What is the significance of prepontine cistern signal abnormality and scattered white matter changes on MRI in a breast cancer patient post-stroke?

MRI Findings in a Post-Stroke Breast Cancer Patient: Clinical Significance and Management

The prepontine cistern FLAIR and T2 signal abnormality and scattered white matter changes seen on MRI are likely incidental findings that do not require immediate intervention. These findings represent microvascular ischemic changes that are common in post-stroke patients and are not directly related to the patient's breast cancer history.

Prepontine Cistern Signal Abnormality

The persistent prepontine cistern FLAIR and T2 signal abnormality has two main differential considerations:

1. Pulsation artifact: Most likely related to a dominant left vertebrobasilar system
2. Ecchordosis physaliphora: A benign notochordal remnant

Key points:

• This finding is unchanged from previous MRI, suggesting stability
• No aggressive clival lesion is present
• No immediate intervention is required
• For optimal evaluation, a non-emergent MRI with thin cuts using IAC protocol with pre and post IV contrast and delayed postcontrast FLAIR imaging would be recommended 1

Scattered White Matter Changes

The mild scattered white matter changes have several potential etiologies:

• Microvascular ischemia (most common)
• History of migraine headaches
• Toxic or substance exposure

These findings are not significantly changed from previous imaging, indicating stability. White matter changes are common in post-stroke patients and represent small vessel disease 1.

Clinical Significance in Breast Cancer Patients

For breast cancer patients with a history of stroke:

1. No direct relationship to cancer: These MRI findings are not typically related to breast cancer metastasis, which would present differently on imaging 1

2. Stroke risk factors in breast cancer patients:

   • Some breast cancer treatments may increase stroke risk:
     • Radiation to supraclavicular and internal mammary lymph nodes 2
     • Certain chemotherapy regimens 3
   • Tamoxifen has been studied but shows no significant independent association with stroke risk 4, 3
   • Sleep disorders in breast cancer patients may increase stroke risk 5

3. Follow-up recommendations:

   • These findings do not require urgent intervention
   • Regular follow-up with standard breast cancer surveillance is appropriate 1
   • No need for additional brain imaging unless new neurological symptoms develop 1

Management Considerations

1. Breast cancer surveillance should continue as recommended:

   • Annual mammography of intact breast(s) 1
   • No routine MRI breast screening unless patient meets high-risk criteria (lifetime risk >20%) 1
   • No routine advanced imaging (CT, PET, MRI) for asymptomatic surveillance 1

2. For the brain MRI findings:

   • No immediate intervention needed for the prepontine cistern finding
   • Consider non-emergent dedicated IAC protocol MRI with contrast if further characterization is desired
   • Monitor white matter changes as part of routine neurological care for post-stroke patients

3. Patient education:

   • Reassure patient that these findings are likely unrelated to breast cancer
   • Educate about signs/symptoms that would warrant urgent evaluation
   • Continue standard stroke prevention measures (blood pressure control, antiplatelet therapy as indicated)

These MRI findings represent incidental, stable changes that are common in post-stroke patients and do not suggest breast cancer metastasis or require urgent intervention.