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KEY FACTS
Terminology
Imaging
Top Differential Diagnoses
TERMINOLOGY
Definitions
Diffusion-weighted imaging (DWI)
Advanced MR technique that quantifies diffusion of water through tissue, reflecting local cell density and tissue microstructure
Application of diffusion-sensitizing gradients to MR pulse sequence allows water molecule displacement to be recognized
Diffusion signal is modeled and characterized as anisotropic (planar) or isotropic (equal in all directions)
Isotropic diffusion is most relevant for breast cancer cells
Allows estimation of cellularity and tissue structure
Malignant lesions and metastases usually show limited motion of free water molecules = restricted diffusion
DWI provides different information, complementary to dynamic contrast-enhanced MR (DCE-MR)
Sensitive to factors affecting microscopic water motion (e.g., cell density, membrane integrity, tissue microstructure)
Currently used as adjunct to DCE-MR
DWI can be quantitative by calculating apparent diffusion coefficient (ADC)
Diffusion restriction
Motion of free water molecules is limited (diffusion restriction) directly in proportion to tissue cellularity
Typically seen in malignancies, metastases, and cellular neoplasms, which contain higher number of cells per volume than healthy tissue
Higher diffusion restriction → hyperintense on DWI
Brownian motion
Constant, random microscopic motion of free water molecules due to thermal energy
Motion of intracellular water molecules impeded by cell microenvironment, extracellular water molecules impeded by cell membranes
Echo-planar imaging (EPI) DWI
Spin-echo EPI DWI most popular clinical imaging technique for generating diffusion-weighted images
2 diffusion-sensitizing magnetic field gradients applied on either side of 180° radiofrequency refocusing pulse before EPI data collection
b-value: Degree of diffusion weighting expressed in s/mm²
Multiple sequences, using differing b-values (typically ranging from low b-value of 0-100 to high b-value of 800-1,500 s/mm²) → calculate ADC
At very low b-values (< 100 s/mm²), ADC predominantly reflects larger distances of water movement, likely due to faster movement in microvessels
ADC value
Quantitative measure of diffusion defining area covered by molecule per unit of time and measured in mm²/s
Derived logarithmic parameter of signal change with b-value
Based on attenuation of signal intensity between at least 2 diffusion-weighted images of lower and higher b-value
↑ number of acquisitions with different b-values generates more accurate ADC values
ADC map
Parametric image with gray or color scale, representing ADC values of voxels
Correlate with DWI for interpretation
Usually generated by dedicated software
T2 shine-through
In tissues with very long transverse relaxation times, hyperintense T2 signal may be mistaken for restricted diffusion
Correlation with ADC map is needed to distinguish true restricted diffusion (low ADC values) from T2 shine-through (high ADC values)
IMAGING
MR Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Reporting Tips
Selected References
Amornsiripanitch N et al: Diffusion-weighted MRI characteristics associated with prognostic pathological factors and recurrence risk in invasive ER+/HER2- breast cancers. J Magn Reson Imaging. 48(1):226-36, 2018
Amornsiripanitch N et al: Visibility of mammographically occult breast cancer on diffusion-weighted MRI versus ultrasound. Clin Imaging. 49:37-43, 2018
Newitt DC et al: Test-retest repeatability and reproducibility of ADC measures by breast DWI: results from the ACRIN 6698 trial. J Magn Reson Imaging. ePub, 2018
Partridge SC et al: Diffusion-weighted MRI findings predict pathologic response in neoadjuvant treatment of breast cancer: the ACRIN 6698 Multicenter Trial. Radiology. 180273, 2018
Surov A et al: Can diffusion-weighted imaging predict tumor grade and expression of Ki-67 in breast cancer? A multicenter analysis. Breast Cancer Res. 20(1):58, 2018
Partridge SC et al: DWI in the assessment of breast lesions. Top Magn Reson Imaging. 26(5):201-209, 2017
Partridge SC et al: Diffusion-weighted breast MRI: Clinical applications and emerging techniques. J Magn Reson Imaging. 45(2):337-355, 2017
Brandão AC et al: Breast magnetic resonance imaging: diffusion-weighted imaging. Magn Reson Imaging Clin N Am. 21(2):321-36, 2013
Richard R et al: Diffusion-weighted MRI in pretreatment prediction of response to neoadjuvant chemotherapy in patients with breast cancer. Eur Radiol. 23(9):2420-31, 2013
Martincich L et al: Correlations between diffusion-weighted imaging and breast cancer biomarkers. Eur Radiol. 22(7):1519-28, 2012
Wu LM et al: Can diffusion-weighted MR imaging and contrast-enhanced MR imaging precisely evaluate and predict pathological response to neoadjuvant chemotherapy in patients with breast cancer? Breast Cancer Res Treat. 135(1):17-28, 2012
Kul S et al: Contribution of diffusion-weighted imaging to dynamic contrast-enhanced MRI in the characterization of breast tumors. AJR Am J Roentgenol. 196:210-7, 2011
Malayeri AA et al: Principles and applications of diffusion-weighted imaging in cancer detection, staging, and treatment follow-up. Radiographics. 31(6):1773-91, 2011
O'Flynn EA et al: Functional magnetic resonance: biomarkers of response in breast cancer. Breast Cancer Res. 13(1):204, 2011
Woodhams R et al: Diffusion-weighted imaging of the breast: principles and clinical applications. Radiographics. 31(4):1059-84, 2011
Partridge SC et al: Apparent diffusion coefficient values for discriminating benign and malignant breast MRI lesions: effects of lesion type and size. AJR Am J Roentgenol. 194(6):1664-73, 2010
Sinha S et al: Recent advances in breast MRI and MRS. NMR Biomed. 22(1):3-16, 2009
Charles-Edwards EM et al: Diffusion-weighted magnetic resonance imaging and its application to cancer. Cancer Imaging. 6:135-43, 2006
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References
Tables
Tables
KEY FACTS
Terminology
Imaging
Top Differential Diagnoses
TERMINOLOGY
Definitions
Diffusion-weighted imaging (DWI)
Advanced MR technique that quantifies diffusion of water through tissue, reflecting local cell density and tissue microstructure
Application of diffusion-sensitizing gradients to MR pulse sequence allows water molecule displacement to be recognized
Diffusion signal is modeled and characterized as anisotropic (planar) or isotropic (equal in all directions)
Isotropic diffusion is most relevant for breast cancer cells
Allows estimation of cellularity and tissue structure
Malignant lesions and metastases usually show limited motion of free water molecules = restricted diffusion
DWI provides different information, complementary to dynamic contrast-enhanced MR (DCE-MR)
Sensitive to factors affecting microscopic water motion (e.g., cell density, membrane integrity, tissue microstructure)
Currently used as adjunct to DCE-MR
DWI can be quantitative by calculating apparent diffusion coefficient (ADC)
Diffusion restriction
Motion of free water molecules is limited (diffusion restriction) directly in proportion to tissue cellularity
Typically seen in malignancies, metastases, and cellular neoplasms, which contain higher number of cells per volume than healthy tissue
Higher diffusion restriction → hyperintense on DWI
Brownian motion
Constant, random microscopic motion of free water molecules due to thermal energy
Motion of intracellular water molecules impeded by cell microenvironment, extracellular water molecules impeded by cell membranes
Echo-planar imaging (EPI) DWI
Spin-echo EPI DWI most popular clinical imaging technique for generating diffusion-weighted images
2 diffusion-sensitizing magnetic field gradients applied on either side of 180° radiofrequency refocusing pulse before EPI data collection
b-value: Degree of diffusion weighting expressed in s/mm²
Multiple sequences, using differing b-values (typically ranging from low b-value of 0-100 to high b-value of 800-1,500 s/mm²) → calculate ADC
At very low b-values (< 100 s/mm²), ADC predominantly reflects larger distances of water movement, likely due to faster movement in microvessels
ADC value
Quantitative measure of diffusion defining area covered by molecule per unit of time and measured in mm²/s
Derived logarithmic parameter of signal change with b-value
Based on attenuation of signal intensity between at least 2 diffusion-weighted images of lower and higher b-value
↑ number of acquisitions with different b-values generates more accurate ADC values
ADC map
Parametric image with gray or color scale, representing ADC values of voxels
Correlate with DWI for interpretation
Usually generated by dedicated software
T2 shine-through
In tissues with very long transverse relaxation times, hyperintense T2 signal may be mistaken for restricted diffusion
Correlation with ADC map is needed to distinguish true restricted diffusion (low ADC values) from T2 shine-through (high ADC values)
IMAGING
MR Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Reporting Tips
Selected References
Amornsiripanitch N et al: Diffusion-weighted MRI characteristics associated with prognostic pathological factors and recurrence risk in invasive ER+/HER2- breast cancers. J Magn Reson Imaging. 48(1):226-36, 2018
Amornsiripanitch N et al: Visibility of mammographically occult breast cancer on diffusion-weighted MRI versus ultrasound. Clin Imaging. 49:37-43, 2018
Newitt DC et al: Test-retest repeatability and reproducibility of ADC measures by breast DWI: results from the ACRIN 6698 trial. J Magn Reson Imaging. ePub, 2018
Partridge SC et al: Diffusion-weighted MRI findings predict pathologic response in neoadjuvant treatment of breast cancer: the ACRIN 6698 Multicenter Trial. Radiology. 180273, 2018
Surov A et al: Can diffusion-weighted imaging predict tumor grade and expression of Ki-67 in breast cancer? A multicenter analysis. Breast Cancer Res. 20(1):58, 2018
Partridge SC et al: DWI in the assessment of breast lesions. Top Magn Reson Imaging. 26(5):201-209, 2017
Partridge SC et al: Diffusion-weighted breast MRI: Clinical applications and emerging techniques. J Magn Reson Imaging. 45(2):337-355, 2017
Brandão AC et al: Breast magnetic resonance imaging: diffusion-weighted imaging. Magn Reson Imaging Clin N Am. 21(2):321-36, 2013
Richard R et al: Diffusion-weighted MRI in pretreatment prediction of response to neoadjuvant chemotherapy in patients with breast cancer. Eur Radiol. 23(9):2420-31, 2013
Martincich L et al: Correlations between diffusion-weighted imaging and breast cancer biomarkers. Eur Radiol. 22(7):1519-28, 2012
Wu LM et al: Can diffusion-weighted MR imaging and contrast-enhanced MR imaging precisely evaluate and predict pathological response to neoadjuvant chemotherapy in patients with breast cancer? Breast Cancer Res Treat. 135(1):17-28, 2012
Kul S et al: Contribution of diffusion-weighted imaging to dynamic contrast-enhanced MRI in the characterization of breast tumors. AJR Am J Roentgenol. 196:210-7, 2011
Malayeri AA et al: Principles and applications of diffusion-weighted imaging in cancer detection, staging, and treatment follow-up. Radiographics. 31(6):1773-91, 2011
O'Flynn EA et al: Functional magnetic resonance: biomarkers of response in breast cancer. Breast Cancer Res. 13(1):204, 2011
Woodhams R et al: Diffusion-weighted imaging of the breast: principles and clinical applications. Radiographics. 31(4):1059-84, 2011
Partridge SC et al: Apparent diffusion coefficient values for discriminating benign and malignant breast MRI lesions: effects of lesion type and size. AJR Am J Roentgenol. 194(6):1664-73, 2010
Sinha S et al: Recent advances in breast MRI and MRS. NMR Biomed. 22(1):3-16, 2009
Charles-Edwards EM et al: Diffusion-weighted magnetic resonance imaging and its application to cancer. Cancer Imaging. 6:135-43, 2006
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