Imaging differentiates IPAS from Hypervascular Pancreatic Neoplasms

A retrospective study that spectral imaging may facilitate differentiation of intrapancreatic accessory spleen (IPAS) from hypervascular pancreatic neoplasms (HPN) using only portal-venous-phase (PVP) CT.

Researchers found that the addition of spectral imaging improved visual differentiation by highlighting differences between pancreatic neoplasms and the spleen.

Assessing Spectral Imaging

Researchers included participants who underwent multiphase contrast-enhanced abdominal spectral CT between January 2018 and June 2025 and had hypervascular pancreatic lesions during PVP.

85 patients were included, among them 34 lesions were classified as IPAS, with 51 lesions as hypervascular neoplasms.

Hypervascular pancreatic lesions were defined as enhancing soft-tissue lesions that visually showed higher attenuation than the adjacent pancreatic parenchyma on conventional PVP CT.

All scans were performed on a dual-layer spectral-detector CT, and the diagnosis of IPAS was determined based on either histopathological confirmation or clinical and imaging findings.

Diagnosis of IPAS was determined based on either histopathological confirmation or clinical and imaging findings, and three radiologists independently performed visual assessments, blinded to all clinical information and final diagnoses.

IPAS Differentiated from Hypervascular Pancreatic Neoplasms

IPAS showed lower attenuation on conventional images, as well as lower iodine density than non-IPAS lesions.

For lesion density measurements the area under the curve (AUC) of conventional images was 0.697, while those of spectral imaging ranged from 0.504 to 0.766. Across all image series, relative lesion-to-spleen ratio (RLSR) yielded higher AUCs than lesion density.

RLSR achieved higher diagnostic performance than lesion density measurements alone and conventional plus spectral imaging showed higher diagnostic performance and interobserver agreement than conventional imaging alone.

Implications of Spectral Imaging

Researchers concluded that, spectral imaging may facilitate the differentiation of IPAS from hypervascular pancreatic neoplasms on routine portal venous–phase CT, suggesting that spectral CT can play a role in evaluating incidental hypervascular pancreatic lesions that would otherwise remain indeterminate on conventional CT.

Further studies in independent cohorts, including studies using other dual-energy CT platforms and photon-counting CT systems, are needed to confirm these findings and to determine the independent visual diagnostic contribution of each spectral reconstruction, which could not be evaluated because the visual assessment integrated conventional and spectral imaging across multiple image series.

Reference :

Nagayama Y et al. Spectral imaging for differentiating intrapancreatic accessory spleen from hypervascular pancreatic neoplasms using single-phase post-contrast CT. Eur Radiol.2026.DOI: 10.1007/s00330-026-12924-7.