Spectral CT helps call intrapancreatic accessory spleen on a single portal venous phase

Design

Retrospective single-centre diagnostic accuracy study

Population

85 patients with hypervascular pancreatic lesions (34 accessory spleen, 51 neoplasms)

Primary outcome

Discrimination of intrapancreatic accessory spleen from neoplasm

Effect

Reader accuracy 88.1% with spectral vs 60.7% conventional; iodine density AUC 0.96

An intrapancreatic accessory spleen can look like a hypervascular pancreatic neuroendocrine tumour, and the distinction often needs further tests. This retrospective study examined 85 patients with hypervascular pancreatic lesions on portal venous phase spectral CT: 34 accessory spleens and 51 neoplasms, including 22 neoplasms in the pancreatic tail.

The authors compared each lesion's values with the spleen's on several spectral reconstructions. Conventional images gave an AUC of about 0.80, while 40-keV monoenergetic images, iodine density and effective atomic number maps reached 0.95 to 0.97 overall and up to 0.99 for tail lesions. When three radiologists added spectral images to conventional ones for tail lesions, pooled sensitivity rose from 61.8% to 86.3%, specificity from 59.1% to 90.9%, and accuracy from 60.7% to 88.1%, with better agreement between readers.

The study is small, single-centre and retrospective, and the lesions had already been selected as hypervascular. It needs external validation before it replaces confirmatory tests.

Where spectral CT is available, comparing a tail lesion's iodine and effective atomic number values with the spleen's is a quick step that may avoid an unnecessary further work-up.

• For a hypervascular pancreatic tail lesion, compare its spectral values with the spleen's on the same scan.
• Use iodine density or effective atomic number maps where spectral data are available.
• Treat a close match as supportive of accessory spleen, not as a final diagnosis.
• Consider confirmatory testing where the spectral match is imperfect or the lesion is outside the tail.

Why it matters

Mistaking an accessory spleen for a neuroendocrine tumour can lead to unnecessary tests or even surgery.

Don't overread it

This was a small retrospective study at one centre; the performance figures need external validation.

The statistics, in plain English

An AUC of 0.97 means the measure ranked an accessory spleen above a neoplasm 97% of the time in this sample. Small single-centre studies often show higher accuracy than later validation studies do.

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