Contribution of the complex comprising the masticatory fascia, disc, and capsule to temporomandibular joint stabilization: An anatomical study.

BACKGROUND: Anterior displacement of the temporomandibular joint (TMJ) disc is the most typical pathological condition of TMJ disorders. Structures attached to the articular disc may support the disc in various directions and contribute to stabilizing the TMJ. However, the relationship between the articular disc, capsule, and masticatory muscles remains unclear. Therefore, this study aimed to clarify the relationship between the masticatory muscles, related masticatory fascia, articular disc, and capsule. METHODS: We examined 10 halves from adult Japanese cadavers, with five halves macroscopically analyzed and the remaining five histologically analyzed. The TMJ was dissected from the lateral aspect for gross anatomical analysis. For histological analysis, the relationship between the temporal and masseteric fasciae and the articular capsule was observed in the coronal section. Additionally, we evaluated relationships among the disc, capsule, temporal fascia, and masseteric fascia in 10 living and healthy volunteers using magnetic resonance imaging. RESULTS: The articular disc was attached to the capsule without a clear border. The capsule continued into the masseteric and temporal fasciae. Consequently, the articular disc, capsule, masseteric, and temporal fasciae were considered a single complex. CONCLUSIONS: The single complex of the temporalis, masseter, capsule, masticatory fascia, and disc may antagonize the force in the posterolateral direction through the fascia.

Knowledge and risk perception of radiation for Japanese nursing students after the Fukushima Nuclear Power Plant disaster.

BACKGROUND: The Japanese have had three experiences of radiation disasters: the atomic bombs dropped on Hiroshima and Nagasaki in 1945, and the 2011 Fukushima Nuclear Power Plant disaster. The former two experiences have been covered in compulsory education programs. In light of these incidents, a strong fear of radiation has pervaded people of several generations. In such a situation, the role of nurses is important. When nurses treat residents, their attitudes change depending on how they understand and feel about radiation. The foundations of these attitudes are formed through student education. Hence, it is necessary to explore nursing students' understanding and risk perception of radiation, and the nature of radiation education received. OBJECTIVES: To assess the levels of understanding and risk perception of nursing students regarding radiation. DESIGN: Cross-sectional survey. METHODS: A questionnaire survey was administered to all students (74 first-year, 79 second-year, 65 third-year, and 69 fourth-year students) in the nursing department of a Japanese national university. The response rate was 84%. Respondents were asked to rate their level of understanding of 50 phrases chosen from two supplementary texts about radiation for elementary school students and for middle and high school students, prepared by the Japanese Ministry. Further, they were asked to rate their risk perception for 30 events, and to answer six questions about radiation. RESULTS: It was found that knowledge about radiation among Japanese nursing students was poor, because sufficient radiation education had not been provided. Hence, they displayed a greater fear of X-rays as compared to American students and members of the League of Woman Voters. However, it was also found that an increase in understanding might decrease risk perception. CONCLUSIONS: It was concluded that nursing students require adequate education about radiation, in order to reduce their fear of X-rays and to mitigate their risk perception.

Comparison of radiation risk perception and knowledge of radiation between Indonesian and Japanese dental students.

The purpose of the study was to obtain basic data to identify problems in radiation education in a situation where confidence in nuclear power has fluctuated over time and fear of nuclear power has increased globally due to nuclear power plant disasters at Chernobyl and Fukushima. We conducted a questionnaire survey on understanding and risk perception of radiation and atomic power, before and after lectures, for 107 Japanese and 137 Indonesian dental students. Thirty-six phrases were extracted from two supplementary texts about radiation created by the Japanese Ministry of Education, Culture, Sports, Science and Technology, and 30 events commonly used in research on risk perception were used. The students were asked to rate their level of understanding of 36 phrases and risk perception of 30 events. Moreover, the students were asked to answer 6 general questions about radiation. For Japanese students, understanding of radiation increased and risk perception for both nuclear power and X-rays decreased after lectures (p < 0.05). Concerning nuclear power, the risk-value declined as the level of understanding increased (p < 0.01). However, for Indonesian students, who had lectures on only radiation excluding nuclear power in dental radiology, risk perception increased for X-ray after lectures (p < 0.05). This indicates that thought and custom, in the absence of knowledge, are influenced by lectures. In general, it is said that increase in knowledge will lower risk perception, but even if radiation education is imparted, risk perception may rise if the lectures are not understood properly. It was concluded that educators need to incorporate sufficient knowledge in their teachings, and correct thinking, to mitigate the risk of future radiation education giving the opposite of the intended effect.

Principles of the magnetic resonance imaging movie method for articulatory movement.

Magnetic resonance imaging (MRI) has become a critical tool for dental examination. MRI has many advantages over radiographic examination methods, including the lack of a requirement for patient exposure and the ability to capture high-contrast images of various tissue and organ types. However, MRI also has several limitations, including long examination times and the existence of metallic or motion artifacts. A cardiac imaging method using cine sequences was developed in the 1990s. This technique allows for analysis of heart movement and functional blood flow. Moreover, this method has been applied in dentistry. Recent research involving 3 T MRI has led to the achievement of a temporal resolution of < 10 ms, surpassing the frame rate of typical video recording. The current review introduces the history and principles of the cine sequence method and its application to the oral and maxillofacial regions.

New application of dynamic magnetic resonance imaging for the assessment of deglutitive tongue movement.

BACKGROUND: Deglutitive motion of the tongue may function to maintain tooth position. However, the causation between abnormal patterns of orofacial muscle function and dental malocclusion remains unclear. To clarify the pathogenic mechanism of malocclusion, it is important to determine the relative positional relationship between the tongue tip and incisor edge or the dorsal tongue and palate during deglutition. Here, we assessed the utility of 3-T segmented cine-magnetic resonance (MR) imaging, combined with static MR images for hard tissue visualization, in assessing the relationship between the tongue and the surrounding tissues during deglutitive tongue movement. METHODS: Cine-MR images were acquired from three healthy female volunteers during deglutition who had no history of swallowing disorder or other chronic illness, normal alignment and occlusion, and a skeletal class I relationship. Three cine-MR images were taken during deglutition in accordance with an auditory cue for each volunteer. During static imaging, custom-made, contrast-medium-filled clear retainers were positioned in the mouth to allow visualization of the upper and lower incisors and hard palate boundaries. Static images were superimposed onto images of the three stages in deglutitive tongue movement, which were selected from a series of cine-MR images. These superimpositions were assessed five times by tracing cephalometric parameters to examine the reproducibility of the method. RESULTS: Traces varied little across repeated measurements, and all subjects had a similar pattern of dorsal tongue movement. Tongue-to-palate contact increased slightly during the first to second stage of swallowing and abruptly increased during the second to third stage, while the tongue tip position remained constant. CONCLUSIONS: Segmented cine-MR imaging combined with static MR images is useful for assessing soft tissue motion during deglutition. This method is particularly useful in dentistry to evaluate the relationship between tongue function and maxillofacial morphology in terms of orthodontic treatment and orofacial myofunctional therapy, and for improving tongue movement during speech therapy.

Influence of orthodontic appliance-derived artifacts on 3-T MRI movies.

BACKGROUND: Magnetic resonance imaging (MRI) has been used to study configurations of speech organs in the resting state. However, MRI is sensitive to metals, and numerous types of metallic appliances, most of which have a large magnetic susceptibility, are used in orthodontic treatment and may cause severe artifacts on MRI. We have developed techniques for obtaining MRI movies of the oral region, to evaluate articulatory changes, especially movement of the tongue, palate, and teeth, pre- and post-orthodontic/orthognathic treatment. We evaluated the influence of artifacts caused by orthodontic appliances, including fixed retainers, metal brackets, and wires, on measurements in 3-T MRI movies. METHODS: Sixteen healthy young adults (nine males, seven females; average age, 27 years) with normal occlusion were recruited. Four types of customized maxillary and mandibular plates were prepared by incorporating one of the following into the plate: (a) nothing, (b) a fixed canine-to-canine retainer, (c) metal brackets for the anterior and molar teeth, or (d) clear brackets for the anterior teeth and metal brackets for molars. A 3-T MRI movie, in segmented cine mode, was generated for each plate condition while participants pronounced a vowel-consonant-vowel syllable (/asa/). The size of the artifact due to the metallic brackets was measured. The face size and orthodontically important anatomical structures, such as the velum, the hard palate, and the laryngeal ventricle, were also measured. RESULTS: A large artifact was observed over the entire oral region around orthodontic appliances, altering regional visibility. The velopharyngeal height was measured as significantly longer in the presence of metal brackets. The maximum artifact size due to a metallic bracket was > 8 cm. Our results show that even if it is possible to obtain the measurements of palate length, nasion to sella, and nasion to basion in individuals wearing metal brackets for molars, the measurements might be affected due to the presence of artifacts. CONCLUSIONS: Orthodontic appliances, including metallic materials, sometimes produce significant measurement error in speech evaluation using MRI movies, which often become invisible or distorted by metallic orthodontic appliances. When the distorted image is measured, caution should be exercised, as the measurement may be affected. Based on the study, it is concluded that orthodontists should not necessarily remove all metallic appliances before MRI examination because the influence varies among the appliances and should also know that a significant measurement error in speech evaluation using MRI movie may occur by image distortion caused by metallic artifacts.

Dental students' levels of understanding normal panoramic anatomy.

BACKGROUND/PURPOSE: In dentistry, panoramic radiography is an important examination technique. The Faculty of Dentistry at Tokushima University educates students about panoramic radiographic anatomical landmarks. The purpose of this study was to investigate differences in the understanding of each panoramic anatomical landmark among students. MATERIALS AND METHODS: This study analyzed the results of 40 fifth- and 79 sixth-year faculty students who had taken a written examination to clarify their knowledge of anatomical landmarks in 28 panoramic radiographic regions. Anatomical landmarks were classified into 3 categories: , , and  to compare correct answer rates. RESULTS: The mean overall correct answer rate by the 119 students for the 28 regions was 53%. The rate did not vary between the 2 academic years. On comparison of the 3 categories, significant differences were only observed between  and , as the values for the latter were lower. Among the anatomical landmarks, the rates for the condylar head, hyoid bone, panoramic innominate line, styloid process, and nasopalatine line were higher, and those for ghost images of the contralateral nasopalatine line, the cervical vertebrae, mandibular foramen, mastoid air cell, and posterior pharyngeal wall were lower. The values for , such as the dorsum of tongue, middle and inferior nasal conche, and middle and inferior nasal meatuses, were also lower. CONCLUSION: These results indicate the necessity of improving educational approaches for regions with lower rates of correct answers.

Numerical Evaluation of Image Contrast for Thicker and Thinner Objects among Current Intraoral Digital Imaging Systems.

The purpose is to evaluate the performance of current intraoral digital detectors in detail using a precise phantom and new method. Two aluminum step wedges in 0.5 mm steps were exposed by two photostimulable phosphor plate (PSP) systems-one with automatic exposure compensation (AEC) and the other without AEC-and a CCD sensor. Images were obtained with 3 doses at 60 kV. The effect of metallic material also was evaluated. The contrast-to-noise ratio (CNR) for thinner steps and the low contrast value (LCV) for thicker steps were obtained. The CCD system was the best under all conditions (P < 0.001), although the Gray value was sensitive to the dose, and the Gray value-dose relation varied greatly. The PSP system with AEC was superior to that without AEC for the LCV (P < 0.001) but was inferior to it regarding the CNR (P < 0.001). CNR and LCV in the PSP system without AEC were not affected by the metallic plate. Intraoral digital imaging systems should be chosen according to their diagnostic purpose. PSP system with AEC may be the best for detecting molar proximal caries, whereas the PSP system without AEC may be better for evaluating small bone regeneration in periodontal disease. The CCD system provided the best performance.

Characterization of Swallowing Sound: Preliminary Investigation of Normal Subjects.

OBJECTIVE: The purpose of this study was to characterize the swallowing sound and identify the process of sound generation during swallowing in young healthy adults. METHODS: Thirty-three healthy volunteers were enrolled and allocated into three experimental groups. In experiment 1, a microphone was attached to one of eight cervical sites in 20 subjects, participants swallowed 5 ml water, and the sound waveform was recorded. In experiment 2, 10 subjects swallowed either 0, 5, 10, or 15 ml water during audio recording. In addition, participants consumed the 5 ml bolus in two different cervical postures. In experiment 3, the sound waveform and videofluoroscopy were simultaneously recorded while the three participants consumed 5 ml iopamidol solution. The duration and peak intensity ratio of the waveform were analyzed in all experimental groups. RESULTS: The acoustic analysis of the waveforms and videofluoroscopy suggested that the swallowing sound could be divided into three periods, each associated with a stage of the swallowing movement: the oral phase comprising posterior tongue and hyoid bone movement; the pharyngeal phase comprising larynx movement, hyoid bone elevation, epiglottis closure, and passage of the bolus through the esophagus orifice; and the repositioning phase comprising the return of the hyoid bone and larynx to their resting positions, and reopening of the epiglottis. CONCLUSION: Acoustic analysis of swallowing sounds and videofluoroscopy suggests that the swallowing sound could be divided into three periods associated with each process of the swallowing movement: the oral phase comprising the posterior movement of the tongue and hyoid bone; the pharyngeal phase comprising the laryngeal movement, hyoid bone elevation, epiglottis closure, and the bolus passage to the esophagus orifice; and the repositioning phase comprising the repositioning of the hyoid bone and larynx, and reopening of the epiglottis.

Availability of Japanese Government's supplemental texts on radiation reflecting the Fukushima Daiichi Nuclear Power Plant accident for elementary and secondary education from dental students' understanding.

Following the Fukushima Nuclear Power Plant accident, the Japanese government created two supplemental texts about radiation reflecting the accident for elementary, middle school, and high school students. These texts were made to explain radiation and consequently to obtain public consent for the continuation of the nuclear program. The present study aimed to evaluate the appropriateness of the content of the texts and to collect the basic data on the level of understanding necessary to improve radiation education. Lectures on radiology including nuclear energy and the Fukushima accident were given to 44 fourth-year dental students in 2013. The questionnaire was administered in 2014 when these students were in their sixth-year. The survey was also administered to 40 first-year students and 41 fourth-year students who hadn't any radiology lectures. Students rated their level of understanding of 50 phrases used in the texts on a four-point scale (understanding = 3, a little knowledge = 2, having heard = 1, no knowledge = 0). Questions on taking an advanced physics course in high school and means of learning about radiation in daily life were also asked. The level of understanding of phrases in the supplemental text for middle and high school students was significantly higher among sixth-year students (mean = 1.43) than among first-year (mean = 1.12) or fourth-year (mean = 0.93) students (p < 0.05). Overall, the level of understanding was low, with scores indicating that most students knew only a little. First-year students learning about radiation from television but four-year and six-year students learning about radiation from newspaper scored significantly higher (p < 0.05). It was concluded that radiation education should be improved by using visual material and preparing educators to teach the material for improving the public's understanding of radiation use-especially nuclear power generation because the phrases used in the supplementary texts are very difficult for students to understand.

Infiltration of trace metal ions in the oral mucosa of a rat analyzed using SRXRF, XAFS, and ICP-MS.

Although the accumulation and distribution of metals from metallic orthodontic appliances in the oral mucosa have been studied extensively, they remain unclear because their concentration is quite low. In this study, metal specimens (Ni, Ni-Ti, and Co-Cr) were sutured in the unilateral oral mucosa of rats, and the distribution of the eluted elements in the mucosal tissue was estimated using inductively coupled plasma mass spectrometry (ICP-MS) and synchrotron radiation X-ray fluorescence analysis (SR-XRF). While the infiltrations of Ni, Co, and Cr into the oral mucosal connective tissue were observed with SR-XRF, significant increases were only found in Ni from the pure Ni group and Cr from the Co-Cr group. Furthermore, Ni and Co were estimated as hydrated ions while Cr was estimated in oxide form through X-ray absorption fine structure (XAFS) analysis.

Differences in Velopharyngeal Structure during Speech among Asians Revealed by 3-Tesla Magnetic Resonance Imaging Movie Mode.

OBJECTIVE: Different bony structures can affect the function of the velopharyngeal muscles. Asian populations differ morphologically, including the morphologies of their bony structures. The purpose of this study was to compare the velopharyngeal structures during speech in two Asian populations: Japanese and Thai. METHODS: Ten healthy Japanese and Thai females (five each) were evaluated with a 3-Tesla (3 T) magnetic resonance imaging (MRI) scanner while they produced vowel-consonant-vowel syllable (/asa/). A gradient-echo sequence, fast low-angle shot with segmented cine and parallel imaging technique was used to obtain sagittal images of the velopharyngeal structures. RESULTS: MRI was carried out in real time during speech production, allowing investigations of the time-to-time changes in the velopharyngeal structures. Thai subjects had a significantly longer hard palate and produced shorter consonant than Japanese subjects. The velum of the Thai participants showed significant thickening during consonant production and their retroglossal space was significantly wider at rest, whereas the dimensional change during task performance was similar in the two populations. CONCLUSIONS: The 3 T MRI movie method can be used to investigate velopharyngeal function and diagnose velopharyngeal insufficiency. The racial differences may include differences in skeletal patterns and soft-tissue morphology that result in functional differences for the affected structures.

Use of an advanced 3-T MRI movie to investigate articulation.

OBJECTIVE: To develop a magnetic resonance imaging (MRI) movie to reveal the dynamic movement of articulators and teeth. STUDY DESIGN: Five healthy females with normal occlusion participated in this study. Various concentrations of MRI contrast media (ferric ammonium citrate [FAC]) were tested for visualization of teeth, according to facial markers and with the use of a gel. Custom-made circuitry was connected to synchronize pronunciation of fricative sounds (/asa/) with scans. Three gradient echo sequences (True fast imaging with steady state precession [true FISP], FISP, and fast low angle shot [FLASH]) with a segmented cine were tested with the use of repetition times (TRs) of 9 ms and 31.5 ms. The MRI movie images were superimposed over the boundaries of teeth. The images produced during pronunciation, using the two different TRs (9 ms and 31 ms), were compared to assess the position of the lips and the tongue. RESULTS: Images obtained using the FLASH sequence, with a TR of 9 ms or 31.5 ms, can be used for diagnostic purposes. A TR of 9 ms, with 161 continuous images acquired, produced the highest-quality images of teeth, with few artifacts present. Pronunciation of the consonant "s" was clearly discernable. CONCLUSIONS: Our 3-T MRI movie system, with a temporal resolution less than 9 ms, can provide detailed information pertaining to variations in speech or oropharyngeal function.

Effects of cortical activations on enhancement of handgrip force during teeth clenching: an fMRI study.

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.

Location dependency of the spatial resolution of cone beam computed tomography for dental use.

OBJECTIVE: This study evaluates the spatial resolution of cone beam computed tomography for dental use (CBCT) via modulation transfer function (MTF) analyses. STUDY DESIGN: 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. RESULTS: 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. CONCLUSION: 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.

Magnetic susceptibility and hardness of Au-xPt-yNb alloys for biomedical applications.

Metal devices in the human body induce serious metal artifacts in magnetic resonance imaging (MRI). Metals artifacts are mainly caused by a volume magnetic susceptibility (χv) mismatch between a metal device and human tissue. In this research, Au-xPt-yNb alloys were developed for fabricating MRI artifact-free biomedical metal devices. The magnetic properties, hardness and phase constitutions of these alloys were investigated. The Au-xPt-8Nb alloys showed satisfactory χv values. Heat treatments did not clearly change the χv values for Au-xPt-8Nb alloys. The Vickers hardness (HV) of these two alloys was much higher than that of high-Pt alloys; moreover, aging at 700°C increased the HV values of these two alloys. A dual phase structure consisting of face-centered cubic α1 and α2 phases was observed and aging at 700°C promoted phase separation. The Au-5Pt-8Nb and Au-10Pt-8Nb alloys showed satisfactory χv values and high hardness and are thus suggested as candidates for MRI artifact-free alloys for biomedical applications.

Localizing the mandibular canal on dental CT reformatted images: usefulness of panoramic views.

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.

Stability of voxel values from cone-beam computed tomography for dental use in evaluating bone mineral content.

OBJECTIVES: The objective of this study was to investigate the stability of voxel values from cone-beam CT (CBCT) using a flat panel detector in changing surrounding circumstances mimicking clinical situations. MATERIALS AND METHODS: Seven hydroxyapatite (HA) rods (0, 40, 80, 120, 160, 199, and 239 mg Ca/cm(3) ) were set in a 16 cm diameter water phantom and scanned with CBCT (FineCube) and also with multislice CT (MSCT) used as reference. The voxel values from CBCT were measured by the obtained images with OsiriX software (http://www.osirix-viewer.com), and compared with the CT numbers from MSCT. We examined the correlation between the voxel values and the HA contents, the variance of voxel values, and the influence of changing surrounding circumstances on the voxel values. RESULTS: The voxel values from CBCT were different from the CT numbers from MSCT, but there was a linear Pearson correlation between the voxel values and the HA contents. The voxel values were greatly influenced when the samples were scanned surrounded in air. However, the voxel values were not affected significantly in the existence of materials simulating oral hard tissues and/or a metal core post. CONCLUSIONS: There was a linear correlation between the voxel values of CBCT and the contents of HA rod samples. Our study indicated that it might be possible to evaluate bone mineral content(BMC) from the voxel values of CBCT for dental implant treatment.

Preoperative evaluation of patients with squamous cell carcinoma of the oral cavity: fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography and ultrasonography versus histopathology.

BACKGROUND: The purpose of this retrospective study was to compare fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) and ultrasonography (US) in the staging of patients with squamous cell carcinoma of the oral cavity. METHODS: We compared preoperative evaluations regarding lymph nodes using PET/CT, US, and both methods. The cutoff for the maximum standardized uptake value (SUV(max)) in PET/CT was set at 2.7 by a receiver operating characteristic analysis that was based on the histopathological diagnosis. US was used to examine internal structural changes on B-mode and hilar vascularity on power Doppler. RESULTS: The performance of PET/CT and US in combination was better than that of each modality separately. However, there were histopathological changes that could not be detected on PET/CT or US. PET/CT could not detect nodes with necrotic or cystic changes. US could not detect lymph nodes that did not have abnormal structures. CONCLUSIONS: PET/CT and US are complementary tools to evaluate preoperative patients.