FDG PET/CT superior to CT/MRI in depicting occult neck metastasis

18F-FDG PET/CT performs better than CT/MRI in depicting occult cervical metastatic nodes in patients with negative neck palpitation findings (stage cN0), according to a study published in the April issue of Radiology.

Accurate assessment of cervical nodal metastasis is vital when determining a treatment plan for patients with head and neck squamous cell carcinoma and stage cN0. CT and MRI are commonly used to depict tumor and lymph nodes in head and neck squamous cell carcinomas, but their scopes are constrained. Lead author Jong-Lyel Roh, MD, of the University of Ulsan College of Medicine in Seoul, Korea, and colleagues examined the clinical usefulness of 18F-FDG PET/CT and CT/MRI in detecting occult neck metastasis.

The prospective study included 91 patients with head and neck squamous cell carcinoma and stage cN0 who were assessed with the two types of modalities. Once the diagnostic values of 18F-FDG PET/CT and CT/MRI were compared, the researchers found that 18F-FDG PET/CT more sensitively exhibited nodal metastasis than CT/MRI at 69 percent versus 39 percent.

While 18F-FDG PET/CT had a high sensitivity across all levels, ranging from 63 to 100 percent, PET/CT’s sensitivity was low at almost all levels with a range of zero to 38 percent. Per patient, 18F-FDG PET/CT exhibited a sensitivity of 71 percent and CT/MRI demonstrated a sensitivity of 50 percent.

18F-FDG PET/CT correctly determined occult metastasis in 27 of 38 patients, or 71 percent. CT/MRI, on the other hand, correctly identified cervical metastasis in 19 patients.

Importantly, 18F-FDG PET/CT accurately portrayed CT/MRI false-negative findings in nine of 19 patients. However, it also produced false-negative results in 11 patients. The probability of occult neck metastasis was reduced to 12 percent with 18F-FDG PET/CT.

“Although CT/MR imaging is less sensitive than 18F-FDG PET/CT, it is still required for pretreatment evaluation of primary and neck diseases,” wrote Roh and colleagues. “Improved detection and nodal staging with these modalities may promote appropriate therapeutic planning for patients with stage cN0 HNSCC.”