Pitfalls and Limitations of Breast MRI Susan Orel Roth, MD Professor of Radiology University of Pennsylvania
Objectives Review the etiologies of false negative breast MRI examinations Discuss the limitations in differentiating benign from malignant lesions Discuss the pitfalls of MRI-guided breast intervention
False Negatives MRI is highly sensitive for the detection of invasive breast cancer Sensitivities >90% MRI is highly sensitive for the detection of DCIS Sensitivity more variable (40-100%) Can detect DCIS that is mammo occult There are invasive and non-invasive cancers which will not be detected with MRI False negative rate 4-12%
False Negatives Technical Interpretation errors True false negatives
Technical False Negatives Poor image quality Fat suppression/image subtraction Patient motion Suboptimal positioning Problem with contrast injection
Images of 43-year-old with (+) axillary node Post-contrast Subtraction
Inhomogeneous fat suppression
Active Plus Passive Fat Suppression Post-contrast Subtraction
Pre Post Subtraction
Patient Motion: Effects on Subtraction Images Pre-gad Post-gad Subtract Slice 1 Slice 2
Pitfall: Suboptimal patient positioning Suspicious lesion in axillary tail on contrast tomosynthesis MRI did not visualize mass in corresponding area
MRI repeated to include high axillary tail
Positioning: Include as much breast tissue as possible Area of concern (if known) should be included
Pre contrast Post contrast Subtraction Contrast infiltrated
Subtraction Pre contrast Post contrast Patient returned on another day
False Negatives Technical Interpretation errors Unilateral imaging Lack of correlation with other imaging tests
Pitfall of Unilateral Imaging Pre-contrast Post-contrast
Lack of correlation with other imaging modalities 1999 2001
Axial T1W Sagittal T1W MRI interpretation: Normal Pre-gad Post-gad
Equivocal Mammographic/US Finding for which MRI recommended BI-RADS category 0, incomplete MRI recommended If MRI negative, define what follow-up is needed If MRI positive: If biopsy recommended, what modality? Correlation of MRI with mammogram/us is critical One final BI-RADS recommendation
Technical False Negatives Interpretation errors True false negatives Invasive cancers or DCIS obscured by background enhancement Absence of enhancement
False negative due to background enhancement
Moderate background parenchymal enhancement bilateral axillary tail Newly diagnosed DCIS right axillary tail R L
False negative: Patient with palpable mass L L L Excisional biopsy: Invasive lobular cancer
False Negative Due to Absence of Enhancement Schnall MD, et al. Radiology 2006; 208: 42 Prospective multicenter trial identified 995 lesions in 854 women for whom pathology available Absence of enhancement associated with 88% NPV NPV of non-enhancement for invasive cancer 94% 25/208 lesions reported no enhancement proved to be malignant 12 DCIS (16% of 77 DCIS lesions) 13 invasive (3% of 422 invasive cancers)
Assessment of false-negative cases of MRI in women with a familial or genetic predisposition Obdeijn IA, et al. Breast Cancer Res Treat 2010; 119:399 Retrospective analysis of false negatives Dutch MRI screening study; nonrandomized prospective multicenter trial 1999-2006; 2,157 women screened yearly with mammography and MRI 97 cancers in 93 patients; 19 (20%) DCIS detected 21 false negative cases
Assessment of false-negative cases of MRI in women with a familial or genetic predisposition Obdeijn IA, et al. Breast Cancer Res Treat 2010; 119:399 21 false negatives 12/21 negative on review 8 DCIS (7-50 mm; mean 20 mm) 4 invasive; background enhancement 9/21 visible in retrospect 4-5 mm round lesion; benign kinetics (3) Misinterpreted as benign enhancement (3) Missed (3)
Undiagnosed Breast Cancer at MR Imaging: Analysis of Causes Pages EB, et al. Radiology 2012; 264:40 Retrospective review of false negative cases 60 cancers in 58 women 28 (47%) of 60 cancers were retrospectively identified 15 (25%) potentially misinterpreted Smooth margins (4); stability (3); post-op (5) 7 (12%) mismanaged Mainly due to inadequate correlation with US; inaccurate US sampling 6 (10%) not identified prospectively
False negatives Pitfalls/Limitations Overlap in MRI appearances of benign and malignant lesions Morphology Kinetics
Masses with High SI on T2W FSE Most masses with high SI on T2W images will be benign Cysts Fibroadenomas Lymph nodes But, cancers with cystic component may also have SI Colloid (mucinous) Intracystic cancer Others
T2 FSE Cysts Post-contrast Fibroadenoma Lymph node
T2 FSE Post-contrast
Colloid Cancer MRI interpretation: cysts History of solid masses on US Pathology: colloid cancer
Morphology of Enhancing Lesions Features with highest PPV for malignancy Masses Spiculated margin Rim enhancement Irregular shape Non-mass enhancement Segmental Clumped linear or ductal
Rim enhancement Irregular borders Invasive carcinoma
Rim enhancement in fat necrosis
radial Scar fat necrosis Mastitis mastitis sclerosing adenosis
Time intensity curves SI Type I persistent 83% benign lesions* Type II plateau Type III washout 57% malignant lesions* Time *Kuhl CK. Eur Radiol 2000
Wash-out in invasive cancer 90 sec 3.5 3 2.5 2 180 sec 1.5 1 0.5 0 0 100 200 300
Morphology and Kinetics: Benign morphology Suspicious kinetics Use most suspicious feature Courtesy D. David Dershaw, MSKCC
1 st post Delayed axial 2 nd post 3 rd post Persistent increasing enhancement in 5 mm invasive ductal cancer
Persistent increasing enhancement in DCIS 90 sec 180 seconds
False negatives Pitfalls/Limitations Overlap in MRI appearances of benign and malignant lesions MRI guided intervention
Pitfalls/Limitations of MR guided intervention Can be difficult (impossible) to document successful lesion removal or sampling Contrast washes out of lesion during procedure Lesion no longer visible after biopsy Was it removed at biopsy or did it wash-out? Obscured by post-biopsy hematoma Is clip in accurate position? Lesion usually not visible on post-localization mammogram Where is lesion along wire? Lesion usually not visible on specimen radiograph Careful radiologic-pathologic correlation
History: Newly diagnosed cancer MRI detected additional lesion
Newly diagnosed breast cancer Contralateral breast: 7mm enhancing mass Pathology: tiny papilloma
MR-guided wire localization Pathology: invasive ductal cancer
Clip migration
Pitfall: No enhancement identified at time of biopsy
Pitfall: Hormonal variation Varying enhancement over 2 week period in high risk patient
Menstrual Cycle Effects on Contrast Enhancement Contrast enhancement of the breast shown to vary with the menstrual cycle Lowest in week 2 Highest in weeks 1 and 4 Lesions with suspicious enhancement may resolve on follow-up MRI at different point in menstrual cycle For screening, ideal to scan days 7-14 For biopsy, also ideal to scan days 7-14
Post gad Post biopsy Biopsy site Pathology: LCIS
Follow-up MRI in 3 weeks
Follow-up of lesions detected by MRI but not biopsied due to absence of enhancement Hefler, et al. Eur Radiol 2003; 13(2):344 37 of 291 biopsies aborted due to absence of enhancement 6 lost to follow-up 2 biopsied anyway (could see w/o contrast) 25 of 29 no enhancement verified on MR f/u (< 6mo) without compression 4 of 29 enhancement reappeared 3 of 4 malignant
Cancellation of MRI-guided breast biopsy due to lesion non-visualization: frequency and follow-up Brennan SB,et al. Radiology 2011; 261:92 907 patients; 2004-2008 Cancellation of biopsy 8% of patients Factors associated with cancellation Marked and moderate background enhancement Extremely and heterogeneously dense on mammography Lesions < 1cm in size Highest in first year 58 women with MRI follow-up no cancers found 3 women mastectomy one had DCIS
What if Lesion Does Not Enhance at time of Localization or Core Biopsy? Not uncommon possibility should be explained to patient during informed consent Is MR imaging follow-up needed? Will depend of level of suspicion of MRI finding No follow-up needed Low suspicion 6 month follow-up Immediate follow-up High suspicion
Patient outcomes in canceled MRIguided breast biopsies Niell BL, et al. AJR 2014; 202:223 January 1, 2007-December 31, 2009 350 patients with 445 lesions scheduled for MRI biopsy MRI biopsy aborted 13% (56/445) lesions and 15% (53/350) patients due to nonvisualization of lesion 50/53 had follow-up Malignancy found in 5/50 (10%); 3 IDC and 2 DCIS (mean time 2.6 months)
Cancellation of MRI-guided breast biopsy due to lesion nonvisualization: frequency and follow-up Brennan SB, et al. Radiology 2011;261 2004-2008 907 patients scheduled for MRI biopsy 70 (8%)patients had biopsy canceled due to nonvisualization of lesion 58 patients had MRI follow-up no cancers identified 3 patients who underwent mastectomy, one had DCIS in same quadrant
Conclusions False negative MRI Careful attention to technique Must correlate MRI with mammography and ultrasound Are true false negatives Both DCIS and invasive cancer Negative MRI does not exclude the presence of breast cancer
Conclusions Overlap in MRI appearances of benign and malignant lesions Overlap in morphology and kinetics Hormonal variation Ideal to schedule screening MRI days 7-14 of the menstrual cycle to reduce background parenchymal enhancement Need for MRI-guided breast intervention
Conclusions MRI-guided intervention False negative cases Difficult (impossible) to document successful lesion sampling / removal Need careful rad-path correlation Repeat immediately if highly suspicious Repeat in 6 months if benign and probably concordant