Correlation between diffusion-weighted image-derived parameters and dynamic contrast-enhanced magnetic resonance imaging-derived parameters in the orofacial region.

Background: Diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) are widely used in the orofacial region. Furthermore, quantitative analyses have proven useful. However, a few reports have described the correlation between DWI-derived parameters and DCE-MRI-derived parameters, and the results have been controversial. Purpose: To evaluate the correlation among parameters obtained by DWI and DCE-MRI and to compare them between benign and malignant lesions. Material and Methods: Fifty orofacial lesions were analysed. The apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudodiffusion coefficient (D*) and perfusion fraction (f) were estimated by DWI. For DCE-MRI, TK model analysis was performed to estimate physiological parameters, for example, the influx forward volume transfer constant into the extracellular-extravascular space (EES) (Ktrans) and fractional volumes of EES and plasma components (ve and vp). Results: Both ADC and D showed a moderate positive correlation with ve (ρ = 0.640 and 0.645, respectively). Ktrans showed a marginally weak correlation with f (ρ = 0.296), while vp was not correlated with f or D*; therefore, IVIM perfusion-related parameters and TK model perfusion-related parameters were not straightforward. Both D and ve yielded high diagnostic power between benign lesions and malignant tumours with areas under the curve (AUCs) of 0.830 and 0.782, respectively. Conclusion: Both D and ve were reliable parameters that were useful for the differential diagnosis. In addition, the true diffusion coefficient (D) was affected by the fractional volume of EES.

Submandibular gland carcinoma ex pleomorphic adenoma with calcification.

We report an unusual case of carcinoma ex pleomorphic adenoma (CXPA) in the submandibular gland. The mass had a unique calcification. Panoramic tomography revealed sponge-like calcification. The central portion displayed heterogeneous high signal intensity on T1-weighted image (T1WI) and T2-weighted image (T2WI), and heterogeneously moderate signal intensity on a short-TI inversion recovery (STIR) image. The ADC was low (0.78 × 10-3mm2/sec). After surgical excision, a pathological examination revealed that the mass contained CXPA as a minor component. Tumor cells with large hyperchromatic nuclei and eosinophilic or clear cytoplasm proliferated in irregular small tubule formations or cribriform or Roman-bridge structures in hyalinized or focally ossified stroma. The entire mass was calcified, particularly in the central region. Taken together, the reduced T1 relaxation times were related to the surface effects of diamagnetic particles, which were observed at calcium particle concentrations of up to 30%. We report a CXPA with unusual sponge-like calcification, which appeared unusually hyperintense on T1WI due to a surface effect.

Intraosseous synovial sarcoma of the mandible: A case report and review of the literature.

Synovial sarcoma (SS) is a malignant soft tissue tumor that usually arises in the para-articular regions of the extremities. Only nine cases of SS in the mandible have been reported to date. The present study described a case of SS arising from the left mandible. A 54-year-old woman was referred to Kyushu University Hospital (Fukuoka, Japan) with a complaint of numbness in the left mental nerve area. Computed tomography revealed replacement of the left mandibular bone marrow with soft tissue and destruction of the mandibular canal. Magnetic resonance imaging revealed an isointense mass on T1-weighted images and hyperintensity on T2-weighted images. The tumor showed homogeneous enhancement. A biopsy was performed, and monophasic SS was diagnosed based on immunohistochemical staining features and genetic analysis. Hemimandible dissection and supraomophyoid neck resection were performed with fibular osteocutaneous flap reconstruction, followed by adjuvant chemotherapy. There was no evidence of recurrence or distant metastases. The present study also reviewed the clinical, imaging, histological, and immunohistochemical features of the SS in the mandible.

Usefulness of reconstructed images of Gd-enhanced 3D gradient echo sequences with compressed sensing for mandibular cancer diagnosis: comparison with CT images and histopathological findings.

OBJECTIVES: To compare the delineation of mandibular cancer by 3D T1 turbo field echo with compressed SENSE (CS-3D-T1TFE) images and MDCT images, and to compare both sets of images with histopathological findings, as the gold standard, to validate the accuracy and clinical usefulness of CS-3D-T1TFE reconstruction. METHODS: Twenty-four patients with mandibular squamous cell carcinoma (SCC) who underwent MRI including CS-3D-T1TFE and MDCT examinations before surgery were retrospectively included. For both examinations, 0.5-mm-thick coronal plane images and 0.5-mm-thick plane images perpendicular and parallel to the dentition were constructed. Two radiologists rated bone invasion in three categories indexed by cortical bone, cancellous bone, and mandibular canal (MC), and inter-rater agreement was assessed by weighted kappa statistics. In 20 of the 24 patients who underwent surgery, the correlation of bone invasion with the histopathological evaluation by pathologists was assessed using Pearson's correlation coefficient. Soft-tissue invasion was assessed by diagnosing the presence of invasion into the mylohyoid muscle, gingivobuccal fold, and masticator space, and inter-rater agreement was assessed by kappa statistics. RESULTS: The interobserver agreement for bone invasion assessment was almost perfect with CS-3D-T1TFE and substantial with MDCT. The image evaluations by both observers agreed with the pathological evaluations in 15 of the 20 cases, showing high correlation (r > 0.8). CS-3D-T1TFE also showed higher inter-rater agreement than MDCT for all measures of soft-tissue invasion. CONCLUSIONS: CS-3D-T1TFE reconstructed images were clinically useful in accurately depicting the extent of mandibular cancer invasion and potentially solving the problem of lesion overestimation associated with conventional MRI. KEY POINTS: • Reconstructed CS-3D-T1TFE images were useful for the diagnosis of mandibular cancer. • CS-3D-T1TFE images showed higher inter-rater agreement than MDCT and high correlation with pathological findings. • CS-3D-T1TFE images may solve the problem of overestimation of the tumor extent, which has been associated with MRI in the past.

Lipomatous mixed tumor of the skin with cystic formation affecting the upper lip: A case report.

Mixed tumor of the skin (MTS) is a rare neoplasm derived from the sweat glands with a reported frequency of 0.01-0.098% among all primary skin tumors. MTS often occurs in the head and neck region and is characterized by a mixture of epithelial, myoepithelial and stromal components. MTS also shows various morphological patterns, thus the presence of variants with rare components and its rarity make the clinical diagnosis even more difficult. A 47-year-old man was referred due to a painless, slowly growing, exophytic swelling intracutaneous mass of the upper lip. Magnetic resonance imaging revealed that the mass was a solid tumor with a fatty component in the proximal portion, while the distal portion was cystic and possibly contained highly viscous fluid. The mass was located between the skin and the orbicularis oris muscle in the upper lip. Excisional biopsy was performed and the lesion showed two intriguing features: A tumor with extensive lipomatous stroma and some large cysts. It was histopathologically diagnosed as lipomatous MTS with cystic formation in the upper lip. No evident signs of recurrence were observed during follow-up. The present report describes this case and includes a brief literature review of reported cases in the lip, since MTS can be confused with various skin lesions in clinical settings due to this rarity. Recognition by clinicians of different variants of MTSs, including the present case, is important for preventing erroneous diagnosis and treatment.

Gamma distribution model of diffusion MRI for evaluating the isocitrate dehydrogenase mutation status of glioblastomas.

OBJECTIVE: To determine whether the γ distribution (GD) model of diffusion MRI is useful in the evaluation of the isocitrate dehydrogenase (IDH) mutation status of glioblastomas. METHODS: 12 patients with IDH-mutant glioblastomas and 54 patients with IDH-wildtype glioblastomas were imaged with diffusion-weighted imaging using 13 b-values from 0 to 1000 s/mm2. The shape parameter (κ) and scale parameter (θ) were obtained with the GD model. Fractions of three different areas under the probability density function curve (f1, f2, f3) were defined as follows: f1, diffusion coefficient (D) < 1.0×10-3 mm2/s; f2, D > 1.0×10-3 and <3.0×10-3 mm2/s; f3, D > 3.0 × 10-3 mm2/s. The GD model-derived parameters measured in gadolinium-enhancing lesions were compared between the IDH-mutant and IDH-wildtype groups. Receiver operating curve analyses were performed to assess the parameters' diagnostic performances. RESULTS: The IDH-mutant group's f1 (0.474 ± 0.143) was significantly larger than the IDH-wildtype group's (0.347 ± 0.122, p = 0.0024). The IDH-mutant group's f2 (0.417 ± 0.131) was significantly smaller than the IDH-wildtype group's (0.504 ± 0.126, p = 0.036). The IDH-mutant group's f3 (0.109 ± 0.060) was significantly smaller than the IDH-wildtype group's (0.149 ± 0.063, p = 0.0466). The f1 showed the best diagnostic performance among the GD model-derived parameters with the area under the curve value of 0.753. CONCLUSION: The GD model could well describe the pathological features of IDH-mutant and IDH-wildtype glioblastomas, and was useful in the differentiation of these tumors. ADVANCES IN KNOWLEDGE: Diffusion MRI based on the γ distribution model could well describe the pathological features of IDH-mutant and IDH-wildtype glioblastomas, and its use enabled the significant differentiation of these tumors. The γ distribution model may contribute to the non-invasive identification of the IDH mutation status based on histological viewpoint.

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. We analysed the correlations and compared the effectiveness in the differential diagnosis among the parameters of GD model (κ, shape parameter; θ, scale parameter; fractions of diffusion: ƒ1, cellular component; ƒ2, extracellular diffusion; ƒ3, perfusion component), IVIM model (D, true diffusion coefficient; D*, pseudodiffusion coefficient; f, perfusion fraction), and ME model (apparent diffusion coefficient, ADC). RESULTS: The GD and IVIM models showed a better goodness-of-fit than the ME model (p < 0.05). ƒ1 had strong negative correlations with D and ADC (ρ = -0.901 and -0.937, respectively), while ƒ3 had a moderate positive correlation with f (ρ = 0.661). Malignant entity presented significantly higher ƒ1 and lower D and ADC than benign entity (p < 0.0001). Malignant lymphoma had significantly higher ƒ1 in comparison to squamous cell carcinoma (p = 0.0007) and granulation (p = 0.0075). The trend in ƒ1 was opposite to the trend in D. Malignant lymphoma had significant lower ƒ3 than squamous cell carcinoma (p = 0.005) or granulation (p = 0.0075). CONCLUSIONS: The strong correlations were found between the GD- and IVIM-derived parameters. Furthermore, the GD model's parameters were useful for characterising the pathological structure in orofacial lesions.

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. The shape parameter (κ), scale parameter (θ), ratio of the intracellular diffusion (ƒ1), extracellular diffusion (ƒ2) and perfusion (ƒ3) were obtained by the GD model; the true diffusion coefficient (D) and perfusion fraction (f) were obtained by the IVIM model; and the apparent diffusion coefficient (ADC) was obtained by the ME model. RESULTS: ƒ1 had a strongly negative correlation with the ADC (ρ = -0.993) and D (ρ = -0.926). A strong positive correlation between f and ƒ3 (ρ = 0.709) was found. Malignant lymphoma (ML) had the highest ƒ1, followed by squamous cell carcinoma (SCC), malignant salivary gland tumours, pleomorphic adenoma (Pleo) and angioma. Both the IVIM and GD models suggested the highest perfusion in angioma and the lowest perfusion in ML. The GD model demonstrated a high extracellular component in Pleo and revealed that the T4a+T4b SCC group had a lower ƒ2 than the T2+T3 SCC group, and poor to moderately differentiated SCC had a higher ƒ1 than highly differentiated SCC. CONCLUSIONS: Given the correlation among the diffusion-derived parameters, the GD model might be a good alternative to the IVIM model. Furthermore, the GD model's parameters were useful for characterizing the pathological structure.

X-ray dose reduction using additional copper filtration for dental cone beam CT.

This study aims to quantitatively evaluate the effect of additional copper-filters (Cu-filters) on the radiation dose and contrast-to-noise ratio (CNR) in a dental cone beam computed tomography (CBCT). The Cu-filter thickness and tube voltage of the CBCT unit were varied in the range of 0.00-0.20 mm and 70-90 kV, respectively. The CBCT images of a phantom with homogeneous materials of aluminum, air, and bone equivalent material (BEM) were acquired. The CNRs were calculated from the voxel values of each homogeneous material. The CTDIvol was measured using standard polymethyl methacrylate CTDI test objects. We evaluated and analyzed the effects of tube current and various radiation qualities on the CNRs and CTDIvol. We observed a tendency for higher CNR at increasing tube voltage and tube current in all the homogeneous materials. On the other hand, the CNR reduced at increasing Cu-filter thickness. The tube voltage of 90 kV showed a clear advantage in the tube current-CNR curves in all the homogeneous materials. The CTDIvol increased as the tube voltage and tube current increased and decreased with the increase in the Cu-filter thickness. When the CNR was fixed at 9.23 of BEM at an exposure setting of 90 kV/5 mA without a Cu-filter, the CTDIvol at 90 kV with Cu-filters was 8.7% lower compared with that at 90 kV without a Cu-filter. The results from this study demonstrate the potential of adding a Cu-filter for patient dose reduction while ensuring the image quality.

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 shape parameter (κ) and scale parameter (θ) were obtained with the GD model. Fractions of three different areas under the probability density function curve (f1, f2, f3) were defined as follows: f1, diffusion coefficient (D) <1.0×10-3 mm2/sec; f2, D >1.0×10-3 and <3.0×10-3 mm2/sec; f3, D >3.0 × 10-3 mm2/sec. The GD model-derived parameters were compared between PCNSLs and GBs. Receiver operating characteristic (ROC) curve analyses were performed to assess diagnostic performance. The correlations with intravoxel incoherent motion (IVIM)-derived parameters were evaluated. The PCNSL group's κ (2.26 ± 1.00) was significantly smaller than the GB group's (3.62 ± 2.01, p = 0.0004). The PCNSL group's f1 (0.542 ± 0.107) was significantly larger than the GB group's (0.348 ± 0.132, p<0.0001). The PCNSL group's f2 (0.372 ± 0.098) was significantly smaller than the GB group's (0.508 ± 0.127, p<0.0001). The PCNSL group's f3 (0.086 ± 0.043) was significantly smaller than the GB group's (0.144 ± 0.062, p<0.0001). The combination of κ, f1, and f3 showed excellent diagnostic performance (area under the curve, 0.909). The f1 had an almost perfect inverse correlation with D. The f2 and f3 had very strong positive correlations with D and f, respectively. The GD model is useful for the differentiation of GBs and PCNSLs.

Comparison of image quality of head and neck lesions between 3D gradient echo sequences with compressed sensing and the multi-slice spin echo sequence.

BACKGROUND: Although magnetic resonance imaging (MRI) provides excellent soft-tissue contrast, long acquisition times are major disadvantages. PURPOSE: To evaluate the usefulness of compressed sensing (CS) for contrast-enhanced oral and maxillofacial MRI by comparing the 3D T1 turbo field echo with compressed SENSE (CS-3D-T1TFE) sequence with the multi-slice spin echo (MS-SE) sequence as the reference standard. MATERIAL AND METHODS: Thirty patients with orofacial lesions participated in this study. The scan times for MS-SE and CS-3D-T1TFE were 5 min 56 s and 1 min 43 s, respectively. The signal-to-noise ratio (SNR) was calculated for quantitative analysis and seven parameters (degree of lesion conspicuity, motion artifacts, metal artifacts, pulsation artifacts, quality of fat suppression, homogeneity of blood vessel signal intensity, and overall image quality) were evaluated using a 5-point scale (5 = excellent, 1 = unacceptable) by two observers for qualitative analysis. For comparisons between MS-SE and CS-3D-T1TFE, the paired t-test was used. RESULTS: The SNR of CS-3D-T1TFE was higher than or equal to that of MS-SE. The CS-3D-T1TFE scores for motion artifacts, pulsation artifacts, and homogeneity of blood vessel signal intensity were higher than the corresponding MS-SE scores in assessments by both observers. The MS-SE scores for fat suppression were higher than or equal to the CS-3D-T1TFE scores. There were no significant differences in lesion conspicuity, metal artifacts, and overall image quality between the two sequences. CONCLUSION: CS-3D-T1TFE imaging, less than 30% of the scan time for MS-SE, showed no image degradation while retaining equal or higher SNR and image quality.

Image Quality and ADC Assessment in Turbo Spin-Echo and Echo-Planar Diffusion-Weighted MR Imaging of Tumors of the Head and Neck.

RATIONALE AND OBJECTIVES: We aimed to compare the distortion ratio (DR), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) between turbo spin-echo (TSE)-diffusion-weighted imaging (DWI) and echo-planar imaging (EPI)-DWI of the orofacial region and prove the usefulness of TSE-DWI for the differential diagnosis of orofacial lesions. MATERIALS AND METHODS: The DR, SNR, and CNR of both sequences were compared in 42 cases. Then, the apparent diffusion coefficient (ADC) of various orofacial lesions obtained by TSE-DWI was investigated in 143 lesions. RESULTS: In the first study, 38 of 42 cases were analyzed. TSE-DWI showed a significantly lower DR (p < 0.05) and higher SNR and CNR than EPI-DWI (p < 0.05), indicating the superiority of TSE-DWI. In the second study, 114 cases (79.3%) were successfully analyzed. When lesions were divided into cysts, benign tumors, squamous cell carcinoma, malignant lymphoma, and other malignant tumors (OT), significant differences were observed in all pairs of lesions (p < 0.05) except squamous cell carcinoma and OT (p = 0.877). The area under the curve for distinguishing benign from malignant tumors was 0.80 with a cutoff ADC of 1.29 × 10-3 mm²/s. CONCLUSION: TSE-DWI produced better quality images than EPI-DWI. TSE-DWI yields the high possibility of obtaining ADC in the orofacial region, and this value was considered useful for the differential diagnosis of orofacial lesions.

Clinical guidelines for dental cone-beam computed tomography.

Dental cone-beam computed tomography (CBCT) received regulatory approval in Japan in 2000 and has been widely used since being approved for coverage by the National Health Insurance system in 2012. This imaging technique allows dental practitioners to observe and diagnose lesions in the dental hard tissue in three dimensions (3D). When performing routine radiography, the examination must be justified, and optimal protection should be provided according to the ALARA (as low as reasonably achievable) principles laid down by the International Commission on Radiological Protection. Dental CBCT should be performed in such a way that the radiation exposure is minimized and the benefits to the patient are maximized. There is a growing demand for widespread access to cutting-edge health care through Japan's universal health insurance system. However, at the same time, people want our limited human, material, and financial resources to be used efficiently while providing safe health care at the least possible cost to society. Japan's aging population is expected to reach a peak in 2025, when most of the baby boomer generation will be aged 75 years or older. Comprehensive health care networks are needed to overcome these challenges. Against this background, we hope that this text will contribute to the nation's oral health by encouraging efficient use of dental CBCT.

Estimation of proton density fat fraction of the salivary gland.

OBJECTIVE: Our first objective was to prove the validity of the six-point Dixon method for estimating the proton density fat fraction (PDFF) of the salivary gland. The second objective was to estimate the salivary gland PDFF using Dixon method to evaluate the pathological conditions. METHODS: At first, 12 volunteers underwent two types of sequences: single-voxel magnetic resonance spectroscopy and the Dixon method and the PDFFs obtained by the two methods were compared. Next, a total of 67 individuals [normal, n = 46; Sjögren's syndrome (SS), n = 11; and IgG4-related dacryoadenitis and sialadenitis (IgG4-DS), n = 4, parotitis, n = 6] were enrolled to estimate the parotid gland (PG) and submandibular gland (SMG) PDFF using the Dixon method. RESULTS: This volunteer study demonstrated excellent correlation between two methods (R2 = 0.964, slope = 1.05). In the normal group, the PG-PDFF was correlated with the weight and body mass index (BMI) (ρ = 0.38, p = 0.0085; and ρ = 0.63, p < 0.0001). The SMG-PDFF was also correlated with the weight, BMI, and serum triglyceride (ρ = 0.37, p = 0.0067; ρ = 0.42, p = 0.0022; and ρ = 0.35, p = 0.024). The PG-PDFF of the SS group (48.2 ± 15.1%) was higher than that of any other groups; however, no significant difference was found due to the wide overlap. The SS group (39.0 ± 26.14%) also had significantly higher SMG-PDFF than the normal group (8.9 ± 5.4%), p < 0.0001) and IgG4-DS group (3.8 ± 2.3%), p = 0.020). CONCLUSION: The Dixon method is a feasible method for estimating the PDFF and demonstrates fat accumulation in SMG in the SS group. Advances in knowledge: The PDFF obtained by the Dixon method is helpful for understanding the salivary gland pathological condition.

Fundamental Tongue Motions for Trumpet Playing: A Study Using Cine Magnetic Resonance Imaging (Cine MRI).

OBJECTIVE: Though the motions of structures outside the mouth in trumpet performance have been reported, the dynamics of intraoral structures remain unelucidated. This study explored the tongue's movement in trumpet playing using cine magnetic resonance imaging (cine MRI) and demonstrated the effects of intraoral anatomical structures on changes in pitch and dynamics. METHODS: Cine MRI was applied to 18 trumpet players, who were divided into two groups (7 beginner, 11 advanced) based on their ability to play a certain high note. They were instructed to play a custom-made MRI-compatible simulated trumpet. Pitch-change tasks and dynamics-change tasks were assigned. The positions of the anatomical points and intraoral areas were identified on outlined images, and the changes associated with each task were evaluated. RESULTS: A forward and upward projection of the tongue was observed in the production of higher pitches, and there were no significant differences in all areas. In louder dynamics, a backward and downward bending of the tongue occurred, the tongue area became smaller (p<0.001), and the oral cavity area became larger (p<0.001). No significant differences between beginner and advanced trumpet players were seen in the changes in pitch and dynamics. CONCLUSION: It was demonstrated using cine MRI that certain tongue movements were associated with each task. Tongue protrusion in the production of higher pitch and bending in louder dynamics can be rationalized using acoustics theory and the movements of anatomical structures. These findings seem to be consistent regardless of the player's proficiency.

Clinical usefulness of the mDIXON Quant the method for estimation of the salivary gland fat fraction: comparison with MR spectroscopy.

OBJECTIVE: To estimate the fat fraction (FF) in the salivary glands (SGs) by the mDIXON method and the 1H-MR spectroscopy (MRS) method, and to compare the results. METHODS: 16 healthy volunteers were enrolled. mDIXON Quant and MRS (point-resolved spectroscopy: PRESS) with a single TE were employed to measure the FF in the parotid gland (PG) and submandibular gland (SMG). Multiple TEs were applied in 10 volunteers to correct for T2 decay. In addition, we assumed that the 1.3 ppm peak accounted for 60% of the total fat peak and estimated the FF (MRS all) as a gold standard. On mDIXON Quant images, volumes of interest were set on the bilateral SGs and we obtained the FF (mDIXON) of each volume of interest. RESULTS: There was a strong correlation between the results of the mDIXON Quant method and the MRS (single TE) method (R2 = 0.960, slope = 0.900). Using PRESS with multiple TEs, there was also a strong correlation between FF (mDIXON) and FF (MRS all) (R2 = 0.963, slope = 1.18). FF (MRS all) was 24.9±12.7% in the PG and 4.5±3.0% in the SMG, while FF (mDIXON) was 29.4±16.2% in the PG and 6.4±4.7% in the SMG. There were no significant differences between the two methods, but the Bland-Altman plot showed that FF (mDIXON) was slightly larger than FF (MRS all) for small FF areas. CONCLUSION: The mDIXON Quant method could be clinically useful for evaluating the FF of SGs, but the absolute values need careful interpretation. Advance in knowledge: This study suggested the potential clinical usefulness of the mDIXON Quant method for the SGs.

Clinicopathological evaluation of pre-operative chemoradiotherapy with S-1 as a treatment for locally advanced oral squamous cell carcinoma.

The administration of pre-operative chemotherapy with S-1 and concurrent radiotherapy at a total dose of 30 Gy was clinicopathologically evaluated as a treatment for locally advanced oral squamous cell carcinoma (OSCC) in the present study. The participants comprised 81 patients with OSCC, consisting of 29 patients with stage II disease, 12 patients with stage III disease and 40 patients with stage IV disease. All patients received a total radiation dose of 30 Gy in daily fractions of 2 Gy, 5 times a week, for 3 weeks, and the patients were concurrently administered S-1 at a dose of 80-120 mg, twice daily, over 4 consecutive weeks. Radical surgery was performed in all cases at 2-6 weeks subsequent to the end of pre-operative chemoradiotherapy. The most common adverse event was oropharyngeal mucositis, but this was transient in all patients. No severe hematological or non-hematological toxicities were observed. The clinical and histopathological response rates were 70.4 and 75.3%, respectively. Post-operatively, local failure developed in 6 patients (7.4%) and neck failure developed in 2 patients (2.5%). Distant metastases were found in 7 patients (8.6%). The overall survival rate, disease-specific survival rate and locoregional control rate at 5 years were 87.7, 89.9 and 90.6%, respectively. Locoregional recurrence occurred more frequently in patients that demonstrated a poor histopathological response compared with patients that demonstrated a good response (P<0.01). These results indicate that pre-operative S-1 chemotherapy with radiotherapy at a total dose of 30 Gy is feasible and effective for patients with locally advanced OSCC, and that little or no histopathological response may be a risk factor for locoregional recurrence in this treatment.

A case of mantle cell lymphoma presenting as IgG4-related dacryoadenitis and sialoadenitis, so-called Mikulicz's disease.

BACKGROUND: Mantle cell lymphoma (MCL) is a relatively uncommon type of non-Hodgkin lymphoma. It develops in the outer edge of a lymph node called the mantle zone. In contrast, IgG4-related dacryoadenitis and sialoadenitis (IgG4-DS) is characterized by elevated serum IgG4 and persistent bilateral enlargement of lacrimal glands (LGs) and salivary glands (SGs), with infiltration of IgG4-positive plasma cells. Recent studies indicated the importance of differentiation between IgG4-DS and malignant lymphoma. CASE PRESENTATION: An 82-year-old man was suspected of IgG4-DS because of a high serum IgG level (2174 mg/dL) and bilateral swelling of LGs and SGs. Lip biopsy and fine needle biopsy of submandibular gland were performed, and subsequently, MCL was diagnosed through the histopathological findings. CONCLUSIONS: MCL most commonly occurs in the Waldeyer ring, but rarely in the stomach, spleen, skin, LG, and SG. We report an unusual case of MCL involving LGs and SGs mimicking IgG4-DS, which suggests that IgG4 testing may be useful in the differentiation of IgG4-DS in the presence of bilateral swelling of LGs or SGs.

Case of mucoepidermoid carcinoma of the sublingual gland accompanied with extensive dystrophic calcification and intratumoral bone formation.

BACKGROUND: Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy. Although the histopathological findings are diverse, no case of salivary MEC accompanied with bone formation has been reported. Herein, we present the first case of MEC with intratumoral bone formation. METHODS AND RESULTS: A case of a 75-year-old female patient with an asymptomatic mass of the oral floor is presented. Enhanced CT revealed a tumorous mass with radiopaque materials in the oral floor. A pathological diagnosis of MEC was obtained by biopsy. Radical surgery was performed with the patient under general anesthesia. The resected specimen was finally diagnosed as MEC. Histopathologically, hyalinization, and dystrophic calcification were conspicuous within the stromal components of the tumor. Interestingly, ectopic bone formation was also found in the tumor tissues. Bony materials with osteocyte-like cells were also observed in a series of dystrophic calcification. CONCLUSION: These findings suggest that bony materials are associated with dystrophic calcification.

The application of dynamic contrast-enhanced MRI and diffusion-weighted MRI in patients with maxillofacial tumors.

RATIONALE AND OBJECTIVES: To elucidate the characteristics of four types of tumors, including squamous cell carcinoma (SCC), malignant lymphoma (ML), malignant salivary gland tumors (MSGTs), and pleomorphic adenoma (Pleo), in the maxillofacial region using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion-weighted MRI (DW-MRI）data. MATERIALS AND METHODS: A total of 59 tumors were included in this research. DCE-MRI and DW-MRI were performed. We applied the Tofts and Kermode model (TK model) for the DCE-MRI data and obtained three dependent parameters: the influx forward volume transfer constant into the extravascular extracellular space from the plasma (K(trans)), the fractional volume of extravascular extracellular space per unit volume of tissue (ve), and the fractional volume of plasma (vp). RESULTS: Among the K(trans) values, there were no significant differences between the three types of malignant tumors; however, there was a significant difference between the SCC and Pleo (P = .0099). The ve values of the Pleo were highest, with significant differences compared to the other categories (SCC, P = .0012; ML, P = .0017; and MSGT, P = .041). The ML had the lowest ve values, and there were significant differences between ML and the other two types of malignant tumors (SCC, P = .0278 and MSGT, P = .0062). In 14 (24%) cases, apparent diffusion coefficient (ADC) could not be measured because of poor image quality. The ADC values of the ML were lowest, whereas those of Pleo were highest, similar to that observed for ve. CONCLUSIONS: The Pleo tumors had lower K(trans) values and higher ve values, which are useful for differentiating them from the malignant tumors. Moreover, the ve was also useful for establishing a diagnosis of ML.