Measure residual enhancement in the same way as baseline, describe its pattern (concentric shrinkage vs fragmentation), and state whether the clip is inside residual disease — the surgeon needs extent, not a category.
Orient first
- Complete imaging response does not equal pathological complete response, particularly in HR-positive tumours.
- Fragmented shrinkage leaves scattered disease that a lumpectomy based on the largest fragment would miss.
- The biopsy clip marks the tumour bed even after complete response.
Acquire the study
- Breast MRI with the same protocol as baseline: T2, DWI, dynamic post-gadolinium T1 with subtraction, early phase (60–120 s).
The manoeuvre
- Early post-contrast subtraction: residual enhancement — largest dimension in mm, compared with the baseline.
- Pattern: concentric shrinkage, fragmentation, residual non-mass enhancement.
- Clip position (signal void on T1 and gradient-echo) relative to residual enhancement.
- Axillary nodes: size and cortical thickness compared with the baseline.
- Contralateral breast.
What confirms it
- Residual extent and pattern compared with baseline; pathology gives the final answer.
What licenses you to exclude it
- No residual enhancement is complete imaging response; it does not exclude residual microscopic disease.
The classic misread
- Measuring only the largest fragment of a fragmented response.
- Reading background parenchymal enhancement change as residual disease.