Hidenobu Matsuzaki

The value of dynamic contrast-enhanced MRI in diagnosis of malignant lymphoma of the head and neck

In this study, we attempted to diagnose malignant lymphoma on the basis of magnetic resonance imagings (MRIs) and dynamic contrast-enhanced MRI (DCE-MRI). Eighteen lesions (in eight patients), all of which had been proven histopathologically, were detected on MRI. The eight patients included five patients with diffuse large B-cell lymphoma, one with B-cell low-grade MALT lymphoma, one with follicular lymphoma, and one with Hodgkins lymphoma. Nine lesions were located in the submandibular region, three in the buccal region, two in the orbit region, two in the submental region, and one each in the palatal and tonsil regions. The diameter of the lesions ranged between 9 and 42.2 mm (average: 22.4 mm). The signal intensities (SIs) of the 18 lesions were examined on T1-weighted (T1WI), T2WI, and gadopentetate (Gd)-T1WI. One lesion in case 8 was excluded from DCE-MRI findings, i.e., the regions of interest could not be adequately set on DCE-MRIs. The contrast index (CI) curves of the remaining 17 lesions were prepared. All 18 lesions showed almost the same images on T1WI, T2WI, and Gd-T1WI, although they represented four types of lymphoma. The images showed homogeneous SI that was intermediate to slightly high SI on T1WI, slightly high SI on T2WI, and moderately enhanced on Gd-T1WI. Thus, the cases of malignant lymphoma in this study showed relatively characteristic features based on MRI; however, these features might be non-specific. The CI curves in this study showed a relatively rapid increase, reaching a maximum CI at 45-120 s, and a relatively rapid decrease in most lesions (14/17; 82.4%); on the other hand, the curves of 3 of the 15 lesions (17.6%) showed relatively rapid increase, sustenance of a plateau, and a gradual decrease thereafter. These patterns of CI curves may indicate characteristic features useful for distinguishing malignant lymphomas from other lesions.

Assessment of dynamic MRI of Warthin’s tumors arising as multiple lesions in the parotid glands

We examined three patients with multiple synchronous Warthins tumors in the bilateral parotid and described the value of using dynamic MRI. The time course of the contrast index (CI curves) was calculated from a dynamic series. Warthins tumors showed intermediate signal intensity on T1WI, heterogeneous high and intermediate signal intensity on T2WI and a slight enhancement on Gd-T1WI. Warthins tumors of CI curves showed specific findings. CI curves in each lesion showed the same pattern. It was difficult to diagnose masses as Warthins tumors using only MR images on T1, T2 and Gd-T1WI. Dynamic MRI can distinguish Warthins tumors from other possible tumors except for oncocytoma. Therefore, the use of dynamic MRI is recommended as a diagnostic method for Warthins tumors in multiple synchronous lesions of the parotid gland.

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.

MR imaging of nasopalatine duct cysts

We describe the magnetic resonance (MR) features of two cases of nasopalatine duct cyst (NPDC), including the first presentation of T1-weighted images (WI). The signal intensity of the cases of NPDC showed homogeneous high signal intensity on both on T1 and T2WI, although most cysts of maxillofacial regions demonstrate low to intermediate signal intensity on T1WI. NPDC may commonly be of high signal intensity on T1WI, which is consistent with keratin and viscous fluids.

Diagnostic value of MRI for odontogenic tumours

OBJECTIVES To evaluate the diagnostic value of MRI for odontogenic tumours. MATERIALS AND METHODS 51 patients with odontogenic tumours were subjected to pre-operative MRI examinations. For tumours with liquid components, i.e. ameloblastomas and keratocystic odontogenic tumours (KCOTs), the signal intensity (SI) uniformity of their cystic components (UΣ) was calculated and then their UΣ values were compared. For tumours with solid components that had been examined using dynamic contrast-enhanced MRI (DCE-MRI), their CImax (maximum contrast index), Tmax (the time when CImax occurred), CIpeak (CImax × 0.90), Tpeak (the time when CIpeak occurred) and CI300 (i.e. the CI observed at 300 s after contrast medium injection) values were determined from CI curves. We then classified the odontogenic tumours according to their DCE-MRI parameters. RESULTS Significant differences between the UΣ values of the ameloblastomas and KCOT were observed on T1 weighted images, T2 weighted images and short TI inversion recovery images. Depending on their DCE-MRI parameters, we classified the odontogenic tumours into the following five types: Type A, CIpeak > 2.0 and Tpeak < 200 s; Type B, CIpeak < 2.0 and Tpeak < 200 s; Type C, CI300 > 2.0 and Tmax < 600 s; Type D, CI300 > 2.0 and Tmax > 600 s; Type E, CI300 < 2.0 and Tmax > 600 s. CONCLUSION Cystic component SI uniformity was found to be useful for differentiating between ameloblastomas and KCOT. However, the DCE-MRI parameters of odontogenic tumours, except for odontogenic fibromas and odontogenic myxomas, contributed little to their differential diagnosis.

Usefulness of MRI and dynamic contrast-enhanced MRI for differential diagnosis of simple bone cysts from true cysts in the jaw

INTRODUCTION It can be difficult to differentiate simple bone cysts (SBCs) from true cysts in the jaw when these lesions appear unilocular. The present study reports the MR imaging of subjects with SBCs and describes the diagnostic value of the MRI findings. MATERIALS AND METHODS Ten subjects with SBCs in the jaw were examined using MRI. T1- and T2-weighted images (T1WI, T2WI) were obtained, and contrast-enhanced images and dynamic contrast-enhanced MRI (DCE-MRI) were acquired. RESULTS In all cases, the contrast-enhanced T1WI acquired approximately 6 minutes after the administration of Gd-DTPA showed marked enhancement of the margin and slight enhancement of the inner part of the cyst cavity. In all cases, the time-signal intensity (SI) curves show a gradual increase in the SI until approximately 15 minutes after the administration of Gd-DTPA. These findings might not be observed on the DCE-MRIs of the other true cysts with epithelial lining that show no enhancement in a cavity. CONCLUSION MRI, especially DCE-MRI, can provide useful information for distinguishing SBCs from other cysts.

Diagnostic value of dynamic contrast-enhanced MRI for unilocular cystic-type ameloblastomas with homogeneously bright high signal intensity on T2-weighted or STIR MR images

Typical MR images of ameloblastomas on T2-weighted image (WI) or short inversion time inversion-recovery (STIR) show multiple bright high-signal-intensity loci on a high-signal-intensity background. Unilocular cystic-type ameloblastomas show homogeneously bright high signal intensity on T2WI or STIR as a water-like signal intensity. Therefore, it is difficult to distinguish unilocular cystic-type ameloblastoma from other cystic lesions such as keratocystic odontogenic tumors, radicular cysts (residual cysts) and dentigerous cysts only on the basis of MRI signal intensity. In the present study, we evaluated whether contrast-enhanced (CE)-T1WI and dynamic CE-MRI (DCE-MRI) could provide additional information for differential diagnosis in unilocular cystic-type ameloblastoma. Images from 12 cases of suspected unilocular cystic-type ameloblastoma were evaluated in the present study. Of them, 5 had areas suspected of indicating a solid component on T1WI and T2WI (or STIR). Ten had undergone additional CE-T1WI and DCE-MRI. On 5 of 10 cases of CE-T1WI, a tiny enhancement area was detected. On 6 of 10 DCE-images, a time-course enhanced area which was suspected to be a solid component was detected. CE-T1WI was helpful in the diagnosis of ameloblastoma because the tiny enhanced areas were taken to indicate possible solid components. Moreover, the rim-enhancement area on CE-T1WI could be divided into small regions of interest, and some of these showed slightly increased enhancement on DCE-MRI, which was taken to indicate a solid component and/or intramural nodule with focal invasion of ameloblastoma tissue. DCE-MRIs of the four remaining cases, which provided no clues to the diagnosis of ameloblastoma in the manner of the above descriptions, showed thicker rim enhancement than odontogenic cysts. Thus, CE-T1WI and DCE-MRI were helpful in the differential diagnosis of unilocular cystic-type ameloblastomas with homogeneously bright high signal intensity on T2WI or STIR.

Incidentally found and unexpected tumors discovered by MRI examination for temporomandibular joint arthrosis

We examined the frequency of incidentally found or unexpected tumors discovered at the time of magnetic resonance imaging (MRI) examinations in the temporomandibular joint (TMJ) region for patients with suspicion of TMJ arthrosis. Five MR images (T1-weighted transverse scout image and proton density and T2-weighted oblique sagittal images at the open and closed mouth) were acquired. In 2776 MRI examinations of TMJ arthrosis, two tumors were discovered. They consisted of an adenoid cystic carcinoma in the deep portion of the parotid gland, and a malignant tumor extending from the infratemporal fossa to the parapharyngeal space. The rate of incidentally founded or unexpected tumors in TMJ examinations was low (0.072%), but the two tumors found were malignant tumors, and therefore, scout image should be carefully examined, not only used for positing the slice.

Ameloblastic carcinoma: a case report with radiological features of computed tomography and magnetic resonance imaging and positron emission tomography.

Ameloblastic carcinoma is a rare malignant odontogenic carcinoma that has metastatic potential, and because of its rare incidence, there are few reports focusing on its radiologic imaging. If it shows aggressive appearances, it can be diagnosed as malignant tumor. But in case of negative appearance, it is difficult to distinguish ameloblastic carcinoma from ameloblastoma. We report a case of ameloblastic carcinoma of the maxilla in a 76-year-old female patient with radiologic images and pathologic features.

Solid-type primary intraosseous squamous cell carcinoma of the mandible: a case report with histopathological and imaging features

Primary intraosseous squamous cell carcinoma (PIOSCC) is a rare malignant odontogenic tumor arising from odontogenic epithelial remnants within the jawbones. PIOSCC is histopathologically divided into 3 types: solid-type carcinoma, carcinoma derived from a keratocystic odontogenic tumor, and carcinoma derived from an odontogenic cyst. In this article, we report a case of solid-type PIOSCC involving reactive bone formation in the mandible in a 60-year-old female patient together with its histopathological and imaging findings.