Breast MRI:Updates to BI-RADS Lexicon

T Pousse

JFIM 2013 HONG KONG

Aims

• Recall and illustrate new synthetic items of BI-RADS MRI

•  Insist on changes to the BI-RADS MRI lexicon in this third edition

Technical parameters

•  Dedicated breast coil, pulse sequence, (T2/T2 fat sat), IVC

•  Diffusion weighted or spectroscopy optional

•  T2 weigthed recommanded before IVC

Background Parenchymal Enhancement ( BPE)

•  5 categories - none - minimal - mild - moderate - marked

minimal mild

moderate marked

Influence of Background Parenchymal Enhancement

•  Greater BPE may negatively influence breast MRI performances (DeMartini, AJR 2012 536 patients versus 200 patients) –  Decreasing specificity : increase of abnormal exam (30% vs 23%) –  No significant difference in positive rate of biopsy, cancer yield

•  In the analysis of breast cancers not diagnosed at MRI : less misdiagnosis of detection than caraterisation

Mistakes detection not influenced by BPE (Bouic-Pages Radiology 2012)

•  BPE influenced by hormonal fluctuation ,HRT, or Tamoxifen

Lesions characteristics

•  Morphology – Masses – Non-masse enhancement

– Foci (≤ 5mm)

•  Enhancements Kinetics

Masses

•  Space occupying 3D lesions > 5 mm - shape ( 2D ) - margin - internal rehaussement characteristics - T1-T2 weighted pulses sequences pre/post contrast

Masse shape

Rond Oval (replace macrolobulated)

Irrégular

SHAPE

macrolobulated

Mass margins

Régular Irregular Spiculated

Margins

circumscribed replaced smooth

Irrégular : combined shape+margins

Mass internal enhancement patterns

Homogeneous Heterogeneous Rim enhancement Dark internal septa

Central enhancement

Enhancing internal septation

Rim Enhancement value

•  Bénign –  Inflammatory cyst – Cytosteatonecrosis

•  Malignant

– Triple negative Cancer

RIM ENHANCEMENT K Triple négative

T2- weighted signal intensity on non-contrast images : new mass feature in the revised lexicon!

•  Hypersignal T2 ? – T2 :

•  > Parenchyma •  ≥ FAT

– T2 fat sat: •  > Parenchyma •  ≥ WATER , VESSEL

T2 Hypersignal : mechanism Bénign •  Cystic and microcystic comp. •  Altered fat •  Fibroadenoma, intrammary lymph node,

phyllodes tumor Malignant •  Tumor necrosis •  Mucinous subtype cancer

Family juvenile papillomatosis

Mucinous cancer

CCI grade 3

Non-Mass Enhancement

Enhancing area that is not a mass , separate from background parenchymal enhancement may contain interspersed fat

– Distribution (symetric or asymetric) –  Internal enhancement characteristics – T2 weighted signal intensity

Fat area or normal parenchyma inside enhancement

NME distribution

•  Focal area ( <25% Q) •  Linear •  Branching linear : replace ductal •  Segmental •  Regional •  Multiple regions >2 •  Diffuse •  Symetric or not

Focal zone

<25% Q

Often mixed with fat or normal matrix

Distribution : linear enhancement

Distribution : linear enhancement

DUCTAL

Benign NME linear enhancement

Linear branching

Segmental

Symetric or asymetric

Diffuse bilateral

symetric enhancement

Symetric or asymetric •  Asymetric

Regional, bilateral and asymetric enhancement

NME internal enhancement •  Homogeneous •  Heterogeneous •  Stippled ( multiple punctuate foci : benign BPE) •  Clumped (cobblestone ,beaded enhancement ) •  Clustered ring enhancement

Reticular /dendritic Clustered ring (ductal carcinoma in situ) Stippled :BPE

Ring enhancement

Ring Enhancement

PPV of malignancy = 70-100%

Ductal carcinoma

invasive cancer associated with ductal carcinoma in situ

Uematsu AJR 2012 Non masse 3T

Tozaki AJR 2006

T2 Signal

t 0 = 0 t 1 = 2.5 t 2 = 7.5 Time (min)

1

2

3

S 1 S 2

Plateau

Wash out

Persistent S 0

IV contrast"

St2" St1" St0"

Rapid (intense)"Medium"Persistent "

ROI > 3 pixels More suspicious area

Kinetic curve assessment

Kinetic enhancement

Temps (min)

1

2

3

2

Plateau

Wash out ROI > 3 pixels More suspicious area

Persistent

Kinetic curve assessment •  Initial Phase (2 mns) (intensity + speed)

- slow : < 50% - medium : 50-100% - rapid : > 100%

•  Delayed Phase - persistent - plateau - Wash out

Qualitative appreciation

No quantitative cut – off

Menopausis status impact / kinetic curve enhancement (Milllet Radiology 2013)

Associated findings

•  Nipple or skin retraction •  Skin thickening ( focal or diffuse) •  Edema •  Lymphadenopathy •  Pectoralis muscle involvement •  Precontrast increased ductal signal intensity •  Susceptibility artifact related to surgical clips

Implants •  Material type : silicone, saline •  Location: retro-glandular or retropectoral •  Intra or extra-capsular rupture

Using new lexicon

•  PPV for malignancy:mass –  Irregular shape and margin – Spiculated – Ring sign – Heterogeneous – Wash out kinetics

•  PPV for malignancy : non mass – Distribution : linear branching and segmental –  Internal enhancement : clumped and

clustered ring

Breast MRI interpretation

•  BI-RADS IRM – 0 : if suspicion of benign lesion (ex : FA) –  4 : biopsy recommended ( even if US performed for

choice of the guidance) – 3 (PPV variable in MRI)

•  Global BI-RADS : combined reporting with mammography / US

Conclusion

•  T2 weighted sequence •  Background parenchymal enhancement •  Masses / non masses enhancement :

simplification •  Breast implant •  Management / facilitation patient care : BIRADS

0, 4, 3 •  BIRADS global

Thanck you Patrice