Imaging findings of arrested pneumatisation and differentiation from other skull base lesions.

OBJECTIVES: Arrested pneumatisation (AP) is an anatomic variant of the sphenoid sinus. Since AP remains underrecognised, otolaryngologists and radiologists may mistake AP for a lesion and perform follow-up imaging studies. We investigated the imaging findings of CT, MRI, and F-18 fludeoxyglucose (FDG)-positron emission tomography (PET) for AP, and discussed the differences between AP and other skull base lesions. METHODS: We reviewed multidetector low CT imaging of 442 patients (285 men and 157 women; age range, 19-93 years; mean age, 67.8 years) who underwent FDG-PET/CT for head and neck tumours between January 2019 and December 2019. The imaging findings of AP were reviewed on CT, MRI, FDG-PET/CT, and compared with those of fibrous dysplasia, chordoma, chondrosarcoma, multiple myeloma, and bone invasion of nasopharyngeal carcinoma. RESULTS: AP was identified in 22 patients (14 men and 8 women; age range, 24-93 years; mean age, 67.0 years) based on criteria from previous reports. AP manifested with well-circumscribed sclerotic margins on CT, without evidence of expansion. AP showed high-signal intensity on T1-/T2 weighted MRI. FDG-PET revealed non-significant uptake [maximum standardised uptake value (SUVmax): 0.85 (range, 0.4-1.27)] in AP. Contrastingly, skull base lesions showed expansion, poorly circumscribed boundaries without osteosclerotic margins, and moderate-to-severe FDG uptake (SUVmax: 1.8-8.4). CONCLUSIONS: The characteristic imaging findings of AP, namely non-expansile on CT and non-uptake on FDG-PET, may aid in its differentiation from other skull base lesions.

Evaluation of radiation dose and image quality for dental cone-beam computed tomography in pediatric patients.

Children are sensitive to radiation; therefore, it is necessary to reduce radiation dose as much as possible in pediatric patients. In addition, it is crucial to investigate the optimal imaging conditions as they considerably affect the radiation dose. In this study, we investigated the effect of different imaging conditions on image quality and optimized the imaging conditions for dental cone-beam computed tomography (CBCT) examinations to diagnose ectopic eruptions and impacted teeth in children. To achieve our aims, we evaluated radiation doses and subjective and objective image quality. The CBCT scans were performed using 3D Accuitomo F17. All combinations of a tube voltage (90 kV), tube currents (1, 2, 3 mA), fields of view (FOVs) (4 × 4, 6 × 6 cm), and rotation angles (360°, 180°) were used. Dose-area product values were measured. SedentexCT IQ cylindrical phantom was used to physically evaluate the image quality. We used the modulation transfer function as an index of resolution, the noise power spectrum as an index of noise characteristics, and the system performance function as an overall evaluation index of the image. Five dentists visually evaluated the images from the head-neck phantom. The results showed that the image quality tended to worsen, and scores for visual evaluation decreased as tube currents, FOVs and rotation angles decreased. In particular, image noise negatively affected the delineation of the periodontal ligament space. The optimal imaging conditions were 90 kV, 2 mA, 4 × 4 cm FOV and 180° rotation. These results suggest that CBCT radiation doses can be significantly reduced by optimizing the imaging conditions.

Root canal narrowing patterns of mandibular first premolars on panoramic radiographs according to the number of root canals diagnosed on cone beam computed tomographic images.

Understanding the variations in root canal morphology is important for successful endodontic treatment. Mandibular first premolars have a single root in 98% of cases, and multiple root canals are found in approximately 20% of cases. However, the details of these characteristic findings in panoramic radiography and their diagnostic accuracy are unknown. This study aimed to investigate the characteristic radiographic findings of mandibular first premolars possessing multiple root canals and determine the diagnostic accuracy using panoramic radiography. Four radiologists evaluated 347 mandibular first premolars in 186 patients who underwent panoramic radiography and dental cone beam computed tomography (CBCT). Two radiologists confirmed the existence of single or multiple root canals using CBCT. The remaining two radiologists evaluated the imaging findings of the root canal morphology and classified them into two patterns: gradual narrowing and sudden narrowing. In the case of the sudden narrowing pattern, the location of sudden narrowing was also evaluated. A gradual narrowing pattern was observed in 56% of teeth with a single root canal, and a sudden narrowing pattern was observed in 83% of teeth with multiple root canals. When sudden narrowing between the cervical and apical 1/4 of the root canal was used as the diagnostic criterion for multiple root canal teeth, the highest diagnostic performance was observed (sensitivity, 76.1%; specificity, 73.9%). The sudden narrowing between the cervical level and the apical 1/4 level of the root canal is a practical diagnostic criterion for mandibular first premolar with multiple root canals.

Condylar Resorption Following Compressive Mechanical Stress in Rabbit Model - Association of Matrix Metalloproteinases.

BACKGROUND/AIM: Idiopathic condylar resorption (ICR) is a morphological change of the condylar head that occurs following orthodontic treatment or orthognathic surgery. This complication is serious, as it can cause relapse after mandible treatment. The aim of this experimental study was to evaluate the mechanism of influence of condylar resorption on compressive mechanical stress in temporomandibular joint following a change in occlusal position by mandible advancement. MATERIALS AND METHODS: An osteotomy procedure at the midline of mandible was performed in 15 rabbits, with the left side moved forward by 3.5 mm. Advancement of the left side of the mandible resulted in compressive mechanical stress on condylar head on the left side. Samples were subjected to micro-computed tomography, histological staining and immunohistochemistry. RESULTS: The area and depth of anterior condylar resorption at two weeks were significantly different as compared to those at one week (p<0.05). TRAP staining confirmed the significantly largest number of TRAP-positive cells after two weeks (p=0.02), compared to one week. MMP-3 and MMP-13 immunostaining of the anterior condylar head at two weeks revealed high levels of both proteins from the surface to the deep layer of cartilage. CONCLUSION: Compressive mechanical stress following mandible advancement results in load on the anterior surface of the condylar head, which leads to bone resorption there, and induces MMP-3 and MMP-13 related to degradation of condylar head cartilage.

Effectiveness of an actuator-driven pulsed water jet for removal of softened carious dentin.

The aim of this study was to assess the utility of an actuator-driven pulsed water jet (ADPJ) as a hardness-dependent carious dentin removal device by using different outputs. Thirty-six plane surface dental caries samples were treated with the ADPJ at 150, 200, and 250 voltage (12 teeth each). The Knoop hardness number (KHN) and Ca/P mass ratio were measured at 70 µm from the deepest point of the removing groove. Furthermore, three other teeth samples were manually treated with the ADPJ at the three above mentioned voltages (one tooth each) for 1 min. The KHN and Ca/P mass ratio were measured at 70 µm from the surface of the residual dentin part. In both the KHN and Ca/P mass ratio, higher residual dentin depended on the applied voltage of ADPJ. The ADPJ enabled the removal of softened carious dentin in an applied voltage-dependent manner.

Perfusion defects in non-enlarged metastatic lymph nodes using vessel wall magnetic resonance imaging: Detection performance and diagnostic value.

A perfusion defect (PD) in non-enlarged lymph nodes (LNs) of oral squamous cell carcinoma (OSCC) is the most reliable radiological criterion for the diagnosis of metastasis. However, conventional contrast-enhanced (CE) T1 weighted images using turbo spin echo (TSE) sequence is limited in detecting PD in non-enlarged LNs due to flow artifacts from cervical blood vessels. Vessel wall (VW) MR imaging with blood vessel flow suppression and high spatial resolution may provide new insights into the detection of PD. However, there are no reports in the literature on the usefulness of VW MR imaging for the diagnosis of LN metastasis. It is demonstrated that PD of non-enlarged LNs in CE VR MR imaging of OSCC patients is useful for the diagnosis of metastatic LNs. VW MR imaging was significantly more sensitive in detecting PD of non-enlarged metastatic LNs than conventional TSE imaging on visual evaluation. Furthermore, it was found that the image contrast between PD and surrounding intranodal tissue in CE VW MR images was higher than that in conventional CE TSE images. In the correlation between imaging and histopathological findings of metastatic LNs, all LNs that exhibited PD on CE VW MR images were at an advanced histopathological metastatic stage. The pathology of PD was necrotic tissue with keratinization. The results indicated that PD in CE VW imaging is useful in diagnosing non-enlarged LNs at an advanced metastasis stage. The addition of VW MR imaging to conventional MR examination achieves higher diagnostic performance for non-enlarged metastatic LNs.

Impact of Dental Referral Prior to Elective Surgery on Postoperative Outcomes.

OBJECTIVES: Oral bacteria may contribute to postoperative infectious complications including postoperative pneumonia or surgical site infection. The aim of this study was to investigate the impact of preoperative dental care on postoperative outcomes among surgical patients under general anesthesia. DESIGN: Retrospective cohort study. SETTING AND PARTICIPANTS: We analyzed clinical records of major surgical patients at a university hospital between 2016 and 2018. Subjects were categorized into either the preoperative dental care group, those being referred to dentists by their surgeons based on an individual surgeon's judgment for dental care before surgery, or the control group. METHODS: The primary outcome was postoperative infectious complications. Secondary outcomes were postoperative inflammation markers (C-reactive protein and fever), and economic outcomes (postoperative length of hospital stay and medical expenses). As the main analysis, the average treatment effects of the preoperative dental care were obtained from the augmented inverse-probability weighting (AIPW) method with consideration of demographics and perioperative risk factors to estimate causal effect of the intervention from the observational data. Then, stratified analyses by age and surgical sites were conducted with the inverse-probability weighting and linear regression methods, respectively. RESULTS: In the AIPW estimation, compared with the control group, the care group saw a significantly lower rate of postoperative infection (average treatment effect -3.02) and shorter fever duration (-2.79 days). The stratified analysis by age revealed significant positive impact of dental care in all age groups, including the highest treatment effects observed among patients younger than 60. Also, treatment effect was observed in wider surgical sites than previously known. CONCLUSION/IMPLICATIONS: This study indicates a significant impact of preoperative dental care on preventing postoperative infection and inflammation. Along with old age or certain types of surgeries in which advantages of dental referral have been already known, preoperative dental referral could be beneficial for broader types of patients.

High diagnostic accuracy for lymph node metastasis of oral squamous cell carcinoma using PET/CT with a silicon photomultiplier.

OBJECTIVE: The higher sensitivity of the new-generation positron emission tomography/computed tomography (PET/CT) with silicon photomultiplier (SiPM) may increase false-positive rates in detecting metastatic lymph nodes (LNs). This study aimed to clarify the usefulness of the SiPM PET scanner in diagnosing LN metastasis of oral squamous cell carcinoma (SCC). METHODS: We retrospectively reviewed consecutive F-18 fluorodeoxyglucose PET/CT images of 39 SCC patients using SiPM PET and 31 SCC patients using non-SiPM PET. We measured the maximum standardized uptake value (SUVmax) of the LNs on PET images and maximum short-axis diameter on transverse CT images. RESULTS: The sensitivity and specificity of SiPM PET were 86.2% and 95.6%, respectively (cut-off SUVmax, 4.6). The area under the curve (AUC) of SiPM PET (0.977; 95% confidence interval [CI], 0.958-0.995) was significantly higher than that of non-SiPM PET (0.825; 95% CI 0.717-0.934) (P < 0.01). In a size-limited analysis of diameter, the AUC of SiPM PET (≥ 0.96 for all diameters) was significantly higher than that of non-SiPM PET (tended to decrease as the LN diameter decreased) for the diagnosis of LN metastasis by SUVmax. CONCLUSION: SiPM PET had higher diagnostic accuracy for LN metastasis of oral SCC than non-SiPM PET, even for small LN metastasis without increasing false-positives.

Molecular imaging in masseter muscle observed by muscle function magnetic resonance imaging and 31 P-magnetic resonance spectroscopy in patients with a jaw deformity.

BACKGROUND: Skeletal mandibular protrusion would influence to the muscle fatigue of the masticatory muscles. Establishing a diagnostic procedures combining physiological and biochemical information is necessary for quantitative evaluation of masticatory muscle fatigue. OBJECTIVE: The transverse relaxation time (T2 time) of muscle functional magnetic resonance imaging (mfMRI), and 31 P-magnetic resonance spectroscopy (MRS) were used to investigate the reliability as parameters for measuring the masseter muscle in patients with skeletal mandibular prognathism. METHOD: The subjects were 19 patients diagnosed as skeletal mandibular protrusions and 19 healthy subjects as a control group. Transverse relaxation time (T2 value) determined by mfMRI along with creatine phosphate (PCr) and inorganic phosphorus (Pi) determined by 31 P-MRS before, during, and after clenching were used for molecular imaging of muscle fatigue. RESULTS: The average T2 value of the patient group was significantly higher than that of the healthy control group at rest. Furthermore, the average T2 value transiently increased in both groups during experimental clenching. The PCr and Pi showed a tendency toward a transient decrease and increases, respectively. The pH in the masseter muscle showed a transient decrease in both groups prior to and following experimental clenching. The pH in the masseter muscle of the patient group was significantly lower than that in the healthy control group at rest and recovery. CONCLUSION: We showed mfMRI and 31 P-MRS are useful for evaluating masseter fatigue during clenching, and the masseter muscle in the prognathic patients showed more severe fatigue than the healthy controls.

A comparative study on cephalometric differences in maxillofacial morphology between skeletal Class III cases with and without acromegaly: a pilot study.

OBJECTIVES: The most typical maxillofacial feature of patients with acromegaly is mandibular protrusion. This study aimed to determine differences in maxillofacial morphology between skeletal Class III patients with and without acromegaly using cephalometric analysis. METHODS: Cephalograms of 37 patients with acromegaly (Acro), 37 age-matched non-acromegalic patients with skeletal Class III malocclusion (C-III), and 37 age-matched Class I malocclusion patients (C-I; control) were retrospectively collected. The skeletal and dental morphology of each group was analyzed using cephalometric analysis, which included linear and angular measurements and facial profilograms. In addition, we analyzed diagnostic performance and cutoff values for discriminating acromegaly from skeletal Class III malocclusion using receiver operating characteristic (ROC) curve analysis. RESULTS: The mandibular ramus height was larger in the Acro group than in the other groups. The increase in L1/MP in the Acro group, which represented labial inclination of the mandibular central incisors, was the most characteristic feature in this study. ROC curve analysis indicated that a cutoff value of 88.4° for L1/MP had the highest diagnostic performance in discriminating acromegaly from non-acromegalic Class III malocclusion. CONCLUSIONS: Acromegaly was characterized by a greater degree of bimaxillary prognathism than was non-acromegalic Class III malocclusion. Focusing on labial inclination of the mandibular central incisors would be the most useful way to differentiate acromegaly from non-acromegalic Class III malocclusion.

Dental care using an oral appliance to support hematopoietic stem cell transplantation for NK/T cell lymphoma, nasal type, with palatal perforation.

PATIENT: A 33-year-old man diagnosed with extranodal natural killer cell/T-cell lymphoma, nasal type (ENKTCL-NT) inducing palatal perforation was referred to the perioperative oral care support center of Tohoku University Hospital for dental care to support cancer treatment including chemotherapy and hematopoietic stem cell transplantation (HSCT). Dental review during chemotherapy revealed mucositis suspected to be caused by mucosal trauma from altered jaw function (chewing and speech) due to palatal perforation. Although the patient was already in the cleanroom, an oral appliance as well as conservative care as recommended in oral management guidelines for HSCT were used to prevent worsening of oral mucositis at subsequent HSCT including High-dose chemotherapy and total body irradiation. After HSCT, a prosthodontist fitted a palatal obturator made by a dental technician and an oral surgeon reviewed the necrotic bone and removed the sequestra according to the changes in the palate. This approach involving a multidisciplinary team including a hematologist improved the impaired oral function and minimized oral complications. DISCUSSION: ENKTCL-NT and its treatment have a significant impact on patients' oral status. Hence, it is important to provide customized dental care based on previously endorsed guidelines according to the type of disease, treatment requirements, and oral and systemic status. CONCLUSION: This report indicated the importance of dental care with a customized plan before, during, and after HSCT for ENKTCL-NT with multidisciplinary supportive care for cancer patients to improve the impaired oral function and to minimize oral complications.

The effects of perioperative oral management on perioperative serum albumin levels in patients treated surgically under general anesthesia: A multicenter retrospective analysis in Japan.

ABSTRACT: The purpose of the present study was to investigate the efficacy of perioperative oral managements (POMs) on perioperative nutritional conditions in patients undergoing surgery with general anesthesia. Medical records were retrospectively reviewed and the effects of POMs were investigated based on a large number of cases using a multicenter analysis. The profile of serum albumin levels was assessed and compared between patients with and without POMs using the multivariate analysis. Seventeen Eleven thousand and one hundred sixty patients (4,873 males and 6,287 females) were reviewed. Of these, 2710 patients (24.3%) had undergone POMs. The results of a multivariate analysis revealed the significant positive effect of POMs on perioperative serum albumin level (change between at admission and discharge, (Estimate: 0.022, standard error: 0.012, P < .0001). Patient gender, age, surgical site, performance status, the American Society of Anesthesiologists (ASA) physical status classification, operation time, amount of blood loss, and serum albumin level at admission were also significant predictors. Adjusted multivariate analysis of the effects of POMs on perioperative change of serum albumin level in all subjects reveled the significance of POMs intervention (estimate: 0.022, standard error: 0.012, P < .0001). These results suggest that POMs exerts significant positive effects on perioperative serum albumin levels in patients underwent surgery under general anesthesia.

Comparative Study of Multiple High-Signal-Intensity Spots on 3D and 2D Magnetic Resonance Sialography for Patients with Sjögren's Syndrome.

We investigated the sensitivities of 2-dimensional (2D) magnetic resonance sialography (MR-S) and unilateral sagittal and axial 3-dimensional (3D) MR-S using a surface coil and their combination in diagnosing patients with Sjögren's syndrome (SS). We retrospectively analyzed the 3D and 2D MR-S results of 78 patients with SS. We evaluated the sensitivities of multiple high-signal-intensity spots and staging on MR sialograms and analyzed the efficient imaging methods and cross section for diagnosing patients with SS. The sensitivities of MR-S for detecting abnormal findings (i.e., MR-S stage 1 or higher) were as follows: 65 cases (83.3% [95% confidence interval (CI): 73.2-90.8]) for unilateral sagittal 3D MR-S; 62 cases (79.4% [95% CI: 68.8-87.8]) for axial 3D MR-S; 66 cases (84.6% [95% CI: 74.7-91.8]) for combined unilateral sagittal and axial 3D MR-S; and 32 cases (41.0% [95% CI: 30.0-52.7]) for bilateral sagittal 2D MR-S. The ratio of the abnormal finding of MR-S was tested using the two-tailed Fisher's exact test. Unilateral sagittal, axial, and combined unilateral sagittal and axial 3D MR-S showed significantly higher sensitivity than bilateral sagittal 2D MR-S, respectively (P < 0.001). Most cases upstaged by 3D MR-S were those positive (stage 1 or higher) among the stage 0 cases detected by 2D MR-S. Axial 3D MR-S, compared with 2D MR-S, understaged four cases, which was due to the imaging range of the axial 3D MR-S. We concluded that a single unilateral sagittal 3D MR-S was sufficient and axial 3D MR-S was unnecessary for SS staging. T1- and T2-weighted images are essential for investigating the salivary glands in patients with SS. Therefore, we also concluded that bilateral sagittal 3D MR-S of the parotid glands in addition to T1- and T2-weighted imaging is necessary, sufficient, and most efficient for precise MR imaging examination of the salivary glands, including diagnosing SS.

Florid Cemento-Osseous Dysplasia-Associated Simple Bone Cyst Showing Marked Irregular Border and High Apparent Diffusion Coefficient Value.

A simple bone cyst (SBC) is an intrabone cavity without epithelial lining, which occasionally occur with fibrous-osseous lesions. The imaging finding of the scalloped border and conserving the lamina dura, periodontal ligament spaces, or follicular spaces are considered radiographically pathognomonic of SBC. SBC has been reported to occur with fibrous-osseous lesions, including cemento-osseous dysplasia (COD). Computed tomography (CT) imaging findings are sparse, and there are no reports of magnetic resonance imaging (MRI) findings, including apparent diffusion coefficient (ADC) value calculated by diffusion-weighted MRI for the florid COD-associated SBC. We report a case of a 39-year-old woman who was referred to our hospital because a panoramic radiograph of her right mandible showed asymptomatic radiolucency in the apical molar area. CT images showed a low-density lesion in the periapical areas of the right mandible, which accompanied a well-defined, high-density lesion, and a mixed low/high-density lesion with an unusual marked irregular border in the left mandible. The MRI showed cyst-like extremely hyperintense signals on fat-suppressed T2-weighted images at the right mandibular low-density and the left mandibular mixed low/high-density areas. ADC map showed high values (over 2.5 × 10-3 mm2/s) at the cystic areas in the bilateral mandible. We performed incisional biopsies of the bilateral mandibular lesions and resections of the bilateral maxillary lesions. Surgical and histopathological findings established a diagnosis of florid COD in the bilateral mandible and maxilla, simultaneously complicated by multiple SBCs in the bilateral mandible. The ADC value of cystic component is useful for the diagnosis, if the COD-associated SBC exhibits solitary, nonspecific, or rare imaging findings.

Influence of bone condition on implant placement accuracy with computer-guided surgery.

BACKGROUND: The impact of the jaw bone condition, such as bone quantity and quality in the implant placement site, affecting the accuracy of implant placement with computer-guided surgery (CGS) remains unclear. Therefore, this study aimed to evaluate the influence of bone condition, i.e., bone density, bone width, and cortical bone thickness at the crestal bone on the accuracy of implant placement with CGS. METHODS: A total of 47 tissue-level implants from 25 patients placed in the posterior mandibular area were studied. Implant placement position was planned on the simulation software, Simplant® Pro 16, by superimposing preoperative computed tomography images with stereolithography data of diagnostic wax-up on the dental cast. Implant placement surgery was performed using the surgical guide plate to reflect the planned implant position. The post-surgical dental cast was scanned to determine the position of the placed implant. Linear and vertical deviations between planned and placed implants were calculated. Deviations at both platform and apical of the implant were measured in the bucco-lingual and mesio-distal directions. Intra- and inter-observer variabilities were calculated to ensure measurement reliability. Multiple linear regression analysis was employed to investigate the effect of the bone condition, such as density, width, and cortical bone thickness at the implant site area, on the accuracy of implant placement (α = 0.05). RESULT: Intra- and inter-observer variabilities of these measurements showed excellent agreement (intra class correlation coefficient ± 0.90). Bone condition significantly influenced the accuracy of implant placement using CGS (p < 0.05). Both bone density and width were found to be significant predictors. CONCLUSIONS: Low bone density and/or narrow bucco-lingual width near the alveolar bone crest in the implant placement site might be a risk factor influencing the accuracy of implant placement with CGS.

The effectiveness of an actuator-driven pulsed water jet for the removal of artificial dental calculus: a preliminary study.

BACKGROUND: While hand and ultrasonic scalers are the primary tools used for the removal of dental calculus in periodontal treatment, many studies have shown that they also damage the enamel surface. We have developed a novel actuator-driven pulsed water jet (ADPJ) system, which has the ability to selectively remove materials depending on their stiffness. Considering the different material properties between teeth and dental calculus, it might be possible to develop the ADPJ to remove dental calculus without damage to the tooth's enamel surface using a suitable jet pressure. Therefore, the aim of this study was to assess the effectiveness of the ADPJ in removing dental calculus, and the surface features of the teeth after its use. METHODS: A total of 93 artificial teeth coated with artificial dental calculus were examined in this study. The weights of 90 teeth were measured before and after the use of ADPJ, which had an applied voltage setting of 150, 200, or 240 V. The three remaining teeth were instrumented with a conventional hand scaler, ultrasonic scaler, or ADPJ (set at 240 V). Damage to the artificial tooth surfaces was evaluated using 5% Evans blue dye under an optical microscope. Furthermore, apatite pellets, which are utilized as experimental substitutes for natural teeth, were assessed after the use of ADPJ and both conventional scalers. RESULTS: The ADPJ significantly reduced the amount of artificial calculus, and the removal rate was dependent on the applied voltage. No damage was observed on the surface of the artificial tooth and apatite pellet following the use of ADPJ, in contrast to the conventional scalers. CONCLUSIONS: The results of this study demonstrate the in vitro effectiveness of ADPJ in the removal of dental calculus, without causing damage to tooth surfaces.

High detection sensitivity and reliable morphological correlation of PET with a silicon photomultiplier for primary tongue squamous cell carcinoma.

OBJECTIVE: A positron emission tomography (PET) scanner using a silicon photomultiplier (SiPM PET) in place of a photomultiplier tube significantly improves the spatial and time resolution. It may also improve the evaluation of smaller lesions compared to conventional (non-SiPM) PET scanners. We compared the maximum standardized uptake value (SUVmax), detection sensitivity, and morphological correlation using magnetic resonance imaging (MRI) for primary tongue squamous cell carcinoma between the SiPM PET and non-SiPM PET scanner. METHODS: We retrospectively reviewed the F-18 fluorodeoxyglucose (FDG) PET/CT features of tongue squamous cell carcinomas in consecutive, newly diagnosed, and pathologically verified patients. Twenty-five of 46 patients were scanned using SiPM PET scanner and the remaining 21 patients were scanned with a non-SiPM PET scanner. We compared the SUVmax and visual evaluation of primary tumor detectability, and the correlation between the PET-based and MRI-based tumor size (long axis, thickness, and volume). Differences in SUVmax and detection sensitivity for the primary tumor were analyzed using Welch's t test and Fisher's exact test, respectively. Correlations among the PET-based, MRI-based tumor size, and SUVmax were assessed using Spearman's rank correlation coefficient. RESULTS: SUVmax of both T1/T2 and T3/T4 primary tumors were significantly higher for the SiPM PET (T1/T2 mean SUVmax: 6.6 ± 4.3, T3/T4 mean SUVmax: 18.2 ± 9.8) than that for the non-SiPM PET (T1/T2 mean SUVmax: 3.4 ± 1.4, T3/T4 mean SUVmax: 10.2 ± 4.9) (P < 0.05). While all cases of T3/T4 primary tumors were detected by both PET scanners, the detection sensitivity for T1/T2 primary tumors was significantly higher for the SiPM PET (80%) than that for the non-SiPM PET (36.4%) (P < 0.05). MRI-based tumor size correlated significantly with SiPM PET-based tumor long axis (ρ = 0.74) and volume (ρ = 0.91), but not with the non-SiPM PET-based tumor long axis and volume in T1/T2 primary lesions. Correlation between MRI-based tumor size and SUVmax was significant in both PET scanners; however, no significant difference was observed between the two scanners. CONCLUSIONS: The SiPM PET provides better detection sensitivity and a reliable morphological correlation for the T1/T2 primary tongue tumors than the non-SiPM PET due to its high performance.

Influence of oestrogen deficiency and excessive mechanical stress on condylar head of mandible.

OBJECTIVE: We assessed the aetiology of idiopathic condylar resorption by examining the effects of oestrogen and compressive mechanical stress under a low systemic oestrogen condition in temporomandibular joints (TMJ) caused by an ovariectomy. MATERIALS AND METHODS: Female rabbits were divided into non-ovariectomy (non-OVX) and ovariectomy (OVX) groups. A cortical osteotomy was performed with a custom device that was increased in length by 0.25 mm every 12 hr for 1 week after the operation, during which the TMJs in the rabbits received compressive mechanical stress. Samples from both groups were examined with micro-computed tomography and histological staining. RESULTS: Area and depth of bone resorption were both greater in the OVX group. Furthermore, a significantly earlier and greater prevalence of sub-condylar bone resorption was noted in that group, while cells positive for tartrate-resistant acid phosphatase were increased in the OVX group. CONCLUSIONS: The present findings suggest that oestrogen induced a much greater amount of bone resorption on the anterior surface of the condylar head at an earlier stage in the TMJs of the present model rabbits. Thereafter, restoration of TMJ function appeared to occur in a normal manner.

Effect of exposure parameters and gutta-percha cone size on fracture-like artifacts in endodontically treated teeth on cone-beam computed tomography images.

OBJECTIVES: To ascertain the effects of exposure parameters (tube current and tube voltage) and the gutta-percha cone (GPC) size on root fracture-like artifacts obtained with cone-beam computed tomography (CBCT). METHODS: Fracture-like artifacts appearing on CBCT images of nine extracted human mandibular premolars filled with GPCs of size #50 or #80 were analyzed using six exposure factors: two tube voltages (80 kV and 110 kV); and three tube currents (4 mA, 7 mA, and 10 mA). On axial images, the gray value (GV) was recorded at three points: the mesiobuccal portion (MBP) as the sound dentin, the mesial portion (MP) as the artifact line, and the water area (WA). The rate of decrease in the GV (RDGV) of the artifact line was calculated using the formula: RDGV (%) = (GV of MBP - GV of MP) × 100/(GV of MBP - GV of WA). RESULTS: Comparison of the #80 group and the #50 group with equal tube voltages and tube currents shows that artifact lines in the #80 group were more obvious than those in the #50 group. The artifact lines with 80 kV were markedly more visible than those with 110 kV for each tube current and GPC size. Tube current changes did not affect the artifact line for any tube voltage or GPC size. CONCLUSIONS: For the reduction of artifacts, we recommend selection of higher tube voltages and lower tube currents when taking CBCT images of teeth with each GPC size.