Background: The purpose of this study was to assess whether apparent diffusion coefficient (ADC) values of esophageal squamous cell carcinoma (ESCC) predict responses to chemoradiotherapy (CRT) and/or patient prognosis. Methods: Magnetic resonance images were acquired to construct the diffusion-weighted images, and the ADC values were calculated before CRT in 80 patients with ESCC. A high-ADC group responded better to CRT than did a low-ADC group (p < 0.01). We divided the 80 patients into two groups based on the operating characteristic analysis: one group comprised patients with ADC values higher than the average ADC of the esophageal cancer tissue (1.10 × 10^–3 mm²/s), and the other group comprised those whose ADC values were less than the average value. A Kaplan-Meier analysis showed that the survival rate in the high-ADC group was significantly better than that in the low-ADC group (p = 0.04). Conclusion: Our results indicate that the ADC value may be a useful marker to predict treatment response as well as survival for patients with ESCC.

Positron emission tomography (PET) with 2-[fluorine-18] fluoro-2-deoxy-d-glucose (FDG) may play an important role in the evaluation and management of malignant lymphoma. FDG uptake is predictive of therapeutic response during the course of treatment. After completion of chemotherapy, residual abnormalities representing either residual tumor or necrotic or fibrotic tissue are not uncommon, and FDG PET may be more accurate than computed tomography (CT) or magnetic resonance imaging in assessing residual disease and identifying patients who require more intense treatment. However, posttreatment FDG PET does not help exclude the presence of minimal residual disease, which may lead to disease relapse. Furthermore, FDG is not a tumor-specific substance, and increased accumulation may be seen in a variety of benign entities and scenarios (eg, infection, drug toxicity, granulocyte colony-stimulating factor therapy, radiation therapy, physiologic activity, postoperative or postbiopsy changes, fracture, degenerative change, injection leakage), which may yield false-positive findings. Nevertheless, recognition of these entities and correlation of FDG PET findings with clinical and other radiologic findings-especially those at combined PET and CT or PET-CT fusion imaging-allows improved diagnostic accuracy. If the interpretation of positive findings is exceptionally difficult, short-term follow-up may be helpful.

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Although the diagnostic value of FDG PET in the differentiation of malignant from benign parotid gland tumors was limited because of the high FDG uptake in some benign tumors, and particularly pleomorphic adenomas, combining salivary gland scintigraphy with FDG PET may help to negate this drawback, and this combination may be a more promising approach for differentiation of various parotid gland tumors in patients compared with nondiagnostic needle aspiration.

ADC measurement of the left hepatic lobe was far more incorrect than that of the right lobe if cardiac gating was not employed. The administration of Buscopan worsened the image quality of the left lobe and made visual evaluation difficult.