- The disease
- Post-acute sequelae of SARS-CoV-2 infection (sometimes called long COVID) describes a range of persistent symptoms, including breathlessness and fatigue, that continue after the acute infection has resolved (per ClinicalTrials.gov NCT05866952). Standard chest imaging often appears normal in these patients despite ongoing symptoms, making it difficult to identify the underlying lung abnormality. The NCT05866952 trial focuses specifically on detecting ventilatory and perfusion (airflow and blood-flow) abnormalities in this population. A separate, earlier trial (NCT04880551) examined ventilation imbalances in mild-to-moderate chronic obstructive pulmonary disease (COPD), a progressive lung condition affecting airflow.
- What the asset is trying to do
- CT:VQ is a software-based diagnostic tool that analyses standard computed tomography (CT) chest scan data to generate maps of how air moves through the lungs during breathing (ventilation, V) and how blood flows through the lungs (perfusion, Q). The approach builds on 4DMedical's earlier X-ray velocimetry technology, which used fluoroscopic imaging to measure lung motion (per ClinicalTrials.gov NCT04489758, NCT04892719). Unlike nuclear medicine VQ scans, which require radioactive tracers, CT:VQ derives functional information from imaging modalities already in routine clinical use.
- What the trial is measuring, and why it matters
- The lead trial (NCT05866952) measures ventilatory and perfusion abnormalities detected by CT imaging in individuals with post-acute COVID-19 conditions, with a primary completion date of 2026-05-31 (per ClinicalTrials.gov NCT05866952). The trial targets 40 participants and focuses on identifying and characterising functional lung defects that may not be visible on conventional anatomical imaging. Demonstrating that the tool can reliably detect such defects in this population is the central scientific question.
- Efficacy benchmarks in this setting
- For conventional nuclear medicine ventilation-perfusion (VQ) scintigraphy, published studies report sensitivity and specificity for pulmonary embolism diagnosis of approximately 77-98% and 38-98% respectively depending on protocol and population, though these figures apply to a different indication than the post-COVID setting studied here (Sostman et al, Radiology 2008 and PIOPED II data are frequently cited benchmarks). In the post-acute COVID-19 imaging literature, CT perfusion abnormalities have been documented in symptomatic patients in observational cohorts, but no uniformly accepted diagnostic standard currently exists for this specific application (). CT:VQ's figures from early or ongoing studies are not statistically comparable to approved-modality benchmarks given differences in study design, patient population, and endpoint definitions.
- Commercial context
- No CT-based ventilation-perfusion software tool currently holds a specific regulatory approval for the post-acute COVID-19 functional imaging indication being studied in NCT05866952 (). 4DMedical announced the acquisition of contextflow to create a European Union platform (per ASX announcement 2026-05-31), which is described as expanding the company's European presence. CT:VQ is the company's lead imaging asset based on its pipeline disclosures (). No specific commercial deal values, licensing terms, or manufacturing cost figures have been disclosed in the provided source material.