Estimation of whole-body radiation exposure from brachytherapy for oral cancer using a Monte Carlo simulation.

Early stage oral cancer can be cured with oral brachytherapy, but whole-body radiation exposure status has not been previously studied. Recently, the International Commission on Radiological Protection Committee (ICRP) recommended the use of ICRP phantoms to estimate radiation exposure from external and internal radiation sources. In this study, we used a Monte Carlo simulation with ICRP phantoms to estimate whole-body exposure from oral brachytherapy. We used a Particle and Heavy Ion Transport code System (PHITS) to model oral brachytherapy with 192Ir hairpins and 198Au grains and to perform a Monte Carlo simulation on the ICRP adult reference computational phantoms. To confirm the simulations, we also computed local dose distributions from these small sources, and compared them with the results from Oncentra manual Low Dose Rate Treatment Planning (mLDR) software which is used in day-to-day clinical practice. We successfully obtained data on absorbed dose for each organ in males and females. Sex-averaged equivalent doses were 0.547 and 0.710 Sv with 192Ir hairpins and 198Au grains, respectively. Simulation with PHITS was reliable when compared with an alternative computational technique using mLDR software. We concluded that the absorbed dose for each organ and whole-body exposure from oral brachytherapy can be estimated with Monte Carlo simulation using PHITS on ICRP reference phantoms. Effective doses for patients with oral cancer were obtained.

Differentiating benign and malignant salivary gland tumours: diagnostic criteria and the accuracy of dynamic contrast-enhanced MRI with high temporal resolution.

OBJECTIVE: To determine the optimal diagnostic criterion of dynamic contrast-enhanced MRI (DCE-MRI) for predicting salivary gland malignancy using a dynamic sequence with high temporal resolution, as well as the accuracy of this technique. METHODS: The DCE-MRI findings of 98 salivary gland tumours (74 benign and 24 malignant) were reviewed. MR images were sequentially obtained at 5-s intervals for 370 s. Two parameters, peak time and washout ratio (WR) were determined from the time-signal intensity curve. The optimal thresholds of these parameters for differentiating benign and malignant tumours were determined, along with the diagnostic accuracy of the criterion using these thresholds. RESULTS: A peak time of 150 s and a WR of 30% were identified as optimal thresholds. As the criterion for malignancy, the combination of peak time <150 s and WR <30% provided a sensitivity of 79% (19/24), specificity of 95% (70/74) and an overall accuracy of 91% (89/98). Three of the five false-negative cases were malignant lymphomas of the parotid gland. CONCLUSION: Peak time <150 s with WR <30% comprised the optimal diagnostic criterion in predicting salivary gland malignancy, providing a sensitivity of 79% and specificity of 95%. The use of high temporal resolution might improve the accuracy of DCE-MRI. ADVANCES IN KNOWLEDGE: Although several studies have reported the usefulness of DCE-MRI in the differential diagnosis of salivary gland tumours, the specific diagnostic criteria employed have differed widely. We determined the optimal criterion and its accuracy using a dynamic sequence with high temporal resolution.

MRI characteristics of rheumatoid arthritis in the temporomandibular joint.

OBJECTIVES: The aim of this study was 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.

Acute generalized exanthematous pustulosis during the puerperal period: a case report.

BACKGROUND: Acute generalized exanthematous pustulosis (AGEP) is an uncommon adverse cutaneous reaction, most commonly associated with drugs. CASE: A 38-year-old primigravida whose labor had been induced developed erythema over her chest and abdomen. She was transferred to our department after a failed vacuum extraction, and delivered a mature infant by forceps. On day three postpartum she developed a 40.4 degrees C fever. Although ceftriaxone was administered, her fever persisted (>38 degreesC). On day six of the puerperium, diffuse non-follicular pustules appeared over her neck and trunk, and AGEP was suspected. Two days after ceftriaxone was withdrawn, the eruptions started to resolve without any medical intervention. CONCLUSION: Once the diagnosis of AGEP has been made, the antibiotics being administered must be discontinued. If continued treatment is required, pharmacologically distinct antibiotics must be used instead to aid the rapid self-limitation of the disease.

A clinicoradiological study of odontogenic carcinomas and their impact on clinical diagnosis.

OBJECTIVES: To investigate the clinical and radiological characteristics of odontogenic carcinomas (OCs) and evaluate their impact on early clinical diagnosis. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

USPIO-enhanced MRI of highly invasive and highly metastasizing transplanted human squamous cell carcinoma: an experimental study.

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Application of MRI movie for observation of articulatory movement during a fricative /s/ and a plosive /t/.

OBJECTIVE: To use an accurate method of tooth visualization in magnetic resonance imaging (MRI) movie for the observation of spatio-temporal relationships among articulators. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Intrauterine fetal demise due to streptococcal toxic shock syndrome: a case report.

BACKGROUND: Toxic shock syndrome caused by group A streptococci (GAS) is rare around the time of delivery, but it may predispose pregnant women to a life-threatening condition. CASE: A 32-year-old primigravida at 21 weeks of gestation was taken to our hospital with acute severe abdominal pain following fever. On admission the fetus was found to be dead, and intrauterine fetal demise due to placental abruption was suspected. An emergency cesarean section found no sign of placental abruption. Soon after the surgery, the patient went into shock but was successfully treated with intensive care. Although repeated blood cultures failed to detect microorganisms, the patient was positive for streptococcal pyrogenic toxin A, which is a superantigen of GAS. CONCLUSION: Once GAS infection is suspected, regardless of negative blood cultures, supportive care in the intensive care unit is mandatory.

Usefulness of cone beam computed tomography in temporomandibular joints with soft tissue pathology.

OBJECTIVE: the aim of the study was to evaluate the usefulness of cone beam CT (CBCT) in temporomandibular joints (TMJs) with soft tissue pathology. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Diagnostic performance of magnetic resonance imaging for detecting osseous abnormalities of the temporomandibular joint and its correlation with cone beam computed tomography.

OBJECTIVE: 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). METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Bifid mandibular canals: cone beam computed tomography evaluation.

OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Modulation transfer function evaluation of cone beam computed tomography for dental use with the oversampling method.

OBJECTIVES: The aim was to investigate the possibility of evaluating the modulation transfer function (MTF) of cone beam CT (CBCT) for dental use using the oversampling method. METHODS: The CBCT apparatus (3D Accuitomo) with an image intensifier was used with a 100 mum tungsten wire placed inside the scanner at a slight angle to the plane perpendicular to the plane of interest and scanned. 200 contiguous reconstructed images were used to obtain the oversampling line-spread function (LSF). The MTF curve was obtained by computing the Fourier transformation from the oversampled LSF. Line pair tests were also performed using Catphan(R). RESULTS: The oversampling method provided smooth and reproducible MTF curves. The MTF curves revealed that the spatial resolution in the z-axis direction was significantly higher than that in the axial direction. This result was also confirmed by the line pair test. CONCLUSIONS: MTF analysis was performed successfully using the oversampling method. In addition, this study clarified that the 3D Accuitomo had high spatial resolution, especially in the z-axis direction.

Differentiation between superficial and deep lobe parotid tumors by magnetic resonance imaging: usefulness of the parotid duct criterion.

BACKGROUND: The location of a parotid tumor affects the choice of surgery, and there is a risk of damaging the facial nerve during surgery. Thus, differentiation between superficial and deep lobe parotid tumors is important for appropriate surgical planning. PURPOSE: To evaluate the usefulness of using the parotid duct, in addition to the retromandibular vein, for differentiating between superficial and deep lobe parotid tumors on MR images. MATERIAL AND METHODS: Magnetic resonance images of 42 parotid tumors in 40 patients were reviewed to determine whether the tumor was located in the superficial or deep lobe. In each case, the retromandibular vein and the parotid duct were used to locate the tumor. The parotid duct was only used in cases where the tumor and the duct were visualized on the same image. RESULTS: Using the retromandibular vein criterion, 71% of deep lobe and 86% of superficial lobe tumors were correctly diagnosed, providing an accuracy of 81%. However, the accuracy achieved when using the parotid duct criterion was 100%, although it could be applied to only 28 of the 42 cases. Based on these results, we defined the following diagnostic method: the parotid duct criterion is first applied, and for cases in which it cannot be applied, the retromandibular vein criterion is used. The accuracy of this method was 88%, which was better than that achieved using the retromandibular vein criterion alone. CONCLUSION: The parotid duct criterion is useful for determining the location of parotid tumors. Combining the parotid duct criterion with the retromandibular vein criterion might improve the diagnostic accuracy of parotid tumor location compared to using the latter criterion alone.

Correlation of darkening of impacted mandibular third molar root on digital panoramic images with cone beam computed tomography findings.

OBJECTIVES: Darkening of the lower third molar root on panoramic images is known to indicate an intimate relationship between the root and mandibular canal. The objective of this study was to investigate the anatomical relationship between the third molar root and its surrounding structures that leads to this panoramic finding. METHODS: Imaging findings of 253 impacted lower third molars examined by both digital panoramic radiography and cone beam CT were reviewed. Panoramic images were evaluated to detect the presence or absence of darkening of the root where the mandibular canal was superimposed. Cone beam CT images were evaluated for the presence or absence of the following two findings: (1) grooving of the root and (2) thinning or perforation of the cortical plate by the root. The correlation between the panoramic and cone beam CT findings was examined using logistic regression analysis. RESULTS: 80 (32%) third molars showed a panoramic finding of darkening of the root. Between cone beam CT findings, cortical thinning or perforation alone was significantly correlated with this panoramic finding (80%, P < 0.001). CONCLUSIONS: The panoramic finding of mandibular third molar root darkening was considered to reflect cortical thinning or perforation rather than grooving of the root.

An investigation of magnetic resonance imaging features in 14 patients with synovial chondromatosis of the temporomandibular joint.

OBJECTIVES: To show the characteristic MRI features of synovial chondromatosis (SC) of the temporomandibular joint (TMJ). METHODS: All patients with histologically proven SC of the TMJ who underwent MRI at our clinic were examined. In 14 patients (male-to-female ratio, 2:12; average age 46+/-14 years), clinical and conventional radiographic findings were reviewed. In addition, the MRI findings of articular disc and condyle position, shape and signal intensity of the joint spaces, and bone changes of surrounding structures were analysed. RESULTS: The main symptoms were pain (in 93% of the patients) and limitation of mouth opening (64%). Two cases showed typical multiple calcifications around the TMJ on conventional radiography. On MRI, the disc position was normal in 12 (86%) patients and the condyle was inferiorly displaced in 9 (64%) patients. 11 (79%) patients showed enlargement of the joint space, with either a "dumbbell" shape or bulging. SC in the upper compartment showed various degrees of bone changes of the articular eminence and fossa. SC in the lower compartment showed concavity or hypertrophy of the condyle. The severity of the bone changes progressed with duration of symptoms. CONCLUSIONS: About 0.3% of the patients complaining of TMJ pain and dysfunction were found to have SC. There was great variation in the MRI features of the TMJs with SC. More severe destruction of surrounding bone structures with features resembling a tumour were found in patients with a longer duration of symptoms.

Application of magnetic resonance imaging movie to assess articulatory movement.

OBJECTIVE: To introduce the technique of magnetic resonance imaging (MRI) movie and to propose its feasibility for investigating articulatory movement. SUBJECTS: Five healthy adult females participated in the study. METHODS: Dynamic changes in oropharyngeal structures were assessed with MRI movie during the articulation of a bilabial consonant. RESULTS: Movements of the velum and tongue at a time resolution of 30 ms were complex at the tip of the tongue and the anterior part of the velum. These movements that were seen with a time resolution of 30 ms could not be interpolated or in any way derived from the results obtained with a time resolution of 120 ms. CONCLUSION: The results suggest that MRI movie may be useful in the evaluation of articulation. It is important to reduce the time resolution to 30 ms to obtain images of articulators.

A potential pitfall of MR imaging for assessing mandibular invasion of squamous cell carcinoma in the oral cavity.

BACKGROUND AND PURPOSE: Whether MR imaging is superior to CT in evaluating the presence and extent of mandibular invasion by squamous cell carcinoma remains controversial. The purpose of this study was to directly compare the diagnostic accuracy of MR imaging and that of CT. METHODS: MR and CT images in 51 patients with squamous cell carcinoma of the oral cavity were evaluated for the presence and extent of mandibular invasion. The results were correlated with histopathologic findings. RESULTS: Twenty-five of 51 patients had histopathologic evidence of mandibular cortical invasion. The tumor involved both the cortex and the bone marrow in all 25 patients and involved the inferior alveolar canal in 5 patients. The sensitivity and specificity for mandibular cortical invasion were 96% and 54% for MR imaging and 100% and 88% for CT, respectively. Those for inferior alveolar canal involvement were 100% and 70% for MR imaging and 100% and 96% for CT, respectively. In both evaluations, the specificity of MR imaging was significantly lower than that of CT (McNemar test, P = .004 in the former and P = .002 in the latter). Chemical shift artifact by bone marrow fat was postulated to be the source of most false-positive cases on MR imaging findings for mandibular cortical invasion. Those for inferior alveolar canal involvement were due to MR imaging visualization of the tumor and surrounding inflammation with similar signal intensity. CONCLUSION: In assessing the presence and extent of mandibular invasion by squamous cell carcinoma, the specificity of MR imaging was significantly lower than that of CT.

CT findings as a significant predictive factor for the curability of mandibular osteomyelitis: multivariate analysis.

OBJECTIVES: To re-evaluate computed tomographic (CT) imaging as a diagnostic tool for mandibular osteomyelitis and to assess the clinical significance of CT findings. METHODS: CT images of 78 patients with mandibular osteomyelitis were reviewed. All patients were classified as cured or non-cured. Each CT finding was investigated for frequency, correlation with duration and disease cure. RESULTS: Of the 78 patients, 49 (63%) were classified as "cured" and 29 (37%) as "non-cured". Non-cured had experienced a significantly longer duration of symptoms. The most frequent CT finding was sclerosis and defect in the trabecular bone. Changes of bone width and thickening of the cortical plate were accompanied with longer disease duration. The extent of the diseased area was linearly correlated with the duration of symptoms. The significant factors to discriminate non-cured from cured were the extent of the disease, the number of findings, changes in the bone width, osteosclerosis and thickening of the cortex. Multivariate logistic regression analysis indicated that the extent of the disease and presence of changes in bone width were significant variables correlating with the cure of osteomyelitis. CONCLUSIONS: The extent of disease and the presence of change in bone width shown on CT were significantly correlated with the curability of osteomyelitis. These results indicated the usefulness and importance of CT examination for the diagnosis of mandibular osteomyelitis.

Association between single nucleotide polymorphisms of estrogen receptor alpha gene and efficacy of HRT on bone mineral density in post-menopausal Japanese women.

BACKGROUND: Although HRT for post-menopausal women can protect against bone loss, variations in bone responses exist. We studied whether single nucleotide polymorphisms (SNP) of the estrogen receptor-alpha (ERalpha) gene contribute to the effect of HRT on lumbar spine bone mineral density (BMD). METHODS: Subjects were 84 post-menopausal women who had been taking HRT for 3 years to treat osteopenia or osteoporosis. Eighteen SNP in the ERalpha gene were characterized by a single nucleotide primer extension assay. RESULTS: Genotyping of the 84 individuals revealed that all SNP were quite common, the minor allele frequency being > or = 20%. A SNP in intron 6 (IVS6+14144) was significantly associated with the response to HRT for the first 3 years after starting treatment (P = 0.043, 0.025 and 0.032 for the first, second and third years respectively). Haplotype analysis revealed that a combination of SNP IVS6+14144 and IVS4+4238 was significantly correlated with the response to HRT; women with haplotype G-G (IVS6 14144-IVS4 4238) showed a significantly higher response (P = 0.014, 0.043 and 0.010 for the first second and third year respectively). CONCLUSIONS: These results suggest that a specific SNP and the haplotype of the selected SNP could be used to predict the effect of HRT on lumbar BMD.