Airway imaging practices in primary ciliary dyskinesia: a global survey to guide standardized guidelines

Abstract

Objectives

Airway imaging guidelines for primary ciliary dyskinesia (PCD) are currently limited. Given the progressive nature of this disease, standardized imaging protocols, particularly at key clinical milestones such as diagnosis, routine reviews, and exacerbations, may improve monitoring of disease progression, support comparison of outcomes across centers, and provide robust parameters for clinical trials.

Methods

To document current practices, we conducted a global survey of PCD clinicians. An online questionnaire was distributed via international PCD networks, covering imaging use at diagnosis, during routine assessments, and at exacerbations treated with oral or intravenous antibiotics. Responses were received from 120 clinicians across 90 centers in 33 countries. Modalities assessed included X-ray, CT scans, MRI, and ultrasound, with analyses stratified by center type and size.

Results

At diagnosis, 94% of clinicians reported using imaging. Chest X-ray was most common for children under 5 years (55%), whereas CT was preferred for older patients (66%). During routine assessments, 67.5% of clinicians used imaging, but timing and modality varied, with CT more frequent in pediatric and mixed centers. Imaging during exacerbations differed by treatment route: chest X-ray was the most common modality, used by 57.1% for oral antibiotic-treated episodes and 73.3% for intravenous episodes. CT use was higher with intravenous treatment (15.8% vs. 4.2%).

Conclusions

Although practices varied, consistent trends at diagnosis and follow-up highlight opportunities for consensus.

Advances in knowledge

Standardized imaging protocols could enhance clinical care, enable meaningful research comparisons, and improve outcomes in PCD.

Introduction

Primary ciliary dyskinesia (PCD) is an inherited, progressive disorder characterized by chronic suppurative disease of the upper and lower airways. Effective patient monitoring includes microbiological analysis of airway secretions, lung function testing, and imaging. Given its progressive nature, structured guidelines for disease assessment are critical to track progression and guide therapy.

In contrast to cystic fibrosis (CF), where guidelines recommend biennial chest X-rays and CT scans every 2-3 years,^1,2 current PCD guidelines lack specific recommendations regarding imaging modality and frequency. The 2016 USA PCD Foundation consensus suggests chest X-rays every 2-4 years, while CT scans “could be considered at least once after age 5-7 years.” This contrasts with CF Foundation pediatric guidelines, which recommend chest X-rays at least every other year, and CT scans “considered every 2-3 years.”² Similarly, the European CF Society recommends annual chest radiographs for all patients.³ While recognizing that the progression of CF lung disease may have a different trajectory from that of PCD, this discrepancy and absence of standardized imaging protocols in PCD limits comparisons of structural lung disease between centers, and hampers evaluation of treatment effects in multicenter studies.^4,5

To address this gap, and as a first step toward establishing guidelines for monitoring structural lung disease in PCD, we conducted a global survey of 120 PCD clinicians to document current airway imaging practices, at diagnosis, during routine assessments (eg, annual reviews), and during exacerbations treated with either oral, or intravenous, antibiotics. By capturing these diverse clinical approaches, this report aims to describe current practices and support the development of evidence-based imaging guidelines for PCD, enhancing both clinical care and research.

Methods

A questionnaire concerning the use of medical imaging during the follow-up of people with PCD (pwPCD) was developed by an experienced PCD clinician. It was distributed to clinicians responsible for imaging decisions, and those managing more than 10 PCD patients, via several international PCD networks, including the BEAT-PCD Consortium, ERN-Lung PCD group, and the North American PCD Foundation.

The questionnaire, hosted on the REDCap platform⁶, comprised 4 sections:

• Demographics: Responders provided their center’s location (country and city), patient population (pediatric, adult, or combined), and the number of PCD patients regularly seen (<50, 50-100, >100).

• Imaging at diagnosis: Clinicians were asked whether imaging was used at diagnosis and asked to specify the modalities applied in 3 age groups (0-5, 6-11, and ≥12 years).

• Imaging in stable assessments: Questions addressed imaging during routine assessments (eg, annual reviews), including imaging modality, frequency (annually, biennially, every >2 years, or as clinically needed), and use of general anesthesia for CT or MRI.

• Imaging During Exacerbations: Clinicians reported imaging practices during exacerbations, defined as changes from baseline respiratory symptoms requiring oral or intravenous antibiotics, including frequency of use (never, not in the majority of cases [rarely], occasionally, always) and modality (chest X-ray, CT, MRI, ultrasound, or other).

Responses were collected anonymously. As the aim of this scoping questionnaire study was to explore current practice patterns rather than test hypotheses, data were primarily analyzed descriptively. However, the chi-square test was used to assess differences in imaging practices by patient age group and imaging modality. No further between-group statistical comparisons were performed.

The study was approved by the institution’s local Human Ethics Committee (Reference: 4254).

Results

Responses were received from 120 clinicians across 90 PCD centers in 33 countries (Figure 1), with only one incomplete questionnaire. Centers were categorized by size and type (Table 1): 54 clinicians worked at centers following fewer than 50 patients (small), 30 at centers treating 50-100 patients (medium), and 36 clinicians worked at centers treating more than 100 patients (large). By patient population, 46 clinicians focused on pediatric patients only, 13 clinicians on adults only, and 61 clinicians treated a combined pediatric and adult age group.

Figure 1.

Participating countries (red).

Table 1.

Clinicians according to center size and type.

Center size/type	Pediatric only	Adult only	Combined pediatric + adult	Total
<50 (small)	27	8	19	54
50–100 (medium)	11	3	16	30
>100 (large)	8	2	26	36
Total	46	13	61	120

Imaging at diagnosis

At PCD diagnosis, 94% of clinicians (113/120) reported using imaging. For children under 5 years, chest X-rays were preferred (55%), with CT scans used by 33%. In older children (6-11 years) and adolescents/adults (≥12 years), chest CT was the dominant modality (66% in both groups), while chest X-rays were used by 24% and 22%, respectively. Seven clinicians (6%) from a mix of pediatric and combined-age centers of varying sizes, did not use imaging. Imaging modality differed significantly by age group (P < .01), with chest X-rays more frequently chosen for children under 5 years compared with both older groups, whereas preferences between the 6-11 and ≥ 12 age groups were similar (P = .81) (Figure 2).

Figure 2.

Imaging choices at PCD diagnosis across age groups. Bars show the number of clinicians who used Chest X-ray (blue), CT scans (orange), or other (grey). Responses are from 120 respondents and more than one modality could be selected by each respondent.

Imaging during routine assessments

During annual reviews, typically performed while patients are in stable condition, 67.5% of clinicians (81/120) reported using imaging, with chest X-rays selected by 47/81 (58%) of clinicians, followed by CT, 53/81 (65.4%) and MRI in 11/81 (13.6%). CT scans were common in both pediatric-only (21/33, 63.6%), and mixed pediatric/adult centers (26/41, 63.4%), and were the predominant modality used in adult-only centers (6/7, 85.6%). Among large-center clinicians, 19/21 (90.5%) reported using chest X-ray, and 8/21 (38.1%) used CT scans. MRI was used by 13.5% (11/81) across 10 centers in 6 countries, primarily in small pediatric centers. Imaging frequency varied: 27% annually, 35% biennially, and 31% less frequently, reflecting diverse practices.

Imaging during exacerbations

Oral antibiotic-treated exacerbations

Among 119 clinicians who provided responses (1 missing), during exacerbations requiring oral antibiotics, imaging was used infrequently: 40/119 (33.6%) reported using it rarely, 1/119 (0.8%) never, 68/119 (57.1%) occasionally, and 10/119 (8.4%) always.

• By center type: imaging was less frequent in pediatric centers (21/46 rarely, 20/46 occasionally) and combined-age centers (17/61 rarely, 39/61 occasionally).

• By center size: small centers (23/54 rarely, 27/54 occasionally) and large centers (7/36 rarely, 24/36 occasionally) showed similar patterns.

• Modalities used: chest X-rays were selected by 68/119 clinicians (57.1%), with use across pediatric (23/46), adult (10/13), and combined-age (35/61) centers. CT scans were reported by 5/119 clinicians (4.2%), ultrasound by 3/119 (2.5%), and “other” imaging by 1/119 (0.8%). No responders reported MRI use.

Intravenous antibiotic-treated exacerbations

All 120 clinicians provided responses. During exacerbations requiring intravenous antibiotics, imaging was much more common: 8/120 (6.7%) reported using it rarely, 47/120 (39.2%) occasionally, and 65/120 (54.2%) always.

• By center type: use was highest in adult centers, where 10/13 clinicians (76.9%) reported always using imaging, compared with 19/46 (41.3%) in pediatric centers and 36/61 (59.0%) in combined-age centers. Occasional use was more frequent in pediatric centers (22/46, 47.8%) compared with combined-age (23/61, 37.7%) and adult (2/13, 15.4%) centers. Rare use was almost absent in adult centers (1/13, 7.7%) but still present in pediatric (5/46, 10.9%) and combined-age (2/61, 3.3%) centers.

• By center size: large centers reported the highest proportion of always use (23/36, 63.9%), compared with 27/54 (50.0%) in small and 15/30 (50.0%) in medium centers. Occasional use was most frequent in small centers (21/54, 38.9%), followed by medium (13/30, 43.3%) and large (13/36, 36.1%). Rare use was more common in small centers (6/54, 11.1%) compared with medium (2/30, 6.7%) and absent in large centers.

• Modalities used: chest X-rays were the most common (88/120, 73.3%), reported by pediatric (36/46), adult (10/13), and combined-age (41/61) clinicians. CT use increased compared with oral exacerbations (19/120, 15.8%), including 7/46 pediatric and 11/61 combined-age clinicians. Ultrasound was used by 2/120 clinicians (1.7%), MRI by 1/120 (0.8%), and “other” imaging by 1/120 (0.8%).

Imaging frequency according to center type, comparing oral with intravenous antibiotics, is shown in Figure 3.

Figure 3.

Imaging frequency during pulmonary exacerbations, comparing oral and intravenous antibiotic treatment across center types (pediatric, adult, combined). Bars show the proportion of clinicians who reported using imaging rarely (blue), occasionally (orange), or always (grey). A small proportion of pediatric clinicians reported “never” using imaging during oral antibiotic-treated exacerbations (not visible on the chart). Percentages are based on 119 valid responses for oral exacerbations (1 missing) and 120 responses for intravenous exacerbations.

Discussion

This global survey of 120 experienced PCD clinicians from 33 countries and 90 centers provides the most comprehensive overview to date of airway imaging practices in PCD. The findings establish a valuable foundation for the development of standardized imaging guidelines. While individual imaging decisions must ultimately be tailored to each patient’s clinical presentation, particularly during exacerbations, the consensus reflected in responses regarding imaging at diagnosis and during routine reviews offers important insights that can guide future recommendations.

At diagnosis, more than 90% of clinicians reported using imaging. In children under 5 years, chest X-ray was the preferred modality (55%), with CT scans used less frequently (33%). Among children aged 6-11 years, CT became the predominant choice (66%), with chest X-rays selected by only 24%. This shift likely reflects concerns about the need for general anesthesia in younger children. In patients over 12 years, CT remained the preferred modality (66%), while chest X-rays were chosen by 22%. The similar imaging patterns observed in the 6-11 and over-12 age groups suggest that consensus recommendations could align these groups. A practical guideline could therefore propose chest X-rays for children under 5 years and CT scans for older patients.

For annual or routine assessments, which summarize overall disease status including lung function, microbiology, and hospitalizations, a majority of clinicians reported using imaging. Both chest X-rays and CT scans were frequently employed, although practice varied widely in both modality and frequency. Imaging intervals ranged from annual to biennial or longer, underscoring the absence of consensus on optimal timing. Modality choice also differed by center type and size: chest X-rays were more commonly used in large centers, whereas CT scans were favored in pediatric and medium-sized centers. These differences likely reflect variation in resources, patient populations, and local practice norms.

Imaging use during exacerbations showed clear contrasts between oral and intravenous antibiotic-treated episodes. During exacerbations requiring oral antibiotics, most clinicians reported infrequent or occasional use of imaging. By contrast, during exacerbations requiring intravenous antibiotics, imaging was much more common, with chest X-rays used by nearly three-quarters of clinicians and CT scans by 16%. Adult centers were the most likely to report “always” using imaging, while pediatric centers reported more occasional use. These findings highlight a general tendency to escalate imaging with clinical severity, yet the lack of a standardized definition for exacerbations limits the translation of these results into actionable guidelines. Lucas et al. previously proposed an exacerbation definition for clinical trials that excluded imaging, focusing instead on home-based assessments.⁷ Developing a universally accepted definition that incorporates or clarifies the role of imaging will be critical for future guideline development.

MRI, increasingly recognized as a promising radiation-free imaging modality, was rarely used in clinical practice. Only a small number of clinicians, mainly in pediatric centers, reported its use during annual reviews, and almost none used it during exacerbations. Limited availability, high costs, and the need for specialized expertise likely restrict its broader application. In addition, MRI in young children often requires general anesthesia, which is longer and more demanding than sedation for CT, further limiting its feasibility despite its potential advantages for safe longitudinal monitoring.

Incorporating imaging data into PCD registries could substantially strengthen both clinical care and research. Current registries typically focus on lung function, microbiology, and hospitalization data.⁸ Adding standardized imaging time points and modalities would enhance these datasets, enabling more precise cross-center comparisons. Advances in artificial intelligence for automated quantification of structural lung disease further expand the potential for objective, reproducible imaging endpoints in clinical trials.^9–12

This survey highlights considerable variability in imaging practices across centers, underlining the need for consensus guidelines. The absence of standardized definitions for exacerbations remains a major barrier to consistent application of imaging data in clinical care and research. A Delphi consensus process, informed by these survey findings, represents a logical next step toward establishing international recommendations.

Several limitations to our study should be acknowledged. The study did not capture detailed information on upper airway imaging, despite the central role of sinonasal disease in PCD. Furthermore, as this was a self-reported survey, responses may reflect individual clinician preferences rather than institutional policy, introducing potential bias. Finally, this study did not assess clinical outcomes, and therefore the reported practices reflect clinician behavior but do not indicate the quality, appropriateness, or effectiveness of those approaches.

In summary, this international survey highlights substantial variation in airway imaging practices for PCD and provides a strong foundation for guideline development. Possible recommendations could include chest X-rays at diagnosis for children under 5 years and CT scans for older patients, with further consensus required regarding routine monitoring. Standardized imaging protocols would improve clinical care, support research, and enhance outcomes. Future work should address upper airway imaging, establish consistent definitions for exacerbations, and explore novel technologies such as MRI and AI to advance PCD management.

Conflicts of interest

None declared.

Funding

None declared.