New study finds low-dose CT scans useful for tracking CF therapy
Lower-radiation imaging captured lung changes after treatment
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Low- and ultra-low-dose lung CT scans may help monitor how people with cystic fibrosis (CF) respond to CFTR modulator therapies while using less radiation, a study in Italy suggests.
After starting Trikafta (ivacaftor, tezacaftor, and elexacaftor), patients showed a nearly 50% reduction in airway thickening and a 73% decrease in mucus buildup, as measured by CT scans performed with substantially lower radiation doses than standard scans.
Researchers say low-dose CT can track treatment response
According to the researchers, “in combination with clinical markers, low- and ultra-low-dose CT protocols currently represent the gold standard for assessing CF therapy with CFTR modulators.”
The study, “Short-term monitoring of CFTR modulator therapy in adults and children with cystic fibrosis using low and ultra-low-dose lung CT,” was published in La radiologia medica.
CF is caused by genetic mutations that result in the loss or dysfunction of the CFTR protein, leading to the buildup of thick, sticky mucus in organs, particularly the lungs.
CFTR modulators, such as Trikafta, are designed to improve CFTR function in people with specific disease-causing mutations. Imaging tests, such as CT scans, can be used to assess disease progression and treatment effects.
In this study, researchers at a hospital in Rome, Italy, investigated whether low-dose and ultra-low-dose lung CT scans could be used to monitor treatment response in people with CF. Changes over up to 18 months were compared with clinical measures, including forced expiratory volume in 1 second (FEV1), a measure of lung function, and the sweat chloride test.
“Recent advances in low-dose and ultra-low-dose CT protocols may enable more frequent imaging with reduced radiation exposure, enhancing monitoring of disease progression,” the scientists wrote.
Study tests low- and ultra-low-dose CT scans in patients
The study included 15 children (ages 11 to 18) and 15 adults (ages 21 to 57), including 24 females and six males. Children underwent an ultra-low-dose CT protocol with a mean radiation dose of 0.56 millisievert (mSv), while adults received a low-dose CT protocol with a mean dose of 2.4 mSv.
The severity and extent of lung damage were assessed using the Brody II score, a widely used CT scoring system, based on both qualitative and quantitative analyses.
At the start of the study, participants had a mean Brody score of 96, indicating moderate-to-severe lung damage. After starting Trikafta, the score decreased by nearly half, to a mean of 50, indicating a significant improvement.
Quantitative analysis of CT images also showed significant improvements across all measured parameters after treatment. The most significant effect was a 73% reduction in mucus buildup in the lungs. Patients also showed a 51% reduction in airway wall thickening and a 44% decrease in air trapping — when air remains in the lungs after breathing out. Bronchiectasis, a condition marked by permanently widened airways, was reduced by about 34% overall and by 42% in children.
Lung function and sweat test results improved after treatment
Clinical parameter analyses further supported these findings, with patients experiencing a significant increase in FEV1, the amount of air a person can forcefully exhale in one second (1.94 vs. 2.52 L). Participants also experienced a significant decrease in sweat chloride (95 vs. 45 milliequivalents per liter), a marker of CFTR protein function.
In addition, changes in the Brody score were significantly associated with improvements in FEV1 and sweat chloride after treatment.
Overall, “by reducing both radiation exposure and the frequency of scans, these protocols significantly lower radiological risk while offering comprehensive, detailed, and—crucially—repeatable follow-up for both adult and pediatric patients,” the investigators wrote.
The researchers noted that the study included a small number of participants, “a consequence of both the relatively recent introduction of CFTR modulator therapies and the inherent rarity of CF,” particularly among younger patients.
