Semiquantitative analysis of cerebral [18F]FDG-PET uptake in pediatric patients.

BACKGROUND: Glycolytic metabolism in the brain of pediatric patients, imaged with [18F]  fluorodeoxyglucose-positron emission tomography (FDG-PET) is incompletely characterized. OBJECTIVE: The purpose of the current study was to characterize [18F]FDG-PET brain uptake in a large sample of pediatric patients with non-central nervous system diseases as an alternative to healthy subjects to evaluate changes at different pediatric ages. MATERIALS AND METHODS: Seven hundred ninety-five [18F]FDG-PET examinations from children < 18 years of age without central nervous system diseases were included. Each brain image was spatially normalized, and the standardized uptake value (SUV) was obtained. The SUV and the SUV relative to different pseudo-references were explored as a function of age. RESULTS: At all evaluated ages, the occipital lobe showed the highest [18F]FDG uptake (0.27 ± 0.04 SUV/year), while the parietal lobe and brainstem had the lowest uptake (0.17 ± 0.02 SUV/year, for both regions). An increase [18F]FDG uptake was found for all brain regions until 12 years old, while no significant uptake differences were found between ages 13 (SUV = 5.39) to 17 years old (SUV = 5.52) (P < 0.0001 for the whole brain). A sex dependence was found in the SUVmean for the whole brain during adolescence (SUV 5.04-5.25 for males, 5.68-5.74 for females, P = 0.0264). Asymmetries in [18F]FDG uptake were found in the temporal and central regions during infancy. CONCLUSIONS: Brain glycolytic metabolism of [18F]FDG, measured through the SUVmean, increased with age until early adolescence (< 13 years old), showing differences across brain regions. Age, sex, and brain region influence [18F]FDG uptake, with significant hemispheric asymmetries for temporal and central regions.

Signo de "doble corteza" visualizado en corregistro 18F-FDG PET/RM en un paciente con heterotopia subcortical en banda / "Double Cortex" Sign Visualized in 18F-FDG PET / MRI Coregistration in a Patient with Band Subcortical Heterotopia

Resumen La heterotopia subcortical en banda (HSB) se refiere a la presencia de bandas lisas bilaterales de sustancia gris cerebral ubicadas en la sustancia blanca subcortical. La presentación clínica es variable, con cuadros que incluyen discapacidad intelectual, crisis epilépticas y trastornos de conducta muy variados, lo que hace complejo su diagnóstico. Presentamos el caso de un varón de 20 años con largo historial de epilepsia refractaria a tratamiento, remitido a nuestra unidad para un estudio de tomografía por emisión de positrones/tomografía computada (PET/CT) con 18F-fluorodesoxiglucos (18F-FDG) para la búsqueda del foco epileptógeno. Adicionalmente, se realizó un corregistro de PET con un estudio de resonancia magnética (RM) de otra institución, observando el signo de doble corteza cerebral por RM y PET/CT, visualizando característicamente un patrón hipermetabólico en las zonas de heterotopia subcortical en banda.

Abstract Subcortical band heterotopia (HSB) refers to the presence of smooth bilateral bands of gray matter located in the subcortical white matter. Clinical presentation is widely variable, the presentation includes intellectual disability, epileptic seizures and varied conduct disorders, making a complex diagnosis. We present a case of a 20-year-old male with a long history of treatment-refractory epilepsy referred to our center for a 18F-FDG (18F-fluorodeoxyglucose) PET/CT (Positron Emission Tomography/Computed Tomography), to search for the epileptogenic focus. Additionally, a registration was carried out with another magnetic resonance imaging study (MRI), where the sign of double cerebral cortex was documented by MRI and PET/CT, visualized as a hypermetabolic pattern in subcortical band heterotopia.

13N-Ammonia myocardial blood flow quantitation in patient with aneurismal coronary artery disease.

Aneurysmal coronary artery disease includes coronary artery aneurysms and ectasia; this condition has been associated with poor long-term outcomes. Few studies have explored myocardial blood flow 13N-ammonia PET/CT MPI added value. We present a 45-year-old man who came to the emergency department with chest pain. After a physical examination and laboratory studies, he was diagnosed with very high-risk unstable angina and referred to the catheterization laboratory. Coronary angiography showed the culprit lesion in the LCx and was treated by angioplasty and stent. LAD was found with coronary artery ectasia (TIMI 2 flow grade) and the RCA with aneurysmal disease in the proximal and middle segments (TIMI 3 flow grade). Medical treatment was decided for these findings and the patient was discharged. Two weeks later, we performed a 13N-ammonia PET/CT MPI founding apical, inferior, and inferoseptal severe ischemia, and reduced hyperemic coronary blood flow and coronary flow reserve in the RCA territory. Flow was normal in the LAD territory. Although coronary angiography remains the gold standard for evaluating these coronary abnormalities, it does not show the physiological compromise. Therefore 13N-ammonia PET/CT MPI should be performed as a complementary noninvasive imaging approach.

A Comparison of 18F-PSMA-1007 and 64Cu-PSMA in 2 Patients With Metastatic Prostate Cancer.

ABSTRACT: 18F-prostate-specific membrane antigen (PSMA) 1007 is one of the most promising radiotracers for PET imaging in prostate cancer, minimal urinary clearance, and higher spatial resolution, which are the most outstanding features. PSMA can also be labeled with 64Cu, offering a longer half-life and different resolution imaging. We present images of metastatic prostate cancer in two patients, where 64Cu-PSMA PET/CT was performed one day after 18F-PSMA-1007 PET/CT. In the two patients, both radiotracers provided high image quality and a similar range of detection for metastatic lesions.

Semiautomatic assessment of whole-body tumor burden with 18F-PSMA-1007 in biochemical recurrent prostate cancer.

OBJECTIVE: The aim of the study was to evaluate the 18F-PSMA-1007 PET/computed tomography (CT) semiautomatic volumetric parameters to assess the whole-body tumor burden and its correlation with prostate-specific antigen (PSA) and Gleason score in patients with biochemically recurrent prostate cancer (PCa). MATERIALS AND METHODS: A total of 110 patients referred for 18F-PSMA-1007 PET/CT due to biochemical recurrence were retrospectively analyzed. Whole-body total lesion prostate-specific membrane antigen (wbTl-PSMA) and whole-body PSMA-derived tumor volume (wbPSMA-TV) metrics on 18F-PSMA-1007 were obtained semiautomatically in dedicated software. A Spearman test was performed to explore the correlation of volumetric imaging parameters with PSA levels and Gleason score. To analyze the association between volumetric measures and PSA subgroups, we used a Kruskal-Wallis test and a Dunn's test to identify each group causing an observed difference. RESULTS: A total of 492 metastatic lesions were analyzed, and a significant correlation was found between wbTL-PSMA (R = 0.63, P < 0.0001) and wbPSMA-TV (R = 0.49, P < 0.0001) with serum PSA. A statistically significant difference with wbTL-PSMA was found in patients with a PSA less than or equal 0.5 ng/ml and PSA in the range of 0.51-1.0 ng/ml. CONCLUSION: 18F-PSMA-1007 PSMA volumetric parameters can provide a quantitative imaging biomarker for whole-body tumor burden.

[68Ga]Ga-iPSMA-Lys3-Bombesin: Biokinetics, dosimetry and first patient PET/CT imaging.

BACKGROUND: The prostate-specific membrane antigen (PSMA) and the gastrin-releasing peptide receptor (GRPR) are overexpressed in prostate cancer (PCa). In preclinical studies, the iPSMA-Lys3-Bombesin (iPSMA-BN) heterodimeric ligand has shown a suitable affinity for PSMA and GRPR. This research aimed to assess the biokinetics and radiation dosimetry of [68Ga]Ga-iPSMA-BN in four healthy volunteers based on biodistribution data obtained from whole-body PET/CT studies, as well as to visualize the [68Ga]Ga-iPSMA-BN tumor uptake in a patient with PCa. METHODS: PET/CT images acquired at 5 min, 0.5, 1, and 2 h after radiotracer administration (124.5 ± 2.1 MBq) were corrected for attenuation, scattering, dead-time, and decay. The activity in the segmented volumes of interest (VOIs) in each source organ at different times was adjusted to mono- and bi-exponential biokinetic models (A(t)VOI), from which the total disintegrations (N) were calculated to assess the internal radiation doses by using the OLINDA V1.1 code. RESULTS: Images from the patient showed an evident uptake by the metastasis (SUVmax of 4.7) and by the organs expressing GRPR (pancreas) and PSMA (salivary glands). The average effective dose was 2.70 ± 0.05 mSv, which was like those known for most of the 68Ga studies, making [68Ga]Ga-iPSMA-BN a promising dual-target PET imaging radiotracer for PCa. CONCLUSIONS: [68Ga]Ga-iPSMA-BN, capable of detecting both PSMA and GRPR with suitable biokinetics and dosimetric patterns, could be a potential complementary diagnostic tool for the improvement of prostate cancer PET imaging.

Utilidad de la tomografía por emisión de positrones/ tomografía computada (PET/CT) en pacientes con diagnóstico de meduloblastoma / Usefulness of Positron Emission Tomography/Computed Tomography (PET/CT) in Patients Diagnosed with Medulloblastoma

Resumen: La tomografía por emisión de positrones/tomografía computada (PET/CT) por sus siglas en inglés, es una modalidad de imagen única que proporciona evidencia in vivo de actividades tanto bioquímicas como fisiológicas en diferentes órganos y estructuras del cuerpo. El meduloblastoma es el tumor maligno más frecuente del sistema nervioso central (SNC) en pacientes pediátricos, por este motivo el PET/CT juega un papel importante en el manejo de estos pacientes ya que proporciona información sobre el grado y extensión del tumor, así como a determinar el sitio adecuado para la toma de biopsia, valorar la respuesta al tratamiento y determinar el pronóstico del paciente. Existen diferentes radiofármacos para la evaluación de los tumores de sistema nervioso central, pero se ha estudiado que el 18F-FDG (flúor-2-fluoro-2-desoxi-D-glucosa) y el 68Ga-DOTA-NOC (68Ga-DOTA0-1NaI3-octreotide) nos ayudan a evaluar y dar seguimiento a pacientes con diagnóstico de meduloblastoma. El meduloblastoma tiene una sobreexpresión de transportadores de glucosa, principalmente tipo 1 y sobreexpresión de receptores de somatostatina predominantemente tipo 2, lo cual permite que exista una gran afinidad por estos radiofármacos.

Abstract: PET/CT (positron emission tomography/computed tomography, for its acronym in English) is a unique imaging method that provides in vivo evidence of both biochemical and physiological activities of the brain, spinal cord and tumors that involve these structures. Medulloblastoma is the most common malignant tumor of the central nervous system (CNS) in pediatric patients, so PET/CT plays an important role as it provides information on the grade and extent of the tumor, as well as to determine the appropriate site for the biopsy, assessing the response to the treatment and the patient's prognosis. There are different radiopharmaceuticals for the evaluation of central nervous system tumors, but 18F FDG (Fluor-2-fluoro-2-desoxy-D-glucose) and 68Ga-DOTA-NOC (68Ga-DOTA0-1NaI3-octreotide) have been studied to help us evaluate and follow up patients diagnosed with medulloblastoma. Medulloblastoma has an overexpression of glucose transporters, mainly type 1, and an overexpression of predominantly type 2 somatostatin receptors, which allows a high affinity for these radiopharmaceuticals.

Quantitative Analysis of [18F]FFMZ and [18F]FDG PET Studies in the Localization of Seizure Onset Zone in Drug-Resistant Temporal Lobe Epilepsy.

BACKGROUND: Positron emission tomography (PET) imaging in epilepsy is an in vivo technique that allows the localization of a possible seizure onset zone (SOZ) during the interictal period. Stereo-electro-encephalography (SEEG) is the gold standard to define the SOZ. The objective of this research was to evaluate the accuracy of PET imaging in localizing the site of SOZ compared with SEEG. METHODS: Seven patients with refractory temporal lobe epilepsy (Ep) and 2 healthy controls (HC) underwent 2 PET scans, one with 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) and another with 2'-[18F]fluoroflumazenil (FFMZ), acquired 1 day apart. FDG was acquired for 10 min (static scan) 1 h after administration. An FFMZ scan was acquired for 60 min from radiopharmaceutical administration in a dynamic mode. Each brain PET image was segmented using a standard template implemented in PMOD 3.8. The pons was used as the reference region for modeling of the nondisplaceable binding potential (BPND)for FFMZ, and to obtain uptake ratios for FDG. SEEG studies of patients were performed as a part of their surgical evaluation to define the SOZ. RESULTS: Well-defined differences between HC and Ep were found with both radiopharmaceuticals, showing the utility to identify abnormal brain regions using quantitative PET imaging. Lateralization of the SOZ findings by PET (lower uptake/binding in a specific brain hemisphere) matched in 86% for FFMZ and 71% for FDG with SEEG data. CONCLUSION: Quantitative PET imaging is an excellent complementary tool that matches reasonably well with SEEG to define SOZ in presurgical evaluation.

Estado actual y perspectivas de la imagen molecular PET en México.

Positron-emission tomography (PET) is a medical diagnostic technique by means of which functional images are obtained by recording the spatio-temporal biodistribution of specific radiopharmaceuticals targeted at specific molecular objectives, which provides biochemical information at the molecular level. Early in the first decade of this 21st century, the Faculty of Medicine of the National Autonomous University of Mexico acquired the technology to implement this diagnostic technique in Mexico, thus becoming a pioneer in PET applications in the country and in Latin America. Almost two decades after its implementation in Mexico, PET has become an essential tool in medical clinics. This article describes the background, current state and perspectives of PET molecular imaging in Mexico, and the impact it has had on the management of patients with oncological, neurological and heart diseases.

La tomografía por emisión de positrones (PET) es una técnica de diagnóstico médico mediante la cual se obtienen imágenes funcionales a partir de registrar la biodistribución espacio-temporal de radiofármacos específicos dirigidos a blancos moleculares específicos, proveyendo información bioquímica a nivel molecular. A principios de la primera década de este siglo XXI, la Facultad de Medicina de la Universidad Nacional Autónoma de México implementó esta técnica de diagnóstico en México, convirtiéndose en pionera en aplicaciones PET en el país y Latinoamérica. Casi dos décadas después, la PET se ha convertido en una herramienta esencial en la clínica médica. En este artículo se describen los antecedentes, el estado actual, las perspectivas de la imagen molecular PET en México y el impacto que ha tenido en el manejo de pacientes con enfermedades oncológicas, neurológicas y cardiológicas.

Estado actual y perspectivas de la imagen molecular PET en México / Current status and perspectives of PET molecular imaging in Mexico

Resumen La tomografía por emisión de positrones (PET) es una técnica de diagnóstico médico mediante la cual se obtienen imágenes funcionales a partir de registrar la biodistribución espacio-temporal de radiofármacos específicos dirigidos a blancos moleculares específicos, proveyendo información bioquímica a nivel molecular. A principios de la primera década de este siglo XXI, la Facultad de Medicina de la Universidad Nacional Autónoma de México implementó esta técnica de diagnóstico en México, convirtiéndose en pionera en aplicaciones PET en el país y Latinoamérica. Casi dos décadas después, la PET se ha convertido en una herramienta esencial en la clínica médica. En este artículo se describen los antecedentes, el estado actual, las perspectivas de la imagen molecular PET en México y el impacto que ha tenido en el manejo de pacientes con enfermedades oncológicas, neurológicas y cardiológicas.

Abstract Positron-emission tomography (PET) is a medical diagnostic technique by means of which functional images are obtained by recording the spatio-temporal biodistribution of specific radiopharmaceuticals targeted at specific molecular objectives, which provides biochemical information at the molecular level. Early in the first decade of this 21st century, the Faculty of Medicine of the National Autonomous University of Mexico acquired the technology to implement this diagnostic technique in Mexico, thus becoming a pioneer in PET applications in the country and in Latin America. Almost two decades after its implementation in Mexico, PET has become an essential tool in medical clinics. This article describes the background, current state and perspectives of PET molecular imaging in Mexico, and the impact it has had on the management of patients with oncological, neurological and heart diseases.