# Ultra-low-dose computed tomography and chest X-ray in follow-up of high-grade soft tissue sarcoma—a prospective comparative study

## TL;DR

This study compares ultra-low-dose CT and chest X-ray for detecting lung metastases in soft tissue sarcoma patients, showing CT is more sensitive with low radiation.

## Contribution

ULD-CT is shown to be more sensitive than CXR for detecting pulmonary metastases in sarcoma follow-up with minimal radiation exposure.

## Key findings

- ULD-CT detected all nine cases of asymptomatic lung metastases, while CXR only detected three.
- The median effective dose of ULD-CT was 0.27 mSv, significantly lower than conventional CT.
- Eight out of nine patients with metastases died of the disease despite early detection.

## Abstract

Ultra-low-dose computed tomography (ULD-CT) may combine the high sensitivity of conventional computed tomography (CT) in detecting sarcoma pulmonary metastasis, with a radiation dose in the same magnitude as chest X-ray (CXR). Fifty patients with non-metastatic high-grade soft tissue sarcoma treated with curative intention were recruited. Their follow-up involved both CXR and ULD-CT to evaluate their different sensitivity. Suspected findings were confirmed by conventional CT if necessary. Patients with isolated pulmonary metastases were treated with surgery or stereotactic body radiation therapy (SBRT) with curative intent if possible. The median effective dose from a single ULD-CT study was 0.27 mSv (range 0.12 to 0.89 mSv). Nine patients were diagnosed with asymptomatic lung metastases during the follow-up. Only three of them were visible in CXR and all nine in ULD-CT. CXR had therefore only a 33% sensitivity compared to ULD-CT. Four patients were operated, and one had SBRT to all pulmonary lesions. Eight of them, however, died of the disease. Two patients developed symptomatic metastatic recurrence involving extrapulmonary sites+/−the lungs between two imaging rounds. ULD-CT has higher sensitivity for the detection of sarcoma pulmonary metastasis than CXR, with a radiation dose considerably lower than conventional CT.

Clinical trial registration: NCT05813808. 04-14-2023.