Perfusion Lung Scans During the Pandemic: COVID-19 Experience in a Large Trauma Hospital

PURPOSE To evaluate the results of perfusion only lung scans and the frequency of necessary addition of the ventilation part of the scans to diagnose acute pulmonary embolism (PE) during Corona Virus Disease of 2019 (COVID 19) pandemic. MATERIAL AND METHODS We retrospectively reviewed perfusion lung scans’ results between April to December, 2020. The images were interpreted by two experienced nuclear medicine physicians as daily routine studies. Ventilation images were performed only if deemed necessary for accurate diagnosis of acute PE. RESULTS A total of 128 lung perfusion scans in 127 patients were included. The scans were interpreted with certainty using the modified PIOPID criteria in 122 patients (95.3%). The results included low probability for acute PE in 110 patients (85.9%), normal in 6 patients (4.7%) and high probability of acute PE in 6 patients (4.7%). Ventilation imaging were performed in 4 patients with high probability, after negative testing for COVID19. The other 2 high probability results were confirmed clinically and with radiologic imaging. Only 6 scans (4.7%) were interpreted as intermediate perfusion scans, two of which due to inability to differentiate old from new perfusion defects in patients with chronic thromboembolic disease. Thus, the true indeterminate results due to the lack of ventilation scan were encountered in only 4 intermediate probability lung scans (3.1%). Thus, the total number of requested ventilation scans was 8 scans (6.2%) when considering both the high and intermediate probability interpretations. Six scans were performed (2 in the intermediate and 4 in the high probability scans). The two ventilation scans performed in the intermediate probability changed the diagnosis to low probability and the four performed in the high probability confirmed the initial interpretation of high probability scans by perfusion only. CONCLUSION The ventilation part of lung scans is required only in a small number of patients for certain interpretation of the result. Perfusion lung scans are sufficient for evaluation of acute PE with certainty in most patients.

Experience with a Perfusion-Only Screening Protocol for Evaluation of Pulmonary Embolism During the COVID-19 Pandemic Surge.

The purpose of this study was to evaluate a pulmonary embolism (PE) perfusion-only screening (POS) protocol introduced during the coronavirus disease 2019 (COVID-19) pandemic surge. Subjects without dense parenchymal lung opacities were studied; those with less than 1 segmental perfusion defect were considered to have no PE, whereas those exhibiting 1 or more defects were indeterminate, mandating additional examinations to determine the final diagnosis. Methods: We analyzed demographic information, clinical data, imaging findings, and follow-up data from the electronic records of COVID-19 patients who underwent lung scintigraphy during the 60-d study period. Results: In total, 53 studies were performed on 17 COVID-19-positive and 36 COVID-19-negative patients. The POS protocol efficiently excluded PE in 79% of cases; the remaining 21%, indeterminate for PE, were generally referred for alternative testing or were directly anticoagulated. In patients with negative POS results, there was a very low mortality before hospital discharge (1/42) and normal results on follow-up studies (6/6). Conclusion: The POS protocol, implemented during the COVID-19 surge, efficiently and safely excluded PE in 79% of patients.

Signs of tracheobronchitis may constitute the principal finding on the lung SPECT/CT images of COVID-19 patients.

BACKGROUND: This study aimed to analyze the rates of tracheobronchitis signs observed on the ventilation scans of COVID-19 patients with shortness of breath, with comparisons to a non-COVID population. METHODS: Lung scintigraphy was collected in 10 such COVID patients, as well as from a non-COVID population investigated outside the epidemic wave period, on a CZT-SPECT/CT system, with ventilation images recorded with 99mTc-labeled Technegas® and perfusion images with 99mTc-labeled albumin macroaggregates. RESULTS: A diffuse tracheobronchial uptake was observed on the ventilation scans from 3 COVID patients (30%), whereas this rate was 3% (3/90) in the non-COVID group (P = 0.013). These 3 patients had no laryngeal extension of Technegas® uptake and limited parenchymal lung abnormalities. Follow-up scintigraphy demonstrated the withdrawal of tracheobronchitis signs in two cases, and the advent of a severe pulmonary embolism in one. CONCLUSION: Signs of tracheobronchitis may constitute the principal finding on lung SPECT/CT images of COVID-19 patients with shortness of breath.