Sixth Cranial Nerve Palsy Caused by Gastric Adenocarcinoma Metastasis to the Clivus

Tumors of the clivus and metastases to the clivus are very rare. Metastasis involving the clivus has previously been described in only two case reports. In skull metastasis, the breast and prostate are the most common primary foci, while metastasis from gastric carcinoma is extremely rare. A review of the English literature revealed only one published case of clivus metastases from gastric adenocarcinoma. There is no literature thoroughly explaining the differential diagnosis between chordoma and metastasis. Here we report a rare case of metastasis to the clivus from a gastric adenocarcinoma in a 42-year-old female patient with sudden blurry vision, presenting as bilateral cranial nerve VI palsy.

Chordoid Glioma Originating in the Intrasellar and Suprasellar Regions: Case Report

Chordoid glioma is a rare, low-grade brain neoplasm typically located in the third ventricle. Herein, we report an unusual case of histologically confirmed chordoid glioma located in the pituitary fossa and suprasellar region, not attached to the third ventricle. A 57-year-old woman presented with a 2-month history of headache and visual disturbance. Magnetic resonance imaging revealed an ovoid mass in the pituitary fossa and suprasellar region, compressing the optic chiasm without involvement of the third ventricle. The tumor showed low signal intensity on T1-weighted images and iso- to high signal intensity on T2-weighted images, with strong and homogenous contrast enhancement. Subtotal resection was performed via the transcranial approach, and the patient subsequently received adjuvant gamma knife radiosurgery. However, the residual mass showed disease progression 5 months after the initial surgery.

Acute Disseminated Encephalomyelitis Presenting as Rhombencephalitis: An Atypical Case Presentation

Acute disseminated encephalomyelitis (ADEM) is a demyelinating and inflammatory condition of the central nervous system, occurring predominantly in white matter. ADEM involving the rhombencephalon without affecting the white matter is very rare. Here, we present an unusual case of ADEM involving only the rhombencephalon in a 4-year-old Asian girl. The patient complained of pain in the right lower extremities, general weakness, ataxia, and dysarthria. The initial brain CT showed subtle ill-defined low-density lesions in the pons and medulla. On brain MRI, T2 high signal intensity (T2-HSI) lesions with mild swelling were present in the pons, both middle cerebellar peduncles, and the anterior medulla. The initial diagnosis was viral encephalitis involving the rhombencephalon. Curiously, a cerebrospinal fluid (CSF) study revealed no cellularity, and negative viral marker findings. Three weeks later, follow up brain MRI showed that the extent of the T2-HSI lesions in the brain stem had decreased. After reinvestigation, it was found that she had a prior history of upper respiratory infection. In this case, we report the very rare case of a patient showing isolated involvement of the rhombencephalon in ADEM, mimicking viral rhombencephalitis on CT and MR imaging. ADEM can involve unusual sites such as the rhombencephalon in isolation, without involvement of the white matter or deep gray matter and, therefore, should be considered even when it appears in unusual anatomical areas. Thorough history taking is important for making a correct diagnosis.

True Progression versus Pseudoprogression in the Treatment of Glioblastomas: A Comparison Study of Normalized Cerebral Blood Volume and Apparent Diffusion Coefficient by Histogram Analysis

OBJECTIVE: The purpose of this study was to differentiate true progression from pseudoprogression of glioblastomas treated with concurrent chemoradiotherapy (CCRT) with temozolomide (TMZ) by using histogram analysis of apparent diffusion coefficient (ADC) and normalized cerebral blood volume (nCBV) maps. MATERIALS AND METHODS: Twenty patients with histopathologically proven glioblastoma who had received CCRT with TMZ underwent perfusion-weighted imaging and diffusion-weighted imaging (b = 0, 1000 sec/mm2). The corresponding nCBV and ADC maps for the newly visible, entirely enhancing lesions were calculated after the completion of CCRT with TMZ. Two observers independently measured the histogram parameters of the nCBV and ADC maps. The histogram parameters between the true progression group (n = 10) and the pseudoprogression group (n = 10) were compared by use of an unpaired Student's t test and subsequent multivariable stepwise logistic regression analysis to determine the best predictors for the differential diagnosis between the two groups. Receiver operating characteristic analysis was employed to determine the best cutoff values for the histogram parameters that proved to be significant predictors for differentiating true progression from pseudoprogression. Intraclass correlation coefficient was used to determine the level of inter-observer reliability for the histogram parameters. RESULTS: The 5th percentile value (C5) of the cumulative ADC histograms was a significant predictor for the differential diagnosis between true progression and pseudoprogression (p = 0.044 for observer 1; p = 0.011 for observer 2). Optimal cutoff values of 892 x 10-6 mm2/sec for observer 1 and 907 x 10-6 mm2/sec for observer 2 could help differentiate between the two groups with a sensitivity of 90% and 80%, respectively, a specificity of 90% and 80%, respectively, and an area under the curve of 0.880 and 0.840, respectively. There was no other significant differentiating parameter on the nCBV histograms. Inter-observer reliability was excellent or good for all histogram parameters (intraclass correlation coefficient range: 0.70-0.99). CONCLUSION: The C5 of the cumulative ADC histogram can be a promising parameter for the differentiation of true progression from pseudoprogression of newly visible, entirely enhancing lesions after CCRT with TMZ for glioblastomas.

Serial MR Analysis of Early Permanent and Transient Ischemia in Rats: Diffusion Tensor Imaging and High b Value Diffusion Weighted Imaging

OBJECTIVE: To evaluate the temporal evolution and diagnostic values of the diffusion tensor imaging (DTI) and the high b value diffusion weighted imaging (DWI) in the early permanent and transient cerebral ischemia. MATERIALS AND METHODS: For permanent or 30-minute transient-ischemia induced 30 rats, DTI and DWIs at both high b (b = 3000 s/mm2) and standard b value (b = 1000 s/mm2) were obtained at the following conditions: at 15, 30, 45, 60 minutes after the occlusion of what for hyperacute permanent ischemia; at 1, 3, 5, 7, 9 hours after the occlusion for acute permanent ischemia; and at 15 minutes before reperfusion, 0.5, 2.5, and 24 hours after reperfusion for transient ischemia. The diffusion parameters and their ratios were obtained and compared between different b values, and among different time points and groups, respectively. RESULTS: For both b values, the apparent diffusion coefficient (ADC) ratio decreased for first three hours, and then slightly increased until 9 hours after the occlusion during a gradual continuous increase of DWI signal intensity (SI) ratio, with excellent correlation between ADC ratios and DWI SI ratios. The DWI showed a higher contrast ratio, but the ADC map showed a lower contrast ratio for permanent ischemia at high b value than at standard b value. Fractional anisotropy (FA) increased for 1 hour, then gradually decreased until 9 hours after the occlusion in permanent ischemia and showed transient normalization and secondary decay along with change in ADC in transient ischemia. CONCLUSION: This study presents characteristic initial elevation and secondary decay of FA, higher contrast ratio of DWI, and lower contrast ratio of ADC map at high b value, in addition to the time evolutions of diffusion parameters in early permanent and transient ischemia.

History of Korean Society of Magnetic Resonance in Medicine

No abstract available.

Pseudo Continuous Arterial Spin Labeling MR Imaging of Status Epilepticus

PURPOSE: The purpose of this study was to describe arterial spin labeling MR image findings of status epilepticus. MATERIALS AND METHODS: A retrospective chart review within our institute revealed six patients who had been clinically diagnosed as status epilepticus and had also undergone MR imaging that included ASL in addition to routine sequences. RESULTS: Six patients with status epilepticus were studied by conventional MR and arterial spin labeling imaging. All patients showed increased regional CBF correlating with EEG pathology. Notably, in two patients, conventional MRI and DWI showed no abnormal findings whereas pCASL demonstrated regional increased CBF in both patients. CONCLUSION: Arterial spin labeling might offer additional diagnostic capabilities in the evaluation of patients with status epilepticus.

Spectrum of Intracranial Parenchymal Lesions in Patients with Human Immunodeficiency Virus Infection in the Republic of Korea

The incidence of specific intracranial parenchymal lesions of HIV-infected patients varies considerably between countries. In the Republic of Korea, the number of HIV-infected patients is increasing, but little is known regarding the spectrum of intracranial parenchymal lesions in these patients. The aim of the present study was to obtain this information. To identify HIV patients with intracranial parenchymal lesions, the electronic database of radiological reports for 1,167 HIV-infected patients, seen from 1999 to 2008 at the Seoul National University Hospital, were reviewed. Neuroradiologic studies were performed on 165 of these patients, and intracranial parenchymal lesions were detected in 40 (3.4%) of them. Thirty-seven were male, and median age was 41 yr (range, 26-61). At the time of the diagnosis of intracranial parenchymal lesions, median CD4+ lymphocyte count was 40 cells/microL (range 5-560) and in 33 (82.5%) patients, it was less than 200 cells/microL. Progressive multifocal leukoencephalopathy (12 patients) is the most frequent intracranial parenchymal lesions, followed by intracranial tuberculoma (7 patients), primary central nervous system lymphoma (7 patients), intracranial cryptococcoma (4 patients), Toxoplasma encephalitis (4 patients), and disseminated non-tuberculous mycobacterial infection (3 patients).

Craniospinal Neurenteric Cysts: Various MR Imaging Features

PURPOSE: Craniospinal neurenteric (NE) cysts are rare developmental non-neoplastic cysts of the central nervous system with diverse MR imaging findings. The purpose of this study was to evaluate various MR imaging findings of intracranial and intraspinal NE cysts. MATERIALS AND METHODS: We retrospectively reviewed the MR imaging findings of six NE cysts that were confirmed by pathology. We evaluated anatomic location, signal intensity, size and enhancement pattern of NE cysts. RESULTS: Two intracranial lesions were located extra-axially in the cerebellopontine angle and quadrigeminal cisterns. Three spinal lesions were intraduralextramedullary cysts, located ventral to the spinal cord, but one thoracic lesion was an intramedullary cyst. The signal intensity of the cysts was hyperintense on T1-weighted images as compared with the cerebrospinal fluid (CSF) for two intracranial lesions and one cervical lesion. In addition, all intracranial lesions showed diffusion restriction. For the remaining three spinal lesions, the signal intensity was nearly the same as the signal intensity of the CSF as seen on both T1- and T2-weighted images. On contrast-enhanced studies, two intracranial cysts showed a small nodular enhancement and one thoracic spinal lesion showed rim enhancement. CONCLUSION: NE cysts have various locations, signal intensities, and possible focal nodular or rim enhancement. Therefore, NE cysts can be included in the differential diagnosis of various craniospinal cystic or tumorous cystic lesions.

Optimization of the Scan Protocol for the Reduction of Diaphragmatic Motion Artifacts Depicted on CT Angiography: a Phantom Study Simulating Pediatric Patients with Free Breathing

OBJECTIVE: This study was designed to optimize the scan protocol of CT angiography to reduce diaphragmatic motion artifacts in pediatric patients with free-breathing. MATERIALS AND METHODS: A phantom with twelve tubes with different diameters was constructed. To simulate free-breathing, the phantom was connected to a motor, and the phantom moved along the axis of scan. Scans were performed under several conditions: different pitch (1, 1.5) and gantry rotation time (0.37 and 0.75 sec), and different movement range (1 cm, 3 cm) and rates (20/min, 40/min). For CT scanning, a 16-channel CT scanner was used and fixed factors of the CT protocol were as follows: 100 effective mAs, 80 kVp, reconstruction with a soft-algorithm, beam collimation 16x75 mm, reconstruction thickness of 1 mm, and an interval of 0.5 mm. CT scans were repeated five times. Each tube was evaluated with the use of a grading system (0 for images where tubes were not discriminable and 2 for images where tubes were clearly discriminable). RESULTS: A higher pitch and shorter gantry rotation time produced images with a higher grade. Average grades for the higher pitch (1.5) and faster gantry rotation time (0.37 sec) for each combination of movement were as follows: 1.94 (range 1 cm and rate 20/min), 1.42 (range 1 cm and rate 40/min), 0.86 (range 3 cm and rate 20/min) and 0.52 (range 3 cm and rate 40/min). Average grades for the lower pitch (1) and slower gantry rotation time (0.75 sec) for each combination of movement were 1.08, 0.56, 0.32 and 0.08, respectively. CONCLUSION: The scanning speed and especially the pitch are important parameters for CT scans to overcome a respiratory motion artifact.

Comparison of Proton T1 and T2 Relaxation Times of Cerebral Metabolites between 1.5T and 3.0T MRI using a Phantom

PURPOSE: To present the T1 and T2 relaxation times of the major cerebral metabolites at 1.5T and 3.0T and compare those between 1.5T and 3.0T. MATERIALS AND METHODS: Using the phantom containing N-acetyl aspartate (NAA), Choline (Cho), and Creatine (Cr) at both 1.5T and 3.0T MRI, the T1 relaxation times were calculated from the spectral data obtained with 5000 ms repetition time (TR), 20 ms echo time (TE), and 11 different mixing time (TM)s using STEAM (STimulated Echo-Acquisition Mode) method. The T2 relaxation times were obtained from the spectral data obtained with 3000 ms TR and 5 different TEs using PRESS (Point-RESolved Spectroscopy) method. The T1 and T2 relaxation times obtained at 1.5T were compared with those of 3.0T. RESULTS: The T1 relaxation times of NAA were 2293 +/- 48 ms at 1.5T and 2559 +/- 124 ms at 3.0T (11.6% increase at 3.0T). The T1 relaxation times of Cho were 2540 +/- 57 ms at 1.5T and 2644 +/- 76 ms at 3.0T (4.1% increase at 3.0T). The T1 relaxation times of Cr were 2543 +/- 75 ms at 1.5T and 2665 +/- 94 ms at 3.0T (4.8% increase). The T2 relaxation times of NAA were 526 +/- 81 ms at 1.5T and 468 +/- 74 ms at 3.0T (11.0% decrease at 3.0T). The T2 relaxation times of Cho were 220 +/- 44ms at 1.5T and 182 +/- 35 ms at 3.0T (17.3% decrease at 3.0T). The T2 relaxation times of Cr were 289 +/- 47 ms at 1.5T and 275 +/- 57 ms at 3.0T (4.8% decrease at 3.0T). CONCLUSION: The T1 relaxation times of the major cerebral metabolites (NAA, Cr, Cho), which were measured at the phantom, were 4.1%-11.6% longer at 3.0T than at 1.5T. The T2 relaxation times of them were 4.8%-17.3% shorter at 3.0T than at 1.5T. To optimize MR spectroscopy at 3.0T, TR should be lengthened and TE should be shortened.

Assessment of Lymph Node Metastases by Contrast-Enhanced MR Imaging in a Head and Neck Cancer Model

OBJECTIVE: We wanted to investigate the accuracy of contrast-enhanced MR imaging for the detection of lymph node metastases in a head and neck cancer rabbit model. MATERIALS AND METHODS: The metastatic lymph node model we used was created by inoculating VX2 tumors into the auricles of six New Zealand White rabbits. T1-weighted MR images were obtained before and after injecting gadopentetate dimeglumine at three weeks after tumor cell inoculation. The sizes, signal intensity ratios (i.e., the postcontrast signal intensities of the affected nodes relative to the adjacent muscle) and the enhancement patterns of 36 regional lymph nodes (parotid and caudal mandibular nodes) were evaluated on MR images and then compared with the histopathologic findings. RESULTS: No statistical difference was found between the sizes of 12 metastatic (10.5+/-3.2 mm) and 24 hyperplastic (8.0+/-3.6 mm) lymph nodes (p > 0.05). On the contrast-enhanced T1-weighted MR images, nine metastatic and four hyperplastic lymph nodes had peripheral high and central low signal intensity, whereas three metastatic and 20 hyperplastic lymph nodes had homogeneous high signal intensity. Using a signal intensity ratio less than one as a diagnostic criterion for a metastatic lymph node, the sensitivity, specificity and positive and negative predictive values of the enhanced MR images were 75% (9/12), 83% (20/24), 69% (9/13) and 87% (20/23), respectively, with areas under receiver-operating-characteristic curve values of 0.81. CONCLUSION: This experimental study confirms that metastatic and hyperplastic lymph nodes can be differentiated using MR images on the basis of the contrast uptake patterns, but that they cannot be differentiated using any particular size criteria.

Comparison of 1.5T and 3T 1H MR Spectroscopy for Human Brain Tumors

OBJECTIVE: We wanted to estimate the practical improvements of 3T proton MR spectroscopy (1H MRS) as compared with 1.5T 1H MRS for the evaluation of human brain tumors. MATERIALS AND METHODS: Single voxel 1H MRS was performed at both 1.5T and 3T in 13 patients suffering with brain tumors. Using the same data acquisition parameters at both field strengths, the 1H MRS spectra were obtained with a short echo time (TE) (35 msec) and an intermediate TE (144 msec) with the voxel size ranging from 2.0 cm3 to 8.7 cm3. The signal to noise ratios (SNRs) of the metabolites (myoinositol (MI), choline compounds (Cho), creatine /phosphocreatine (Cr), N-acetyl-aspartate (NAA), lipid and lactate (LL)) and the metabolite ratios of MI/Cr, Cho/Cr, Cho/NAA and LL/Cr were compared at both TEs between the two field strengths in each brain tumor. The degrees of spectral resolution between the Cho and Cr peaks were qualitatively compared between the two field strengths in each brain tumor. RESULTS: The SNRs of the metabolites at 3T demonstrated 49-73% increase at a short TE (p 0.05) compared with those of 1.5T. The SNR of inverted lactate at an intermediate TE decreased down to 49% with poorer inversion at 3T (p < 0.05). There was no significant difference in the metabolite ratios between the two field strengths. The degrees of the spectral resolution at 3T were slightly superior to those of 1.5T at a short TE. CONCLUSION: As compared with 1.5T, 3T 1H MRS demonstrated 49-73% SNR increase in the cerebral metabolites and slightly superior spectral resolution only at a short TE, but little at an intermediate TE, in the brain tumors. There was no significant difference in the metabolite ratios between the two field strengths.

CT and MR Imaging of the Buccal Space: Normal Anatomy and Abnormalities

The buccal space is an anatomical compartment lying anterior to the masticator space and lateral to the buccinator muscle. Since the major purpose of imaging is to define the likely anatomic origin and also the extent of a given lesion, thorough knowledge of the normal anatomy of the buccal space is essential, and this knowledge can aid the physician in narrowing down the list of possible maladies on the differential diagnosis. We illustrate here in this paper the important anatomic landmarks and typical pathologic conditions of the buccal space such as the developmental lesions and the neoplastic lesions. Knowledge of the expected pathologic conditions is useful for the radiologist when interpreting facial CT and MR images.

Software Development for the Integrated Visualization of Brain Tumor and its Surrounding Fiber Tracts

PURPOSE: The purpose of this study was to implement a software to visualize tumor and its surrounding fiber tracts simultaneously using diffusion tensor imaging and examine the feasibility of our software for investigating the influence of tumor on its surrounding fiber connectivity. MATERIALS AND METHODS: MR examination including T1-weigted and diffusion tensor images of a patient with brain tumor was performed on a 3.0 T MRI unit. We used the skull-striped brain and segmented tumor images for volume/surface rendering and anatomical information from contrast-enhanced T1-weighted images. Diffusion tensor images for the white matter fiber-tractography were acquired using a SE-EPI with a diffusion scheme of 25 directions. Fiber-tractography was performed using the streamline and tensorline methods. To correct a spatial mismatch between T1- weighted and diffusion tensor images, they were coregistered using a SPM. Our software was implemented under window-based PC system. RESULTS: We successfully implemented the integrated visualization of the fiber tracts with tube-like surfaces, cortical surface and the tumor with volume/surface renderings in a patient with brain tumor. CONCLUSION: Our result showed the feasibility of the integrated visualization of brain tumor and its surrounding fiber tracts. In addition, our implementation for integrated visualization can be utilized to navigate the brain for the quantitative analysis of fractional anisotropy to assess changes in the white matter tract integrity of edematic and peri-edematic regions in a number of tumor patients.

Development of Korean Standard Brain Templates

We developed age, gender and ethnic specific brain templates based on MR and Positron-Emission Tomography (PET) images of Korean normal volunteers. Seventy-eight normal right-handed volunteers (M/F=49/29) underwent 3D T1-weighted SPGR MR and F-18-FDG PET scans. For the generation of standard templates, an optimal target brain that has the average global hemispheric shape was selected for each gender. MR images were then spatially normalized by linear transformation to the target brains, and normalization parameters were reapplied to PET images. Subjects were subdivided into 2 groups for each gender: the young/midlife (<55 yr) and the elderly groups. Young and elderly MRI/PET templates were composed by averaging the spatially normalized images. Korean templates showed different shapes and sizes (mean length, width, and height of the brains were 16.5, 14.3 and 12.1 cm for man, and 15.6, 13.5 and 11.4 cm for woman) from the template based on Caucasian (18.3, 14.2, and 13.3 cm). MRI and PET templates developed in this study will provide the framework for more accurate stereotactic standardization and anatomical localization.

Unusual MR Features of Extravasation of Contrast Material in Hyperacute Intracerebral Hemorrhage

Contrast extravasation in hyperacute intracerebral hemorrhage (ICH) indicative of active bleeding is a predictor of possible enlargement of hematoma, providing clinician with valid management decisions. We report unusual MR imaging features of contrast extravasation in hyperacute ICH in three patients: Case 1 with hypertension revealed dual foci of contrast extravasation, one in right basal ganglia and the other in left lateral ventricle, suggesting simultaneous bleeding of the two foci. Case 2 with presumed diagnosis of vasculitis showed relatively large area of contrast extravasation mimicking enhancing tumor or vascular lesion. Case 3 with hypertension showed the findings of active bleeding which was likely to occur during the time of MR imaging acquisition.

Unusual MR Features of Extravasation of Contrast Material in Hyperacute Intracerebral Hemorrhage

Contrast extravasation in hyperacute intracerebral hemorrhage (ICH) indicative of active bleeding is a predictor of possible enlargement of hematoma, providing clinician with valid management decisions. We report unusual MR imaging features of contrast extravasation in hyperacute ICH in three patients: Case 1 with hypertension revealed dual foci of contrast extravasation, one in right basal ganglia and the other in left lateral ventricle, suggesting simultaneous bleeding of the two foci. Case 2 with presumed diagnosis of vasculitis showed relatively large area of contrast extravasation mimicking enhancing tumor or vascular lesion. Case 3 with hypertension showed the findings of active bleeding which was likely to occur during the time of MR imaging acquisition.

A Phantom Study for Revealing Factors Related to Image Distortion of Three-Dimensional Reconstruction Rotational Angiogram

PURPOSE: To determine, by means of a phantom study, the distortion-related factors and appropriate iodine concentration for three-dimensional reconstruction rotational angiography. MATERIALS AND METHODS: Four phantoms were created: crossed metal rods, one metal rod, one contrast rod, and a contrast rod under water. Iodine concentrations were 300, 250, 200, and 150 Img/ml, respectively. For each phantom, rotational angiography was performed in the rotational, right-angled (90 degree to rotational), intermedial (45 degree), close to rotational (20 degree), and close to right-angled (70 degree) planes. Two-dimensional projection images were transferred to a workstation at which 3D images were produced using the volume rendering technique. Image quality in each plane was evaluated in terms of opacity, homogeneity, and margin sharpness, which were graded as low, intermediate or high by two neuroradiologists who used images obtained in the right-angled plane as the standard reference. The same assessors evaluated in terms of the same parameters, cross-sectional images obtained at the central, intermedial, and peripheral portions of one metal rod positioned in the right-angled, close to right-angled, and intermedial planes, and in order to compare the values at different sites, one neuroradiologist measured the horizontal and vertical diameters of each cut image. RESULTS: Three-dimensional images of all four phantoms were high quality in the close to right-angled and intermedial plane, but in the rotational and close to rotational plane were degraded. In particular, metal rod images obtained in the rotational plane were poor for all three items. In these two planes, image quality was better for the contrast rod than the metal rod, and at 200 and 250 Img/ml concentrations than at 300 and 150 Img/ml concentrations. There was no significant difference in image quality, nor in measured values of the diameter between cut images. CONCLUSION: A three-dimensional image was more distorted when a linear object was placed at a lesser angle to the rotational plane and when inherent X-ray attenuation was greater, a finding which must be closely related to the beam-hardening artifact. Distortion was least at 200-250 Img/ml of iodine concentration, the concentration thought to be most appropriate for in-vitro 3D angiography.

Buccal Space Lesions: A New Classification Based on CT and MR Imaging Findings

PURPOSE: To present a new classification based on the CT and MR imaging findings of buccal space lesions, and to propose guidelines for their radiologic differentiation. MATERIALS AND METHODS: Sixty-two histopathologically confirmed or clinically diagnosed buccal space lesions were classified on the basis of their morphologic appearance and extension to adjacent space as either (1) a mass with a distinct margin, confined to the buccal space; (2) a mass with surrounding infiltration, confined to the buccal space; or (3) a multi-space occupying mass. RESULTS: Type 1 included pleomorphic adenoma, ex-pleomorphic adenoma, carcinoma, B-cell lymphoma, acinic cell carcinoma, rhabdomyosarcoma, glomus tumor and ameloblastoma, and differentiation between malignant and benign neoplasms was not possible. Type 2 included adenoid cystic carcinoma, abscess, complicated dermoid cyst, and Kimura disease. T-cell lymphoma, neurofibroma, vascular malformation, inflammation, and foreign body granuloma pertained to type 3, and each type-3 entity showed different imaging characteristics. CONCLUSION: This new classification based on CT and MR imaging characteristics may provide useful guidelines for predicting the differential diagnosis of buccal space lesions.