Diffusion-weighted imaging in the oral and maxillofacial region : usefulness of apparent diffusion coefficient maps and maximum intensity projection for characterization of normal structures and lesions

Background: The aim of this study was to investigate diffusion-weighted imaging (DWI) in the oral and maxillofacial region, with a special focus on the usefulness of apparent diffusion coefficient (ADC) maps and maximum intensity projection (MIP) for characterization of normal structures and lesions. Material/Methods: Thirty-five patients who underwent magnetic resonance imaging (MRI) for diagnosis of oral and maxillofacial lesions were included in this prospective study. DWI was performed on a 1.5 T unit, with b factor of 0 and 800 s/mm2; moreover, ADC maps were generated. ADC values were measured for normal structures, odontogenic infections, squamous cell carcinomas (SCC), and hemangiomas. Results: As regards the normal structures, the mean ADC value of the cerebrospinal fluid (3.65±0.60×10-3 mm2/s) in the upper neck area was higher than that of the spinal cord (0.74±0.15×10-3 mm2/s, P=0.000), lymph nodes (0.87±0.17×10-3 mm2/s, P=0.000), and Waldeyer’s ring (0.92±0.29×10-3 mm2/s, P=0.000). The mean ADC value of hemangiomas (1.52±0.31×10-3 mm2/s) was higher than that of odontogenic infections (0.85±0.36×10-3 mm2/s, P=0.034) and SCC (1.38±0.22×10-3 mm2/s, P=0.840). Furthermore, MIP (DWI) showed the normal structures and lesions in the oral and maxillofacial region in an improved way. Conclusions: DWI, ADC maps, and MIP can be used to characterize and differentiate normal structures and lesions in the oral and maxillofacial region

Comparison between squamous cell carcinoma and inflammatory diseases of the oral and maxillofacial region using gallium-67 scintigraphy with computed tomography and magnetic resonance imaging

Purpose: This study aimed to compare squamous cell carcinoma (SCC) with inflammatory diseases of the oral and maxillofacial region using gallium 67 (67Ga) scintigraphy with computed tomography (CT) and magnetic resonance imaging (MRI). Material and methods: Seventy patients with SCC and 15 patients with inflammatory diseases of the oral and maxillofacial region underwent 67Ga scintigraphy with CT and MRI. A comparison between imaging features of 67Ga scintigraphy, CT, and MRI and lesions was performed with the Pearson's chi-squared test. Results: 67Ga scintigraphy was positive for 25 of 39 patients with SCC positive on CT and/or MRI (64.1%) and for 13 of 15 patients with inflammatory diseases positive on CT and/or MRI (86.7%). The detection of inflammatory diseases with 67Ga scintigraphy was higher than that of SCC (p = 0.104). Conclusions: This study compared SCC with inflammatory diseases of the oral and maxillofacial region using 67Ga scintigraphy with CT and MRI. 67Ga scintigraphy is an effective technique for detection of inflammatory diseases of the oral and maxillofacial region

Characteristic multimodal imaging of medication-related osteonecrosis of the jaw : comparison between oral and parenteral routes of medication administration

Background: To assess multimodal imaging features of medication-related osteonecrosis of the jaw (MRONJ) and to analyze the differences between oral and parenteral routes of medication administration. We retrospectively reviewed panoramic radiographs, CT, MRI, and bone scintigraphy of patients with MRONJ. Material/Methods: A retrospective study was conducted in 16 patients with MRONJ who underwent panoramic radiography, CT, MRI, and bone scintigraphy. Statistical analysis for the comparison between routes of medication administration and multimodal imaging features was performed with the Pearson's c2 test. Results: The percentage of cases with sequestrum separation was 25.0% (4/16 cases) on panoramic radiography and 81.3% (13/16 cases) on CT. The percentage of cases with periosteal bone proliferation on CT was 41.7% (5/12 cases) in the oral route of administration vs. 100% (4/4 cases) in the parenteral route of administration (p=0.042). The percentage of cases with spread of soft tissue inflammation to buccal and other spaces on CT and MRI was 33.3% (4/12 cases) in the oral route of administration vs. 100% (4/4 cases) in the parenteral route of administration (p=0.021). Conclusions: The sequestrum separation on panoramic radiography in patients with MRONJ was unclear in comparison to CT. Furthermore, characteristic CT findings of patients with MRONJ in the parenteral administration group were periosteal bone proliferation and spread of soft tissue inflammation to buccal and other spaces

Structural variations in parotid glands induced by radiation therapy in patients with oral carcinoma observed on contrast-enhanced computed tomography

Background: Xerostomia is one of the commonest radiation-induced complications in patients with head and neck carcinoma. The aim of this study was to assess structural variations in parotid glands induced by radiation therapy in patients with oral carcinoma with contras-enhanced computed tomography (CECT). Material/Methods: A retrospective study was performed in 41 patients with oral carcinoma who underwent CECT for head and neck malignancies before and after radiotherapy. We analyzed the relationship between parotid density variations, parotid volume change, as seen on CECT, and the mean radiation dose applied to the parotid glands in patients with oral carcinoma immediately after radiotherapy, and 2 and 3 years later. Results: Immediately after radiotherapy, high-density changes on contrast-enhanced CT were observed in 70.5% of the irradiated parotids. Low-density changes due to fat degeneration were seen in 46.2% and 72.2% of the irradiated parotids 2 and 3 years after radiotherapy, respectively. The mean dose applied to the parotids with the low-density changes and without such changes 3 years after radiotherapy was 46.0 Gy and 27.7 Gy, respectively (p=0.049). Furthermore, parotid shrinkage was observed in 63.6% of the irradiated parotids. Conclusions: This study suggests that the structural variations in parotid glands induced by radiotherapy included high-density changes that were observed immediately after radiotherapy and low-density changes that were seen at late follow-up. This study should be useful for clinicians in the assessment of radiation-induced injuries in the parotids with respect to early prediction of xerostomia

Importance of absorbable surgical sutures for the prevention of stitch abscess after surgery in patients with oral squamous cell carcinoma

To elucidate the significance of absorbable surgical sutures in the occurrence of stitch abscess after surgery in patients with oral squamous cell carcinoma (SCC). The subjects were 251 patients who underwent excision and/or reconstruction and/or neck dissection for oral SCC using absorbable surgical sutures. Detection rates and characteristics of patients with stitch abscess were retrospectively evaluated by comparing between our present and previous data. There was only one stitch abscess among the 251 patients. A significant difference in the incidence of stitch abscess was found between the present data and our previous data. Of course, no significant correlations were found between the occurrence of stitch abscess using absorbable surgical sutures and the various factors seen in our previous analysis. A complete switch of surgical sutures from silk to absorbable surgical sutures is needed for surgery in patients with oral SCC

Elevated Intraocular Pressure, Optic Nerve Atrophy, and Impaired Retinal Development in ODAG Transgenic Mice

PURPOSE. In an earlier study, a cDNA was cloned that showed abundant expression in the eye at postnatal day (P)2 but was downregulated at P10; it was named ODAG (ocular development-associated gene). Its biological function was examined by generating and analyzing transgenic mice overexpressing ODAG (ODAG Tg) in the eye and by identifying ODAG-binding proteins. METHODS. Transgenic mice were generated by using the mouse Crx promoter. EGFP was designed to be coexpressed with transgenic ODAG, to identify transgene-expressing cells. Overexpression of ODAG was confirmed by Northern and Western blot analysis. IOP was measured with a microneedle technique. The eyes were macroscopically examined and histologically analyzed. EGFP expression was detected by confocal microscope. Proteins associated with ODAG were isolated by pulldown assay in conjugation with mass spectrometry. RESULTS. Macroscopically, ODAG Tg exhibited gradual protrusion of the eyeballs. The mean IOP of ODAG Tg was significantly higher than that of wild-type (WT) littermates. Histologic analysis exhibited optic nerve atrophy and impaired retinal development in the ODAG Tg eye. EGFP was expressed highly in the presumptive outer nuclear layer and weakly in the presumptive inner nuclear layer in the ODAG Tg retina. Rab6-GTPase-activating protein (Rab6-GAP) and its substrate, Rab6, were identified as ODAG-binding proteins. CONCLUSIONS. Deregulated expression of ODAG in the eye induces elevated intraocular pressure and optic nerve atrophy and impairs retinal development, possibly by interfering with the Rab6/Rab6-GAP-mediated signaling pathway. These results provide new insights into the mechanisms regulating ocular development, and ODAG Tg would be a novel animal model for human diseases caused by ocular hypertension. (Invest Ophthalmol Vis Sci. 2009;50:242-248) DOI:10.1167/iovs.08-2206 O cular development is a complex process, involving several genes with expression that is strictly controlled in a spatial and temporal manner. Although several genes, including Pax6, Rx, and Crx, are essential for normal ocular formation, 1-3 the molecular mechanism(s) governing eye development has not been fully elucidated. To identify genes that are preferentially expressed in the developing eye, we performed a differential display using mRNAs extracted from postnatal day (P)2 and P10 mouse eyes. 4 At P2, ODAG was highly expressed in all the retinal layers (presumptive outer nuclear layer [ONL], presumptive inner nuclear layer [INL], and ganglion cell layer [GCL]), but at P7, its expression decreases, especially in the GCL, and at P14, no apparent expression is detected. To investigate, we generated transgenic mice overexpressing ODAG (ODAG Tg). The mouse Crx promoter, which directs transgene expression in photoreceptors, From th

Time-resolved serial femtosecond crystallography reveals early structural changes in channelrhodopsin

X線自由電子レーザーを用いて、光照射によるチャネルロドプシンの構造変化の過程を捉えることに成功. 京都大学プレスリリース. 2021-03-26.Channelrhodopsins (ChRs) are microbial light-gated ion channels utilized in optogenetics to control neural activity with light . Light absorption causes retinal chromophore isomerization and subsequent protein conformational changes visualized as optically distinguished intermediates, coupled with channel opening and closing. However, the detailed molecular events underlying channel gating remain unknown. We performed time-resolved serial femtosecond crystallographic analyses of ChR by using an X-ray free electron laser, which revealed conformational changes following photoactivation. The isomerized retinal adopts a twisted conformation and shifts toward the putative internal proton donor residues, consequently inducing an outward shift of TM3, as well as a local deformation in TM7. These early conformational changes in the pore-forming helices should be the triggers that lead to opening of the ion conducting pore