Mass T2 Signal — Not Hyperintense
Not hyperintense T2 signal indicates the mass is not uniformly bright on T2-weighted imaging — not as bright as a normal lymph node.
Definition
The mass is not uniformly bright throughout and is not “lymph node bright” on fat-suppressed T2-weighted imaging. This includes masses that are:
- Isointense to normal breast parenchyma
- Hypointense relative to a lymph node
- Heterogeneous (some areas bright, others not — e.g., necrosis)
Imaging Appearance
- Fat-suppressed T2W: mass signal not reaching lymph node brightness
- May be intermediate signal, dark, or heterogeneous
- Exception: central necrosis may create a bright T2 center within an otherwise not-hyperintense tumor
Significance
The lack of T2 hyperintensity removes one of the four benign-favoring criteria — the mass cannot achieve the ≤ 2% cancer risk threshold without T2 hyperintensity.
However, not hyperintense T2 signal is not independently suspicious — it is a neutral finding. Most invasive cancers are not T2 hyperintense.
Association with Malignancy
The majority of invasive breast cancers are NOT T2 hyperintense:
- IDC — typically intermediate or low T2 signal
- ILC — typically low T2 signal
- High-grade tumors may have heterogeneous T2 (necrosis = bright center)
Examples from Source
- Irregular + spiculated + heterogeneous + NOT hyperintense → IDC
- Irregular + indistinct + heterogeneous + NOT hyperintense → IDC
- Oval + indistinct + heterogeneous + NOT hyperintense → IDC
- Portions hypointense relative to axillary lymph node → IDC
When to Report
Report T2 signal intensity when it influences assessment — particularly when the mass has some benign-favoring features (oval, circumscribed) and you need T2 to complete the ≤ 2% assessment.