Correlation of 3T Magnetic Resonance Imaging Neurogram to Histology for Large Nerve Perineural Spread From Cutaneous Squamous Cell Carcinoma of the Head and Neck

ABSTRACT Introduction Cutaneous Squamous Cell Carcinoma (cSCC) is a major health issue in Australia. Perineural spread (PNS) in cSCC carries a worse prognosis. Magnetic Resonance Imaging (MRI) neurogram is the best imaging modality to detect and define the zonal extent of PNS, although histology remains the diagnostic gold standard. Aims Investigate the agreement between the detection of PNS on MRI and the histology of the resected nerve. We also assess the agreement of MRI zoning with the histological zoning based on William's definition and our department's modified classification system. Methods We conducted a retrospective review of consecutive patients with PNS from cSCC of the head and neck. Patients included had PNS on MRI neurogram and histology of the suspected nerve for review. Results Seventy patients were included, with 90 suspected involved nerves reviewed. Two nerves considered involved with PNS on MRI were not involved on histology. The positive predictive value of MRI neurogram was 98%. Three nerves were negative on MRI but positive on histology, resulting in a 97% positive agreement. The observed zonal agreement was 83% based on William's zonal classification and 69% with our institution's modified zonal classification system. With the latter system, the agreement for zones 1, 2a and 2b PNS was 85%, 50% and 40% respectively. Conclusion 3T MRI neurogram is an effective modality to detect PNS in cSCC of the head and neck region. The accuracy of MRI to sub‐define zones 2a and 2b requires further study.