First-pass scintigraphy with (99m)Tc macroaggregated albumin: a method for evaluating pulmonary arterial flow pulsatility.

OBJECTIVES: The aim of this work was to develop and describe a non-invasive scintigraphic technique to detect flow pulsatility in peripheral pulmonary arteries. METHODS: Ten normal volunteers were submitted to a first-pass scintigraphy using Tc macroaggregated albumin (Tc-MAA). A time-activity curve was generated for the right lung lateral third. Activity was shown to be restricted to the arterial compartment of the lungs, since there was no detectable progression of the radiopharmaceutical to the systemic circulation. Consequently, the rise in lung activity was attributed to the arterial inflow and the first derivative of the time-activity curve was assumed to represent pulmonary arterial flow. RESULTS: Pulmonary flow curves showed two main positive peaks in six volunteers, followed by a third small peak in three others. Flow was predominant during systole, with an important reduction in magnitude before the diastolic peak, leading to a negative count variation in eight subjects. This pattern is comparable to that described in central pulmonary vessels by different methods. CONCLUSIONS: First-pass scintigraphy with Tc-MAA was able to detect flow pulsatility in pulmonary arteries. These results need to be confirmed in a larger number of individuals, and, if shown to be reproducible, may increase our understanding of lung flow physiology, and of its modifications in the presence of cardiopulmonary diseases.

Brain spect in dementia: a clinical-scintigraphic correlation

The aim of this study was to compare the accuracy of computed tomography (CT) and single photon emission computerized tomography (SPECT) in the diagnosis of dementia. Fifty-two patients with clinical diagnosis of dementia and 11 controls were studied. The scans were interpreted by one experienced neuroradiologist and one nuclear radiologist, both blinded to the clinical data. In the diagnosis of dementia, CT and SPECT showed equal sensitivity (82.7 per cent) and statistically similar specificity (63.8 and 81.8 per cent, respectively). The specificity of SPECT in diagnosing Alzheimer's disease (100 per cent) was statistically superior to CT (69 per cent). However, both methods showed similar sensitivity in detecting Alzheimer's disease. In conclusion, SPECT and CT showed similar accuracy in the diagnosis of dementia. The quite high specificity of SPECT in Alzheimer's disease may be useful for confirming that diagnosis, particularly for patients with presenile onset of the disease.

Brain spect in the pre-surgical evaluation of epileptic patients: preliminary results

A avaliaçäo pré-operatória de pacientes epilépticos consiste basicamente de exame neurológico, monitorizaçäo intensiva de EEG e estudos anatômicos (CT e RMN). Métodos funcionais como PET e SPECT têm sido utilizados mais frequentemente nos últimos anos. Foi realizada a investigaçäo pré-operatória em 15 pacientes epilépticos adultos (8 mulheres, 7 homens) utilizando câmara de cintilaçäo rotacional acoplada a computador. As imagens tomográficas foram obtidas 15 minutos após a injeçäo de 99mTC HMPAO. Todos os pacientes foram submetidos a RMN e monitorizaçäo intensiva de EEG, que geralmente inclui registros ictais. cinco pacientes possuiam lesöes expansivas (3 meningiomas e 2 astrocitomas). Em 10 pacientes, os estudos neurorradiológicos näo mostraram presença de lesöes expansivas (2 normais e 8 com lesöes inativas). O estudo de 2 pacientes com meningeomas mostrou presença de hipoperfusäo ao nível da lesäo, enquanto em um terceiro caso marcada hiperperfusäo foi detectada e, neste paciente, provavelmente correlacionava-se quadro de epilepsia partialis continua. Nos pacientes com astrocitomas, os exames de SPECT mostraram hipoperfusäo no local da lesäo. Os dados obtidos em pacientes näo portadores de lesöes expansivas do sistema nervoso mostraram: (a) em 4 casos os achados de SPECT, correlacionaram-se bem aos achados anatômicos; (b) em 5 casos, os achados de SPECT mostraram déficits de fluxo adicionais a lesäo anatomica; (c) em um caso, näo houve correlaçäo entre os achados de SPECT e uma pequena lesäo anatômica. Em 5 casos com lesöes näo progressivas (n = 10) os achados de SPECT foram úteis na determinaçäo da conduta cirúrgica. Apesar do pequeno número e da heterogeneidade da presente amostra, o SEPECT parece ser importante método complementar no arsenal clínico-propedêutico de pacientes epilépticos candidatos a cirurgia