Masakazu Gotoh

Bifid Mandibular Canal in Japanese

The location and configuration of mandibular canal variations are important in surgical procedures involving the mandible, such as extraction of an impacted third molar, dental implant treatment, and sagittal split ramus osteotomy. We report 3 Japanese patients with bifid mandibular canals using panoramic radiograph and multi-slice helical computed tomography (CT) images. In 2 of the 5 sides, the bifid mandibular canal was suggested on panoramic radiograph. The bifid mandibular canal had a short and narrow upper canal toward the distal area of the second molar in 4 sides, and a short and narrow lower canal toward the distal area of second molar in 1 side, as revealed on reconstructed CT images. Since the location and configuration of mandibular canal variations are important in surgical procedures involving the mandible, they should be carefully observed using reconstructed CT images.

Magnetic resonance imaging assessment of tumorous lesions in the floor of the mouth: case reports and review of the literature

ObjectivesMagnetic resonance (MR) imaging may provide some information as to the extent and tissue characteristics of a cancerous mass, but the imaging features of lesions in the floor of the mouth have not been sufficiently clarified. MR imaging features of tumescent lesions in this region were characterized, and the differential diagnoses are discussed.MethodsMR images of 12 patients with tumescent lesions in the floor of the mouth (three patients with squamous cell carcinoma, two with adenoid cystic carcinoma, one with hemangioma, one with schwannoma, one with lipoma, and four with ranula) were reviewed. The literature on the imaging features of tumescent disease in the floor of the mouth was searched using the Medline database.ResultsSix types of tumescent lesions in the floor of the mouth are presented. The differential diagnosis through a review of the references is discussed. Malignant tumors were demonstrated as ill-defined masses. MR images were good at showing the internal structures, such as fluid, hemorrhage, fat, nerves, calculus (phlebolith), cholesterol, and keratin, as different signal intensities. Therefore, MR images gave clues for the differential diagnosis.ConclusionMR images presented the distinctive features or the extent of the lesions and were therefore considered useful for a more accurate diagnosis prior to treatment.

Computed tomographic anatomy of the mandibular first and second molars and their surrounding structures in the spread of odontogenic infection

ObjectivesThe purposes of this study were to analyze the CT anatomy of the mandibular first and second molars in uninfected subjects and to clarify the pathway of odontogenic infection originating from the mandibular first and second molars.MethodsCT anatomies, especially for bucco-lingual aspects and the surrounding soft tissues, were investigated in 100 uninfected subjects and 17 infected patients.ResultsAt the level of bifurcation, disappearance of the cortical plates was frequently observed on the buccal and lingual sides of the first molars, and it was reduced on the buccal side in the second molar. In the first molar, the bony width was thinner on the buccal than the lingual side. The lingual cortices were thinner in the second molar. All medial pterygoid and 88% of masseter muscles were situated posteriorly, without horizontally overlapping the second molar, whereas the mylohyoid muscle (MhM) overlapped horizontally with the first and second molars. The MhM was positioned superior to the root apices in 10 and 39% of first and second molars, respectively. All patients with first molar infection showed involvement of buccal structures, and one showed lingual side involvement. In contrast, six of nine patients with second molar infection showed involvement on the lingual side.ConclusionsInfection originating from the second molar was more likely to spread to the lingual side than infection originating from the first molar. CT anatomy surrounding the causal teeth supported the spread pathways of mandibular first and second molar infection.

Imaging features of acinic cell carcinoma: three case reports and a review of the literature

ObjectivesThe purpose of this study was to investigate the imaging characteristics of acinic cell carcinoma in three patients and to present a review of the relevant literature.MethodsThe tumor site, shape, size, boundary, internal homogeneity and density, and appearance of contrast enhancement were evaluated in three patients with histologically proven acinic cell carcinoma using computed tomography (CT), magnetic resonance (MR), or ultrasonography (US) images. Through a review of the literature, imaging features are summarized.ResultsAcinic cell carcinoma frequently occurred in the parotid gland. The shape and size were various. The tumor was well-circumscribed and homogeneous if there was no cyst, hemorrhage, or calcification within the tumor. Most lesions showed low and high signal intensities on T1 and T2-weighted MR images, respectively. The tumor was slightly or peripherally enhanced by the contrast medium.ConclusionsAcinic cell carcinoma has often been described as a well-circumscribed and homogeneous mass. Even if the tumor in the parotid gland shows benign features on imaging, we should consider acinic cell carcinoma as part of the differential diagnosis.

Computer-based videofluorographic analysis of posterior pharyngeal wall movement during swallowing in patients with head-and-neck cancer

ObjectivesWe sought to develop a method for evaluating dysphagia using videofluorography (VF) by analyzing the time course of changes in pharyngeal wall movement and to assess patients with head-and-neck cancer before and after surgery.MethodsThe subjects were 14 patients diagnosed with head-and-neck cancer. We obtained VF images before and after surgery and analyzed them with two-dimensional video measurement software. Then, we calculated dysfunction scores based on the remaining or aspiration amount of sample by interpreting the VF images.ResultsWe found dysmotility of the posterior pharyngeal wall in some postoperative cases. Inter- and intrarater reproducibility was high in the evaluation of posterior pharyngeal wall movements. A significant difference was found in the scores between the patients showing dysmotility of the posterior pharyngeal wall and no dysmotility.ConclusionsWe developed a reproducible method for evaluating movements of the posterior pharyngeal wall during swallowing using VF. This may become a useful tool for objectively evaluating VF data.

Ultrasonographic Evaluation and Differentiation of Tumorous Lesions in the Floor of the Mouth: Case Reports and a Review of the Literature

Abstract Ultrasonography may provide some information as to the tissue characteristics of tumorous lesions in the floor of the mouth, which have not been sufficiently clarified. Ultrasonographic imaging characteristics of these lesions are presented and the differential diagnoses are discussed. Ultrasonographic images of 5 patients with metastatic lingual lymph nodes (squamous cell carcinoma), lymphangioma, Schwannoma, ranula and dermoid cyst are presented. The literature on the imaging features of tumorous lesions in the floor of the mouth was searched using Medline. Five cases of tumorous lesions in the floor of the mouth are presented. The differential diagnosis through a review of the references was discussed. Ultrasonographic images clearly showed the internal structures of the mass. The homogeneity varied according to the degree of closeness of the cells and tissues, or the presence of fluid, hemorrhage, cystic degeneration and calculus. The echogenicity was due to the high acoustic impedance of calculus, cholesterol, so on. The imaging features varied according to the ratio of the tissues, such as fat and fibrous tissue (in lipoma), or cholesterol and keratin (in dermoid cyst). A high vascular mass indicated malignant salivary gland tumors and hemangioma. In conclusion, ultrasonographic images revealed the distinctive features of the lesions and were useful for the differential diagnosis. Therefore, ultrasonography could be used to conjecture the content of the lesions and is considered to be useful for easy and accurate diagnosis prior to treatment.

Computed Tomographic Analysis of Inflammatory Spread in Adult Parotitis

Abstract Adult parotitis exhibits various appearances on images. The purpose of this study was to investigate the imaging features of adult parotitis, focusing on the inflammatory spread in and around the parotid gland on CT images. We investigated 21 patients who were clinically and radiologically diagnosed with parotitis, including patients with concomitant occurrences of sialolith or Sjogrens syndrome. Intra-glandular spread was divided into 13 diffuse types and 8 focal types. There was a significant difference in duration from the first onset of symptoms between the diffuse and focal types. Six of 8 patients showing focal type spread were associated with the concomitant occurrence of sialolith or Sjogrens syndrome. Extra-glandular spread was observed in 13 (6%) patients. Of them, 12 (92%) showed subcutaneous fat tissue and/or masticator space involvement. Involvement of the parapharyngeal space and the superficial area just below the gland was observed in 4 and 7 patients, respectively. The appearance of extra-glandular spread was influenced by intra-glandular appearance and concomitant disease. The spread of adult parotitis possessed characteristic features in relation to clinical findings and concomitant disease. CT examination appeared to be effective for these diagnoses.