Demystifying Imaging Patterns of Substance Abuse-Related Lung Injury (SARLI)

Recreational substance abuse causes a broad spectrum of acute and chronic pulmonary injuries through inhalation and intravenous injection. Imaging findings often overlap with infection, pulmonary edema, and other inflammatory lung diseases, particularly when an exposure history is unavailable. This review discusses the mechanisms and characteristic CT imaging patterns of substance abuse-related lung injury (SARLI). Crack lung is an acute pulmonary toxicity syndrome occurring within 48 hours of crack cocaine inhalation and manifests as diffuse bilateral ground-glass opacities with patchy consolidations, or a crazy-paving pattern related to pulmonary edema, diffuse alveolar damage, or alveolar hemorrhage. Cannabis smoking is associated with upper-lobe-predominant paraseptal emphysema, apical bullae, and airway inflammation. E-cigarette or vaping product use-associated lung injury is a diagnosis of exclusion and requires vaping exposure within 90 days prior to abnormal pulmonary imaging for establishing the diagnosis. It most commonly demonstrates an organizing pneumonia pattern, although diffuse alveolar damage and alveolar hemorrhage may occur. Intravenous injection of crushed oral medications can cause excipient lung disease, which has three distinct imaging patterns: diffuse centrilobular micronodules, high-attenuation perihilar and upper lobe predominant fibrotic opacities, and lower-lobe-predominant panlobular emphysema (Ritalin lung). It is often accompanied by right ventricular strain and pulmonary hypertension and can lead to sudden death and long-term deterioration of lung function. Additional complications of drug abuse include aspiration, lobar or bronchopneumonia, septic pulmonary emboli, and barotrauma. Recognition of SARLI patterns within the appropriate clinical and temporal context can help radiologists suggest the correct diagnosis and facilitate timely management.