MRI characteristics of rheumatoid arthritis in the temporomandibular joint.

OBJECTIVES: The aim of this study was to investigate characteristic MRI findings of rheumatoid arthritis (RA) in the temporomandibular joints (TMJs). METHODS: 61 patients (122 TMJs) with RA in the TMJ and 50 patients (100 TMJs) with temporomandibular disorder (TMD) were included in this study. MR images of these patients were assessed by two oral radiologists for the presence or absence of osseous changes, disc displacement, joint effusion and synovial proliferation. These findings were compared between the two patient groups. RESULTS: Osseous changes in the condyle and articular eminence/fossa in the RA patient group were significantly more frequent than in the TMD patient group, and were often very severe. Joint effusion was also significantly more frequent in the RA patient group. Synovial proliferation was found in all TMJs in the RA patient group, whereas it was very uncommon in the TMD patient group. CONCLUSIONS: Severe osseous changes in the condyle and synovial proliferation were considered characteristic MRI findings of RA in the TMJs.

A clinicoradiological study of odontogenic carcinomas and their impact on clinical diagnosis.

OBJECTIVES: To investigate the clinical and radiological characteristics of odontogenic carcinomas (OCs) and evaluate their impact on early clinical diagnosis. METHODS: The clinical and radiological features of all patients with OCs in our pathology record from January 1988 to December 2009 were retrospectively reviewed. The impact on a tentative diagnosis before final histological examination of clinical, panoramic and CT features was investigated. RESULTS: Of 474 cases with malignant jaw tumours, 417 (88%) were gingival squamous cell carcinomas (SCCs) and 27 (6%) were OCs. The average age of the patients with OCs was significantly lower than that of those with gingival SCCs. 20 OCs were in the mandible and 7 were in the maxilla. 22 OC patients (81%) had pain and/or swelling as an initial symptom of the disease. Although the majority of OCs showed irregularly contoured radiolucency, one-third of the cases showed cyst-like radiolucency totally or partially surrounded by a sclerotic rim on panoramic radiography. Permeative or gross cortical bone destruction and mass extension outside the jaw bone were found on CT and a diagnosis of malignant tumour was more common. Mass extension outside the cortex had a significant influence on malignant diagnosis. However, 22% of the patients were still clinically diagnosed as having osteomyelitis after CT. CONCLUSIONS: Although CT was useful to obtain a diagnosis of malignant tumour in OC patients, 22% of patients were clinically diagnosed as having osteomyelitis even after CT. When an osteomyelitis case is resistant to conventional therapy and gross bone destruction and/or mass extension is found on CT, a histopathological examination should be done.

USPIO-enhanced MRI of highly invasive and highly metastasizing transplanted human squamous cell carcinoma: an experimental study.

OBJECTIVE: The aim of this study was to investigate the signal intensity characteristics of highly invasive and highly metastasizing transplanted human squamous cell carcinoma using ultra-small super-paramagnetic iron oxide (USPIO)-enhanced MRI and to correlate them with USPIO distribution to tumour components revealed by histological examination. METHODS: 13 nude mice with transplanted human squamous cell carcinoma in the oral cavity were imaged before and 24 hours after intravenous administration of USPIO. The difference in signal intensity between pre-contrast and post-contrast MR images was visually evaluated. For quantitative analysis, signal intensity within a region of interest was measured. Histological findings were correlated with MR findings. The approximate USPIO concentration was evaluated using USPIO phantoms. RESULTS: Seven tumours had an area showing signal intensity increase on post-contrast T1 weighted images. Histopathologically, six of those tumours contained a small amount of iron particles in the stroma. The USPIO concentration was presumed low. Two tumours had an area showing signal intensity decrease on post-contrast T1 and T2 weighted images. The areas had a large amount of iron particles in the stroma and the USPIO concentration was presumed high. There was a minimal amount of iron particles in tumour parenchymal cells. CONCLUSIONS: The amount of USPIO accumulation into tumour stroma was considered to affect MR signal intensity. A small amount increases T1 weighted signal intensity, whereas a large amount decreases T1 and T2 weighted intensity. The USPIO accumulation into the tumour parenchyma was not thought to affect MR signal intensity.

Diagnostic performance of magnetic resonance imaging for detecting osseous abnormalities of the temporomandibular joint and its correlation with cone beam computed tomography.

OBJECTIVE: With cone beam CT (CBCT) as the reference standard, the objective of this study was to determine the diagnostic accuracy of MRI for assessing osseous abnormalities of the temporomandibular joint (TMJ). METHODS: 106 TMJs from 55 patients with temporomandibular disorder were examined by CBCT and MRI. CBCT images were evaluated by two experienced oral radiologists with regard to the presence or absence of each of the following eight types of osseous abnormalities: Type 1, destructive and erosive osseous changes of the condyle; Type 2, flattening of the articular surface of the condyle; Type 3, deformity of the condyle; Type 4, sclerosis of the condyle; Type 5, osteophyte formation; Type 6, ankylosis; Type 7, erosion of the articular fossa and/or eminence; and Type 8, sclerosis of the articular fossa and/or eminence. For detection of these osseous abnormalities by MRI, proton density-weighted images and T(2) weighted images were evaluated independently by three observers. Using CBCT findings as the reference standard, the diagnostic performance of MRI for detecting various types of osseous abnormalities was evaluated by calculating its sensitivity and specificity. RESULTS: Out of 106 joints, CBCT revealed Types 1, 2, 3, 4, 5, 6, 7 and 8 abnormalities in 25, 19, 26, 20, 14, 5, 19 and 22 joints, respectively. The mean sensitivities of MRI among the three observers for detecting Types 1, 2, 3, 4, 5, 6, 7 and 8 abnormalities were 61%, 30%, 82%, 40%, 48%, 34%, 61% and 41%, respectively, whereas the mean specificities were 86%, 92%, 91%, 95%, 84%, 98%, 89% and 91%, respectively. CONCLUSIONS: Although high specificity (84-98%) was obtained with MRI, this modality showed relatively low sensitivity (30-82%) for detecting osseous abnormalities of the TMJ. The value of MRI for the detection of TMJ osseous abnormalities is considered to be limited.

An investigation of magnetic resonance imaging features in 14 patients with synovial chondromatosis of the temporomandibular joint.

OBJECTIVES: To show the characteristic MRI features of synovial chondromatosis (SC) of the temporomandibular joint (TMJ). METHODS: All patients with histologically proven SC of the TMJ who underwent MRI at our clinic were examined. In 14 patients (male-to-female ratio, 2:12; average age 46+/-14 years), clinical and conventional radiographic findings were reviewed. In addition, the MRI findings of articular disc and condyle position, shape and signal intensity of the joint spaces, and bone changes of surrounding structures were analysed. RESULTS: The main symptoms were pain (in 93% of the patients) and limitation of mouth opening (64%). Two cases showed typical multiple calcifications around the TMJ on conventional radiography. On MRI, the disc position was normal in 12 (86%) patients and the condyle was inferiorly displaced in 9 (64%) patients. 11 (79%) patients showed enlargement of the joint space, with either a "dumbbell" shape or bulging. SC in the upper compartment showed various degrees of bone changes of the articular eminence and fossa. SC in the lower compartment showed concavity or hypertrophy of the condyle. The severity of the bone changes progressed with duration of symptoms. CONCLUSIONS: About 0.3% of the patients complaining of TMJ pain and dysfunction were found to have SC. There was great variation in the MRI features of the TMJs with SC. More severe destruction of surrounding bone structures with features resembling a tumour were found in patients with a longer duration of symptoms.

CT findings as a significant predictive factor for the curability of mandibular osteomyelitis: multivariate analysis.

OBJECTIVES: To re-evaluate computed tomographic (CT) imaging as a diagnostic tool for mandibular osteomyelitis and to assess the clinical significance of CT findings. METHODS: CT images of 78 patients with mandibular osteomyelitis were reviewed. All patients were classified as cured or non-cured. Each CT finding was investigated for frequency, correlation with duration and disease cure. RESULTS: Of the 78 patients, 49 (63%) were classified as "cured" and 29 (37%) as "non-cured". Non-cured had experienced a significantly longer duration of symptoms. The most frequent CT finding was sclerosis and defect in the trabecular bone. Changes of bone width and thickening of the cortical plate were accompanied with longer disease duration. The extent of the diseased area was linearly correlated with the duration of symptoms. The significant factors to discriminate non-cured from cured were the extent of the disease, the number of findings, changes in the bone width, osteosclerosis and thickening of the cortex. Multivariate logistic regression analysis indicated that the extent of the disease and presence of changes in bone width were significant variables correlating with the cure of osteomyelitis. CONCLUSIONS: The extent of disease and the presence of change in bone width shown on CT were significantly correlated with the curability of osteomyelitis. These results indicated the usefulness and importance of CT examination for the diagnosis of mandibular osteomyelitis.

MR imaging of benign and malignant lesions in the buccal space.

OBJECTIVES: To evaluate MRI characteristics of buccal space lesions and to discuss the sensitivity of MRI in predicting malignancy of those lesions. METHODS: Thirty patients with malignant (n=7) or benign (n=23) lesions originating in the buccal space were reviewed retrospectively. MR images were assessed for the margins, internal architecture, signal intensity of lesions and their relation to the surrounding structures. RESULTS: Two cases of soft tissue sarcoma were shown as ill-defined masses with infiltration into adjacent muscles and bone. On the other hand, all tumors of minor salivary gland origin, whether malignant (n=4) or benign (n=2), were well-defined and confined within the buccal fat pad without infiltration into surrounding structures. All haemangiomas (n=9) had very high T2-weighted signal intensity. Three out of them contained signal voids on all sequences thought to represent phleboliths, a finding strongly suggestive of the diagnosis. Inflammatory lesions were characterized by the presence of edema in the surrounding fat. When ill-defined margins, infiltration into muscles and bone destruction were used as the criteria for the malignancy, only two out of seven malignant tumors were correctly diagnosed (sensitivity 29%). CONCLUSIONS: Although MR imaging was useful in demonstrating the extent of buccal space lesions, its diagnostic value in predicting malignancy was very limited. It was especially true for malignant tumors of minor salivary gland origin, which were typically seen as well-defined masses without infiltration into surrounding structures on MRI.

Early gastric carcinoma: evaluation with high-spatial-resolution MR imaging in vitro.

PURPOSE: To determine signal intensity characteristics of the gastric wall layers and to assess the accuracy of the evaluation of early gastric carcinomas in vitro by using resected specimens studied with high-spatial-resolution magnetic resonance (MR) imaging. MATERIALS AND METHODS: Fifteen gastric specimens obtained from patients suspected of having early gastric carcinoma were studied with a 1.5-T MR system with a 4-cm-diameter loop coil. High-spatial-resolution spin-echo MR images were obtained with a field of view of 50 mm, a matrix of 256 x 256, and a section thickness of 2 mm, resulting in a voxel size of 0.08 mm(3). Findings from MR images were compared with histopathologic findings. RESULTS: T1- and T2-weighted MR images clearly depicted the normal gastric wall as consisting of four and six layers, respectively, which corresponded well to the histologic layers. In 14 (93%) of 15 gastric carcinomas, the depth of mural invasion visualized with MR imaging correlated well with the histopathologic stage. The stage determined with MR imaging, however, was lower in one instance (7%) than the histopathologic stage. MR imaging also depicted the gross features of the tumor, presence of ulceration, and adjacent lymph node swelling. CONCLUSION: High-spatial-resolution MR imaging has a high diagnostic accuracy in the evaluation of the mural invasion of early gastric carcinoma in vitro and thus potentially enables preoperative histopathologic staging.

High-resolution magnetic resonance imaging of squamous cell carcinoma of the tongue: an in vitro study.

OBJECTIVES: To determine in vitro the potential of high-resolution MRI for evaluating the depth of tumor invasion of the tongue. METHODS: Twenty-one resected specimens of squamous cell carcinoma of the tongue were examined on a 1.5T MRI system with a 4 cm surface coil using four different sequences; T1W SE, T2W SE, 3D-FISP and 3D-CISS. The thickness of normal epithelium, tumor depth and width were measured on both MR images and histopathological sections. RESULTS: The mucosal epithelium, lamina propria and muscles of the tongue were clearly identifiable on MRI. All 21 carcinomas, including three early invasive carcinomas, were clearly demonstrated. A high correlation was found between the values measured by MRI and histopathology for thickness of mucosal epithelium and both depth and width of tumors. There was a good agreement between the T2W SE and the other imaging sequences for measurements of both depth and width of tumors. CONCLUSION: High-resolution MR imaging appears reliable for the in vitro evaluation of depth of tumor invasion in carcinoma of the tongue.

Superficial esophageal carcinoma: an in vitro study of high-resolution MR imaging at 1.5T.

The purpose of this study was to determine the diagnostic accuracy of high-resolution MR imaging at 1.5T for evaluating the mural invasion of superficial esophageal carcinoma. Forty-one esophageal specimens taken from patients suspected of having superficial carcinoma were studied using a 1.5T MR system with a surface coil. Spin-echo MR images were obtained with a field of view of 50mm, matrix of 256 x 256, and section thickness of 2mm (voxel size = 0.08 mm3). MR findings were compared with histopathologic findings. T2-weighted images clearly depicted the normal esophageal wall as consisting of 8 layers. In 39 (95%) of 41 carcinomas, the depth of mural invasion determined by MR imaging correlated well with that determined with histopathologic examination. The MR-based stage was higher in 2 (5%) cases than the histopathologic stage. High-resolution MR imaging at 1.5T shows a high diagnostic accuracy for evaluating the mural invasion of superficial esophageal carcinoma, thus potentially enabling preoperative histopathologic staging.

MRI of ranulas.

We reviewed the MRI of 20 patients with a ranula (8 simple and 12 plunging) and ten with other cystic masses in the floor of the mouth and/or suprahyoid portion of the neck (three haemangiomas, two neuromas, one monomorphic adenoma, one lipoma, two lateral cervical cysts and one dermoid cyst). Histological diagnoses were obtained in all cases with the exception of one presumed haemangioma. Ranulas were all well-defined, homogeneous masses giving low signal on T1- and markedly high signal on T2-weighted images. While simple ranulas were all confined to the sublingual space, plunging ranulas were centered on the submandibular space and tended to spill into one or more adjacent spaces. They extended into the sublingual space anteriorly (producing a so-called tail sign) in eight of 12 cases and into the parapharyngeal space superiorly in five. Although they sometimes filled a considerable part of the parapharyngeal space, displacement of surrounding muscles or vessels was usually slight, which was thought to reflect the nature of extravasation pseudocysts. All other cystic masses in our study had one or more MRI finding different from those of ranulas and could be easily differentiated from them.

Head and neck haemangiomas: contrast-enhanced three-dimensional MR angiography.

We evaluated the clinical effectiveness of contrast-enhanced three-dimensional (3D) magnetic resonance angiography (MRA) for diagnosing head and neck haemangiomas. We studied six patients using a magnetization prepared rapid acquisition gradient-echo (MP-RAGE) sequence on a 1.5-T system. Conventional T1- and T2-weighted and contrast-enhanced images were also obtained. The images were compared with histological findings. In four cavernous haemangiomas, a mass was partially visible as an enhancing lesion on the early phase of MRA, and was completely visible as a larger enhancing lesion in the late phase, showing slow blood flow. In two capillary haemangiomas, a mass was completely visible in the early phase showing fast flow. In all patients, MRA clearly showed both the haemangiomas and the external carotid artery branches. MRA allowed assessment of the relationship between the haemangiomas and the feeding arteries, and of the haemodynamics.

Metallic residues as a source of artifacts in magnetic resonance imaging of the temporomandibular joint.

OBJECTIVES: To establish the source of metallic artifacts on postoperative MRI of the temporomandibular joint after arthroplasty. METHODS: An experiment was carried out to evaluate MR artifacts which were thought to have been caused by minute metallic particles deposited at surgery. Four types of cutting instruments were used to cut an extracted tooth: a diamond bur attached to a dental air turbine handpiece, a steel bur and bone bur attached to a dental micromotor handpiece and a bone file. The tooth fragments were collected in plastic centrifuge tubes in water. These samples were evaluated with six MR sequences. RESULTS: MR artifacts were clearly demonstrated in samples using the bone bur and the bone file but not the diamond and steel burs. CONCLUSIONS: The artifacts seen on postoperative MRI were derived from minute metal particles from the bone bur or file used for condylar arthroplasty. Metal artifacts should be considered when interpreting postoperative MR images.

Periosteal new bone formation in the jaws. A computed tomographic study.

OBJECTIVES: To investigate the diagnostic significance of a periosteal reaction (PR) in diseases of the jaws. METHODS: The frequency of PR was investigated in 1142 patients who had undergone CT of the maxilla or mandible. The pattern of PR was categorized as either parallel, irregular, spicule or Codman's triangle. We examined the relationship of the pattern of PR to the specific disease categories of osteomyelitis, trauma, cysts, benign tumours and malignant tumors. RESULTS: Seventy patients were found to have PR. It was found in 40% of cases with osteomyelitis and 15% of malignant tumors. The only benign lesion was an eosinophilic granuloma. There were no cysts. The frequency of PR was higher in younger patient and in those with sarcomas or bone metastases compared with those with carcinomas. Ninety-one percent of the patients with osteomyelitis showed single or multi-layered PR parallel to the cortical bone, while 61% of those with malignant tumors had a spicule pattern. With the exception of Codman's triangle, none of the PR patterns were specifically associated with any one disease category. When the PR pattern was combined with the pattern of cortical bone destruction, 90% of the patients with PR could be correctly assigned to one or other of the four disease categories of osteomyelitis, trauma, benign lesion or malignant tumor. CONCLUSIONS: The pattern of PR on CT in combination with the pattern of the cortical destruction of the cortex is useful in differentiating osteomyelitis from malignant tumors.