The Journal of nuclear medicine and allied sciences最新文献

Tumor Associated Glycoprotein 72 (TAG-72) is common to most epithelial tumors. In this study serum levels of TAG-72 were measured in 36 healthy female subjects, in 94 patients with breast cancer, and in 43 others with epithelial ovarian cancer. More particularly, 27 out of the 94 patients with breast cancer had early disease (Stage I-I; or T 0-2b; N 0-1b; M 0), while the remaining 67 had advanced disease (Stage III-IV; or T 0-4; N 0-3; M 0-1). All the 43 subjects with ovarian cancer were at stage III-IV (FIGO Classification), 12 of whom had minimal disease (lesions less than 2 cm) and the other 31 had bulky disease. 3.5 U/ml being the highest value found in the control group, we arbitrarily assumed 3.85 U/ml (mean +/- 3 SD) as the cut-off limit in this preliminary study. Among the patients with breast cancer, 17 out of the 67 subjects with advanced disease (25.3%) and 1 out of the 27 others with early disease (3.7%) exceeded the TAG-72 cut-off limit. Among the patients with ovarian cancer, 2 out of the 12 subjects with minimal disease (16.7%) and 22 out of the others 31 with bulky disease (70.9%) had TAG-72 levels above cut-off limit. High TAG-72 levels were found in all the histotypes of ovarian cancer including the mucinous type. Preliminary data seem to indicate that in ovarian cancer variations in serum levels of TAG-72 are in agreement with the trend of the disease.(ABSTRACT TRUNCATED AT 250 WORDS)

We evaluated the analytical performance of two commercial RIA kits for the assay of plasma atrial natriuretic peptide (ANP), which use different antisera and tracers, in order to verify the most suitable RIA procedure for the assay of ANP in plasma samples. In particular, two different procedures for the purification of plasma were evaluated. The first one uses the extraction of plasma samples with Sep-Pack C18 cartridges and the second immunoextraction (C-terminal ANP-specific antibody bound to solid phase of Sepharose). The sensitivity and precision of the two RIA kits proved inadequate, being unable to provide an acceptably precise measurement of the plasma ANP concentrations in normal subjects. An improvement in precision and sensitivity was obtained by using "fresh" (or purified) preparations of the tracer and standard solutions, and by adding PEG to the B/F separation step. The direct assay (without preliminary purification) was not possible due to a serious overestimation of plasma levels due to the presence of interferences; on the other hand, the extraction step increased the imprecision and the complexity of the assay. Moreover, the extraction recovery of ANP added to plasma samples in the procedure using Sep-Pak cartridges is about 50-60%, while it was found to be almost complete (about 90%) in the immunoextraction procedure. Moreover, a comparison of the results obtained with the two RIA systems indicated that the antisera have comparable sensitivities, but quite different specificities; however, neither of the two RIA kits showed a completely satisfactory degree of sensitivity, precision and practicability.

99mTc-mercaptoacetyltriglycine (MAG3) has been proposed as an alternative to 131I-orthoiodohippurate (OIH) for the scintigraphic determination of effective renal plasma flow (ERPF). The purpose of this study was to compare the ERPF values determined simultaneously with MAG3 and OIH by a dual channel technique in a large group of subjects with widely ranging renal function. During the last two years, we administered a simultaneous injection of 74 MBq of MAG3 and 0.74 MBq of OIH to each subject who underwent a renal scintigraphic study in our hospital. They were 53 females and 50 males (mean age: 52 years; range: 18-70 years), either normal (30) or with a diagnosis of essential hypertension (53), chronic renal failure (14), renal calculi (5), or renal transplant (1). Plasma clearance and ERPF were calculated with both radiocompounds by using the exponential formula of Tauxe and coworkers and a single plasma concentration determination sampled 44 min after injection of the two tracers. The time-activity curves for kidney and blood were of the same bi-exponential type. The mean ratio between the two plasma clearances was 0.49. The linear regression of the ERPF values obtained with the two radiocompounds was highly significant (r = 0.69; p less than 0.0001) and is expressed by the equation: ERPF (MAG3) = 0.453 ERPF (OIH) + 25.7. These data suggest that the routine calculation of ERPF from MAG3 clearance is consistent with the results obtained from OIH clearance. In conclusion, MAG3 appears to be a good predictor of ERPF in routine clinical practice.

This study addresses the impact of background activity on the use of radioimmunoconjugates for radioimmunodiagnosis and radioimmunotherapy. Since the liver and the spleen represent organs with preferential nonspecific uptake, we exposed radiolabeled (iodinated and Indium-111 labeled) preparations of monoclonal antibodies to a suspension of fresh liver and spleen cells at physiological temperature and compared their immunoreactivity, in vivo biodistribution, and tumor targeting to those of the same radiolabeled proteins without prior adsorption to this suspension. The biodistribution studies were performed under conditions of high background activity, i.e., shortly after the injection (1 hour) and using a high dose of the protein. Preadsorption of radiolabeled monoclonal antibodies results in a significant decreased uptake in certain normal tissues, i.e., greater contrast between normal and tumor tissues, as demonstrated by the quotient of the two target-to-nontarget ratios (exposed/unexposed antibody) which was greater than one for most of the tissues examined.

Sonographic images of liver hemangioma are not specific. Causal detection imposes further investigations (angiography, CT, NMR) which are not always practicable. 99mTc-red blood cells study after 99mTc colloid liver scintigraphy has been already proposed. Ten patients with hepatic hemangiomas were evaluated by simplified, simultaneous in vivo double labelling of the reticuloendothelial system and red blood cells by means of successive i.v. injections of SnCl2, 99mTc colloid albumin and 99mTc-pertechnetate. Focal colloid defects filled with the labelled RBC were revealed in 9/10 liver hemangiomas. Angioscintigraphy showed decreased perfusion and RBC scintigraphy an increased blood volume in the focal colloid defects due to the hemangiomas.

The authors present an unusual case of thyroid neoplasia firstly diagnosed as an anaplastic carcinoma with no rise in plasma thyroglobulin (Tg) and treated with total thyroidectomy and radioiodine administration. After 18 months regional lymph node metastases were present with a rise in plasma calcitonin (Ct) (8000-14000 pg/ml); lymphectomy and external radiation were performed and histology revealed a metastasis from thyroid medullary carcinoma. After 3 years, mediastinal and right supraclavicular masses were present with a concomitant rise in plasma calcitonin (from 700 to 3400 pg/ml); all neoplastic lesions showed radioiodine uptake and plasma Tg was 8.9 ng/ml. A biopsy of the supraclavicular region was taken and 131I therapy was attempted, but the patient died after 6 months. Immunocytochemistry of the biopsy revealed the presence of a medullary carcinoma-follicular variant: the neoplastic cells were variably reacting with anti-Ct and anti Tg, and, moreover, the two antigens were sometimes observed in the same cell bodies. The metabolic pattern and the clinical course of this tumour are discussed, and the authors propose that Ct and Tg plasma levels be evaluated and a total body scan (WBS) with radioiodine be performed in all cases of medullary or poorly differentiated thyroid carcinomas.

Anti TSH-receptor antibodies (TBIAb) were measured by a radioreceptor assay in 277 patients with Graves' disease, 101 with autoimmune thyroiditis, 43 with autonomous adenoma, 15 with subacute thyroiditis, 15 with euthyroid ophthalmopathy, 155 with euthyroid multinodular goiter, 10 with amiodarone-induced hyperthyroidism and 2 with tumoral TSH hypersecretion. TBIAb were present at high titers in 74% of patients with untreated or relapsed Graves' disease and, at lower titers, in only 10% of patients who had recovered from Graves' disease, in 8% of patients with autoimmune thyroiditis and in 4% of patients with euthyroid goiter. TBIAb were absent in normal subjects as well as in the other groups studied. These findings suggest that TBIAb represent a specific marker of Graves' disease, particularly of the untreated form. Their presence in non Graves' patients may be considered expression of inactive or inhibiting antibodies.

Notwithstanding the progress in medical imaging by means of computer-based techniques, several problems still remain unsolved in this field. In particular, a unified approach for the treatment of biological complexity and variability is lacking. Moreover, perceptive and cognitive aspects of medical vision play an important role in a computational approach to medical imaging and must be carefully considered. The recent developments of Computer Vision and Artificial Intelligence suggest that such a computational approach is feasible. As a consequence, symbolic representations of the clinical information contained in the images as well as adequate processing techniques are necessary. In this way the treatment of uncertainty and the qualitative analysis are made possible. Moreover, due to the intrinsic homogeneity of symbolic representations, the comparison of different image sources, signals and clinical data is attainable. In the paper, the basic principles of Computer Vision are summarized and the need of a specific computational theory for medical vision is emphasized. Afterwards, the main characteristics of integrated systems for computational imaging in medicine, are described. Some examples relative to the imaging of the cardiovascular system are also given. Although the development of artificial vision systems in biomedicine is still an area of research, very promising perspectives are opened by a computational approach.

An immunoradiometric assay for monoclonal antibodies (MoAb) recognizing gangliosides as antigens (Ag) is described and exemplified by the determination of the immunoreactive fraction of 125I-radiolabeled monoclonal A2B5 and 3G5 IgM antibodies. The assay was performed in 96-well microtiter plates equipped with cellulose filter membranes, using the antigens extracted from cloned rat insulinoma cells (RINm5F). The selectivity of the assay was demonstrated by studying the interactions of A2B5 and 3G5 with specific Ag and irrelevant gangliosides. The binding of 125I-A2B5 and 125I-3G5 to the RINm5F extract containing Ag exceeded 35% of the total applied radioactivity and depended on the degree of protein damage caused by radiolabeling, whereas irrelevant glycolipids bound 0.4% (s.d. 0.3%) of total applied 125I-3G5 and 1.2% (s.d. 0.3%) of 125I-A2B5 regardless of the initial amount of the radiolabeled MoAb used. Additional support for the specificity of this method was acquired in experiments with the A1D2 IgG antibody that interacts with a glycoprotein expressed by RINm5F cells but not with the gangliosidic antigens present in the same cell line. 125I-A1D2 bound neither Ag (0.47%; s.d. 0.12%) nor brain extracts containing irrelevant gangliosides (0.32%; s.d. 0.17%). The data for the specific MoAb-Ag systems were analyzed using a modified Lineweaver-Burk graph. By plotting the reciprocal of the fraction of specifically bound MoAb versus the reciprocal of the antigen concentration, the immunoreactive fraction was determined. The present method is rapid, convenient, and independent of variability in antigen expression on the cell surface.