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Molecular imaging markers can be used to differentiate between infection and aseptic inflammation, determine the severity of infection, and monitor treatment responses. One of these markers is ubiquicidin(29-41) (UBI), a cationic peptide fragment that binds to the bacterial membrane wall and is labeled with gallium-68 (68Ga), a positron emitter radioisotope. The use of UBI in positron emission tomography (PET)/computed tomography (CT) for improved detection of lesions has been receiving considerable attention recently. Herein, we report the first case of 68Ga-UBI PET/CT performed in Brazil. The patient was a 39-year-old woman referred for a scan to confirm a clinical suspicion of chronic osteomyelitis of her fractured left tibia. PET images revealed radiotracer uptake near the posterior contour of the tibial fracture focus and the fixation plate, in the soft tissue around the distal half of the tibia, and in the non-consolidated fracture of the left distal fibula. Surgery for local cleaning was performed, and culture of a specimen collected from the surgical site confirmed the presence of Staphylococcus aureus. In the present case, 68Ga-UBI PET/CT, a non-invasive imaging modality, identified the infection foci in vivo, indicating its potential for clinical use.

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ABSTRACT Molecular imaging markers can be used to differentiate between infection and aseptic inflammation, determine the severity of infection, and monitor treatment responses. One of these markers is ubiquicidin(29-41) (UBI), a cationic peptide fragment that binds to the bacterial membrane wall and is labeled with gallium-68 (68Ga), a positron emitter radioisotope. The use of UBI in positron emission tomography (PET)/computed tomography (CT) for improved detection of lesions has been receiving considerable attention recently. Herein, we report the first case of 68Ga-UBI PET/CT performed in Brazil. The patient was a 39-year-old woman referred for a scan to confirm a clinical suspicion of chronic osteomyelitis of her fractured left tibia. PET images revealed radiotracer uptake near the posterior contour of the tibial fracture focus and the fixation plate, in the soft tissue around the distal half of the tibia, and in the non-consolidated fracture of the left distal fibula. Surgery for local cleaning was performed, and culture of a specimen collected from the surgical site confirmed the presence of Staphylococcus aureus. In the present case, 68Ga-UBI PET/CT, a non-invasive imaging modality, identified the infection foci in vivo, indicating its potential for clinical use.

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Human bacterial infections significantly contribute to the increase in healthcare-related burdens. This scenario drives the study of novel techniques for the early and precise diagnosis of infectious processes. Some alternatives include Nuclear Medicine- and Molecular Imaging-based strategies. However, radiopharmaceuticals that are available for routine assessments are not specific to differentiating infectious from aseptic inflammatory processes. In this context, [68Ga]Ga-DOTA-Ubiquicidin29-41 was synthesized using an automated module and radiochemical; in vivo and in vitro studies were performed. The radiopharmaceutical remained stable in saline (up to 180 min) and in rodent serum (up to 120 min) with radiochemical purities > 99 and 95%, respectively. Partition coefficient and serum protein binding at 60 min were determined (-3.63 ± 0.17 and 44.06 ± 1.88%, respectively). Ex vivo biodistribution, as well as in vivo microPET/CT images in mice, showed rapid blood clearance with renal excretion and reduced uptake in other organs in Staphylococcus aureus-infected animals. Higher uptake was observed in the target as compared to the non-target tissue (p < 0.0001) at 60 min post administration. The presented in-human clinical case demonstrates uptake of the radiopharmaceutical by Staphyloccocus aureus bacteria. These results indicate the potential of [68Ga]Ga-DOTA-Ubiquicidin29-41 as a radiopharmaceutical that can be obtained in a hospital radiopharmacy for the diagnosis of infectious processes using PET/CT.

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ABSTRACT: The presynaptic dopamine transporter (DAT) modulates the uptake of dopamine by regulating its concentration in the central nervous system. We aimed to evaluate the DAT binding potential (DAT-BP) in a sample of healthy Brazilians through technetium-99 metastable TRODAT-1 single-photon emission computed tomography imaging.We selected 126 healthy individuals comprising 72 men and 54 women, aged 18 to 80 years. We conducted semi-quantitative evaluation in transaxial slices, following which we identified the regions of interest in the striatal region using the occipital lobe as a region of non-specific DAT-BP.We found a decrease in DAT-BP in healthy individuals aged over 30 years, culminating in a 42% mean reduction after 80 years. There was no difference in the decrease by age group between the right (linear regression test [R2] linear = 0.466) and left striatum (R2 linear = 0.510). Women presented a higher DAT-BP than men (women: R2 linear = 0.431; men: R2 linear = 0.457); nonetheless, their decrease by age group was equal to that in men.Our study sheds light on important DAT-BP findings in healthy Brazilian subjects. Our results will facilitate understanding of brain illnesses that involve the dopamine system, such as neuropsychiatric disorders.

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In recent years, medical imaging with hybrid techniques has widely accepted and employed in clinical routine. PET/MRI offers significant advantages, including excellent contrast and resolution and reduced ionizing radiation, as compared to well-established PET/CT. Therefore, PET/MRI is a promising modality for oncologic imaging of some regions, such as brain, head and neck, liver and pelvis. This article set out to analyze clinical conditions that could benefit from PET/MRI imaging based on our caseload. The potential of PET/MRI to become the imaging modality of choice for assessment of neurologic and oncologic conditions associated with soft tissues is highlighted. Clinical aspects of PET/MRI and its application to clinical cases are illustrated with examples extracted from the authors' preliminary experience. RESUMO Nos últimos anos, imagens médicas com tecnologias híbridas tornaram-se amplamente aceitas e utilizadas na prática clínica. O PET/RM possui vantagens importantes, incluindo excelentes contrastes e resolução, e menor radiação ionizante, em comparação ao PET/TC. Por isto, é uma modalidade promissora para exames de imagem de pacientes oncológicos, para avaliar o cérebro, cabeça e pescoço, o fígado e a pelve. O objetivo deste artigo foi analisar as situações clínicas que se beneficiariam de exames de PET/RM a partir de uma casuística. Destacamos o potencial desta técnica se tornar o método de imagem de escolha para doenças neurológicas e oncológicas que envolvam partes moles. Os aspectos clínicos de PET/RM e sua aplicação aos casos clínicos são ilustrados com exemplos da experiência inicial dos autores.

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ABSTRACT In recent years, medical imaging with hybrid techniques has widely accepted and employed in clinical routine. PET/MRI offers significant advantages, including excellent contrast and resolution and reduced ionizing radiation, as compared to well-established PET/CT. Therefore, PET/MRI is a promising modality for oncologic imaging of some regions, such as brain, head and neck, liver and pelvis. This article set out to analyze clinical conditions that could benefit from PET/MRI imaging based on our caseload. The potential of PET/MRI to become the imaging modality of choice for assessment of neurologic and oncologic conditions associated with soft tissues is highlighted. Clinical aspects of PET/MRI and its application to clinical cases are illustrated with examples extracted from the authors’ preliminary experience.

RESUMO Nos últimos anos, imagens médicas com tecnologias híbridas tornaram-se amplamente aceitas e utilizadas na prática clínica. O PET/RM possui vantagens importantes, incluindo excelentes contrastes e resolução, e menor radiação ionizante, em comparação ao PET/TC. Por isto, é uma modalidade promissora para exames de imagem de pacientes oncológicos, para avaliar o cérebro, cabeça e pescoço, o fígado e a pelve. O objetivo deste artigo foi analisar as situações clínicas que se beneficiariam de exames de PET/RM a partir de uma casuística. Destacamos o potencial desta técnica se tornar o método de imagem de escolha para doenças neurológicas e oncológicas que envolvam partes moles. Os aspectos clínicos de PET/RM e sua aplicação aos casos clínicos são ilustrados com exemplos da experiência inicial dos autores.

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The liver is the organ most commonly affected by colorectal cancer metastasis. Currently, liver resection is the treatment of choice, but in cases where it is not possible, intensity-modulated radiation therapy is an alternative. We report the case of a 57-year-old woman whose colorectal carcinoma metastasized to the liver. She was referred for implantation of fiducial markers for intensity-modulated radiation therapy planning. PET-CT stands out as an additional tool for distinguishing metabolically active tumor tissue from other tissues, ensuring effective introduction of percutaneous fiducial markers, especially in cases where use of conventional imaging techniques is limited.

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OBJECTIVE: The aim of this study was to assess the occurrence and frequency of increased physiologic uptake of 99mTc-HYNIC-TOC by the uncinate process of the pancreas in SPECT/CT images. METHODS: Forty-six scans of 41 patients were evaluated retrospectively. The uptake of 99mTc-HYNIC-TOC was considered to be physiologic in patients with normal findings at dedicated abdominal CT or MR and lack of neoplastic lesions in clinical follow-ups. The intensity of uncinate process uptake was compared to the uptake of the normal liver. RESULTS: Focal uptake was attributed to the presence of pancreatic NET in 5 patients. Among the 36 patients without any evidence of malignancy in CT, MR and follow-up, 7 (19.4 %) showed increased uptake in the uncinate process. The intensity of uptake was lesser in 3 (8.3 %), similar in 3 and greater than the normal liver in 1 (2.8 %) case. CONCLUSION: Increased 99mTc-HYNIC-TOC uptake occurred in 19.4 % of those subjects without any evidence of neuroendocrine tumor in the uncinate process.

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OBJECTIVE: To describe the Single Photon Emission Microscope (SPEM), a state-of-the-art instrument for small animal SPECT imaging, and characterize its performance presenting typical images of different animal organs. METHODS: SPEM consists of two independent imaging devices based on high resolution scintillators, high sensitivity and resolution Electron-Multiplying CCDs and multi-pinhole collimators. During image acquisition, the mouse is placed in a rotational vertical holder between the imaging devices. Subsequently, an appropriate software tool based on the Maximum Likelihood algorithm iteratively produces the volumetric image. Radiopharmaceuticals for imaging kidneys, heart, thyroid and brain were used. The mice were injected with 74 to 148 MBq/0,3mL and scanned for 40 to 80 minutes, 30 to 60 minutes afterwards. During this procedure, the animals remained under ketamine/xilazine anesthesia. RESULTS: SPEM images of different mouse organs are presented, attesting the imaging capabilities of the instrument. CONCLUSION: SPEM is an innovative technology for small animal SPECT imaging providing high resolution images with appropriate sensitivity for pre-clinical research. Its use with appropriate radiotracers will allow translational investigation of several animal models of human diseases, their pharmacological treatment and the development of potential new therapeutic agents.

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