What imaging study should be ordered for a patient with a palpable skull mass?

Imaging for Palpable Skull Mass

Order a CT head with IV contrast as the initial imaging study for a palpable skull mass, as this provides optimal evaluation of both osseous destruction and soft tissue characteristics while allowing assessment of intracranial extension. 1

Primary Imaging Recommendation

CT head with IV contrast is the preferred initial study because:

• Provides superior spatial resolution for detecting bony destruction, remodeling, or pathological calcification that helps distinguish benign from aggressive lesions 1
• Contrast enhancement is essential for characterizing the soft tissue mass, detecting necrosis, and evaluating the relationship to adjacent vascular structures 1, 2
• Evaluates intracranial extension which is critical for surgical planning and determining the full extent of disease 1
• Rapid acquisition time makes it practical in most clinical settings 1, 3

When to Add MRI

Add MRI head without and with IV contrast in the following scenarios:

• After initial CT confirms a mass requiring detailed soft tissue characterization, as MRI provides superior soft tissue contrast and anatomic detail for treatment planning 1
• When intracranial extension is present, since MRI better delineates brain parenchyma involvement and dural invasion 1
• For vascular lesions, where MRI/MRA can help characterize flow characteristics without radiation 1
• When the CT is equivocal or doesn't fully explain the clinical presentation 3

Key Imaging Features to Assess

The radiologist should evaluate:

• Bone involvement pattern: Lytic destruction suggests aggressive malignancy, while smooth remodeling suggests slow-growing benign lesions 1
• Soft tissue characteristics: Enhancement pattern, presence of necrosis, and relationship to major vessels 1, 2
• Intracranial extension: Dural involvement, brain parenchyma invasion, or mass effect 1
• Calcification or mineralization: May suggest specific diagnoses like osteoma or fibro-osseous lesions 1

Important Caveats

• Dual-phase imaging (without and with contrast) is not usually necessary—proceed directly to contrast-enhanced CT unless there is a specific contraindication 1, 2
• Plain skull radiographs are inadequate for proper evaluation and should not be used as the primary imaging modality 2
• If contrast is contraindicated, non-contrast CT still provides valuable information about bony abnormalities, though soft tissue evaluation will be limited 1, 4
• Most skull base masses require histologic sampling for definitive diagnosis, as imaging features are rarely pathognomonic 1

Clinical Pitfalls to Avoid

• Don't rely on ultrasound for skull masses—it cannot adequately assess bone or deep structures 1
• Don't order MRI first without CT, as you'll miss critical bony detail needed for surgical planning 1
• Don't forget to image the full extent—skull base masses may extend into the nasopharynx, orbit, or intracranial compartment 1, 5