Ikuho Kojima

Diagnostic value of capsule-like rim enhancement on magnetic resonance imaging for distinguishing malignant from benign parotid tumours

The purpose of this study was to clarify the diagnostic value of capsule-like rim enhancement (CLRE) on magnetic resonance imaging (MRI) for distinguishing malignant from benign tumours of the parotid gland. We retrospectively evaluated contrast-enhanced T1-weighted images of 100 patients with malignant and benign parotid tumours for the presence, completeness, and irregularity of CLRE and its maximum thickness. We investigated any correlation of imaging and histopathological findings for 51 cases showing CLRE with available histology. The presence and completeness of CLRE did not differ significantly between benign and malignant tumours. Malignant tumours had more irregular CLRE than benign tumours (P<0.05). The mean CLRE thickness was significantly greater for malignant (2.4 mm) than benign tumours (1.4 mm) (P<0.0001). The two types of tumour were most accurately distinguished using a cut-off value of 1.5 mm thickness. Histopathology demonstrated the general correspondence of thick CLRE on MRI in malignant tumours with thick but sparse fibrous tissue and infiltration of tumour cells and lymphocytes, whereas thin CLRE in benign tumours typically represented dense fibrous tissue without infiltration of tumour cells. CLRE was more irregular and thicker in malignant tumours than in benign tumours, which may be of help in differentiating them.

Excessive lateral dental arch expansion in experimentally developed acromegaly-like rats.

OBJECTIVE To investigate morphological changes in the dental arches of acromegaly-like rats recently developed by means of exogenous IGF-I administration. DESIGN Human recombinant IGF-I (640microg/day) was continuously administered subcutaneously for 4 weeks by osmotic mini-pumps to 10-week-old male rats (n=6). Control animals were injected with saline alone (n=6). After administration, all the rats were housed for 4 more weeks. Arch width (W), length (L) and angle (theta) in the mandible and maxilla were measured once a week during and after IGF-I administration. RESULTS The concentration of circulating IGF-I, and W and theta in the mandible were significantly increased as compared with the control rats. Although the mandibular dental arch stopped expanding once administration ended, it did not return to the control size. CONCLUSIONS In our acromegaly-like rat model, mandibular dental arch growth is greater in the lateral than antero-posterior direction during and after IGF-I administration.

High Serum Levels of IGF-I Contribute to Promotion of Endochondral Ossification in Mandibular Condyle and Cause its Specific Elongation in Acromegaly-like Rats

Mandibular protrusion accompanies acromegaly or acrogigantism. To clarify the detailed mechanisms, we used an acromegaly-like rat model recently developed by exogenous administration of insulin-like growth factor I (IGF-I). Human recombinant IGF-I (640 microg/day) continuously was infused subcutaneously to 10-week-old male rats (n=12) for four weeks. Control, sham-operated animals (n=12) were injected with saline alone. Twelve rats (six from each group) were killed immediately after ending administration at age 14 weeks. Another 12 rats (six from each group) were housed for an additional four weeks after treatment ended. Mandibular condylar length increased significantly in the IGF-I rats compared with the control rats, but no significant intergroup difference was found in the lengths of the coronoid and angular processes. Cartilaginous layer width, bone matrix volume, and the number of osteoblasts in the mandibular condyle increased significantly in the IGF-I group. These histopathological changes in the condyle disappeared after IGF-I administration was discontinued; however, the morphological change in condylar length remained. These findings suggest that mandibular protrusion in patients with acromegaly or acrogigantism may be evoked by superfluous elongation of the mandibular condyle and that such elongation can be induced by endochondral ossification caused by high IGF-I serum levels.

Root canal filling materials spread pattern mimicking root fractures in dental CBCT images.

OBJECTIVE To clarify the cause of artificial tooth-root fracture lines in cone beam computed tomography (CBCT) images caused by root canal filling materials and to enhance the diagnostic performance of CBCT. STUDY DESIGN We analyzed the CBCT images of 18 extracted human teeth (9 upper central incisors and 9 lower premolars) that were filled with a size 50 gutta-percha cone and inserted into tooth sockets in a human skull. RESULTS The CBCT images of the incisors displayed artificial lines in the oblique directions, notably the mesiobuccal, distolingual, distobuccal and mesiolingual directions, but only rarely in the cross-directions (buccal, lingual, mesial, and distal). In the premolars, the reverse was true, with lines mainly in the cross-directions, mesial and distal directions particularly. The lines were predominantly at the cervical slice. CONCLUSIONS Artifacts resulting from root filling material appear along the long axis of the alveolar bones, and resemble root fractures.

Diagnostic Performance of MR Imaging of Three Major Salivary Glands for Sjögren's Syndrome

OBJECTIVE We analyzed the diagnostic performance of the MR imaging findings of the parotid, submandibular, and sublingual glands to discriminate between patients with and without Sjögrens syndrome. METHODS We retrospectively analyzed the correlation between the MR imaging and histopathological findings obtained from 69 patients with clinically suspected Sjögrens syndrome. We evaluated the heterogeneous signal intensity distribution on T1- and T2-weighted images, the multiple high-signal-intensity spots on MR sialograms, and the volume of the parotid, submandibular, and sublingual salivary glands. RESULTS The multiple high-signal-intensity spots in the parotid gland showed the highest sensitivity and diagnostic accuracy (82% and 83%, respectively). In addition, the multiple high-signal-intensity spots and the heterogeneous signal intensity distribution in the submandibular gland showed high specificity (100% and 88%, respectively). The volume of the submandibular gland, but not that of the parotid or sublingual gland, was smaller in patients with Sjögrens syndrome. CONCLUSIONS The presence of multiple high-signal-intensity spots on an MR sialogram in the parotid gland should be considered the best diagnostic indicator for Sjögrens syndrome. The presence of spots, heterogeneity, and the change to smaller volumes in the submandibular gland were also helpful because of their high specificity, particularly in advanced cases.

Comorbid masticatory impairment delays recovery from acute cerebral ischemia and locomotor hypoactivity after subarachnoid hemorrhage in mice

Tooth loss and related changes in the functionality may lead to worse outcome of stroke patients, but the effect on hemorrhagic stroke remains unclear. This study aimed to determine the impact of impaired masticatory function on acute cerebral oxygenation and locomotor activity after experimental subarachnoid haemorrhage (SAH). Twenty C57BL/6 mice with (MC‐treated group) or without (control group) prior treatment of cutting off the upper molars were subjected to SAH by endovascular perforation. Grading of SAH and acute cerebral infarction were assessed by MR images. Brain tissue oxygen saturation (SbtO2) by photoacoustic imaging and parameters related to locomotor activity by open‐field test were analyzed serially after SAH. In all mice, global SbtO2 depression was notable immediately after SAH induction (P <.001), which recovered close to the baseline levels until day 3. However, MC‐treated mice demonstrated a prolonged relative cerebral hypoxia (<40% of the baseline SbtO2) as compared to the control (3 ± 1 vs 1 ± 1 days; P <.05). The average distance travelled on day 7 and the ratio of central‐area distance/total travelled distance by open‐field test between days 7 and 14 were significantly lower in MC‐treated mice than in the control mice (P <.05), although the occurrences of new infarction were not statistically different (P >.05). These data suggest a possible link between preceding masticatory impairment and early brain injury to deteriorate neurobehavioural function in patients after SAH.This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/1440-1681.12874 This article is protected by copyright. All rights reserved. PROF. TATSUSHI MUTOH (Orcid ID : 0000-0001-7770-379X)

MRI-based in vivo assessment of early cerebral infarction in a mouse filament perforation model of subarachnoid hemorrhage

BACKGROUND AND PURPOSE Experimental subarachnoid hemorrhage (SAH) by endovascular filament perforation method is used widely in mice, but it sometimes present acute cerebral infarctions with varied magnitude and anatomical location. This study aimed to determine the prevalence and location of the acute ischemic injury in this experimental model. METHODS Male C57BL/6 mice were subjected to SAH by endovascular perforation. Distribution of SAH was defined by T2*-weighted images within 1h after SAH. Prevalence and location of acute infarction were assessed by diffusion-weighted MR images on day 1 after the induction. RESULTS Among 72 mice successfully acquired post-SAH MR images, 29 (40%) developed acute infarction. Location of the infarcts was classified into either single infarct (ipsilateral cortex, n=12; caudate putamen, n=3; hippocampus, n=1) or multiple lesions (cortex and caudate putamen, n=6; cortex and hippocampus, n=2; cortex, hippocampus and thalamus/hypothalamus, n=3; bilateral cortex, n=2). The mortality rate within 24h was significantly higher in mice with multiple infarcts than those with single lesion (30% versus 0%; P=0.03). Distribution of the ischemic lesion positively correlated with MRI-evidenced SAH grading (r2=0.31, P=0.0002). CONCLUSION Experimental SAH immediately after the vessel perforation can induce acute cerebral infarction in varying vascular territories, resulting in increased mortality. The present model may in part, help researchers to interpret the mechanism of clinically-evidenced early multiple combined infarction.

Insulin-Like Growth Factor I Inhibits Alveolar Bone Loss Following Tooth Extraction in Rats.

BACKGROUND Alveolar bone is often lost after tooth extraction. Few studies have assessed the longitudinal changes in bone volume that occur within these extraction sites. PURPOSE To investigate the longitudinal morphological changes in extraction sockets following sustained continuous subcutaneous infusion of human recombinant insulin-like growth factor I (IGF-I). MATERIALS AND METHODS Fourteen rats were subjected to right mandibular first molar extraction. Experimental rats (n = 7) received a continuous subcutaneous infusion of human recombinant IGF-I (320 mg/day) for 3 weeks by osmotic minipump. Control animals were treated with saline via the same method (n = 7). All rats were then housed for an additional 3 weeks. Micro-CT scanning was performed immediately after tooth extraction and at 1, 2, 3, and 6 weeks after extraction. RESULTS New bone formation was markedly higher in the IGF-I-treated group as compared with the control group. The loss in alveolar ridge height in the IGF-I group was significantly lower than that in the control group at each time point after extraction on the buccal side and at 2, 3, and 6 weeks on the lingual side. CONCLUSIONS IGF-I treatment increases the volume of newly formed bone and reduces the loss in alveolar ridge height following tooth extraction.

Difficulty of the differential diagnosis of basal cell adenoma and basal cell adenocarcinoma of parotid gland by magnetic resonance imaging: case reports and literature review

ObjectivesThe aim of this study was to assess the efficacy of magnetic resonance imaging (MRI) for the differential diagnosis of basal cell adenocarcinoma (BCAC) and basal cell adenoma (BCA) in the salivary gland.MethodsMagnetic resonance imaging findings and pathological correlations were studied retrospectively in three cases of pathologically verified BCA and one case of BCAC. The MRI findings from previously reported cases (16 cases of BCA, 1 case of BCAC) were reviewed.ResultsAll three BCAs showed well-defined margins, a round or ovoid shape, homogeneous hypointense signal on T1-weighted imaging (T1WI), and moderate contrast enhancement on contrast-enhanced T1WI. T2-weighted imaging showed heterogeneous hyperintense signals in two cases and a hypointense signal in one. The BCAC displayed MRI findings similar to those of the BCAs, with histopathologically verified partial invasion into the surrounding tissue remaining undetected. Time-signal intensity curves on dynamic MRI displayed rapid enhancement followed by a low washout pattern in all BCA cases, and a gradual enhancement pattern in the BCAC case. Both of these patterns are nonspecific and are commonly seen in other salivary tumors.ConclusionsBoth the BCAs and the BCAC showed nonspecific findings on MRI, making it difficult to distinguish between these entities, even with dynamic MRI.

Morphological and Histopathological Changes in Orofacial Structures of Experimentally Developed Acromegaly-Like Rats: An Overview

Tongue enlargement and mandibular prognathism are clinically recognized in almost all patients with acromegaly. An acromegaly-like rat model recently developed by exogenous administration of insulin-like growth factor I (IGF-I) was used to investigate morphological and histopathological changes in orofacial structures and to clarify whether these changes were reversible. Exogenous administration of IGF-I evoked specific enlargement of the tongue with identifiable histopathological changes (increased muscle bundle width, increased space between muscle bundles, and increased epithelial thickness), elongation of the mandibular alveolar bone and ascending ramus, and lateral expansion of the mandibular dental arch. Regarding histopathological changes in the mandibular condyle, the cartilaginous layer width, bone matrix ratio, and number of osteoblasts were all significantly greater in this rat model. After normalization of the circulating IGF-I level, tongue enlargement and histopathological changes in the tongue and mandibular condyle were reversible, whereas morphological skeletal changes in the mandible remained.