Takaaki Oda

Evaluation of the Efficacy of a Small CdTe γ-Camera for Sentinel Lymph Node Biopsy

We previously reported the basic performance of a prototype small cadmium telluride (CdTe) γ-camera (SSGC) intended for use in radioguided surgeries. In this study, we sought to confirm the favorable previous results and to extend the preliminary findings to examine the efficacy of the SSGC in an animal study and a clinical setting for sentinel lymph node biopsy. Methods: The prototype SSGC (1,024 pixels; field of view, 44.8 × 44.8 mm), equipped with a parallel-hole collimator, was used in both animal and clinical studies. 99mTc-phytate (18.5 MBq) was injected into the tongues and legs of 6 rabbits. In the clinical study, 74 MBq of 99mTc-phytate was injected into peritumoral regions in 8 patients with oral cancer. The detection of hot nodes by the SSGC was compared with that by a conventional scintillation γ-camera (CGC). Results: The SSGC detected 29 hot nodes in images of 6 rabbits after injection. The number of hot nodes was the same as the number seen in CGC studies, but the CGC required a longer acquisition time to produce comparable images. There were no differences between the SSGC and the CGC in terms of activity ratios and hot node-to-background ratios. The biodistribution of 99mTc-phytate in removed tissues was evaluated by contact radiography, and radioactivity was assayed with a γ-well counter. The mean ± SD radioactivity in specimens was 0.15% ± 0.15%, with a range of 0.01%–0.62%. In the clinical study, the SSGC detected 30 hot nodes with a 5- to 60-s acquisition time at 4 h after injection. The SSGC documented all hot nodes depicted by the CGC at 4 h after injection. Conclusion: The SSGC showed significant potential for the detection of sentinel lymph nodes in lymphoscintigraphy. The results of the studies suggested that the SSGC facilitates the exploration of hot nodes in sentinel lymph node biopsy.

Evaluation by Bone Scintigraphy of Osteogenic Activity of Commercial Bioceramics (Porous β-TCP and HAp Particles) Subcutaneously Implanted in Rats:

Osteogenic potential of biomaterials used in bone regenerative therapy has been mainly examined in an animal-implantation study. We have here evaluated the applicability of bone scintigraphy in imaging ectopic bone formation, especially its initial phase, by β-tricalcium phosphate (β-TCP) particles that were implanted in rat dorsal subcutaneous tissues. In implanted osteogenic osteosarcoma cells used as a positive control, osteoid formation was found by histological examination and bone scintigraphy using 99mTc- hydroxymethyl diphosphonate (HMDP) at 2 and 3 weeks post-implantation, respectively, while the microfocuscomputed tomography (μCT) system required further mineralization, which occurred at 4 weeks. Implantation of β-TCP particles alone induced only faint biomineralization inside the particles, which could be microscopically detected by calcein chelation at 2 weeks post-implantation, but not by other histological examinations (e.g., HE staining) or μCT. However, the bone scintigraphy successfully detected this microscopic change at 1 week. Implanted hydroxyapatite (HAp) particles alone used as a negative control did not induce mineralization at microscopic levels, and therefore nothing was detected by either calcein chelation or bone scintigraphy. In conclusion, the bone scintigraphic methodology, although exhibiting less quantitation and resolution, would be applicable as a non-invasive, highly sensitive methodology in detecting the initial, microscopic changes associated with mineralization.

Magnetic resonance imaging findings of nodular fasciitis in the mental region.

Nodular fasciitis (NF) is a benign reactive lesion of the soft tissues related to the fascia and characterized by fibroblastic proliferation. The most common site is the upper extremities (46%), followed by the head and neck region (20%). In the orofacial region, the lesion typically develops within the subcutaneous structures overlying the angle and inferior border of the mandible and the zygoma. Magnetic resonance imaging (MRI) findings of NF in the orofacial region are almost unreported in the literature. In the present case report, we describe MRI findings of mental NF in a 19-year-old woman. MRI revealed a well-defined, round soft-tissue mass lying on the mentum. On T1-weighted MRI, the lesion was isointense to skeletal muscle; it was hyperintense to skeletal muscle on T2-weighted MRI, and was enhanced by Gd-diethylenetriamine pentaacetic acid (DTPA). Histologic examination revealed abundant myxoid degeneration dispersed in the lesion. The T2-weighted higher heterogeneous signal intensity was likely due to abundant myxoid degeneration or the cellular component of the lesion. A strong bright signal intensity belt appeared in the periphery of the lesion on Gd-DTPA enhancement. This rim enhancement appearred to represent small arterioles and venules that were visible in the peripheral area on histologic examination.

Changes of cerebrospinal fluid in the upper neck area with age using diffusion weighted MR imaging

Purpose: Few studies have concerned the absolute apparent diffusion coefficient (ADC) values in the normal cerebrospinal fluid in the upper neck area and the effect of aging on diffusion. The purpose of this study was to evaluate changes of cerebrospinal fluid in the upper neck area with age using diffusion weighted MR imaging (DWI). Methods and methods: Our study included 160 patients who underwent MR imaging for oral and maxillofacial diseases. All patients were examined by DWI with 2 b values (0 and 800 sec/mm 2 ) at 1.5 Tesla and ADC maps. The cerebrospinal fluid and spinal cord in the upper neck area were analyzed using the ADC values and age. Results: ADC value of cerebrospinal fluid was significantly correlated to ADC value of spinal cord ( R 2 = 0.141, p = .000). ADC value of spinal cord had no relation to age ( R 2 = 0.015, p = .125). ADC value of cerebrospinal fluid had significant relation to age ( R 2 = 0.026, p = .042). Conclusions: We indicated the changes of cerebrospinal fluid in the upper neck area with age using DWI. The data reported herein are representative, and the ADC values can be used for reference in future studies and in clinical settings.

Usefulness of shear wave elastography in the diagnosis of oral and maxillofacial diseases

Purpose To evaluate the usefulness of shear wave elastography in the diagnosis of oral and maxillofacial diseases. Materials and Methods Ten patients with oral and maxillofacial diseases and 28 volunteers drawn from our student doctors were examined by shear wave elastography with a 14-MHz linear transducer using an Aplio 300 apparatus (Canon Medical Systems, Otawara, Japan). A statistical analysis of the shear elastic modulus (kPa) of healthy tissue (the sublingual gland, submandibular gland, anterior belly of the digastric muscle, and geniohyoid muscle) in the 28 volunteers was performed using 1-way repeated measures analysis of variance with the Tukey honest significant difference test. The maximum shear elastic modulus (kPa) of 8 patients with squamous cell carcinoma (SCC) and 2 patients with benign lesions was evaluated with the Mann-Whitney U test. The analysis used a 5% significance level. Results The mean shear elastic modulus of the sublingual gland (9.4±3.7 kPa) was lower than that of the geniohyoid muscle (19.2±9.2 kPa, P=.000) and the anterior belly of the digastric muscle (15.3±6.1 kPa, P=.004). The maximum shear elastic modulus of the SCCs (109.6±14.4 kPa) was higher than that of the benign lesions (46.4±26.8 kPa, P=.044). Conclusion Our results demonstrated the usefulness of shear wave elastography in the diagnosis of oral and maxillofacial diseases. Shear wave elastography has the potential to be an effective technique for the objective and quantitative diagnosis of oral and maxillofacial diseases.

Strain elastography of tongue carcinoma using intraoral ultrasonography: A preliminary study to characterize normal tissues and lesions

Purpose The aim of this study was to evaluate the quantitative strain elastography of tongue carcinoma using intraoral ultrasonography. Materials and Methods Two patients with squamous cell carcinoma (SCC) who underwent quantitative strain elastography for the diagnosis of tongue lesions using intraoral ultrasonography were included in this prospective study. Strain elastography was performed using a linear 14 MHz transducer (Aplio 300; Canon Medical Systems, Otawara, Japan). Manual light compression and decompression of the tongue by the transducer was performed to achieve optimal and consistent color coding. The variation in tissue strain over time caused by the compression exerted using the probe was displayed as a strain graph. The integrated strain elastography software allowed the operator to place circular regions of interest (ROIs) of various diameters within the elastography window, and automatically displayed quantitative strain (%) for each ROI. Quantitative indices of the strain (%) were measured for normal tissues and lesions in the tongue. Results The average strain of normal tissue and tongue SCC in a 50-year-old man was 1.468% and 0.000%, respectively. The average strain of normal tissue and tongue SCC in a 59-year-old man was 1.007% and 0.000%, respectively. Conclusion We investigated the quantitative strain elastography of tongue carcinoma using intraoral ultrasonography. Strain elastography using intraoral ultrasonography is a promising technique for characterizing and differentiating normal tissues and SCC in the tongue.

Structural Variations in Parotid Glands Induced by Radiation Therapy in Patients with Oral Carcinoma Observed on Contrast-Enhanced Computed Tomography

Summary 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.

Characteristic Multimodal Imaging of Medication- Related Osteonecrosis of the Jaw: Comparison Between Oral and Parenteral Routes of Medication Administration

Summary 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 χ2 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.

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

Summary 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.

Extraosseous plasmacytoma of the Maxilla: CT and MRI findings

Abstract Plasmacytomas are a localized proliferation of plasma cells in the bone marrow and are less frequently seen in extraosseous organs or tissues. Extraosseous plasmacytoma is a rare malignant neoplasm and constitutes 3–5% of all plasma cell neoplasms. In this article, we describe a case of a patient with extraosseous plasmacytoma of the maxilla and the related computed tomography (CT) and magnetic resonance imaging (MRI) findings.