Pulmonary Abnormalities on High-Resolution CT Demonstrate More Rapid Decline Than FEV1 in Adults With Cystic Fibrosis: Recommendation

Our findings would support the concept that while longitudinal structural abnormalities are clearly seen with HRCT, their longitudinal functional significance is less clear-cut. Other imaging techniques such as hyperpolarized He MRI may prove a useful alternative in obtaining longitudinal functional information. We recently evaluated He MRI in CF adults and found it to be a strong correlate of structural HRCT abnormalities and a stronger correlate of spirometry than HRCT. We envisage, although currently hypothetical, that spirometry, He MRI, and HRCT may work synergistically to provide longitudinal functional and structural information in CF. add comment
Our study has several limitations. It is retrospective, and spirometry was not performed on the same day as HRCT in some patients. However, we sought to be meticulous in excluding patients with clinical symptoms/signs of a respiratory exacerbation in the immediate period prior to HRCT. We included all consecutive patients with HRCT scans > 18 months apart, rather than just patients with stable spirometry results over a significant time period. We believe this reflects the more typical clinical spectrum of adults with CF. Since all patients in our center electively undergo HRCT, we hoped this would minimize potential patient selection bias. Nevertheless, it is possible that healthier patients with HRCT scans at clinically stable periods were selected over patients with more severe disease. However, our group had a wide spectrum of lung function impairment, and we believe selection bias to be minimal. Not all patients underwent comprehensive spirometric evaluation, although FEV1 and FVC, which are the major spirometric measures used in CF, were available in all patients.
Radiation dose to patients remains an inherent limitation of HRCT. Recent estimates of lifelong HRCT surveillance in patients with CF show a low risk for cancer-induced mortality. Technological advances such as automatic tube modulation and use of low-dose HRCT protocols may further reduce radiation exposure. Such findings have implications for routine HRCT surveillance and use as an outcome measure in CF. Our results would support such an application in adults, but further work demonstrating that independent changes in HRCT consistently correlate with changes in clinical outcome measures across several studies is required to substantiate this proposal.
In conclusion, in CF adults with stable FEVj several HRCT abnormalities deteriorate significantly. Even in adults with declining FEV1, HRCT abnormalities show more rapid deterioration. Different HRCT abnormalities worsen at different rates in groups with mild and moderate-to-severe lung function impairment.

This entry was posted in Cystic Fibrosis and tagged , , , .