Comparative Diagnostic Efficacy of CBBCT, MRI, Ultrasound and Combined Modalities for Mass Enhancement Breast Lesions

Technical Summary: Comparative Diagnostic Efficacy of CBBCT, MRI, Ultrasound, and Combined Modalities for Mass Enhancement Breast Lesions

Problem Statement
Breast cancer remains the leading cause of cancer-related mortality among women globally. While mammography (MG) and ultrasound (US) are standard screening tools, and Magnetic Resonance Imaging (MRI) serves as a critical supplementary diagnostic modality, limitations persist. MG is often limited by patient discomfort and tissue density; MRI offers high accuracy but is constrained by high costs, long scan times, claustrophobia, and contraindications for patients with renal impairment or metal implants. Cone-beam breast CT (CBBCT) has emerged as a novel 3D imaging technology offering high spatial resolution and patient comfort without breast compression. However, existing literature predominantly compares CBBCT with MG, leaving a gap in comparative data regarding its efficacy against US and MRI, particularly for mass enhancement lesions. This study aims to evaluate the diagnostic value of CBBCT, MRI, and US, both individually and in combination, using pathological results as the gold standard.

Methodology
This prospective study analyzed data from 66 female patients (85 total lesions: 32 benign, 53 malignant) examined between June 2020 and April 2023 at the Chinese PLA General Hospital.

• Imaging Protocols:
  • CBBCT: Performed using a KBCT-1000 system. Patients were positioned prone with the breast suspended. Scans included non-contrast (NC-CBBCT) and contrast-enhanced (CE-CBBCT) phases using Iohexol. The system acquired 300 projections in 10 seconds via 360° rotation.
  • MRI: Conducted on a GE 3.0T scanner with an 8-channel breast coil. Protocols included T1WI, fat-suppressed T2WI, DWI, and dynamic contrast-enhanced (DCE) MRI using Gadopentetate dimeglumine.
  • Ultrasound (US): Included conventional grayscale, Color Doppler Flow Imaging (CDFI), and Contrast-Enhanced US (CEUS) for select cases using SonoVue.
• Analysis: Two radiologists independently reviewed CBBCT and MRI images, while US was evaluated by a sonologist and attending physician. Lesions were classified using adapted BI-RADS criteria (Malignant: BI-RADS 4–5; Benign: ≤3 for CBBCT/MRI; ≤4A for US).
• Statistical Approach: Sensitivity, specificity, and Area Under the Curve (AUC) were calculated for individual modalities and combined approaches (CBBCT+US, MRI+US, and all three). Pathological diagnosis served as the reference standard.

Key Contributions

• Direct Comparative Analysis: This study provides one of the first direct comparisons of CBBCT against both US and MRI for breast mass lesions, addressing a critical gap in current literature.
• Evaluation of Combined Modalities: It assesses the diagnostic efficacy of combining CBBCT with US, demonstrating its potential as a viable alternative to the MRI+US combination.
• Quantitative Metrics: The study establishes specific diagnostic performance metrics (sensitivity, specificity, AUC) for CE-CBBCT in the context of mass enhancement lesions, including detailed analysis of lesion shape, margins, and enhancement kinetics (ΔCT values).

Results

• Detection Rates: US and MRI achieved 100% detection rates (85/85). CE-CBBCT demonstrated a high detection rate of 92.94% (79/85), significantly outperforming NC-CBBCT (70.59%). The missed diagnoses in CE-CBBCT were primarily small benign adenosis and one malignant mucinous micropapillary carcinoma.
• Diagnostic Accuracy:
  • Sensitivity: MRI (100%) and the combined CBBCT+US (98.07%) and CBBCT+US+MRI (100%) groups showed the highest sensitivity. CBBCT alone was 92.31%, and US alone was 88.46%.
  • Specificity: CBBCT (74.07%) and US (77.78%) demonstrated higher specificity than MRI (48.15%). The combined CBBCT+US approach achieved a specificity of 88.89%.
  • AUC: The combined CBBCT+US approach yielded an AUC of 0.958, which was statistically comparable to MRI+US (0.960) and superior to US alone (0.891).
• Imaging Features: Significant differences were observed in lesion shape classification between US and the other modalities. CE-CBBCT and MRI showed high consistency in assessing margins and size. Malignant lesions exhibited significantly higher mean ΔCT values (106.9 ± 43.0 HU) compared to benign lesions (65.3 ± 30.7 HU).

Significance and Claims
The authors conclude that CBBCT possesses good diagnostic performance for breast mass lesions. When combined with ultrasound, CBBCT serves as a potential alternative to MRI, offering diagnostic efficacy comparable to the MRI+US combination (AUC 0.958 vs. 0.960). This combination is particularly significant for patients with contraindications to MRI (e.g., claustrophobia, renal impairment). The study highlights that CBBCT offers advantages in patient comfort, rapid scanning, and lower costs compared to MRI, while maintaining high sensitivity and specificity when used in conjunction with US. The authors note that while CBBCT is a promising tool, its role requires further validation through large-scale, multi-center studies with diverse lesion types.