Radiological diagnosis of fibrosing interstitial lung diseases: innovations and controversies

Following the introduction of new effective antifibrotic drugs, interest in fibrosing interstitial lung diseases (FILD) has been renewed. In this context, radiological evaluation of FILD plays a cardinal role. Radiological diagnosis is possible in about 50% of the cases, which allows the initiation of effective therapy, thereby avoiding invasive procedures such as surgical lung biopsy. Usual interstitial pneumonia (UIP) pattern may be diagnosed based on clinical, radiological, and pathological data. High-resolution computed tomography features of UIP have been widely described in literature; however, interpreting them remains challenging, even with specific expertise on the subject. Diagnostic difficulties are understandable given the continuous evolution of FILD classifications and their complexity. Both early-stage diseases and advanced or combined patterns are not easily classifiable, and many end up being labelled 'indeterminate´ or 'unclassifiable´. Especially in these cases, optimal patient management involves collaboration and communication between different specialists. Here, we discuss the most critical aspects of radiological interpretation in FILD diagnosis based on the most recent classifications. We believe that the clinicians´ awareness of radiological diagnostic issues of FILD would improve comprehension and dialogue between physicians and radiologists, leading to better clinical practice.