The association between cumulative radiation dose and the incidence of severe oral mucositis in head and neck cancers during radiotherapy.

BACKGROUND: Quality of life can be influenced by oral mucositis (OM), and it is necessary to implement OM management strategies before the initiation of radiotherapy (RT) in patients with head and neck cancer (HNC). AIMS: To examine the association between the cumulative radiation dose and the incidence of severe OM in HNC patients receiving RT. METHODS AND RESULTS: A retrospective observational cohort study was conducted in a Showa University Fujigaoka Hospital, in Japan. We retrospectively analyzed 94 patients with HNC who developed OM during RT. We defined OM as a more than grade 2 OM. The cumulative incidence of OM curves of the two categories was estimated using the Kaplan-Meier method and compared using the log-rank test. We estimated the hazard ratio (HR) for OM after the adjustment of factors for covariates using Cox's regression analysis. Patients with smoking history had a significantly later development of OM than those with no smoking history (20 Gy-incidence OM 68.7% vs 39.7%, P = .003). In contrast, patients undergoing concurrent chemotherapy had an earlier development of OM than those undergoing RT alone (20 Gy-incidence OM 24.2% vs 55.7%, P < .001). Multivariate analysis revealed that no smoking history and concurrent chemotherapy were independent predictive factors, with a HR of 0.526 (P = .025) and 2.690 (P < .001), respectively. CONCLUSION: We demonstrated that no smoking history and concurrent chemotherapy may be predictive of OM in HNC patients.

[Numerical and Visual Evaluation of Compressed Sensing MRI Using 3D Cartesian Sampling].

We performed numerical and visual evaluation of compressed sensing MRI (CS-MRI) using 3D Cartesian sampling by numerical simulation. Three brain anatomical ROIs (white matter, gray matter, cerebrospinal fluid) of a T1-weighted image (T1WI), a T2-weighted image (T2WI) and a proton density-weighted image (PDWI) were used for numerical evaluation. Sampling ratio of the Cartesian grid was 30%. Reconstruction was performed by the projection onto convex sets (POCS) method with soft thresholding, subject to data fidelity constraints. In the absence of noise, RMSE of 3D-T1WI was 1.50, ant that of the 2D-T1WI of the transverse plane was in the range of 1.06 to 1.54; anatomical ROIs was in the range of 0.75 to 2.80; those of T2WI were 3.20, 2.77 to 3.06, and 1.81 to 4.51; those of PDWI were 1.69, 1.33 to 1.49, and 1.08 to 1.86. Visual evaluation was performed by three radiologists on the basis of three categories: artifact, anatomical structure, and tissue contrast. Average score of the visual evaluation indicated that anatomical structure and tissue contrast of CS images were equal to those of the original image, although a few artifacts were visible. If noise level was assumed to be 20 dB or less, anatomical structure and tissue contrast were not significantly degraded compared to noise-free CS images.

Analysis of the Risk Factors for Severe Oral Mucositis in Head and Neck Cancer after Chemoradiotherapy with S-1.

Radiotherapy (RT) and chemoradiotherapy (CRT) is widely accepted as the standard treatment for head and neck cancer (HNC). Oral mucositis (OM) often develops as an adverse reaction in HNC patients that receive RT or CRT involving S-1. However, little is known about the risk factors for OM in HNC patients. We retrospectively evaluated patients' pre-treatment clinical data in order to identify the risk factors for severe OM in HNC patients that are treated with RT or CRT involving S-1. We analyzed the cases of 129 patients who received RT or CRT involving S-1 for HNC. The endpoint of the survey was the occurrence of severe OM (≥grade 2). Risk factors that were significantly related to severe OM were identified using logistic regression analysis. The patients' mean age was 69.3±10.1 years, and 118 (92%) of the patients were male. The primary tumor was located in the oropharynx in 21.7% of cases. Severe OM occurred in 85.0% of cases. In the univariate analysis, the following variables were found to be associated with severe OM: age, the type of radiotherapy, disease stage, and chemotherapy. In the multivariate analysis, the location of the primary tumor and chemotherapy were identified as significant risk factors that contributed independently to the risk of severe OM (p<0.05). Our analysis suggests that cancer of the oropharynx and CRT are important risk factors for severe OM in HNC patients that undergo RT or CRT involving S-1.

[Numerical and Visual Evaluations of Compressed Sensing MRI Using 2D Radial Sampling].

Two-dimensional radial MRI using compressed sensing (2D radial CS) enables incoherence sampling in k space unlike conventional Cartesian MRI, however 2D radial CS has not been sufficiently investigated. Numerical and visual evaluations of 2D radial CS were performed in this paper. Three brain anatomical ROIs (white matter, gray matter, cerebrospinal fluid) of a T1-weigthted image (T1WI), a T2-weighted image (T2WI) and a proton density-weighted image (PDWI) were used for the numerical evaluation. The Brainweb MRI Data Base was used for test images. Projection of 80 spokes with linear sampling of 256 pixels was used. Reconstruction was performed by minimizing the L1 norm of a transformed image using wavelet transform and spatial finite-differences (total variation), subject to data fidelity constraint. In the absence of noise, the root mean square error (RMSE) of T1WI was in the range of 3.75 to 5.05; that of the anatomical region of interests (ROIs) was in the range of 1.54 to 10.24; those of T2WI were 8.75 to 11.65 and 4.31 to 6.99; and those of PDWI were 3.44 to 4.46 and 1.34 to 3.09. Visual evaluation was performed by three radiologists on the basis of three categories: artifact, anatomical structure, and tissue contrast. Average percent scores of the visual evaluation were 96% for T1WI, 74-81% for T2WI, and 81-89% for PDWI.

[Numerical and Visual Evaluations of Compressed Sensing MRI Using 2D Cartesian Sampling].

This paper describes numerical and visual evaluations of compressed sensing MRI (CS-MRI) using 2D Cartesian sampling by numerical simulation. The BrainWeb MRI Data Base was used for test images. Three brain anatomical ROIs (white matter, gray matter, cerebrospinal fluid) of a T1-weighted image (T1WI), a T2-weighted image (T2WI) and a proton density-weighted image (PDWI) were used for the numerical evaluation. Sampling ratio was 50%. Reconstruction was performed by minimizing the L1 norm of a transformed image using wavelet transform and total variation, subject to data fidelity constraints. The conjugate gradient method was used in the minimization of the object function. In the absence of noise, the root mean square error (RMSE) of T1WI was in the range of 2.99 to 3.57; that of the anatomical region of interests (ROIs) was in the range of 1.77 to 8.53; those of T2WI were 4.72 to 5.65 and 3.28 to 5.54; and those of PDWI were 1.91 to 2.36 and 1.32 to 2.09. Visual evaluation was performed by three radiologists on the basis of three categories: artifact, anatomical structure, tissue contrast. CS image quality was nearly equal to that of the original image, although a few artifacts were visible. If the noise level was assumed to be 30 dB or less, T1-CS image and PD-CS images were not significantly degraded compared to noise-free images.