Photon-counting detector CT for CT pulmonary angiography: a systematic review and meta-analysis

To systematically evaluate the radiation dose, contrast media utilisation, image quality, and diagnostic performance of photon-counting detector CT (PCCT) versus energy-integrating detector CT (EID-CT) in CT pulmonary angiography (CTPA).

PubMed, Web of Science, and Cochrane CENTRAL were searched to March 10, 2026. Studies comparing PCCT with EID-CT or reporting PCCT-based CTPA were included. Random-effects meta-analyses evaluated CT dose index volume (CTDIvol), total iodine load (TIL), SNR, and CNR. Sensitivity analyses used the Hartung-Knapp adjustment.

Twelve studies (950 patients) were included. Radiation dose (5 studies, 854 patients) and contrast load (2 studies, 322 patients) were significantly lower with PCCT under standard models: pooled CTDIvol mean difference (MD) was -2.85 mGy (95% CI -5.52 to -0.18) and total iodine load MD was -5.62 gI (95% CI -9.34 to -1.89) (both p < 0.05). However, neither was significant under Hartung-Knapp adjustment (p = 0.113 for CTDIvol; p = 0.208). SNR and CNR showed no significant differences. For chronic thromboembolic disease (2 studies, 109 patients), the pooled sensitivity and specificity of PCCT iodine maps were 92.3% (95% CI 85.4-96.1%) and 83.4% (95% CI 75.2-89.3%), respectively.

PCCT-based CTPA shows potential to reduce radiation dose and contrast load versus EID-CT while maintaining image quality. However, under Hartung-Knapp adjustment, differences were not significant, requiring cautious interpretation under high heterogeneity.

Question Does photon-counting detector CT (PCCT) reduce radiation dose and contrast media volume in CT pulmonary angiography (CTPA) for pulmonary embolism compared to energy-integrating detector CT? Findings While PCCT-based CTPA shows significant reductions in radiation dose and iodine load under standard random-effects models, these benefits were not statistically significant under conservative sensitivity analyses (Hartung-Knapp adjustment) due to high protocol heterogeneity. Clinical relevance PCCT-based CTPA has the potential to allow for lower radiation dose and contrast media utilisation, which could help minimise the risks of radiation exposure and contrast-induced nephropathy in vulnerable patients, though protocol standardisation is required to confirm these benefits.