ABSTRACT Introduction: Prostate cancer (PC) is the second most commonly diagnosed cancer in males. 68Ga-PSMA PET/CT, a non-invasive diagnostic tool to evaluate PC with prostate-specific membrane antigen (PSMA) expression, has emerged as a more accurate alternative to assess disease staging. We aimed to identify predictors of positive 68Ga-PSMA PET and the accuracy of this technique. Materials and methods: Diagnostic accuracy cross-sectional study with prospective and retrospective approaches. We performed a comprehensive literature search on PubMed, Cochrane Library, and Embase database in search of studies including PC patients submitted to radical prostatectomy or radiotherapy with curative intent and presented biochemical recurrence following ASTRO 1996 criteria. A total of 35 studies involving 3910 patients submitted to 68-Ga-PSMA PET were included and independently assessed by two authors: 8 studies on diagnosis, four on staging, and 23 studies on restaging purposes. The significance level was α=0.05. Results: pooled sensitivity and specificity were 0.90 (0.86-0.93) and 0.90 (0.82-0.96), respectively, for diagnostic purposes; as for staging, pooled sensitivity and specificity were 0.93 (0.86-0.98) and 0.96 (0.92-0.99), respectively. In the restaging scenario, pooled sensitivity and specificity were 0.76 (0.74-0.78) and 0.45 (0.27-0.58), respectively, considering the identification of prostate cancer in each described situation. We also obtained specificity and sensitivity results for PSA subdivisions. Conclusion: 68Ga-PSMA PET provides higher sensitivity and specificity than traditional imaging for prostate cancer.

Resumo Objetivo: Determinar a frequência em que a PET/CT com FDG-18F muda a classificação de probabilidade de malignidade do nódulo pulmonar solitário. Materiais e Métodos: Foi realizada análise retrospectiva de todas as PET/CTs com FDG-18F realizadas entre maio/2016 e maio/2017 num serviço de medicina nuclear, cuja indicação era a avaliação de nódulo pulmonar solitário. Foram analisados os prontuários e os exames de PET/CT para coleta das informações necessárias para o cálculo da probabilidade pré-teste de malignidade pelo modelo de Swensen e pelo modelo de Herder. Probabilidade menor que 5% foi considerada como baixa, maior que 65% foi definida como alta, e os casos restantes, como intermediária. Os casos classificados como intermediários pelo modelo de Swensen foram reclassificados de acordo com o modelo de Herder. Resultados: Trinta e três pacientes foram incluídos neste estudo, 17 (51,5%) deles eram do gênero masculino, e a média de idade foi 68,63 anos (± 12,20 anos). Em relação à classificação da probabilidade de malignidade pelo modelo de Swensen, 23 (69,7%) apresentaram probabilidade intermediária de malignidade. Destes, o modelo de Herder classificou 6 casos (26,1%) como probabilidade baixa e 8 casos (34,8%) como probabilidade alta de malignidade. Conclusão: A PET/CT com FDG-18F foi capaz de modificar a classificação probabilística do nódulo pulmonar solitário em mais da metade dos casos.

Abstract Objective: To determine the frequency with which 18F-FDG-PET/CT findings change the probability of malignancy classification of solitary pulmonary nodules. Materials and Methods: This was a retrospective analysis of all 18F-FDG-PET/CT examinations performed for the investigation of a solitary pulmonary nodule between May 2016 and May 2017. We reviewed medical records and PET/CT images to collect the data necessary to calculate the pre-test probability of malignancy using the Swensen model and the Herder model. The probability of malignancy was classified as low if < 5%, intermediate if 5-65%, and high if > 65%. Cases classified as intermediate in the Swensen model were reclassified by the Herder model. Results: We reviewed the records for 33 patients, of whom 17 (51.5%) were male. The mean age was 68.63 ± 12.20 years. According to the Swensen model, the probability of malignancy was intermediate in 23 cases (69.7%). Among those, the application of the Herder model resulted in the probability of malignancy being reclassified as low in 6 (26.1%) and as high in 8 (34.8%). Conclusion: 18F-FDG-PET/CT was able to modify the probability of malignancy classification of a solitary pulmonary nodule in more than 50% of the cases evaluated.

The Guidelines Project, an initiative of the Brazilian Medical Association, aims to combine information from the medical field in order to standardize procedures to assist the reasoning and decision-making of doctors. The information provided through this project must be assessed and criticized by the physician responsible for the conduct that will be adopted, depending on the conditions and the clinical status of each patient.

The Guidelines Project, an initiative of the Brazilian Medical Association, aims to combine information from the medical field in order to standardize producers to assist the reasoning and decision-making of doctors. The information provided through this project must be assessed and criticized by the physician responsible for the conduct that will be adopted, depending on the conditions and the clinical status of each patient.

Resumo Objetivo: Avaliar se o PET/CT interim com fluoreto-18F após a terceira dose da terapia com dicloreto de rádio-223 (223Ra) é capaz de identificar pacientes que não responderão ao tratamento. Materiais e Métodos: Revisamos, retrospectivamente, 34 pacientes com diagnóstico histológico de câncer de próstata refratários a hormonioterapia e com metástases ósseas que foram submetidos a 223Ra. Todos os pacientes foram submetidos a PET/CT com fluoreto-18F antes de iniciar o tratamento (basal) e imediatamente antes da quarta dose de 223Ra (interim). A carga tumoral esquelética (TLF10) foi calculada em ambos os exames da PET/CT com fluoreto-18F de cada paciente e foi determinada a alteração percentual na TLF10 entre eles (%TFL10 = TLF10 interim - TLF10 basal / TLF10 basal). Foram avaliados a sobrevida global, a sobrevida livre de progressão e o tempo para um evento ósseo. Resultados: A idade média dos pacientes foi 72,4 ± 10,2 anos (variação: 43,3-88,8 anos). A %TLF10 não foi capaz de predizer a sobrevida global (p = 0,6320; HR = 0,753; intervalo de confiança [IC] 95%: 0,236-2,101), a sobrevida livre de progressão (p = 0,5908; HR = 1,248; IC 95%: 0,557-2,797) nem o tempo para um evento ósseo (p = 0,5114; HR = 1,588; IC 95%: 0,399-6,312). Conclusão: A carga tumoral esquelética da PET/CT com fluoreto-18F realizada após três doses de 223Ra não é capaz de predizer sobrevida global, sobrevida livre de progressão ou tempo até um evento ósseo, e não deve ser realizada para monitorar a resposta ao tratamento desses pacientes, nesse momento.

Abstract Objective: To determine whether an interim 18F-fluoride positron-emission tomography/computed tomography (PET/CT) study performed after the third cycle of radium-223 dichloride (223RaCl2) therapy is able to identify patients that will not respond to treatment. Materials and Methods: We retrospectively reviewed 34 histologically confirmed cases of hormone-refractory prostate cancer with bone metastasis in patients submitted to 223RaCl2 therapy. All of the patients underwent baseline and interim 18F-fluoride PET/CT studies. The interim study was performed immediately prior to the fourth cycle of 223RaCl2. The skeletal tumor burden-expressed as the total lesion fluoride uptake above a maximum standardized uptake value of 10 (TLF10)-was calculated for the baseline and the interim studies. The percent change in TLF10 between the baseline and interim studies (%TFL10) was calculated as follows: %TFL10 = interim TLF10 - baseline TLF10 / baseline TLF10. End points were overall survival, progression-free survival, and skeletal-related events. Results: The mean age of the patients was 72.4 ± 10.2 years (range, 43.3-88.8 years). The %TLF10 was not able to predict overall survival (p = 0.6320; hazard ratio [HR] = 0.753; 95% confidence interval [CI]: 0.236-2.401), progression-free survival (p = 0.5908; HR = 1.248; 95% CI: 0.557-2.797) nor time to a bone event (p = 0.5114; HR = 1.588; 95% CI: 0.399-6.312). Conclusion: The skeletal tumor burden on an interim 18F-fluoride PET/CT, performed after three cycles of 223RaCl2, is not able to predict overall survival, progression-free survival, or time to bone event, and should not be performed to monitor response at this time.