Low-dose computed tomography volumetry for subtyping chronic lung allograft dysfunction.
BACKGROUND
The long-term success of lung transplantation is challenged by the development of chronic lung allograft dysfunction (CLAD) and its distinct subtypes of bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS). However, the current diagnostic criteria for CLAD subtypes rely on total lung capacity (TLC), which is not always measured during routine post-transplant assessment. Our aim was to investigate the utility of low-dose 3-dimensional computed tomography (CT) lung volumetry for differentiating RAS from BOS.


METHODS
This study was a retrospective evaluation of 63 patients who had developed CLAD after bilateral lung or heart‒lung transplantation between 2006 and 2011, including 44 BOS and 19 RAS cases. Median post-transplant follow-up was 65 months in BOS and 27 months in RAS. The median interval between baseline and the disease-onset time-point for CT volumetry was 11 months in both BOS and RAS. Chronologic changes and diagnostic accuracy of CT lung volume (measured as percent of baseline) were investigated.


RESULTS
RAS showed a significant decrease in CT lung volume at disease onset compared with baseline (mean 3,916 ml vs 3,055 ml when excluding opacities, p < 0.0001), whereas BOS showed no significant post-transplant change (mean 4,318 ml vs 4,396 ml, p = 0.214). The area under the receiver operating characteristic curve of CT lung volume for differentiating RAS from BOS was 0.959 (95% confidence interval 0.912 to 1.01, p < 0.0001) and the calculated accuracy was 0.938 at a threshold of 85%.


CONCLUSIONS
In bilateral lung or heart‒lung transplant patients with CLAD, low-dose CT volumetry is a useful tool to differentiate patients who develop RAS from those who develop BOS.
Latner Thoracic Surgery Research Laboratories, Toronto General Research Institute and Division of Thoracic Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada; Department of Thoracic and Cardiovascular Surgery, Kansai Medical University, Hirakara, Japan.
Tomohito
T
Saito
Cardiothoracic Division, Department of Medical Imaging, Time Resolved Imaging and Image Optimization Core Laboratory, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Miho
M
Horie
Latner Thoracic Surgery Research Laboratories, Toronto General Research Institute and Division of Thoracic Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada; Department of Thoracic Surgery, Kyoto University, Kyoto, Japan.
Masaaki
M
Sato
Latner Thoracic Surgery Research Laboratories, Toronto General Research Institute and Division of Thoracic Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada; Department of Thoracic Surgery, Kyoto University, Kyoto, Japan.
Daisuke
D
Nakajima
Cardiothoracic Division, Department of Medical Imaging, Time Resolved Imaging and Image Optimization Core Laboratory, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Hassan
H
Shoushtarizadeh
Division of Respirology, Department of Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Matthew
M
Binnie
Latner Thoracic Surgery Research Laboratories, Toronto General Research Institute and Division of Thoracic Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Sassan
S
Azad
Latner Thoracic Surgery Research Laboratories, Toronto General Research Institute and Division of Thoracic Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada.
David M
DM
Hwang
Latner Thoracic Surgery Research Laboratories, Toronto General Research Institute and Division of Thoracic Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Tiago N
TN
Machuca
Latner Thoracic Surgery Research Laboratories, Toronto General Research Institute and Division of Thoracic Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Thomas K
TK
Waddell
Division of Respirology, Department of Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Lianne G
LG
Singer
Latner Thoracic Surgery Research Laboratories, Toronto General Research Institute and Division of Thoracic Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Marcelo
M
Cypel
Latner Thoracic Surgery Research Laboratories, Toronto General Research Institute and Division of Thoracic Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada; Division of Respirology, Department of Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Mingyao
M
Liu
Cardiothoracic Division, Department of Medical Imaging, Time Resolved Imaging and Image Optimization Core Laboratory, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Narinder S
NS
Paul
Latner Thoracic Surgery Research Laboratories, Toronto General Research Institute and Division of Thoracic Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada; Department of Thoracic and Cardiovascular Surgery, Kansai Medical University, Hirakara, Japan. Electronic address: shaf.keshavjee@uhn.ca.
Shaf
S
Keshavjee
D000328:Adult; D064591:Allografts; D001989:Bronchiolitis Obliterans / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006084:Graft Rejection; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D016040:Lung Transplantation / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D055031:Primary Graft Dysfunction / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012372:ROC Curve; D011829:Radiation Dosage; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D014109:Total Lung Capacity / Q000502:physiology*
bronchiolitis obliterans syndrome; chronic lung allograft dysfunction; computed tomography volumetry; restrictive allograft syndrome; total lung capacity