Hubert Bickel

Readout-segmented Echo-planar Imaging Improves the Diagnostic Performance of Diffusion-weighted MR Breast Examinations at 3.0 T

PURPOSE To qualitatively and quantitatively compare the diagnostic value of diffusion-weighted (DW) magnetic resonance (MR) imaging based on standard single-shot echo-planar imaging and readout-segmented echo-planar imaging in patients with breast cancer at 3.0 T. MATERIALS AND METHODS Institutional review board approval and written informed consent were obtained. Forty-seven patients with 49 histopathologically verified lesions were included in this study. In all patients, DW imaging, with single-shot echo-planar imaging and readout-segmented echo-planar imaging with comparable imaging parameters, was performed with a 3.0-T MR imager. Two independent readers visually assessed image quality and lesion conspicuity, and image properties (ie, signal-to-noise ratio, contrast, geometric distortions) were quantified. Regions of interest were drawn in all lesions (28 malignant, 21 benign) and in the normal breast parenchyma to investigate differences in apparent diffusion coefficient (ADC). Diagnostic accuracy was calculated on the basis of an ADC threshold of 1.25 × 10(-3) mm(2)/sec. RESULTS Each reader found a higher diagnostic accuracy for readout-segmented (96%) than for single-shot (90%) echo-planar imaging. The area under the curve for readout-segmented echo-planar imaging (0.981) was significantly larger than for single-shot echo-planar imaging (0.867) (P = .026). There was no significant difference in the ADC obtained by using either DW imaging method. Lesion conspicuity and image quality of readout-segmented echo-planar imaging were rated superior to those of single-shot echo-planar imaging (P < .001). Readout-segmented echo-planar imaging reduced geometric distortions by a factor of three. CONCLUSION DW imaging based on readout-segmented echo-planar imaging provided significantly higher image quality and lesion conspicuity than single-shot echo-planar imaging by reducing geometric distortions, image blurring, and artifact level with a clinical high-field-strength MR imager. Thereby, readout-segmented echo-planar imaging reached a higher diagnostic accuracy for the differentiation of benign and malignant breast lesions.

Improved diagnostic accuracy with multiparametric magnetic resonance imaging of the breast using dynamic contrast-enhanced magnetic resonance imaging, diffusion-weighted imaging, and 3-dimensional proton magnetic resonance spectroscopic imaging.

IntroductionThe purpose of this study was to compare the diagnostic accuracy of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) as a single parameter to multiparametric (MP) MRI with 2 (DCE MRI and diffusion-weighted imaging [DWI]) and 3 (DCE MRI, DWI, and 3-dimensional proton magnetic resonance spectroscopic imaging [3D 1H-MRSI]) parameters in breast cancer diagnosis. Materials and MethodsThis prospective study was approved by the institutional review board. Written informed consent was obtained in all patients. One hundred thirteen female patients (mean age, 52 years; range, 22–86 years) with an imaging abnormality (Breast Imaging Reporting and Data System 0, 4–5) were included in this study. Multiparametric MRI of the breast at 3 T with DCE MRI, DWI, and 3D 1H-MRSI was performed. The likelihood of malignancy was assessed for DCE MRI and MP MRI with 2 (DCE MRI and DWI) and 3 (DCE MRI, DWI, and 3D 1H-MRSI) parameters separately. Histopathology was used as the standard of reference. Appropriate statistical tests were used to assess sensitivity, specificity, and diagnostic accuracy for each assessment combination. ResultsThere were 74 malignant and 39 benign breast lesions. Multiparametric MRI with 3 MRI parameters yielded significantly higher areas under the curve (0.936) in comparison with DCE MRI alone (0.814) (P < 0.001). Multiparametric MRI with just 2 parameters at 3 T did not yield higher areas under the curve (0.808) than did DCE MRI alone (0.814). Multiparametric MRI with 3 parameters resulted in elimination of false-negative lesions and significantly reduced the false-positives ones (P = 0.002). ConclusionsMultiparametric MRI with 3 parameters increases the diagnostic accuracy of breast cancer in comparison with DCE-MRI alone and MP MRI with 2 parameters.

Improved Differentiation of Benign and Malignant Breast Tumors with Multiparametric 18Fluorodeoxyglucose Positron Emission Tomography Magnetic Resonance Imaging: A Feasibility Study

Purpose: To assess whether multiparametric 18fluorodeoxyglucose positron emission tomography magnetic resonance imaging (MRI) (MP 18FDG PET-MRI) using dynamic contrast-enhanced MRI (DCE-MRI), diffusion-weighted imaging (DWI), three-dimensional proton MR spectroscopic imaging (3D 1H-MRSI), and 18FDG-PET enables an improved differentiation of benign and malignant breast tumors. Experimental Design: Seventy-six female patients (mean age, 55.7 years; range, 25–86 years) with an imaging abnormality (BI-RADS 0, 4–5) were included in this Institutional Review Board (IRB)-approved study. Patients underwent fused PET-MRI of the breast with 18FDG-PET/CT and MP MRI at 3T. The likelihood of malignancy was assessed for all single parameters, for MP MRI with two/three parameters, and for MP 18FDG PET-MRI. Histopathology was used as the standard of reference. Appropriate statistical tests were used to assess sensitivity, specificity, and diagnostic accuracy for each assessment combination. Results: There were 53 malignant and 23 benign breast lesions. MP 18FDG PET-MRI yielded a significantly higher area under the cure (AUC) of 0.935 than DCE-MRI (AUC, 0.86; P = 0.044) and the combination of DCE-MRI and another parameter (AUC, 0.761–0.826; P = 0.013–0.020). MP 18FDG PET-MRI showed slight further improvement to MP MRI with three parameters (AUC, 0.925; P = 0.317). Using MP 18FDG PET-MRI there would have been a reduction of the unnecessary breast biopsies recommended by MP imaging with one or two parameters (P = 0.002–0.011). Conclusion: This feasibility study shows that MP 18FDG PET-MRI enables an improved differentiation of benign and malignant breast tumors when several MRI and PET parameters are combined. MP 18FDG PET-MRI may lead to a reduction in unnecessary breast biopsies. Clin Cancer Res; 20(13); 3540–9. ©2014 AACR.

Quantitative apparent diffusion coefficient as a noninvasive imaging biomarker for the differentiation of invasive breast cancer and ductal carcinoma in situ.

ObjectivesThe objective of this study was to evaluate whether apparent diffusion coefficient (ADC) obtained through diffusion-weighted imaging magnetic resonance imaging at 3 T can be used as an imaging biomarker to differentiate invasive breast cancer from noninvasive ductal carcinoma in situ (DCIS). Materials and MethodsOne hundred seventy-six histopathologically verified primary malignant breast tumors were retrospectively evaluated in 170 patients. All patients had undergone a standardized 3-T magnetic resonance imaging protocol, containing a diffusion-weighted sequence with 2 b values and a series of dynamic contrast-enhanced T1-weighted sequences. Apparent diffusion coefficient was measured manually by a reader blinded to the histopathological results. The ADC values were correlated with histopathological results. Mean ADC values were compared between invasive cancers and DCIS as well as between different tumor grades. Receiver operating characteristics curves were used to calculate diagnostic performance. ResultsThere were 155 invasive cancers and 21 noninvasive DCIS. Mean (SD) values differed significantly between the invasive cancers (0.9 [0.15] ×10−3 mm2/s) and the DCIS (1.24 [0.23] ×10−3 mm2/s, P < 0.001). Area under the receiver operating characteristics curve was 0.895 (95% confidence interval [CI], 0.840–0.936). A threshold of 1.01 ×10−3 mm2/s or less allowed an identification of invasive cancers with a sensitivity of 78.06% (95% CI, 70.7%–84.3%) and a specificity of 90.5% (95% CI, 69.6%–98.8%). No significant ADC differences were found among different tumor grades (P > 0.05). ConclusionsApparent diffusion coefficient could be used as an imaging biomarker for the diagnosis of breast cancer. It seems to be a valuable noninvasive quantitative biomarker to assess breast cancer invasiveness. Thus, ADC measurements provide the potential to reduce overdiagnosis and subsequent overtreatment.

Diffusion-weighted imaging of breast lesions: Region-of-interest placement and different ADC parameters influence apparent diffusion coefficient values

ObjectivesTo investigate the influence of region-of-interest (ROI) placement and different apparent diffusion coefficient (ADC) parameters on ADC values, diagnostic performance, reproducibility and measurement time in breast tumours.MethodsIn this IRB-approved, retrospective study, 149 histopathologically proven breast tumours (109 malignant, 40 benign) in 147 women (mean age 53.2) were investigated. Three radiologists independently measured minimum, mean and maximum ADC, each using three ROI placement approaches:1 – small 2D-ROI, 2 – large 2D-ROI and 3 – 3D-ROI covering the whole lesion. One reader performed all measurements twice. Median ADC values, diagnostic performance, reproducibility, and measurement time were calculated and compared between all combinations of ROI placement approaches and ADC parameters.ResultsMedian ADC values differed significantly between the ROI placement approaches (p < .001). Minimum ADC showed the best diagnostic performance (AUC .928–.956), followed by mean ADC obtained from 2D ROIs (.926–.94). Minimum and mean ADC showed high intra- (ICC .85–.94) and inter-reader reproducibility (ICC .74–.94). Median measurement time was significantly shorter for the 2D ROIs (p < .001).ConclusionsROI placement significantly influences ADC values measured in breast tumours. Minimum and mean ADC acquired from 2D-ROIs are useful for the differentiation of benign and malignant breast lesions, and are highly reproducible, with rapid measurement.Key Points• Region of interest placement significantly influences apparent diffusion coefficient of breast tumours.• Minimum and mean apparent diffusion coefficient perform best and are reproducible.• 2D regions of interest perform best and provide rapid measurement times.

Diffusion-weighted MRI of breast lesions: a prospective clinical investigation of the quantitative imaging biomarker characteristics of reproducibility, repeatability, and diagnostic accuracy.

Diffusion‐weighted MRI (DWI) provides insights into tissue microstructure by visualization and quantification of water diffusivity.

Molecular imaging for the characterization of breast tumors

Recently, molecular imaging, using various techniques, has been assessed for breast imaging. Molecular imaging aims to quantify and visualize biological, physiological, and pathological processes at the cellular and molecular levels to further elucidate the development and progression of breast cancer and the response to treatment. Molecular imaging enables the depiction of tumor morphology, as well as the assessment of functional and metabolic processes involved in cancer development at different levels. To date, molecular imaging techniques comprise both nuclear medicine and radiological techniques. This review aims to summarize the current and emerging functional and metabolic techniques for the molecular imaging of breast tumors.

Respiratory motion artifacts during arterial phase imaging with gadoxetic acid: Can the injection protocol minimize this drawback?

To determine which of three gadoxetic acid injection techniques best reduced the contrast‐related arterial‐phase motion artifacts.

Accuracy of fully automated, quantitative, volumetric measurement of the amount of fibroglandular breast tissue using MRI: correlation with anthropomorphic breast phantoms

To demonstrate the accuracy of fully automated, quantitative, volumetric measurement of the amount of fibroglandular breast tissue (FGT), using MRI, and to investigate the impact of different MRI sequences using anthropomorphic breast phantoms as the ground truth.

Influence of fat-water separation and spatial resolution on automated volumetric MRI measurements of fibroglandular breast tissue.

The aim of this study was to investigate the influence of fat–water separation and spatial resolution in MRI on the results of automated quantitative measurements of fibroglandular breast tissue (FGT). Ten healthy volunteers (age range, 28–71 years; mean, 39.9 years) were included in this Institutional Review Board‐approved prospective study. All measurements were performed on a 1.5‐T scanner (Siemens, AvantoFit) using an 18‐channel breast coil. The protocols included isotropic (Di) [TR/TE1/TE2 = 6.00 ms/2.45 ms/2.67 ms; flip angle, 6.0°; 256 slices; matrix, 360 × 360; 1 mm isotropic; field of view, 360°; acquisition time (TA) = 3 min 38 s] and anisotropic (Da) (TR/TE1/TE2 = 10.00 ms/2.39 ms/4.77 ms; flip angle, 24.9°; 80 slices; matrix 360 × 360; voxel size, 0.7 × 0.7 × 2.0 mm3; field of view, 360°; TA = 1 min 25 s) T1 three‐dimensional (3D) fast low‐angle shot (FLASH) Dixon sequences, and a T1 3D FLASH sequence with the same resolution (T1) without (TR/TE = 11.00 ms/4.76 ms; flip angle, 25.0°; 80 slices; matrix, 360 × 360; voxel size, 0.7 × 0.7 × 2.0 mm3; field of view, 360°; TA = 50 s) and with (TR/TE = 29.00 ms/4.76 ms; flip angle, 25.0°; 80 slices; matrix, 360 × 360; voxel size, 0.7 × 0.7 × 2.0 mm3; field of view, 360°; TA = 2 min 35 s) fat saturation. Repeating volunteer measurements after 20 min and repositioning were used to assess reproducibility. An automated and quantitative volumetric breast density measurement system was used for FGT calculation. FGT with Di, Da and T1 measured 4.6–63.0% (mean, 30.6%), 3.2–65.3% (mean, 32.5%) and 1.7–66.5% (mean, 33.7%), respectively. The highest correlation between different MRI sequences was found with the Di and Da sequences (R2 = 0.976). Coefficients of variation (CVs) for FGT calculation were higher in T1 (CV = 21.5%) compared with Dixon (Di, CV = 5.1%; Da, CV = 4.2%) sequences. Dixon‐type sequences worked well for FGT measurements, even at lower resolution, whereas the conventional T1‐weighted sequence was more sensitive to decreasing resolution. The Dixon fat–water separation technique showed superior repeatability of FGT measurements compared with conventional sequences. A standard dynamic protocol using Dixon fat–water separation is best suited for combined diagnostic purposes and prognostic measurements of FGT. Copyright