Phenotyping emphysema and airways disease: Clinical value of quantitative radiological techniques

Table 1 Summary of studies dividing patients as HRCT defined phenotypes and their significant differences clinical and physiological (P < 0.05)

Ref.	HRCT defined phenotypes	Variables studied	Significant variable difference
Kitaguchi et al[8], 2006	A: Little or none of either emphysema or BWT E: Emphysema but no BWT M: Emphysema and BWT	Gas exchange Gas transfer Lung function Response to beta-agonist Response to treatment with ICS Sputum cell differentiation	A: ↑ BMI ↑DLCO ↓ hyperinflation ↑ reversibility ↑response to ICS ↑ % of sputum eosinophils E: No response to ICS M: ↑ response to ICS ↑ % of sputum eosinophils
Fujimoto et al[9], 2006	A: Little or none of either emphysema or BWT E: Emphysema but no BWT M: Emphysema and BWT	Exacerbation rates Gas exchange Gas transfer Hospital admissions Lung function Response to beta-agonist Symptoms	M: ↑ volume of sputum, exacerbation rate and admission to hospital
Pistolesi et al[10], 2008	From derivation set, created new validation set Group A and B	CT parameters Gas exchange Gas transfer Lung function	A: ↓ FEV1, ↑ TLC ↓ DLCO. ↑ pixel index (threshold -950HU) B: ↑ BMI purulent sputum worse bronchial wall thickening
Han et al[7], 2011	Emphysema predominant or Airway predominant	BWT Exacerbation rates lung function % emphysema	Emphysema Predominant (> 35% -950HU): ↓ FEV1 and 6MWD ↑ SGRQ and MRC grade For every 5% ↑ in emphysema, 1.18 fold ↑ exacerbation frequency Airways predominant: For 1 mm ↑ in segmental BWT 1.84 fold ↑ in exacerbation frequency
Subramanian et al[3], 2016	Emphysema dominant, airways disease dominant, mixed pathology and mild disease	Blood parameters CT parameters Gas exchange Gas transfer Lung volumes Spirometry	Compared with airway disease dominant group, emphysema dominant group had ↑ lung volumes, ↓ gas transfer ↓ pO2 + pCO2↓BMI ↑Hb No difference between age, and smoking history between the groups
Da Silva et al[2], 2016	Emphysema or airways disease	Clinical + functional evaluation HRCT	Emphysema group: ↑ airflow obstruction ↓ BMI ↓ 6MWD

A: Airways; E: Emphysema; M: Mixed; BWT: Bronchial wall thickening; 6MWD: 6 minute walk distance; CT: Computed tomography; BWT: Bronchial wall thickness; DLCO: Transfer factor for carbon monoxide; ICS: Inhaled corticosteroid; FEV1: Forced Expiratory Volume in 1 second; TLC: Total lung capacity; HU: Hounsfield units; SGRQ: St Georges Respiratory Questionnaire; MRC: Medical reseach council; HRCT: High resolution computed tomography.