Editorial comment: cone-beam and phase contrast CT: new horizons in breast imaging?
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This Editorial Comment refers to the articles “Contrast-enhanced cone-beam breast-CT (CBBCT): clinical performance compared to mammography and MRI” by Wienbeck S et al, Eur Radiol. 2018 Mar 28. doi: 10.1007/s00330-018-5376-4 and “Diagnosis of breast cancer based on microcalcifications using grating-based phase contrast CT” by Li X et al, Eur Radiol. 2018 Jan 26. doi: 10.1007/s00330-017-5158-4
With an incidence of 12.3%, breast cancer constitutes the most frequent cancer in the normal female population . In Europe, 216,000 cases of breast cancer are newly diagnosed each year, with breast cancer being the second most common cause of death by cancer . The most important breast imaging technique is mammography, which has been shown to reduce relative mortality in the order of 30–35%. However, conventional mammography is hampered by several short-comings: (i) the relatively low sensitivity in patients with dense breast tissue, and (ii) the relatively low positive predictive value of microcalcifications resulting in a vast number of unnecessary biopsies.
A promising new technique is cone-beam computer-tomography of the breast (CBBCT) offering truly isotropic 3D images of the breast at high spatial resolution, which overcomes the short-coming of conventional mammography with the potential superimposition of breast cancer by dense breast tissue. Recently, Wienbeck et al  applied a CBBCT in a prospective study in 41 patients assessing 100 BIRADS 4 and 5 lesions. All included patients exhibited dense breast tissue (ACR type c or d). The authors compared contrast-enhanced CBBCT after the injection of iodinated contrast-agent (CE-CBBCT) with non-enhanced CBBCT (NC-CBBCT), conventional mammography and breast-MRI. The authors found a significantly higher diagnostic accuracy of CE-CBBCT compared to NC-CBBCT and conventional mammography almost reaching the accuracy of breast-MRI. Sensitivity of CE-CBBCT was 37–39% higher compared to conventional mammography. A limitation of the presented study is the lack of a comparison with digital breast tomosynthesis, which is a pseudo-3D technique reducing the overlap with dense breast tissue. Another limitation of the current CE-CBBCT imaging technique is the fact that only one breast may be imaged at once, which is not an issue in breast-MRI. As the device can only depict one breast within one scan, and contrast-agent can only be administered once during an examination, only one side can be depicted during one session, and examination of both breasts requires a second appointment.
Regarding the relatively low specificity of microcalcifications for prediction of breast cancer, one new promising technique is the phase-contrast measurement in X-ray breast examinations. In a study by Wang et al , the application of phase-contrast X-ray mammography for the classification of microcalcifications was proposed. In phase-contrast the complementary nature of absorption and small-angle scattering signals are used to obtain a more comprehensive characterization of microcalcifications. Technically, an X-ray grating interferometer is applied on a conventional X-ray tube. In a recent study by Li et al , a CT-based method was applied for phase-contrast imaging of microcalcifications. In a Talbot-Lau interferometer setup, 21 specimens from 20 patients were examined, with 11 specimens from benign breast diseases and 10 specimens from invasive-ductal carcinoma or ductal carcinoma in situ. Li et al report a significantly higher accuracy of phase-contrast imaging for the classification microcalcifications compared to projection images.
Altogether, there are several interesting new techniques on the horizon, which will provide a notable improvement of sensitivity and specificity in breast imaging using X-ray techniques, thereby allowing for significantly shorter examination times as compared to the current gold standard of breast MRI. CBBCT is already a commercially available technique, whereas phase-contrast mammography is still at the stage of development.
The authors state that this work has not received any funding.
Compliance with ethical standards
The scientific guarantor of this publication is Andreas Boss
Conflict of interest
The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.
Statistics and biometry
No complex statistical methods were necessary for this paper.
Written informed consent was not required for this study because this is an editorial without any study subjects.
Institutional Review Board approval was not required because this is an editorial without any study subjects.
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