High-resolution CT of idiopathic interstitial pneumonias

Important recent changes have occurred in our understanding of the IIPs. IPF (characterized histologically as UIP) is recognized as a progressive disease with a relatively poor prognosis, and with a characteristic CT appearance. The radiologist must be able to distinguish between UIP and the other IIPs. Complications of IPF include accelerated progression, lung cancer, and secondary infection. NSIP has a better prognosis than IPF, and has ground-glass attenuation as its salient CT feature. COP (formerly known as BOOP) is included as an IIP because its clinical, physiologic, and imaging features overlap with those of the other IIPs. It is characterized on CT by consolidation and ground-glass attenuation. AIP is the idiopathic form of ARDS. LIP and DIP are less common IIPs, both characterized by ground-glass attenuation.