ABSTRACT
Aim/Introduction: Although pulmonary findings of COVID-19 on PET/CT have been previously described, a comprehensive metabolic characterization of diagnostic lung parenchyma changes of COVID-19 pneumonia is still lacking. Our purpose is to evaluate the metabolic uptake of different tomographic signs observed in patients with incidental structural findings suggesting COVID-19 pneumonia through 18F-FDG PET/CT. Material(s) and Method(s): We retrospectively analyzed 596 PET/CT studies performed from February 21, 2020 to April 17, 2020. After excluding 37 scans (PET with non-18F-FDG tracers and brain studies), we analyzed the metabolic activity of several individual structural changes integrated and beyond CO-RADS score through SUVmax of multimodal studies with18F-FDG. Result(s): 43 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, nonspecific CO-RADS categories (6.1+/-3.0 vs. 3.6+/-2.1, p=0.004). Groundglass opacities, bilaterality, consolidations, patchy distribution and crazy paving pattern were associated with higher SUVmax values in patients with CO-RADS 5-6 scores (p-values of 0.01, 0.02, 0,01, 0.002 and 0.01, respectively). 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 aimed to confirm or discard the structural diagnosis of COVID-19 pneumonia showed an AUC of 0.77 (standard error=0.072, p=0.003). Conclusion(s): Multimodal18F-FDG PET/CT is a useful tool during the incidental detection of COVID-19 pneumonia in patients referred for standard oncological and nononcological indications (43/559;7.7%). CT findings characteristic of COVID-19 pneumonia, specifically CO-RADS 5-6, were associated with higher SUVmax.
ABSTRACT
Aim/Introduction: PET-CT with diagnostic CT with intravenous administration of iodinated contrast allows increasing the diagnostic efficacy of the studies by combining in a single exploration the anatomical information of CT and the metabolic information of PET. A small percentage of these patients will show incidental findings that require urgent management of the patient, taking into account that most of them are oncologic patients. Otherwise, SARSCoV-2 has caused the coronavirus disease 2019 (COVID-19) throughout the world turning into a public health emergency. PET-CT studies of some asymptomatic cancer patients showed lung involvement suggestive of COVID-19 pneumonia. Our aim is to retrospectively analyze patients who required urgent medical attention when they attended for a PET-CT scan during the years 2020 and 2021. Material(s) and Method(s): We did a retrospective review of the reports of 9057 PET-CT scans performed in our hospital during the years 2020 and 2021 (8884 with18F-FDG, 5068Ga-DOTATOC, 10618F-Fluorocholine, 1418F-DCFPyL and 318F-FDOPA). From those, 8499 (93,8%) were oncologic patients. Patients who were referred to the Emergency Department from Nuclear Medicine due to hyperglycemia or incidental findings in the PET-CT scan requiring urgent medical attention were selected. The studies were acquired after intravenous injection of radiotracer, in a PET-CT camera (multidetector CT). Most studies were performed with intravenous (i.v.) iodinated contrast, acquiring a chest sequence in inspiration and arterial phase and another full body sequence in portal phase. Each study was evaluated by an expert nuclear medicine physician and a radiologist. A single report was subsequently drawn up. Result(s): 143 patients (1.57%) with an incidental finding requiring urgent attention were identified. Twelve of these patients (8,39%) were referred to the Emergency Department for the presence of hyperglycemia greater than 350mg/dl so that PET-CT scan could not be performed. The most frequent incidental findings in PETCT images were: pulmonary thromboembolism (34 patients;23.8%), venous thrombosis (25;17.5%) and pulmonary infiltrates suggestive of COVID 19 disease (15;10.5%). The most frequent pathologies among the patients studied were lung cancer (30 patients), breast cancer (28 patients) and head and neck cancers (15 patients). Conclusion(s): PET-CT has proven to be useful in the incidental finding of medical pathologies that require urgent medical attention. Likewise, the performance of a directed chest CT with iodinated contrast within the PET-CT protocol has contributed to the diagnosis of pulmonary thromboembolism, a relatively frequent finding in oncologic patients.