Non-linear image blending improves visualization of head and neck primary squamous cell carcinoma compared to linear blending in dual-energy CT

•Non-linearly blended and linearly blended images series of DECT were compared.•Non-linear blending provides superior tumor attenuation and contrast-to-noise ratio of head and neck squamous cell carcinoma.•Non-linear blending provides superior subjective tumor delineation and improved overall image quality compared to linear blending.•Non-linearly blended image series may facilitate assessment of tumor infiltration of surrounding anatomic structures.

AimTo compare non-linear and linear image-blending post-processing techniques in dual-energy CT (DECT) of primary head and neck squamous cell carcinoma (SCC) regarding subjective and objective image quality.Materials and methodsHead and neck DECT studies from 69 patients (48 male, 21 female; mean age 62.3 years) were retrospectively evaluated. All tumour lesions were histologically confirmed SCC. Linearly blended 80/140 kVp images series with varying weighting factors of 0.3 (M_0.3), 0.6 and 0.8 were compared with non-linearly blended images. Attenuation of tumour lesion, various soft-tissue structures, the internal jugular vein, and image noise were measured, tumour signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Overall image quality, delineation of tumour lesion, image sharpness, and noise level were rated individually by three radiologists using five-point Likert scales. Interobserver agreement was calculated using intraclass correlation coefficient (ICC).ResultsEnhancement of tumour lesions (non-linear, 137.5 ± 20.1 HU; M_0.3, 92.7 ± 14.4 HU; M_0.6, 110 ± 15.4 HU; M_0.8, 123 ± 18.2 HU), CNR (non-linear, 12 ± 8; M_0.3, 4 ± 4.7; M_0.6, 7.5 ± 5.5; M_0.8, 8 ± 5.5), subjective overall image quality and tumour delineation were significantly increased (all p < 0.001) with the non-linear blending technique compared to all investigated linear blending weighting factors. Overall interobserver agreement was substantial (ICC 0.70; 95% CI: 0.66-0.73).ConclusionPost-processing of DECT using a non-linear blending technique provides improved objective and subjective image quality of head and neck SCC compared to linearly blended images series.