Caracterización metabólica de los cambios pulmonares estructurales en pacientes con hallazgos incidentales sugestivos de neumonía por COVID-19 en estudios 18F-FDG PET/CT. Perspectivas fisiopatológicas de imágenes multimodales obtenidas durante la pandemia / Metabolic characterization of structural lung changes in patients with findings suggestive of incidental COVID-19 pneumonia on 18F-FDG PET/CT: Pathophysiological insights from multimodal images obtained during the pandemic

Objetivo Evaluar la captación metabólica de diferentes signos tomográficos observados en pacientes con hallazgos estructurales incidentales sugestivos de neumonía por COVID-19 mediante PET/TC con 18F-FDG. Material y métodos Se analizaron retrospectivamente 596 estudios PET/TC realizados desde el 21 de febrero de 2020 hasta el 17 de abril de 2020. Tras excluir 37 exploraciones (trazadores PET diferentes a la 18F-FDG y estudios cerebrales), se evaluó la actividad metabólica de varios cambios estructurales integrados en la puntuación CO-RADS mediante el SUVmáx de estudios multimodales con 18F-FDG. Resultados Se incluyeron 43 pacientes r COVID-19 en la 18F-FDG PET/TC (edad media: 68±12,3 años, 22 varones). Los valores de SUVmáx fueron mayores en los pacientes con categorías CO-RADS 5-6 respecto a los de categorías CO-RADS inferiores (6,1±3,0 vs. 3,6±2,1, p=0,004). En los pacientes con CO-RADS 5-6, las opacidades en vidrio deslustrado, la bilateralidad y las consolidaciones mostraron valores de SUVmáx más elevados (valores de la p de 0,01, 0,02 y 0,01, respectivamente). La distribución parcheada y el patrón crazy paving también se asociaron a valores de SUVmáx más elevados (valores de p de 0,002 y 0,01). Tras el análisis multivariable, el SUVmáx se asoció significativamente con un diagnóstico estructural positivo de neumonía por COVID-19 (odds ratio=0,63, intervalo de confianza del 95%=0,41-0,90; p=0,02). La curva ROC del modelo de regresión destinado a confirmar o descartar el diagnóstico estructural de neumonía por COVID-19 mostró un AUC de 0,77 (error estándar=0,072; p=0,003). Conclusiones En aquellos pacientes remitidos a 18F-FDG PET/TC por indicaciones oncológicas y no oncológicas estándar (43/559; 7,7%) durante la pandemia, la obtención de imágenes multimodales es una herramienta útil durante la detección incidental de neumonía (AU)

Purpose To evaluate the metabolic uptake of different tomographic signs observed in patients with incidental structural findings suggestive of COVID-19 pneumonia through 18F-FDG PET/CT. Material and methods We retrospectively analyzed 596 PET/CT studies performed from February 21, 2020 to April 17, 2020. After excluding 37 scans (non-18F-FDG PET tracers and brain studies), we analyzed the metabolic activity of several structural changes integrated in the CO-RADS score using the SUVmax of multimodal studies with 18F-FDG. Results Forty-three patients with 18F-FDG PET/CT findings suggestive of COVID-19 pneumonia were included (mean age: 68±12.3 years, 22 male). SUVmax values were higher in patients with CO-RADS categories 5–6 than in those with lower CO-RADS categories (6.1±3.0 vs. 3.6±2.1, p=0.004). In patients with CO-RADS 5–6, ground-glass opacities, bilaterality and consolidations exhibited higher SUVmax values (p-values of 0.01, 0.02 and 0.01, respectively). Patchy distribution and crazy paving pattern were also associated with higher SUVmax (p-values of 0.002 and 0.01). After multivariate analysis, SUVmax was significantly associated with a positive structural diagnosis of COVID-19 pneumonia (odds ratio=0.63, 95% confidence interval=0.41–0.90; p=0.02). The ROC curve of the regression model intended to confirm or rule out the structural diagnosis of COVID-19 pneumonia showed an AUC of 0.77 (standard error=0.072, p=0.003). Conclusions In those patients referred for standard oncologic and non-oncologic indications (43/559; 7.7%) during pandemic, imaging with 18F-FDG PET/CT is a useful tool during incidental detection of COVID-19 pneumonia. Several CT findings characteristic of COVID-19 pneumonia, specifically those included in diagnostic CO-RADS scores (5–6), were associated with higher SUVmax values (AU)

Metabolic characterization of structural lung changes in patients with findings suggestive of incidental COVID-19 pneumonia on 18F-FDG PET/CT. Pathophysiological insights from multimodal images obtained during the pandemic.

PURPOSE: To evaluate the metabolic uptake of different tomographic signs observed in patients with incidental structural findings suggestive of COVID-19 pneumonia through 18F-FDG PET/CT. MATERIALS AND METHODS: We retrospectively analyzed 596 PET/CT studies performed from February 21, 2020 to April 17, 2020. After excluding 37 scans (non-18F-FDG PET tracers and brain studies), we analyzed the metabolic activity of several structural changes integrated in the CO-RADS score using the SUVmax of multimodal studies with 18F-FDG. RESULTS: Forty-three patients with 18F-FDG PET/CT findings suggestive of COVID-19 pneumonia were included (mean age: 68±12.3 years, 22 male). SUVmax values were higher in patients with CO-RADS categories 5-6 than in those with lower CO-RADS categories (6.1±3.0 vs. 3.6±2.1, p=0.004). In patients with CO-RADS 5-6, ground-glass opacities, bilaterality and consolidations exhibited higher SUVmax values (p-values of 0.01, 0.02 and 0.01, respectively). Patchy distribution and crazy paving pattern were also associated with higher SUVmax (p-values of 0.002 and 0.01). After multivariate analysis, SUVmax was significantly associated with a positive structural diagnosis of COVID-19 pneumonia (odds ratio=0.63, 95% confidence interval=0.41-0.90; p=0.02). The ROC curve of the regression model intended to confirm or rule out the structural diagnosis of COVID-19 pneumonia showed an AUC of 0.77 (standard error=0.072, p=0.003). CONCLUSIONS: In those patients referred for standard oncologic and non-oncologic indications (43/559; 7.7%) during pandemic, imaging with 18F-FDG PET/CT is a useful tool during incidental detection of COVID-19 pneumonia. Several CT findings characteristic of COVID-19 pneumonia, specifically those included in diagnostic CO-RADS scores (5-6), were associated with higher SUVmax values.

Relevance of quantification in brain PET studies with 18F-FDG. / Relevancia de la cuantificación en los estudios PET cerebrales con 18F-FDG.

The inclusion of 18F-FDG PET as a biomarker in the diagnostic criteria of neurodegenerative diseases and its indication in the presurgical assessment for drug-resistant epilepsies allow to improve specificity of these diagnosis. The traditional interpretation of neurological PET studies has been performed qualitatively, although in the last decade, several quantitative evaluation methods have emerged. This technical development has become relevant in clinical practice, improving specificity, reproducibility and reducing the interrater reliability derived from visual analysis. In this article we update/review the main imaging processing techniques currently used. This may allow the Nuclear Medicine physician to know their advantages and disadvantages when including these procedures in daily clinical practice.

18F-FDG PET/CT and functional MRI in a case of crossed logopenic primary progressive aphasia. / 18F-FDG PET/TC y RM funcional en un caso de afasia progresiva primaria logopénica cruzada.

Primary progressive aphasia is a clinical syndrome caused by a neurodegeneration of areas and neural networks involved in language, usually in the left hemisphere. The term "crossed aphasia" denotes an acquired language dysfunction caused by a lesion in the hemisphere ipsilateral to the dominant hand. A case is presented on a 75-year-old right-handed woman with a logopenic variant of primary progressive aphasia with word-finding difficulties of 2 years onset. The 18F-FDG PET/CT showed right temporoparietal hypometabolism. A functional MRI scan was performed during a verb naming task in order to characterise language lateralisation patterns. A similar activation pattern was observed in both hemispheres, with less activation than expected in bilateral inferior frontal gyrus. These findings support that logopenic variant of primary progressive aphasia should not be considered as a neurodegeneration starting in the left brain hemisphere, but as a syndrome characterised by asymmetric neurodegeneration of brain regions and neural networks involved in language.

Breslow thickness and (18)F-FDG PET-CT result in initial staging of cutaneous melanoma: Can a cut-off point be established?

AIM: To establish a Breslow Thickness (BT) cut-off point for indication of PET-CT of cutaneous melanoma in early stages and evaluate its prognostic value. MATERIAL AND METHODS: Retrospective analysis of 347 PET-CT studies with diagnosis of melanoma, of which 108 were performed for initial staging. Thirty-one patients were excluded, and a final sample of 77 patients remained. A ROC curve analysis was performed to establish an optimal cut-off point. A survival analysis was performed, considering death assignable to melanoma as the main event, for the evaluation of its prognostic value. RESULTS: Forty-seven (61.04%) of all 77 patients selected were men, and 11 (14.29%) had a positive PET-CT result. Mean age was 65.17±15.00 years. The median BT in patients with a negative PET-CT result was 2.75 mm (IQR 1.83-4.50) and in the positive group 6.25 mm (IQR 5.40-7.50) (P=.0013). In the ROC curve analysis (AUC 0.804, SE 0.054), an optimal value of 5 mm BT with the following values was obtained: sensitivity 90.91%, specificity 78.79%, negative predictive value (NPV) 98.1%, positive predictive value (PPV) 41.7%, diagnostic OR 37.1, and accuracy 80.52%. Mean follow-up was 18.66±14,35 months, detecting 2/53 (3.77%) deaths in the BT<5 mm group, and 7/24 (29.17%) in the BT≥5 mm group. Survival curves between both groups were significantly different (P=.0013). CONCLUSIONS: A 5 mm cut-off point correctly distinguishes those patients with positive PET-CT from those with negative results in the early stages of cutaneous melanoma; therefore it could be included in initial staging of this subgroup of patients.

Topography of primitive reflexes in dementia: an F-18 fluorodeoxyglucose positron emission tomography study.

BACKGROUND AND PURPOSE: Although primitive reflexes (PRs) are inhibited during the first years of childhood, they may reappear with brain injury. PRs have been linked to frontal lobe dysfunction, but their precise topography has not yet been defined. The purpose of this study was to map which regions of the brain display a reduced glucose metabolism in patients with cognitive impairment and PRs. METHODS: A prospective study was conducted to evaluate PRs in a group of patients assessed due to suspected cognitive decline. Neurological and neuropsychological examinations and (18) F-fluorodeoxyglucose positron emission tomography fused with computerized tomography were performed. Voxel-based brain mapping analysis by means of statistical parametric mapping was used to compare patients with and without PRs. RESULTS: The study included 99 patients (33 diagnosed with Alzheimer's disease, 33 on the frontotemporal dementia spectrum and 33 with other diagnoses). Mean age was 71 ± 9.7 years; time since symptom onset was 3.6 ± 2.9 years. At least one PR was observed in 43 cases (43.4% of the whole sample; 48.5% in the Alzheimer disease group, 63.6% in frontotemporal dementia and 18.2% in the group with other diagnoses). The group of patients with PRs exhibited a decreased cerebral metabolism in the bilateral superior frontal gyri (Brodmann area 6), bilateral putamina and thalami. CONCLUSIONS: The presence of PRs was associated with hypometabolism at the superior frontal gyrus and putamen. This suggests that dysfunction in the corticostriatal motor circuit (supplementary motor area-putamen-thalamus) may constitute the anatomical basis of the recurrence of PRs.

Clinical relevance of incidental finding of focal uptakes in the colon during 18F-FDG PET/CT studies in oncology patients without known colorectal carcinoma and evaluation of the impact on management.

AIMS: To assess the significance and the impact of focal FDG uptake in the colon in oncology patients without known colorectal carcinoma. MATERIALS AND METHODS: A retrospective study was undertaken on 2,220 (18)F-FDG PET/CT studies carried out consecutively in the Nuclear Medicine Department in our hospital from 2 December 2008 to 31 May 2010. Inclusion criteria were patients with abnormal (18)F-FDG uptake in colorectal area that could not be explained (or not previously known) by their clinical histories. Patients previously diagnosed with colorectal carcinoma were excluded. A total of 86 patients (57 male, average age 63.4, range 46-85) were finally included. Colonoscopy with biopsy was established as a reference test. The impact of these findings on the diagnostic-therapeutic management in these patients was evaluated. RESULTS: A colonoscopy was performed in 54 of the 86 patients, this examination not having been done up-to-date in the remaining 32 patients. Biopsy was obtained in 43 lesions of the 54 patient in whom a colonoscopy was performed. Colon disease was detected in 49 of these 54 patients, obtaining 54 FDG incidental foci which corresponded to 10 previously unsuspected primary colorectal carcinoma, 3 metastases, 27 adenomatous polyps with different degrees of dysplasia and 14 inflammatory processes. In the remaining 5 patients, the colonoscopy was normal. PET/CT modified the diagnostic and treatment management in most of the patients (49/54, that is 91%). CONCLUSIONS: These results confirm the need to determine the cause of abnormal (18)F-FDG colorectal uptakes in the PET/CT studies by using colonoscopy and biopsy. This approach allows for the detection and early treatment of malignant and premalignant lesions.