What is the most appropriate initial imaging order for a 65-year-old patient with a history of breast cancer (Carcinoma of the breast) presenting with a persistent headache and clumsiness in her right leg?

MRI Head Without and With IV Contrast Should Be Ordered

In a 65-year-old patient with a history of breast cancer presenting with persistent headache and focal neurological symptoms (right leg clumsiness), MRI head without and with IV contrast is the most appropriate initial imaging study to evaluate for brain metastases. 1

Clinical Reasoning

This patient is symptomatic with neurological complaints (headache plus focal motor dysfunction), which fundamentally changes the imaging approach:

• The ACR Appropriateness Criteria explicitly state that MRI head without and with IV contrast is "usually appropriate" for patients with suspected distant recurrence of breast cancer based on symptoms, physical examination, or laboratory values, regardless of clinical stage at original presentation. 1

• The combination of persistent headache with focal neurological deficits (right leg clumsiness) in a patient with breast cancer history raises significant concern for brain metastases, which occur in approximately 9-11% of breast cancer patients. 1

• CT head (Option B) is inferior to MRI for detecting brain metastases and parenchymal lesions. While CT is appropriate for acute trauma or hemorrhage, MRI is more sensitive for all posttraumatic and metastatic lesions except skull fracture and subarachnoid hemorrhage. 2

Why Other Options Are Incorrect

MRI Breast (Option A)

• MRI breast is appropriate for evaluating local recurrence in the breast tissue itself, not for neurological symptoms. 1
• This patient's symptoms are neurological, not related to breast tissue changes. 1

CBC and BMP (Option C)

• While laboratory studies may be part of a comprehensive workup, they do not provide the critical imaging needed to identify brain metastases causing focal neurological deficits. 1
• Delaying definitive imaging in favor of laboratory studies alone would be inappropriate when brain metastases are suspected. 1

Lumbar Puncture (Option D)

• LP has no role in the initial evaluation of suspected brain metastases. 1
• LP would be contraindicated if a mass lesion is present due to risk of herniation.
• Imaging must precede LP in any patient with focal neurological deficits.

Important Clinical Distinctions

Symptomatic vs. Asymptomatic Surveillance:

• The ACR guidelines explicitly state that imaging is "usually not appropriate" for distant disease surveillance in asymptomatic patients with breast cancer history. 1
• However, this patient is symptomatic with both headache and focal motor deficits, making her a candidate for comprehensive metastatic workup. 1

Comprehensive Metastatic Evaluation

While MRI head is the priority given the neurological symptoms, the ACR guidelines recommend that symptomatic patients may benefit from complementary imaging studies: 1

• Bone scan whole body (for skeletal metastases, the most common site at 51%) 3
• CT chest, abdomen, and pelvis with IV contrast (for visceral metastases) 1
• FDG-PET/CT skull base to mid-thigh (can be used in symptomatic patients per NCCN guidelines) 1

These are complementary studies that provide unique clinical information, but MRI head addresses the immediate clinical concern of focal neurological deficits. 1

Critical Pitfall to Avoid

Do not order CT head instead of MRI brain in this scenario. CT has significantly lower sensitivity for detecting brain metastases compared to contrast-enhanced MRI, and may miss small parenchymal lesions that are causing the patient's symptoms. 2 The only scenario where CT head would be appropriate as initial imaging is in acute trauma or when MRI is contraindicated or unavailable.