E1756. CT Chest Findings in Marijuana Smokers
  1. Luke Murtha; The Ottawa Hospital
  2. Paul Sathiados; The Ottawa Hospital
  3. Matthew Mcinnes; The Ottawa Hospital
  4. Giselle Revah; The Ottawa Hospital
Little data exists in the literature concerning the physical effects of marijuana on the lungs. The majority are case reports or case series, which focus on marijuana’s relationship to PFTs, symptoms, and association with lung cancer. Few studies have focused on the imaging findings associated with marijuana smoking. 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.

Materials and Methods:
Three groups of age and sex matched patients were identified through a search of imaging reports on The Ottawa Hospital PACS: 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. CTs were evaluated for: emphysema, bronchial thickening, bronchiectasis, mucoid impaction, patterns of nodularity, fibrosis and CAD.

Rates of emphysema in main-group marijuana smoking patients (75%) were greatly elevated in comparison to main-group control patients (5%) [X2 (1,113) = 57.32, p <.001]. Age-matched subgroup analysis demonstrated a significant increase in emphysema in marijuana (93%) patients compared to tobacco-only smokers (66%) [X2(1,63)=6.82, p =.008997], 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%) [X2(1,63)=5.64, p =.017564] and control groups (7%) [X2(1,59)=15.00, p =.000108]. Bronchial thickening in marijuana smokers was increased in comparison to both controls (64% vs 11%) [X2(1,113)=34.96, p <.001], and age-matched tobacco only smokers (83% vs 42%) [X2(1,63)=11.15, p <.00084]. Bronchiectasis rates in marijuana smokers were increased in comparison to both controls (23% vs 4%), [X2(1,113)=9.53, p =.002024], and age-matched tobacco only smokers (33% vs 6%) [X2(1,63)=7.58, p =.005901]. Mucoid impaction rates in marijuana smokers were increased in comparison to both controls (87% vs 2%) [X2(1,113)=31.00, p <.001] and age-matched tobacco only smokers (67% vs 15%) [X2(1,63)=17.42, p <.001]. There was no significant difference in rates of CAD in the age matched marijuana smoking group (70%), in comparison to either controls (48%) [X2(1,59)=2.88, p =.08947] or tobacco-only smokers (84%) [X2(1,63)=2.0045, p =.156828].

Our study reveals increased rates of emphysema in marijuana smokers in comparison to both non-smokers and tobacco-only smokers, as well as a tendency to 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.