Relationship between image information content and observer performance in digital intraoral radiography.

Objectives: This study conducted a receiver operating characteristic (ROC) analysis by applying improved cluster signal-to-noise (CSN) analysis to digital intraoral radiographs and develop an observer-free method of analyzing image quality related to the observer performance in the detection task.

Methods: Two aluminum step phantoms with a thickness interval of 1.0 mm were used for this study.

A comparison among gamma distribution, intravoxel incoherent motion, and mono-exponential models with turbo spin-echo diffusion-weighted MR imaging in the differential diagnosis of orofacial lesions.

Objectives: To compare the gamma distribution (GD), intravoxel incoherent motion (IVIM), and monoexponential (ME) models in terms of their goodness-of-fit, correlations among the parameters, and the effectiveness in the differential diagnosis of various orofacial lesions.

Methods: A total of 85 patients underwent turbo spin-echo diffusion-weighted imaging with six b-values. The goodness-of-fit of three models was assessed using Akaike Information Criterion.

Gamma distribution model of diffusion MRI for the differentiation of primary central nerve system lymphomas and glioblastomas.

The preoperative imaging-based differentiation of primary central nervous system lymphomas (PCNSLs) and glioblastomas (GBs) is of high importance since the therapeutic strategies differ substantially between these tumors. In this study, we investigate whether the gamma distribution (GD) model is useful in this differentiation of PNCSLs and GBs. Twenty-seven patients with PCNSLs and 57 patients with GBs were imaged with diffusion-weighted imaging using 13 b-values ranging from 0 to 1000 sec/mm2.

The application of a gamma distribution model to diffusion-weighted images of the orofacial region.

Objectives: This study evaluated the correlation among the diffusion-derived parameters obtained by monoexponential (ME), intravoxel incoherent motion (IVIM) and γ distribution (GD) models and compared these parameters among representative orofacial tumours.

Methods: Ninety-two patients who underwent 1.5 T MRI including diffusion-weighted imaging were included.

Prediction of detectability of the mandibular canal by quantitative image quality evaluation using cone beam CT.

Objectives: To compare the results of a new quantitative image quality evaluation method that requires no observers with the results of receiver operating characteristic (ROC) analysis in detecting the mandibular canal (MC) in cone beam CT (CBCT) images.

Methods: A Teflon (polytetrafluoroethylene) plate phantom with holes of different depths was scanned with two CBCT systems. One CBCT system was equipped with an image intensifier (Experiment 1), and the other was equipped with a flat panel detector (Experiment 2).

Effects of exposure parameters and slice thickness on detecting clear and unclear mandibular canals using cone beam CT.

Objectives: The purpose of this study was to clarify the effects of exposure parameters and image-processing methods when using CBCT to detect clear and unclear mandibular canals (MCs).

Methods: 24 dry half mandibles were divided into 2 groups with clear and unclear MCs based on a previous CBCT study. Mandibles were scanned using a CBCT system with varying exposure parameters (tube voltages 60 kV, 70 kV and 90 kV; and tube currents 2 mA, 5 mA, 10 mA and 15 mA) to obtain a total of 144 scans.

A new method to evaluate image quality of CBCT images quantitatively without observers.

Objectives: To develop an observer-free method for quantitatively evaluating the image quality of CBCT images by applying just-noticeable difference (JND).

Methods: We used two test objects: (1) a Teflon (polytetrafluoroethylene) plate phantom attached to a dry human mandible; and (2) a block phantom consisting of a Teflon step phantom and an aluminium step phantom. These phantoms had holes with different depths.

Localization of the primary taste cortex by contrasting passive and attentive conditions.

The primary taste cortex is located in the insula. However, exactly where in the insula the human primary taste cortex is located remains a controversial issue. Human neuroimaging studies have shown prominent variation concerning the location of taste-responsive activation within the insula.

The temporal change in the cortical activations due to salty and sweet tastes in humans: fMRI and time-intensity sensory evaluation.

It remains unclear how the cerebral cortex of humans perceives taste temporally, and whether or not such objective data about the brain show a correlation with the current widely used conventional methods of taste-intensity sensory evaluation. The aim of this study was to investigate the difference in the time-intensity profile between salty and sweet tastes in the human brain. The time-intensity profiles of functional MRI (fMRI) data of the human taste cortex were analyzed using finite impulse response analysis for a direct interpretation in terms of the peristimulus time signal.

Three-dimensional analysis of the temporomandibular joint and fossa-condyle relationship.

Aim: To assess the three-dimensional (3D) position of the temporomandibular joint (TMJ) in the cranial base structure, the 3D morphology of the TMJ, and the fossa-condyle interspaces in subjects with normal occlusion and patients with mandibular asymmetries using 3D computed tomography (CT) images. We hypothesized that the fossa-condyle interspaces and the shape or size of the TMJ would correlate with mandibular asymmetry.

Methods: Twenty women with mandibular asymmetry and nine control subjects were recruited.

Localization of brain activation by umami taste in humans.

There are no credible data to support the notion that individual taste qualities have dedicated pathways leading from the tongue to the end of the pathway in the brain. Moreover, the insular cortex is activated not only by taste but also by non-taste information from oral stimuli. These responses are invariably excitatory, and it is difficult to determine whether they are sensory, motor, or proprioceptive in origin.

[Comparison of a dental cone beam CT with a multi-detector row CT on effective doses and physical image quality].

The purpose of this study was to compare a dental cone beam computed tomography (dental CBCT) and a multi-detector row CT (MDCT) using effective doses and physical image quality. A dental mode (D-mode) and an implant mode (I-mode) were employed for calculating effective doses. Field of view (FOV) size of the MDCT was 150 mm.

Assessment of the sequential change of the masseter muscle by clenching: a quantitative analysis of T1, T2, and the signal intensity of the balanced steady-state free precession.

Background: The persistent muscle contractions during clenching are thought to cause some temporomandibular disorders. However, no report has so far evaluated the effect of clenching on the masticatory muscles by magnetic resonance imaging (MRI).

Purpose: To investigate the effect of clenching with maximum voluntary contraction on the T(1), T(2), and signal intensity (SI) of the balanced fast field-echo (b FFE) of the masseter muscle.

A 3-dimensional method for analyzing the morphology of patients with maxillofacial deformities.

Introduction: Traditionally, cephalograms have been used to evaluate a patient's maxillofacial skeleton and facial soft-tissue morphology. However, magnification and distortion of the cephalograms make detailed morphologic analysis difficult in patients with complex deformities. The purpose of this article was to introduce a new method for visualizing deformation and deviation of the maxillofacial skeleton and facial soft tissues.

A 3-dimensional method for analyzing facial soft-tissue morphology of patients with jaw deformities.

Introduction: Traditional cephalometric radiographs can analyze facial soft-tissues 2 dimensionally. Because they cannot provide information about the nose, lips, cheeks, and mouth, another method is needed to analyze these soft tissues. We introduce a new method for analyzing the 3-dimensional (3D) shape and size of facial soft-tissue morphology.

Four-dimensional analysis of stomatognathic function.

Many researchers have attempted to clarify the complex relationships between stomatognathic function and craniofacial morphology. Most studies investigated the trajectories of incisal or condylar points and measured temporomandibular morphology projected onto 2-dimensional radiographic films. Although these methods provided valuable information, their diagnostic capabilities were limited.

Three-dimensional analysis system for orthognathic surgery patients with jaw deformities.

Introduction: Traditionally, lateral and frontal cephalograms are used with facial photographs to evaluate a patient's maxillofacial skeletal and facial soft-tissue morphology. However, the enlargement and distortion of 2-dimensional radiography made it difficult to accurately conceptualize the patient's anatomy. The purpose of this article was to introduce a new method for comparing 3-dimensional (3D) standard values of the maxillofacial skeletal and facial soft-tissue morphology before and after orthognathic surgery.

The development of a novel automated taste stimulus delivery system for fMRI studies on the human cortical segregation of taste.

fMRI indicated that the primary taste cortex is activated not only by taste but also by non-taste information from oral stimuli. Head movements caused by swallowing are very critical problem in fMRI and inherent difficulties to modulate taste stimuli in the mouth exist to elucidate functional segregation of human brain. We developed a novel automated taste stimulus delivery system for fMRI studies to segregate the pure taste area in the primary taste cortex in humans.

The accuracy of 3-dimensional magnetic resonance 3D vibe images of the mandible: an in vitro comparison of magnetic resonance imaging and computed tomography.

Objective: The purpose of this study was to investigate in vitro the accuracy of three-dimensional (3D) magnetic resonance imaging (MRI) to measure the mandible.

Study Design: The optimal MRI sequence for 3D mandible from the data of 2 volunteers was determined to be 3D vibe. MRI and computed tomography (CT) scans of tube, mandible, and hemimandible phantoms were obtained.

Quantitative analyses of sonographic images of the parotid gland in patients with Sjögren's syndrome.

The first purpose of this study was to quantify the sonographic images of the salivary gland to differentiate the Sjögren syndrome (SS) group from the non-SS group. We included 132 patients in this study who had been referred to our department because of a suspicion of SS. A total of 91 patients fulfilled the criteria for SS, whereas the remaining 41 patients did not.

Sonographic texture characterization of salivary gland tumors by fractal analyses.

The purpose of this study was to quantify the sonographic images of salivary gland tumors. The study population consisted of 21 pleomorphic adenomas, seven Warthin's tumors and 15 malignant tumors. We selected the region-of-interest within the lesion.

Three-dimensional computer-generated head model reconstructed from cephalograms, facial photographs, and dental cast models.

Purpose: Three-dimensional (3D) computer models of the human craniofacial structure have been constructed with computed tomography (CT). However, the high cost of CT and the radiation exposure are drawbacks to this method. Attempts to create a 3D reconstruction from lateral and frontal cephalograms have failed because of problems with magnification, distortion, and limitations of landmark identification, among others.

Change of sonographic findings on cervical lymph nodes before and after preoperative radiotherapy.

The aim of this study was to assess the changes in the power Doppler sonographic findings in patients with oral cancer undergoing chemotherapy and radiotherapy. We performed US examinations on 187 cervical lymph nodes (71 metastatic and 116 reactive nodes) excised from 52 patients before and after preoperative therapy. On Power Doppler images, we calculated the vascular index (VI) and evaluated the vascular pattern.