INTRODUCTION: Renal artery stenosis can lead to renovascular hypertension; however, the detection of stenosis alone does not guarantee the presence of renovascular hypertension. Renovascular hypertension depends on activation of the renin-angiotensin system, which can be detected by functional tests such as captopril renal scintigraphy. A method that allows direct measurement of the baseline and post-captopril glomerular filtration rate using chromium-51 labeled ethylenediamine tetraacetic acid (51Cr-EDTA) could add valuable information to the investigation of hypertensive patients with renal artery stenosis. The purposes of this study were to create a protocol to measure the baseline and post-captopril glomerular filtration rate using 51Cr-EDTA, and to verify whether changes in the glomerular filtration rate permit differentiation between hypertensive patients with and without renal artery stenosis. METHODS: This prospective study included 41 consecutive patients with poorly controlled severe hypertension. All patients had undergone a radiological investigation of renal artery stenosis within the month prior to their inclusion. The patients were divided into two groups: patients with (n=21) and without renal artery stenosis, (n=20). In vitro glomerular filtration rate analysis (51Cr-EDTA) and 99mTc-DMSA scintigraphy were performed before and after captopril administration in all patients. RESULTS: The mean baseline glomerular filtration rate was 48.6±21.8 ml/kg/1.73 m² in the group wuth renal artery stenosis, which was significantly lower than the GFR of 65.1±28.7 ml/kg/1.73m² in the group without renal artery stenosis (p=0.04). Captopril induced a significant reduction of the glomerular filtration rate in the group with renal artery stenosis (to 32.6±14.8 ml/kg/1.73m², p=0.001) and an insignificant change in the group without RAS (to 62.2±23.6 ml/kg/1.73m², p=0.68). Scintigraphy with technetium-99m dimercapto-succinic acid (DMSA) did not show significant differences in differential renal function from baseline to post-captopril images in either group. CONCLUSIONS: Captopril induced a decrease in the GFR that could be quantitatively measured with 51Cr-EDTA. The reduction is more pronounced in hypertensive patients with RAS.

OBJETIVO: O estudo metabólico com 18F-fluorodeoxiglicose é uma ferramenta útil para o manejo de portadores de linfoma de Hodgkin, tanto como método auxiliar no estadiamento da doença, quanto na avaliação de massas suspeitas encontradas após tratamento. O objetivo deste estudo foi investigar o valor do estudo com 18F-fluorodeoxiglicose em gama câmara híbrida no estadiamento e na detecção de tumor residual em pacientes com linfoma de Hodgkin. MÉTODOS: Trinta e oito pacientes foram incluídos neste estudo retrospectivo, 18 foram avaliados com o estudo metabólico durante o estadiamento (Grupo 1), sendo os resultados do estudo comparados com os obtidos com o estadiamento convencional, que incluiu tomografia e biópsia de medula óssea. Os 20 pacientes restantes realizaram o estudo metabólico devido à presença de massa residual ou de nova lesão suspeita (Grupo 2). RESULTADOS: O estudo metabólico aumentou o estádio de cinco (27%) dos pacientes do Grupo 1 e pôde detectar mais lesões que os métodos convencionais de estadiamento (45 lesões detectadas com 18F-fluorodeoxiglicose versus 33 lesões métodos convencionais). Nos 20 pacientes do Grupo 2, 11 foram 18F-fluorodeoxiglicose positivos e tumor viável foi confirmado em 9 pacientes. Nos 9 pacientes com estudo metabólico negativo, a probabilidade de recidiva em um ano foi de 11.8%. A sensibilidade, especificidade, valor preditivo positivo, valor preditivo negativo e a acurácia do estudo metabólico foram de 90%, 80%, 82%, 89% e 85% respectivamente. CONCLUSÕES: O estudo com 18F-fluorodeoxiglicose apresentou melhor acurácia que os métodos convencionais de estadiamento do Linfoma de Hodgkin e foi útil para o diagnóstico não-invasivo de lesões suspeitas.

OBJECTIVE: The metabolic test using 18F-fluorodeoxyglucose is a useful tool for the management of patients with Hodgkin lymphoma, either for staging purposes or for the evaluation of suspicious masses that can frequently occur after treatment. The aim of the present study was to investigate the value of the 18F-fluorodeoxyglucose test performed with a dual-head coincident gamma camera (CGC-PET with fluorodeoxyglucose) for the staging and the detection of residual tumor of patients with Hodgkin lymphoma. METHODS: Thirty-eight consecutive patients were included in this retrospective study; the metabolic test comprising CGC-PET with FDG was done in 18 patients for staging work-up (Group 1), and the results were compared to conventional clinical staging procedures that included computed tomography scans and bone marrow biopsy. The remaining 20 patients were evaluated with CGC-PET with fluorodeoxyglucose due to the presence of residual masses or a new lesion (Group 2). RESULTS: The 18F-Fluorodeoxyglucose metabolic test, CGC-PET with fluorodeoxyglucose, upstaged 5 (27%) of the Group 1 patients and detected more lesions (45) than conventional methods of staging (33). Of the 20 patients in Group 2, 11 had positive18F-fluorodeoxyglucosetests, and a viable tumor was confirmed in 9 patients. Regarding the 9 patients with negative fluorodeoxyglucose metabolic tests, the 1-year probability of recurrence was 11.8%. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the CGC-PET with fluorodeoxyglucose test were 90%, 80%, 82%, 89%, and 85% respectively. CONCLUSIONS: The metabolic test comprising CGC-PET with fluorodeoxyglucose had a higher diagnostic accuracy than conventional methods in the staging of Hodgkin lymphoma and thus is a valuable noninvasive tool for the diagnosis of suspicious lesions.