Single-Shot Echo-Planar Diffusion-Weighted MR Imaging at 3T and 1.5T for Differentiation of Benign Vertebral Fracture Edema and Tumor Infiltration

OBJECTIVE: To compare the apparent diffusion coefficient (ADC) value using single-shot echo-planar imaging sequences at 3T and 1.5T for differentiation of benign fracture edema and tumor infiltration of the vertebral body. MATERIALS AND METHODS: A total of 46 spinal examinations were included in the 1.5T MRI group, and a total of 40 spinal examinations were included in the 3T MRI group. The ADC values of the lesion were measured and calculated. The diagnostic performance of the conventional MR image containing sagittal T2-weighted fat saturated image and each diffusion weighted image (DWI) with an ADC value with different b values were evaluated. RESULTS: The mean ADC value of the benign lesions was higher than that of the malignant lesions on 1.5T and 3T (p 0.05). The diagnostic accuracies were higher when either of the DWIs (b values of 400 and 1000) was added to routine MR image for 1.5T and 3T. Statistical differences between 1.5T and 3T or between b values of 400 and 1000 were not seen. CONCLUSION: The ADC values of the benign lesions were significantly higher than those of the malignant lesions on 1.5T and 3T. There was no statistically significant difference in the diagnostic performances when either of the DWIs (b values of 400 and 1000) was added to the routine MR image for 1.5T and 3T.

Ultrasound-Guided Percutaneous Removal of Wooden Foreign Bodies in the Extremities with Hydro-Dissection Technique

OBJECTIVE: We described the technique of ultrasound (US)-guided percutaneous removal of the foreign bodies (FB) with hydro-dissection in the radiologic department and presented video files of several cases. MATERIALS AND METHODS: Four patients referred to the radiology department for US evaluation and US-guided percutaneous removal of the FBs in the upper and lower extremities between November, 2006 and November, 2013 were included in this study. The procedures started with US evaluation for the exact location and shape of the FB. A 5 mm-sized skin incision was made at the site of the nearest point from the FB where no passing arteries or tendons were present. We adopted a hydrodissection technique to separate the FB from adjacent tissue using a 2% lidocaine solution. Injected anesthetics detached the FBs from surrounding tissue and thereby facilitated removal. After the tip of the mosquito forceps reached the FB, the wooden FBs were removed. RESULTS: The mean time required for the entire procedure was approximately 20 minutes. There were no significant complications during the US-guided removal or long-term complications after the procedure. All 4 FBs were successfully removed from the soft tissue under US guidance. CONCLUSION: Ultrasound-guided percutaneous removal of the FBs with hydro-dissection in the radiology department is a less invasive and safe method over surgical removal in the operating room. Additionally, the use of a guide wire and serial dilator may help minimize soft tissue injury and facilitate the introduction of forceps.

Various Techniques of Stent-Assisted Coil Embolization of Wide-Necked or Fusiform Middle Cerebral Artery Aneurysms : Initial and Mid-Term Results

OBJECTIVE: To evaluate the feasibility and clinical and angiographic outcomes of stent-assisted embolization for complex middle cerebral artery (MCA) aneurysms. METHODS: The records of 23 consecutive patients with 24 MCA aneurysms, who underwent stent-assisted embolization of the aneurysm, were retrospectively evaluated. RESULTS: Fifteen aneurysms were treated with one stent and 8 were treated using more than two stents (5 a stent-within-a-stent, 1 triple stents, and two Y-stent). Angiographically, complete or near complete occlusion was achieved in 15 aneurysms (65.2%), residual neck in five (21.7%), and residual aneurysm in three (13.1%). Five aneurysms demonstrated thrombosis within the stent during the procedure and hospitalization, and were resolved by intraarterial and intravenous Tirofiban injection. Symptomatic thromboembolic complications were developed in five patients and permanent deficits demonstrated in two patients with modified Rankin Scale 1 and 2, respectively. Treatment-related permanent morbidity and mortality rates were 8.3% and 0% with relatively high complication rate. Angiographic follow-up was available in 17 aneurysms at 6-31 months (mean, 13.2 months) and showed stable or improved in 15 (88.2%) and major and minor recurrence in one, respectively. CONCLUSION: Complex MCA aneurysms could be treated by stent-assisted coiling and showed lower recanalization rate during mid-term follow-up by effective flow diversion due to various stent-assisted techniques. Our results warrant further study with a longer follow-up period in a larger sample.

Diffusion-Weighted Imaging with Sensitivity Encoding (SENSE) for Detecting Cranial Bone Marrow Metastases: Comparison with T1-Weighted Images

OBJECTIVE: This study was designed to determine whether diffusion-weighted imaging (DWI) with sensitivity encoding (SENSE) could detect bone marrow involvement in patients with cranial bone marrow (CBM) metastases. DWI results obtained were compared with T1-weighted imaging (T1WI) findings. MATERIALS AND METHODS: DWI with sensitivity encoding (SENSE; b value = 1,000) was performed consecutively in 13 patients with CBM metastases diagnosed pathologically and radiologically. CBM lesions were dichotomized according to the involved site, i.e., skull base or calvarium. Two radiologists qualitatively evaluated the relative conspicuousness of CBM lesions and image qualities in B0 and in isotropic DWI and in T1WI. According to region of interest analysis of normal and pathologic marrow for these three sequences, absolute signal difference percentages (SD%) were calculated to quantitatively analyze lesion contrast. RESULTS: All 20 lesions in 13 patients with CBM metastases revealed abnormal DWI signals in areas corresponding to T1WI abnormalities. Both skull base and calvarial lesions provided better lesion conspicuousness than T1WI and B0 images. Although the image quality of DWI was less satisfactory than that of T1WI, relatively good image qualities were obtained. Quantitatively, B0 images (SD%, 82.1+/-7.9%) showed better lesion contrast than isotropic DWI (SD%, 71.4+/-13.7%) and T1WI (SD%, 65.7+/-9.3%) images. CONCLUSION: For scan times of less than 30 seconds, DWI with SENSE was able to detect bone marrow involvement, and was superior to T1WI in terms of lesion conspicuity. DWI with SENSE may be helpful for the detection of cranial bone/bone marrow metastases when used in conjunction with conventional MR sequences.

Endovascular Stent Treatment for Traumatic Common Carotid Artery Dissection with Cerebral Infarction : Case Report and Literature Review / 대한뇌혈관외과학회지

Accurate determination of the true incidence of blunt carotid artery injury is difficult because the patient may be asymptomatic or the condition may be masked by concomitant injuries. We present a case of blunt injury to the right common carotid artery and dissection with acute infarction on right fronto-temporo-parietal area and treated with carotid stent. We review the blunt carotid artery injury rate of occurrence, mechanism, presentation, screening, radiologic diagnosis, management and outcome.

Diffusion Tensor Imaging in Schizophrenia with Statistical Probabilistic Anatomical Mapping: A study of the Apparent Diffusion Coefficient Map / 신경정신의학

OBJECTIVES: Diffusion tensor imaging (DTI) studies of schizophrenia, thus far, have mainly focused on white matter abnormalities reflected in anisotropy indices such as fractional anisotropy (FA), but recently, new implications of apparent diffusion coefficient (ADC) have been proposed. This is, to our knowledge, the first study to analyze ADC maps of schizophrenic patients using statistical parametric anatomical mapping (SPAM). METHODS: DTI was performed in 20 schizophrenic patients and an equal number of age- and sex-matched healthy controls. ADC maps were then generated, from which 98 volumes of interest were extracted using SPAM. Probability-weighted mean values of ADC were calculated from each volume of interest and compared between the two groups. RESULTS: Significantly higher mean ADC values were observed in patients with schizophrenia compared to healthy controls in the following volumes of interest: hippocampal formation, bilateral uncus, right thalamus, right temporal lobe white matter, right superior temporal gyrus, bilateral insula and right lateral ventricle. CONCLUSION: The results support the recently proposed assertion that regionally increased ADC may reflect cortical brain atrophy. In addition, a new possibility is raised that a neuropathological event involving both the gray and the white matter may also play a role.

Optimized VBM in Patients with Alzheimer's Disease: Gray Matter Loss and Its Correlation with Cognitive Function

PURPOSE: To investigate the regional changes in gray matter volume by using optimized voxel based morphometry in the whole brain of patients with Alzheimer's disease (AD) and to determine its correlation with cognitive function. MATERIALS AND METHODS: Nineteen patients with AD (mean mini mental state examination (MMSE) score = 20.4) and 19 age-matched control subjects (mean MMSE score = 29) participated in this prospective study. T1-weighted 3D-SPGR scans were obtained for each subject. These T1-weighted images were spatially normalized into study-specific T1 template and segmented into gray matter, white matter and CSF. After the images were modulated and smoothed, all of the gray matter images were compared with control images by using voxel-wise statistical parametric test (two-sample t-test). RESULTS: In patients with AD, total gray matter volume was significantly smaller than normal control (552+/-39 mL vs. 632+/-51 mL, p<0.001). Significant gray matter loss was seen in both the hippocampus and amygdala complexes, and the parahippocampi and frontoparietal cortices (p<0.01, family wise error corrected). Left cerebral atrophy was more prominent than the right. Loss of gray matter volume in both the superior frontal gyri and left inferior temporal gyrus had a strong correlation with lower MMSE score. CONCLUSION: Optimized VBM was able to visualize pathologic changes of AD in vivo. In AD there was widespread gray matter volume loss in the frontoparietal lobes as well as the medial temporal lobes and had a strong correlation between volume loss of specific cortical areas and MMSE score.

Assessment of Tissue Viability Using Diffusion- and Perfusion-Weighted MRI in Hyperacute Stroke

OBJECTIVE: The aim of this study was to investigate the relationship between the diffusion and perfusion parameters in hyperacute infarction, and we wanted to determine the viability threshold for the ischemic penumbra using diffusion- and perfusion-weighted imaging (DWI and PWI, respectively). MATERIALS AND METHODS: Both DWI and PWI were performed within six hours from the onset of symptoms for 12 patients who had suffered from acute stroke. Three regions of interest (ROIs) were identified: ROI 1 was the initial lesion on DWI; ROI 2 was the DWI/PWI mismatch area (the penumbra) that progressed onward to the infarct; and ROI 3 was the mismatch area that recovered to normal on the follow-up scans. The ratios of apparent diffusion coefficient (ADC), the relative cerebral blood volume (rCBV), and the time to peak (TTP) were calculated as the lesions' ROIs divided by the contralateral mirror ROIs, and these values were then correlated with each other. The viability threshold was determined by using the receiver operating characteristic (ROC) curves. RESULTS: For all three ROIs, the ADC ratios had significant linear correlation with the TTP ratios (p < 0.001), but not with the rCBV ratios (p = 0.280). There was no significant difference for the ADC and rCBV ratios within the ROIs. The mean TTP ratio/TTP delay between the penumbras' two ROIs showed a significant statistical difference (p < 0.001). The cutoff value between ROI 2 and ROI 3, as the viability threshold, was a TTP ratio of 1.29 (with a sensitivity and specificity of 86% and 73%, respectively) and a TTP delay of 7.8 sec (with a sensitivity and specificity of 84% and 72%, respectively). CONCLUSION: Determining the viability thresholds for the TTP ratio/delay on the PWI may be helpful for selecting those patients who would benefit from the various therapeutic interventions that can be used during the acute phase of ischemic stroke.

The Contemplation of Neuropathological Abnormalities of the Corpus Callosum in Schizophrenia: A Diffusion Tensor Imaging Study / 신경정신의학

OBJECTIVES: Diffusion tensor imaging (DTI) is a new technique that can be used to visualize and measure the diffusion of water in brain tissue. It is particularly useful for evaluating white matter abnormalities. In this paper, we investigated the neuropathology of the corpus callosum in patients with schizophrenia through the new methods, diffusion tensor imaging. METHODS: Diffuse tensor imaging was performed in 19 schizophrenic patients and 26 healthy controls. One complementary measure, fractional anisotropy (FA), which is considered to be sensitive indices of axonal integrity, was obtained from regions of interest in the five areas of the corpus callosum. Neuropsychological measurement also underwent for measurement of frontal lobe function in two groups. RESULTS: There were no significant differences of FA in the DTI measures for either the schizophrenic patients compared with controls. FA was significantly decreased in women compared with men. Neuropsychological measurements such as Wisconsin card sorting test were correlated with FA of patients with schizophrenia. CONCLUSION: FA measures revealed no differences between schizophrenia and controls. The findings suggest that the structural integrity of white matter in patient with schizophrenia was not disrupted. The results are discussed in relation to previous studies reporting positive and negative findings. It is concluded that further studies using DTI in larger samples, improved and standardized methods of data acquisition and analysis are needed.

SENSE (Sensitivity Encoding) for Diffusion Tensor Imaging of the Brain

PURPOSE: The sensitivity encoding (SENSE) technique is increasingly being used with clinical MRI scanners. The object of this study is to compare the normative human data and image quality of the diffusion tensor imaging (DTI) with sensitivity encoding (SENSE) and standard single-shot EPI techniques. MATERIALS AND METHODS: 16 normal volunteers underwent single-shot echo-planar DTI with both standard and SENSE sequences using a 1.5 T Philips Intera MR scanner (TR/TE=6755/74 or 5871/66 ms, echo train length 127 or 67, NEX=3, matrix=128x128, FOV=220x220 mm, slice thickness=4 mm, b value=600 s/mm2, six orthogonal diffusion gradients). The diffusion tensor-encoded MR images were transferred to a PC workstation and analyzed using in-house software. The fractional anisotropy (FA) and apparent diffusion coefficient (ADC) maps were calculated. The presence of artifacts (ghost susceptibility, eddy current) was graded with a two- or three-point scale. The ADC and FA values were measured in the major white matter tract and gray matter nuclei. The signal-to-noise ratio was also measured. Fisher's exact test and the Mann-Whitney test were used for the statistical analysis. RESULTS: With SENSE, the acquisition time was reduced from 2 min 57 sec to 1 min 22 sec for DTI. Susceptibility artifacts (around the brain stem and temporal base) and eddy current artifacts were significantly reduced on the SENSE DTI as compared with those on the standard DTI (p<0.05). No ghost artifacts were observed on the SENSE DTI, whereas such artifacts were observed in 14 cases (87.5%) on the standard DTI. The ADC value was not significantly different between the SENSE DTI and the standard DTI, whereas the FA values in the cerebral cortex and white matter were significantly higher on the SENSE DTI than on the standard DTI (p<0.05). The signal-to-noise ratio was 8.44 on the standard DTI and 11.40 on the standard DTI. CONCLUSION: The use of SENSE DTI significantly reduces the geometric distortion caused by artifacts, shortens the acquisition time, and allows a relatively high SNR to be maintained, but tends to erroneously increase the FA value of the tissue. Therefore, DTI with SENSE may provide better white matter fiber tracking and diffusivity indices when the imaging parameters for SENSE are optimized.

Correlates of N-acetylaspartate and Cognitive Dysfunctions in Drug-naive Patients with Obsessive-compulsive Disorder: A Proton MRSI Study / 신경정신의학

OBJECTIVES: Reductions of N-acetylaspartate (NAA), a putative marker of neuronal viability, within the subcortical structures in patients with obsessive-compulsive disorder (OCD) are well documented. However, there has been no report of the NAA level in cortical structures. The authors used proton magnetic resonance spectroscopic imaging (1H-MRSI) to assess potential reductions of NAA in the frontal white matter, prefrontal gray matter, parietal gray and white matter, and the cingulate in drugnaive patients with OCD and explored the relationship between the brain metabolites and the degree to the dysfunction on the neuropsychological performances. METHODS : Thirteen drug-naive patients who met DSM-IV criteria for OCD and 13 healthy age-, sex-, handness- matched control subjects were studied. Subjects underwent MRI and 1H-MRSI and the peaks of NAA, creatine+phosphocreatine (Cr), and choline-containing compounds (Cho) were measured. Differences between patients and control subjects were tested for each metabolite ratio, and the relations between metabolite ratios and clinical symptoms, neuropsychological performances were examined. RESULTS : Upon comparison with normal controls, NAA/Cr ratio was significantly reduced in patients for the prefrontal gray matter, frontal white matter and anterior cingulate. There was no difference in Cho/Cr or NAA/Cho in any region. Also, a significant positive correlation was found between prefrontal NAA/Cr ratio and the delayed recall score of the Rey-Osterrieth Complex Figure Test in patients with OCD. CONCLUSION : The reduced NAA/Cr ratio in the prefrontal gray matter and frontal white matter suggests that OCD patients have lower neuronal viability than normal comparisons and it may be related to impaired organizational strategies in patients with OCD. These results support a role for the frontal-subcortical circuitry in a neurobiologic model of OCD.

Three Dimensional Digital Rotational Imaging in the Evaluation of the Fractures

PURPOSE: To evaluate the usefulness and the application of three dimensional digital rotational imaging (3D DRI) by the evaluation of fractures. MATERIALS AND METHODS: Sixteen patients with clinically diagnosed or suspicious fracture were involved in this study. The lesion or suspicious sites of all 16 cases were spines (n=7), pelvis (n=3) and so on (n=6; knee, elbow, ankle, wrist and foot). In all cases, conventional radiography, multiplanar 2D (slice thickness/pitch=3 or 5 mm/1:1)and volume rendering 3D reconstructed single detector helical CT (HiSpeed Advantage, GE Medical Systems, Milwaukee, WIS) scans and 3D DRI (Integris V-5000,Philips Medical Systems, The Netherlands) with multiplanar intersection and gray scaling as postprocessing technique were performed. 3D DRI was evaluated and compared with conventional radiography, multiplanar 2D CT and volume rendering 3D CT. RESULTS: 3D DRI provided more detail and additional information in 14 cases (88%), comparing with 2D and 3D CT scans. Two fractures were revealed only on 3D DRI other than conventional radiography and CT scans and one case was revealed on 2D CT and 3D DRI. In all cases, we could acquired more detail and additional information from 3D DRI than from 3D CT in the acquisition of 3D imaging. 3D DRI didn't change the classification of fracture in 12 of 13 cases (92%),which revealed the fracture on the conventional radiography or CT. CONCLUSION: 3D DRI can diagnose and evaluate the fracture rapidly and easily with anatomical and spatial resolution by acquisition of 3D imaging with postprocessing using DRI.

Guglielmi Detachable Coil Embolization of Incompletely Surgically Clipped Anterior Communicating Artery Aneurysm: Case Report

Residual intracranial aneurysm represents a continued risk of rupture and hemorrhage after incompletely surgically aneurysmal clipping. The authors describe a case of residual anterior communicating artery aneurysm after incomplete clipping, which was successfully managed by Guglielmi detachable coil(GDC) embolization. The endovascular treatment using GDC may be a good therapy for those patients in whom microsurgical clipping results in incomplete occlusion of the aneurysm and in whom reoperation is considered contraindicated or is unacceptable to patients.

The Usefulness of STIR Image in Breast MRI

PURPOSE: To assess the usefulness of STIR (short tau inversion recovery) imaging in breast MRI (magnetic resonance imaging). MATERIALS AND METHODS: We retrospectively reviewed T1- and T2-weighted (T1WI, T2WI), STIR, and dynamically enhanced images of 44 pathologically confirmed breast lesions (benign, 13; malignant, 31) in 36 patients. We selected the dynamically image which best depicted a particular lesion, and then made hard copy of the corresponding T1WI, T2WI, and STIR images. Using the dynamically enhanced image as a standard, we analysed these in terms of parenchymal pattern, lesion detectability, differentiation between benign and malignant lesions, extent, multifocality, and the ductal system. The results were statistically analyzed. RESULTS: In 33 of 44 cases (75%), detectability was greater at STIR imaging than at T1- and T2WI, especially in fibrofatty or fatty breast (14/14 cases, p<0.05). STIR images did not always differentiate between benign and malignant lesions, and extent (50%) and multifocality (46%) were commonly exaggerated compared with T1- and T2WI. In 18 of 44 cases (41%), STIR images suggested the presence of ductal structures. CONCLUSION: For the detection of lesions, STIR imaging was more useful than T1- and T2WI, though STIR did not differentiate between benign and malignant lesions. The extent and multifocality of a lesion were exaggerated on STIR images, compared with T1- and T2WI.

Acute Appendicitis: Sensitivity, Specificity and Diagnostic Accuracy of Thin-Section Contrast-Enhanced CT Findings

PURPOSE: To assess the sensitivity, specificity, and diagnostic accuracy of individual contrast-enhanced helical CT findings of acute appendicitis. MATERIALS AND METHODS: We retrospectively reviewed the appendiceal helical CT scans, obtained after intravenous contrast administration (abdomen; 7-mm collimation, abdominopelvic junction; 5-mm collimation), of 50 patients with surgically proven acute appendicitis and 112 with alternative diagnoses. The following parameters were analysed by three radiologists: enlarged appendix (> 6 mm in diameter), appendiceal wall thickening, appendiceal wall enhancement, no identification of the appendix, appendicolith(s), (appendiceal) intraluminal air, (appendiceal) intraluminal air extraluminal air, periappendiceal fat stranding, extraluminal fluid, phlegmon, abscess, lymphadenopathy, terminal ileal wall thickening, focal cecal apical thickening, focal colonic wall thickening, and segmental colonic wall thickening. RESULTS: The CT findings of acute appendicitis that statistically distinguished it from alternative diagnoses were an enlarged appendix (sensitivity; 92%, specificity; 93%, diagnostic accuracy; 93%), appendiceal wall thickening (for these three parameters: 68%, 96% and 88%, respectively), periappendiceal fat stranding (90%, 79%, 82%), appendiceal wall enhancement (72%, 86%, 82%), appendicolith (16%, 100%, 74%), and focal cecal apical thickening (14%, 100%, 74%) (for each, p < 0.05). CONCLUSION: On thin-section contrast-enhanced helical CT, an enlarged appendix and periappendiceal fat stranding were found in 90% or more patients with acute appendicitis. Appendiceal wall thickening and enhancement were clearly demonstrated and significant findings for diagnosis. Less common but specific findings include appendicolith, focal cecal apical thickening and intramural air, can also help us establish a diagnosis of acute appendicitis.

The Diagnostic Value of Contrast Enhanced Power Doppler US on Small Breast Lesions

PURPOSE: To evaluate the usefulness of contrast-enhanced power Doppler ultrasonography (PDUS) in differentiating small benign from small malignant breast lesions. MATERIALS AND METHODS: Thirty-one solid breast lesions (<2 cm in size; 17 benign and 14 malignant) prospectively underwent US and PDUS before and after the injection of contrast agent (SH U 508A). Morphologic analysis involved independent assessment of the findings of US and the patterns of Doppler signals before and after contrast enhancement at PDUS, and sensitivity and specificity were thus evaluated. The diagnostic accuracy of US accompanied by PDUS was also determined before and after contrast enhancement. Hemodynamic analysis involved measurement of the time lapse between contrast injection at PDUS and observed change in Doppler signals. For this, a sonic VIOR computer-assisted program was used and the results were correlated with the pathologic findings. RESULTS: The sensitivities of US before and after contrast enhanced PDUS were 100%, 35.7%, and 57%, with specificities of 47%, 88.2% and 76%, respectively. The diagnostic accuracy of US was 35% with noncontrast PDUS, and 77% before and after contrast enhanced PDUS. The recorded time lapse between contrast injection at PDUS and observed change in Doppler signals did not correlate closely with the pathologic findings. CONCLUSION: In that it improved visualization of the morphology of vascular Doppler signals, microbubble contrast-enhanced PDUS complemented US and PDUS in differentiating between small benign and small malignant breast lesions.

Interpretation of simple X-ray film

No Abstract Available.

Papillary Tumors of the Breast: US Findings of the Benign and Malignant Lesions

PURPOSE: To determine which sonographic findings usefully differentiate between benign and malignant papillary tumors. MATERIALS AND METHODS: We retrospectively rev i ewed the ultrasonographic findings of 42 surgically proven cases of papillary breast lesions [11 malignant lesions (7 inva s i ve papillary carcinomas, 4 intraductal papillary carcinomas) and 31 benign intraductal pa-pillomas]. All 42 cases were classified sonographically as cystic or ductal, or solid type, and the shape, wall change, margin, internal echo-pattern, posterior echo change and other associated findings for the two types were then analysed. RESULTS: Among the 25 cases (5 malignant and 20 benign) of cystic or ductal type, tubular shaped lesions were more frequently benign (60%). In all 20 benign lesions the wall of cystic portion was well-defined, smooth and thin. The solid portion of the cystic type showed an illdefined irregular margin in four malignant lesions (80%) and a smooth margin in 19 which were benign (95%). The internal echo-pattern was heterogeneous mixed-echo in three cases of malignancy, and homogeneously hypoechoic in 19 benign lesions (95%). Posterior enhancement was seen in two malignant lesions (40%), while in 19 benign lesions (95%), there was no posterior echo change. There were 17 solid type lesions (6 malignant cases, 11 benign cases), and most of these, whether benign or malignant, were smooth, oval or lobulated, hypoechoic masses. Posterior enhancement, howeve r, was more frequently observed in malignant lesions (three cases, 50%) than in those which were benign (one case, 9%). CONCLUSION: In cystic or ductal type lesions, an ill-defined irregular thick cystic wall, an illdefined irregular margin, a heterogeneous mixed internal echo-pattern and posterior enhancement of the solid portion suggested malignancy. In solid type lesions, posterior enhancement was more frequently found in malignant than in benign lesions.

Interactive Atlas Using Web Bowser: CT and MRI of the Temporal Bone

PURPOSE: The purposes of this study were to construct an interactive atlas of the temporal bone using a web-browser and to provide a template for web-based teaching files, using free and shared applets and scripts on the internet. MATERIALS AND METHODS: HRCT and MR images of the temporal bone including its normal anatomy, tumors, trauma, inflammation, anomalies and vascular diseases were used in this study. Acquired radiologic images were transformed to GIF/JPG formats and to achieve appropriate image quality, were retouched. Text and image files of normal anatomy and diseases were written by HTML. JavaScript and applets were inserted in the HTML files for the interactive display of images and texts. In order to review anatomic features and diseases, a sarch index was also attached to the last part of the file. RESULTS: Using interactive images and texts, temporal bone anatomy and disorders were displayed. Scripts and applets were also useful for indicating specific points of interest when a mouse was placed over the anatomic sites. The atlas may be viewed in the form of a CD-ROM, or via the internet using any computer platform or web-browser. CONCLUSION: This web-based teaching file of the temporal bone offers dynamic and interactive education. It can be usefully employed as a template for the production of interactive educational materials, offering JavaScript and Providing suitable input for classes. It can replace texts and imaging contents.

Absent Bow-Tie Sign in Knee MRI

PURPOSE: 'Absent bow-tie sign'is interpreted as positive when a bow-tie-shaped body segment is seen on only one or no slice of 4- or 5-mm thick sagittal images, and is a well known as a useful sign in diagnosing bucket-handle meniscal tears. In practice, however, we have found that this sign was also positive in certain cases other than bucket-handle tears. We have assumed that if the normal range of meniscal body width, as determined among Westerners, is transferred to the Korean population without verification and modification this might lead to misdiagnosis. The purpose of this study, therefore, is to examine the reliability of the 'absent bow-tie sign'. MATERIALS AND METHODS: Among 454 cases in which knee MRI had been performed, we retrospectively evaluated 862 menisci, the total remaining after cases of discoid meniscus or those involving previous meniscectomy had been excluded. Among the 862 menisci, 614 were normal, 97 showed degeneration, 43 showed buck-et-handle tearing, and 108 showed tears other than bucket-handle tear. In all cases, proton-denwity and T2-weighted images were obtained in both sagittal and coronal planes, with 3mm section thickness and 1mm gap. We recorded the number of sagittal images in which the body segment of each meniscus had a bow-tie appear-ance, and measured the width of each meniscal body, as seen on midcoronal images. RESULTS: In all cases but one of bucket-handle tears (97.7%), the bow-tie sign was absent, as it was in 73.2% ofnon-bucket-handle tears, 35.0% of degenerated menisci and 27.5% of normal menisci. Among the non-tear group, 56.4% of menisci in the female group and 27.1% in the male group had bodies less than 9mm wide. CONCLUSION: In the diagnosis of bucket-handle tears, the 'absent bow-tie sign'is a very sensitive indicator. It is nonspecific, however, and merely suggests some significant deficiency in the meniscus body or small menis-ci,so can be positive in other cases. Thus the interpreter should be aware of the characteristics of this sign especially when used to interpret MRI of the knee of a female Korean patient.