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April 2, 2021 — A Scientific E-Poster to be presented at the 2021 ARRS Virtual Annual Meeting reveals increased rates of emphysema in marijuana smokers, compared to both non-smokers and tobacco-only smokers, as well as greater rates of paraseptal emphysema.
"Marijuana smoking is also associated with airways disease, including bronchial wall thickening, bronchiectasis, and bronchiolar mucoid impaction, in comparison to both the control group and tobacco-only group," wrote first author Luke Murtha of Ottawa Hospital in Canada.
Querying imaging reports on Ottawa Hospital's PACS, Murtha and colleagues identified three groups of patients, matched for age and sex: marijuana smokers (n=56); a control group of non-smokers/non-marijuana users (n=57); and a comparison subgroup consisting of tobacco-only smokers (n=33). Two board-certified, fellowship-trained radiologists--blinded to clinical data such as smoking and marijuana history--performed consensus reading of the chest CTs.
In main-group marijuana smoking patients (75%), rates of emphysema were greatly elevated, compared to main-group control patients (5%). Age-matched subgroup analysis demonstrated a significant increase in emphysema in marijuana (93%) patients, compared to tobacco-only smokers (66%), as well as a significant increase in the proportion of paraseptal emphysema (versus other types) in marijuana smokers (53%), when compared to both tobacco-only smokers (24%) and control groups (7%).
Noting the lack of data concerning the physical effects of marijuana on the lungs, "given that marijuana use is increasing, particularly within nations such as Canada, that have legalized the substance, it is important for us, as radiologists, to define specific findings associated with its consumption," the authors of this ARRS Annual Meeting E-Poster concluded.
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June 12, 2026 
