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Se presenta un estudio experimental que tiene por objetivo evaluar la sensibilidad y especificidad de la detección de solución de continuidad del tracto gastrointestinal con la utilización de partículas pesadas marcadas con Tecnecio 99. Se diseñó un estudio experimental prospectivo triple ciego, con un cálculo de tamaño de muestra teniendo en cuenta una sensibilidad y especificidad superiores al 95%, con un error alfa del 0.05 y una precisión de 0.05. Inicialmente se evaluaron 4 conejos de la raza Nueva Zelanda para determinar: el anestésico y la dosis a utilizar, la capacidad del estómago en mililitros; los tiempos promedios de tránsito gastrointestinal, la capacidad de la cavidad abdominal en mililitros y la biodistribución del radiofármaco (absorción gastrointestinal, diseminación y distribución hemática y eliminación renal). Se utilizaron 40 conejos de la raza Nueva Zelanda y se analizaron en tres estaciones de trabajo independientes, asignando aleatoriamente 20 conejos en cada grupo de estudio (perforados y no perforados). El radiofármaco utilizado fue Tecnecio 99 sulfuro coloidal > 100 nm, 2.5 mCi a 140 -Kev de energía preparado en una dilución de solución salina al 0.9% quedando una concentración de 0.0025 mCi por mililitro. El rastreo se realizó con una sonda gamma a 10X. El análisis estadístico se realizó con el programa Episet V:1 aplicando la prueba de Chi Cuadrado. Todos los 20 conejos que tenían disrupción del estómago, presentaron una prueba positiva para detección de radioactividad en el líquido peritoneal analizado con un valor promedio de 467 y un rango de 37 a 1748. En los 20 conejos restantes que no tenían perforación de la pared gástrica la prueba fue negativa. La sensibilidad de la metodología diagnóstica fue de 0.98 y la especificidad de 0.98 con un intervalo de confianza de 0.92-1.0. El análisis comparativo del líquido peritoneal con la sonda Gamma en los grupos dio un valor de Chi Cuadrado de 37 con una p This study had the purpose of evaluating the sensibility and specificity of the radiommunoguided-detection of perforations of the gastrointestinal tract utilizing Tenecium 99. The design was a prospective, experimental triple blinded study, with an estimation of the size of the sample considering a 95% sensitivity and specificity, an alpha error of 0.05, and a precision of 0.05. There was an initial evaluation in four New Zealand rabbits in order to determine: type of anesthesia and doses, capacity of the stomach (ml), average time interval of intestinal transit, abdominal cavity capacity (ml) and the distribution of the radio material (intestinal absorption, blood dissemination and distribution, and renal excretion). Forty New Zealand rabbits were utilized for analysis in three independent work stations, randomizing 20 rabbits to each study group (perforated and nonperforated). The radio material was colloidal sulphur labeled with Tecnecium 99, >100 nm, 2.5 mCi, a 140 Kev energy prepared in 0.9% saline solution, which provided a concentration of 0.0025 mCi per ml. Scan was done with gamma 10X probe. Statistical analysis was done with the Episet V:1 and the chi square test. All rabbits with disruption of the stomach exhibited positive radiaton activity in the peritoneal fluid, analyzing an average value of 467 and a rank of 37 to 1748. In the remaining rabbits with no perforation of the gastric wall the scan was negative. The sensitivity of this diagnostic method was 0.98 and the specificity 0.98, with a confidence interval of 0.92-1.0. Comparative gamma probe analysis of the peritoneal fluid in the two groups gave 37 chi square with a p

Introduction: Radiolabeled monoclonal antibodies (MAbs) have been a useful tool for diagnostic imaging and therapy in Oncology. The aim of this study was to carry out the indirect 99mTc radiolabeling of ior egf/r3, monoclonal antibody (MAb) specific for epidermal growth factor (EGF) receptor, and the comparison with a direct 99mTc radiolabeling approach., Material and Methods: Cyclic anhydride of the diethylenetriaminepentaacetic acid (ADTPA) was employed as bifunctional chelating agent in the indirect monoclonal antibody radiolabeling and it was coupled to MAb at molar ratios of 20:1, 50:1 and 200:1 (ADTPA:MAb). For the direct radiolabeling, the reduction of MAb was performed with 2-mercaptoethanol (2ME), based on Schwarz's method. Biological activity was measured by Flow Cytometry. Biodistribution studies were performed at 1, 3 and 24 h after injection of the radiolabeled antibody in Wistar rats., Results: After 30 min of 99mTc radiolabeling of the ior egf/r3 MAb, the radiochemical purity values were between 80.0 +/- 1.8 and 90.0 +/- 1.2 % for the indirect method using ADTPA, while it was 94.8 +/- 1.6 % for the direct approach using 2ME. Stability of the 99mTc-radiopharmaceuticals was similar for both methods. The biological activity was similar for both antibody formulations. There were no significant differences for the biodistribution to normal organs for both radiolabeled antibodies., Conclusions: Use of ADTPA was shown to be an efficient method for the 99mTc labeling of the monoclonal antibody ior egf/r3. Radiolabeling using 2ME showed higher radiochemical purity.

Objective: To assess the utility of nuclear imaging with labelled monoclonal antibody against CEA immu-4 Fab' (CEA-scan) and the computed tomography (CT) in the follow-up of colorectal cancer after therapy and his accuracy in the detection of recurrent disease., Materials and Methods: 48 studies underwent to 45 patients (25 men and 20 women) with an average age of 64, diagnosed and treated of colorectal cancer, 5 hours after the intravenous administration of 1.25 mg of arcitumomab (CEA-scan) labelled with 945 MBq of 99mTc. The reasons to request the CEA-scan were signs compatible with active disease in 15 cases, post-therapy control in asyntomatic patients in 17 and suspicious of recurrence in 16. Histological confirmation of the lesions was obtained in 12 patients and the rest was assessed by an average of evolution time of 26 months, CT and blood CEA levels., Results: The values of sensitivity, specificity, PPV and NPV obtained for the CEA- scan were of 91%, 76%, 77% y 90% respectively; 78%, 80%, 78% y 80% respectively for the CT and 65%, 42%, 88% y 74% respectively for the blood CEA levels. The CEA-scan and blood CEA levels combination showed the best results 100%, 95%, 93% y 100% respectively., Conclusion: We did not find any correlation between blood CEA levels and CEA-scan results. The CEA-scan showed the highest sensitivity an NPV. The combination of different techniques showed better results than an individual valoration.

Unlabelled: IOR C-5 is a G1 immunoglobulin type intact murine monoclonal antibody (MAb) that was developed in the Center of Molecular Immunology in Havana City, Cuba. In immunohistochemical studies, this demonstrated a significant affinity for the epithelial tissues so that it was used in a pilot clinical study to perform a radioimmunoscintigraphy of the colorectal primary tumors and their locoregional recurrences. It was labeled with 99mTc using the Schwarz method, with a > 95% performance. Planar images of the chest, abdomen and pelvis were performed at 10 minutes, 4-6 hours and 18-24 hours post-injection in the anterior and posterior projections and the SPECT was performed 4-6 hours and 18-24 hours post-injection of 1.85 GBq 99mTC. This study has aimed to verify in vivo the capacity of ior-C5 MAb to accumulate in the malignant colorectal lesions. ior-C5 accumulated in 5 out of the 7 patients who were studied and who were suffering from colorectal cancer or in whom there was suspicion of recurrence. There was a negative case of primary tumors, which was an adenocarcinoma in situ in a tubular-papillary adenoma. The second case with a negative radioimmunoscintigraphy was a true negative case., Conclusions: It can be concluded that even though the number of patients is quite low, ior-C5 fulfilled the expectations of recognizing the epitope expressed in colorectal tumors in an in vivo human environment.

Background: Cyclosporin A has an adequate immunosuppressive capacity and can be useful in the treatment of non infectious ocular inflammatory diseases., Aim: To describe the clinical effect of cyclosporin A treatment in low doses, along with corticosteroids, in the treatment of refractory ocular inflammatory diseases., Patients and Methods: Twenty patients (13 female), aged 17 to 74 years old with severe and refractory ocular inflammatory diseases were studied. All except one, received variable doses of prednisone (10 to 60 mg/kg/day) and all received cyclosporin in doses that started in 2.5 mg/day and were increased to 5 mg/kg/day, according to clinical response. Patients were followed from 8 to 24 months, with monthly assessments of ocular inflammation (using a four point score), visual acuity and adverse effects of treatment., Results: A two points or more reduction in the ocular inflammation score was observed in 52% of patients. Visual acuity improved in 10 subjects, stabilized in 8 and worsened in 2. Prednisone doses were reduced in most patients. Observed adverse effects were hypertension in 2 patients, creatinine elevation in 2, gastrointestinal disturbances in 3 and hypertrichosis in 12. A reduction of cyclosporin dose was required in these cases, but it was discontinued only in one patient with a vascular purpura., Conclusions: Low cyclosporin doses, associated to prednisone, are useful to reduce inflammation and improve visual acuity in patients with non infectious ocular inflammatory diseases, refractory to other treatment methods.

The anti-carcinoembryonic antigen (CEA) antibody, BW 431/26 (Scintimun CEA, Behringwerke, Marburg, Germany ) labeled with technetium pertechnectate (99mTc), is an intact immunoglobulin G1, monoclonal antibody that has been used to image colorectal cancer. Planar and SPECT images of chest, abdomen and pelvis were performed at 10 minutes, 4-6 and 18-24 hours after the intravenous antibody injection. 44 patients were studied and the pathological antibody concentration localization by radioimmunoimaging (RI) were correlated with surgical, clinical and other imaging modality findings to validate the RI. The RI was positive in 29 patients and negative in the other 15 patients. The CEA and CA 19.9 were elevated in the serum of some patients with primary tumors or recurrence. The HAMA were determined in all the patients before and after the RI.

A new Monoclonal Antibody (AcMo) ior-C5, highly specific for the most part of colorectal adenocarcinomas has been developed. The AcMo was labeled with 99mTc by the Schwarz's direct method using molar ratios MAb: reductant of 1:1,000 and 1:2,000. The first molar ratio was the most adequate for the preparation of the radiopharmaceutical. A labeling yield greater than 95% was obtained. Several <> assays were carried out in order to evaluate the stability of the preparation, whose results reflected the presence of the stable complex 99mTc-IgG. The biodistribution patterns for both preparations were similar. The excreting organs behaved like normal. Nevertheless, a greater renal excretion was observed for the preparation of the molar ratio of 1:2.000, which could be due to the presence of low affinity sites observed in this preparation. They are vulnerable to the trans-chelation of the 99mTc toward cysteine or glutathione present in plasma and tissues.

Background: The purpose of nuclear medicine in the evaluation of colorectal carcinoma is to complete the current diagnostic protocol, by means of monoclonal antibodies (MoAb) against tumoral antigens labelled with radioactive isotopes and performing an immunoscintigraphy., Patients and Methods: Immunoscintigraphies have been performed to 143 patients with colorectal carcinoma. Group I: antiCEA MoAb 99mTc-BW 431/26 (72 patients with 74 lesions, 48 primary tumors and 26 recurrences); group II: antiTAT-72 MoAb 111In-CYT-103 (71 patients with 75 lesions, 28 primary tumors and 47 recurrences). All positive images, not corresponding to physiological distribution of MoAb, have been considered as pathological., Results: The sensitivity in the diagnosis of primary tumors in group I was worse than in group II (54.2% vs 66.7%). If rectum tumors were excluded, the sensitivity increased to 80% and 85.7%, respectively. In the suspicion of recurrences, if only lesions confirmed at surgery were considered, the sensitivity was 75% in group I and 89.7% in group II. The immunoscintigraphy has been the only technique able to diagnose recurrences in 4/23 cases from group I and 14/32 from group II. In liver, considering as metastases only hot images, the sensitivity is very low in group I (44.4%) and null in group II. No relationship has been found between tumour markers levels and the immunoscintigraphic result., Conclusions: Immunoscintigraphy is useful in patients with colorectal carcinoma, especially in the case of recurrences and it is a complementary technique to other diagnostic procedures.

A 57 year old female had a tubular gastric adenocarcinoma confirmed by endoscopy and radiologic studies. Echotomography of the abdomen revealed multiple adenopathies. Immunoscintigraphy with 99mTc labeled anti-CEA BW 431/26 monoclonal antibody was performed. Images obtained at 6 and 24 h showed a significant uptake at the primary lesion and at periaortic adenopathies both in conventional gamma-camera and single emission photon tomography. This immuno-scintigraphic technique may be helpful in the management of patients with gastric cancer.