Young Cheol Weon

Optimal Diffusion-Weighted Imaging Protocol for Lesion Detection in Transient Global Amnesia

BACKGROUND AND PURPOSE: Diffusion-weighted imaging (DWI) can depict small punctate hyperintense lesions in the hippocampus in transient global amnesia (TGA). The purpose of this study was to find an optimal DWI protocol for lesion detection in TGA by investigating various imaging parameters and imaging timing after symptom onset. MATERIALS AND METHODS: Sixteen patients with TGA diagnosed during 14 months underwent DWI within 24 hours and again at follow-up 3 days after onset. Each DWI session included 4 different sequences using different b-values (seconds per square millimeter) and section thicknesses (millimeter): 1000/5, 1000/3, 2000/3, and 3000/3. The presence or absence of hyperintense lesions on the 8 DWIs was determined visually, and the number of lesions detected was compared. RESULTS: Thirteen of the 16 patients (81%) had either single or multiple punctate hyperintense lesions, totaling 24 lesions, and the remaining 3 patients had no lesions. All lesions detected were in the hippocampus except 1. The number of lesions detected on initial DWIs at a b-value/section thickness of 1000/5, 1000/3, 2000/3, and 3000/3 was 3, 9, 13, and 13, respectively, whereas that of follow-up DWIs was 17, 22, 24, and 24, respectively. CONCLUSION: On the basis of these preliminary results, the highest lesion detection was achieved for DWI with b = 2000/3 mm or b = 3000/3 mm at 3 days postonset. When no lesion is detected by DWI within 24 hours after onset, follow-up DWI is recommended several days later.

Intracranial solitary fibrous tumors: imaging findings in 6 consecutive patients.

BACKGROUND AND PURPOSE: Intracranial solitary fibrous tumors (ISFTs) are rare mesenchymal neoplasms originating in the meninges. The aim of this study was to describe the CT, MR imaging, and angiographic features of the solitary fibrous tumor and to identify imaging characteristics. MATERIALS AND METHODS: We retrospectively reviewed CT, MR, and angiographic findings in 6 cases of ISFT. We evaluated the size, shape, and location of the tumor; the internal content and margin of the lesion; the pattern of enhancement; and the change of the adjacent structures. Density on noncontrast CT scans, signal intensity on MR images, and angiographic features were also documented. RESULTS: Each lesion appeared as a discrete extra-axial mass (size, 3–7 cm; mean, 5 cm). Five lesions were entirely solid, and 1 had peritumoral cyst. All 5 of the noncontrast CT scans showed hyperattenuated masses, and the tumors exhibited marked heterogeneous enhancement. No lesion contained calcification, and 2 cases showed bone invasions. On the MR images, 4 lesions showed mixed signal intensity on T2-weighted imaging. All of the lesions revealed marked heterogeneous enhancement. All of the tumors had thickening of the meninges adjacent to the tumor. Angiography showed delayed tumor blushing in all, and 3 of them had dysplastic dilation of the tumor vessels. CONCLUSION: Although there are no pathognomonic imaging findings, some imaging features, such as the “black-and-white mixed” pattern on T2-weighted images and marked heterogeneous enhancement, might be helpful in the diagnosis of intracranial solitary fibrous tumor.

Rhabdoid meningioma: clinical features and MR imaging findings in 15 patients.

BACKGROUND AND PURPOSE: Rhabdoid meningioma (RM) is a recently described variant of malignant meningioma, with radiologic features currently not well characterized in the medical literature. The purpose of this study was to describe and characterize clinical features and imaging findings associated with RM. MATERIALS AND METHODS: CT (n = 8) and MR (n = 15) images of 15 patients (4 men and 11 women; mean age, 52 years; range, 22–75 years) with 16 pathologically proved RMs along with associated clinical records were retrospectively reviewed. All of the patients underwent surgical resection and had additional radiation therapy except for 1 patient. After surgery, the patients had follow-up brain MR imaging to evaluate for tumor recurrence. RESULTS: Nine lesions (56%) were located in the cerebral convexity, and 4 lesions (25%) were located in the parasagittal areas. The tumors were isointense (n = 15) to gray matter on T1-weighted images, whereas they were hyperintense (n = 14) on T2-weighted images. On gadolinium-enhanced T1-weighted images, homogeneous enhancement was seen in 10 lesions, and heterogeneous enhancement was seen in 6 lesions that had cysts. Cystic components were noted in 6 lesions (38%). Severe peritumoral edema was seen in 12 lesions (75%). Nine lesions (56%) had hyperostosis, and 5 of them also had bone destruction. Among the 8 cases with initial CT scans, only 1 had amorphous calcifications (13%). There was only 1 recurrence of RM found during the follow-up period after surgical resection. CONCLUSION: RMs tend to have prominent peritumoral edema, cystic components, and bone involvement.

Use of Tc-99m HMPAO leukocyte scans to evaluate bone infection: incremental value of additional SPECT images.

PURPOSE In this study, the diagnostic value of Tc-99m hexamethylpropylene amine oxime (HMPAO) leukocyte scans and the role of additional SPECT in the diagnosis of bone infection were evaluated. MATERIALS AND METHODS The Tc-99m HMPAO leukocyte scans of 37 patients with clinically suspected bone infection were reviewed. The patients were divided into two groups according to the presence of orthopedic implants. Early (4 to 6 hours) and delayed (18 to 20 hours) planar images and early SPECT images were obtained. The final diagnosis of infection was made based on the pathologic, bacteriologic, and surgical data and clinical follow-up. RESULTS Group 1 (25 patients with orthopedic implants) included 15 true-positive, 1 false-negative, 7 true-negative, and 2 false-positive results. Group 2 (12 patients without orthopedic implants) included 7 true-positive, 1 false-negative, and 4 true-negative results. The overall sensitivity of the Tc-99m HMPAO leukocyte scan with SPECT to detect bone infection was 92%, with a specificity rate of 85%. (Group 1: sensitivity, 94%; specificity, 78%. Group 2: 88% and 100% sensitivity and specificity, respectively.) CONCLUSION The Tc-99m HMPAO leukocyte scan is useful in the diagnosis of bone infection, regardless of the presence of orthopedic implants. The additional SPECT images may be helpful to localize the site of infection more accurately.

Spectrum of MR Imaging Findings in Wernicke Encephalopathy: Are Atypical Areas of Involvement Only Present in Nonalcoholic Patients?

Are MRI findings different in nonalcoholic vs alcoholic Wernicke encephalopathy? Here, the authors assessed MRI in 24 patients and correlated findings with the clinical features of the disease. Despite previous reports stating that nonalcoholic Wernicke encephalopathy presents different and more extensive abnormalities, the results of this study indicate the contrary; that is, there is no difference in MRI findings between groups. The medulla was frequently affected and less than 20% of patients had the typical clinical triad. BACKGROUND AND PURPOSE: Although MR imaging is considered the most effective method to confirm a diagnosis of WE, MR imaging studies designed to distinguish WE between NA and AL patients have yielded controversial results. The purpose of this study was to determine potential differences in MR imaging features between AL and NA patients with WE and to compare neurologic symptoms with MR imaging findings. MATERIALS AND METHODS: This retrospective study included 24 consecutive patients (male/female, 15:9; mean age, 54 years) diagnosed with WE in a university hospital (AL = 13, NA = 11). Clinical manifestations and MR imaging findings between AL and NA patients were evaluated. Classic WE symptom triad and consciousness level and MR imaging findings were scored and compared with each other. Statistical analyses were performed with χ2, Fisher exact, and Spearman tests. RESULTS: No differences were observed regarding the areas of hyperintense signal intensity on FLAIR imaging and enhancement of the mammillary bodies between AL and NA patients (P > .05). Frequent sites of involvement were the medial thalami (86%), dorsal medulla (82%), tectal plate (77%), and the periaqueductal gray matter (75%). A positive association was found between the consciousness levels of the patients and the involvement of atypical sites (P = .01). Only 4 of the 24 patients (17%) had all 3 symptoms of the classic WE symptom triad. CONCLUSIONS: MR imaging features of WE may not be different between AL and NA patients. The medulla is 1 of the most frequently involved sites, and consciousness level is also associated with atypical site involvement.

Neurochemical changes in welders revealed by proton magnetic resonance spectroscopy

BACKGROUND Occupational and environmental exposure to manganese (Mn) is associated with various neurobehavioral and movement dysfunctions. However, few studies have systemically examined the neurochemical effects of Mn exposure. OBJECTIVES We examined typical changes in cerebral metabolite ratios in welders chronically exposed to Mn, compared with control individuals, using proton magnetic resonance spectroscopy (MRS), investigated whether an abnormality in brain metabolism is associated with neurobehavioral changes, and assessed possible implications of chronic Mn exposure. METHODS Thirty-five welders chronically exposed to Mn and 20 age-matched healthy subjects underwent single-voxel MRS at short echo time to assess the N-acetylaspartate (NAA), myoinositol (mI), total choline (tCho), and glutamine plus glutamate (Glx) levels, each of which was expressed as a ratio to total creatine (tCr). Neurobehavioral tests were also performed to define cognitive status. RESULTS NAA/tCr, Glx/tCr, and tCho/tCr ratios in the frontal gray matter (anterior cingulate cortex; ACC) and parietal white matter did not differ significantly between welders and control subjects. These metabolite ratios did not correlate significantly with blood Mn concentration or neurobehavioral parameters. However, mI levels in the ACC, but not in the parietal white matter, were significantly reduced in welders compared with control individuals (P<0.01). Furthermore, in the frontal lobe of the brain, the mI/tCr ratio was significantly correlated with verbal memory scores as well as blood Mn concentration (P<0.05). CONCLUSIONS The cognitive decline observed in welders exposed to Mn was associated with a decreased mI/tCr ratio in the ACC. The depletion of mI in welders may reflect possible glial cell swelling and/or detoxification processes associated with long-term exposure to Mn.

Decreased brain volumes in manganese-exposed welders

BACKGROUND A great deal of research has been devoted to identifying subclinical functional brain abnormalities in manganese (Mn)-exposed welders. However, no previous study has investigated morphological brain abnormalities, such as changes in brain volume, in welders. This study evaluates morphological changes in brain volume among welders, and investigates the relationship between structural brain abnormalities and subclinical dysfunction in this population. METHODS We used voxel-based morphometry (VBM) to assess differences in gray and white matter brain volumes between 40 welders with chronic Mn exposure and 26 age-matched control subjects. Correlation analyses were used to investigate the relationship between brain volume changes and decreased performance on neurobehavioral tests. RESULTS Brain volumes in the globus pallidus and cerebellar regions were significantly diminished in welders with chronic Mn exposure compared to controls (FDR-corrected P<0.05). These changes in brain volume were negatively correlated with cognitive performance and grooved pegboard scores. CONCLUSION There are measurable brain volume reductions in the globus pallidus and cerebellum of welders chronically exposed to Mn, and these volume reductions correlate with cognitive and motor neurobehavioral deficits. Our findings therefore indicate that volumetric measurement could be a useful subclinical marker among welders that show no signs of manganism.

Classification of persistent primitive trigeminal artery (PPTA): a reconsideration based on MRA.

Background Persistent primitive trigeminal artery (PPTA) is the most common permanent carotid-basilar anastomosis. Magnetic resonance angiography (MRA) has become the primary non-invasive imaging technique for evaluation of cerebral vascular anatomy and can provide detailed 3D imaging of intracranial vessels. Purpose To evaluate the usefulness of MRA for the detection of PPTA and to re-classify its variations based on the embryologic types of PcomA and its relationship with the basilar artery and its branches. Material and Methods Of the total 7329 patients who underwent MRA at our institution from March 2008 through November 2010, we retrospectively analyzed the MRAs of 24 patients with a PPTA. Special attention was given to defining the relationship of the PPTA and the basilar artery with PcomA and to determine the site of origin, size, and course of the PPTA. The PPTA classification included five types based on their anatomic relationship to the neighboring arteries. Clinical features and associated vascular anomalies are also described. Results Twenty-four (17 women and seven men, 34 ∼ 81 years of age, mean age 59.67 years) of the 7329 patients had a PPTA (0.33 %). Eleven cases (45.8%) were classified as type 1, three (12.5%) as type 2, five (20.8%) as type 3, one (4.2%) as type 4, and four (16.7%) as type 5b. Fifteen PPTAs (62.5%) were located on the left side and nine were located (37.5%) on the right side. The basilar artery proximal to the insertion of the PPTA showed severe to moderate hypoplasia in 13 cases (54%). Nine intracranial artery aneurysms were detected in seven (29%) of the 24 study patients. Conclusion This study revealed five types of PPTA and necessitates an adjustment of the previous classification of PPTA on the basis of our MRA examinations. A PPTA should be considered by both the clinician and the radiologist who interpret MR angiography.

A Case of Atypical Skull Base Osteomyelitis with Septic Pulmonary Embolism

Skull base osteomyelitis (SBO) is difficult to diagnose when a patient presents with multiple cranial nerve palsies but no obvious infectious focus. There is no report about SBO with septic pulmonary embolism. A 51-yr-old man presented to our hospital with headache, hoarseness, dysphagia, frequent choking, fever, cough, and sputum production. He was diagnosed of having masked mastoiditis complicated by SBO with multiple cranial nerve palsies, sigmoid sinus thrombosis, and septic pulmonary embolism. We successfully treated him with antibiotics and anticoagulants alone, with no surgical intervention. His neurologic deficits were completely recovered. Decrease of pulmonary nodules and thrombus in the sinus was evident on the follow-up imaging one month later. In selected cases of intracranial complications of SBO and septic pulmonary embolism, secondary to mastoiditis with early response to antibiotic therapy, conservative treatment may be considered and surgical intervention may be withheld.

Lymphoepithelioma-Like Carcinoma of the Breast

Lymphoepithelioma-like carcinomas (LELCs) are tumors that have similar histopathologic features to those of nasopharyngeal lymphoepithelioma, and they occur in different organs outside the nasopharynx, such as the stomach, lung, salivary gland, larynx, thyroid, and uterine cervix. 1 Lymphoepithelioma-like carcinoma of the breast is extremely rare and is a newly recognized subtype of breast carcinoma. 2 It has an infiltrating pattern similar to that of lobular carcinoma. 3,4 To the best of our knowledge, no case of LELC of the breast has been described in the radiology literature. We therefore report a case of LELC of the breast as well as the radiologic and histologic findings and a literature review.