Feasibility study of reduced field of view diffusion-weighted magnetic resonance imaging in head and neck tumors

Background: Reduced field of view (rFOV) imaging may be used to improve the quality of diffusion-weighted imaging (DWI) in the head and neck (HN) region. Purpose: To evaluate the feasibility of rFOV-DWI in patients affected by HN tumors, through a comparison with conventional full FOV (fFOV) DWI. Material and Methods: Twenty-two patients with histologically-proven malignant or benign tumors of the head and neck were included in a retrospective study. All patients underwent pre-treatment magnetic resonance imaging (MRI) studies including rFOV-DWI and fFOV-DWI. The apparent diffusion coefficient (ADC) value distributions inside tumor and muscle were derived and the mean, standard deviation (SD), and kurtosis were calculated. Image distortion was quantitatively and qualitatively evaluated, as well as the capability of lesion identification. The Wilcoxon test was used to compare all variables. Agreements between the ADC estimations were assessed by Bland-Altman plots. Results: Image distortion and lesion identification scores were both higher for rFOV-DWI compared to fFOV-DWI. A reduction in ADC values with rFOV-DWI emerged for both lesion and muscle, with a mean percentage difference in ADC of 6.2% in the lesions and 24.9% in the muscle. The difference in SD of ADC was statistically significant in the lesions, indicating a higher ADC homogeneity for rFOV DWI (P = 0.005). Conclusion: The application of rFOV DWI in patients affected by HN tumors is feasible and promising, based on both qualitative and quantitative analyses. This technique has potential for improving the diagnostic accuracy of fFOV-DWI for the study of specific tumoral areas.