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Diffusion-weighted imaging (DWI) may allow for breast cancer screening MRI without a contrast injection. Multishot methods improve prone DWI of the breasts but face different challenges in the supine position.To establish a multishot DWI (msDWI) protocol for supine breast MRI and to evaluate the performance of supine vs. prone msDWI.Prospective.Protocol optimization: 10 healthy women (ages 22-56), supine vs. prone: 24 healthy women (ages 22-62) and five women (ages 29-61) with breast tumors.3-T, protocol optimization msDWI: free-breathing (FB) 2-shots, FB 4-shots, respiratory-triggered (RT) 2-shots, RT 4-shots, supine vs. prone: RT 4-shot msDWI, T2-weighted fast-spin echo.Protocol optimization and supine vs. prone: three observers performed an image quality assessment of sharpness, aliasing, distortion (vs. T2), perceived SNR, and overall image quality (scale of 1-5). Apparent diffusion coefficients (ADCs) in fibroglandular tissue (FGT) and breast tumors were measured.Effect of study variables on dichotomized ratings (4/5 vs. 1/2/3) and FGT ADCs were assessed with mixed-effects logistic regression. Interobserver agreement utilized Gwet's agreement coefficient (AC). Lesion ADCs were assessed by Bland-Altman analysis and concordance correlation (ρProtocol optimization: 4-shots significantly improved sharpness and distortion; RT significantly improved sharpness, aliasing, perceived SNR, and overall image quality. FGT ADCs were not significantly different between shots (P = 0.812), FB vs. RT (P = 0.591), or side (P = 0.574). Supine vs. prone: supine images were rated significantly higher for sharpness, aliasing, and overall image quality. FGT ADCs were significantly higher supine; lesion ADCs were highly correlated (ρBased on image quality, supine msDWI outperformed prone msDWI. Lesion ADCs were highly correlated between the two positions, while FGT ADCs were higher in the supine position.2.Stage 1.

The image quality limitations of echo-planar diffusion-weighted imaging (DWI) are an obstacle to its widespread adoption in the breast. Steady-state DWI is an alternative DWI method with more robust image quality but its contrast for imaging breast cancer is not well-understood. The aim of this study was to develop and evaluate diffusion-weighted double-echo steady-state imaging with a three-dimensional cones trajectory (DW-DESS-Cones) as an alternative to conventional DWI for non-contrast-enhanced MRI in the breast. This prospective study included 28 women undergoing clinically indicated breast MRI and six asymptomatic volunteers. In vivo studies were performed at 3 T and included DW-DESS-Cones, DW-DESS-Cartesian, DWI, and CE-MRI acquisitions. Phantom experiments (diffusion phantom, High Precision Devices) and simulations were performed to establish framework for contrast of DW-DESS-Cones in comparison to DWI in the breast. Motion artifacts of DW-DESS-Cones were measured with artifact-to-noise ratio in volunteers and patients. Lesion-to-fibroglandular tissue signal ratios were measured, lesions were categorized as hyperintense or hypointense, and an image quality observer study was performed in DW-DESS-Cones and DWI in patients. Effect of DW-DESS-Cones method on motion artifacts was tested by mixed-effects generalized linear model. Effect of DW-DESS-Cones on signal in phantom was tested by quadratic regression. Correlation was calculated between DW-DESS-Cones and DWI lesion-to-fibroglandular tissue signal ratios. Inter-observer agreement was assessed with Gwet’s AC. Simulations predicted hyperintensity of lesions with DW-DESS-Cones but at a 3% to 67% lower degree than with DWI. Motion artifacts were reduced with DW-DESS-Cones versus DW-DESS-Cartesian (p < 0.05). Lesion-to-fibroglandular tissue signal ratios were not correlated between DW-DESS-Cones and DWI (r = 0.25, p = 0.38). Concordant hyperintensity/hypointensity was observed between DW-DESS-Cones and DWI in 11/14 lesions. DW-DESS-Cones improved sharpness, distortion, and overall image quality versus DWI. DW-DESS-Cones may be able to eliminate motion artifacts in the breast allowing for investigation of higher degrees of steady-state diffusion weighting. Malignant breast lesions in DW-DESS-Cones demonstrated hyperintensity with respect to surrounding tissue without an injection of contrast. LEVEL OF EVIDENCE: 2. TECHNICAL EFFICACY STAGE: 1.

BACKGROUND Diffusion-weighted imaging (DWI) has shown promise to screen for breast cancer without a contrast injection, but image distortion and low spatial resolution limit standard single-shot DWI. Multishot DWI methods address these limitations but introduce shot-to-shot phase variations requiring correction during reconstruction. PURPOSE To investigate the performance of two multishot DWI reconstruction methods, multiplexed sensitivity encoding (MUSE) and shot locally low-rank (shot-LLR), compared to single-shot DWI in the breast. STUDY TYPE Prospective. POPULATION A total of 45 women who consented to have multishot DWI added to a clinically indicated breast MRI. FIELD STRENGTH/SEQUENCES Single-shot DWI reconstructed by parallel imaging, multishot DWI with four or eight shots reconstructed by MUSE and shot-LLR, 3D T2 -weighted imaging, and contrast-enhanced MRI at 3T. ASSESSMENT Three blinded observers scored images for 1) general image quality (perceived signal-to-noise ratio [SNR], ghosting, distortion), 2) lesion features (discernment and morphology), and 3) perceived resolution. Apparent diffusion coefficient (ADC) of the lesion was also measured and compared between methods. STATISTICAL TESTS Image quality features and perceived resolution were assessed with a mixed-effects logistic regression. Agreement among observers was estimated with a Krippendorf's alpha using linear weighting. Lesion feature ratings were visualized using histograms, and correlation coefficients of lesion ADC between different methods were calculated. RESULTS MUSE and shot-LLR images were rated to have significantly better perceived resolution (P

Purpose To accelerate and improve multishot diffusion-weighted MRI reconstruction using deep learning. Methods An unrolled pipeline containing recurrences of model-based gradient updates and neural networks was introduced for accelerating multishot DWI reconstruction with shot-to-shot phase correction. The network was trained to predict results of jointly reconstructed multidirection data using single-direction data as input. In vivo brain and breast experiments were performed for evaluation. Results The proposed method achieves a reconstruction time of 0.1 second per image, over 100-fold faster than a shot locally low-rank reconstruction. The resultant image quality is comparable to the target from the joint reconstruction with a peak signal-to-noise ratio of 35.3 dB, a normalized root-mean-square error of 0.0177, and a structural similarity index of 0.944. The proposed method also improves upon the locally low-rank reconstruction (2.9 dB higher peak signal-to-noise ratio, 29% lower normalized root-mean-square error, and 0.037 higher structural similarity index). With training data from the brain, this method also generalizes well to breast diffusion-weighted imaging, and fine-tuning further reduces aliasing artifacts. Conclusion A proposed data-driven approach enables almost real-time reconstruction with improved image quality, which improves the feasibility of multishot DWI in a wide range of clinical and neuroscientific studies.

Purpose The goal of this work is to propose a motion robust reconstruction method for diffusion-weighted MRI that resolves shot-to-shot phase mismatches without using phase estimation. Methods Assuming that shot-to-shot phase variations are slowly varying, spatial-shot matrices can be formed using a local group of pixels to form columns, in which each column is from a different shot (excitation). A convex model with a locally low-rank constraint on the spatial-shot matrices is proposed. In vivo brain and breast experiments were performed to evaluate the performance of the proposed method. Results The proposed method shows significant benefits when the motion is severe, such as for breast imaging. Furthermore, the resulting images can be used for reliable phase estimation in the context of phase-estimation-based methods to achieve even higher image quality. Conclusion We introduced the shot-locally low-rank method, a reconstruction technique for multishot diffusion-weighted MRI without explicit phase estimation. In addition, its motion robustness can be beneficial to neuroimaging and body imaging.

Purpose To develop a radial, double-echo steady-state (DESS) sequence with ultra-short echo-time (UTE) capabilities for T2 measurement of short-T2 tissues along with simultaneous rapid, signal-to-noise ratio (SNR)-efficient, and high-isotropic-resolution morphological knee imaging. Methods THe 3D radial UTE readouts were incorporated into DESS, termed UTEDESS. Multiple-echo-time UTEDESS was used for performing T2 relaxometry for short-T2 tendons, ligaments, and menisci; and for Dixon water-fat imaging. In vivo T2 estimate repeatability and SNR efficiency for UTEDESS and Cartesian DESS were compared. The impact of coil combination methods on short-T2 measurements was evaluated by means of simulations. UTEDESS T2 measurements were compared with T2 measurements from Cartesian DESS, multi-echo spin-echo (MESE), and fast spin-echo (FSE). Results UTEDESS produced isotropic resolution images with high SNR efficiency in all short-T2 tissues. Simulations and experiments demonstrated that sum-of-squares coil combinations overestimated short-T2 measurements. UTEDESS measurements of meniscal T2 were comparable to DESS, MESE, and FSE measurements while the tendon and ligament measurements were less biased than those from Cartesian DESS. Average UTEDESS T2 repeatability variation was under 10% in all tissues. Conclusion The T2 measurements of short-T2 tissues and high-resolution morphological imaging provided by UTEDESS makes it promising for studying the whole knee, both in routine clinical examinations and longitudinal studies. Magn Reson Med 78:2136–2148, 2017. © 2017 International Society for Magnetic Resonance in Medicine.

PURPOSE: To develop a near-silent and distortionless diffusion-weighted imaging (sd-DWI) sequence using magnetization prepared rotating ultra-fast imaging sequence (RUFIS). METHODS: A rotating ultra-fast imaging sequence was modified with driven-equilibrium diffusion preparation, including eddy-current compensation methods. To compensate for the T(1) recovery during readout, a phase-cycling method was used. Both compensation methods were validated in phantoms. The optimized sequence was compared with an echo-planar imaging (EPI) diffusion sequence for image distortion, contrast, apparent diffusion coefficient (ADC) and acoustic noise level in phantoms. The sequence was evaluated in brain volunteer, five prostate volunteers, and ten pediatric patients with joint diseases. RESULTS: Combination of several eddy-current compensation methods reduced the artifact to an acceptable level. Phase-cycling reduced T(1) recovery contamination during readout. In phantom scans, the optimized sequence generated similar image contrast to the EPI diffusion sequence and ADC maps between the sequences were comparable, sd-DWI had significantly lower acoustic noise (p < 0.05). In-vivo brain scan showed reduced image distortion in sd-DWI compared to the EPI diffusion, though residual motion artifact remains due to brain pulsation. The prostate scans showed sd-DWI can provide similar ADC compared to EPI diffusion, with no image distortion. Patient scans showed the sequence can clearly depict joint lesions. CONCLUSION: A sd-DWI sequence was developed and optimized. Compared to conventional EPI diffusion, sd-DWI provided similar diffusion contrast, accurate ADC measurement, improved image quality, and minimal ambient scanning noise. The sequence showed the ability to obtain in-vivo diffusion contrast in relatively motion-free body regions, such as prostate and joint.

Purpose To determine whether T2-weighted MRI improves seroma cavity (SC) and whole breast (WB) interobserver conformity for radiation therapy purposes, compared with the gold standard of CT, both in the prone and supine positions. Methods and Materials Eleven observers (2 radiologists and 9 radiation oncologists) delineated SC and WB clinical target volumes (CTVs) on T2-weighted MRI and CT supine and prone scans (4 scans per patient) for 33 patient datasets. Individual observer's volumes were compared using the Dice similarity coefficient, volume overlap index, center of mass shift, and Hausdorff distances. An average cavity visualization score was also determined. Results Imaging modality did not affect interobserver variation for WB CTVs. Prone WB CTVs were larger in volume and more conformal than supine CTVs (on both MRI and CT). Seroma cavity volumes were larger on CT than on MRI. Seroma cavity volumes proved to be comparable in interobserver conformity in both modalities (volume overlap index of 0.57 (95% Confidence Interval (CI) 0.54-0.60) for CT supine and 0.52 (95% CI 0.48-0.56) for MRI supine, 0.56 (95% CI 0.53-0.59) for CT prone and 0.55 (95% CI 0.51-0.59) for MRI prone); however, after registering modalities together the intermodality variation (Dice similarity coefficient of 0.41 (95% CI 0.36-0.46) for supine and 0.38 (0.34-0.42) for prone) was larger than the interobserver variability for SC, despite the location typically remaining constant. Conclusions Magnetic resonance imaging interobserver variation was comparable to CT for the WB CTV and SC delineation, in both prone and supine positions. Although the cavity visualization score and interobserver concordance was not significantly higher for MRI than for CT, the SCs were smaller on MRI, potentially owing to clearer SC definition, especially on T2-weighted MR images.

PurposeTo investigate the diagnostic accuracy and clinical usefulness of the rim sign in breast lesions observed in diffusion-weighted magnetic resonance imaging (DWI). Materials and MethodsThe magnetic resonance imaging (MRI) findings of 98 pathologically confirmed lesions (62 malignant and 36 benign) in 84 patients were included. Five breast radiologists were asked to independently review the breast MRI results, to grade the degree of high peripheral signal, the rim sign, in the DWI, and to confirm the mean apparent diffusion coefficient (ADC(mean)) values. We analyzed the diagnostic accuracy and compared the consensus (when 4 of 5 independent reviewers agreed) results of the rim sign with the ADC(mean) values. Additionally, we evaluated the correlation between the dynamic contrast-enhanced (DCE)-MRI morphologic appearance and DWI rim sign. ResultsAccording to the consensus results, the rim sign in DWI was observed on 59.7% of malignant lesions and 19.4% of benign lesions. The sensitivity, specificity, and area under the curve (AUC) value for the rim sign in DWI were 59.7%, 80.6%, and 0.701, respectively. The sensitivity, specificity, and AUC value for the ADC(mean) value (criteria 1.46 x 10(-3) mm(2)/sec) were 82.3%, 63.9%, and 0.731, respectively. Based on consensus, no correlation was observed between the DCE-MRI and DWI rim signs. ConclusionIn DWI, a high-signal rim is a valuable morphological feature for improving specificity in DWI. J. Magn. Reson. Imaging 2015;41:616-623. (c) 2014 Wiley Periodicals, Inc.

Purpose To evaluate the performance of 2D versus 3D T2-weighted spin echo imaging in the breast. Materials and Methods 2D and 3D T2-weighted images were acquired in 25 patients as part of a clinically indicated breast magnetic resonance imaging (MRI) exam. Lesion-to-fibroglandular tissue signal ratio was measured in 16 identified lesions. Clarity of lesion morphology was assessed through a blinded review by three radiologists. Instances demonstrating the potential diagnostic contribution of 3D versus 2D T2-weighted imaging in the breast were noted through unblinded review by a fourth radiologist. Results The lesion-to-fibroglandular tissue signal ratio was well correlated between 2D and 3D T2-weighted images (R2 = 0.93). Clarity of lesion morphology was significantly better with 3D T2-weighted imaging for all observers based on a McNemar test (P ≤ 0.02, P ≤ 0.01, P ≤ 0.03). Instances indicating the potential diagnostic contribution of 3D T2-weighted imaging included improved depiction of signal intensity and improved alignment between DCE and T2-weighted findings. Conclusion In this pilot study, 3D T2-weighted imaging provided comparable contrast and improved depiction of lesion morphology in the breast in comparison to 2D T2-weighted imaging. Based on these results further investigation to determine the diagnostic impact of 3D T2-weighted imaging in breast MRI is warranted. J. Magn. Reson. Imaging 2014;39:332–338. © 2013 Wiley Periodicals, Inc.

Radial trajectories facilitate high-resolution balanced steady state free precession (bSSFP) because the efficient gradients provide more time to extend the trajectory in k-space. A number of radial bSSFP methods that support fat-water separation have been developed; however, most of these methods require an environment with limited B0 inhomogeneity. In this work, high-resolution bSSFP with fat-water separation is achieved in more challenging B0 environments by combining a 3D radial trajectory with the IDEAL chemical species separation method. A method to maintain very high resolution within the timing constraints of bSSFP and IDEAL is described using a dual-pass pulse sequence. The sampling of a unique set of radial lines at each echo time is investigated as a means to circumvent the longer scan time that IDEAL incurs as a multiecho acquisition. The manifestation of undersampling artifacts in this trajectory and their effect on chemical species separation are investigated in comparison to the case in which each echo samples the same set of radial lines. This new bSSFP method achieves 0.63 mm isotropic resolution in a 5-min scan and is demonstrated in difficult in vivo imaging environments, including the breast and a knee with ACL reconstruction hardware at 1.5 T.

To develop a radial, double-echo steady-state (DESS) sequence with ultra-short echo-time (UTE) capabilities for TTHe 3D radial UTE readouts were incorporated into DESS, termed UTEDESS. Multiple-echo-time UTEDESS was used for performing TUTEDESS produced isotropic resolution images with high SNR efficiency in all short-TThe T

Contrast-enhanced breast MRI screening is recommended for women with an increased risk of breast cancer because it has much higher sensitivity than x-ray mammography [1]. Multislice diffusion weighted echo-planar imaging (DW-EPI) has been reported as a way to detect some mammographically-occult breast cancers without need for intravenous contrast material [2], however the spatial resolution of the EPI technique is low compared to standard contrast-enhanced 3D sequences. Recently, we developed a new 3D diffusion weighted dual-echo steady-state (DESS) imaging sequence that produces high-resolution diffusion weighted images of the breast [3]. The purpose of this study is to evaluate the ability DESS to image breast cancer without intravenous contrast material.

PURPOSE: To investigate the diagnostic accuracy and clinical usefulness of the rim sign in breast lesions observed in diffusion-weighted magnetic resonance imaging (DWI). MATERIALS AND METHODS: The magnetic resonance imaging (MRI) findings of 98 pathologically confirmed lesions (62 malignant and 36 benign) in 84 patients were included. Five breast radiologists were asked to independently review the breast MRI results, to grade the degree of high peripheral signal, the “rim sign”, in the DWI, and to confirm the mean apparent diffusion coefficient (ADC(mean)) values. We analyzed the diagnostic accuracy and compared the consensus (when ≥ 4 of 5 independent reviewers agreed) results of the rim sign with the ADC(mean) values. Additionally, we evaluated the correlation between the DCE-MRI morphologic appearance and DWI rim sign. RESULTS: According to the consensus results, the rim sign in DWI was observed on 59.7% of malignant lesions and 19.4% of benign lesions. The sensitivity, specificity, and area under the curve (AUC) value for the rim sign in DWI were 59.7%, 80.6%, and 0.701, respectively. The sensitivity, specificity, and AUC value for the ADC(mean) value (criteria ≤ 1.46 × 10(−3) mm(2)/sec) were 82.3%, 63.9%, and 0.731, respectively. Based on consensus, no correlation was observed between the DCE-MRI and DWI rim signs. CONCLUSION: In DWI, a high-signal rim is a valuable morphological feature for improving specificity in DWI.

To compare the image quality of three techniques and diagnostic performance in detecting implant rupture.The study included 161 implants for the evaluation of image quality, composed of water-saturated short TI inversion recovery (herein called "water-sat STIR"), three-point Dixon techniques (herein called "Dixon"), and short TI inversion recovery fast spin-echo with iterative decomposition of silicone and water using least-squares approximation (herein called "STIR IDEAL") and included 41 implants for the evaluation of diagnostic performance in detecting rupture, composed of water-sat STIR and STIR IDEAL. Six image quality categories were evaluated and three classifications were used: normal implant, possible rupture, and definite rupture.Statistically significant differences were noted for the image quality categories (p0.001). STIR IDEAL was superior or equal to water-sat STIR in all image quality categories except artifact effects and superior to Dixon in all categories. Water-sat STIR performed the poorest for water suppression uniformity. The sensitivity and specificity in detecting implant rupture of STIR-IDEAL were 81.8 % and 77.8 % and the difference between two techniques was not statistically significant.STIR-IDEAL is a useful silicone-specific imaging technique demonstrating more robust water suppression and equivalent diagnostic accuracy for detecting implant rupture, than water-sat STIR, at the cost of longer scan time and an increase in minor motion artifacts.

High spatial resolution is advantageous for lesion characterization in breast MRI as depiction of fine lesion morphology can help to distinguish a lesion as benign or malignant. In particular, increased spatial resolution may be beneficial in the case of ancillary enhancing foci that can greatly complicate the efficacy of breast MRI [1,2]. In fact, currently, many radiologists do not even attempt to diagnose ancillary enhancing foci of less than 5mm due to the lack of lesion characterization information available for lesions of this size. While a number of methods have been developed that improve spatial resolution or provide a means to improve spatial resolution, two factors must be incorporated for these methods to be clinically accessible. First, improved spatial resolution must be achieved while maintaining clinically feasible scan times and second, improved spatial resolution must be achieved across all contrast mechanisms that are routinely utilized for lesion characterization. In this article we describe our work to achieve high spatial resolution across three contrast mechanisms (T1-weighted dynamic contrast enhanced (DCE), T2-weighted, and Diffusion-weighted) while maintaining clinically feasible scan times.

Radial trajectories facilitate high-resolution balanced steady state free precession (bSSFP) because the efficient gradients provide more time to extend the trajectory in k-space. A number of radial bSSFP methods that support fat-water separation have been developed; however, most of these methods require an environment with limited B0 inhomogeneity. In this work, high-resolution bSSFP with fat-water separation is achieved in more challenging B0 environments by combining a 3D radial trajectory with the IDEAL chemical species separation method. A method to maintain very high resolution within the timing constraints of bSSFP and IDEAL is described using a dual-pass pulse sequence. The sampling of a unique set of radial lines at each echo time is investigated as a means to circumvent the longer scan time that IDEAL incurs as a multi-echo acquisition. The manifestation of undersampling artifacts in this trajectory and their effect on chemical species separation are investigated in comparison to the case in which each echo samples the same set of radial lines. This new bSSFP method achieves 0.63 mm isotropic resolution in a 5-minute scan and is demonstrated in difficult in vivo imaging environments, including the breast and a knee with ACL reconstruction hardware at 1.5 T.

Purpose To assess a 3D radial balanced steady-state free precession (SSFP) technique that provides submillimeter isotropic resolution and inherently registered fat and water image volumes in comparison to conventional T2-weighted RARE imaging for lesion characterization in breast magnetic resonance imaging (MRI). Materials and Methods 3D projection SSFP (3DPR-SSFP) combines a dual half-echo radial k-space trajectory with a linear combination fat/water separation technique (linear combination SSFP). A pilot study was performed in 20 patients to assess fat suppression and depiction of lesion morphology using 3DPR-SSFP. For all patients fat suppression was measured for the 3DPR-SSFP image volumes and depiction of lesion morphology was compared against corresponding T2-weighted fast spin echo (FSE) datasets for 15 lesions in 11 patients. Results The isotropic 0.63 mm resolution of the 3DPR-SSFP sequence demonstrated improved depiction of lesion morphology in comparison to FSE. The 3DPR-SSFP fat and water datasets were available in a 5-minute scan time while average fat suppression with 3DPR-SSFP was 71% across all 20 patients. Conclusion 3DPR-SSFP has the potential to improve the lesion characterization information available in breast MRI, particularly in comparison to conventional FSE. A larger study is warranted to quantify the effect of 3DPR-SSFP on specificity. J. Magn. Reson. Imaging 2009;30:135–144. © 2009 Wiley-Liss, Inc.

During the last eight years our group has developed radial acquisitions with angular undersampling factors of several hundred that accelerate MRI in selected applications. As with all previous acceleration techniques, SNR typically falls as least as fast as the inverse square root of the undersampling factor. This limits the SNR available to support the small voxels that these methods can image over short time intervals in applications like time-resolved contrast-enhanced MR angiography (CE-MRA). Instead of processing each time interval independently, we have developed constrained reconstruction methods that exploit the significant correlation between temporal sampling points. A broad class of methods, termed HighlY Constrained Back PRojection (HYPR), generalizes this concept to other modalities and sampling dimensions.

Helical computed tomography (CT) is the most sensitive imaging modality for detection of pulmonary nodules. However, a single CT examination produces a large quantity of image data. Therefore, a computerized scheme has been developed to automatically detect pulmonary nodules on CT images. This scheme includes both two- and three-dimensional analyses. Within each section, gray-level thresholding methods are used to segment the thorax from the background and then the lungs from the thorax. A rolling ball algorithm is applied to the lung segmentation contours to avoid the loss of juxtapleural nodules. Multiple gray-level thresholds are applied to the volumetric lung regions to identify nodule candidates. These candidates represent both nodules and normal pulmonary structures. For each candidate, two- and three-dimensional geometric and gray-level features are computed. These features are merged with linear discriminant analysis to reduce the number of candidates that correspond to normal structures. This method was applied to a 17-case database. Receiver operating characteristic (ROC) analysis was used to evaluate the automated classifier. Results yielded an area under the ROC curve of 0.93 in the task of classifying candidates detected during thresholding as nodules or nonnodules.

We are developing a fully automated method for the detection of lung nodules in helical computed tomography (CT) images of the thorax. In our computerized method, gray-level thresholding is used to segment the lungs from the thorax region within each CT section. A rolling ball operation is employed to more accurately delineate the lung boundaries, thereby incorporating peripheral nodules within the segmented lung regions. A multiple gray-level thresholding scheme is then used to capture nodules by creating a series of binary images in which a pixel is turned `on' if the corresponding image pixel has a gray level greater than the selected threshold. Groups of contiguous `on' pixels are identified as individual signals. To distinguish nodules from vessels, geometric descriptors are calculated for each signal detected in the series of binary images. The values of these descriptors are input to an artificial neural network, which allows for the elimination of a high percentage of false-positive signals.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Although general rules for the differentiation between benign and malignant mammographically-identified breast lesions exist, considerable misclassification of lesions occurs with current imaging and interpretation methods [1]–[6]. The purpose of our study is to develop computerized methods for the analysis of mass lesions on digitized mammograms and on ultrasound images for aiding in the task of distinguishing between malignant and benign lesions. This should lead to (1) an improvement in the classification sensitivity for malignant lesions and (2) an increase in the classification specificity and thus, a reduction in the number of unnecessary biopsies. Higher performance is expected when a combination of features from mammographie and ultrasound images is used as an aid to radiologists in the task of distinguishing between malignant and benign lesions.

Purpose: The delineation of treatment volumes for breast cancer radiotherapy utilising standard CT images is associated with significant inter‐observer variability. It has been proposed that MRI with improved quality soft tissue definition may reduce this inter‐observer variability. The purpose of this study was to determine the optimum set‐up and sequence for MRI‐defined radiotherapy volume delineation. Methods: Six observers (2 radiologists, 4 radiation oncologists) were asked to score MRI quality for the purposes of radiotherapy delineation using the following scoring criteria where 0 — margin not recognisable (inability to discriminate) through to a score of 3, when margins were distinct (excellent discrimination). Supine breast MRI was achieved using a foam bridge to support a surface coil without touching the patient surface. T1 and T2 sequences were compared for both 1.5Tesla (1.5T) and 3T MRIs for a volunteer. Prone breast images were obtained using a 4 channel breast coil. Supine and prone breast MRIs were compared for T1 and T2 sequences for 3T for 2 volunteers. Results: Supine breast images were shown to be acceptable for the purpose of radiotherapy delineation with the 3T 2D T2 turbo spin echo sequences scoring 2s (fair discrimination) and 3s (excellent discrimination), most optimal. The prone 3D T1 gradient echo was the optimum of the supine and prone 3T images, however results were inconsistent with this sequence receiving a score of zero from one observer. Conclusion: Supine breast MRI scans can be achieved for the purpose of radiotherapy delineation. Scoring between observers was inconsistent when comparing scan sequences. This work has been supported by project grant 1033237 from Cancer Australia and The National Breast Cancer Foundation

Background: Although the dynamic contrast enhanced (DCE) sequence has long been considered the most important sequence to characterize benign and malignant breast processes with diagnostic breast MRI, the T2-weighted sequence can serve as a critical adjunctive sequence and improve the discriminating power of the interpreting radiologist. However, conventional T2-weighted acquisitions have inherent timing requirements that limit the resolution available in comparison to DCE images. Recently, 3D T2-weighted sequences have been developed that utilize modulated flip angle schedules and parallel imaging to provide higher resolution T2-weighted images in clinically feasible scan times (Hennig, J, et al., MRM 2003, Mugler, JP, et al., Radiology 2000, Busse, RF, et al., MRM 2006). While utilization of modulated flip angles allows for improved acquisition efficiency, contrast is potentially less purely T2-weighted. The goal of this study is to provide an initial assessment of a 3D T2-weighted acquisition (CUBE) (Busse, RF, et al., MRM 2006) in comparison to a conventional 2D Fast Spin Echo (FSE) in the breast Methods: Twenty-seven patients undergoing clinical MRI were scanned at 3T with both FSE and CUBE sequences as part of their exam. A total of 16 lesions were identified based on pathology (9 lesions) or on contrast-enhanced image assessment and/or stability from prior studies (7 lesions). Six lesions were malignant (all IDC) and 10 were benign (5 fibroadenomas, 4 cysts, 1 papilloma). Scan time (5 minutes) and in-plane resolution were equivalent between the CUBE and FSE images while slice thickness in CUBE (2 mm) was half that of FSE (4 mm). Lesion-to-fibroglandular tissue signal ratios (SL/SF) were calculated for both FSE and CUBE; SL is lesion signal and SF is fibroglandular tissue signal. The signal ratios were assessed with ordinary least squares linear regression. Along with lesion signal intensity with respect to surrounding tissue, depiction of lesion morphology on T2-weighted images can also contribute to differential diagnosis in breast MRI. A radiologist with breast MRI expertise evaluated the resolution difference between the two sequences based on the depiction of lesion morphology and the alignment of lesions between the T2-weighted and DCE images Results: SL/SF showed a correlation coefficient between the two methods of 0.93. Mean values of SL/SF for different methods and lesions were, FSE malignant: 1.01 ± 0.21, FSE benign: 2.05 ± 0.65, CUBE malignant 0.99 ± 0.25, CUBE benign 2.16 ± 0.62. Depiction of lesion morphology and signal intensity in small lesions improved in the CUBE images due to the reduced partial volume effect in the slice direction. Alignment of structures between T2-weighted and DCE images was facilitated with CUBE due to the higher through-plane resolution and the ability to reformat the images in orientations other than the acquisition plane. Conclusion: CUBE provides equivalent contrast and improved resolution in the breast in comparison to FSE. While T2-weighted images will continue to be an adjunct to DCE images, 3D T2-weighted sequences like CUBE have the potential to expand the contribution of T2-weighted images to the characterization of benign and malignant lesions in the breast. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-01-06.

Rationale and Objectives. Breast sonography is not routinely used to distinguish benign from malignant solid masses because of considerable overlap in their sonographic appearances. The purpose of this study was to investigate the computerized analyses of breast lesions in ultrasonographic (US) images in order to ultimately aid in the task of discriminating between malignant and benign lesions. Materials and Methods. Features related to lesion margin, shape, homogeneity (texture), and posterior acoustic attenuation pattern in US images of the breast were extracted and calculated. The study database contained 184 digitized US images from 58 patients with 78 lesions. Benign lesions were confirmed at biopsy or cyst aspiration or with image interpretation alone; malignant lesions were confirmed at biopsy. Performance of the various individual features and output from linear discriminant analysis in distinguishing benign from malignant lesions was studied by using receiver operating characteristic (ROC) analysis. Results. At ROC analysis, the feature characterizing the margin yielded A z values (area under the ROC curve) of 0.85 and 0.75 in distinguishing between benign and malignant lesions for the entire database and for an “equivocal” database, respectively. The equivocal database contained lesions that had been proved to be benign or malignant at cyst aspiration or biopsy. Linear discriminant analysis round-robin runs yielded A z values of 0.94 and 0.87 in distinguishing benign from malignant lesions for the entire database and for the equivocal database, respectively. Conclusion. Computerized analysis of US images has the potential to increase the specificity of breast sonography.