Review of quantitative and functional lung imaging evidence of vaping-related lung injury

Abstract

Introduction: The pulmonary effects of e-cigarette use (or vaping) became a healthcare concern in 2019, following the rapid increase of e-cigarette-related or vaping-associated lung injury (EVALI) in young people, which resulted in the critical care admission of thousands of teenagers and young adults. Pulmonary functional imaging is well-positioned to provide information about the acute and chronic effects of vaping. We generated a systematic review to retrieve relevant imaging studies that describe the acute and chronic imaging findings that underly vaping-related lung structure-function abnormalities.

Methods: A systematic review was undertaken on June 13th, 2023 using PubMed to search for published manuscripts using the following criteria: [("Vaping" OR "e-cigarette" OR "EVALI") AND ("MRI" OR "CT" OR "Imaging")]. We included only studies involving human participants, vaping/e-cigarette use, and MRI, CT and/or PET.

Results: The search identified 445 manuscripts, of which 110 (668 unique participants) specifically mentioned MRI, PET or CT imaging in cases or retrospective case series of patients who vaped. This included 105 manuscripts specific to CT (626 participants), three manuscripts which mainly used MRI (23 participants), and two manuscripts which described PET findings (20 participants). Most studies were conducted in North America (n = 90), with the remaining studies conducted in Europe (n = 15), Asia (n = 4) and South America (n = 1). The vast majority of publications described case studies (n = 93) and a few described larger retrospective or prospective studies (n = 17). In e-cigarette users and patients with EVALI, key CT findings included ground-glass opacities, consolidations and subpleural sparing, MRI revealed abnormal ventilation, perfusion and ventilation/perfusion matching, while PET showed evidence of pulmonary inflammation.

Discussion and conclusion: Pulmonary structural and functional imaging abnormalities were common in patients with EVALI and in e-cigarette users with or without respiratory symptoms, which suggests that functional MRI may be helpful in the investigation of the pulmonary health effects associated with e-cigarette use.

Keywords: CT; EVALI; MRI; PET; e-cigarettes.

Figure 1

Typical commercial electronic cigarette or vape device.

Figure 2

Distribution of vape flavors by preference. Figure was created using data from Canadian Tobacco and Nicotine Survey (CTNS) (14).

Figure 3

Schematic of airway tree conducting and respiratory zone. The human airway tree consists of the conducting zone and respiratory zone, with corresponding generation, number and diameter shown. Adapted from Nunn’s Applied Respiratory Physiology, 8th edition.

Figure 4

Potential mechanisms of pulmonary injury associated with vaping.

Figure 5

Flow chart of study search and selection process.

Figure 6

CT imaging of e-cigarette-related or vaping-associated lung injury (EVALI) with short-term follow-up. P01: axial CT of a 35 years-old female with diffuse alveolar damage pattern who vaped THC. (A) CT imaging showed ground-glass opacities with areas of consolidation, subpleural and perilobular sparing (arrows) and septal thickening (arrowhead). (B) CT 2 weeks later showed extensive right lung consolidation with areas of bronchial dilation (arrow) and internal development of right pneumothorax. Patient died 5 days later. P02: axial CT of a 51 years-old female showing multiple episodes of EVALI following repeated vaping of nicotine with mint flavoring. (A) CT imaging showed scattered areas of ground-glass opacities with subpleural sparing. (B) Two months later, the patient returned to emergency department with dyspnea and fever. CT findings included more extensive ground-glass opacities with areas of lobular and subpleural sparing. Septal thickening is present creating “crazy paving” pattern. Patient’s condition deteriorated, and was complicated by aspiration pneumonia and bilateral lower-lobe collapse. P03: axial CT of organizing pneumonia pattern in a 20 years-old male who vapes nicotine and THC products daily. (A) CT imaging showed peribronchiolar ground-glass opacities with subpleural sparing (black arrows). Areas of bronchial dilation are seen in areas of ground-glass opacities (white arrow). (B) Four weeks following steroid therapy, the patient’s CT scan was normal. Images reproduced with permission from Kligerman et al. (40).

Figure 7

PET imaging tracking metabolic activity in e-cigarette users and smokers. (A) Oronal PET/CT ¹⁸F-NOS in an e-cigarette user (unspecified active ingredient). Uptake is shown 0–15 s and 37–42 s after injection of ¹⁸F-NOS to quantify oxidative stress and inflammation in the lungs. Adapted from Wetherill et al. (109) under Creative Commons License. (B) Representative distribution of ¹¹C-nicotine freebase and lactate in lungs at 0.5 and 5 min after inhalation of the tagged nicotine salts through an e-cigarette in a healthy adult smoker. Adapted from Wall et al. (92) under Creative Commons License.

Figure 8

Hyperpolarized ¹²⁹Xe MR ventilation imaging in chronic vapers and similar-aged healthy volunteer. Anterior, central, and posterior coronal slices of ¹²⁹Xe ventilation (cyan) co-registered with anatomical ¹H (greyscale) MRI. All images were acquired by the authors’ group. P01 is an 18 years-old male with severe bronchiolitis and respiratory failure caused by e-cigarette use, 1 month post discharge after a 6 months history of vaping (VDP = 21%). P02 is a 29 years-old male with a 2.5 years history of vaping nicotine (3/4 pods daily) (VDP = 4.7%). P03 is a 22 years-old male with no history of chronic respiratory abnormalities, vaping or combustible cigarette use (VDP = 1.5%).

Figure 9

Free-breathing ¹H MRI of acute effects of vaping. (A) Pulmonary perfusion images obtained by using non-contrast matrix pencil MRI in three electronic nicotine vape users before and after exposure. The arrows indicate lung regions with increased regional perfusion post-exposure. Red corresponds to greater perfusion amplitude and blue corresponds to lower values (108). (B) Spatial maps of ventilation, perfusion, and ventilation-perfusion ratios, before and after vaping, in a single sagittal slice of one representative subject. Black regions within the lung field represent regions excluded from analysis, including conducting airways and vessels, and regions with poor signal to noise (107).