MRI BI-RADS: How to make it out?

Transcription

1 MRI BI-RADS: How to make it out? Poster No.: C-1850 Congress: ECR 2016 Type: Educational Exhibit Authors: M. Ben Ammar, A. Ben Miled, O. Ghdes, S. Harguem, A. Gaja, N. Mnif; Tunis/TN Keywords: Breast, MR, Diagnostic procedure, Neoplasia, Cysts DOI: /ecr2016/C-1850 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 31

2 Learning objectives Learn how to report Breast MRI exams according to the last 2013 update of the BI-RADS lexicon Learn how to classify MRI findings using conventional and multiparametric MR imaging, based on a well-structured algorithm presented within the BI-RADS 2013 Page 2 of 31

3 Background Breast Magnetic Resonance Imaging (MRI) is used as an important complementary tool to conventional imaging modalities (mammography and ultrasound) in both detection and characterization of abnormalities suggesting breast cancer. Its increased and widespread use reflects the excellent sensitivity and its high negative predictive value. The latest version of the BI-RADS lexicon published by the American College of Radiology available by the end of 2013 includes an update affecting mammographic, sonographic and MRI lexicon features in order to reduce the variability in techniques and to increase interobserver homogeneity in reporting any breast abnormality. Page 3 of 31

4 Findings and procedure details One of the major aims of MRI BI-RADS 2013 is to simplify and to standardize the terminology and content of radiology reports, and thus reducing variability in imaging interpretations. Three types of abnormal enhancement patterns have been described, namely masses (space-occupying lesions), non-mass enhancements (NME: abnormal enhancements taking place of the gland without representing a space-occupying lesion), and foci (dot enhancements inferior to 5mm) Every lesion has to be well described based on morphological and enhancement criteria; for some of them, distribution has also to be mentioned. Accurate description of these lesions will lead to a specific algorithm that will allow the lector to properly classify breast MRI findings. Correlation between MRI findings, mammography and sometimes second look sonography will enable a reliable assessment based on BI-RADS categories for a better management of breast pathology. - Technical considerations: Conditions required to practice breast MRI: No MRI or gadolinium injection contraindications It is preferable to practice breast MRI in the first half of menstrual cycle If patient is under hormone replacement therapy medication, treatment has to be stopped 6 weeks beforehand If patient is breastfeeding, it has to be suspended 24h after gadolinium injection A period of 6 months is required before practicing breast MRI in case of previous breast surgery Similarly a period of 12 months is required after radiotherapy MRI protocol: Breast surface coil is required T1-weighted sequence in axial plane. T2-weighted sequence in axial plane. Page 4 of 31

5 Diffusion weighted imaging sequence in the axial plane using B values of 0 and 1000s/ 3 mm². Lesions showing hypersignal in B1000 sequence with a low ADC value (<1.13 x10 mm²/s) are suspect of malignancy. Dynamic 3D T1-weighted sequence with fat suppression before and after injection of gadolinium in different phases; subtraction of the images is obtained during postprocessing. T1-weighted sequence in delayed phase after gadolinium injection in sagittal plane for each breast MRI findings: The amount of fibroglandular tissue (FGT) : Defined by the visually estimated content of FGT within the breast 4 categories: Almost entirely fat Scattered FGT Heterogeneous FGT Extreme FGT Background parenchymal enhancement (BPE): (Fig. 18, 19) Defined by the visually estimated enhancement of breast FGT 4 categories: Minimal Mild Moderate Marked Mass: Definition: space occupying three-dimensional lesion > 5mm T2 signal analysis: T2 hypersignal allows characterizing some lesions as benign cyst, lymphocele, hematoma, and fat necrosis. However T2 hyperintensity does not always mean benign lesions. Hypercellular cancers, tumor necrosis and mucinous subtype of cancers are lesions with a T2 hypersignal. Page 5 of 31

6 Shape: (Fig.1,2) Round Oval Irregular NB: the term "macrolobulated" has been removed and replaced by "oval" Margins:(Fig.3) Circumscribed Non circumscribed Irregular Speculated NB: " circumscribed" replaced "smooth" Internal enhancement: Homogeneous Heterogeneous Rim enhancement Dark internal septa NB: the terms "central enhancement "and "enhancing internal septation" have been removed Kinetic curve assessment: (Fig 21) The analysis is based on the signal intensity curve as a function of time Three types of curves are described Type 1: Slow enhancement in the initial phase, persistent enhancement in the delayed phase (after 2 minutes) Type 2: Medium enhancement in the initial phase, plateau in the delayed phase Type 3: Fast enhancement in the initial phase, washout in the delayed phase The fastest enhancing portion of the lesion or the most suspicious washout curve pattern in the lesion should be assessed How to classify a mass? :fig 4,5 Page 6 of 31

7 Focus: dot enhancement that doesn't represent a space occupying lesion and doesn't show a mass on precontrast imaging. Fig 13 Non-mass enhancement (NME): enhancing area that is not a mass NME is analyzed comparatively to the other breast: symmetric or not It should be separated from BPE It may contain interspersed fat NME distribution: Fig 16, 18 Focal: unique or multiple, it only concerns less than 25% of a breast quadrant Regional: it concerns more than 25% of a breast quadrant Multiple regions: >2 Linear and branching linear: replacing "ductal" Segmental: triangular disposition with peak oriented toward the nipple: it is the most suspect pattern of malignancy, with a PPV that rises to 100%. Diffuse NME internal enhancement: Fig 13, 16 Homogeneous Heterogeneous Clumped: mostly associated with segmental NME, described as cobblestone or beaded enhancement. It is correlated with ductal carcinoma in situ. Clustered ring: mostly seen in ductal carcinoma in situ. The reason explaining this enhancement is the accumulation of contrast agent in the perigalactophoric stroma, while there is a washout in tumor vessels. PVV of malignancy: % NME T2 signal: The analysis of T2 signal in the area of NME can provide arguments in favor of whether benign or malignant lesion. In fact, if the T2 signal is due to the presence of microcysts, this feature is associated with a benign lesion. If it represents an edema around the NME area, it is more associated with a malignant lesion. How to classify NME: Fig 15 Associated patterns: Page 7 of 31

8 Nipple or skin retraction Edema Pectoral muscle involvement Skin thickening Lymphadenopathy Precontrast increased ductal signal intensity Non enhanced findings: Ductal precontrast high signal on T1W Cyst Postoperative collections Non-enhanced mass Signal void from foreign bodies, clips. Fat containing lesions: Lymph nodes (fatty hilum) Fat necrosis Hamartoma Postoperative hematoma/seroma with fat. Page 8 of 31

9 Images for this section: Fig. 1 Page 9 of 31

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30 Conclusion Breast MRI is an important imaging technique due to its high sensitivity and great negative predictive value. However its lack of specificity leads to a systematic correlation with other breast imaging modalities. BI-RADS 2013 lexicon leads to a standardized report for a better management of patient's breast disease Page 30 of 31

31 References Weinstein SP, Hanna LG, Gatsonis C, Schnall MD, Rosen MA, Lehman CD. Frequency of malignancy seen in probably benign lesion at contrast-enhanced breast MR imaging: findings from ACRIN Radiology 2010; 255:731-7 AmericanCollegeofRadiology.BreastImagingReportingandDataSystem(BIRADS Atlas)MRI-Lexicon.1sted.Reston,VA:AmericanCollegeofRadiology; AmericanCollegeofRadiology.BreastImagingReportingandDataSystem(BIRADS Atlas)MRI-Lexicon.5thed.Reston,VA:AmericanCollegeofRadiology; Page 31 of 31