Perfusion Patterns of Pleura-Based Pulmonary Sarcoma Metastases on Contrast-Enhanced Ultrasound (CEUS): A Single-Center Retrospective Pilot Study

Background/Objectives: Pleura-based pulmonary nodules in soft-tissue sarcoma (STS) patients remain diagnostically challenging, and entity-specific contrast-enhanced ultrasound (CEUS) data are scarce. We aimed to characterize CEUS perfusion patterns of pleura-based STS pulmonary metastases in a pilot cohort. Methods: We investigated a single-center retrospective cohort at a tertiary STS referral center (Dec 2024–Dec 2025). Of 51 consecutive STS patients with suspected pulmonary metastases screened, 32 lacked pleural contact and 6 were excluded for logistical reasons; the remaining 13 underwent standardized CEUS of a pleura-contacting lesion (≥5 mm) visible on B-mode lung ultrasound (B-LUS), with 1 excluded on biopsy (anaplastic lymphoma). The reference standard combined histology, therapy-related size reduction of the index lesion, and/or documented distant metastatic STS. Two readers rated all examinations independently, with adjudication by a third senior reader. Wilson 95% confidence intervals (CIs) and Cohen’s κ were computed. Results: In the 12 analyzed patients (mean age 58.8 ± 17.8 years; 7 male), the index lesion was histologically confirmed in 4 (33.3%). On CEUS, bronchial-arterial (BA) enhancement predominated (10/12; 83.3%, 95% CI 55.2–95.3%) and pulmonary-arterial timing occurred in 2/12 (16.7%). Marked enhancement was present in 9/12 (75.0%), homogeneous in 8/12 (66.7%), and rapid washout (<120 s) in all lesions (12/12; 100%, 95% CI 75.8–100%). Inter-reader agreement was substantial to almost perfect for the diagnostically relevant CEUS perfusion variables (enhancement κ = 0.75; EE κ = 0.80; HE κ = 0.82) and moderate for the descriptive shape variable (Form κ = 0.47). Conclusions: In this selected pilot cohort, pleura-based STS lung metastases most commonly showed BA-dominant enhancement with universal rapid washout. The findings are hypothesis-generating and require validation in larger, prospective multicenter cohorts.