In this selected cohort, pulmonary infarction occurred only in segments with subsegmental emboli, which showed reduced peripheral iodine concentration on spectral CT iodine maps, suggesting that spectral CT-derived peripheral iodine concentration may provide functional information on regional hypoperfusion in acute pulmonary embolism.
Key Findings
Results
Pulmonary infarction occurred exclusively in lung segments affected by subsegmental emboli and was not observed in any segments without subsegmental emboli.
The study included 31 patients with SCTPA-confirmed acute PE and at least one pulmonary infarction, and 31 controls without PE or PI.
A total of 440 embolic occlusions were identified across all patients.
PI was found exclusively in segments affected by SSE in this selected cohort.
No PI was observed in segments without subsegmental emboli.
Results
Subsegmental emboli were independently associated with significantly reduced peripheral iodine concentration in mixed-effects modelling.
In mixed-effects modelling, SSE were independently associated with reduced pIC (β = -0.706, p < 0.001).
Segmental emboli were also independently associated with lower pIC (β = -0.137, p < 0.001).
Lobar and central emboli showed no significant independent associations with peripheral iodine concentration.
The stronger effect size for SSE (β = -0.706) compared to segmental emboli (β = -0.137) suggests SSE have a disproportionately greater impact on peripheral perfusion.
Results
The Mastora score showed a moderate correlation with the number of manifest pulmonary infarctions.
The Mastora score, which assesses embolic burden, showed a moderate correlation with the number of manifest pulmonary infarctions (ρ = 0.566, p = 0.011).
This correlation was statistically significant, indicating that greater embolic burden was associated with more pulmonary infarctions.
The correlation was characterised as 'moderate,' suggesting embolic burden alone does not fully predict infarction.
Results
Peripheral iodine concentration quantified on spectral CT iodine maps reflects regional hypoperfusion and provides functional information on lung perfusion in acute pulmonary embolism.
pIC was quantified in standardised subpleural regions of interest in each lung segment.
This retrospective single-centre study included 62 patients total.
Spectral CT pulmonary angiography (SCTPA) enabled quantitative perfusion analysis using iodine maps, which conventional CTPA cannot provide.
The authors conclude that 'quantitative pIC reflects regional hypoperfusion and provides functional information on lung perfusion in acute PE.'
Background
Conventional CTPA provides high-resolution morphological imaging but does not permit direct functional assessment of regional lung perfusion, a limitation addressed by spectral CT.
The study was motivated by the incomplete understanding of the relationship between peripheral perfusion impairment, subsegmental emboli, and pulmonary infarction.
The study design was a retrospective single-centre analysis, which limits generalisability.
What This Means
This research suggests that a newer type of CT scan called spectral CT can provide useful functional information about blood flow in the lungs of patients with pulmonary embolism (PE), a condition where blood clots block vessels in the lungs. By measuring iodine concentration in the outer (peripheral) regions of the lung on special iodine maps generated by the scanner, doctors can identify areas where blood flow is reduced. The study found that in this group of 62 patients, lung tissue death (pulmonary infarction) only occurred in lung segments that also had clots in the smallest, most peripheral vessels (called subsegmental emboli), and these segments had significantly lower peripheral iodine concentration compared to unaffected areas.
A key finding is that subsegmental emboli — which are smaller clots that can be harder to detect and are sometimes considered less dangerous — had a much stronger association with reduced peripheral blood flow than larger, more centrally located clots. This challenges assumptions about clot size and clinical significance, suggesting that the location of a clot (near the lung tissue) may matter more than its size when it comes to causing lung damage. The overall clot burden score (Mastora score) also moderately correlated with the number of infarctions, supporting the idea that more extensive clotting leads to more lung injury.
This research suggests that spectral CT could improve how doctors evaluate and understand lung damage in pulmonary embolism by adding functional perfusion information to the standard anatomical images. Being able to see which lung regions are actually receiving less blood — not just where clots are located — could potentially help clinicians better assess the severity and consequences of pulmonary embolism. However, as a small retrospective single-centre study, these findings would need to be confirmed in larger prospective studies before they could change clinical practice.
Horr A, Aludin S, Schmill L, Mostafa K, Walther I, Schunk D, et al.. (2026). Spectral CT-derived peripheral iodine concentration in acute pulmonary embolism: association with subsegmental emboli and pulmonary infarction.. European radiology experimental. https://doi.org/10.1186/s41747-026-00784-1