Sentinel node mapping reduces surgical morbidity and allows the use of more accurate tumour staging techniques. Radionuclide studies are preferentially performed using small colloids, which have limited availability in our country. The possibility of using phytate for sentinel node mapping was raised because of the similarity between its biodistribution and that of nanocolloids in the reticulo-endothelial system. In this paper we evaluated the use of 99mTc-phytate for sentinel node mapping, correlating the histopathological results with the status of the rest of the lymph node chain in different malignant tumours. A total of 100 patients were studied. group 1 consisted of 62 patients with breast cancer, group 2 of 20 patients with melanoma and group 3 of 18 patients with vulvar carcinoma. Lymph node scintigraphy was carried out after injecting 99mTc-phytate subdermally, and the sentinel node projection was marked on the skin. After 18-24 h, intraoperative sentinel node localisation was performed using a gamma probe (combined with visual localisation using patent blue dye) in 75 patients, and lymph node dissection was then carried out. Radionuclide scintigraphy identified the sentinel node in 98% of all studies. Intraoperative detection using the gamma probe was equally efficient: group 1=93% (38/41), group 2=95% (18/19) and group 3=100% (15/15). The sentinel node was involved in 41%, 31% and 20% of cases in groups 1, 2 and 3, respectively. Among the patients with positive nodes, the sentinel node was the only one affected in 53% of group 1, 50% of group 2 and 67% of group 3 cases. The method's negative predictive value was 91% in group 1 and 100% in the other groups. One false-negative study occurred in a patient who had a multifocal tumour and an intraparenchymatous lymph node; another occurred in a patient with a macroscopically affected node found during surgery. There were no side-effects related to the 99mTc-phytate. It is concluded that scintigraphic and intraoperative sentinel node identification was satisfactorily performed using 99mTc-phytate. The results were comparable to those previously described in the literature using other radiopharmaceuticals. Easy availability and low cost justify the use of phytate in our practice.

RESUMOObjetivo: Analisar medidas tomadas para aumentar a dose de radiação absorvida (DOSE) durante o tratamento do carcinoma diferenciado da tireóide (CDT) com iodo-131. Métodos: As abordagens para aumentar a DOSE na radioiodoterapia são: redução da competição com iodo não-radioativo, estímulo da captação/retenção celular e aumento da atividade administrada. Revisaram-se os fundamentos e resultados de cada um destes métodos. Resultados: Apesar de ser difícil confirmar aumento de sobrevida, existe relação direta entre a DOSE e a resposta no CDT. Diferentes abordagens permitem o aumento da DOSE nos tecidos, inferindo-se uma possível melhora na resposta dos tumores ao tratamento com iodo-131. Apesar do prognóstico relativamente benigno da doença, a melhoria da resposta é importante nos casos de alto risco, em que as alternativas de tratamento são limitadas. Conclusões: As intervenções descritas permitem aumentar a DOSE durante o tratamento do CDT, podendo ser empregadas para casos de alto risco. Our aim was to analyze measures taken to increase the radiation absorbed dose (DOSE) during treatment of well-differentiated thyroid cancer (DTC) with iodine-131. Methods: An increase in DOSE is achieved by: avoiding competition with non-radioactive iodine, stimulating cellular uptake/retention, increasing the administered activity. Basis and results of each one of these methods were reviewed. Results: Although it is difficult to demonstrate an increase in survival, there is a direct relation between DOSE and tumoral response in DTC. Different approaches can be used aiming an increase in DOSE, with a possible improvement in tumoral response for treatment with iodine-131. Although DTC is a relatively benign disease, a better response to treatment is highly desirable in high-risk patients, who have few other options of therapy. Conclusions: An increase in DOSE during treatment of DTC can be achieved using the described interventions, which should be used in high-risk cases of DTC.

Nuclear medicine procedures that use I activity represent significant sources of potential absorbed dose to medical staff, volunteers, and the general public. The potential exposures are due principally from exposures to excreted and retained activities in the patients' bodies. In general, exposure rate decreases in a simple exponential manner. The average effective half-life found for all patients in the study reported here is 11.41 +/- 0.02 h; this information may be used in guidelines on the management of patients in thyroid cancer therapy and for general radioprotection practice.

Resumo: FUNDAMENTOS -A progressão linfática do melanoma maligno habitualmente se inicia pelo linfonodo sentinela (LNS), cuja análise histopatológica permite predizer o acometimento de toda a cadeia. OBJETIVO Tc-Fitato, que apresenta vantagens de custo e disponibilidade no Brasil. A pesquisa de LNS resulta em maior acurácia e menor morbidade no estadiamento de pacientes com melanoma maligno Palavras-chave: biópsia de linfonodo sentinela; cintilografia; melanoma. Summary: BACKGROUND -Sentinel lymph node (SLN), corresponding to the first lymph node draining the tumor, is usually the first one to receive its metastasis, and its biopsy is used to define the status of the whole lymphatic basin. OBJECTIVE -The aim of this paper is to describe the use 99mTc-Fitato in SLN

288 ResumoObjetivo: Avaliar se diferentes parâmetros de análise da linfocintilografia permitem a distinção entre membros com e sem linfedema em pacientes com quadro clínico de edema unilateral.Métodos: Levantamento retrospectivo dos exames de 20 pacientes submetidos a linfocintilografia para investigação de edema unilateral de membros inferiores, divididos em pacientes com linfedema primário (grupo 1, n = 7) ou secundário pós-traumático (grupo 2, n = 13). Foi realizada linfocintilografia após injeção subdérmica de soroalbumina humana marcada com tecnécio-99m nos pés, com imagens da região inguinal durante 15 min e imagens dos membros inferiores após 15 min e 1 h. Os parâmetros analisados foram: tempo de aparecimento da cadeia inguinal, índice semiquantitativo (fluxo linfático, difusão intersticial, aspecto dos vasos, tempo de aparecimento e aspecto dos linfonodos inguinais) e inclinação da curva de atividade em função do tempo da região inguinal. As medidas nos membros clinicamente acometidos foram comparadas aos membros sem linfedema em ambos os grupos.Resultado: O tempo médio de aparecimento da cadeia inguinal e o índice semiquantitativo foram significativamente maiores nos membros com linfedema que nos membros sem linfedema quando considerados todos os pacientes, com maior retardo e índice semiquantitativo nos membros com linfedema do grupo 1 em relação aos do grupo 2.Conclusão: A análise do tempo de aparecimento da cadeia inguinal e o índice semiquantitativo fornecem parâmetros objetivos de avaliação do linfedema que podem auxiliar na detecção e seguimento dos pacientes com linfedema.Palavras-chave: Cintilografia, linfedema. AbstractObjective: To evaluate whether different parameters could be used in the analysis of lymphoscintigraphy to distinguish affected from unaffected limbs in patients with unilateral edema.Methods: Twenty patients who underwent lymphoscintigraphy for screening of unilateral lower limb edema were retrospectively assessed and divided into patients with primary lymphedema (group 1, n = 7) or secondary post-traumatic edema (group 2, n = 13). Technetium 99m-labeled human serum albumin was subdermally administered in the feet, followed by a dynamic lymphoscintigraphy of the pelvis during 15 min and static images of the lower limbs after 15 min and 1 h. Analyzed parameters were detection time of groin activity, semi-quantitative index (lymph flow, interstitial diffusion, aspect of vessels, detection time and aspect of inguinal lymph nodes) and slope of groin time-activity curve. The parameters of clinically affected limbs were compared to those of the contralateral limbs in both groups.Results: Detection time of groin activity and semi-quantitative index were significantly higher in affected limbs considering all patients, with a more severe delay and a higher semi-quantitative index in group 1 compared to group 2.Conclusion: Analysis of detection time of groin activity and semiquantitative index can add objective parameters that can be used in the diagnosis and follow-up of patients with ly...