Photon-counting CT matched breast MRI for local staging and beat it on nodes, but missed calcifications

Design

Prospective single-centre diagnostic study with pathological reference

Population

126 women with BI-RADS 4C or higher breast lesions

Primary outcome

Agreement and accuracy of PCCT vs MRI, mammography and PET/CT

Effect

T category kappa 0.86 to 0.88 vs MRI; nodal sensitivity +10% (1 to 20) vs MRI; 44% of microcalcifications missed

This prospective study enrolled 126 women with BI-RADS 4C or higher breast lesions on ultrasound or mammography, who had both breast MRI and multiphasic contrast-enhanced photon-counting CT; a locally advanced subset also had FDG PET/CT. Four radiologists read independently, with pathology as the reference.

Photon-counting CT agreed well with MRI on lesion characterisation and T category (kappa 0.86 to 0.88) and correlated best with pathological size. For 46 pathologically confirmed additional lesions, it was 44 percentage points more sensitive than mammography and similar to MRI (difference 7%, 95% CI -5 to 21). For nodal metastases it was more sensitive than MRI (difference 10%, 1 to 20) and agreed with PET/CT on N category (kappa 0.82, n = 19). It missed 44% of microcalcifications that mammography showed.

This is a feasibility study from one centre over three months. It suggests photon-counting CT could offer local and nodal staging in one examination for women who cannot have MRI, but it does not replace mammography for calcifications.

• Photon-counting CT may be an alternative for local staging in women who cannot have breast MRI
• Keep mammography in the work-up; CT missed almost half of microcalcifications
• Nodal assessment was a relative strength of photon-counting CT
• Weigh radiation and iodinated contrast against MRI when choosing a staging test

Why it matters

It raises the possibility of one-stop local, nodal and distant staging on a single scanner.

Don't overread it

A single-centre feasibility study of 126 women with high-suspicion lesions; it is not yet a basis for changing staging pathways.

The statistics, in plain English

Kappa measures agreement beyond chance; above 0.8 is very good. The additional-lesion comparison with MRI (7%, -5 to 21) crosses zero, so no difference was shown.

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