Diffusion-weighted Imaging of Breast Cancer with the Sensitivity Encoding Technique: Analysis of the Apparent Diffusion Coefficient Value

Differentiation between benign and malignant breast lesions using quantitative diffusion-weighted sequence on 3 T MRI

AIM

To investigate the capability and diagnostic accuracy of diffusion-weighted imaging (DWI) in differentiating benign from malignant breast lesions using 3 T magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Women with suspicious or indeterminate breast lesions detected at MRI, mammogram and/or ultrasound were recruited for dynamic contrast-enhanced (DCE)-MRI and DWI prior to their biopsy. Image fusion of DCE-MRI with apparent diffusion coefficient (ADC) map was utilized to select the region of interest (ROI) for ADC calculation in the area that showed the most avid enhancement. DWI was performed using two sets of b-values at 500 and 1000 s/mm(2), respectively.

RESULTS

Fifty women were recruited and the final analysis comprised 44 breast lesions, 31 of which were malignant and 13 were benign. Significant results were obtained between ADC values of benign and malignant lesions (p < 0.001). The cut-off ADC values for benign and malignant lesions were 1.21 × 10(-3) mm(2)/s for b = 500 s/mm(2) and 1.22 × 10(-3) mm(2)/s for b = 1000 s/mm(2), respectively. The sensitivity of DCE-MRI alone was 100% with a specificity of 66.7%. When DCE-MRI was combined with b = 1000 s/mm(2), the specificity rose to 100%, while only mildly affecting sensitivity (90.6%). No significant correlation was found between ADC values and prognostic factors, such as lymph node metastasis, tumour size, oestrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status, and tumour grades.

CONCLUSION

The present study provides consistent evidence to support DWI as a diagnostic tool for breast lesion characterization. A combination of DCE-MRI with DWI is suggested to improve the sensitivity and specificity of lesion characterization.

Diffusion-weighted imaging of the breast: comparison of b-values 1000 s/mm² and 1500 s/mm²

PURPOSE

We compared diffusion-weighted imaging (DWI) of the breast using 2 different b-values to determine the optimal b-value for greatest signal contrast between tumors and normal tissue of the breast.

MATERIALS AND METHODS

We performed DWI of the breast at b-values of 1000 s/mm(2) and 1500 s/mm(2) in 120 patients (121 lesions, 19 benign, 102 malignant) and visually scored image quality with regard to artifact and visibility of tumors. We quantitatively evaluated the signal-to-noise ratio (SNR) of the tumor and contrast-to-noise ratio (CNR) and contrast ratio (CR) between the tumor and normal breast parenchyma.

RESULTS

The CR of invasive carcinoma (IC), ductal carcinoma in situ (DCIS), and benign tumors significantly improved with b=1500 s/mm(2) compared with b=1000 s/mm(2). The SNR and CNR were significantly lower with b=1500 s/mm(2) than b=1000 s/mm(2) despite the increasing number of excitations at b=1500 s/mm(2). At b=1500 s/mm(2), the difference in SNR, CNR, and CR between IC and DCIS and benign tumors was statistically significant.

CONCLUSION

DWI may depict breast tumors more clearly with b=1500 s/mm(2) than b=1000 s/mm(2).

MR imaging of malignant primary breast lymphoma: including diffusion-weighted imaging, histologic features, and a literature review

OBJECTIVE

To investigate the magnetic resonance (MR) imaging characteristics of malignant primary breast lymphoma (PBL), including features on diffusion-weighted imaging (DWI).

METHODS

The MR findings of three patients were reviewed retrospectively at our institutions. The signal intensity, shape, enhancement pattern, and DWI findings were examined and correlated with the histologic features. We also reviewed the MR findings of cases of PBL reported in the literature.

RESULTS

The tumors in our cases showed early enhancement with penetrating vessels on early-phase dynamic MR images and a strong high signal intensity on DWI. The tumors had a cerebroid appearance and septal enhancement on delayed contrast-enhanced MR images, and we speculate that the fibrous tissue seen in the tumors may correspond to septal enhancement. After chemotherapy, all lesions decreased in size, while the ADCs were increased. All of the cases reported in the literature showed early or avid enhancement; this finding was similar to that observed in our cases.

CONCLUSIONS

Although based on a small number of cases, we suggest that strong enhancement with penetrating vessels in masses on early images of dynamic MR, strong high intensity on DWI, a cerebroid appearance, and septal enhancement are useful diagnostic clues for a diagnosis of PBL.

Magnetic resonance in the detection of breast cancers of different histological types

Breast cancer incidence is increasing worldwide. Early detection is critical for long-term patient survival, as is monitoring responses to chemotherapy for management of the disease. Magnetic resonance imaging and spectroscopy (MRI/MRS) has gained in importance in the last decade for the diagnosis and monitoring of breast cancer therapy. The sensitivity of MRI/MRS for anatomical delineation is very high and the consensus is that MRI is more sensitive in detection than x-ray mammography. Advantages of MRS include delivery of biochemical information about tumor metabolism, which can potentially assist in the staging of cancers and monitoring responses to treatment. The roles of MRS and MRI in screening and monitoring responses to treatment of breast cancer are reviewed here. We rationalize how it is that different histological types of breast cancer are differentially detected and characterized by MR methods.

Ultra high spatial and temporal resolution breast imaging at 7T

There is a need to obtain higher specificity in the detection of breast lesions using MRI. To address this need, Dynamic Contrast-Enhanced (DCE) MRI has been combined with other structural and functional MRI techniques. Unfortunately, owing to time constraints structural images at ultra-high spatial resolution can generally not be obtained during contrast uptake, whereas the relatively low spatial resolution of functional imaging (e.g. diffusion and perfusion) limits the detection of small lesions. To be able to increase spatial as well as temporal resolution simultaneously, the sensitivity of MR detection needs to increase as well as the ability to effectively accelerate the acquisition. The required gain in signal-to-noise ratio (SNR) can be obtained at 7T, whereas acceleration can be obtained with high-density receiver coil arrays. In this case, morphological imaging can be merged with DCE-MRI, and other functional techniques can be obtained at higher spatial resolution, and with less distortion [e.g. Diffusion Weighted Imaging (DWI)]. To test the feasibility of this concept, we developed a unilateral breast coil for 7T. It comprises a volume optimized dual-channel transmit coil combined with a 30-channel receive array coil. The high density of small coil elements enabled efficient acceleration in any direction to acquire ultra high spatial resolution MRI of close to 0.6 mm isotropic detail within a temporal resolution of 69 s, high spatial resolution MRI of 1.5 mm isotropic within an ultra high temporal resolution of 6.7 s and low distortion DWI at 7T, all validated in phantoms, healthy volunteers and a patient with a lesion in the right breast classified as Breast Imaging Reporting and Data System (BI-RADS) IV.

The usefulness of diffusion-weighted imaging in the characterization of liver lesions in patients with cirrhosis

AIM

To evaluate if diffusion-weighted imaging (DWI) is useful in characterizing liver lesions in patients with cirrhosis.

MATERIALS AND METHODS

A retrospective review revealed 37 patients with cirrhosis who had 41 histologically proven hepatocellular carcinoma (HCC) lesions. Another 20 patents with cirrhosis had 29 solid nodules that remained stable for at least 12 months and were deemed to be benign hepatic nodules (BHN). Of the HCC lesions, 14 were well-differentiated (WD HCC), 20 were moderately differentiated, and seven were poorly differentiated histology. For all lesions, two reviewers analysed signal characteristics and made apparent diffusion coefficient value (ADC) measurements.

RESULTS

Visual analysis of DWI was useful in that no HCC was hypointense and no BHN was hyperintense to liver. Visual analysis of DWI was not useful in separating WD HCC from higher grades. There was substantial overlap in ADC values of the HCC and BHN. Among HCC lesions, ADC values of more than 0.99 × 10(-3) mm(2)/s had sensitivity and specificity of 85% and 86% for reviewer 1, and 63% and 64% for reviewer 2 in diagnosing WD HCC.

CONCLUSIONS

ADC measurements of BHN were higher than that of HCC, and the ADC values of WD HCC were higher than that of more aggressive grades of HCC. However, quantitative measurements may not help in determining the histological grade of individual cases of HCC.

Diffusion tensor magnetic resonance imaging of the normal breast: reproducibility of DTI-derived fractional anisotropy and apparent diffusion coefficient at 3.0 T

PURPOSE

Diffusion-weighted imaging (DWI) may improve the diagnostic performance of conventional breast magnetic resonance imaging (MRI). Diffusion tensor imaging (DTI) is an extension of DWI. If DTI-derived measurements are to be clinically useful, particularly for predicting and/or monitoring therapeutic effects, they must be robust and reliable. The purpose of this study was to assess intra- and interobserver reproducibility of DTI-derived fractional anisotropy (FA) and apparent diffusion coefficient (ADC) at 3.0 T.

MATERIALS AND METHODS

This prospective study was approved by the Institutional Review Board, and participants provided written informed consent. Sixty normal contralateral breasts of 60 patients (28-85 years, median 57) were analysed with a DWI sequence following a standard MRI protocol. Four authors performed all postprocessing and analyses independently and in different sessions. The same authors, blinded to the initial results, repeated the image postprocessing and analysis 4 weeks after the initial session.

RESULTS

Mean ADC and FA for DTI sequences were, respectively, 1.92±0.30 and 0.32±0.09. Intra- and interobserver agreement of the four radiologists for ADC and FA were good (acceptable). Kappa values for ADC were intra-R1=0.82; intra-R2=0.84; intra-R3=0.89; intra-R4=0.88; inter-R1-R2=0.73; inter-R1-R3=0.74; inter-R1-R4=0.81; inter-R2-R3=0.76; inter-R2-R4=0.77; inter-R3-R4=0.83. Kappa values for FA were intra-R1=0.60; intra-R2=0.72; intra-R3=0.84; intra-R4 = 0.66; inter-R1-R2=0.64; inter-R1-R3=0.69; inter-R1-R4=0.72; inter-R2-R3=0.80; inter-R2-R4=0.71; inter-R3-R4=0.73. Within-subject coefficient of variation was 15% for ADC and 30% for FA. Repeatability with α=0.05 was 0.37×10-3 mm(2)/s for ADC and 0.112 for FA.

CONCLUSIONS

ADC and FA measurements obtained with DTI are reproducible and may be valid, reliable and sensitive to change. ADC values obtained with DTI are more reproducible than FA.

[Influence of b value on the measurement of contrast and apparent diffusion coefficient in 3.0 Tesla breast magnetic resonance imaging]

Diffusion-weighted imaging (DWI) has been used to characterize not only the brain, but also the breast by implementation of faster imaging techniques and higher magnetic field strengths. However, the optimum b value, which is an important scan parameter for DW images contrast on 3 T breast magnetic resonance imaging (MRI) has not been established. The purpose of this study was to investigate the influence of different b value combinations on the image contrast and apparent diffusion coefficient (ADC) in patients with known invasive carcinoma, ductal carcinoma in situ (DCIS), and normal mammary gland in breast DWI. The analysis procedure consisted of the following methods: 1) T(2) correction of DW images with echo-planar imaging (EPI) T(2)-weighted images; 2) contrast measurement between normal mammary gland and tumor tissues; 3) ADC measurement of normal mammary gland and tumor tissues. In many cases, the highest contrast between normal mammary gland and tumor tissues was obtained using a b value of 1500 s/mm(2). Our results indicated that when only one b value is used, the b value in which signal intensities of normal mammary gland decreases down to noise level, and the contrast between normal mammary gland and tumor tissues is recommended. ADC value decreased with increasing b value. Therefore, when determining the ADC threshold level, it is important to perform the evaluation using ADC values calculated from DW images with the same b value in clinical studies.

Conspicuity of breast lesions at different b values on diffusion-weighted imaging

Background

Diffusion-weighted (DW) imaging has shown potential to differentiate between malignant and benign breast lesions. However, different b values have been used with varied sensitivity and specificity. This study aims to prospectively evaluate the influence of b value on the detection and assessment of breast lesions.

Methods

Institutional review board approval and informed patient consent were obtained. Between February 2010 and September 2010, sixty women suspected of having breast cancer by clinical examination and mammography underwent bilateral breast MRI and DW imaging (with maximum b values of 600, 800, and 1000 s/mm²). Conspicuity grades of lesions at different b values on DW images were performed. Signal intensity and apparent diffusion coefficient (ADC) values were recorded and compared among different b values by the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and receiver operating characteristic (ROC) curve.

Results

Fifty-seven lesions from 52 recruited patients including 39/57 (68%) malignant and 18/57 (32%) benign were confirmed with pathology. DCE MRI accurately detected 53 lesions with the sensitivity of 93.0% and specificity of 66.7%, and DW imaging accurately detected 51 lesions with the sensitivity of 89.5% and specificity of 100%. There were no significant differences in conspicuity grades compared among the three b values (P = 0.072), although the SNR and CNR of breast lesions decreased significantly with higher b values. Mean ADCs of malignant lesions (b = 600 s/mm², 1.07 ± 0.26 × 10^-3 mm²/s; b = 800 s/mm², 0.96 ± 0.22 × 10^-3 mm²/s; b = 1000 s/mm², 0.92 ± 0.26 × 10^-3 mm²/s) were significantly lower than those of benign lesions (b = 600 s/mm², 1.55 ± 0.40 × 10^-3 mm²/s; b = 800 s/mm², 1.43 ± 0.38 × 10^-3 mm²/s; b = 1000 s/mm², 1.49 ± 0.38 × 10^-3 mm²/s) with all P values <0.001, but there were no significant differences among the three b values (P = 0.303 and 0.840 for malignant and benign lesions, respectively). According to the area under the ROC curves, which were derived from ADC and differentiate malignant from benign lesions, no significant differences were found among the three b values (P = 0.743).

Conclusions

DW imaging is a potential adjunct to conventional MRI in the differentiation between malignant and benign breast lesions. Varying the maximum b value from 600 to 1000 s/mm² does not influence the conspicuity of breast lesions on DW imaging at 1.5 T.

Correlation of the apparent diffusion coefficiency values on diffusion-weighted imaging with prognostic factors for breast cancer

OBJECTIVE

The aim of this study was to correlate the apparent diffusion coefficient (ADC) value of breast cancer with prognostic factors.

METHODS

335 patients with invasive ductal carcinoma not otherwise specified (IDC NOS) and ductal carcinoma in situ (DCIS) who underwent breast MRI with diffusion-weighted imaging were included in this study. ADC of breast cancer was calculated using two b factors (0 and 1000 s mm(-2)). Mean ADCs of IDC NOS and DCIS were compared and evaluated. Among cases of IDC NOS, mean ADCs were compared with lymph node status, size and immunochemical prognostic factors using Student's t-test. ADC was also correlated with histological grade using the Kruskal-Wallis test.

RESULTS

Mean ADC of IDC NOS was significantly lower than that of DCIS (p<0.001). However, the mean ADC of histological grade of IDC NOS was not significantly different (p=0.564). Mean ADC of oestrogen receptor (ER)-positive or progesterone receptor (PR)-positive cancer was significantly lower than that of ER-negative or PR-negative cancer (p=0.003 vs p=0.032). Mean ADC of Ki-67 index-positive cancer was significantly lower than that of Ki-67 index-negative cancer (p=0.028). Mean ADC values of cancers with increased microvascular density (MVD) were significantly lower than those of cancer with no MVD increase (p=0.009). No correlations were observed between mean ADC value and human growth factor receptor 2 expression, tumour size and lymph node metastasis.

CONCLUSION

Low ADC value was correlated with positive expression of ER, PR, increased Ki-67 index, and increased MVD of breast cancer.

Molecular imaging of water binding state and diffusion in breast cancer using diffuse optical spectroscopy and diffusion weighted MRI

Tissue water content and molecular microenvironment can provide important intrinsic contrast for cancer imaging. In this work, we examine the relationship between water optical spectroscopic features related to binding state and magnetic resonance imaging (MRI)-measured water diffusion dynamics. Broadband diffuse optical spectroscopic imaging (DOSI) and MR images were obtained from eight patients with locally-advanced infiltrating ductal carcinomas (tumor size=5.5 ± 3.2 cm). A DOSI-derived bound water index (BWI) was compared to the apparent diffusion coefficient (ADC) of diffusion weighted (DW) MRI. BWI and ADC were positively correlated (R=0.90, p-value=0.003) and BWI and ADC both decreased as the bulk water content increased (R=-0.81 and -0.89, respectively). BWI correlated inversely with tumor size (R=-0.85, p-value=0.008). Our results suggest underlying sensitivity differences between BWI and ADC to water in different tissue compartments (e.g., extracellular vs cellular). These data highlight the potential complementary role of DOSI and DW-MRI in providing detailed information on the molecular disposition of water in breast tumors. Because DOSI is a portable technology that can be used at the bedside, BWI may provide a low-cost measure of tissue water properties related to breast cancer biology.

Apparent diffusion coefficient measurements in the differentiation between benign and malignant lesions: a systematic review

Objectives

To systematically review the value of apparent diffusion coefficient (ADC) measurement in the differentiation between benign and malignant lesions.

Methods

A systematic search of the Medline/Pubmed and Embase databases revealed 109 relevant studies. Quality of these articles was assessed using the Quality Assessment of the Studies of Diagnostic Accuracy Included in Systematic Reviews (QUADAS) criteria. Reported ADC values of benign and malignant lesions were compared per organ.

Results

The mean quality score of the reviewed articles was 50%. Comparison of ADC values showed marked variation among studies and between benign and malignant lesions in various organs. In several organs, such as breast, liver, and uterus, ADC values discriminated well between benign and malignant lesions. In other organs, such as the salivary glands, thyroid, and pancreas, ADCs were not significantly different between benign and malignant lesions.

Conclusion

The potential utility of ADC measurement for the characterisation of tumours differs per organ. Future well-designed studies are required before ADC measurements can be recommended for the differentiation of benign and malignant lesions. These future studies should use standardised acquisition protocols and provide complete reporting of study methods, to facilitate comparison of results and clinical implementation of ADC measurement for tumour characterisation.

Electronic supplementary material

The online version of this article (doi:10.1007/s13244-012-0175-y) contains supplementary material, which is available to authorized users.

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.

High-resolution diffusion-weighted magnetic resonance imaging in patients with locally advanced breast cancer

RATIONALE AND OBJECTIVES

The aim of this study was to evaluate differences in tumor depiction and measured tumor apparent diffusion coefficient (ADC) with the use of a high-resolution diffusion-weighted (DW) magnetic resonance imaging (MRI) sequence, compared to a standard DW MRI sequence, in patients with locally advanced breast cancer.

MATERIALS AND METHODS

Patients with locally advanced breast cancer were scanned with a reduced-field of view (rFOV) DW MRI sequence (high resolution) and a standard-field of view diffusion sequence (standard resolution), and differences between the two sequences were evaluated quantitatively (by calculating tumor ADC distribution parameters) and qualitatively (by radiologists' visual assessments of images).

RESULTS

Although the mean tumor ADC for both sequences was similar, differences were found in other parameters, including the 12.5th percentile (P = .042) and minimum tumor ADC (P = .003). Qualitatively, visualization of tumor morphologic detail, heterogeneity, and conspicuity was improved with rFOV DW MRI, and image quality was higher.

CONCLUSIONS

Differences in ADC distribution parameters and qualitative image features suggest that the sequences differ in their ability to capture tumor heterogeneity. These differences are not apparent when the mean is used to evaluate tumor ADC. In particular, differences found in lower ADC values are compatible with reduced partial voluming in rFOV DW MRI, suggesting that rFOV DW MRI may be valuable in imaging the lower ADCs expected to correspond to viable tumor in most invasive breast cancers.

Histological grade of differentiation of hepatocellular carcinoma: comparison of the efficacy of diffusion-weighted MRI with T2-weighted imaging and angiography-assisted CT

INTRODUCTION

The purpose of this study is to determine the usefulness of diffusion-weighted imaging (DWI) for evaluating the histological grade of differentiation of hepatocellular carcinoma (HCC) compared with T2-weighted imaging (T2WI) and tumour haemodynamics.

METHODS

We retrospectively evaluated 32 patients with 42 pathologically confirmed HCC nodules. These patients underwent MRI, CT during arterial portography and CT hepatic arteriography. We evaluated the relationship between the histological grade of differentiation and the apparent diffusion coefficient (ADC) values, conspicuity of tumour on DWI, DWI and T2WI contrast-to-noise (C/N) ratios and tumour haemodynamics.

RESULTS

There was no correlation between the histological grade of differentiation and the ADC values. The DWI C/N ratio was significantly different among all histological grades, but the T2WI C/N ratio was not. Tumour conspicuity on DWI correlated well with the histological grade of differentiation, but tumour haemodynamics only partially correlated with the histological grade of differentiation.

CONCLUSION

DWI was useful for evaluating the histological grade of differentiation of HCC.

Tumour response prediction by diffusion-weighted MR imaging: ready for clinical use?

BACKGROUND

The efficacy of anticancer therapy is usually evaluated by anatomical imaging. However, this method may be suboptimal for the evaluation of novel treatment modalities, such as targeted therapy. Theoretically, functional assessment of tumour response by diffusion weighted imaging (DWI) is an attractive tool for this purpose and may allow an early prediction of response. The optimal use of this method has still to be determined.

METHOD

We reviewed the published literature on clinical DWI in the prediction of response to anticancer therapy, especially targeted therapy. Studies investigating the role of DWI in patients with cancer either for response prediction and/or response monitoring were selected for this analysis.

RESULTS

We identified 24 studies that met our criteria. Most studies showed a significant correlation between (changes in) apparent diffusion coefficient (ADC) values and treatment response. However, in different tumours and studies, both high and low pretreatment ADC were found to be associated with response rate. In the course of treatment, an increase in ADC was associated with response in most cases.

CONCLUSION

The potential of DWI for (early) response monitoring of anticancer therapies has been demonstrated. However, validation is hampered by the lack of reproducibility and standardisation. We recommend that these issues should be properly addressed prior to further testing the clinical use of DWI in the assessment of treatments.

Diffusion-weighted imaging findings of mucinous carcinoma arising in the ano-rectal region: comparison of apparent diffusion coefficient with that of tubular adenocarcinoma

PURPOSE

To determine the diffusion-weighted imaging (DWI) characteristics of ano-rectal mucinous carcinoma. Apparent diffusion coefficient (ADC) and DWI findings for mucinous and tubular adenocarcinomas were retrospectively compared.

MATERIALS AND METHODS

Eight-one consecutive surgically resected ano-rectal adenocarcinomas were evaluated. The patient group consisted of 15 mucinous and 66 tubular adenocarcinomas. The DWI signal intensity (SI) pattern of each tumor was visually classified into one of three groups. Differences in the proportions in each group were statistically compared for the two types of tumor. The ADCs of each tumor, calculated from two different b-factors (0 and 1500 s/mm(2)) were compared statistically.

RESULTS

Visual evaluation revealed ten mucinous carcinomas as predominantly hypointense lesions, and the remaining five as mixed SI lesions. Sixty-one of 66 tubular adenocarcinomas had hyperintensities; the remaining five had mixed SI. The different proportions in each group were statistically significant. The mean ADC for mucinous carcinomas was 1.49 ± 0.34 × 10(-3) mm(2)/s whereas that for tubular adenocarcinomas was 0.80 ± 0.15 × 10(-3) mm(2)/s. The difference between those figures was statistically significant.

CONCLUSION

In DWI, mucinous carcinomas had higher ADCs and lower SI than tubular adenocarcinomas. DWI and ADC measurements were useful for differentiating these two tumors.

Comparisons of multi b-value DWI signal analysis with pathological specimen of breast cancer

Previous studies have reported that the signal attenuation of diffusion weighted magnetic resonance imaging for tumor tissues displays a non-monoexponential biexponential decay, and the apparent diffusion coefficients (ADCs) can be divided into a fast and slow diffusion component by using a simple biexponential decay model. The purpose of this study is to examine the non-monoexponential character of the diffusion weighted magnetic resonance imaging signal attenuations of breast cancers, estimate the fast and slow diffusion components, and compare them with the extra- and intracellular component information obtained from the pathological specimens. Twenty-two subjects having breast cancers underwent diffusion weighted magnetic resonance imaging using six b-values up to 3500 s/mm(2) and the signal attenuations were analyzed using the biexponential function. The derived slow component fraction correlated with the cellular fraction and the ADCs converged to 0.2-0.3 × 10(-3) mm(2) /s for the higher cellular fractions. The ADCs of the fast component ranged from 1.3 to 3.9 × 10(-3) mm(2) /s and showed no correlation with the extracellular components. This result suggests that the main reason for the decreasing ADC of a breast tumor is the decreasing fraction of the fast component and the increasing fraction of the slow component having a low ADC rather than the decreasing ADC of the fast component by the restricted water diffusion in the reduced extracellular spaces.

Emerging techniques and molecular imaging in breast cancer

The sensitivity of screening mammography is limited in the evaluation of dense breasts, with as few as 45% of cancers visible in extremely dense breasts. Supplementary imaging for improved sensitivity in women with dense breasts is necessary to overcome this limitation. Emerging technologies that advance the applications of digital mammography include digital breast tomosynthesis and dedicated breast cone-beam computed tomography. Molecular imaging goes beyond structural imaging. A functional imaging technique that provides information on the biology, physiology, and metabolic pathways of cancer might help to improve the sensitivity and specificity of breast cancer diagnosis, facilitate early assessment of treatment response, and help individualize therapy options for patients. Advanced magnetic resonance, nuclear medicine, and optical imaging techniques in the realm of molecular imaging will be explored in this article.

Usefulness of diffusion-weighted imaging of breast tumors: quantitative and visual assessment

PURPOSE

We evaluated the usefulness of quantitative and visual assessment of diffusion-weighted imaging (DWI) of breast tumors to distinguish malignant from benign tumors.

MATERIALS AND METHODS

The DWI findings of 106 breast lesions (15 benign, 91 malignant) were retrospectively analyzed. The mean apparent diffusion coefficient (ADC) value for each lesion was calculated using b values of 250, 500, 750, and 1000 s/mm(2) as a quantitative assessment. We visually evaluated the signal intensity of each breast lesion on the basis of a spinal signal intensity in DWI (b = 1000 s/mm(2)) and compared the mean ADC values using a threshold mean ADC +1.65 × standard deviation (SD) for malignant and benign breast lesions. Obviously strong signal intensity of the lesion relative to that of the spinal cord on DWI signifies malignancy.

RESULTS

The mean ADC value for benign lesions (1.50 ± 0.38 × 10(-3) mm(2)/s) was significantly higher than that for malignant lesions (0.98 ± 0.19 × 10(-3) mm(2)/s), with 94.5% sensitivity, 80% specificity, and 92.5% accuracy. Sensitivity for visual assessment was 91.5%, specificity was 33.3%, and total accuracy was 82.5%.

CONCLUSION

ADC values, but not visual assessment, may be useful for differentiating benign and malignant breast tumors.

Breast MR with special focus on DW-MRI and DCE-MRI

The use of magnetic resonance imaging (MRI) for the assessment of breast lesions was first described in the 1970s; however, its wide application in clinical routine is relatively recent. The basic principles for diagnosis of a breast lesion rely on the evaluation of signal intensity in T2-weighted sequences, on morphologic assessment and on the evaluation of contrast enhancement behaviour. The quantification of dynamic contrast behaviour by dynamic contrast-enhanced (DCE) MRI and evaluation of the diffusivity of water molecules by means of diffusion-weighted MRI (DW-MRI) have shown promise in the work-up of breast lesions. Therefore, breast MRI has gained a role for all indications that could benefit from its high sensitivity, such as detection of multifocal lesions, detection of contralateral carcinoma and in patients with familial disposition. Breast MRI has been shown to have a role in monitoring of neoadjuvant chemotherapy, for the evaluation of therapeutic results during the course of therapy. Breast MRI can improve the determination of the remaining tumour size at the end of therapy in patients with a minor response. DCE-MRI and DW-MRI have shown potential for improving the early assessment of tumour response to therapy and the assessment of residual tumour after the end of therapy. Breast MRI is important in the postoperative work-up of breast cancers. High sensitivity and specificity have been reported for the diagnosis of recurrence; however, pitfalls such as liponecrosis and changes after radiation therapy have to be carefully considered.

Improved hardware for higher spatial resolution strain-encoded (SENC) breast MRI for strain measurements

RATIONALE AND OBJECTIVES

Early detection of breast lesions using mammography has resulted in lower mortality rates. However, some breast lesions are mammography occult, and magnetic resonance imaging (MRI) is recommended, but it has lower specificity. It is possible to achieve higher specificity by using strain-encoded (SENC) MRI and/or magnetic resonance elastography. SENC breast MRI can measure the strain properties of breast tissue. Similarly, magnetic resonance elastography is used to measure the elasticity (ie, shear stiffness) of different tissue compositions interrogating the tissue mechanical properties. Reports have shown that malignant tumors are three to 13 times stiffer than normal tissue and benign tumors.

MATERIALS AND METHODS

The investigators have developed a SENC breast hardware device capable of periodically compressing the breast, thus allowing for longer scanning time and measuring the strain characteristics of breast tissue. This hardware enables the use of SENC MRI with high spatial resolution (1 × 1 × 5 mm(3)) instead of fast SENC imaging. Simple controls and multiple safety measures were added to ensure accurate, repeatable, and safe in vivo experiments.

RESULTS

Phantom experiments showed that SENC breast MRI has higher signal-to-noise ratio and contrast-to-noise ratio than fast SENC imaging under different scanning resolutions. Finally, the SENC breast device reproducibility measurements resulted in a difference of <1 mm with a 1% strain difference.

CONCLUSIONS

SENC breast magnetic resonance images have higher signal-to-noise ratio and contrast-to-noise ratios than fast SENC images. Thus, combining SENC breast strain measurements with diagnostic breast MRI to differentiate benign from malignant lesions could potentially increase the specificity of diagnosis in the clinical setting.

Characterization of ductal carcinoma in situ on diffusion weighted breast MRI

OBJECTIVES

To characterize ductal carcinoma in situ (DCIS) and its subtypes on diffusion-weighted imaging (DWI).

METHODS

We retrospectively reviewed 74 pure DCIS lesions in 69 women who underwent DWI at 1.5 T (b = 0 and 600 s/mm(2)). Each lesion was characterized by qualitative DWI intensity, quantitative DWI lesion-to-normal contrast-to-noise ratio (CNR), and quantitative apparent diffusion coefficient (ADC). The detection rate was calculated with predetermined thresholds for each parameter. The effects of lesion size, grade, morphology, and necrosis were assessed.

RESULTS

Ninety-six percent (71/74) of DCIS lesions demonstrated greater qualitative DWI intensity than normal breast tissue. Quantitatively, DCIS lesions demonstrated on average 56% greater signal than normal tissue (mean CNR = 1.83  ±  2.7) and lower ADC values (1.50 ± 0.28 × 10(-3) mm(2)/s) than normal tissue (2.01 ± 0.37 × 10(-3) mm(2)/s, p < 0.0001). A 91% detection rate was achieved utilizing an ADC threshold (<1.81 × 10(-3) mm(2)/s ). Non-high-grade DCIS exhibited greater qualitative DWI intensity (p = 0.02) and quantitative CNR (p = 0.01) than high-grade DCIS but no difference in ADC (p = 0.40). Lesion size, morphology, and necrosis did not affect qualitative or quantitative DWI parameters of DCIS lesions (p > 0.05).

CONCLUSIONS

DCIS lesions have higher DWI signal intensity and lower ADC values than normal breast tissue. DWI warrants further investigation as a potential non-contrast MRI tool for early breast cancer detection.

Predictive value for malignancy of suspicious breast masses of BI-RADS categories 4 and 5 using ultrasound elastography and MR diffusion-weighted imaging

OBJECTIVE

The aim of this study is to evaluate the ability of ultrasound elastography and MR diffusion-weighted imaging (DWI) to predict malignancy of breast masses, with subsequent recommendation for biopsy.

MATERIALS AND METHODS

For 115 breast masses classified as BI-RADS category 4 or 5, which were assessed according to combined findings of mammography, B-mode sonography, and dynamic contrast-enhanced MRI, two radiologists retrospectively evaluated the elasticity scores using ultrasound elastography and the apparent diffusion coefficient (ADC) values using MR DWI. The diagnostic abilities of these two techniques were analyzed by using univariate and multivariate logistic regression analysis.

RESULTS

In the analysis of all 115 breast masses, the elasticity score was predictive of malignancy, whereas the ADC value was not independently predictive. In an analysis of the 52 masses assessed as BI-RADS category 4, the elasticity score was found to be a significant predictor of malignancy, compared with the ADC value, which was a nonsignificant predictor. In an analysis of the 63 masses assessed as BI-RADS category 5, neither the elasticity score nor the ADC value was a significant predictor of malignancy.

CONCLUSION

Our results show that elasticity imaging provides relatively reliable predictions for malignancy, especially in BI-RADS category 4 masses, compared with MR DWI.

Contribution of diffusion-weighted imaging to dynamic contrast-enhanced MRI in the characterization of breast tumors

OBJECTIVE

The purpose of our study was to evaluate the diagnostic value of an imaging protocol that combines dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted imaging (DWI) in patients with suspicious breast lesions and to determine if additional information provided by DWI improves the diagnostic value of breast MRI.

MATERIALS AND METHODS

Eighty-four patients with breast tumors (37 benign, 47 malignant) underwent DCE-MRI and DWI before biopsy. Morphologic and kinetic analyses were performed on DCE-MRI and findings were classified according to the BI-RADS lexicon. Apparent diffusion coefficient (ADC) values were calculated from the DWI. The ADCs of the benign and malignant lesions were compared. For the combined MRI protocol, morphologic kinetic features and ADCs were evaluated together. Diagnostic values of DCE-MRI, DWI, and combined MRI were calculated.

RESULTS

Median ADCs of the benign and malignant lesions were 1.26 × 10(-3) mm(2)/s and 0.75 × 10(-3) mm(2)/s, respectively. Cutoff value of 0.92 × 10(-3) mm(2)/s for ADC provided 91.5% sensitivity and 86.5% specificity. DCE-MRI alone showed 97.9% sensitivity and 75.7% specificity. The combination of DCE-MRI with DWI provided 95.7% sensitivity and 89.2% specificity. The specificity of breast MRI improved by 13.5% (p = 0.063) without a significant decrease in the sensitivity (p = 1.000).

CONCLUSION

The combination of DWI and DCE-MRI has the potential to increase the specificity of breast MRI.

Radiologic-pathologic correlation of ductal carcinoma in situ

Ductal carcinoma in situ (DCIS) accounts for 20%-25% of breast cancers detected at screening mammography. The lesions are diverse and commonly are classified on the basis of their mammographic features and histologic characteristics such as nuclear grade and presence or absence of necrosis. The most common mammographic finding in DCIS is microcalcifications, but a low-grade lesion without necrosis is less likely to manifest with calcifications than either an intermediate- or a high-grade lesion. Other mammographic findings might include a mass or architectural distortion. Magnetic resonance (MR) imaging has higher sensitivity than mammography for the detection of DCIS and greater accuracy for depicting the extent of disease. The MR imaging appearance of DCIS depends primarily on the presence and extent of abnormal periductal or stromal vascularity. Nonmasslike enhancement, the most common MR imaging finding, is often seen in association with clumped internal enhancement. The enhancement kinetics in dynamic MR studies vary, and no kinetic pattern is pathognomonic of a particular nuclear grade of DCIS. However, the kinetic pattern at delayed imaging does appear to be correlated with the mammographic findings: Mass lesions show strong washout; fine pleomorphic, fine linear, and fine linear-branching calcifications demonstrate a plateau enhancement pattern; and amorphous calcifications exhibit persistent enhancement. Multidetector computed tomography might be a useful adjunct to MR imaging for preoperative mapping.

Meta-analysis of quantitative diffusion-weighted MR imaging in the differential diagnosis of breast lesions

Background

To determine, in a meta-analysis, the diagnostic performance of quantitative diffusion-weighted (DW) MR imaging in patients with breast lesions.

Methods

English and Chinese studies published prior to June 2009 to assess the diagnostic performance of quantitative DWI in patients with breast lesions were reviewed and summarized with reference to the inclusion and exclusion criteria. Methodological quality was assessed by using the quality assessment of diagnostic studies (QUADAS) instrument. Publication bias analysis was performed by using Comprehensive Meta-analysis version 2. Meta-Disc version 1.4 was used to describe primary results and explore homogeneity by Chi-square test and inconsistency index; to explore threshold effect by receiver operator characteristic (ROC) space and Spearman correlation coefficient; and to pool weighted sensitivity and specificity by fixed or random effect model. A summary ROC (sROC) curve was constructed to calculate the area under the curve (AUC).

Results

Of 65 eligible studies, 13 with 615 malignant and 349 benign lesions were included in the original meta-analysis, among which heterogeneity arising from factors other than threshold effect and publication bias was explored. Methodological quality was moderate. The pooled weighted sensitivity and specificity with corresponding 95% confidence interval (CI) in one homogenous subgroup of studies using maximum b = 1000 s/mm² were 0.84 (0.80, 0.87) and 0.84 (0.79, 0.88) respectively. AUC of sROC was 0.9085. Sensitivity analysis demonstrated that the pooled estimates were stable and reliable.

Conclusions

Quantitative DWI has a higher specificity to differentiate between benign and malignant breast lesions compared to that of contrast-enhanced MRI. However, large scale randomized control trials (RCTs) are necessary to assess its clinical value because of disunified diffusion gradient factor b and diagnosis threshold.

Breast MR imaging: current indications and advanced imaging techniques

Breast cancer is the most common solid tumor diagnosed in women. In the past decades, great strides have been made in breast cancer screening. While multiple screening trials have shown the benefits of screening mammography, there are limitations to x-ray mammography. Given these inherent limitations, efforts have been made to develop adjunctive imaging techniques, including screening ultrasonography, gamma-specific breast imaging, breast tomosynthesis, dedicated breast computed tomography, and breast magnetic resonance (MR) imaging. This article addresses the current indications and advanced imaging applications of breast MR imaging.

Diffusion-weighted imaging in breast cancer: relationship between apparent diffusion coefficient and tumour aggressiveness

AIM

To assess the utility of diffusion-weighted imaging in diagnosing and characterizing breast malignancy.

MATERIALS AND METHODS

From April 2006 to April 2009, all consecutive patients with breast cancer undergoing breast magnetic resonance imaging (MRI) and subsequent surgery in our hospital were enrolled in this study. MRI was performed using a 1.5 T MRI unit using a dedicated, bilateral, four-channel breast coil. The MRI protocol included a diffusion sequence acquired using b values of 0 and 1000 s/mm(2). For each malignant lesion the relationships between tumour grade and histology and the relative value of the apparent diffusion coefficient (ADC) were analysed.

RESULTS

There were 136 female patients with 162 lesions. Histology revealed 149 invasive carcinomas and 13 ductal carcinomas in situ. There were 34 grade 1, 61 grade 2, and 67 grade 3 lesions. The mean ADC value of all malignant lesions was 1.03×10(-3) mm(2)/s. The mean ADC values for invasive and in situ carcinomas were 1.03×10(-3) mm(2)/s and 1.05×10(-3) mm(2)/s, respectively. The mean ADC values for grade 1, 2, and 3 tumours were 1.25×10(-3) mm(2)/s, 1.02×10(-3) mm(2)/s, and 0.92×10(-3) mm(2)/s, respectively. A statistically significant (p<0.001) inverse correlation was disclosed between the ADC value and the tumour grading. The mean ADC value of the "less aggressive" group of disease (G1 and in situ lesions) was 1.19×10(-3) mm(2)/s, whereas the mean ADC value of the "more aggressive" group (G2-G3 invasive carcinomas) was 0.96×10(-3) mm(2)/s (p<0.001).

CONCLUSION

The study confirms the usefulness of diffusion imaging in assessing the aggressiveness of breast tumours. ADC appears to be a promising parameter in the evaluation of the degree of malignancy of breast cancer tissue.

Apparent Diffusion Coefficient in Invasive Ductal Breast Carcinoma: Correlation with Detailed Histologic Features and the Enhancement Ratio on Dynamic Contrast-Enhanced MR Images

Purpose. To investigate the correlation of Apperent Diffusion Coefficient (ADC) values in invasive ductal breast carcinomas with detailed histologic features and enhancement ratios on dynamic contrast-enhanced MRI. Methods and Materials. Dynamic MR images and diffusion-weighted images (DWIs) of invasive ductal breast carcinomas were reviewed in 25 (26 lesions) women. In each patient, DWI, T2WI, T1WI, and dynamic images were obtained. The ADC values of the 26 carcinomas were calculated with b-factors of 0 and 1000 s/mm² using echoplanar DWI. Correlations of the ADC values were examined on dynamic MRI with enhancement ratios (early to delayed phase: E/D ratio) and detailed histologic findings for each lesion, including cellular density, the size of cancer nests, and architectural features of the stroma (broad, narrow, and delicate) between cancer nests. Results. The mean ADC was 0.915 ± 0.151 × 10⁻³ mm²/sec. Cellular density was significantly correlated with ADC values (P = .0184) and E/D ratios (P = .0315). The ADC values were also significantly correlated to features of the stroma (broad to narrow, P = .0366). Conclusion. The findings suggest that DWIs reflect the growth patterns of carcinomas, including cellular density and architectural features of the stroma, and E/D ratios may also be closely correlated to cellular density.

Diffusion tensor magnetic resonance imaging of the breast: a pilot study

OBJECTIVES

Diffusion-weighted MR imaging has shown diagnostic value for differential diagnosis of breast lesions. Diffusion tensor imaging (DTI) adds information about tissue microstructure by addressing diffusion direction. We have examined the diagnostic application of DTI of the breast.

METHODS

A total of 59 patients (71 lesions: 54 malignant, 17 benign) successfully underwent prospective echo planar imaging-DTI (EPI-DTI) (1.5 T). First, diffusion direction both of parenchyma as well as lesions was assessed on parametric maps. Subsequently, apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured. Statistics included univariate (Mann-Whitney U test, receiver operating analysis) and multivariate (logistic regression analysis, LRA) tests.

RESULTS

Main diffusion direction of parenchyma was anterior-posterior in the majority of cases (66.1%), whereas lesions (benign, malignant) showed no predominant diffusion direction in the majority of cases (23.9%). ADC values showed highest differences between benign and malignant lesions (P<0.001) with resulting area under the curve (AUC) of 0.899. FA values were lower in benign (interquartile range, IR, 0.14-0.24) compared to malignant lesions (IR 0.21-0.35, P<0.002) with an AUC of 0.751-0.770. Following LRA, FA did not prove to have incremental value for differential diagnosis over ADC values.

CONCLUSIONS

Microanatomical differences between benign and malignant breast lesions as well as breast parenchyma can be visualized by using DTI.

Diffusion-weighted imaging of normal fibroglandular breast tissue: influence of microperfusion and fat suppression technique on the apparent diffusion coefficient

The influence of microperfusion and fat suppression technique on the apparent diffusion coefficient (ADC) values obtained with diffusion weighted imaging (DWI) of normal fibroglandular breast tissue was investigated. Seven volunteers (14 breasts) were scanned using diffusion weighting factors (b values) up to 1600 s/mm(2) and the four different fat suppression techniques: STIR, fat saturation, SPAIR, and Water Excitation. The relationship between the logarithmic DW attenuation curves and b was linear for b values up to 600 s/mm(2) (R(2) > 0.999). Small differences were noted between the ADC values obtained with the various fat suppression methods, especially at the higher b values. Water Excitation had the highest mean SNR, exceeding STIR (p = 0.03) though not significantly different from fat saturation and SPAIR. In conclusion, the ADC of fibroglandular breast tissue is not influenced by microperfusion and Water Excitation is recommended because it yielded the best SNR values. These factors may be crucial in the differentiation between benign and malignant lesions.

Diffusion and perfusion of the breast

This article is a review of the current published clinical applications of DWI and perfusion of breast MR explaining possibilities and limits of both techniques. DWI in a fast time acquisition and without contrast medium gives information as regards cellularity of breast lesions. The technique can be used for distinguishing between benign and malignant breast lesions and monitoring therapies in locally advanced breast cancer. Perfusion can give additional information as regards vascularization of breast lesions, useful in the characterization of breast lesions doubt at DCE-MRI and also in monitoring chemotherapic effect.

The role of parallel diffusion-weighted imaging and apparent diffusion coefficient (ADC) map values for evaluating breast lesions: preliminary results

RATIONALE AND OBJECTIVES

To evaluate the feasibility of using diffusion-weighted imaging (DWI) with an array spatial sensitivity encoding technique (ASSET) and apparent diffusion coefficient (ADC) map values with different b values to distinguish benign and malignant breast lesions.

MATERIALS AND METHODS

Fifty-six female patients with 60 histologically proven breast lesions and 20 healthy volunteers underwent magnetic resonance imaging. A subset of normal volunteers (n = 7) and patients (n = 16) underwent both conventional DWI and ASSET-DWI, and the image quality between the two methods was compared. Finally, ASSET-DWI with b = 0, 600 s/mm(2), and b = 0, 1000 s/mm(2), were compared for their ability to distinguish benign and malignant breast lesions.

RESULTS

The ASSET-DWI method had less distortion, fewer artifacts, and a lower acquisition time than other methods. No significant difference (P > .05) was detected in ADC map values between ASSET-DWI and conventional DWI. For ASSET-DWI, the sensitivity of ADC values for malignant lesions with a threshold of less than 1.44 x 10(-3) mm(2)/s (b = 600 s/mm(2)) and 1.18 x 10(-3) mm(2)/s (b = 1000 s/mm(2)) was 80% and 77.5%, respectively. The specificity of both groups was 95%.

CONCLUSION

ASSET-DWI evaluation of breast tissue offers decreased distortion, susceptibility to artifacts, and acquisition time relative to other methods. The use of ASSET-DWI is feasible with b values ranging from 600 to 1000 s/mm(2) and provides increased specificity compared to other techniques. Thus, the ADC value of a breast lesion can be used to further characterize malignant lesions from benign ones.

Diffusion-weighted magnetic resonance imaging for assessment after neoadjuvant chemotherapy in breast cancer, based on morphological concepts

The study aimed to evaluate the utility of diffusion-weighted imaging (DWI) and to assess the response of breast cancer patients to neoadjuvant chemotherapy (NAC), based on morphological concepts. This retrospective study included 35 breast cancer patients (36 lesions) who had conventional magnetic resonance imaging (MRI), with DWI acquired before and after NAC. The morphological pattern of delayed enhancement on MRI before NAC was classified into two types: focal mass (FM), and multiple masses and/or non-mass like (MM/NM), based on Breast Imaging Reporting and Data System (BI-RADS). Of the 36 tumors, 26 were classified as FM and 10 as MM/NM. Tumors were clearly visualized on the initial DWI although one case of suspected MM/NM was not observed on DWI following NAC. A correlation was found between changes in the apparent diffusion coefficient and response rates to NAC in FM tumors (r=0.608, p<0.001), but not in MM/NM tumors (r=0.141, p=0.717). There was agreement between MRI findings after NAC and pathological findings in 30 of the 36 tumors (83.3%). Thus, we concluded that DWI is potentially useful in assessing the response to NAC for breast cancer for tumors diagnosed as FM on the initial conventional MRI.

Diffusion weighted MR imaging of the breast

The aim of this work is to review the techniques and clinical applications of diffusion-weighted magnetic resonance (MR) imaging of the breast. Diffusion-weighted MR imaging plays a role in the differentiation breast cancer from benign lesions, the characterization of malignancy, and the detection of tumor extension. The apparent diffusion coefficient of breast cancer is correlated with tumor cellularity and some prognostic factors of breast cancer. It can be used for the differentiation of recurrent tumors from posttreatment changes and monitoring of patients after chemotherapy. Diffusion-weighted MR imaging is used for the characterization of breast mass, diagnosis, and the grading and staging of breast cancer, as well as prediction of the responses of patients with breast cancer to chemotherapy.