Assessment of MRI and dynamic contrast-enhanced MRI in the differential diagnosis of adenomatoid odontogenic tumor.

The radiographical differentiation of adenomatoid odontogenic tumor (AOT) from dentigerous cysts, calcifying odontogenic cysts, calcifying epithelial odontogenic tumors, odontogenic keratocysts and amelobastomas is sometimes difficult. We attempted to differentiate AOT from other lesions similar to AOT in radiographic findings using MRI. The MRI features of AOT in our three cases included homogeneous low SI in the cystic portion and homogeneous intermediate SI in the solid portion on T1WI, homogeneous high SI in the cystic portion and intermediate to slightly high SI in the solid portion on T2WI and enhancement of only the solid portion on CE-T1WI although none of the sequences included SI of calcifications. The contrast index curves in the three cases of AOT showed a gradual increase to 300 s, which signified a benign tumor. These MRI features were characteristic features of AOT and might be a basis for differentiating AOT from the above possible lesions in radiographic examinations.

MR imaging of epithelial cysts of the oral and maxillofacial region.

The aim of the present study was to review the magnetic resonance (MR) appearance of primary epithelial cysts in order to distinguish the cysts from other possible lesions. MR images were obtained in 27 cases of epithelial cysts, including 7 odontogenic keratocysts, 3 dentigerous cysts, 1 glandular odontogenic cyst, 10 radicular cysts, 4 nasopalatine duct cysts, and 2 nasolabial cysts. In addition, contrast enhanced MR imagings were performed in 12 cases, including 3 odontogenic keratocysts, 1 dentigerous cyst, 1 glandular odontogenic cyst, and 7 radicular cysts. We obtained the following results on the basis of the above MR and contrast enhanced MR findings. (a) Odontogenic keratocysts had a predilection for intermediate-high signal intensity (SI) on T1-weighted images (WI) and heterogeneous low-high SI on T2WI. (b) Dentigerous cysts, glandular odontogenic cyst, radicular cysts and nasolabial cysts showed the same predilection with the SI, which were homogeneous intermediate SI on T1WI and homogeneous high SI on T2WI. (c) The MR images of the nasopalatine duct cysts, which showed homogeneous high SI on T1WI, were specific. (d) The Gd-T1WI would be useful in decisively differentiating odontogenic cysts, which showed rim-enhancement, from tumors consisting of solid components. In conclusion, we were able to obtain more information from the MR and contrast enhanced MR images than from conventional radiograph findings.

Effects of p53 gene therapy in radiotherapy or thermotherapy of human head and neck squamous cell carcinoma cell lines.

We report herein the effects of p53 gene therapy in the radiotherapy or thermotherapy of eight human head and neck squamous cell carcinoma (SCC) cell lines. The discrepancy between radiosensitivity combined with p53 gene therapy than that without p53 gene therapy increased among the eight SCC cell lines. The discrepancy increased in the thermosensitivity at 43 degrees C and decreased in that at 44 degrees C among the eight SCC cell lines. Thus, the p53 gene therapy did not always improve the discrepancy between radiosensitivity and thermosensitivity in the eight SCC cell lines. In the radiotherapy combined with adenoviral p53 gene therapy, the survival rates of three of eight SCC cell lines decreased, and that of only one cell line increased compared with radiotherapy alone. In thermotherapy combined with p53 gene therapy, the survival rates of three at 44 degrees C and five at 43 degrees C of the eight SCC cell lines decreased, although only one cell line at 43 degrees C increased its survival rate compared with thermotherapy alone. The p53 gene therapy decreased the survival rates of both radiotherapy and thermotherapy in three of eight SCC cell lines. Further, the distribution of plots on the basis of the time for 10% survival of radiotherapy and the dose for 10% survival of thermotherapy with p53 gene therapy shifted to the lower left side of the plots compared with those without p53 gene therapy. These findings indicated that p53 gene therapy improves the effects of both radiotherapy and thermotherapy.

Evaluation of tumor proliferation using dynamic contrast enhanced-MRI of oral cavity and oropharyngeal squamous cell carcinoma.

We investigated the relationship between the enhanced patterns acquired by dynamic MRI and the tumor cell proliferation estimated by immunostaining proliferating cell nuclear antigen (PCNA) in oral squamous cell carcinoma (SCC). Thirty patients with primary oral SCC underwent dynamic contrast enhanced (DCE)-MRI using a three-dimensional fast imaging with steady-state precession sequence. Tumor cell proliferation of all surgical specimens was evaluated using immunohistochemical staining with the anti-PCNA antibody. The relationship between the dynamic MRI parameters (maximum CI and maximum CI gain) and the PCNA labeling index was statistically analyzed using regression analysis. The time contrast index curves of all cases showed a rapid and high uptake pattern. The PCNA labeling index showed a significant correlation with maximum CI and maximum CI gain (P<0.0001, r=0.866 and P=0.0019, r=0.544, respectively). The assessment of DCE-MRI parameters may provide valuable information for tumor cell proliferation of the patients with oral cancer.

Thermoradiotherapy combined with adenoviral p53 gene therapy in head and neck squamous cell carcinoma cell lines.

We examined effects of recombinant p53-expressing adenovirus combined with thermoradiotherapy in 8 head and neck squamous cell carcinoma (SCC) cell lines to improve the outcomes of the treatment of advanced head and neck cancer. The p53 gene therapy did not improve the discrepancy between thermoradiosensitivities among the 8 SCC cell lines. However, p53 gene therapy improved the effects of thermoradiotherapy in all 8 cell lines, and there were significant differences in four situations of the HSC4 44 degrees C (p=0.032), SAS at 44 degrees C (p=0.029), the KB at 43 degrees C (p=0.025), and the Ca9-22 43 degrees C (p=0.020). In comparing the survival rates of thermoradiotherapy with those of thermotherapy and radiotherapy, thermoradiotherapy demonstrated actual survival rates less than theoretical survival rates based on the survival rates of thermotherapy multiplied by the survival rates of radiotherapy in almost all treatments of thermoradio-gene therapy of the 8 SCC cell lines. These results demonstrate that thermoradiotherapy combined with p53 gene therapy may be a useful tool in treating SCC cells.

MR features of aneurysmal bone cyst of the mandible and characteristics distinguishing it from other lesions.

Aneurysmal bone cyst (ABC) is a relatively rare, non-neoplastic expansile lesion of bone. Bleeding may occur during an operation or biopsy for ABC, as this cyst is an aneurys with numerous pools of blood. Therefore, it is necessary to diagnose ABC before treatment or biopsy. In the present report, we describe the characteristic computed tomography (CT) and magnetic resonance imaging (MRI) features of ABC in the mandible. Based on the literature and on our own experiences, we compare with the features of ABC with the corresponding features of other lesions showing similar conventional radiographic appearances. In the present case, bone-targeting CT showed the characteristic feature, which reflected the histopathological appearance of a partially cystic meshwork divided by coarse septa. MRI showed almost homogeneous intermediate signal intensity, including a partial slight low-signal-intensity area on the T1-weighted image, and homogeneous high signal intensity, which showed a 'bubbly' appearance, on T2-weighted image. On the enhanced T1-weighted image, the intermediate signal intensity areas apart from the areas that showed slight low-signal intensity on the non-enhanced T1-weighted image, were well enhanced. This creates a 'honeycomb' appearance. The 'meshwork' appearance on bone-targeting CT, the 'bubbly' appearance on the T2WI and the 'honeycomb' appearance on Gd-T1WI may be the characteristic features of ABC.

Thermoradiotherapy combined with p53 gene therapy of human salivary gland adenocarcinoma cell line.

We report on thermoradiotherapy combined with p53 gene therapy in the human salivary gland adenocarcinoma cell line HSG. HSG cells were successfully infected at a rate of 62.3% with MOIs of 20 of either AxCAip53 or AxCAiLacZ. The AxCAiLacZ did not inhibit the survival of the HSG cells. The survival fractions of AxCAip53-infected HSG cells were lower than those of the AxCAiLacZ-infected HSG cells, but there was no significant difference (p=0.30). AxCAip53 decreased the survival rates of thermotherapy (43 degrees C; p=0.084 and 44 degrees C; p=0.18), radiotherapy (6 Gy; p=0.20) and thermoradiotherapy (6 Gy plus 43 degrees C; p=0.24 and 6 Gy plus 44 degrees C; p=0.96), but there were no significant differences. In comparing the survival rates of thermoradiotherapy with those of thermotherapy and radiotherapy, thermoradiotherapy, regardless of the combination with p53 gene therapy, demonstrated actual survival rates lower than theoretical survival rates based on survival rates of thermotherapy multiplied by survival rates of radiotherapy. This result indicates that thermoradiotherapy is effective in the treatment of HSG cells. Thermoradiotherapy combined with p53 gene therapy was the most effective therapy among the combinations of therapies demonstrating that thermoradiotherapy combined with p53 gene therapy may be a useful tool in the treatment of HSG cells.

Adenoviral p53 gene therapy in head and neck squamous cell carcinoma cell lines.

We reconstructed the recombinant p53-expressing adenovirus and examined its infections and effects in head and neck squamous cell carcinoma cell lines. Eight human head and neck squamous cell carcinoma cell lines were infected by the recombinant adenovirus harboring the lacZ gene (AxCAiLacZ) or the wild-type p53 gene (AxCAip53), and the effects were investigated. The eight cell lines were successfully infected by AxCAiLacZ at a level of more than 50%. The survival of all 8 squamous cell lines were inhibited in the range from 8 to 26.7% by only one treatment of the AxCAip53 infection. This result suggested that p53 gene therapy might become a useful tool in head and neck squamous cell carcinoma treatment.

Assessment of carcinoma in the sublingual region based on magnetic resonance imaging.

In the present study, we attempted to diagnose and detect the extent of tumors in the sublingual region using magnetic resonance imaging (MRI) and dynamic MRI. MRI with or without gadopentetate dimeglumine (Gd-DTPA)-enhancement in seven lesions of the sublingual regions was performed. The seven lesions included four cases of mucoepidermoid carcinoma (mucoepidermoid Ca), two cases of adenoid cystic carcinoma (ACC), and one case of squamous cell carcinoma (SCC). Whether the tumor was malignant or benign, as well as the differential diagnosis, could not be determined on the basis of the MR signals, even when enhancement was performed. Dynamic MRI was performed in five cases, two cases of ACC, two cases of mucoepidermoid Ca, and one case of SCC. The dynamic MRI showed a rapid enhancement at 30-45 sec in all five cases before the normal sublingual gland began to be enhanced. The early phases at 30-45 sec of the dynamic MRI in five cases showed marked enhancement before the normal sublingual glands were enhanced, and therefore could clearly show the extent of the lesions. In conclusion, the dynamic MRI may be useful in differentiating malignant from benign tumors, and in detecting the extent of the tumors in the sublingual carcinomas.

Thermoradiotherapy in human head and neck squamous cell carcinoma cell lines.

Thermoradiosensitivity of 8 cell lines of head and neck squamous cell carcinoma (HO-1-u-1, HSC2, HSC3, HSC4, SAS, KB, Hep2, and Ca9-22) was investigated. The differences of radiosensitivity between the cell line with the highest radiosensitivity and the cell line with the lowest radiosensitivity were 1.7-, 7.7-, and 41-fold at 2, 6 and 8 Gy, respectively. The differences between the cell line with the highest thermosensitivity and the cell line with the lowest thermosensitivity were 2.4-, 6.2- and 34.4-fold at 43 degrees C for 40, 60 and 100 min, and 2.6-, 4.9- and 127-fold at 44 degrees C for 20, 30 and 50 min, respectively. These findings indicated that there were large differences in both radiosensitivity and thermosensitivity among the 8 cell lines. There was a negative relationship between radiosensitivity and thermosensitivity (43 degrees C: r=-0.600, 44 degrees C: r=-0.848) in 7 of 8 cell lines, the exception being the HSC4 cell line, which was resistant to both therapies. Four of the 8 cell lines at 43 degrees C and 5 at 44 degrees C in the radiotherapy combined with thermotherapy showed actual survival rates smaller than the theoretical survival rates. Thus, thermoradiotherapy was deemed effective in the head and neck carcinoma cell lines, although 1 of 8 cell lines was resistant to both radiotherapy and thermotherapy.

Application of dynamic MRI to differentiating odontogenic myxomas from ameloblastomas.

It is often difficult to radiographically distinguish odontogenic myxomas from ameloblastomas. In the present study, we tried to differentiate odontogenic myxomas from ameloblastomas using dynamic magnetic resonance imaging (dynamic MRI). Two cases of ameloblastoma with cystic components and two cases of odontogenic myxoma were compared by dynamic MRI. The dynamic MRI features of solid areas of ameloblastomas showed a rapid enhancement, reaching maximum contrast at 45-60 s, and maintained these enhancement levels or showed a gradual wash-out to 600 s thereafter; in contrast, those of the cystic areas of ameloblastomas showed no enhancement. The dynamic MRI features of the whole area of odontogenic myxomas (we considered the whole area to be the tumor substance in the odontogenic myxomas, as based on histopathological examinations) showed a gradual increase in enhancement at 500-600 s. The central portions of the odontogenic myxomas, which did not appear to be enhanced on Gd-T1 weighted images also showed a gradual increase in enhancement at 500-600 s, though the increase was minimal. These results indicate that the dynamic MRI features of odontogenic myxomas are different from those of ameloblastomas. Therefore, dynamic MRI may be a useful tool for diagnosis of myxoma.

Clinical applications of 3-D CT and 3-D plastic models in the maxillo-facial region / Aplicação clínica dos modelos CT 3-D e 3-D plastico na região maxilofacial

We compared the usefulness of 3-D plastic models with that of 3-D CT images with regard to their applications in the field of maxillo-facial medicine. We also considered possibilities for wider clinical applications for both these methods. Five patients with the following conditions were involved in this study: hyperplasia of the mandibular condyle, 1; fracture of the maxilla and mandible, 1; coronoid hyperplasia, 2; and unilateral temporomandibular joint ankylosis with microgenia, 1) Stereolithographic models and 3-D CT images were made for each patient. Ct and 3-D CT images were superior to plastic models with respect to their clinical diagnostic value. Furthermore they provided more precise information about the surface and inner structures of the jaws. 3-D plastic models made it possible to do close observation of the complex anatomical relationship of the region which were easily overlooked on axial CT images and even on 3-D CT images. The 3-D plastic models were useful for simulated surgery in all these cases. In the cases with bilateral coronold process hyperplasia, the plastic model well clarified the direct functional cause of the patients trismus. The analysis on plastic models suggested that the abnormal contact of the coronold process with the deformed surrounding anatomical structures might cause trismus and elongation of the process. We believe that plastic models can be applied to other dental fields such as dental implantology, prosthodontics and measuring for 3-D cephalometry