Changes in kinetic heterogeneity of breast cancer via computer-aided diagnosis on MRI predict the pathological response to neoadjuvant systemic therapy.

OBJECTIVE: To evaluate whether the computer-aided diagnosis (CAD)-extracted kinetic heterogeneity of breast cancer on MRI and changes therein during treatment were associated with the pathological response to neoadjuvant systemic therapy (NST). MATERIALS AND METHODS: Consecutive patients with invasive breast cancer, who underwent NST followed by surgery between 2014 and 2020, were retrospectively evaluated. Using a commercial CAD system, kinetic features (angiovolume, peak enhancement, delayed enhancement profiles, and kinetic heterogeneity) of breast cancer were assessed with pre- and mid-treatment MRI. Multivariate logistic regression was used to identify the associations between CAD-extracted kinetic features and pathological complete response (pCR). RESULTS: A total of 130 patients (mean age, 55 years) were included, 37 (28.5%) of whom achieved a pCR. When the pre- and mid-treatment MRI data were compared, the pCR group exhibited greater changes in kinetic heterogeneity (86.14 ± 32.05% vs. 8.50 ± 141.01%, p < 0.001) and angiovolume (95.20 ± 14.29% vs. 19.89 ± 320.16%; p < 0.001) than the non-pCR group. Multivariate regression analysis showed that a large change in kinetic heterogeneity (odds ratio (OR) = 1.030, p < 0.001), age (OR = 0.931, p = 0.005), progesterone receptor negativity (OR = 7.831, p = 0.001), and HER2 positivity (OR = 3.455, p = 0.017) were associated with pCR. CONCLUSIONS: A greater change in the CAD-extracted kinetic heterogeneity of breast cancer between pre- and mid-treatment MRI was associated with a pCR in patients on NST. KEY POINTS: A greater change in kinetic heterogeneity was associated with a pathological complete response. Computer-aided diagnosis-extracted kinetic heterogeneity might serve as a quantitative biomarker of therapeutic efficacy.

Non-ECG-gated high-pitch CT angiography versus hybrid ECG-gated CT angiography for aorta using 512-slice CT: comparison of image quality and radiation dose.

BACKGROUND: There have been few reports comparing image quality and radiation dose of aorta computed tomography angiography (CTA) between the high-pitch and the hybrid technique. PURPOSE: To compare the image quality and radiation dose among non-electrocardiogram (ECG)-gated high-pitch CTA and hybrid ECG-gated CTA of the aorta using 512-slice CT. MATERIAL AND METHODS: This retrospective study included 110 patients who underwent non-ECG-gated high-pitch CTA (group 1) or hybrid ECG-gated CTA (group 2) of the entire aorta. Interpretability, image noise, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and the mean effective radiation dose were compared. RESULTS: The mean image noise of the whole aorta was significantly lower (15.7 ± 1.8 HU vs. 16.5 ± 1.2 HU, P = 0.008) in group 1 than in group 2. The CNR (22.3 ± 4.7 vs. 20.0 ± 3.9, P < 0.001) and SNR (26.5 ± 4.9 vs. 23.2 ± 4.0, P < 0.001) were higher in group 2 compared with group 1. Neither group showed a significant difference in interpretability of the ascending aorta, cardiac chamber, aortic valve, right ostium, and left ostium (all P = 1). The mean effective radiation dose was significantly lower in group 1 than in group 2 (3.5 ± 0.9 mSv vs. 4.3 ± 0.8 mSv, P < 0.001). CONCLUSION: The non-ECG-gated high-pitch technique shows significantly improved CNR and SNR due to reduced noise with lower radiation exposure. The interpretability of the cardiac structure, ascending aorta, aortic valve, and both ostia did not differ significantly between the two groups.

Comparison of Fused Diffusion-Weighted Imaging Using Unenhanced MRI and Abbreviated Post-Contrast-Enhanced MRI in Patients with Breast Cancer.

Background and Objectives: To determine the percentage of breast cancers detectable by fused diffusion-weighted imaging (DWI) using unenhanced magnetic resonance imaging (MRI) and abbreviated post-contrast-enhanced MRI. Materials and Methods: Between October 2016 and October 2017, 194 consecutive women (mean age, 54.2 years; age range, 28-82 years) with newly diagnosed unilateral breast cancer, who underwent preoperative 3.0 T breast MRI with DWI, were evaluated. Both fused DWI and abbreviated MRI were independently reviewed by two radiologists for the detection of index cancer (which showed the most suspicious findings in both breasts), location, lesion conspicuity, lesion type, and lesion size. Moreover, the relationship between cancer detection and histopathological results of surgical specimens was evaluated. Results: Index cancer detection rates were comparable between fused DWI and abbreviated MRI (radiologist 1: 174/194 [89.7%] vs. 184/194 [94.8%], respectively, p = 0.057; radiologist 2: 174/194 [89.7%] vs. 183/194 [94.3%], respectively, p = 0.092). In both radiologists, abbreviated MRI showed a significantly higher lesion conspicuity than fused DWI (radiologist 1: 9.37 ± 2.24 vs. 8.78 ± 3.03, respectively, p < 0.001; radiologist 2: 9.16 ± 2.32 vs. 8.39 ± 2.93, respectively, p < 0.001). The κ value for the interobserver agreement of index cancer detection was 0.67 on fused DWI and 0.85 on abbreviated MRI. For lesion conspicuity, the intraclass correlation coefficients were 0.72 on fused DWI and 0.82 on abbreviated MRI. Among the histopathological factors, tumor invasiveness was associated with cancer detection on both fused DWI (p = 0.011) and abbreviated MRI (p = 0.004, radiologist 1), lymphovascular invasion on abbreviated MRI (p = 0.032, radiologist 1), and necrosis on fused DWI (p = 0.031, radiologist 2). Conclusions: Index cancer detection was comparable between fused DWI and abbreviated MRI, although abbreviated MRI showed a significantly better lesion conspicuity.

Diffusion Kurtosis MR Imaging of Invasive Breast Cancer: Correlations With Prognostic Factors and Molecular Subtypes.

BACKGROUND: The associations between diffusion kurtosis imaging (DKI)-derived parameters and clinical prognostic factors of breast cancer have not been fully evaluated; this knowledge may have implications for outcome prediction and treatment strategies. PURPOSE: To determine associations between quantitative diffusion parameters derived from DKI and diffusion-weighted imaging (DWI) and the prognostic factors and molecular subtypes of breast cancer. STUDY TYPE: Retrospective. POPULATION: A total of 383 women (mean age, 53.8 years; range, 31-82 years) with breast cancer who underwent preoperative breast MRI including DKI and DWI. FIELD STRENGTH/SEQUENCE: A 3.0 T; DKI using a spin-echo echo-planar imaging (EPI) sequence (b values: 200, 500, 1000, 1500, and 2000 sec/mm2 ), DWI using a readout-segmented EPI sequence (b values: 0 and 1000 sec/mm2 ) and dynamic contrast-enhanced breast MRI. ASSESSMENT: Two radiologists (J.Y.K. and H.S.K. with 9 years and 1 year of experience in MRI, respectively) independently measured kurtosis, diffusivity, and apparent diffusion coefficient (ADC) values of breast cancer by manually placing a regions of interest within the lesion. Diffusion measures were compared according to nodal status, grade, and molecular subtypes. STATISTICAL TESTS: Kruskal-Wallis test, Mann-Whitney U test with Bonferroni correction, receiver operating characteristic (ROC) analysis, and multivariate logistic regression analysis. (Statistical significance level of P < 0.05). RESULTS: All diffusion measures showed significant differences according to axillary nodal status and histological grade. Kurtosis showed significant differences among molecular subtypes. The luminal subtype (median 1.163) showed a higher kurtosis value compared to the HER2-positive (median 0.962) or triple-negative subtypes (median 1.072). ROC analysis for differentiating HER2-positive from luminal subtypes revealed that kurtosis yielded the highest area under the curve of 0.781. In multivariate analyses, kurtosis remained a significant factor associated with differentiation between HER2-positive and luminal (odds ratio [OR] = 0.993), triple-negative and luminal (OR = 0.995), and HER2-positive and triple-negative subtypes (OR = 0.994). DATA CONCLUSION: Quantitative diffusion parameters derived from DKI and DWI are associated with prognostic factors for breast cancer. Moreover, DKI-derived kurtosis can help distinguish between the molecular subtypes of breast cancer. EVIDENCE LEVEL: 4 TECHNICAL EFFICACY: 3.

Characterization of breast cancer subtypes based on quantitative assessment of intratumoral heterogeneity using dynamic contrast-enhanced and diffusion-weighted magnetic resonance imaging.

OBJECTIVE: To investigate whether intratumoral heterogeneity, assessed via dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion-weighted imaging (DWI), reflects the molecular subtypes of invasive breast cancers. MATERIAL AND METHODS: We retrospectively evaluated data from 248 consecutive women (mean age ± standard deviation, 54.6 ± 12.2 years) with invasive breast cancer who underwent preoperative DCE-MRI and DWI between 2019 and 2020. To evaluate intratumoral heterogeneity, kinetic heterogeneity (a measure of heterogeneity in the proportions of tumor pixels with delayed washout, plateau, and persistent components within a tumor) was assessed with DCE-MRI using a commercially available computer-aided diagnosis system. Apparent diffusion coefficients (ADCs) were obtained using a region-of-interest technique, and ADC heterogeneity was calculated using the following formula: (ADCmax-ADCmin)/ADCmean. Possible associations between imaging-based heterogeneity values and breast cancer subtypes were analyzed. RESULTS: Of the 248 invasive breast cancers, 61 (24.6%) were classified as luminal A, 130 (52.4%) as luminal B, 25 (10.1%) as HER2-enriched, and 32 (12.9%) as triple-negative breast cancer (TNBC). There were significant differences in the kinetic and ADC heterogeneity values among tumor subtypes (p < 0.001 and p = 0.023, respectively). The TNBC showed higher kinetic and ADC heterogeneity values, whereas the HER2-enriched subtype showed higher kinetic heterogeneity values compared to the luminal subtypes. Multivariate linear analysis showed that the HER2-enriched (p < 0.001) and TNBC subtypes (p < 0.001) were significantly associated with higher kinetic heterogeneity values. The TNBC subtype (p = 0.042) was also significantly associated with higher ADC heterogeneity values. CONCLUSIONS: Quantitative assessments of heterogeneity in enhancement kinetics and ADC values may provide biological clues regarding the molecular subtypes of breast cancer. KEY POINTS: • Higher kinetic heterogeneity was associated with HER2-enriched and triple-negative breast cancer. • Higher ADC heterogeneity was associated with triple-negative breast cancer. • Aggressive breast cancer subtypes exhibited higher intratumoral heterogeneity based on MRI.

Fusion of high b-value diffusion-weighted and unenhanced T1-weighted images to diagnose invasive breast cancer: factors associated with false-negative results.

OBJECTIVES: We sought factors associated with false-negative results in the diagnosis of invasive breast cancer via non-contrast breast magnetic resonance imaging (MRI) using fused high b-value diffusion-weighted imaging (DWI) and unenhanced T1-weighted images (T1WI). METHODS: Between 2018 and 2019, 316 consecutive women (mean age, 54.6 years) with invasive breast cancer who underwent preoperative breast MRI, including fused high b-value DWI and unenhanced T1WI, were retrospectively evaluated. Malignancy confidence ratings of the most suspicious breast lesions evident on fused DWI were derived by two radiologists using a 6-point Likert-type scale. Both clinicopathological and imaging features were analyzed. Multivariate regression analysis was performed to identify factors associated with false-negative DWI results in the diagnosis of invasive breast cancer. RESULTS: Of the 316 breast cancers, fused DWI yielded 289 (91.5%) true-positive and 27 (8.5%) false-negative results. Multivariate analysis showed that small tumor size (≤ 1 cm) (odds ratio [OR], 5.95; 95% confidence interval [CI], 2.11, 16.81; p = 0.001), presence of calcifications in the tumor (OR, 3.41; 95% CI, 1.27, 9.15; p = 0.015), and a moderate/marked background diffusion signal (ORs, 4.23 and 19.18; 95% CI, 1.31, 13.67 and 6.51, 56.46; p = 0.016 and p < 0.001, respectively) were significantly associated with false-negative results. In subgroup analysis of 141 screening-detected cancers, a marked background diffusion signal (OR, 7.94; 95% CI, 2.30, 27.35; p = 0.001) remained significantly associated with false-negative results in the multivariate analysis. CONCLUSIONS: In addition to histopathological features, a higher background diffusion signal was associated with false-negative results in the diagnosis of invasive breast cancer via non-contrast MRI using fused high b-value DWI and unenhanced T1WI. KEY POINTS: • Subcentimeter tumors and presence of calcifications in the tumor are associated with false-negative diffusion-weighted imaging results in the diagnosis of invasive breast cancer. • A higher degree of background diffusion signal may lead to false-negative interpretation of diffusion-weighted imaging in patients with invasive breast cancer.

Ultrafast Dynamic Contrast-Enhanced MRI Using Compressed Sensing: Associations of Early Kinetic Parameters With Prognostic Factors of Breast Cancer.

OBJECTIVE. The purpose of this study was to investigate whether early kinetic parameters derived from ultrafast dynamic contrast-enhanced MRI (DCE-MRI) using compressed sensing are associated with prognostic factors for breast cancer. MATERIALS AND METHODS. We evaluated 201 consecutive women (mean age, 54.6 years) with breast cancer (168 invasive, 33 ductal carcinoma in situ) who underwent both ultrafast DCE-MRI using compressed sensing (temporal resolution, 4.7 seconds; spatial resolution, 0.8 × 1.1 × 0.9 mm) and surgery between 2018 and 2019. Early kinetic parameters (time to enhancement [TTE] and maximum slope [MS]) were measured in breast lesions by two radiologists using a software program and were correlated with histopathologic prognostic factors. The Mann-Whitney U test and linear regression analysis were used. RESULTS. The median TTE and MS values for breast cancer were 11.9 seconds and 7.7%/s, respectively. The median MS was significantly larger in invasive cancer lesions than in ductal carcinoma in situ lesions (8.4%/s vs 4.7%/s, p < .001). In women with invasive cancer, multivariate linear regression analyses showed that a larger tumor size (> 2 cm) (p = .048) and estrogen receptor-negative status (p < .001) were significantly associated with a shorter TTE. A higher histologic grade (grade 3) (p = .01) was significantly associated with a larger MS. We observed excellent interobserver agreement between two readers in the measurements of TTE and MS (intraclass correlation coefficients, 0.943 and 0.890, respectively). CONCLUSION. Ultrafast MRI-derived early enhancement parameters, such as TTE and MS, are associated with histopathologic prognostic factors in women with breast cancer.

Kinetic Heterogeneity of Breast Cancer Determined Using Computer-aided Diagnosis of Preoperative MRI Scans: Relationship to Distant Metastasis-Free Survival.

Background Higher peak enhancement and washout component values measured on preoperative breast MRI scans with computer-aided diagnosis (CAD) are presumed to be associated with worse recurrence-free survival. Purpose To investigate whether CAD-extracted kinetic features of breast cancer and the heterogeneity of these features at preoperative MRI are associated with distant metastasis-free survival in women with invasive breast cancer. Materials and Methods Consecutive women with newly diagnosed invasive breast cancer who underwent preoperative MRI were retrospectively evaluated between 2011 and 2012. A commercially available CAD system was used to extract the peak enhancement and delayed enhancement profiles of each breast cancer case from preoperative MRI data. The kinetic heterogeneity of these features (a measure of heterogeneity in the proportions of tumor pixels with delayed washout, plateau, and persistent components within a tumor) was calculated to evaluate intratumoral heterogeneity. Cox proportional hazards models were used to investigate the associations between CAD-extracted kinetic features and distant metastasis-free survival after adjusting for clinical-pathologic factors. Results A total of 276 consecutive women (mean age, 53 years) were evaluated. In 28 of 276 (10.1%) women, distant metastasis developed at a median follow-up of 79 months. A higher degree of kinetic heterogeneity was observed in women with distant metastases than in those without distant metastases (mean, 0.70 ± 0.2 vs 0.43 ± 0.3; P < .001). Multivariable Cox proportional hazards analysis revealed that a higher degree of kinetic heterogeneity (hazard ratio [HR], 19.2; 95% confidence interval [CI]: 4.2, 87.1; P < .001), higher peak enhancement (HR, 1.001; 95% CI: 1.000, 1.002; P = .045), the presence of lymphovascular invasion (HR, 3.3; 95% CI: 1.5, 7.5; P = .004), and a higher histologic grade (ie, grade 3) (HR, 2.2; 95% CI: 1.0, 4.9; P = .044) were associated with worse distant metastasis-free survival. Conclusion Higher values of kinetic heterogeneity and peak enhancement as determined with computer-aided diagnosis of preoperative MRI were associated with worse distant metastasis-free survival in women with invasive breast cancer. © RSNA, 2020 See also the editorial by El Khouli and Jacobs in this issue.

Diffusion-weighted MRI of estrogen receptor-positive, HER2-negative, node-negative breast cancer: association between intratumoral heterogeneity and recurrence risk.

OBJECTIVES: To investigate possible associations between quantitative apparent diffusion coefficient (ADC) metrics derived from whole-lesion histogram analysis and breast cancer recurrence risk in women with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative, node-negative breast cancer who underwent the Oncotype DX assay. METHODS: This retrospective study was conducted on 105 women (median age, 48 years) with ER-positive, HER2-negative, node-negative breast cancer who underwent the Oncotype DX test and preoperative diffusion-weighted imaging (DWI). Histogram analysis of pixel-based ADC data of whole tumors was performed, and various ADC histogram parameters (mean, 5th, 25th, 50th, 75th, and 95th percentiles of ADCs) were extracted. The ADC difference value (defined as the difference between the 5th and 95th percentiles of ADCs) was calculated to assess intratumoral heterogeneity. Associations between quantitative ADC metrics and the recurrence risk, stratified using the Oncotype DX recurrence score (RS), were evaluated. RESULTS: Whole-lesion histogram analysis showed that the ADC difference value was different between the low-risk recurrence (RS < 18) and the non-low-risk recurrence (RS ≥ 18; intermediate to high risk of recurrence) groups (0.600 × 10-3 mm2/s vs. 0.746 × 10-3 mm2/s, p < 0.001). Multivariate regression analysis demonstrated that a lower ADC difference value (< 0.559 × 10-3 mm2/s; odds ratio [OR] = 5.998; p = 0.007) and a small tumor size (≤ 2 cm; OR = 3.866; p = 0.012) were associated with a low risk of recurrence after adjusting for clinicopathological factors. CONCLUSIONS: The ADC difference value derived from whole-lesion histogram analysis might serve as a quantitative DWI biomarker of the recurrence risk in women with ER-positive, HER2-negative, node-negative invasive breast cancer. KEY POINTS: • A lower ADC difference value and a small tumor size were associated with a low risk of recurrence of breast cancer. • The ADC difference value could be a quantitative marker for intratumoral heterogeneity. • Whole-lesion histogram analysis of the ADC could be helpful for discriminating the low-risk from non-low-risk recurrence groups.

Diffusion-weighted Imaging of Invasive Breast Cancer: Relationship to Distant Metastasis-free Survival.

Background Combined minimum apparent diffusion coefficient (ADC) and ADC difference value may improve the diagnostic performance of breast diffusion-weighted imaging (DWI) compared with mean ADC. Purpose To investigate whether ADC parameters at DWI are associated with distant metastasis-free survival in women with invasive breast cancer. Materials and Methods Between 2013 and 2014, 258 consecutive women (mean age ± standard deviation, 50.9 years ± 10.5; age range, 23-85 years) with newly diagnosed invasive breast cancer who underwent preoperative MRI with DWI were evaluated. All DWI examinations were retrospectively reviewed by two radiologists blinded to clinical information. The mean, minimum, and maximum ADCs were measured by manually placing regions of interest within the lesions, and the ADC difference value (the difference between minimum and maximum ADCs) was calculated to evaluate intratumoral heterogeneity. Cox proportional hazards models were used to determine the associations between ADC parameters and distant metastasis-free survival after adjustment for clinical-pathologic factors. Results In 25 of the 258 women (9.7%), distant metastasis developed at a median follow-up of 51 months. The ADC difference value was higher in women with distant metastasis than in those without distant metastasis (mean, 0.743 × 10-3 mm2/sec vs 0.566 × 10-3 mm2/sec, respectively; P < .001). Multivariable Cox proportional hazards analysis showed that a higher ADC difference value (>0.698 × 10-3 mm2/sec) (hazard ratio [HR], 4.5; 95% confidence interval [CI]: 2.0, 10.0; P < .001), presence of axillary node metastasis (HR, 3.3; 95% CI: 1.2, 9.3; P = .02), and estrogen receptor negativity (HR, 2.6; 95% CI: 1.2, 5.7; P = .02) were associated with poorer distant metastasis-free survival. Conclusion A higher apparent diffusion coefficient difference value at diffusion-weighted imaging is associated with poorer distant metastasis-free survival of women with invasive breast cancer. © RSNA, 2019 See also the editorial by Taourel in this issue.

Apparent diffusion coefficient cannot predict molecular subtype and lymph node metastases in invasive breast cancer: a multicenter analysis.

BACKGROUND: Radiological imaging plays a central role in the diagnosis of breast cancer (BC). Some studies suggest MRI techniques like diffusion weighted imaging (DWI) may provide further prognostic value by discriminating between tumors with different biologic characteristics including receptor status and molecular subtype. However, there is much contradictory reported data regarding such associations in the literature. The purpose of the present study was to provide evident data regarding relationships between quantitative apparent diffusion coefficient (ADC) values on DWI and pathologic prognostic factors in BC. METHODS: Data from 5 centers (661 female patients, mean age, 51.4 ± 10.5 years) were acquired. Invasive ductal carcinoma (IDC) was diagnosed in 625 patients (94.6%) and invasive lobular carcinoma in 36 cases (5.4%). Luminal A carcinomas were diagnosed in 177 patients (28.0%), luminal B carcinomas in 279 patients (44.1%), HER 2+ carcinomas in 66 cases (10.4%), and triple negative carcinomas in 111 patients (17.5%). The identified lesions were staged as T1 in 51.3%, T2 in 43.0%, T3 in 4.2%, and as T4 in 1.5% of the cases. N0 was found in 61.3%, N1 in 33.1%, N2 in 2.9%, and N3 in 2.7%. ADC values between different groups were compared using the Mann-Whitney U test and by the Kruskal-Wallis H test. The association between ADC and Ki 67 values was calculated by Spearman's rank correlation coefficient. RESULTS: ADC values of different tumor subtypes overlapped significantly. Luminal B carcinomas had statistically significant lower ADC values compared with luminal A (p = 0.003) and HER 2+ (p = 0.007) lesions. No significant differences of ADC values were observed between luminal A, HER 2+ and triple negative tumors. There were no statistically significant differences of ADC values between different T or N stages of the tumors. Weak statistically significant correlation between ADC and Ki 67 was observed in luminal B carcinoma (r = - 0.130, p = 0.03). In luminal A, HER 2+ and triple negative tumors there were no significant correlations between ADC and Ki 67. CONCLUSION: ADC was not able to discriminate molecular subtypes of BC, and cannot be used as a surrogate marker for disease stage or proliferation activity.

Risk stratification of ductal carcinoma in situ using whole-lesion histogram analysis of the apparent diffusion coefficient.

OBJECTIVES: To investigate the value of the whole-lesion histogram apparent diffusion coefficient (ADC) metrics for differentiating low-risk from non-low-risk ductal carcinoma in situ (DCIS). METHODS: The authors identified 93 women with pure DCIS who had undergone preoperative MR imaging and diffusion-weighted imaging from 2013 to 2016. Histogram analysis of pixel-based ADC data of the whole tumour volume was performed by two radiologists using a software tool. The results were compared between low-risk and non-low-risk DCIS. Associations between quantitative ADC metrics and low-risk DCIS were evaluated by receiver operating characteristics (ROC) curve and logistic regression analyses. RESULTS: In whole-lesion histogram analysis, mean ADC and 5th, 50th and 95th percentiles of ADC were significantly different between low-risk and non-low-risk DCIS (1.522, 1.207, 1.536 and 1.854 × 10-3 mm2/s versus 1.270, 0.917, 1.261 and 1.657 × 10-3 mm2/s, respectively; p = .004, p = .003, p = .004 and p = .024, respectively). ROC curve analysis for differentiating low-risk DCIS revealed that 5th percentile ADC yielded the largest area under the curve (0.786) among the metrics of whole-lesion histogram, and the optimal cut-off point was 1.078 × 10-3 mm2/s (sensitivity 80%, specificity 75.9%, p = .001). Multivariate regression analysis revealed that a high 5th percentile of ADC (> 1.078× 10-3 mm2/s; odds ratio [OR] = 10.494, p = .016), small tumour size (≤ 2 cm; OR = 12.692, p = .008) and low Ki-67 status (< 14%; OR = 10.879, p = .046) were significantly associated with low-risk DCIS. CONCLUSIONS: Assessment with whole-lesion histogram analysis of the ADC could be helpful for identifying patients with low-risk DCIS. KEY POINTS: • Whole-lesion histogram ADC metrics could be helpful for differentiating low-risk from non-low-risk DCIS. • A high 5th percentile ADC was a significant factor associated with low-risk DCIS. • Risk stratification of DCIS is important for their management.

Low-Dose CT With the Adaptive Statistical Iterative Reconstruction V Technique in Abdominal Organ Injury: Comparison With Routine-Dose CT With Filtered Back Projection.

OBJECTIVE. The purpose of this study was to evaluate and compare the diagnostic performance and image quality of low-dose CT performed with adaptive statistical iterative reconstruction (ASIR)-V with those of routine-dose CT with filtered back projection (FBP) in the evaluation of abdominal organ injury. MATERIALS AND METHODS. The study enrolled 197 patients with trauma who underwent multiphase abdominal CT, including routine-dose portal venous phase imaging with FBP and low-dose delayed phase imaging with 50% ASIR-V. The presence of abdominal organ injuries (liver, spleen, pancreas, kidney) was reviewed, and injuries were graded according to American Association for the Surgery of Trauma (AAST) scales. CT detection rates of organ injury and AAST grading with the two protocols were compared by McNemar test. Subjective analysis of image noise and artifacts and objective analysis of CT noise were performed by unpaired t test. RESULTS. Compared with the routine-dose protocol, the low-dose protocol enabled an mean dose reduction of 59.8%. The detection rates and diagnostic performance of AAST grading did not differ significantly between the two protocols (detection rate, p = 0.289; diagnostic performance, p > 0.999). Objective image noise was significantly less with the low-dose protocol than with the routine-dose protocol (p < 0.001). Subjective imaging artifacts were similar between the low-dose and routine-dose protocols (p = 0.539). CONCLUSION. Compared with routine-dose protocol with FBP, low-dose CT with ASIR-V was useful for assessing multiorgan abdominal injury without impairing image quality.

Can diffusion-weighted imaging predict tumor grade and expression of Ki-67 in breast cancer? A multicenter analysis.

BACKGROUND: Numerous studies have analyzed associations between apparent diffusion coefficient (ADC) and histopathological features such as Ki-67 proliferation index in breast cancer (BC), with mixed results. The purpose of this study was to perform a multicenter analysis to determine relationships between ADC and expression of Ki-67 and tumor grade in BC. METHODS: For this study, data from six centers were acquired. The sample comprises 870 patients (all female; mean age, 52.6 ± 10.8 years). In every case, breast magnetic resonance imaging with diffusion-weighted imaging was performed. The comparison of ADC values in groups was performed by Mann-Whitney U test where the p values are adjusted for multiple testing (Bonferroni correction). The association between ADC and Ki-67 values was calculated by Spearman's rank correlation coefficient. Sensitivity, specificity, negative and positive predictive values, accuracy, and AUC were calculated for the diagnostic procedures. ADC thresholds were chosen to maximize the Youden index. RESULTS: Overall, data of 870 patients were acquired for this study. The mean ADC value of the tumors was 0.98 ± 0.22 × 10- 3 mm2 s- 1. ROC analysis showed that it is impossible to differentiate high/moderate grade tumors from grade 1 lesions using ADC values. Youden index identified a threshold ADC value of 1.03 with a sensitivity of 56.2% and specificity of 67.9%. The positive predictive value was 18.2%, and the negative predictive value was 92.4%. The level of the Ki-67 proliferation index was available for 845 patients. The mean value was 12.33 ± 21.77%. ADC correlated with weak statistical significant with expression of Ki-67 (p = - 0.202, p < 0.001). ROC analysis was performed to distinguish tumors with high proliferative potential from tumors with low expression of Ki-67 using ADC values. Youden index identified a threshold ADC value of 0.91 (sensitivity 64%, specificity 50%, positive predictive value 67.7%, negative predictive value 45.0%). CONCLUSIONS: ADC cannot be used as a surrogate marker for proliferation activity and/or for tumor grade in breast cancer.

Diffusion tensor magnetic resonance imaging of breast cancer: associations between diffusion metrics and histological prognostic factors.

OBJECTIVES: To investigate whether quantitative diffusion metrics derived from diffusion tensor imaging (DTI) are associated with histological prognostic factors in breast cancer patients. METHODS: This retrospective study was approved by the institutional review board, and informed consent was waived. Between 2016 and 2017, 251 consecutive women (mean age, 53.8 years) with breast cancer (230 invasive, 21 in situ) who underwent preoperative magnetic resonance (MR) imaging with DTI were identified. Diffusion gradients were applied in 20 directions (b values, 0 and 1,000 s/mm2). DTI metrics - mean diffusivity (MD) and fractional anisotropy (FA) - were measured for breast lesions and contralateral normal breast by two radiologists and were correlated with histological findings using the Mann-Whitney U-test and linear regression analysis. RESULTS: MD and FA were significantly lower for breast cancers than for normal fibroglandular tissues (1.03 ± 0.25×10-3 mm2/s vs. 1.60 ± 0.19×10-3 mm2/s, p < 0.001 and 0.29 ± 0.09 vs. 0.33 ± 0.06, p < 0.001, respectively). Significant differences were observed in MD between invasive cancer and ductal carcinoma in situ lesions (p < 0.001). Multivariate linear analysis showed that larger size (>2 cm) (p = 0.007), high histological grade (grade 3) (p = 0.045) and axillary node metastasis (p = 0.009) were significantly associated with lower MD in invasive breast cancer patients. Larger size (p < 0.001) and high histological grade (p = 0.025) were significantly associated with lower FA. CONCLUSIONS: DTI-derived diffusion metrics, such as MD and FA, are associated with histological prognostic factors in breast cancer patients. KEY POINTS: • MD was significantly lower for breast cancers than for normal breast tissues. • FA was significantly lower for breast cancers than for normal breast tissues. • Reduced DTI metrics were associated with poor prognostic factors of breast cancer. • DTI may provide valuable information concerning biological aggressiveness in breast cancer.

Image quality and radiation dose of CT venography with double dose reduction using model based iterative reconstruction: comparison with conventional CT venography using filtered back projection.

Background Computed tomography venography (CTV) at low kVp using model-based iterative reconstruction (MBIR) can enhance vascular enhancement with noise reduction. Purpose To evaluate image qualities and radiation doses of CTV at 80 kVp using MBIR and a small iodine contrast media (CM) dose and to compare these with those of CTV performed using a conventional protocol. Material and Methods Sixty-five patients (mean age = 58.1 ± 7.2 years) that underwent CTV for the evaluation of deep vein thrombosis (DVT) and varicose veins were enrolled in this study. Patients were divided into two groups: Group A (35 patients, 80 kVp, MBIR, automatic tube current modulation, CM = 270 mg/mL, 100 mL) and Group B (30 patients, 100 kVp, filtered back projection [FBP], 120 fixed mA, CM = 370 mg/mL, 120 mL). Objective and subjective image qualities of inferior vena cava (IVC), femoral vein (FV), and popliteal vein (PV) were assessed and radiation doses were recorded. Results Mean vascular enhancement in group A was significantly lower than in group B ( P < 0.01). Noise in group A was significantly lower than in group B except for PV and contrast-to-noise ratio were not significantly different in the two groups ( P > 0.05). In addition, radiation dose in group A was significantly lower than in group B ( P < 0.001). Subjective image quality comparison revealed group A was statistically inferior to group B except for subjective image noise. Conclusion CTV at 80 kVp using MBIR with small iodine contrast dose provided acceptable image quality at a lower radiation dose than conventional CTV using FBP.

Patterns of malignant non-mass enhancement on 3-T breast MRI help predict invasiveness: using the BI-RADS lexicon fifth edition.

Background Non-mass enhancements (NME) with invasive components account for 10-42% of total malignant NMEs. The factors associated with invasiveness on magnetic resonance imaging (MRI) could be useful for clinical assessment and treatment. Purpose To evaluate the clinical significances of the distributions and internal enhancement patterns (IEP) of malignant NMEs on 3-T breast MRI. Material and Methods A total of 448 consecutive women with newly diagnosed breast cancer that had undergone preoperative MRI and surgery between February 2013 and March 2016 were identified. After exclusions, 72 malignant NMEs without a mass in 72 women (mean age = 51.5 years) were included. Two readers independently assessed distributions and IEPs of NME, according to the Breast Imaging Reporting and Data System lexicon fifth edition. Collected data included the presence of invasion and histopathologic factors. Results A clustered ring IEP was significantly associated with invasive cancer (75.0%, P = 0.001, Reader1; 72.9%, P < 0.001, Reader 2), absence of necrosis (79.0%, P < 0.001; 72.1%, P < 0.001, respectively), and high Ki-67 expression (74.2%, P = 0.048; 74.2%, P = 0.003, respectively). A clumped IEP was related to ductal carcinoma in situ (33.3%, P = 0.025; 50.0%, P = 0.001, respectively), absence of lymph node metastasis (24.1%, P = 0.029; 31.5%, P = 0.030, respectively), and presence of necrosis (34.5%, P = 0.003; 44.8%, P = 0.001, respectively). Conclusion The presence of a clustered ring IEP in patients with breast cancer was found to be significantly associated with invasive breast cancer and high Ki-67 expression.

Computer-aided Diagnosis-generated Kinetic Features of Breast Cancer at Preoperative MR Imaging: Association with Disease-free Survival of Patients with Primary Operable Invasive Breast Cancer.

Purpose To retrospectively investigate the relationship between the kinetic features of breast cancer assessed with computer-aided diagnosis (CAD) at preoperative magnetic resonance (MR) imaging and disease-free survival in patients with primary operable invasive breast cancer. Materials and Methods This retrospective study was approved by the institutional review board. The requirement to obtain informed consent was waived. The authors identified 329 consecutive women (mean age, 52.9 years; age range, 32-88 years) with newly diagnosed invasive breast cancer who had undergone preoperative MR imaging and surgery between January 2012 and February 2013. All MR images were retrospectively reviewed by using a commercially available CAD system, and the following kinetic parameters were noted for each lesion: peak enhancement (highest pixel signal intensity in the first series obtained after administration of contrast material), angio-volume (total volume of the enhancing lesion), and delayed enhancement profiles (the proportions of washout, plateau, and persistently enhancing component within a tumor). Cox proportional hazards modeling was used to identify the relationship between CAD-generated kinetics and disease-free survival after adjusting for clinical-pathologic variables. Results A total of 36 recurrences developed at a median follow-up of 50 months (range, 15-55 months). CAD-measured peak enhancement at preoperative MR imaging enabled differentiation between patients with and patients without recurrence (area under the receiver operating characteristic curve = 0.728; 95% confidence interval [CI]: 0.676, 0.775; P < .001). Multivariate Cox analysis showed that a higher peak enhancement (hazard ratio [HR] = 1.001; 95% CI: 1.000, 1.002; P = .004), a higher washout component (HR = 1.029; 95% CI: 1.005, 1.054; P = .017), and lymphovascular invasion at histopathologic examination (HR = 3.011; 95% CI: 1.302, 6.962; P = .010) were associated with poorer disease-free survival. Conclusion Higher values of CAD-measured peak enhancement and washout component at preoperative MR imaging were significantly associated with poorer disease-free survival of patients with primary operable breast cancer. © RSNA, 2017.

Dynamic contrast-enhanced and diffusion-weighted MRI of estrogen receptor-positive invasive breast cancers: Associations between quantitative MR parameters and Ki-67 proliferation status.

PURPOSE: To explore the association between quantitative parameters derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion-weighted imaging (DWI) and Ki-67 proliferation status in patients with estrogen receptor (ER)-positive invasive breast cancer. MATERIALS AND METHODS: We retrospectively reviewed the records of 88 patients with ER-positive invasive breast cancer who underwent preoperative DCE-MRI and DWI on a 3T scanner. Perfusion parameters (Ktrans , Kep , and Ve ) and apparent diffusion coefficients (ADCs) were recorded, and we correlated these data with the Ki-67 status. The Ki-67 proliferation index was categorized as high (≥14%) or low (<14%). RESULTS: In the high-Ki-67 group, the mean Ktrans was significantly higher (P < 0.001) than that of the low-Ki-67 group, and the mean ADC significantly lower (P < 0.001). However, the mean Kep and Ve values did not differ between the two groups (P = 0.248 and P = 0.055, respectively). Univariate analysis showed that a higher Ktrans (>0.274), a lower ADC (≤0.893 × 10-3 mm2 /s), a larger tumor size (>2 cm), a higher histological grade (grade 3), the presence of axillary metastasis, and positive P53 status were significantly associated with high-Ki-67 status (all P values < 0.05). Of these variables, a higher Ktrans (>0.274; adjusted odds ratio [OR] = 9.027, 95% confidence interval [CI] = 1.929-42.245; P = 0.005) and a higher histological grade (grade 3; adjusted OR = 7.510, 95% CI = 1.305-43.205; P = 0.024) independently predicted a high Ki-67 status. CONCLUSION: Ktrans derived from DCE-MRI is associated independently with the Ki-67 proliferation status in patients with ER-positive invasive breast cancer. LEVEL OF EVIDENCE: 4 J. Magn. Reson. Imaging 2017;45:94-102.

Biologic Profiles of Invasive Breast Cancers Detected Only With Digital Breast Tomosynthesis.

OBJECTIVE: The purpose of this study was to analyze the clinicopathologic and immunohistochemical features of invasive breast cancers detected only with digital breast tomosynthesis (DBT), compared with those of cancers detected with both DBT and full-field digital mammography (FFDM). MATERIALS AND METHODS: The medical records of 261 women (108 without and 153 with symptoms) with invasive breast cancers who underwent FFDM and DBT between April 2015 and June 2016 were retrospectively reviewed. To assess detectability, all DBT and FFDM images were reviewed independently by three radiologists blinded to clinicopathologic information. The reference standard was established by an unblinded consensus review of all images. Clinicopathologic and immunohistochemical features were analyzed according to the detectability status. RESULTS: Of the 261 cancers, 223 (85.4%) were detected with both DBT and FFDM (both-detected group). Twenty-four cancers (9.2%) not detected with FFDM (DBT-only group) were classified by DBT as a mass (58.3%), architectural distortion (33.3%), or asymmetry (8.3%). The remaining 14 cancers (5.4%) were not detected with either DBT or FFDM (both-occult group). On multivariate analysis, a dense breast parenchyma (p = 0.007), small tumor size (≤ 2 cm; p = 0.027), and luminal A-like subtype (estrogen receptor positive or progesterone receptor positive or both, human epidermal growth factor receptor 2 negative, and Ki-67 expression < 14%; p = 0.008) were significantly associated with the DBT-only group. For 108 screening-detected cancers, a dense breast parenchyma (p = 0.007) and luminal A-like subtype (p = 0.008) also maintained significance. CONCLUSION: The addition of DBT to FFDM in screening would aid in the detection of less-aggressive subtypes of invasive breast cancers in women with dense breasts.