"The sign is named after Antonio Palla (1949-fl.2025), an Italian radiologist, who published his observation in 1983 that approximately 25% of patients with pulmonary embolism had an enlarged right descending pulmonary artery 1."
"The Palla sign is uncommon and has low sensitivity for pulmonary embolism; it was reported in roughly one quarter of patients with confirmed pulmonary embolism in the original series and was absent in many cases 3,4."