The procedure of reference modelling and difference quantitation might also be useful in other imaging modalities, such as emission-computed tomography, single-photon emission computed tomography, computed tomography or nuclear magnetic resonance.

Immunoscintigraphy and SPECT in Patients with Pancreatic Carcinom

Encouraged by reports on immunoscintigraphy of colorectal carcinomas and by the results of our own immunohistochemical and immunoscintigraphic studies in nude mice with transplanted pancreatic carcinoma, we studied the diagnostic potential of immunoscintigraphy with a cocktail of 131I-labeled monoclonal antibodies against the tumor markers CA 19-9 and CEA in 21 patients with pancreatic cancer disease. The results were compared with those of 10 patients suffering from colorectal tumors, 2 cases with bile duct carcinoma and 1 with gastric cancer. Planar scintigraphy with 2-4 views was done repeatedly within 6 days after i.v infusion of 2 mCi of the antibody cocktail. SPECT was performed 3-4 days p.i., recently at 1 or 2 days, too. Primary tumors and metastases in the upper abdominal parts were more difficult to detect and to localise in comparison to colorectal cancer in the lower parts of the abdomen, because of relatively high tracer accumulation in kidneys, liver and spleen. Tumor enhancement in planar scintigrams was, in most cases, not recognized prior to 5 or 6 days p.i., but by SPECT 3 days p.i. or even earlier. Localisation and topographic determination were much easier and more frequent with SPECT, so that tumor detection became more reliable and sensitive. Large tumors could be detected in some cases without tumor marker concentrations in serum being elevated. Immunoscintigraphy of pancreatic carcinomas and of other cancer manifestations in the upper abdomen up to now seems to be of limited diagnostic value, the techniques involved need to be improved.

Comparison of planar and tomographic thallium-201 scintigrams following coronary vasodilatation with dipyridamole

Comparison of planar and tomographic thallium-201 scintigrams following coronary vasodilatation with dipyridamole