Simultaneous 18F-FDG-PET/MRI: Associations between diffusion, glucose metabolism and histopathological parameters in patients with head and neck squamous cell carcinoma

• There are different significant correlations between DWI, PET and histopathological parameters in squamous cell carcinoma of head and neck.
• ADC and SUV values can be used as biological markers in squamous cell carcinoma of head and neck.

SummaryObjectivesTo analyze possible associations between functional simultaneous 18F-FDG-PET/MR imaging parameters and histopathological parameters in head and neck squamous cell carcinoma (HNSCC).Material and Methods11 patients (2 female, 9 male; mean age 56.0 years) with biopsy-proven primary HNSCC underwent simultaneous 18F-FDG-PET/MRI with a dedicated head and neck protocol including diffusion weighted imaging. For each tumor, glucose metabolism was estimated with standardized uptake values (SUV) and diffusion restriction was calculated using apparent diffusion coefficients (ADC).The tumor proliferation index was estimated on Ki 67 antigen stained specimens. Cell count, total nucleic area, and average nucleic area were estimated in each case. Pearson’s correlation coefficient was used to analyze possible associations between the estimated parameters.ResultsThe mean SUVmax value was 24.41 ± 6.51, and SUVmean value 15.01 ± 4.07. Mean values (×10−3 mm2 s−1) of ADC parameters were as follows: ADCmin: 0.65 ± 0.20; ADCmean: 1.28 ± 0.18; and ADCmax: 2.16 ± 0.35. Histopathological analysis identified the following results: cell count 1069.82 ± 388.66, total nucleic area 150771.09 ± 61177.12 μm2, average nucleic area 142.90 ± 57.27 μm2 and proliferation index 49.09 ± 22.67%. ADCmean correlated with Ki 67 level (r = −0.728, p = 0.011) and total nucleic area (r = −0.691, p = 0.019) and tended to correlate with average nucleic area (r = −0.527, p = 0.096). ADCmax correlated with Ki 67 level (r = −0.633, p = 0.036). SUVmax also tended to correlate with average nucleic area (r = 0.573, p = 0.066). Combined parameter SUVmax/ADCmin correlated with average nucleic area (r = 0.627, p = 0.039).ConclusionADC and SUV values showed significant correlations with different histopathological parameters and can be used as biological markers in HNSCC.