What is the preferred imaging modality, CT (Computed Tomography) scan or MRI (Magnetic Resonance Imaging), for initial evaluation and staging of a patient with maxillary cancer?

Imaging for Maxillary Cancer: MRI is Preferred for Initial Evaluation and Staging

MRI orbits, face, and neck without and with IV contrast is the preferred imaging modality for initial evaluation and staging of maxillary cancer, with CT neck with IV contrast serving as a complementary study for osseous detail. 1

Primary Imaging Recommendation

MRI provides superior soft tissue contrast resolution that is essential for accurate T-staging of maxillary malignancies. 1 The American College of Radiology (ACR) 2023 guidelines specifically recommend MRI orbits, face, and neck without and with IV contrast as the primary imaging study for paranasal sinus and nasal cavity cancers. 1

Why MRI is Superior

• MRI excels at delineating soft tissue extent of disease, which is critical for determining resectability and treatment planning in maxillary tumors 1
• MRI is superior for detecting perineural spread, a common and prognostically important feature in maxillary malignancies that significantly impacts survival 1, 2
• MRI better evaluates tumor margins and soft tissue invasion into adjacent structures including the orbit, pterygopalatine fossa, and infratemporal fossa 3
• MRI demonstrates higher correlation with surgical findings compared to CT in maxillary and mandibular tumors 3

Complementary Role of CT

CT neck with IV contrast should be obtained as a complementary study, not as the sole imaging modality. 1 CT provides specific advantages that MRI cannot match:

• CT is superior for evaluating cortical bone erosion and destruction, which is an upstaging feature in maxillary cancer 1
• CT provides excellent delineation of osseous anatomy and can detect subtle cortical changes 4, 5
• CT is essential for radiation treatment planning due to its precise anatomic detail 1

When to Use CT Maxillofacial

CT maxillofacial (with or without IV contrast) may be appropriate when additional osseous detail is needed beyond what CT neck provides. 1 However, CT maxillofacial alone is inadequate because it typically does not include the entire neck and therefore cannot properly stage regional lymphadenopathy. 1

Complete Staging Protocol

For comprehensive staging of maxillary cancer, the ACR recommends a multimodal approach:

• MRI orbits, face, and neck without and with IV contrast (primary study) 1
• CT neck with IV contrast (complementary for bone detail) 1
• FDG-PET/CT skull base to mid-thigh (complementary for nodal and distant metastases) 1
• CT chest with or without IV contrast (for pulmonary metastases, especially in advanced disease) 1

Critical Pitfalls to Avoid

• Do not rely on CT alone for maxillary cancer staging - CT has inferior soft tissue resolution and may miss perineural spread, which occurs in 26% of maxillary malignancies and significantly worsens prognosis 1, 2
• Do not use CT maxillofacial as the sole imaging study - it will miss nodal disease in the neck, leading to understaging 1
• Do not skip MRI in favor of CT simply for convenience - the superior soft tissue detail of MRI directly impacts surgical planning and treatment decisions 3
• Always use IV contrast with both CT and MRI - contrast is essential for delineating tumor extent and distinguishing tumor from surrounding inflammation 1

Clinical Context

Maxillary sinus cancers are often diagnosed at advanced stages (77.5% present as T4 disease) and frequently demonstrate perineural invasion (49.3% of cases) and lymphovascular invasion (31.2% of cases). 2 These features, which MRI detects better than CT, are independent prognostic factors that influence treatment decisions. 2 The symptoms of maxillary cancer (nasal obstruction, epistaxis, facial swelling) mimic chronic sinusitis, contributing to diagnostic delays. 6 Therefore, when maxillary cancer is suspected, comprehensive imaging with MRI as the primary modality is essential for accurate staging and treatment planning. 1, 3