7.2 Staging Workup: When to Use MRI, CT, Bone Scan & PET
Key Takeaways
Routine systemic imaging with CT, bone scan, or PET is not recommended for asymptomatic clinical stage I to II breast cancer because metastases are rare and false positives are common.
Systemic staging with contrast CT of the chest, abdomen, and pelvis plus a bone scan, or FDG PET/CT, is recommended for clinical stage III disease, inflammatory breast cancer, or symptoms or labs suggesting metastasis.
Symptom-directed imaging matches the complaint: bone pain or rising alkaline phosphatase prompts a bone scan, abnormal liver tests prompt abdominal imaging, and neurologic symptoms prompt brain MRI.
Tissue expanders with magnetic ports are an MRI safety hazard, so nurses screen every patient for implants and devices before MRI.
The Baseline Workup
For every newly diagnosed invasive breast cancer, the core workup includes:
- History and physical examination, including nodal basins and menopausal status.
- Bilateral diagnostic mammography, with ultrasound of the breast and axilla as needed.
- Pathology review with histologic type, grade, ER, PR, and HER2.
- Genetic counseling and testing when criteria are met, fertility counseling for patients of reproductive age, pregnancy testing when relevant, and distress screening.
- Laboratory tests such as a complete blood count and comprehensive metabolic panel with liver tests and alkaline phosphatase, used mainly to guide treatment or when systemic imaging is being considered.
The CBCN outline separates clinical and pathologic staging (covered in the AJCC section) from additional studies: MRI, bone scan, CT, and PET.
When Systemic Imaging Is Not Indicated
For asymptomatic clinical stage I and II disease, NCCN and the ASCO Choosing Wisely list recommend against routine CT, bone scan, or PET. Distant metastases are found in only a small fraction of these patients, while incidental findings (liver cysts, lung nodules, degenerative bone changes) trigger anxiety, delay, extra biopsies, and radiation exposure. Tumor markers are also not used to stage early breast cancer.
When Systemic Imaging Is Indicated
| Situation | Typical imaging |
|---|---|
| Clinical stage III (for example T3 N1, any N2 or N3, or T4) | Contrast CT of chest, abdomen, and pelvis plus bone scan, or FDG PET/CT |
| Inflammatory breast cancer | Full systemic staging; about one third have metastases at diagnosis |
| Bone pain or elevated alkaline phosphatase | Bone scan (or FDG PET/CT) |
| Abnormal liver tests, abdominal symptoms, or abdominal findings | Contrast CT or MRI of the abdomen |
| Pulmonary symptoms | Contrast CT of the chest |
| Neurologic symptoms | Contrast-enhanced brain MRI |
Many teams also stage selected stage II patients with high nodal burden or aggressive biology who are starting preoperative therapy. Brain MRI is not routine in asymptomatic early disease.
What Each Study Shows
- Breast MRI: the most sensitive test for extent of disease in the breast. Useful for occult primary cancer presenting as axillary metastasis, invasive lobular carcinoma, very dense breasts, discrepancies between exam and imaging, Paget disease with negative mammography, and response to neoadjuvant therapy. Routine preoperative MRI has not been shown to reduce re-excision or recurrence and can increase mastectomy rates, so it is used selectively.
- Contrast CT: evaluates lungs, liver, nodes, and bone windows. Requires iodinated contrast.
- Bone scan (skeletal scintigraphy): a technetium-99m–labeled phosphonate is injected, and images are taken 2 to 4 hours later. It detects osteoblastic activity; purely lytic lesions can be missed, and healing bone after treatment can "flare" and look worse.
- FDG PET/CT: shows glucose uptake. Most helpful when standard imaging is equivocal and in stage III or metastatic disease. Low-grade and lobular tumors can have low FDG uptake. If PET/CT clearly shows bone metastases, a separate bone scan can be omitted.
- FES PET/CT (fluoroestradiol): an FDA-approved tracer that shows estrogen receptor-positive lesions, used in recurrent or metastatic disease when biopsy is difficult. Patients stop tamoxifen and fulvestrant for a washout period beforehand because they block uptake.
Nursing Preparation and Safety
| Study | Nursing checks |
|---|---|
| Contrast CT | Contrast allergy history and premedication protocol; kidney function (eGFR); hydration; metformin instructions per policy; IV access |
| MRI with gadolinium | Screen for pacemakers, neurostimulators, aneurysm clips, and tissue expanders with magnetic ports, which are MRI-unsafe; kidney function; claustrophobia plan; prone positioning for breast MRI |
| Bone scan | Explain the 2- to 4-hour wait after injection; encourage fluids and voiding; small radiation dose that clears in urine |
| FDG PET/CT | Fast 4 to 6 hours; check blood glucose (facilities usually proceed when it is under about 200 mg/dL); avoid strenuous exercise for 24 hours; stay warm and still during uptake |
Premenopausal patients having breast MRI for screening are scheduled on days 7 to 14 of the cycle to reduce background enhancement; diagnostic staging MRI is not delayed for cycle timing. Always confirm pregnancy status before imaging with radiation or gadolinium.
Helping Patients Understand Staging
Patients often expect "full-body scans" and feel reassured by them. Explain that in early-stage disease scans are more likely to find harmless spots than real cancer, and that treatment decisions come from the tumor's size, nodes, and biology. When scans are ordered, prepare the patient for the possibility of indeterminate findings and the timeline for results.
Restaging: After Neoadjuvant Therapy and at Recurrence
- During and after neoadjuvant therapy: clinical examination and breast imaging (ultrasound or MRI) track response and guide surgery. A clip placed in the tumor and in any biopsy-proven node before treatment lets the surgeon find the tumor bed even after a complete clinical response. Systemic imaging is repeated only for new symptoms or signs of progression.
- Suspected recurrence: biopsy the first recurrence whenever feasible to confirm breast cancer and retest ER, PR, and HER2, because receptor status changes between the primary tumor and metastases in a meaningful minority of patients and can change treatment. Stage with contrast CT of the chest, abdomen, and pelvis plus bone scan, or FDG PET/CT, and add brain MRI for neurologic symptoms.
- Metastatic disease monitoring: imaging every few months, symptom review, and sometimes tumor markers (CA 15-3, CA 27.29, CEA) interpreted together with imaging; a rising marker alone should not change treatment. Tumor markers are not used for surveillance after curative treatment of early breast cancer.
Quick Scenarios
| Scenario | Imaging decision |
|---|---|
| 1.8-cm node-negative cancer, no symptoms | No systemic staging |
| 3-cm cancer with one mobile palpable node (cT2 N1) starting neoadjuvant therapy | Systemic imaging often considered; stage III definitely staged |
| New back pain during adjuvant endocrine therapy | Bone-focused imaging (MRI of the spine if cord compression is possible) |
| Rising liver enzymes on routine labs in a survivor | Abdominal imaging |
| Persistent headaches with nausea on waking | Contrast-enhanced brain MRI |
A 58-year-old woman has a newly diagnosed 1.6-cm ER-positive, HER2-negative invasive ductal carcinoma with a clinically and sonographically negative axilla. She feels well and asks for a PET scan "to make sure it hasn't spread." What is the best response?
Order FDG PET/CT because all breast cancers require whole-body staging.
Order a bone scan because bone is the most common site of metastasis.
Order serum tumor markers every month until surgery.
Explain that routine systemic imaging is not recommended for asymptomatic stage I disease because false positives outnumber true metastases.
Which patient most clearly needs systemic staging imaging before treatment?
A 50-year-old with a 0.8-cm node-negative tubular carcinoma
A 44-year-old with a 6-cm primary tumor and matted ipsilateral axillary nodes (clinical stage IIIA)
A 65-year-old with 2-cm DCIS found on screening
A 39-year-old with a 1.5-cm node-negative HER2-positive cancer and no symptoms
A patient with a tissue expander placed at mastectomy 3 weeks ago is scheduled for a staging breast MRI of the opposite breast. What is the nurse's priority action?
Confirm whether the expander has a magnetic port and notify radiology before the scan, because many expanders are MRI-unsafe.
Proceed, because expanders are made of silicone and are always MRI-safe.
Fill the expander with more saline before the MRI to prevent displacement.
Give gadolinium early so the scan can be shortened.
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