Biomedical subjects

Eung Yeop Kim

Publications and source records attributed to Eung Yeop Kim.

9 recordsLinked to original sources

PubMed2006

Assessment of regional GABA(A) receptor binding using 18F-fluoroflumazenil positron emission tomography in spastic type cerebral palsy.

Periventricular leukomalacia (PVL) due to hypoxic-ischemic insult to the immature brain, chorioamnionitis and maternal infection are the major etiological factors of spastic type cerebral palsy (CP). Despite advances in preventing and treating certain causes of CP, the number of patients has remained essentially unchanged and the pathophysiological mechanisms related to motor dysfunction remain poorly understood. In this study, statistical parametric mapping (SPM) analysis of cerebral gamma-aminobutyric acid (GABA) receptor PET imaging using [18F]-fluoroflumazenil showed increased GABA(A) receptor binding in the bilateral motor and visual cortices in spastic diplegia (SD) type CP patients (n = 20) compared with normal controls (n = 10). As GABA(A) receptor signaling modulates biological perception and production of movement, complex motor skills and use-dependent plasticity in the motor cortex, increased GABA(A) receptor binding in the motor cortex might play a important role in poor motor control. Decreased GABA(A) receptor binding was seen in the brain stem in SD CP patients, which appears to be related to spastic symptom.

Adolescent↗

PubMed2005

Detection of thrombus in acute ischemic stroke: value of thin-section noncontrast-computed tomography.

BACKGROUND AND PURPOSE: Previous studies on the hyperdense middle cerebral artery (MCA) sign were conducted using > or =5-mm thickness noncontrast-computed tomography (NCT). The purpose of this study was to compare thin-section NCT with 5-mm NCT in the detection of thrombus in acute ischemic stroke. METHODS: Enrolled were consecutive 51 patients with acute infarction in the anterior or MCA territory. All patients underwent both 5-mm NCT and either 1.25- or 1-mm thin-section helical NCT within 6 hours of symptom onset. Patients were assigned to either the single or multisegmental occlusion group, depending on the thrombus extent on thin-section NCT. Thin-section NCT and 5-mm NCT were compared in the detection of thrombi. RESULTS: Thrombi were identified in 45 patients (88%) on thin-section NCT and 16 on 5-mm NCT (31%; P<0.001). No occlusion was seen in 6 patients. Both sensitivity and specificity of thin-section NCT in detection of thrombus were 100%. CONCLUSIONS: Acute thrombus can be detected with higher sensitivity on thin-section NCT than on 5-mm NCT, and its extent is more accurately determined on thin-section NCT.

Aged↗

PubMed2005

CT sign of brain swelling without concomitant parenchymal hypoattenuation: comparison with diffusion- and perfusion-weighted MR imaging.

PURPOSE: To retrospectively evaluate the apparent diffusion coefficient (ADC) on magnetic resonance (MR) images and the perfusion parameters of lesions that show brain swelling without concomitant parenchymal hypoattenuation on computed tomographic (CT) scans. MATERIALS AND METHODS: Review board approval was obtained, and informed consent was waived. A total of 14 patients (seven men and seven women; mean age, 64 years +/- 11) were retrospectively selected from the consecutive 172 patients with acute cerebral ischemia who underwent CT within 6 hours of symptom onset. All patients had brain swelling without parenchymal hypoattenuation, including loss of gray-white matter distinction on CT scans, and they underwent diffusion- and perfusion-weighted MR imaging shortly after CT. CT attenuation, ADC, and perfusion parameters of relative cerebral blood volume (CBV), time to peak (TTP), and relative cerebral blood flow (CBF) were calculated for gray and white matter of the lesion. The measured values were compared with those of the contralateral hemisphere by using the paired t test; comparison of values of perfusion parameters among three subgroups was performed with the Kruskal-Wallis test. Arterial occlusions were determined with MR angiography or conventional angiography. RESULTS: The mean interval between initial CT and MR imaging was 2.4 hours +/- 0.9 (range, 0.4-3.4 hours). The ADC of lesions was similar to that of contralateral normal tissue (mean ADC ratio for gray matter and white matter, 0.99 and 0.97, respectively) (P > .05). Lesions had an increased relative CBV (P < .001), a mild to moderate TTP delay (P < .001), and a variable but not statistically significant reduction of relative CBF. The mean relative CBF of gray matter was less in patients who had complete infarction (0.81 +/- 0.16) than that in patients with partial infarction (0.99 +/- 0.16) or those with a normal radiologic outcome (1.12 +/- 0.22), but this difference was not statistically significant (P > .05). Proximal cerebral artery occlusions were found in all patients. In five (36%) patients, the lesion did not progress to infarction at follow-up. CONCLUSION: The CT sign of brain swelling without concomitant parenchymal hypoattenuation in patients with acute cerebral ischemia does not represent severe ischemic damage and may suggest ischemic penumbral or oligemic tissue.

Aged↗

PubMed2005

Prediction of hemorrhagic transformation in acute ischemic stroke: role of diffusion-weighted imaging and early parenchymal enhancement.

BACKGROUND AND PURPOSE: MR imaging may help in predicting hemorrhagic transformation (HT) in acute ischemic stroke. Our purpose was to determine whether the lesion volumes on diffusion-weighted (DW) imaging, apparent diffusion coefficient (ADC) values, and early parenchymal enhancement are predictive of HT and to investigate the mechanism of the enhancement. METHODS: We retrospectively examined 55 patients with acute ischemic stroke who underwent gadolinium-enhanced MR imaging within 6 hours of symptom onset and follow-up CT or MR imaging within 72 hours. Intravenous thrombolysis was performed in 15 patients. DW imaging lesion volumes and ADC values were compared between patients with and those without HT. ADCs and perfusion parameters were compared between lesions with and those without parenchymal enhancement. RESULTS: Nineteen (34.5%) patients had HT (14 with hemorrhagic infarction, five with parenchymal hematoma). Patients with HT had decreased mean ADCs and large lesion volumes on DW imaging, but differences were not significant (P > .05). HT occurred in five patients (100%) with parenchymal enhancement, which corresponded to the site of HT. In enhancing lesions, the ADC ratio (0.76 +/- 0.06) was slightly higher and the delay in time to peak (0.10 +/- 2.79) was less than respective values in the rest of the ischemic lesion (0.66 +/- 0.06 and 8.79 +/- 4.86, respectively; P = .068). CONCLUSION: Early parenchymal enhancement is highly specific for HT and may be associated with early reperfusion and damage to the blood-brain barrier in ischemic tissue. DW imaging lesion volumes and ADC values had no strong relationship with HT.

Aged↗

PubMedDate not supplied

Multiphasic perfusion computed tomography in hyperacute ischemic stroke: comparison with diffusion and perfusion magnetic resonance imaging.

PURPOSE: The purpose of this study was to compare multiphasic perfusion computed tomography (CT) with diffusion and perfusion magnetic resonance imaging (MRI) in predicting final infarct volume, infarct growth, and clinical severity in patients with hyperacute ischemia untreated by thrombolytic therapy. METHOD: Multiphasic perfusion CT was performed in 19 patients with ischemic stroke within 6 hours of symptom onset. Two CT maps of peak and total perfusion were generated from CT data. Diffusion-weighted imaging (DWI) and perfusion MRI were obtained within 150 minutes after CT. Lesion volumes on CT and MRI were compared with final infarct volume and clinical scores, and mismatch on CT or MRI was compared with infarct growth. RESULTS: The lesion volume on the CT total perfusion map strongly correlated with MRI relative cerebral blood volume (rCBV), and that on the CT peak perfusion map strongly correlated with MRI relative cerebral blood flow (rCBF) and rCBV (P < 0.001). The lesion volume on unenhanced CT or DWI moderately correlated with final infarct volume, but only lesion volume on unenhanced CT weakly correlated with baseline clinical scores (P = 0.024). The lesion volumes on the CT peak perfusion map and MRI rCBF similarly correlated with final infarct volume and clinical scores and more strongly than those on mean transit time (MTT) or time to peak (TTP). DWI-rCBF or CT mismatch was more predictive of infarct growth than DWI-MTT or DWI-TTP mismatch. CONCLUSION: Multiphasic perfusion CT is useful and of comparable utility to diffusion and perfusion MRI for predicting final infarct volume, infarct growth, and clinical severity in acute ischemic stroke.

Acute Disease↗

PubMedDate not supplied

Primary peripheral T-cell lymphoma of the face other than mycosis fungoides. Computed tomography and magnetic resonance findings.

OBJECTIVE: To describe the radiologic findings of primary peripheral T-cell lymphoma (PTCL) of the face other than mycosis fungoides. METHODS: Computed tomography (CT) and magnetic resonance imaging (MRI) findings of 5 consecutive patients with pathologically proven primary facial PTCL other than mycosis fungoides were retrospectively evaluated. Patients with PTCL involving the sinonasal cavity or lymph nodes were excluded. RESULTS: Diagnoses of patients included in this study consisted of natural killer/T-cell lymphoma (n = 2), subcutaneous panniculitis-like T-cell lymphoma (n = 1), anaplastic large cell lymphoma (n = 1), and PTCL not otherwise specified (n = 1). Infiltration or swelling of the superficial space of the face was noted on both CT and MRI, mimicking inflammation or infection. Also seen were well-enhancing small nodular (n = 2) or infiltrative mass-like lesions (n = 2) within the areas of infiltration, which showed intermediate signal intensity on T2-weighted images. One patient demonstrated infiltration and swelling alone. CONCLUSIONS: Primary facial PTCL is a rarely encountered tumor and demonstrates infiltration or swelling mimicking inflammation or infection. Nodular or infiltrative mass-like lesions may be helpful for its diagnosis.

Adult↗

PubMedDate not supplied

Sulcal hyperintensity on fluid-attenuated inversion recovery imaging in acute ischemic stroke patients treated with intra-arterial thrombolysis: iodinated contrast media as its possible cause and the association with hemorrhagic transformation.

OBJECTIVE: To investigate the effect of iodinated contrast medium on sulcal hyperintensity on fluid-attenuated inversion recovery (FLAIR) imaging immediately after intra-arterial thrombolysis in patients with acute ischemic stroke and to determine whether it may be associated with subsequent hemorrhagic transformation (HT). METHODS: Fourteen consecutive patients with acute ischemic stroke who were treated with intra-arterial thrombolysis were enrolled. All patients underwent noncontrast computed tomography (NCT) and diffusion-weighted (DWI), perfusion-weighted, gradient-recalled echo (GRE), and gadolinium-enhanced T1-weighted magnetic resonance imaging (MRI). Immediate follow-up NCT and MRI (T2-weighted, FLAIR, GRE, DWI, perfusion-weighted, T1-weighted, and gadolinium-enhanced T1-weighted) were obtained and evaluated to determine the presence of sulcal hyperintensity or subarachnoid hemorrhage (SAH). The same follow-up images were obtained on days 1, 3, and 7 and evaluated to determine HT. RESULTS: Sulcal hyperintensity was found in 8 (57.1%) of 14 patients and was seen as hyperattenuation on immediate follow-up NCT and as hyperintensity on T1-weighted images in 4 (50%) of 8 patients. It may be suggested that the sulcal hyperattenuation was responsible for the sulcal hyperintensity, considering signal intensity and follow-up imaging. All patients with sulcal hyperintensity showed enhancement in the corresponding gyri on gadolinium-enhanced T1-weighted imaging. Hemorrhagic transformation developed in 5 of 8 patients with sulcal hyperintensity and in 1 of 4 patients without (P = 0.031). CONCLUSIONS: In acute ischemic patients treated with intra-arterial thrombolysis, sulcal hyperintensity on FLAIR imaging may be caused by iodinated contrast medium, which should not be considered SAH. Sulcal hyperintensity is significantly associated with subsequent HT.

Acute Disease↗

PubMedDate not supplied

Idiopathic synovial osteochondromatosis of the hip: radiographic and MR appearances in 15 patients.

OBJECTIVE: To evaluate the radiographic and MR appearance of idiopathic synovial osteochondromatosis of the hip. MATERIALS AND METHODS: Radiographs and MR images of 15 patients with idiopathic synovial osteochondromatosis of the hip were assessed. The former were analysed in terms of the presence of 1) juxta-articular calcified and/ or ossified bodies, 2) osteophytes, 3) bone erosion, 4) juxta-articular osteopenia, and 5) joint space narrowing, while for the latter, analysis focused on 1) the configuration of intra-articular bodies, 2) bone erosion, 3) synovial thickening, 4) conglomeration of intra-articular bodies, and 5) extra-articular extension. RESULTS: At hip radiography, juxta-articular calcified and/ or ossified bodies were seen in 12 of the 15 patients (80%), bone erosion in eight (53%), osteophytes in seven (47%), juxta-articular osteopenia in five (33%) and joint space narrowing in five (33%). In eight patients (53%), MR imaging depicted intra-articular bodies of focal low signal intensity at all pulse sequences, and areas of isointensity at T1WI and hyperintensity at T2WI. In three (20%), intra-articular bodies of focal low signal intensity and areas of hyperintensity at all pulse sequences were observed, with areas of iso-intensity at T1WI and hyperintensity at T2WI, while in four (27%), intra-articular bodies of only focal low signal intensity at all pulse sequences were apparent. Synovial thickening was present in 13 patients (87%), bone erosion in 11 (73%), conglomeration of the intra-articular bodies in 11 (73%), and an extra-articular herniation sac in six (40%). CONCLUSION: The most common radiographic finding of synovial osteochondromatosis of the hip was the presence of juxta-articular calcified and/ or ossified bodies. MR imaging depicted intra-articular bodies of focal low signal intensity at all pulse sequences, with areas of iso-intensity at T1WI and hyperintensity at T2WI. In addition, the presence of an extra-articular herniation sac was not uncommon.

Adult↗

PubMedDate not supplied

Overlapping ablation using a coaxial radiofrequency electrode and multiple cannulae system: experimental study in ex-vivo bovine liver.

OBJECTIVE: To assess the sizes and configurations of thermal zones after overlapping ablations using a coaxial radiofrequency (RF) electrode and multiple cannulae in ex-vivo bovine liver. MATERIALS AND METHODS: For ablation procedures, a coaxial RF electrode and introducer set was used. Employing real-time ultrasound guidance and overlapping techniques in explanted, fresh bovine liver, we created five kinds of thermal zones with one (n=10), two (n=8), four (n=3), and six ablation spheres (n=3). Following ablation, MR images were obtained and the dimensions of all thermal zones were measured on the longitudinal or transverse section of specimens. The shape of the composite ablation zones was evaluated using three-dimensional MR image reconstruction. RESULTS: At gross pathologic examination of ten single-ablation zones (spheres), the long-axis (transverse) and short-axis lengths of zones ranged from 3.7 to 4.4 (mean, 4.1) cm and from 3.5 to 4.0 (mean, 3.7) cm, respectively. The long-axis (transverse) and short-axis lengths of double-ablation zones (cylinders) with 23% overlap ranged from 7.0 to 7.7 (mean, 7.3) cm and from 3.0 to 3.9 (mean, 3.5) cm, respectively; those with 58% overlap ranged from 6.0 to 6.4 (mean, 6.2) cm and from 3.8 to 4.6 (mean, 4.3) cm, respectively. The long-axis (diagonal) and short-axis lengths on a transverse section of four-ablation zones (cakes) ranged from 8.5 to 9.7 (mean, 9.1) cm and from 3.0 to 4.1 (mean, 3.7) cm, respectively. Gross pathologic examination of three composite six-ablation zones (spheres) showed that the long-axis (diagonal) and short-axis lengths of zones ranged from 9.0 to 9.9 (mean, 9.4) cm and from 6.8 to 7.5 (mean, 7.2) cm, respectively. T2-weighted MR images depicted low-signal thermal zones containing multiple curvilinear and spotty regions of hyperintensity. CONCLUSION: Using a coaxial RF electrode and multiple cannulae, together with ultrasound guidance and precise overlapping ablation techniques, we successfully created predictable thermal zones in ex-vivo bovine liver.

Animals↗