Can dual-time-point 18F-FDG PET/CT differentiate malignant salivary gland tumors from benign tumors?

OBJECTIVE: The purpose of this study is to evaluate the usefulness of dual-time-point 18F-FDG PET/CT for discriminating between benign and malignant salivary gland tumors. MATERIALS AND METHODS: Dual-time-point FDG PET/CT images of 40 salivary gland tumors (20 benign and 20 malignant) were evaluated retrospectively. The maximum standardized uptake values (SUVmax) in the early and delayed phases and the retention index of each tumor were calculated and compared between benign and malignant tumors by the Mann-Whitney U test. Receiver operating characteristic (ROC) analysis was used to determine the diagnostic accuracy for malignant salivary gland tumors. The correlation between the delayed SUVmax and retention index was analyzed by calculation of the Spearman correlation coefficient. RESULTS: There were no significant differences in the mean early phase SUVmax or mean delayed phase SUVmax between benign and malignant tumors. The mean (±SD) retention index of the malignant tumors was significantly higher than that of the benign tumors (20.1%±10.2% vs 8.5%±12.3%; p=0.006). When the cutoff value of retention index (15.0%) was used, the sensitivity, specificity, and accuracy each was determined to be 75.0%. ROC analysis did not reveal a significant difference in the diagnostic accuracy between the delayed phase SUVmax and retention index (p=0.139). A significant correlation between the delayed phase SUVmax and retention index was observed for the benign salivary gland tumors (r=0.839; p<0.001). CONCLUSION: Dual-time-point FDG PET/CT is not useful for discriminating between benign and malignant salivary gland tumors, because benign tumors also show high FDG uptake, which increases in the delayed phase.

Optimal timing of post-treatment [18F]fluorodeoxyglucose-PET/CT for patients with head and neck malignancy.

OBJECTIVES: The aims of this study were to evaluate the ability of [F]fluorodeoxyglucose (F-FDG)-PET/computed tomography (CT) to identify tumor recurrence, nodal metastases, and distant metastases for surveillance and discuss the optimal timing of F-FDG-PET/CT examination after the completion of treatment for head and neck malignancy. METHODS: A total of 319 patients who underwent a post-treatment F-FDG-PET/CT examination for head and neck malignancy were studied. F-FDG-PET/CT findings were compared with the final diagnosis confirmed by histopathological examinations or clinical and radiological follow-up for at least 6 months. Patients were divided into two groups according to the presence or absence of clinical suspicion of recurrent disease. The diagnostic accuracy of F-FDG-PET/CT was analyzed for each group. Patients were also categorized according to the time interval between the completion of treatment and the post-treatment F-FDG-PET/CT examination. Differences in diagnostic accuracy due to the time interval were also evaluated. RESULTS: The diagnostic accuracy of F-FDG-PET/CT was high for both groups. The overall accuracy of F-FDG-PET/CT performed within 2 months (69%) after the completion of treatment was significantly inferior to that performed after 2 months (93%). CONCLUSION: F-FDG-PET should be performed immediately for patients with clinically suspected recurrent disease. In others, it should be performed at later than 2 months after the completion of the treatment.

Magnetic resonance imaging of temporomandibular joint cyst.

OBJECTIVE: The objective of this study was to evaluate the magnetic resonance imaging (MRI) and clinical findings of 6 cases with synovial or ganglion cysts occurring in the temporomandibular joint (TMJ). STUDY DESIGN: Six patients with histopathologically confirmed TMJ cysts who were examined by MRI were included in this study. Two oral radiologists retrospectively evaluated MR images. RESULTS: MR images revealed a homogeneous well defined mass of the TMJ in all cases. These cysts demonstrated low signal intensity on proton density-weighted (PDW) and homogeneous very high signal on T2-weighted (T2W) images. They were all characteristically continuous with the joint capsule. Regarding clinical features, all 6 patients had some type of TMJ pain. CONCLUSIONS: TMJ cysts were identified as well defined homogeneous masses with low signal intensity on PDW and very high signal on T2W images, and characterized by continuity with the joint capsule. All of the patients with TMJ cysts exhibited some type TMJ pain.

Longitudinal MRI follow-up of rheumatoid arthritis in the temporomandibular joint: importance of synovial proliferation as an early-stage sign.

This article describes longitudinal magnetic resonance imaging (MRI) observations in a patient with rheumatoid arthritis of the temporomandibular joint. The characteristic findings included marked synovial proliferation, which was observed before the onset of severe bone destruction. MRI is considered to provide valuable information for the early detection of rheumatoid arthritis of the temporomandibular joint.

Dual-time-point fluorodeoxyglucose positron emission tomography for diagnosis of cervical lymph node metastases in patients with head and neck squamous cell carcinoma.

OBJECTIVE: The purpose of this study was to evaluate whether dual-time-point fluorodeoxyglucose positron emission tomography/computed tomography image can improve nodal diagnosis in patients with head and neck squamous cell carcinoma (HNSCC). METHODS: One hundred six HNSCC patients were enrolled. Positron emission tomography/computed tomography images were obtained twice: 1 and 2 hours after fluorodeoxyglucose injection. Maximum standardized uptake value (SUVmax) and SUVmax increasing rate (SUV-IR) were compared with the histopathologic findings to determine the optimal cutoff for nodal diagnosis. RESULTS: Using early-phase image, SUVmax ≧ 2.75 was considered as optimal criterion. When using delayed-phase, SUVmax ≧ 3.5 was optimal. There was no significant difference between these criteria. Maximum standardized uptake value IR ≧ 8.0 (10/s) was considered as optimal, although it provided relatively low sensitivity (66%) and specificity (82%). However, combined criterion of SUVmax ≧ 3.5 in delayed-phase or SUV-IR ≧ 8.0 (10/s) significantly improved the specificity (90%) and accuracy (89%) without decreasing the sensitivity (84%). CONCLUSIONS: Using delayed-phase image combined with SUV-IR can improve the nodal diagnosis in HNSCC patients.

[18F]Fluorodeoxyglucose-PET/CT differentiation between physiological and pathological accumulations in head and neck.

OBJECTIVES: The purposes of this study were to evaluate various physiological fluorodeoxyglucose (FDG) accumulations in the head and neck and to compare those with tumor (pathological) FDG accumulation. METHODS: One hundred and twelve patients with head and neck carcinomas were studied. PET/computed tomography examinations were performed 1 h after intravenous injection of fluorine-18-labeled FDG. The tumor and the physiological FDG accumulations were identified with PET/computed tomography images, and the maximum of the standardized uptake value (SUVmax) was calculated. RESULTS: Physiological FDG accumulation was observed in tonsil, extraocular muscle, masticatory muscle, vocal cord, and the major salivary glands: parotid, submandibular, and sublingual gland. The accumulation in tonsil, extraocular muscle, and sublingual gland showed relatively high SUVmax. The tumor FDG accumulation was significantly higher than any physiological FDG accumulation. The optimal cut-off values of SUVmax for differentiating physiological FDG accumulation from pathological FDG accumulation were 4.0 for parotid gland, 4.5 for submandibular gland, 5.5 for sublingual gland, 8.0 for tonsil, and 10.0 for extraocular muscle. The right-to-left ratio of SUVmax was less than 1.5 in any physiological accumulation. CONCLUSION: Tonsil, extraocular muscle, and sublingual gland showed relatively high FDG accumulation, which was sometimes similar to tumor accumulation. The right-to-left ratio of SUVmax was considered useful in differentiating tumor from physiological accumulation, and the presence of tumor might be highly suspected in cases with a ratio of 1.5 or more.

Tissue characterization of head and neck lesions using diffusion-weighted MR imaging with SPLICE.

PURPOSE: The purpose of this study was to evaluate the usefulness of diffusion-weighted (DW) MR imaging with split acquisition of fast spin-echo signals (SPLICE) in the tissue characterization of head and neck mass lesions. PATIENTS AND METHODS: DW MR images of 67 head and neck mass lesions were obtained using SPLICE with b-factors of 0 and 771s/mm(2). The lesions were classified into three categories: 16 cysts, 32 benign tumors, and 19 malignant tumors. After ADC maps were constructed for all lesions, ADC values were calculated and compared among the three categories. RESULTS: No case showed severe image distortion on DW MR imaging with SPLICE, and reliable ADC maps and ADC values were obtained in all cases. The mean ADC value of cysts was 2.41+/-0.48 x 10(-3)mm(2)/s, which was significantly higher than that of benign (1.48+/-0.62 x 10(-3)mm(2)/s) and malignant (1.23+/-0.45 x 10(-3)mm(2)/s) tumors (P<0.001). However, there was no significant difference between the ADC values of benign and malignant tumors (P=0.246). When an ADC value of 2.10 x 10(-3)mm(2)/s or higher was used as the diagnostic criterion for cysts, the sensitivity, specificity, and accuracy were 94%, 88%, and 90%, respectively. CONCLUSION: SPLICE was considered a recommended DW MR imaging technique for the head and neck. Although ADC values were useful in differentiating cysts from tumors, they contributed little in predicting malignancy.

Diagnostic accuracy of cone-beam CT in the assessment of mandibular invasion of lower gingival carcinoma: comparison with conventional panoramic radiography.

PURPOSE: To evaluate the diagnostic accuracy of cone-beam CT in assessing mandibular invasion by lower gingival carcinoma and compare it with that of panoramic radiography. PATIENTS AND METHODS: Fifty patients with squamous cell carcinoma of the lower gingiva who were examined by both panoramic radiography and cone-beam CT before surgery were included in this study. Five radiologists used a 6-point rating scale to independently evaluate cone-beam CT and panoramic images for the presence or absence of alveolar bone and mandibular canal involvement by tumor. Using the histopathogical findings as the gold standard, we calculated and compared the area under the receiver operating characteristic curve (Az value) and the sensitivity and specificity of the two imaging modalities. RESULTS: In evaluations of both alveolar bone and mandibular canal involvement, the mean Az value for cone-beam CT (0.918 and 0.977, respectively) was significantly higher than that for panoramic radiography (0.793 and 0.872, respectively). The mean sensitivity for cone-beam CT (89% and 99%, respectively) was significantly higher than that for panoramic radiography (73% and 56%, respectively). There was no significant difference in the mean specificity. While cone-beam CT could provide high-resolution three-dimensional images, the image quality around the alveolar crest was often hampered by severe dental artifacts and image noise, resulting in difficulties in detecting subtle alveolar invasion. CONCLUSION: Cone-beam CT was significantly superior to panoramic radiography in evaluating mandibular invasion by lower gingival carcinoma. Its diagnostic value in detecting subtle alveolar invasion, however, may be limited by severe dental artifacts and image noise.

MRI findings of temporomandibular joints with disk perforation.

OBJECTIVE: To investigate magnetic resonance imaging (MRI) findings of temporomandibular joints (TMJs) with disk perforation. STUDY DESIGN: Thirty-one TMJs (31 patients) with disk perforation, 37 TMJs (34 patients) with anterior disk displacement and no disk perforation, and 22 asymptomatic TMJs of 11 volunteers were examined by MRI. The presence or absence of disk perforation was confirmed by TMJ arthrography. The MR images were evaluated for the presence or absence of disk deformity, disk displacement, condylar bone changes and joint effusion and for visualization of the temporal posterior attachment (TPA) of the posterior disk attachment. Those findings were compared among the 3 groups. RESULTS: The incidences of anterior disk displacement and condylar bone changes in the patients group with disk perforation were significantly higher than in asymptomatic volunteers. Disk deformity and obscurity of TPA were significantly more frequent in the patient group with disk perforation than in the other 2 groups. CONCLUSION: In addition to disk deformity, TPA obscurity was considered to be one of the characteristic MRI findings of TMJs with disk perforation.

MRI and clinical findings of posterior disk displacement in the temporomandibular joint.

OBJECTIVE: The objective of this study was to evaluate the magnetic resonance imaging and clinical findings of patients with posterior disk displacement in the temporomandibular joint. STUDY DESIGN: Magnetic resonance and clinical findings of 62 temporomandibular joints (44 patients) with posterior disk displacement were retrospectively analyzed. RESULTS: According to the criteria proposed by Westesson et al., 52 temporomandibular joints (84%) were the thin flat disk type and the remaining 10 (16%) were the perforated disk type. Fifteen temporomandibular joints (24%) had a history of luxation. Clicking was observed in 26 temporomandibular joints (42%), all of which were the thin flat disk type (chi-square test, P < .01). Pain was observed in 19% of patients with the thin flat disk type and 60% of those with the perforated disk type (P < .05). CONCLUSIONS: Magnetic resonance imaging could clearly reveal the details of posterior disk displacement in the temporomandibular joint. The clinical findings were dissimilar between the thin flat and the perforated disk type.

[Role of insulin-like growth factor-I receptor (IGF-IR) in survival kinetics and radioresistance of mouse embryo fibroblasts in a hypoxic environment].

The role of insulin-like growth factor-I receptor (IGF-IR) in survival kinetics and radioresistance of fibroblasts in a severely hypoxic environment (partial oxygen pressure of less than 3 mmHg) was analyzed, in both low and high cell-density conditions. Mouse embryonic fibroblasts R(-), with a targeted disruption of the IGF-IR gene, and R(+) cells, derived from R(-) cells stably transfected with a plasmid containing a human IGF-IR cDNA, were used for this purpose. Survival time in hypoxia was longer in R(+) cells than R(-) cells, which correlated with highly elevated expression of caspase 3-like activity in R(-) cells, but not with HIF-I alpha expression. Under euoxia, R(+) cells were more radioresistant, by a factor of 1.9, than R(-) cells. Under hypoxia, R(+) cells became more radioresistant, with an oxygen-enhancement ratio (OER) of 2.7, than R(-) cells, with an OER of 1.5, in a low cell density. However, unexpected hyper-radiosensitivity in hypoxia was observed for both R(+) and R(-) cells in a high cell density, which further increased with incubation time in hypoxia following X-irradiation. The hyper-radiosensitivity was more pronounced for R(-) cells. The result thus implies that IGF-IR may be an important target molecule for radioresistant tumors in radiotherapy.