Predictive Value of Diffusion, Glucose Metabolism Parameters of PET/MR in Patients With Head and Neck Squamous Cell Carcinoma Treated With Chemoradiotherapy

Abstract

Purpose: This study aims to evaluate the predictive value of the pretreatment, metabolic, and diffusion parameters of a primary tumor assessed with PET/MR on patient clinical outcomes. Methods: Retrospective evaluation was performed using PET/MR image data sets acquired using the single tracer injection dual imaging of 68 histologically proven head and neck cancer patients 4 weeks before receiving definitive chemoradiotherapy (CRT). PET/MR was performed before the CRT and 12 weeks after the CRT for response evaluation. Image data (PET and MRI diffusion-weighted imaging [DWI]) was used to specify the maximum standard uptake value, the peak lean body mass corrected, SUV max , the metabolic tumor volume, the total lesion glycolysis (SUV max , SUL peak , MTV, and TLG), and the mean apparent diffusion coefficient (ADC mean ) of the primary tumor. Based on the results of the therapeutic response evaluation, two patient subgroups were created: one with a viable tumor and another without. Metabolic and diffusion data, from the pretreatment PET/MR and the therapeutic response, were correlated using Spearman's correlation coefficient and Wilcoxon's test. Results: After completing the CRT, a viable residual tumor was detected in 36/68 (53%) cases, and 32/68 (47%) patients showed complete remission. However, no significant correlation was found between the pretreatment parameter, ADC mean ( p = 0.88), and the therapeutic success. The PET parameters, SUV max and SUL peak , MTV, and TLG ( p = 0.032, p = 0.01, p < 0.0001, p = 0.0004) were statistically significantly different between the two patient subgroups. Conclusion: This study found that MRI-based (ADC mean ) data from FDG PET/MR pretreatment could not be used to predict therapeutic response although the PET parameters SUV max , SUL peak , MTV, and TLG proved to be more useful; thus, their inclusion in risk stratification may also be of additional value.

Correlation between Tissue Cellularity and Metabolism Represented by Diffusion-Weighted Imaging (DWI) and 18F-FDG PET/MRI in Head and Neck Cancer (HNC)

“…The work strategy and procedure have been published elsewhere [11,12,21]. In brief, the examinations were conducted in a dedicated PET/MRI (3 T) equipment (Biograph mMR, Siemens AG, Erlangen, Germany).…”

“…PET/MRI parameters were also included (ADC, SUV, TLG, and MTV). MRI sequences were T2-weighted TSE turbo inversion recovery magnitude (TIRM) (TR/TE/TI 3300/37/220 ms, FOV: 240 mm, slice thickness: 3 mm, 224 × 320) coronal plan, T1-weighted turbo spin-echo (TSE) (TR/TE 800/12 ms, FOV: 200 mm, slice thickness: 4 mm, 224 × 320), and T1-weighted TSE Dixon fat suppression (FS) (TR/TE 6500/85 ms, FOV: 200 mm, slice thickness: 4 mm, 256 × 320) transversal and were acquired without an intravenous contrast agent [11,12,21].…”

“…All methods of image analysis were previously published [11,12,21]. In short, a fixed 2.5 threshold of SUV was used for tumor SUVmax for both MTV and TLG, as proposed by Pak et al [13].…”

“…In short, a fixed 2.5 threshold of SUV was used for tumor SUVmax for both MTV and TLG, as proposed by Pak et al [13]. DWI measurements were previously mentioned [12,21]. 'Avg' represents the average ADC values for all voxels within the ROI and 'Dev' Represents the standard deviation, see Figure 1.…”

“…Owing to their ability to quantify glucose metabolism in tumors, FDG uptake values from PET imaging play an essential role in head and neck imaging, [12,13], which may also reflect the tumor's aggressiveness and the risk of metastasis spreading to surrounding structures [14,15]. SUV is the most used metric to estimate glucose metabolism, and it has shown promise for predicting the presence of metastatic lymph nodes at the original assessment, as well as survival and recurrence [16].…”