[Show abstract][Hide abstract] ABSTRACT: We assessed the effect of teeth clenching on handgrip force behaviorally, and investigated cortical activity during the occurrence of facilitatory effects using functional magnetic resonance imaging (fMRI). Twenty-three participants were assessed as to whether they had habitual teeth clenching during maximal voluntary contraction (MVC) exertion, and 21 of them were identified to have such a habit. For those participants, behavioral testing showed that MVC with clenching was greater compared with without clenching (approximately 108% greater on average). Next, cortical activity was measured under gripping with clenching (GwC), gripping without clenching (GwoC), and teeth clenching (C) conditions. We found that the activity of the hand region in primary motor cortex (M1), cingulate motor area/supplementary motor area (CMA/SMA) and anterior cerebellum (AC) was greater in contrast of GwC vs. (GwoC+C). Furthermore, significant correlation was observed between the increasing ratio of the handgrip force and the % signal change in the hand region of M1 and AC, but not in CMA/SMA. These results suggest that the activation in the hand region of M1 and AC may facilitate the spinal motoneurons, and the activation in the hand region in M1 by clenching may be due to a signal from CMA/SMA.
Neuroscience Research 12/2013; · 2.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study evaluates the spatial resolution of cone beam computed tomography for dental use (CBCT) via modulation transfer function (MTF) analyses.
Two models of CBCT system, 3DX FPD8 and FineCube v.12, were used. MTF analysis was applied to each CBCT system using a thin tungsten wire technique.
The MTF curves in the radial direction on the XY-plane were concordant regardless of position, whereas the curves in the azimuthal direction tended to decrease as the distance from the rotation center increased. In the Z-axis direction, the MTF curve of the medial level of the field of view was superior to that of any other level.
The spatial resolution of CBCT systems depends on the location within the field of view. Because the spatial resolution was the highest in the medial level and rotation center position, an object should be placed at this position during a CBCT examination.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to investigate the imaging characteristics of peripheral nerve sheath tumors (PNSTs) in the jaw.
Imaging studies of 6 patients were retrospectively reviewed. Conventional radiography, computed tomography, and magnetic resonance imaging were performed in all patients.
A fusiform lesion continuous with the nerve was observed in 2 cases, with the tumor arising within the inferior alveolar canal. In the other 4 cases, with the tumor arising outside the canal, the tumor had protruded and eroded into the bone. Protrusion was also present in 1 of the 2 cases, with the tumor arising within the canal. A target or fascicular sign was observed each in 1 case.
A fusiform lesion continuous with the nerve and a target or fascicular sign was only present in a few cases. The PNSTs, however, showed a tendency to protrude into the bone.
[Show abstract][Hide abstract] ABSTRACT: PURPOSE: The aim of this study was to compare panoramic and paraxial views of dental CT reformatted images to detect the mandibular canal, and to evaluate the usefulness of the dental CT software function of "Outlining the Mandibular Canal in the Panoramic View". METHODS: One hundred and fifty-five patients (310 sides), who underwent multi-slice computed tomography examination for pretreatment planning of dental implant were analyzed. After scanning, two types of dental CT reformatted image, panoramic and paraxial views were obtained. Two oral radiologists evaluated both views for the visibility of the mandibular canal using a 5-point rating scale: score 5, 100-80 % visible, to score 1, 20-0 % visible. The visibility scores of the two views were evaluated and compared by Wilcoxon's signed rank test. RESULTS: The mean ± standard deviations of panoramic and paraxial views were 4.2 ± 1.1 and 3.5 ± 1.2, respectively, and the former was significantly higher than the latter (p < 0.001). On the basis of these results, we attempted to apply the function of "Outlining the Mandibular Canal in the Panoramic View" to cases with poor visibility of the canal (score 1, 2 or 3) on paraxial views. Consequently, we could reduce the number of such cases from 128 (41 %) to 56 (18 %). CONCLUSIONS: The detectability of the mandibular canal was significantly higher in panoramic views than in paraxial views. Using the function of "Outlining the Mandibular Canal in the Panoramic View", the precision for identifying the canal on paraxial views was considered to be improved.
[Show abstract][Hide abstract] ABSTRACT: To evaluate the visibility of the superior and inferior borders of mandibular canal using panoramic radiography (PR) and cross-sectional computed tomography (CT) images.
Digital panoramic images and cross-sectional CT images of 100 patients were evaluated. The mandibular canal was divided into 4 areas of equal width (1-4), from anterior to posterior. The visibility of the superior and inferior borders was assessed using a 5-point visibility scoring system, with lower scores for worse visibility.
For both modalities, the superior border showed significantly lower score than the inferior border in all areas. For the superior border, areas 1, 2, and 3 all showed significantly lower scores than area 4 for PR, whereas only area 1 showed a lower score than area 4 for CT.
The visibility of the superior border was very poor on panoramic images. The use of cross-sectional CT images remarkably improved this poor visualization.
[Show abstract][Hide abstract] ABSTRACT: Objective
Owing to the complexity of the human language, numerous individuals develop different types of speech disorders. Some patients with cleft lip and/or palate (CLP) exhibit compensatory misarticulations (CMAs), which decrease speech fluency and interfere with the intelligibility of the speaker. The glottal stop (GS) is representative of CMAs in CLP patients. The glottal stop results from an occlusion or lack of airflow at the level of the glottis. In the context of speech therapy for CLP patients, intelligibility is usually used as an outcome measure. However, little is known about the behavioral and neurobiological mechanisms involved in the perception of speech produced by an individual with CMAs. We aimed to investigate the perception of GS compared to normal articulation (NA) using behavioral and neuroimaging experiments.Materials and methodsTwenty healthy subjects without CMAs listened to auditory stimuli (NA and GS) and were asked to distinguish NA from GS using the button-press response during functional magnetic resonance imaging (fMRI).ResultsThe reaction time for the perception of GS was significantly longer than that for NA. Additionally, the activation area and the percentage signal change in the auditory cortex were larger when the subjects listened to GS compared to NA. The auditory association area, which controls the higher-level processing of auditory signals, exhibited more intense bilateral activation in response to GS as compared to NA.Conclusions
In subjects without GS, the perception of GS sounds may require more auditory attention and more complex auditory processing than the perception of NA sounds.
[Show abstract][Hide abstract] ABSTRACT: 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.
Nuclear Medicine Communications 11/2012; · 1.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVES: To investigate characteristic MRI findings of rheumatoid arthritis (RA) in the temporomandibular joints (TMJs). METHODS: 61 patients (122 TMJs) with RA in the TMJ and 50 patients (100 TMJs) with temporomandibular disorder (TMD) were included in this study. MR images of these patients were assessed by two oral radiologists for the presence or absence of osseous changes, disc displacement, joint effusion and synovial proliferation. These findings were compared between the two patient groups. RESULTS: Osseous changes in the condyle and articular eminence/fossa in the RA patient group were significantly more frequent than in the TMD patient group, and were often very severe. Joint effusion was also significantly more frequent in the RA patient group. Synovial proliferation was found in all TMJs in the RA patient group, whereas it was very uncommon in the TMD patient group. CONCLUSIONS: Severe osseous changes in the condyle and synovial proliferation were considered characteristic MRI findings of RA in the TMJs.
[Show abstract][Hide abstract] ABSTRACT: 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).
Six patients with histopathologically confirmed TMJ cysts who were examined by MRI were included in this study. Two oral radiologists retrospectively evaluated MR images.
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.
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.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to investigate the imaging findings of non-Hodgkin lymphoma (NHL) involving the mandible.
The imaging studies of 4 patients with NHL involving the mandible were retrospectively reviewed. Panoramic and computerized tomographic (CT) images were available for all patients. Magnetic resonance imaging (MRI) was available for 3 patients.
On panoramic images, an apparent radiolucent lesion was found in only 2 of 4 cases. However, in all cases careful observation demonstrated imaging findings suggesting malignancy. On CT and MRI, tumor replaced the bone marrow in all cases and spread to the surrounding soft tissue in 3 cases. Cortical bone destruction tended to be mild for the extent of tumor involvement.
NHL involving the mandible tended to show slight or mild cortical bone destruction relative to the extent of the tumor involvement. Careful observation was considered to be necessary when interpreting conventional images, because they might not clearly demonstrate bone destruction.
[Show abstract][Hide abstract] ABSTRACT: To investigate the clinical and radiological characteristics of odontogenic carcinomas (OCs) and evaluate their impact on early clinical diagnosis.
The clinical and radiological features of all patients with OCs in our pathology record from January 1988 to December 2009 were retrospectively reviewed. The impact on a tentative diagnosis before final histological examination of clinical, panoramic and CT features was investigated.
Of 474 cases with malignant jaw tumours, 417 (88%) were gingival squamous cell carcinomas (SCCs) and 27 (6%) were OCs. The average age of the patients with OCs was significantly lower than that of those with gingival SCCs. 20 OCs were in the mandible and 7 were in the maxilla. 22 OC patients (81%) had pain and/or swelling as an initial symptom of the disease. Although the majority of OCs showed irregularly contoured radiolucency, one-third of the cases showed cyst-like radiolucency totally or partially surrounded by a sclerotic rim on panoramic radiography. Permeative or gross cortical bone destruction and mass extension outside the jaw bone were found on CT and a diagnosis of malignant tumour was more common. Mass extension outside the cortex had a significant influence on malignant diagnosis. However, 22% of the patients were still clinically diagnosed as having osteomyelitis after CT.
Although CT was useful to obtain a diagnosis of malignant tumour in OC patients, 22% of patients were clinically diagnosed as having osteomyelitis even after CT. When an osteomyelitis case is resistant to conventional therapy and gross bone destruction and/or mass extension is found on CT, a histopathological examination should be done.
[Show abstract][Hide abstract] ABSTRACT: Active targeting by monoclonal antibodies (mAbs) combined with nanosize superparamagnetic iron oxide (SPIO) is a promising technology for magnetic resonance imaging (MRI) diagnosis. However, the clinical applicability of this technology has not been investigated using appropriate controls. It is important to evaluate the targeting technology using widely used clinical 1.5-Tesla MRI in addition to the high-Tesla experimental MRI. In this study, we measured mAb-conjugated dextran-coated SPIO nanoparticles (CMDM) in vivo using clinical 1.5-Tesla MRI. MRI of tumor-bearing mice was performed using a simple comparison between positive and negative tumors derived from the same genetic background in each mouse. The system provided significant tumor-targeting specificity of the target tumor. To the best of our knowledge, this is the first report on the specific detection of target tumors by mAb-conjugated SPIO using clinical 1.5-Tesla MRI. Our observations provide clues for reliable active targeting using mAb-conjugated SPIO in clinical applications.
Journal of Controlled Release 01/2012; 159(3):413-8. · 7.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To evaluate the spatio-temporal relationships between articulators in the anterior oral cavity, during the production of Japanese fricative and plosive articulation using our proposed method for tooth visualization in MR image sequences.
Ten healthy adults without malocclusion participated in the study. Customized maxillary and mandibular plates with space around the central incisors that was to be filled with MR-compatible contrast medium were made. During image-acquisition by a cine magnetic resonance imaging (MRI) technique, the subjects repeated vowel-consonant-vowel syllables (/asa/ and /ata/) without wearing the plates. The subjects then wore the plates for tooth imaging. All data were acquired in the midsagittal plane. Tooth boundaries were superimposed using landmarks. Several parameters and spatio-temporal changes in the centre of gravity (CoG) of the tongue were measured.
During /t/, the duration and amount of tongue-to-palate/incisor contact were significantly greater and the radius of the inscribed circle between the tongue-maxillary incisor-mandibular incisor was significantly shorter than those during /s/. /t/ also had a more anteriorly located CoG of the tongue than /s/ during maximum constriction. The spatio-temporal changes in the CoG of the tongue were significantly different between /asa/ and /ata/.
We conclude that increased tongue-to-palate/incisor contact and greater anterior closure are necessary for the production of Japanese /t/ compared to /s/. With the use of this new method for tooth visualization in MR image sequences, it should be possible to evaluate the interaction of teeth and other articulators during speech.
Archives of oral biology 12/2011; 57(6):749-59. · 1.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to investigate the signal intensity characteristics of highly invasive and highly metastasizing transplanted human squamous cell carcinoma using ultra-small super-paramagnetic iron oxide (USPIO)-enhanced MRI and to correlate them with USPIO distribution to tumour components revealed by histological examination.
13 nude mice with transplanted human squamous cell carcinoma in the oral cavity were imaged before and 24 hours after intravenous administration of USPIO. The difference in signal intensity between pre-contrast and post-contrast MR images was visually evaluated. For quantitative analysis, signal intensity within a region of interest was measured. Histological findings were correlated with MR findings. The approximate USPIO concentration was evaluated using USPIO phantoms.
Seven tumours had an area showing signal intensity increase on post-contrast T₁ weighted images. Histopathologically, six of those tumours contained a small amount of iron particles in the stroma. The USPIO concentration was presumed low. Two tumours had an area showing signal intensity decrease on post-contrast T₁ and T₂ weighted images. The areas had a large amount of iron particles in the stroma and the USPIO concentration was presumed high. There was a minimal amount of iron particles in tumour parenchymal cells.
The amount of USPIO accumulation into tumour stroma was considered to affect MR signal intensity. A small amount increases T₁ weighted signal intensity, whereas a large amount decreases T₁ and T₂ weighted intensity. The USPIO accumulation into the tumour parenchyma was not thought to affect MR signal intensity.
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: To use an accurate method of tooth visualization in magnetic resonance imaging (MRI) movie for the observation of spatio-temporal relationships among articulators.
The subjects were two volunteers. Each subject repeated a vowel-consonant-vowel syllable (ie, /asa/; /ata/), and the run was measured using a gradient echo sequence. A custom-made clear retainer filled with the jelly form of ferric ammonium citrate was then fit onto the dental arch, and a T1-weighted turbo-spin-echo sequence was taken. Landmarks were used for superimposition of the incisor boundary onto sequential images of MRI movie. Tracings were conducted to observe the spatio-temporal relationships among articulators.
The incisor boundary was clearly visible in the magnetic resonance images. After superimposition, the contact distance of the tongue to palate/incisor was found to be longer during /t/-articulation than during /s/-articulation. There were prominent differences in images with and without tooth superimposition in the front oral cavity.
The method could distinctly extract a tooth boundary in MRI. Detailed configurational relationships between the tongue and tooth were observed during the production of a fricative and a plosive in MRI movie using this method.
The Angle Orthodontist 03/2011; 81(2):237-44. · 1.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: the aim of the study was to evaluate the usefulness of cone beam CT (CBCT) in temporomandibular joints (TMJs) with soft tissue pathology.
106 TMJs of 55 patients with temporomandibular disorder (TMD) were examined by MRI and CBCT. MR images were used for the evaluation of disc displacement, disc deformity, joint effusion and obscurity of temporal posterior attachment (TPA). CBCT images were evaluated for the presence or absence of osseous abnormalities. The chi(2) test was used to analyse the association between MRI and CBCT findings.
MRI of 106 TMJs revealed disc displacement, disc deformity, joint effusion and obscurity of the TPA in 68, 73, 28 and 27 joints, respectively. Of the 68 TMJs with disc displacement, anterior disc displacement without reduction (ADDWR) was seen most frequently (47/68). CBCT imaging found 65 TMJs were characterized by the presence of osseous abnormalities and were significantly associated with disc deformity and ADDWR (P < 0.05). There was no statistically significant association between the presence of joint effusion and obscurity of TPA and TMJ osseous abnormalities.
TMD patients with confirmed ADDWR or disc deformity on MRI are at risk of having osseous abnormalities in the TMJ and further examination with CBCT is recommended.
[Show abstract][Hide abstract] ABSTRACT: With cone beam CT (CBCT) as the reference standard, the objective of this study was to determine the diagnostic accuracy of MRI for assessing osseous abnormalities of the temporomandibular joint (TMJ).
106 TMJs from 55 patients with temporomandibular disorder were examined by CBCT and MRI. CBCT images were evaluated by two experienced oral radiologists with regard to the presence or absence of each of the following eight types of osseous abnormalities: Type 1, destructive and erosive osseous changes of the condyle; Type 2, flattening of the articular surface of the condyle; Type 3, deformity of the condyle; Type 4, sclerosis of the condyle; Type 5, osteophyte formation; Type 6, ankylosis; Type 7, erosion of the articular fossa and/or eminence; and Type 8, sclerosis of the articular fossa and/or eminence. For detection of these osseous abnormalities by MRI, proton density-weighted images and T(2) weighted images were evaluated independently by three observers. Using CBCT findings as the reference standard, the diagnostic performance of MRI for detecting various types of osseous abnormalities was evaluated by calculating its sensitivity and specificity.
Out of 106 joints, CBCT revealed Types 1, 2, 3, 4, 5, 6, 7 and 8 abnormalities in 25, 19, 26, 20, 14, 5, 19 and 22 joints, respectively. The mean sensitivities of MRI among the three observers for detecting Types 1, 2, 3, 4, 5, 6, 7 and 8 abnormalities were 61%, 30%, 82%, 40%, 48%, 34%, 61% and 41%, respectively, whereas the mean specificities were 86%, 92%, 91%, 95%, 84%, 98%, 89% and 91%, respectively.
Although high specificity (84-98%) was obtained with MRI, this modality showed relatively low sensitivity (30-82%) for detecting osseous abnormalities of the TMJ. The value of MRI for the detection of TMJ osseous abnormalities is considered to be limited.
[Show abstract][Hide abstract] ABSTRACT: For surgical procedures involving the posterior mandible, it is important to be familiar with the details of the bifid mandibular canal. To our knowledge, there have been no systematic studies evaluating the bifid mandibular canal using sectional imaging. The purpose of this study is to evaluate the incidence and configuration of the bifid mandibular canal using cone beam CT.
252 patients (301 mandible sides) underwent cone beam CT between October 2004 and September 2005 and were included in this study. The cone beam CT images were evaluated for the presence and configuration of the bifid mandibular canal. The patterns of bifurcation were classified into four types according to the classification of Nortjé et al (Variations in the normal anatomy of the inferior dental (mandibular) canal: a retrospective study of panoramic radiographs from 3612 routine dental patients. Br J Oral Surg 1977; 15: 55-63). The diameter of the accessory canal was classified into two categories: 50% or more and less than 50% of the diameter of the main mandibular canal.
Of the 301 subjects, 47 (15.6%) demonstrated a bifid mandibular canal. They were Type I in 2, Type II in 40, Type III in 0, and Type IV in 5 cases. The diameter of the accessory canal was greater than or equal to 50% of the main canal in 23, and less than 50% in 24 cases.
On the basis of the cone beam CT, a bifid mandibular canal was found in 15.6% of cases, a markedly higher proportion than found in previous reports using panoramic images. Cone beam CT is considered a suitable modality for detailed evaluation of bifid mandibular canals.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to investigate whether it was possible to evaluate bone mineral density (BMD) using voxel values from cone-beam CT (CBCT) for dental use.
A water phantom with an aluminum rod and sample tubes containing iodine solutions of various concentration was imaged by CBCT and multi-slice CT (MSCT). Voxel values and CT numbers, respectively, of the samples were measured and their correlation was investigated. In addition, based on the CT numbers of a hydroxyapatite (HA) reference phantom, a conversion formula from voxel value to BMD was obtained.
There was a positive correlation between the voxel values of CBCT and the iodine concentration of the solutions, regardless of the X-ray dose or the mean energy, although the voxel values had a slight tendency to be saturated at higher iodine concentrations. An excellent correlation between the voxel values and CT numbers was also observed. A regression analysis showed that nonlinear (linear-quadratic model) regression was more appropriate than linear regression fitting for plotting these two values, although the latter might be usable for clinical applications. The conversion formula from the voxel value of CBCT to the equivalent BMD was as follows: y=-0.03669x(2)+3.602x-350.3 (x: voxel value, y: BMD mg/cm(3) HA).
This study revealed that there was a high correlation between the voxel values of CBCT and the CT numbers of MSCT. Although this was an in vitro study with assumed ideal conditions for measuring voxel values, there was a clear possibility for estimating CT numbers and BMD using the voxel values from the CBCT images, but the relationship was not entirely linear and should be examined further.
Clinical Oral Implants Research 05/2010; 21(5):558-62. · 3.43 Impact Factor