Does Photon-Counting CT Offer Better Detection of Lymph Node Metastasis than Breast MRI?
Comparing PCCT and MRI for detection of lymph node metastasis, the study authors determined that PCCT offered higher sensitivity (78 percent vs. 69 percent), comparable specificity (88 percent vs. 85 percent) and higher positive predictive value (PPV) (77 percent vs. 69 percent).
“In this study, PCCT provided better nodal assessment results than MRI, likely because of the broader field of view of PCCT, including the axillary, internal mammary, and supraclavicular regions,” added Fu and colleagues.
Which Is Better at Detecting Suspicious Calcifications: PCCT or Full-Field Digital Mammography?
However, PCCT offered weaker performance than FFDM with detection of suspicious calcifications. While FFDM findings of suspicious calcifications corresponded to 50 out of 54 lesions (92.6 percent), the researchers found that PCCT missed 44 percent of suspicious calcifications detected with FFDM.
Three Key Takeaways
• PCCT rivals MRI for lesion detection and nodal staging. In this 126-patient study, PCCT showed sensitivity for additional lesions comparable to breast MRI (65 percent vs. 57 percent) and far superior to full-field digital mammography (FFDM) (21 percent). For lymph node metastasis, PCCT actually outperformed MRI on sensitivity (78 percent vs. 69 percent) and PPV (77 percent vs. 69 percent), likely due to its wider field of view covering axillary, internal mammary, and supraclavicular regions.
• Calcification detection remains a weak point for PCCT. FFDM still outperforms PCCT for suspicious calcifications. PCCT missed 44 percent of calcifications that FFDM detected. This suggests PCCT shouldn't replace mammography for calcification assessment at least with current reconstruction protocols.
• Clinical validation is still preliminary. BI-RADS criteria aren't yet validated for PCCT and protocol variability (e.g., prone positioning to match MRI) may limit reproducibility across sites. Accordingly, these findings, while promising, need confirmation in larger studies before PCCT can be adopted as a standard preoperative tool in this patient population.
Noting that variability in image reconstruction parameters and smaller sample size may have affected the results with calcifications, the study authors maintained that subsequent studies may provide greater clarity.
“Accurate assessment of microcalcification size and distribution remains challenging, as tomographic CT differs from planar FFDM. Future research should investigate optimized reconstruction algorithms and convolutional neural network–based ultrahigh-resolution enhancement to improve detectability,” posited Fu and colleagues.
Final Notes
(Editor’s note: For related content, see “Can Contrast-Enhanced Mammography Improve Breast Cancer Staging?: Nine Takeaways from a New Literature Review,” “Moving Beyond Mammography for Screening and Staging of Invasive Lobular Carcinoma” and “Current Perspectives on PET/CT Imaging in Patients with Metastatic Breast Cancer.”)
In regard to study limitations, the authors acknowledged that the BI-RADS system is not currently validated for PCCT application. While noting that prone patient positioning was emphasized for PCCT scans in order to match breast MRI scans, they conceded that protocol variations may have an impact on broader applicability across multiple facilities.
