The combination of positron emission tomography (PET) with magnetic resonance imaging (MRI) has been the subject of several studies in recent years. Positron emission tomography is the most sensitive and specific imaging modality in the detection of metabolic changes, but presents limited spatial resolution. On the other hand, MRI presents a significant spatial resolution, besides evaluating soft tissues signal intensity with excellent contrast resolution. The present iconographic essay is aimed at demonstrating the potential clinical application of PET/MRI coregistration. The studies were performed in a dedicated PET unit with 18F-fluorodeoxyglucose (FDG) as radiopharmaceutical and coregistered with 1.5 T or 3 T brain MRI. The brain images fusion software presents an already well-established accuracy, so a significant synergy between a functional PET study and an excellent MRI anatomical detail is achieved. The most attractive clinical applications of this approach are the following: epileptogenic zone assessment in patients refractory to drug therapy, identification of patients with cognitive impairment at higher risk for progression to dementia and differentiation of dementias and Parkinsonian syndromes.

Keywords: Fluorodeoxyglucose, FDG, Positron emission tomography, PET, Magnetic resonance imaging, Fusion, Clinical neurology

Malignant melanoma is a common and aggressive disease that frequently causes metastases to the small bowel. This study illustrates a case of small bowel intussusception secondary to metastatic melanoma visualized at 18F-FDG PET/CT in a 48-year-old woman who had this examination for restaging purposes.

Keywords: PET/CT, Melanoma, Intussusception

We describe imaging findings of a oesophageal liposarcoma in a 66 year old man. The computed tomography scan was performed after a chest radiograph showed a large posterior mediastinal mass. Oesophageal liposarcomas are rare tumours. They can achieve large size before they become symptomatic. Our patient was successfully managed with complete surgical removal.

Keywords: Liposarcoma, Oesophagus, Computed tomography scan

Radiation therapy represents an important alternative for curative treatment of patients with nonsmall cell lung cancer. However, an accurate definition of the volume to be irradiated becomes even more important, considering that lungs are highly sensitive to radiation. Most recently, combined FDG-PET/CT scan has been utilized, and the literature reports its significant role in the planning of radiation therapy, since it seems to influence the target-volume delineation in cases of lung cancer. Differences between diagnostic and treatment equipments must be taken into consideration when FDG-PET/CT scan is utilized in the planning of radiation therapy. The present study discusses some of the many technical problems that must be solved when PET is incorporated into the planning of radiation therapy for non-small cell lung cancer.

Keywords: Radiotherapy, PET scan, Planning, Lung cancer

OBJECTIVE: To identify the most frequent aspects of spontaneous cerebral intraparenchymatous hematoma found at computed tomography examinations. MATERIALS AND METHODS: We reviewed, retrospectively, the computed tomography studies of 250 patients with spontaneous intracerebral hemorrhage carried out in three hospitals in Rio de Janeiro, Brazil. RESULTS: Deep intracerebral hematomas showed the highest incidence and were observed in 54.4% of the cases (136 patients) followed by lobar hemorrhage in 34.8% of the cases (87 patients). Cerebelar hemorrhage and brainstem bleeding were more rarely observed, occurring in 8.4% (21 patients) and 2.4% (six patients) of the cases, respectively. CONCLUSION: Chronic headache was the most frequent symptom whereas hypertension was observed in the majority of the cases. Blood draining into the ventricular system occurred more frequently in patients with deep hematomas.

Keywords: Intracerebral hemorrhage, Computed tomography scan, Hypertension, Headache

Mediastinal neoplasms of mesenchymal origin are rare, accounting for less than 6% of these tumors. Most of these tumors are liposarcomas, although cystic lesions are uncommon. The authors present a case of a 58-year-old woman with progressively worsening dyspnea since she was 52-years-old. Laryngeal stridor was auscultable and a chest CT scan showed a cystic lesion in the posterior mediastinum. The tumor was resected and the histological examination revealed myxoid liposarcoma.

Keywords: Computed tomography scan imaging, Medistinal tumors, Myxoid liposarcoma

Objetivo: A principal utilidade da tomografia por emissão de pósitrons com 18-fluordeoxiglicose (FDG-PET) está no estadiamento do câncer de pulmão. Porém, ela também pode ser utilizada para diferenciar lesões pulmonares indeterminadas, mas seu impacto na ressecção cirúrgica de lesões benignas é desconhecido. O objetivo deste estudo foi comparar a prevalência de lesões benignas em toracotomias feitas por suspeição de câncer de pulmão, antes e após a introdução do FDG-PET, em um centro de referência de cirurgia torácica. Materiais e Métodos: Os autores analisaram, prospectivamente, uma base de dados cirúrgicos de todos os pacientes consecutivos submetidos a toracotomia por câncer de pulmão suspeito ou comprovado e compararam a prevalência de lesões benignas em dois grupos ao longo de dois anos consecutivos, respectivamente antes (grupo I) e depois (grupo II) da introdução da FDG-PET. Resultados: Ressecção cirúrgica foi feita em 1.233 pacientes durante o período do estudo. A prevalência de lesões benignas na cirurgia nos grupos I e II foi similar (44/626 e 41/607, ambas correspondendo a 7%), e também no grupo II, entre aqueles submetidos a FDG-PET e os restantes (21/301 e 20/306 respectivamente, ambos correspondendo a 7%). No grupo II, dos 21 pacientes com lesões benignas submetidos a FDG-PET, 19 tiveram um estudo falso-positivo (valor médio padrão de captação 5.3 [faixa 2.6–12.7]). Desses, respectivamente 13 e 4 pacientes tiveram broncoscopia não diagnóstica e biópsia transtorácica percutânea de pulmão antes da toracotomia. Não houve diferença na proporção de lesões benignas diferentes ressecadas entre o grupo I e aqueles submetidos a FDG-PET no grupo II. Conclusão: A introdução da FDG-PET não alterou a proporção de pacientes submetidos a toracotomia por lesões benignas, principalmente devido à avidez pelo isótopo de algumas lesões não malignas. Tais resultados falsos-positivos devem ser considerados nos casos em que se contempla a possibilidade de ressecção cirúrgica em pacientes com câncer de pulmão não confirmado.

Keywords: Tomografia por emissão de pósitrons; Tomografia computadorizada; Pulmão – lesões benignas ou congênitas; Câncer de pulmão – diagnóstico e estadiamento; Câncer de pulmão – cirurgia.

Objetivo: Avaliar a percepção de médicos residentes em radiologia de 4º ano sobre as melhores modalidades de imagem na investigação de neoplasias e trauma. Materiais e Métodos: Vinte e sete médicos residentes de 4º ano de quatro programas de residência em radiologia americanos participaram do estudo. Aos participantes foi perguntado sobre a melhor modalidade de imagem para se avaliar o cérebro e a coluna vertebral, pulmões, abdome e o sistema musculoesquelético. As modalidades de imagem disponíveis foram: RM, TC, ultrassonografia, PET e radiografia simples. Todos os achados foram comparados com os Critérios de Adequação de Exames de Imagem e Radioterapia do ACR. Resultados: A RM foi escolhida como melhor modalidade de imagem para se avaliar neoplasias encefálicas, espinhais, abdominais e musculoesqueléticas por 96,3%, 100%, 70,4% e 63% dos residentes, respectivamente. A TC foi escolhida por 88,9% dos residentes para avaliar neoplasias pulmonares. A modalidade de imagem ótima para se avaliar trauma foi a TC para lesões encefálicas (100%), espinhais (92,6%), pulmonares (96,3%), abdominais (92,6%) e grandes lesões traumáticas musculoesqueléticas (74,1%); a RM foi escolhida para lesões esportivas (96,3%). Observou-se concordância com os critérios de adequação do ACR. Conclusão: Houve concordância entre a percepção dos residentes sobre as melhores modalidades de imagem para avaliação de neoplasias e trauma e os critérios de adequação do ACR.

Keywords: Formação de residentes; Educação médica; Modalidades de imagem.

Breast hemangioma is a rare benign tumor that presents either absent or low 18F-fluoro-2-deoxy-D-glucose (FDG) uptake at positron emission tomography (PET). The authors report the case of a breast nodule pathologically compatible with hemangioma in a woman whose PET-scan has demonstrated increased FDG uptake (simulating a malignant tumor). A brief review of factors leading to false positive and false negative PET results is also undertaken.

Keywords: PET/CT; FDG-18F; Hemangioma; Breast.

OBJECTIVE: To evaluate the accuracy and cost-effectiveness of metabolic staging (MS) with FDG-PET as compared with the conventional staging (CS) strategy in the preoperative staging of non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: A total of 95 patients with initial diagnosis of NSCLC were staged before undergoing treatment. The MS and CS results were compared with regard to treatment definition and incidence of futile thoracotomies with both strategies. RESULTS: Metabolic staging with FDG-PET upstaged 48.4% and downstaged 5.3% of the patients, and would lead to change in the treatment of 41% of cases. Thoracotomy was considered as futile in 47% of the patients with CS, and in 19% of the patients with MS. The cost of futile thoracotomies in eight patients with MS was R$ 79,720, while in 31 patients with CS it would be R$ 308,915. Just such saving in costs would be more than enough to cover the costs of all FDG-PETs (R$ 126,350) or FDG-PET/CTs (R$ 193,515) for the 95 patients. CONCLUSION: The metabolic staging with FDG-PET is more accurate than CS in patients with NSCLC. Both FDG-PET and FDG-PET/CT are cost-effective methods and their utilization is economically justifiable in the Brazilian public health system.

Keywords: Non-small cell lung cancer; FDG-PET; Staging; Cost-effectiveness.

OBJETIVO: Avaliar a completude das fissuras, resposta radiológica ao tratamento e análise quantitativa por TC (AQTC) em população de pacientes com enfisema grave submetidos ao implante de valvas endobrônquicas (VEB). MATERIAIS E MÉTODOS: Foram estudados exames de TC multidetectores de 29 pacientes, realizados com protocolo de baixo dose, cortes finos, sem contraste. Dois radiologistas revisaram, retrospectivamente, os exames em consenso. A completude das fissuras foi estimada em escala de 5% e a resposta radiológica (atelectasia/perda volumétrica do lobo alvo) foi avaliada. AQTC foi realizada nos exames pré e pós-tratamento utilizando programa completamente automático. RESULTADOS: Resposta radiológica positiva foi vista em 16/29 pacientes. Os 13 pacientes sem resposta à TC apresentavam fissuras incompletas e completude média das fissuras obliquas de 72,8%, contra 88,3% no outro grupo. Os resultados mais significativos da AQTC mostraram redução do volume pulmonar (VP) total (média de 542 ml), VP tratado (700 ml) e volume de enfisema (331,4 ml) no grupo com resposta positiva, que também apresentou melhora nos testes funcionais. CONCLUSÃO: O benefício das VEB é maior em pacientes com fissuras completas e que desenvolvem atelectasia lobar. Nos pacientes sem resposta radiológica encontramos maior prevalência de fissuras incompletas e grau de incompletude das fissuras. Nossa AQTC automática detectou as alterações pós-tratamento, principalmente considerado a análise do pulmão tratado.

Keywords: Enfisema; Terapia de colapso pulmonar; Tomografia computadorizada.

OBJECTIVE: To correlate the results of ¹⁸F-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) performed with a specific protocol for assessment of breasts with histological/immunohistochemical findings in breast carcinoma patients. MATERIALS AND METHODS: Cross-sectional study with prospective data collection, where patients with biopsy-confirmed breast carcinomas were studied. The patients underwent PET/CT examination in prone position, with a specific protocol for assessment of breasts. PET/CT findings were compared with histological and immunohistochemical data. RESULTS: The authors identified 59 malignant breast lesions in 50 patients. The maximum diameter of the lesions ranged from 6 to 80 mm (mean: 32.2 mm). Invasive ductal carcinoma was the most common histological type (n = 47; 79.7%). At PET/CT, 53 (89.8%) of the lesions demonstrated anomalous concentrations of ¹⁸F-FDG, with maximum SUV ranging from 0.8 to 23.1 (mean: 5.5). A statistically significant association was observed between higher values of maximum SUV and histological type, histological grade, molecular subtype, tumor diameter, mitotic index and Ki-67 expression. CONCLUSION: PET/CT performed with specific protocol for assessment of breasts has demonstrated good sensitivity and was associated with relevant histological/immunohistochemical factors related to aggressiveness and prognosis of breast carcinomas.

Keywords: Breast cancer; PET/CT; Histology.

OBJECTIVE: To evaluate the level of ambient radiation in a PET/CT center. MATERIALS AND METHODS: Previously selected and calibrated TLD-100H thermoluminescent dosimeters were utilized to measure room radiation levels. During 32 days, the detectors were placed in several strategically selected points inside the PET/CT center and in adjacent buildings. After the exposure period the dosimeters were collected and processed to determine the radiation level. RESULTS: In none of the points selected for measurements the values exceeded the radiation dose threshold for controlled area (5 mSv/year) or free area (0.5 mSv/year) as recommended by the Brazilian regulations. CONCLUSION: In the present study the authors demonstrated that the whole shielding system is appropriate and, consequently, the workers are exposed to doses below the threshold established by Brazilian standards, provided the radiation protection standards are followed.

Keywords: Dosimetry; Thermoluminescence dosimetry; PET/CT.

PET/CT is widely used for the evaluation of patients with thoracic malignancies. Although the levels of ¹⁸F-fluorodeoxyglucose (FDG) uptake are usually high in neoplastic diseases, they can also be physiological, due to artifacts. In addition, FDG uptake can occur in benign conditions such as infectious, inflammatory, and iatrogenic lesions. Furthermore, some malignant tumors, such as adenocarcinoma in situ (formerly known as bronchoalveolar carcinoma) and carcinoid tumors, may not show FDG uptake. Here, we illustrate the main pitfalls and artifacts in the interpretation of the results of oncologic PET/CT of the chest, outlining strategies for avoiding misinterpretation.

Keywords: Pitfalls; Chest; PET/CT; Oncology.

OBJETIVO: Avaliar os padrões tomográficos relacionados aos agentes etiológicos da pneumonia em pacientes durante o primeiro ano após transplante renal. MATERIAIS E MÉTODOS: Foram analisados dados de prontuários de 956 pacientes submetidos a transplante renal, no período de 2013 a 2018, em um centro transplantador renal do nordeste do Brasil. Nos pacientes que desenvolveram pneumonia, os agentes etiológicos foram classificados em bactérias piogênicas, micobactérias, fungos, vírus e pneumonia polimicrobiana, enquanto os padrões tomográficos foram classificados em consolidação, broncopneumonia, pneumonia intersticial e nódulos e massas. Para verificar associação estatística entre micro-organismos e padrões tomográficos, foi utilizado o teste exato de Fisher, com p < 0,001. RESULTADOS: Foram encontrados 101 casos de pneumonia, dos quais 60 (59,4%) tiveram agente etiológico identificado, sendo as bactérias piogênicas as mais frequentes, detectadas em 22 (36,7%) dos casos. Entre os pacientes com agente causal identificado, o padrão tomográfico predominante foi o de nódulos e massas, identificado em 25 (41,7%) casos. Foi observada associação entre bactérias piogênicas e o padrão de consolidação, fungos com nódulos e massas, bem como entre agentes virais e padrão intersticial. CONCLUSÃO: Foi demonstrada associação estatística entre micro-organismos causadores de pneumonia e padrões tomográficos, informação que pode contribuir para o planejamento da terapia de pacientes transplantados renais.

Keywords: Pneumonia; Transplante de rim; Tomografia computadorizada.