18F-FDG PET/CT has been proven successful in evaluating lung inflammation and monitoring treatment effects in patients suffering from post-COVID-19 lung disease. Presented at the Society of Nuclear Medicine and Molecular Imaging 2022 Annual Meeting, this study shows for the first time that residual COVID-19 symptoms, such as cough and breathlessness, can be attributed to the load of ongoing inflammation in the lungs.
Respiratory complications are a common and critical effect of severe COVID-19 infection. At least one-third of patients hospitalized with COVID-19 are affected by respiratory symptoms. Several of these patients suffer from post-COVID-19 lung disease and require supplemental oxygen even after testing negative for COVID-19.
“During the pandemic, there was no standard modality to assess residual lung inflammation. It was difficult to gauge the extent and severity of disease even in recovering patients, and hence challenging to start appropriate treatment,” said Yogita Khandelwal, MBBS, a resident doctor at the Sanjay Gandhi Postgraduate Institute of Medical Sciences in Lucknow, Uttar Pradesh, India.
In the study, researchers utilized 18F-FDG PET/CT to assess the metabolic activity of lung lesions and to evaluate the effect of steroids and antifibrotic drugs in treating post-COVID-19 lung disease. Baseline 18F-FDG PET/CT was performed to evaluate the residual inflammatory activity in the lungs. Patients with inflammatory activities received steroid and antifibrotic treatment, and a follow-up 18F-FDG PET/CT scan was performed after six to 12 weeks to evaluate treatment response and assess residual fibrosis.
Of the 25 patients included in the study, all initially showed metabolically active lesions in both lungs. Metabolically active mediastinal lymph nodes were also noted in more than half of the patients. After treatment with steroids and antifibrotic drugs, there was a significant decrease in the number, size and FDG-avidity of the previously seen lung lesions among all patients.
“18F-FDG PET/CT proved to be a sensitive tool for monitoring ongoing inflammation and its management,” noted Khandelwal. “Molecular markers identified by 18F-FDG PET/CT can reveal the triggers and sustenance mechanism of inflammation, In the future, this could contribute to the development of new drugs and better management strategies.”
PHOTO CAPTION: A 71-year-old male was diagnosed with COVID-19 in October 2020. He was treated and discharged from the hospital. He was readmitted to the hospital for respiratory failure in January 2021. He underwent 18F-FDG PET/CT. (A) MIP whole-body image and axial fused PET/CT show FDG-avid (SUV max – 12.7) consolidation in the right lung (red arrow). Non-tracer-avid changes are noted in both lungs on CT. FDG-avid mediastinal lymph nodes (SUV max – 4.4) (yellow arrow) were also noted. The patient was given steroids and Pirfenidone for two months. He showed significant improvement in symptoms with no O2 requirement. (B) Follow-up PET/CT reveals complete resolution of the lung lesion and non-avid residual fibrotic changes in both lungs (red arrow). Mediastinal lymph nodes also show a decrease in avidity (SUV max – 2.5).
Abstract 1210. “A prospective study to investigate the implementation of semiquantitative inflammatory load in post-COVID-19 lung disease (PCLD) to strategize therapy,” Yogita Khandelwal, Manish Ora, Prakash Singh, Bela Jain, Sonam Suman, Alok Nath, Ajmal Khan, Manish Dixit, and Sanjay Gambhir, SGPGIMS, Lucknow, Uttar Pradesh, India.