David M. Hansell, MD, FRCR, FRCP, FRSM ESTI SPEAKER SUNDAY Pitfalls in the HRCT Diagnosis of Fibrosing Lung Disease Why segregate fibrosing lung disease from other DLDs? Pitfalls in the HRCT diagnosis of fibrosing lung disease What are the HRCT signs of fibrosing DLD? reliability of signs Diagnostic HRCT algorithm for fibrosing DLD Problems in fibrosing DLD David M Hansell Royal Brompton Hospital London UK HRCT off non-classical l l UIP HRCT pitfalls in acute exacerbation of IPF Why consider fibrotic ILD and non-fibrotic ILD separately? Expectation of certain disease behavior Idiopathic pulmonary fibrosis in particular Prospect of enrolment into drug trial Differential diagnosis g much shorter (bonus!) BASICS HRCT signs of a predominantly fibrotic lung disease: Honeycombing Traction bronchiectasis Volume loss Reliability of HRCT signs of fibrotic lung disease (++++ = complete certainty) Honeycombing Honeycomb pattern +++(+) Traction bronchiectasis ++(+) Volume loss + Traction bronchiectasis Volume loss 85 SUNDAY Honeycomb pattern Traction bronchiectasis Volume loss Honeycombing Identification of honeycombing on HRCT - cardinal sign of UIP False positive identification Centrilobular/paraseptal emphysema e.g. superimposed on NSIP Severe traction bronchiolectasis Other cystic conditions e.g. Langerhans CH (False negative) Microcystic y or microscopic p honeycombing y g (path) (p ) 86 SUNDAY Lung biopsy: Fibrotic NSIP and centrilobular emphysema Interobserver variability in the CT assessment of honeycombing in the lungs Historically poor: Lynch et al (2005) =0.31 43 observers b (!) Honeycombing present definitely yes (5) thro d fi it l nott (1) definitely Agreement with reference standard moderate 0 43 0 58 =0.43-0.58 In 29% disagreement on presence/absence Sources S off di disagreement: t ttraction ti bx, b cysts t and d superimposed emphysema Watadani et al Radiology 2013;266:207 Identification of traction bronchiectasis on HRCT False positive identification Traction bronchiectasis Within honeycombing Dilated bronchi within OP Airwayy dilatation in acute lungg injury j y Conspicuous, but not dilated, bronchi within GGO False negative Within honeycombing (usually advanced) 87 SUNDAY After withdrawal of nitrofurantoin Sheehan et al J Thorac Imag 2000;24:259 Observer agreement for traction bronchiectasis in various FLD Fibrotic IIPs (UIP and NSIP) Edey 2011 Eur Radiol Rheumatoid Arthritis-related FLD Kim Ki 2010 Eur E Respir R i J Chronic hypersensitivity pneumonitis Walsh SL 2012 Eur Radiol All comers connective tissue disease FLD Walsh SL unpublished p data Kappas for traction bronchiectasis = 0.58 - 0.69 Study by Sakai et al - in progress 88 Interlobular septal p thickeningg in fibrosing lung disease A common feature in UIP not really! Rarely R l conspicuous i iin NSIP If prominent, nodular and lower zone consider sarcoidosis as the cause of the FLD May be an early sign of supervening fibrosis in subacute hypersensitivity pneumonitis SUNDAY Two examples of NSIP Two examples of sarcoidosis Coche et al. al Br J Radiol 2001;74:189 Two examples of chronic hypersensitivity h iti it pneumonitis iti HRCT pointers to chronic hypersensitivity pneumonitis Lobules of decreased attenuation in spared (nonfibrotic) lung Septal thickening tends to be more prominent than in fibrotic IIPs Unusual distribution of fibrosis, particularly vague bronchocentricity in upper lobes Coexistent subacute changes - indistinct relatively low attenuation centrilobular nodules (rare) 89 SUNDAY Lobules of decreased attenuation in spared p lungg Chronic hypersensitivity with UIP features Unusual distribution of fibrosis,, particularly p y vague bronchocentricity in upper lobes Scheme for HRCT of fibrosing lung disease: Is it a fibrosingg lungg disease (3 ( signs)? g ) If yes, is it classical UIP? If no, what are the choices? Characteristic/Classical HRCT pattern of UIP Subpleural Basal Honeycombing ALSO Propeller Propeller blade blade cranio-caudal cranio caudal distribution Absence of atypical features, features in particular: Subpleural basal honeycombing UIP 90 Lobules of decreased attenuation in spared lung Consolidation SUNDAY If not typical UIP: Non-classical N l i l UIP Older increasing likelihood of UIP Fell CD et al. AJRCCM 2010;181:832 Non-specific p interstitial p pneumonia ((NSIP)) Chronic hypersensitivity pneumonitis Fibrotic sarcoidosis ((Fibrosingg variant of organizing g g pneumonia) p ) OP OP UIP UIP NSIP HP NSIP LIP HP DIP/ RB-ILD Other HRCT diagnoses in patients with biopsy proven UIP 3 observers assigned diagnoses to HRCTs of 123 cases (core of 55 patients with biopsy proven UIP) 34/55 (62%) considered not to be typical of UIP: NSIP 18/34 (53%); HP (12%); sarcoidosis (9%) A diagnosis of IPF is not excluded by HRCT appearances more suggestive tiv off NSIP Sverzellati et al Radiology 2010;254:957 LIP DIP/ RB-ILD UIP pattern (all four features) Possible UIP pattern (all three features) Subpleural basal predominance Subpleural basal predominance Reticular abnormality Reticular abnormality Inconsistent with UIP pattern (any one of seven features) Upper or mid lung predominance Peribronchovascular predominance Extensive ground glass abnormality (extent > reticular abnormality) Profuse micronodules (bilateral predominantly upper (bilateral, lobes) Honeycombing with or without traction bronchiectasis Discrete cysts (multiple bilateral, away from areas of honeycombing) Diffuse mosaic attenuation/air trapping (bilateral in three or more lobes) Absence of features listed as inconsistent with UIP pattern Absence of features listed as inconsistent with UIP pattern Consolidation in bronchopulmonary segment(s)/lobe(s) Possible Possible no HC, no inconsistent features ATS/ERS/JRS/ALAT statement: Idiopathic pulmonary fibrosis. Am J Respir Crit Care Med 2011;183:788 91 SUNDAY Range of HRCT appearances of non classical UIP non-classical Does a definite diagnosis of IPF/UIP matter? YES! For the patient/doctor: prognosis For exclusion of cryptic yp driver of the disease For possible entry into drug trial not fully explored Acute exacerbation (accelerated phase) of IPF Iff it behaves like UIP it is UIP ATS/ERS statement - IIP update 2013: C Consensus on di diagnosis i and d managementt HR Collard et al. AJRCCM 2007;176: 636 Acute Exacerbation 5 weeks eek later lat 92 Differential diagnosis for recent onset of widespread ground glass opacification in IPF/UIP: Accelerated phase of the disease S Supervening i h heartt ffailure il ((oedema) d ) Opportunistic infection (PCP/CMV) Drug reaction esp. novel drugs ((Spurious p expiratory p y CT)) (Spurious contrast in CTPA) SUNDAY Pulmonary oedema P Pneumocystis ti pneumonia i Expiratory CT Points Three Th basic b i signs i off fib fibrosing i llung di disease Issues with certain identification of honeycombing and traction bronchiectasis Main HRCT differential of fibrosing lung disease is UIP -v- chronic HP/NSIP CTPA (contrast) C Considerations id ti when h HRCT appearances are suggestive of acute exacerbation 93
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