Impact on the recall rate of digital breast tomosynthesis as an adjunct to digital mammography in the screening setting. A double reading experience and review of the literature.

OBJECTIVES: To estimate the impact on recall rate (RR) of digital breast tomosynthesis (DBT) associated with digital mammography (DM+DBT), compared to DM alone, evaluate the impact of double reading (DR) and review the literature. METHODS: Ethics committees approved this multicenter study. Patients gave informed consent. Women recalled from population-based screening reading were included. Reference standard was histology and/or ≥ 1 year follow up. Negative multiple assessment was considered for patients lost at follow up. Two blinded readers (R1, R2) evaluated first DM and subsequently DM+DBT. RR, sensitivity, specificity, accuracy, positive and negative predictive values (PPV, NPV), were calculated for R1, R2, and DR. Cohen κ and χ(2) were used for R1-R2 agreement and RR related to breast density. RESULTS: We included 280 cases (41 malignancies, 66 benign lesions, and 173 negative examinations). The RR reduction was 43% (R1), 58% (R2), 43% (DR). Sensitivity, specificity, accuracy, PPV and NPV were: 93%, 67%, 71%, 33%, 98% for R1; 88%, 73%, 75%, 36%, 97% for R2; 98%, 55%, 61%, 27%, 99% for DR. The agreement was higher for DM+DBT (κ=0.459 versus κ=0.234). Reduction in RR was independent from breast density (p=0.992). CONCLUSION: DBT was confirmed to reduce RR, as shown by 13 of 15 previous studies (reported reduction 6-82%, median 31%). This reduction is confirmed when using DR. DBT allows an increased inter-reader agreement.

Breast cancer detection using double reading of unenhanced MRI including T1-weighted, T2-weighted STIR, and diffusion-weighted imaging: a proof of concept study.

OBJECTIVE: The purpose of this study was to investigate the diagnostic performance of unenhanced MRI in detecting breast cancer and to assess the impact of double reading. MATERIALS AND METHODS: A total of 116 breasts of 67 women who were 36-89 years old were studied at 1.5 T using an unenhanced protocol including axial T1-weighted gradient-echo, T2-weighted STIR, and echo-planar diffusion-weighted imaging (DWI). Two blinded readers (R1 and R2) independently evaluated unenhanced images using the BIRADS scale. A combination of pathology and negative follow-up served as the reference standard. McNemar and kappa statistics were used. RESULTS: Per-breast cancer prevalence was 37 of 116 (32%): 30 of 37 (81%) invasive ductal carcinoma, five of 37 (13%) ductal carcinoma in situ, and two of 37 (6%) invasive lobular carcinoma. Per-breast sensitivity of unenhanced MRI was 29 of 37 (78%) for R1, 28 of 37 (76%) for R2, and 29 of 37 (78%) for double reading. Specificity was 71 of 79 (90%) for both R1 and R2 and 69 of 79 (87%) for double reading. Double reading did not provide a significant increase in sensitivity. Interobserver agreement was almost perfect (Cohen κ = 0.873). CONCLUSION: An unenhanced breast MRI protocol composed of T1-weighted gradient echo, T2-weighted STIR, and echo-planar DWI enabled breast cancer detection with sensitivity of 76-78% and specificity of 90% without a gain in sensitivity from double reading.

Contrast enhanced breast MRI: spatial displacement from prone to supine patient's position. Preliminary results.

OBJECTIVE: To estimate the spatial displacement of breast lesions and nipples in MR images when the patient is moved from the standard prone to a supine position close to ultrasound (US) or surgical setting. MATERIALS AND METHODS: Eleven patients underwent breast MRI in prone position with dynamic 3D T1-weighted sequences using 0.1 mmol/kg gadobenate dimeglumine. Subsequently, the patient was repositioned in supine position and a 3D volumetric interpolated breathhold examination sequence was acquired using a thoracic surface coil. For both positions we measured the following minimal distances: (A) from lesion margin to the coronal plane passing through the anterior surface of the sternum, antero-posterior, on native axial images; (B) from lesion margin to the medial sagittal plane, on native axial images, latero-medial; (C) from lesion margin to the axial plane passing through the tracheal bifurcation, cranio-caudal; (D) from lesion margin to the thoracic wall/pectoral muscle, on native axial images; (E) from lesion margin to the skin, on native axial images; (F) from lesion margin to the base of the nipple, on oblique reconstructions. Measurements from A to D were also obtained for each nipple. The prone-to-supine spatial displacement was calculated as the absolute difference between the measurement obtained in supine position and the same measurement obtained in prone position. Displacements were presented as mean ± standard deviation and median in parenthesis. RESULTS: Lesion displacements were (mm): A = 60 ± 38 (55); B = 40 ± 26 (41); C = 41 ± 33 (34); D = 32 ± 31 (27); E = 6 ± 5 (7); and F = 8 ± 6 (7). Nipple displacements were (mm): A = 84 ± 44 (91); B = 54 ± 24 (56); C = 27 ± 15 (24); and D = 48 ± 20 (48). CONCLUSION: These preliminary results show that preoperative breast MRI in prone position implies a median lesion displacement of about 3-6 cm along the three orthogonal directions in comparison with supine MRI. Conversely, median lesion-to-skin and lesion-to-nipple displacements were less than 1cm, even though nipple displacements were similar to or larger than those of lesions. The lesion-to-nipple distance may be the most reliable measure to be used for second look breast US. Larger studies are warranted in order to define an optimized breast MRI protocol in the preoperative setting.

Breast MRI using a high-relaxivity contrast agent: an overview.

OBJECTIVE: The purpose of this article is to review the use of gadobenate dimeglumine, a high-relaxivity gadolinium-based contrast material, for breast MRI. CONCLUSION: Thanks to its high relaxivity, gadobenate dimeglumine offers valuable advantages in terms of lesion conspicuity, detection rate, and sensitivity for malignant breast lesions. However, a higher enhancement of benign lesions should be taken into account to avoid reduced specificity.

Handling a high relaxivity contrast material for dynamic breast MR imaging using higher thresholds for the initial enhancement.

OBJECTIVES: To increase specificity of gadobenate dimeglumine-enhanced breast magnetic resonance (MR) imaging without losing sensitivity. MATERIALS AND METHODS: IRB approval was obtained for this retrospective study and informed consent was waived. Sixty-eight patients with 73 breast lesions underwent dynamic breast 1.5-T MR imaging with 0.1 mmol/kg of gadobenate dimeglumine and 103 or 111-second temporal resolution. A score system based on shape (round/oval/lobular = 0, linear/dendritic/stellate = 1), margins (defined = 0, undefined = 1), pattern (homogeneous = 0, inhomogeneous = 1, rim = 2), kinetics (continuous = 0, plateau = 1, washout = 2), and initial enhancement was used. Initial enhancement was evaluated with standard (<50% = 0, 50%-100% = 1, >100% = 2) or adjusted (<180% = 0, 180%-240% = 1, >240% = 2) thresholds. Scores 0-2, 3, 4 or 5, and from 6 to 8 were considered as equivalent to Breast Imaging Reporting and Data System 2, 3, 4, and 5, respectively. Pathologic examination (core-, vacuum-assisted, or surgical biopsy) served as a reference standard. Nonparametric tests were used. RESULTS: At histopathology, 52 lesions were malignant, 21 were benign. The initial enhancement for benign lesions was 141% +/- 65% (mean +/- SD), whereas for malignant lesions it was 210% +/- 80% (P = 0.001). The median multifactorial score for benign lesions was 4 using the standard thresholds and 3 using the adjusted thresholds (P < 0.001) whereas for malignant lesions it was 7 and 6, respectively (P < 0.001). Specificity increased from 38% with standard thresholds to 71% with adjusted thresholds (gain of 33%; P = 0.016); positive predictive value 80% and 90%, negative predictive value 100% and 100%, and accuracy 82% and 92%, respectively. Sensitivity was 100% for both thresholds. CONCLUSIONS: Specificity of gadobenate dimeglumine-enhanced breast MR imaging can be increased without limiting its high sensitivity.