# Clinical Value of Bronchiectasis and Airspace Enlargement Depicted on Iodine Map in Patients With Interstitial Lung Disease: A Pilot Study

## TL;DR

This pilot study shows that iodine maps in dual-energy CT scans better highlight bronchiectasis and airspace enlargement in interstitial lung disease patients compared to standard images.

## Contribution

The study introduces the clinical value of iodine maps in dual-energy CT for visualizing bronchiectasis and airspace enlargement in interstitial lung disease.

## Key findings

- Iodine maps showed more prominent bronchiectasis and airspace enlargement than monochromatic images.
- Progression of findings in iodine maps varied by interstitial lung disease subtype, such as usual interstitial pneumonia and rheumatoid arthritis.
- Dermatomyositis patients showed improvement in iodine map findings compared to monochromatic images.

## Abstract

Objectives

To investigate the degree and clinical meaning of bronchiectasis and airspace enlargement depicted on the iodine map in dual-energy CT pulmonary angiography of patients with interstitial lung disease, as a pilot study.

Methods

This retrospective study included 25 patients with interstitial lung disease who underwent dual-energy CT pulmonary angiography from November 2019 to February 2023. The iodine map and the 70 keV monochromatic image were reconstructed. Three readers independently evaluated the degree of bronchiectasis and airspace enlargement in the iodine map and monochromatic image. The time course of bronchiectasis and airspace enlargement was evaluated by comparing monochromatic images and follow-up conventional CT images for patients with follow-up CT examinations (n = 20).

Results

Bronchiectasis and airspace enlargement in the iodine map were significantly more prominent compared to monochromatic images for all readers (p ≤ 0.030). Patients with histopathologically proven usual interstitial pneumonia and those with rheumatoid arthritis showed image findings progressed in regions where bronchiectasis and airspace enlargement were rated as more prominent compared to monochromatic images by most readers. On the contrary, image finding was ameliorated in those regions in patients with dermatomyositis.

Conclusions

Bronchiectasis and airspace enlargement in the iodine map are depicted more prominently compared to the monochromatic image in dual-energy CT pulmonary angiography and have various time courses based on interstitial lung disease subtypes.