Contrast-enhanced ultrasound features as a potential biomarker for the prediction of breast cancer recurrence.

PURPOSE: To investigate the associations between contrast-enhanced ultrasound imaging features and disease recurrence among patients with locally advanced breast cancer treated with neoadjuvant chemotherapy. MATERIALS AND METHODS: In the study, pre- and post-neoadjuvant chemotherapy contrast-enhanced ultrasound images of 43 patients with breast cancer were retrospectively analysed. Post-acquisition image processing involved the placement of freehand-drawn regions of interest, followed by the generation of blood flow kinetics representing blood volume and velocity for these regions of interest. Qualitative and quantitative contrast-enhanced ultrasound parameters were compared to predict recurrence, and receiver operating characteristic analysis was used to evaluate predictive ability. RESULTS: Among the 43 patients, 10 (23%) exhibited disease recurrence (median [range]: 27 [4-68] months). Post-neoadjuvant chemotherapy peak enhancement, wash-in area under the curve, wash-out area under the curve, and wash-in and wash-out area under the curve (p=0.003, p=0.004, p=0.026, and p=0.014, respectively) differed between the no-recurrence and recurrence groups. The area under the receiver operating characteristic curve (0.88; 95% confidence interval: 0.75-1.00) for post-neoadjuvant chemotherapy peak enhancement was the highest among the contrast-enhanced ultrasound parameters, with a cut-off of 13.33 arbitrary units. CONCLUSION: Higher peak enhancement on post-neoadjuvant chemotherapy contrast-enhanced ultrasound images was associated with recurrence in women with locally advanced breast cancer and is a potential biomarker of tumor recurrence.

Morphology and Performance Enhancement through the Strong Passivation Effect of Amphoteric Ions in Tin-based Perovskite Solar Cells.

Despite the optoelectronic similarities between tin and lead halide perovskites, the performance of tin-based perovskite solar cells remains far behind, with the highest reported efficiency to date being ≈14%. This is highly correlated to the instability of tin halide perovskite, as well as the rapid crystallization behavior in perovskite film formation. In this work, l-Asparagine as a zwitterion plays a dual role in controlling the nucleation/crystallization process and improving the morphology of perovskite film. Furthermore, tin perovskites with l-Asparagine show more favorable energy-level matching, enhancing the charge extraction and minimizing the charge recombination, leading to an enhanced power conversion efficiency of 13.31% (from 10.54% without l-Asparagine) with remarkable stability. These results are also in good agreement with the density functional theory calculations. This work not only provides a facile and efficient approach to controlling the crystallization and morphology of perovskite film but also offers guidelines for further improved performance of tin-based perovskite electronic devices.

3D Breast Cancer Segmentation in DCE-MRI Using Deep Learning With Weak Annotation.

BACKGROUND: Deep learning models require large-scale training to perform confidently, but obtaining annotated datasets in medical imaging is challenging. Weak annotation has emerged as a way to save time and effort. PURPOSE: To develop a deep learning model for 3D breast cancer segmentation in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) using weak annotation with reliable performance. STUDY TYPE: Retrospective. POPULATION: Seven hundred and thirty-six women with breast cancer from a single institution, divided into the development (N = 544) and test dataset (N = 192). FIELD STRENGTH/SEQUENCE: 3.0-T, 3D fat-saturated gradient-echo axial T1-weighted flash 3D volumetric interpolated brain examination (VIBE) sequences. ASSESSMENT: Two radiologists performed a weak annotation of the ground truth using bounding boxes. Based on this, the ground truth annotation was completed through autonomic and manual correction. The deep learning model using 3D U-Net transformer (UNETR) was trained with this annotated dataset. The segmentation results of the test set were analyzed by quantitative and qualitative methods, and the regions were divided into whole breast and region of interest (ROI) within the bounding box. STATISTICAL TESTS: As a quantitative method, we used the Dice similarity coefficient to evaluate the segmentation result. The volume correlation with the ground truth was evaluated with the Spearman correlation coefficient. Qualitatively, three readers independently evaluated the visual score in four scales. A P-value <0.05 was considered statistically significant. RESULTS: The deep learning model we developed achieved a median Dice similarity score of 0.75 and 0.89 for the whole breast and ROI, respectively. The volume correlation coefficient with respect to the ground truth volume was 0.82 and 0.86 for the whole breast and ROI, respectively. The mean visual score, as evaluated by three readers, was 3.4. DATA CONCLUSION: The proposed deep learning model with weak annotation may show good performance for 3D segmentations of breast cancer using DCE-MRI. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY: Stage 2.

Ultrafast and Low-Threshold THz Mode Switching of Two-Dimensional Nonlinear Metamaterials.

Judiciously designed two-dimensional THz metamaterials consisting of resonant metallic structures embedded in a dielectric environment locally enhance the electromagnetic field of an incident THz pulse to values sufficiently high to cause nonlinear responses of the environment. In semiconductors, the response is attributed to nonlinear transport phenomena via intervalley scattering, impact ionization, or interband tunneling and can affect the resonant behavior of the metallic structure, which results, for instance, in mode switching. However, details of mode switching, especially time scales, are still debated. By using metallic split-ring resonators with nm-size gaps on intrinsic semiconductors with different bandgaps, we identify the most relevant carrier generation processes. In addition, by combining nonlinear THz time-domain spectroscopy with simulations, we establish the fastest time constant for mode switching to around hundred femtoseconds. Our results not only elucidate dominant carrier generation mechanisms and dynamics but also pave the route toward optically driven modulators with THz bandwidth.

3D-printed THz wave- and phaseplates.

Three-dimensional printing based on fused deposition modeling has been shown to provide a cost-efficient and time-saving tool for fabricating a variety of THz optics for a frequency range of <0.2 THz. By using a broadband THz source, with a useful spectral range from 0.08 THz to 1.5 THz, we show that 3D-printed waveplates operate well up to 0.6 THz and have bandwidths similar to commercial products. Specifically, we investigate quarter- and half-waveplates, q-plates, and spiral phaseplates. We demonstrate a route to achieve broadband performance, so that 3D-printed waveplates can also be used with broadband, few-cycle THz pulses, for instance, in nonlinear THz spectroscopy or other THz high field applications.

Automated breast US as the primary screening test for breast cancer among East Asian women aged 40-49 years: a multicenter prospective study.

OBJECTIVES: To prospectively evaluate the diagnostic performance of screening ABUS as the primary screening test for breast cancer among Korean women aged 40-49 years. METHODS: This prospective, multicenter study included asymptomatic Korean women aged 40-49 years from three academic centers between February 2017 and October 2019. Each participant underwent ABUS without mammography, and the ABUS images were interpreted at each hospital with double-reading by two breast radiologists. Biopsy and at least 1 year of follow-up was considered the reference standard. Diagnostic performance of ABUS screening and subgroup analyses according to patient and tumor characteristics were evaluated. RESULTS: Reference standard data were available for 959 women. The recall rate was 9.8% (95% confidence interval [CI]: 7.9%, 11.7%; 94 of 959 women) and the cancer detection yield was 5.2 per 1000 women (95% CI: -0.6, 11.1; 5 of 959 women). There was only one interval cancer. The sensitivity was 83.3% (95% CI: 53.5%, 100%; 5 of 6 cancers) and the specificity was 90.7% (95% CI: 88.8%, 92.5%; 864 of 95. women). The positive predictive values of biopsies performed (PPV3) was 20.0% (95% CI: 4.3%, 35.7%; 5 of 25 women). Women with heterogeneous background echotexture had a higher recall rate (p = .009) and lower specificity (p = .036). Women with body mass index values < 25 kg/m2 had a higher mean recall rate (p = .046). CONCLUSION: In East Asia, screening automated breast US may be an alternative to screening mammography for detecting breast cancers in women aged 40-49 years. KEY POINTS: • Automated breast US screening for breast cancer in asymptomatic women aged 40-49 is effective with 5.2 per 1000 cancer detection yield. • Women with heterogeneous background echotexture had a higher recall rate and lower specificity. • Women with body mass index < 25 kg/m2 had a higher recall rate.

Risk Stratification of Ductal Carcinoma In Situ and Texture Analysis of Contrast-Enhanced Breast Magnetic Resonance Imaging.

OBJECTIVE: The aim of this study was to investigate whether texture analysis of contrast-enhanced T1 weighted images could predict risk of ductal carcinoma in situ (DCIS). METHODS: The study included 185 DCIS lesions that were classified as either low risk or non-low risk using surgical pathology records. All magnetic resonance imaging texture analyses were performed using postprocessing software, and texture-derived parameters were extracted. RESULTS: The sphericity, compactness, and spherical disproportion were significantly different in the low-risk and non-low risk groups using the Van Nuys Prognostic Index (mean ± SD, 0.479 ± 0.189 vs 0.414 ± 0.176, 0.161 ± 0.159 vs 0.112 ± 0.134, and 2.569 ± 1.434 vs 2.934 ± 1.374, respectively; P < 0.05). In the univariate analyses, sphericity (odds ratio, 7.091; 95% confidence interval, 1.236-40.666; P = 0.028) and compactness (odds ratio, 9.267; 95% confidence interval, 1.125-76.360; P = 0.039) were significantly associated with a high probability of being low risk according to the Van Nuys Prognostic Index. CONCLUSIONS: Whole-lesion texture analysis may be helpful in identifying patients classified as having low-risk DCIS before surgery.

Axillary lymph node dissection is not obligatory in breast cancer patients with biopsy-proven axillary lymph node metastasis.

PURPOSE: The ACOSOG Z0011 trial demonstrated that axillary lymph node dissection (ALND) is unnecessary in select patients with cT1-2N0 tumors undergoing breast-conserving therapy with 1-2 positive sentinel lymph nodes (SLNs). However, patients with preoperatively confirmed ALN metastasis were not included and may be subjected to unnecessary ALND. The aim of this study is to identify patients who can be considered for ALND omission when the preoperative ALN biopsy results are positive. METHODS: Breast cancer patients who underwent preoperative ALN biopsy and primary surgery were retrospectively reviewed. Among patients with positive ALN biopsy results, clinicopathological and imaging characteristics were compared according to LN disease burden (1-2 positive LNs vs. ≥ 3 positive LNs). RESULTS: A total of 542 patients were included in the analysis. Among them, 225 (41.5%) patients had a preoperative positive ALN biopsy. More than 40% of the patients (n = 99, 44.0%) with a positive biopsy had only 1-2 positive ALNs. The association between nodal burden and imaging factors was strongest when ≥ 2 suspicious LNs were identified on PET/CT images (HR 8.795, 95% CI 4.756 to 13.262). More than one imaging modality showing ≥ 2 suspicious LNs was also strongly correlated with ≥ 3 positive ALNs (HR 5.148, 95% CI 2.881 to 9.200). CONCLUSIONS: Nearly half of patients with a preoperative biopsy-proven ALN metastasis had only 1-2 positive LNs on ALND. Patients meeting ACOSOG Z0011 criteria with only one suspicious LN on PET/CT or those presenting with few abnormal ALNs on only one imaging modality appear appropriate for SLNB and consideration of ALND omission.

Electrical control of terahertz frequency conversion from time-varying surfaces.

We investigate the electrical control of frequency conversion from a time-varying interdigitated photo-conductive antenna (IPCA) and time-varying metasurface in the terahertz (THz) frequency range. Ultrafast near-infrared (NIR) optical pulses rapidly modify the conductivities of the IPCA and metasurface; however, external voltages can retard this conductivity transition. Thus, external voltages can be used to control the frequency conversion process based on the interaction between the THz waves and the time-varying surfaces. In the IPCA, both frequency up- and down-conversion processes are suppressed by external voltages. However, in the metasurface, the down-conversion is dramatically suppressed by external voltages, whereas the suppression on the up-conversion is less effective.

Comparison of Positive Predictive Values of Categorization of Suspicious Calcifications Using the 4th and 5th Editions of BI-RADS.

OBJECTIVE. The objective of this study was to evaluate changes in the positive predictive value (PPV) of categorization of suspicious calcification for malignancy with the 4th versus the 5th edition of BI-RADS. MATERIALS AND METHODS. A total of 469 cases from 444 women (mean age, 50.1 years; age range, 23-82 years) with pathologically confirmed suspicious calcifications from January 2012 to June 2016 were enrolled in this retrospective study. Two radiologists determined morphology and distribution by consensus and categorized suspicious calcifications using the categorization systems in the 4th and 5th editions of BI-RADS. The PPVs for morphology, distribution, and categorization of calcifications were analyzed. The Pearson chi-square test was used to compare PPVs for morphology and distribution of suspicious calcification. RESULTS. The PPVs of categorization using the 5th edition matched better with BI-RADS category assessment than did categorization using the 4th edition. The PPVs of morphology were as follows: amorphous, 15.9%; coarse heterogeneous, 31.7%; fine pleomorphic, 58.2%; and fine linear or branching, 90.6% (p < 0.001). The PPVs of distribution were as follows: regional, 31.5%; grouped, 31.3%; linear, 50%; and segmental, 77.9% (p < 0.001). When distribution was divided into two types (grouped or regional vs segmental or linear) and analyzed in combination with suspicious morphology, distribution affected the PPVs and categorization of coarse heterogeneous, fine pleomorphic, and fine linear or branching calcifications. CONCLUSION. Categorization using both morphology and distribution according to the BI-RADS 5th edition was helpful to stratify risk levels of areas of suspicious calcification.

Contrast-Enhanced Ultrasound for Early Prediction of Response of Breast Cancer to Neoadjuvant Chemotherapy.

PURPOSE: To evaluate the time-intensity curve (TIC) parameters on contrast-enhanced ultrasound (CEUS) for early prediction of the response of breast cancer to neoadjuvant chemotherapy (NAC). MATERIALS AND METHODS: This prospective study included 41 patients with breast cancer. CEUS was performed before and after the first cycle of NAC. TIC parameters were analyzed for different regions of interest (ROIs). ROI 1 targeted the hotspot area of greatest enhancement, ROI 2 delineated the area of hyperenhancement, ROI 3 included the entire tumor on grayscale ultrasound, and ROI 4 encircled the normal parenchyma. The TIC perfusion values for ROI 1, 2, and 3 were divided by the ROI 4 value. RESULTS: 11 (26.8 %) of the 41 patients showed a good response (Miller-Payne score 4 or 5) and 30 (73.2 %) showed a minor response (Miller-Payne score 1, 2, or 3). There were significant differences in the wash-out area under the curve, the wash-in and wash-out areas under the curve on ROI 1/4 after the first cycle of NAC, pre-NAC mean transit time local (mTTl) on ROI 2/4, and pre-NAC mTTl on ROI 3/4 between good and minor responders (area under the receiver-operating characteristic curve > 0.70, p < 0.05). CONCLUSION: Some TIC parameters obtained by CEUS may allow prediction of the response of breast cancer to NAC at a very early time point.

The value of pre- and post-neoadjuvant chemotherapy F-18 FDG PET/CT scans in breast cancer: comparison with MRI.

Background Accurate assessment of neoadjuvant chemotherapy (NAC) response with positron emission tomography/computed tomography (PET/CT) or magnetic resonance imaging (MRI) may provide appropriate operation guidelines for individual breast cancer patients. Purpose To compare the values of PET/CT and MRI for response evaluation following NAC in breast cancer patients. Material and Methods Thirty-three consecutive patients who underwent NAC were included. PET/CT and MRI were performed before and one to four weeks after NAC. With response evaluation of PET/CT and MRI, patients with complete/partial responses on imaging studies were considered to be responders, and those showing stable/progressive disease non-responders. Peak standardized uptake value corrected for lean body mass (SULpeak) and metabolic tumor volume (MTV) were measured from PET/CT, and unidimensional diameter (1D) and tumor volume (TV) from MRI. Reduction rates for each parameter were calculated (Δ%SULpeak, Δ%MTV, Δ%1D, and Δ%TV). The pathological response for NAC as reference was evaluated after surgical resection of the remaining tumor in the breast. Results We identified 17 pathological responders and 16 non-responders. PET/CT had lower specificity and accuracy, but higher sensitivity than MRI, although no significant difference was found between PET/CT and MRI. Following NAC, there were significant differences between pathological responders and non-responders in SULpeak ( P < 0.001), MTV ( P < 0.001), 1D ( P = 0.0003), TV ( P = 0.038), Δ%SULpeak ( P = 0.001), Δ%MTV ( P < 0.001), Δ%1D ( P < 0.001), and Δ%TV ( P = 0.001). Conclusion PET/CT showed lower specificity and accuracy than MRI in evaluating responses to NAC, but both PET/CT and MRI parameters may have predictive value in distinguishing therapeutic responders and non-responders following NAC.

Diagnostic Performance of and Breast Tissue Changes at Early Breast MR Imaging Surveillance in Women after Breast Conservation Therapy.

Purpose To investigate the diagnostic performance and tissue changes in early (1 year or less) breast magnetic resonance (MR) imaging surveillance in women who underwent breast conservation therapy for breast cancer. Materials and Methods This prospective study was approved by the institutional review board, and written informed consent was obtained. Between April 2014 and June 2016, 414 women (mean age, 51.5 years; range, 21-81 years) who underwent 422 early surveillance breast MR imaging examinations (median, 6.0 months; range, 2-12 months) after breast conservation therapy were studied. The cancer detection rate, positive predictive value of biopsy, sensitivity, specificity, accuracy, and area under the curve of surveillance MR imaging, mammography, and ultrasonography (US) were assessed. Follow-up was also obtained in 95 women by using positron emission tomography (PET)/computed tomography (CT). Background parenchymal enhancement (BPE) changes in the contralateral breast were assessed according to adjuvant therapy by using the McNemar test. Results Of 11 detected cancers, six were seen at MR imaging only, one was seen at MR imaging and mammography, two were seen at MR imaging and US, one was seen at mammography only, and one was seen at PET/CT only. Three MR imaging-depicted cancers were observed at the original tumor bed, and two MR imaging-depicted cancers were observed adjacent to the original tumor. Among two false-negative MR imaging diagnoses (two cases of ductal carcinoma in situ), one cancer had manifested as calcifications at mammography without differentiated enhancement at MR imaging, and the other cancer was detected at PET/CT, but MR imaging results were negative because of marked BPE, which resulted in focal lesion masking. The positive predictive value of biopsy and the sensitivity, specificity, accuracy, and area under the curve for MR imaging were 32.1% (nine of 28), 81.8% (nine of 11), 95.1% (391 of 411), 94.7% (400 of 422), and 0.88, respectively. The sensitivity of surveillance MR imaging (81.8%; 95% confidence interval [CI]: 48.2%, 97.7%) was higher than that of mammography (18.2%; 95% CI: 2.3%, 51.8%) and US (18.2%; 95% CI: 2.3%, 51.8%), with an overlap in CIs. The BPE showed a significant decrease in the group of patients who received adjuvant chemotherapy (43 BPE decreases and four BPE increases) and the group of patients who received hormone therapy (55 BPE decreases and two BPE increases) (P < .0001 for both). Conclusion Early MR imaging surveillance after breast conservation therapy can be useful in patients who have breast cancer, with superior sensitivity compared with that of mammography and US. The BPE tends to be decreased at short-term follow-up MR imaging in patients who receive adjuvant therapy. © RSNA, 2017.

Intravoxel incoherent motion (IVIM)-derived parameters in diffusion-weighted MRI: Associations with prognostic factors in invasive ductal carcinoma.

PURPOSE: To investigate relationships between intravoxel incoherent motion (IVIM) metrics of invasive ductal carcinoma of the breast and prognostic factors. MATERIALS AND METHODS: This retrospective study included a total of 82 masses from 72 patients who underwent 3T breast magnetic resonance imaging (MRI) and diffusion-weighted imaging. IVIM metrics of tissue diffusivity (Dslow ), pseudodiffusivity (Dfast ), and perfusion fraction (Dpf ) were measured using histogram analysis for whole lesion volumes. We evaluated relationships between IVIM metrics and prognostic factors or subtypes of invasive ductal carcinoma. RESULTS: The Dslow 50th , 75th , and 90th percentile metrics were reduced in the estrogen receptor (ER)-positive group compared with the ER-negative group (individually, P = 0.044, 0.024, 0.045). Additionally, the Dslow 75th percentile value was a significant differentiator of histologic grade, tumor subtype, and Ki-67 grouping (individually, P = 0.024, 0.049, 0.016). The Dpf mean, 75th , 90th percentile, skewness, and kurtosis metrics were correlated with the size of ductal carcinoma in situ (DCIS) component (individually, P = 0.034, 0.032, 0.027, 0.013, 0.013). CONCLUSION: The Dslow metrics differentiated between ER-positive and -negative groups, and the Dpf metrics were associated with the size of the DCIS component. LEVEL OF EVIDENCE: 4 J. MAGN. RESON. IMAGING 2017;45:1394-1406.

Histogram analysis of volume-based apparent diffusion coefficient in breast cancer.

Background Breast cancer is a heterogeneous disease. Recent studies showed that apparent diffusion coefficient (ADC) values have various association with tumor aggressiveness and prognosis. Purpose To evaluate the value of histogram analysis of ADC values obtained from the whole tumor volume in invasive ductal cancer (IDC) and ductal carcinoma in situ (DCIS). Material and Methods This retrospective study included 201 patients with confirmed DCIS (n = 37) and IDC (n = 164). The IDC group was divided into two groups based on the presence of a DCIS component: IDC-DCIS (n = 76) and pure IDC (n = 88). All patients underwent preoperative breast magnetic resonance imaging (MRI) with diffusion-weighted images at 3.0 T. Histogram parameters of cumulative ADC values, skewness, and kurtosis were calculated and statistically analyzed. Results The differences between DCIS, IDC-DCIS, and pure IDC were significant in all percentiles of ADC values, in descending order of DCIS, IDC-DCIS, and pure IDC. IDC showed significantly lower ADC values than DCIS, and ADC50 was the best indicator for discriminating IDC from DCIS, with a threshold of 1.185 × 10-3 mm2/s (sensitivity of 82.9%, specificity of 75.7%). However, multivariate analysis of obtained ADC values showed no significant differences between DCIS, IDC-DCIS, and pure IDC ( P > 0.05). Conclusion Volume-based ADC values showed association with heterogeneity of breast cancer. However, there was no additional diagnostic performance in histogram analysis for differentiating between DCIS, IDC-DCIS, and pure IDC.

Residual microcalcifications after neoadjuvant chemotherapy for locally advanced breast cancer: comparison of the accuracies of mammography and MRI in predicting pathological residual tumor.

BACKGROUND: The aims of this study were to correlate residual mammographic microcalcifications after neoadjuvant chemotherapy (NAC) with pathological results and to compare the accuracy of mammography (MG) and magnetic resonance imaging (MRI) in predicting the size of residual tumors. METHODS: The imaging findings and pathological results for 29 patients with residual microcalcifications after NAC were reviewed. We compared the agreement of the measured extent of residual microcalcifications based on MG and residual enhancement based on MRI with the residual tumor size based on pathology. RESULTS: At final pathology, residual microcalcifications were malignant in 55.2% of cases and benign in 44.8% of cases. In 36% of non-pCR cases, the remaining microcalcifications were benign. Compared with the measurements of residual tumor obtained from pathology, MG showed poor agreement, and MRI showed moderate agreement, for the entire group (concordance correlation coefficient [CCC] = 0.196 vs. 0.566). Regarding the receptor status, the agreement of measurements obtained by MG was superior to that obtained by MRI (CCC = 0.5629, 0.5472 vs. 0.4496, 0.4279) for ER(+) and HER2(-) tumors. In ER(-) tumors, the measurements obtained by MG showed the lowest agreement with the pathological tumor size, which had the highest agreement with those obtained by MRI (CCC = - 0.0162 vs. 0.8584). CONCLUSIONS: Residual mammographic microcalcifications after NAC did not correlate with malignancy in 44.8% of cases. Residual microcalcifications on MG were poorly correlated with pathological tumor size, and MRI might be more reliable for predicting residual tumor size after NAC. Tumor receptor status affected the accuracy of both MG and MRI for predicting residual tumor size after NAC. TRIAL REGISTRATION: CRIS, KCT0002281 ; registered 6 April 2015, retrospectively registered.

Radiation dose affected by mammographic composition and breast size: first application of a radiation dose management system for full-field digital mammography in Korean women.

BACKGROUND: Relative to Western women, Korean women show several differences in breast-related characteristics, including higher rates of dense breasts and small breasts. We investigated how mammographic composition and breast size affect the glandular dose during full-field digital mammography (FFDM) in Korean women using a radiation dose management system. METHODS: From June 1 to June 30, 2015, 2120 FFDM images from 560 patients were acquired and mammographic breast composition and breast size were assessed. We analyzed the correlations of patient age, peak kilovoltage (kVp), current (mAs), compressed breast thickness, compression force, mammographic breast composition, and mammographic breast size with the mean glandular dose (MGD) of the breast using a radiation dose management system. The causes of increased radiation were investigated, among patients with radiation doses above the diagnostic reference level (4th quartile, ≥75%). RESULTS: The MGD per view of 2120 images was 1.81 ± 0.70 mGy. In multivariate linear regression analysis, age was negatively associated with MGD (p < 0.05). The mAs, kVp, compressed breast thickness, and mammographic breast size were positively associated with MGD (p < 0.05). The "dense" group had a significantly higher MGD than the "non-dense" group (p < 0.05). Patients with radiation dose values above the diagnostic reference value had large breasts of dense composition. CONCLUSIONS: Among Korean women, patients with large and dense breasts should be more carefully managed to ensure that a constant radiation dose is maintained.

Highly nonlinear organic crystal OHQ-T for efficient ultra-broadband terahertz wave generation beyond 10 THz.

We report on efficient generation of ultra-broadband terahertz (THz) waves via optical rectification in a novel nonlinear organic crystal with acentric core structure, i.e. 2-(4-hydroxystyryl)-1-methylquinolinium 4-methylbenzenesulfonate (OHQ-T), which possesses an ideal molecular structure leading to a maximized nonlinear optical response for near-infrared-pumped THz wave generation. By systematic studies on wavelength-dependent phase-matching conditions in OHQ-T crystals of different thicknesses we are able to generate coherent THz waves with a high peak-to-peak electric field amplitude of up to 650 kV/cm and an upper cut-off frequency beyond 10 THz. High optical-to-THz conversion efficiency of 0.31% is achieved by efficient index matching with a selective pumping at 1300 nm.

Prospective Study Comparing Two Second-Look Ultrasound Techniques: Handheld Ultrasound and an Automated Breast Volume Scanner.

OBJECTIVES: The aim of this study was to compare the diagnostic performance of handheld ultrasound (US) and an automated breast volume scanner (ABVS) as second-look US techniques subsequent to preoperative breast magnetic resonance imaging (MRI). METHODS: We prospectively enrolled patients with breast cancer who underwent handheld US and ABVS examinations as second-look US modalities for additional suspicious lesions found via preoperative breast MRI. We reviewed each second-look US modality independently and evaluated the detection rate of each modality. We then analyzed the correlation between the detection rate and the MRI factors (size, distance, and enhancement type). RESULTS: From March to September 2014, both types of second-look US examinations were performed on 40 patients with breast cancer who had 76 additional suspicious lesions detected via preoperative breast MRI. The detection rate of the ABVS was higher than that of handheld US for the second-look examination (94.7% versus 86.8%; P< .05). Among the 76 total lesions, 7 were only identified by the ABVS, 1 was only found by handheld US, and 3 were not detected by either the ABVS or handheld US. When we analyzed the correlation between the detection rate and MRI factors, the only meaningful factor was the enhancement type. The ability to detect a nonmass lesion was lower than the ability to detect a mass-type lesion (P < 0.05) for both the ABVS and handheld US. CONCLUSIONS: For a second-look US examination subsequent to preoperative breast MRI in patients with breast cancer, the ABVS is a more efficient modality than handheld US for preoperative evaluations. However, both techniques have limitations in detecting nonmass lesions.

Extramammary findings on breast MRI: prevalence and imaging characteristics favoring malignancy detection: a retrospective analysis.

BACKGROUND: Little study of the extramammary finding of breast MRIs has been done with only descriptive work of the prevalence of location and malignancy. The purpose of the present study was to assess the prevalence, the location, and the imaging characteristics of the incidentally detected extramammary findings on breast MRI and to determine potential malignant characteristics. METHODS: The study evaluated extramammary findings in 109 patients who underwent breast MRI for the staging of breast cancer and for the follow-up of post-therapy. Prevalence, the location, clinicopathologic findings of breast cancer size, metastasis, and MRI characteristics were evaluated retrospectively. Malignancy of extramammary findings was determined based on the pathologic examinations and diagnostic images. RESULTS: One hundred forty-nine incidental findings were detected in 109 (4.6%) of 2361 patients, and 69 cases were confirmed or considered to be malignant. The most common site was the bone (43/149, 28.9%) with malignancy found in 30 (69.8%) of 43 bone lesions. Less frequent tumor locations were the liver (22.1%), lung (21.5%), pleura or chest wall (10.1%), mediastinum (6.7%), supraclavicular lymph nodes (LNs) (6.0%), and others (4.7%). Findings of significant relevance with malignancy of the extramammary findings included bigger size of breast cancer, presence of LN metastasis, and distant metastasis (P < 0.01). Lesions showing iso- or hypo signal intensity (SI) on T2-weighted imaging (T2WI) (P = 0.000), contrast enhancement (P = 0.000), high SI on diffusion-weighted imaging (DWI) (P = 0.049), low SI on apparent-diffusion-coefficient map relative to DWI (P = 0.000), and multiplicity (P = 0.000) of the extramammary finding were significantly related to malignancy. CONCLUSIONS: Extramammary findings on breast MRI are not rare. Clinicopathologic features of the breast cancer and MRI features of extramammary findings could be useful in estimating the malignancy of the incidental extramammary finding.