The second edition of PCD paper summaries is here, and this week we look at CT scans in PCD vs. CF!
Bronchiectasis in PCD looks different to CF on CT scan
Summary of Robinson P, Morgan L. Bronchiectasis in PCD looks different to CF on CT scan. Multidiscip Respir Med. 2018;13(Suppl 1):24. Published 2018 Aug 9. doi:10.1186/s40248-018-0139-2
Computerized Tomography (CT) scan is an important imaging tool to detect bronchiectasis and, by using one of several scoring systems, monitor severity of disease over time. These scoring systems, which include: the Bhalla Score, the Brody score, and the Helbich score, have been specifically developed for use in patients with cystic fibrosis (CF), and it is not clear whether these systems are sufficient or appropriate for other forms of non-CF bronchiectasis, including primary ciliary dyskinesia (PCD). It is noted that CT scoring systems are used for clinical research and care, but with a system skewed toward CF, it is unclear how valuable it is for non-CF bronchiectasis. An example of the CT scoring system favoring CF would be the newborn screening CT, which enables detection of CF at birth and allows for the patient to begin targeted treatment and therapy immediately. This is not the case with PCD, however, as people are often diagnosed at a later time, sometimes even into adulthood. While PCD and CF do have many similarities in symptoms and in treatment therapies, the underlying causes of bronchiectasis are different in the two diseases. Thus, the authors of this paper, Robinson and Morgan, questioned if a CT scoring system specifically designed for PCD would be necessary in order to properly identify and track PCD unique structural changes and to mitigate the risk of something being overlooked or missed on a scan.
The authors recently reviewed CT scans conducted on 19 children and adolescents with PCD. All had a confirmed PCD diagnosis, based on current guidelines, including classic phenotypes (symptoms), as well as diagnostic tools such as genetics, nasal NO, electron microscopy, and high speed-video-microscopy. A qualified respiratory physician analyzed the scans by ranking radiological abnormalities by range and frequency, as opposed to using the CF scoring model. The physician found that only 3 of the 38 (8%) upper lobes showed signs of bronchiectasis, compared to 35 of 38 (92%) of the lower lobes. In the middle lobes, bronchiectasis was present at a rate of 79%, and atelectasis (collapsed lobe) was seen at a rate of 75%. The results show that the upper lobes are mostly spared from severe bronchiectasis in PCD, which is a stark contrast to that of CF where upper lobe bronchiectasis is dominant. It is reasonable to assume that the PCD unique bronchiectasis structural features would be improperly weighted using the CF scoring systems.
The preliminary data from Robinson and Morgan indicates that “structural lung disease in PCD has unique features both in lobar localization and structural nature.” Furthermore, the CF scoring system does not take these unique features into account and could provide an incomplete picture of what exactly is going on in the lungs of PCD patients. In order to properly identify the severity of bronchiectasis in PCD and to track changes over time, it was concluded that a PCD specific CT scoring system should be developed using the same type of international, multi-center, large PCD patient group approach that was successfully used to develop the CF CT scoring systems for the CF community. A PCD CT scoring system could help improve early diagnosis and developing a treatment protocol to slow the progression of bronchiectasis in PCD patients. If you would like to dive a little deeper into CT scans, here is the link to article.
Billy Anton
PCD Foundation Board of Directors Vice-Chair