Pitfalls in breast MRI : How to deal between

Sensitivity and Specifcity ?

P. Taourel, E. Pages

Breast MRI : a weak specificity •  Studies comparing MRI and MG

–  Staging of brast cancer : Spe = 70% close to Spe of MG

–  High risk women : Spe = 90 % •  Why this feeling of low specificity

–  enhancement ≠ cancer –  Lack of experience –  Difficulty of biopsy

C Kuhl Radiology 2007

Breast MRI : is it perfectly sensitive ? •  The sensitivity of an exam depends of the gold standard > 95 % in most of the studies ≈ 75 % in screening studies = 85 % in the stidy with gold standard = pathologic analysis of mastectomy •  MRI Sensitivity > Sensitivity of other imaging modalities

Causes of avoidable F+

•  Artefacts •  Normal structures •  Benign tumors

Causes of avoidable F+

•  Artefacts •  Normal structures •  Benign tumors

Backround enhancement

•  Bilateral and symmetric

•  Hormonal and therapeutic context

•  Age of the patient •  The backround

enhancement must be graded

Genetic risks, BRCA 1

40 years old

Genetic risks

40 years old

Right mass : fibroadenoma

ovariectomy

To analyze / classification BIRADS

•  Mass –  3D –  Cancer, FA, papilloma, fat necrosis, sclerosing

adenosis, lymph node, some atypical form of benign lesions

–  Key features for Benign: •  Smooth outline •  Regular form •  Homogeneous enhancement (value if big) •  Hyper T2 •  Fat content •  Weak enhancement and no wash-out

2009 2010

Value of hyper T2 if homogeneous

Rim must be analyzed according to the content and the regular pattern

To analyze / BIRADS classification

•  Non mass enhancement – Neither mass nor focus – Benign mass, young patient, inflammation,

DCIS, ILC – Key features for enhancement :

•  Bilateral and symmetric •  Cysts ++ •  Negative findings

To analyze / classification BIRADS

•  Focus – < 5 mm – Very low rate of malignancy – Key features for benign (no F.U = BIRADS 2)

•  Multiple •  No wash-out •  Clinical context

F -

•  Lack of enhancement •  Not seen

– Backround enhancement, artefact – small – Tricky area

•  Misinterpretation •  Mismanagement

Causes of False negative

•  Retrospective review of 60 pairs of breast cancer

•  47% of « errors » – 10% = misdiagnosis – 25% = misinterpretation – 12% = mismanagement

Pages Radiology 2012

Lack of enhancement

•  DCIS •  Small invasive cancer •  Some pathologic pattern:

–  Inflammatory cancer –  Invasive lobular carcinoma

F -

•  Lack of enhancement •  Not seen

– Backround enhancement, artefact – small – Tricky area

•  Misinterpretation •  Mismanagement

Oct 2004 Mai 2005

1an plus tard

F -

•  Lack of enhancement •  Not seen

– Backround enhancement, artefact – small – Tricky area

•  Misinterpretation •  Mismanagement

2007  

2008  

Benign morphology’’ : oval form, smooth outlines, non enhanced septas

Forme ronde Phénotype triple-négatif

RE-

RP-

HER2 -

Benign/malignant association

1 year later

2003

2005

2006

Be careful with kinetic, particularly in menopausal patients

Temps (min)

1

2

3

2

Plateau

Lavage

Progressive

ROI > 3 pixels Région la plus suspecte

OR not to have malignant curve in menopausal patients : 2.94 : initial rise 2.38 : washout I Millet Radiology dec 2013 -

F -

•  Lack of enhancement •  Not seen

– Backround enhancement, artefact – small – Tricky area

•  Misinterpretation •  Mismanagement

• Retrocystic enhancement

Importance du clip

How to avoid F+ and F- ?

1.  To recognize the pseudo-enhancement 2.  To negative normal structure : bilateral foci,

punctuate enhancement, lymph nodes 3.  6 month FU 4.  Interpretation according to clinical context and

personal status - focus/BIRADS - enhancement/menopausal status

5.  Be careful with stability (morphology +++) 6.  Be careful with autosatisfaction : FU of benign

results in biopsy performed on 2d look US