• Journal of Veterinary Clinics
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• v.30 no.4
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• pp.320-323
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• 2013

Spinal cord infarction is becoming recognized as an important cause of acute myelopathy in cats. Although the definitive diagnosis is confirmed through postmortem histopathologic examination, MR imaging features provide valuable informations for the diagnosis of spinal cord infarction. The aim of this report is to describe MR findings of acute spinal cord infarction in two cats and to evaluate usefulness of low field MRI (0.3Tesla) as a potential diagnostic tool of acute spinal cord infarction. A cat (unknown age, neutered male mixed breed cat) was referred one day after the acute onset of non-ambulatory spastic tetraparesis and the other cat (a 9-year-old, neutered female domestic short hair cat) was presented due to the acute onset of non-ambulatory paraparesis and one day later paraplegia. The lesions of the MR images were shown on the spinal cord parenchyma over C2 to C6 in case 1 and L2 to L5 in case 2. The MR images in these two cases were characterized by focal intramedullary lesions, mainly involving grey matter which were hyperintense T2 weighted and FLAIR images and hyperintense on DWI and hypointense on ADC map. The MR findings in both cases were highly suggestive of acute spinal cord infarctions, based upon previous reported small animal cases and human cases. In conclusion, based on MR features, together with the history and clinical examination findings, MRI modality can be used as an antemortem tool for the diagnosis of acute spinal cord infarction in cats.

• The Korean Journal of Nuclear Medicine
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• v.37 no.4
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• pp.229-234
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• 2003

Purpose: Since the prognosis of measles encephalitis is poor, early diagnosis and proper management are very important to improve clinical outcomes. We compared Tc-99m ECD brain SPECT (SPECT) with MR imaging (MRI) for the detection of acute measles encephalitis. Materials and Methods: Eleven patients(M : F=4 : 7, age range 18 months-14 yrs) with acute measles encephalitis were enrolled in this studies. All of them underwent both MRI and SPECT. The results of SPECT were scored from 0 (normal) to 3 (most severe defect) according to perfusion state. We compared two image modalities for the detection of brain abnormality in acute measles encephalitis. Results: Seven of 11 patients (63.6%) revealed high signal intensity in the white matter on T2WI of MRI, on the other hand all patients (100%) showed hypoperfusion on SPECT. Severe perfusion deficits above score 2 were located with decreasing frequencies in the frontal lobe (81.8%), temporal lobe (72.7%), occipital lobe (27.3%), basal ganglia (27.3%), and parietal lobe (9.1%). Conclusion: We conclude that SPECT is more useful than MRI for the detection of brain involvement in patients with acute measles encephalitis.

• Journal of the Korean Society of Radiology
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• v.10 no.4
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• pp.279-284
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• 2016

Single-shot echo planar imaging(SS-EPI) is well established as high sensitivity for ischemic stroke. However, it is prone to susceptibility artifact in brain stem that diminish the image quality. single-shot turbo spin echo(SS-TSE) is a new DWI technique that can reduce susceptibility artifact. Thus, this research was conducted so as to reduce geometric distortion in brain stem by using single-shot turbo spin echo technique. Thirty patients without brain disease underwent diffusion MR on a 3T scanner with SS-EPI and SS-TSE. Obtained images with both sequences were analyzed for geometric distortion and error percentage as well. Image quality in terms of geometric distortion of SS-TSE were found to be significantly better than those for SS-EPI. And error percentage was considerably reduced for 2.4% of b0 image(from 11.1% to 8.7%), 1.2% of b1000 image(from 11.4% to 10.1%), respectively. In summary, diffusion MR using SS-TSE significantly reduce geometric distortion compared to SS-EPI in brain stem and may provide improved diagnostic performance.

• Investigative Magnetic Resonance Imaging
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• v.9 no.1
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• pp.30-35
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• 2005

Purpose : The purpose of this study is to observe the blood oxygen level dependent (BOLD) contrast changes due to the reaction of human brain at a gustatory sense in response to a salty-taste stimulation. Materials and Methods : Twelve healthy, non-smoking, right-handed male subjects (mean age: 25.6, range: 23-28 years) participated in this salty-taste stimulus functional magnetic resonance (fMRI) study. MRI scans were performed with 1.57 GE Signa, using a multi-slice GE-EPI sequence according to a blood-oxy-gen-level dependent (BOLD) experiment paradigm. Scan parameters included matrix size $128\times128$, FOV 250 mm, TR 5000 msec, TE 60 msec, TH/GAP 5/2 mm. Sequential data acquisitions were carried out for 42 measurements with a repetition time of 5 sec for each taste-stimulus experiments. Analysis of fMRI data was carried out using SPM99 implemented in Matlab. NaCl solution $(3\%)$ was used as a salty stimulus. The task paradigm consisted of alternating rest-stimulus cycles (30-second rest, 15-second stimulus) for 210 seconds. During the stimulus period, NaCl-solution was presented to the subject's mouth through plastic tubes as a bolus of delivered every 5 sec using -processor controlled auto-syringe pump. Results : Insula, frontal opercular taste cortex, amygdala and orbitofrontal cortex (OFC) were activated by a salty-taste stimulation $(NaCl,\;3\%)$ in the fMRI experiments. And dosolateral prefrontal cortex (DLPFC) was also significantly responded to salty-taste stimuli. Activation areas of the right side hemisphere were more superior to the left side hemisphere. Conclusion : The results of this study well correspond to the fact that both insula, amygdala, OFC, DLPFC areas are established as taste cortical areas by neuronal recordings in primates. Authors found that laboratory-developed auto-syringe pump is suitable for gustatory fMRI study. Further research in this field will accelerate to inquire into the mechanism of higher order gustatory process.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.114-118
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• 1997

Purpose: Functional MR imaging is the method of demonstrating changes in regional cerebral blood flow produced by sensory, motor, and any other tasks. Functional MR of visual cortex is performed as a patient stares a photic stimulation, so adaptable photic stimulation is necessary. The purpose of this study is to evaluate whether the size of photic stimulator can affect the degree of visual cortex activation. Materials and Methods: Functional MR imaging was performed in 5 volunteers with normal visual acuity. Photic stimulator was made by 39 light-emitting diodes on a plate, operating at 8Hz. The sizes of photic stimulator were full field, half field and focal central field. The MR imager was Siemens 1.5-T Magnetom Vision system, using standard head coil. Functional MRI utilized EPI sequence (TR/TE= 1.0/51. Omsec, matrix $No.=98{\times}128$, slice thickness=8mm) with 3sets of 6 imaging during stimulation and 6 imaging during rest, all 36 scannings were obtained. Activation images were obtained using postprocessing software(statistical analysis by Z-score), and these images were combined with T-1 weighted anatomical images. The activated signals were quantified by numbering the activated pixels, and activation a index was obtained by dividing the pixel number of each stimulator size with the sum of the pixel number of 3 study using 3 kinds of stimulators. The correlation between the activation index and the stimulator size was analysed. Results: Mean increase of signal intensities on the activation area using full field photic stimulator was about 9.6%. The activation index was greatest on full field, second on half field and smallest on focal central field in 4. The index of half field was greater than that of full field in 1. The ranges of activation index were full field 43-73%(mean 55%), half field 22-40 %(mean 32%), and focal central field 5-24%(mean 13%). Conclusion: The degree of visual cortex activation increases with the size of photic stimulator.

• Journal of the Korean Society of Radiology
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• v.12 no.5
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• pp.699-706
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• 2018

In this study, we measured signal intensities according to array coil position changes to provide reference data of coil directions and the distances as it deters image quality unless the coils are aligned properly. The multi-purpose MRI phantom was placed in body array coils, and it was moved to the top, bottom, left, and right directions by 2 cm from the center to 10 cm. After obtaining images, signal intensities were measured and compared. The results of this study were as follows: Except for the upward direction, the signal intensities of the reference signal was not significantly different from that of the reference signal intensity within 2cm in both T1 and T2-weighted images. In conclusion, in clinical circumstances which various challenges exist to align the coils exactly on the same lines, array coils should be positioned at least within 2 cm from the center except for the upward direction, on the same line to prevent the image qualities are lowered.

• Journal of Intelligence and Information Systems
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• v.11 no.1
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• pp.17-33
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• 2005

This paper presents the proposed a classifier of liver cirrhotic step using MR(magnetic resonance) imaging and hierarchical neural network. The data sets for classification of each stage, which were normal, 1type, 2type and 3type, were analysis in the number of data was 231. We extracted liver region and nodule region from T1-weight MR liver image. Then objective interpretation classifier of liver cirrhotic steps. Liver cirrhosis classifier implemented using hierarchical neural network which gray-level analysis and texture feature descriptors to distinguish normal liver and 3 types of liver cirrhosis. Then proposed Neural network classifier learned through error back-propagation algorithm. A classifying result shows that recognition rate of normal is $100\%$, 1type is $82.8\%$, 2type is $87.1\%$, 3type is $84.2\%$. The recognition ratio very high, when compared between the result of obtained quantified data to that of doctors decision data and neural network classifier value. If enough data is offered and other parameter is considered this paper according to we expected that neural network as well as human experts and could be useful as clinical decision support tool for liver cirrhosis patients.

• Clinical and Experimental Pediatrics
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• v.51 no.12
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• pp.1342-1345
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• 2008

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare white matter disorder, first described in the early 1990s. The brain in patients with MLC appears swollen on MRI, with diffuse white matter abnormalities; in addition, there is an invariable presence of subcortical cysts, primarily in the anterior temporal region sparing the deep white matter, basal ganglia, thalami, and cerebellum. Patients with MLC present with macrocephaly and neurological abnormalities such as motor deterioration, ataxia, spasticity, and cognitive deficits. We report a twenty-month-old boy who presented with seizures and macrocephaly, delay in development, and abnormal brain MRI findings compatible with the diagnosis of MLC. The brain MRI revealed bilateral hypersignal intense subcortical white matter regions in the frontal, temporal, and parietal lobes on T2-weighted images, which were not yet associated with cystic changes. During follow-up, the frequency of seizures decreased after anticonvulsant medication was started, but the head circumference remained above the 97th percentile, and the patient continued to have developmental delay.

• Journal of Yeungnam Medical Science
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• v.26 no.1
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• pp.30-37
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• 2009

Purpose : To radiologically differentiate renal oncocytoma from other renal solid tumors, we analyzed and characterized, retrogradely, radiologic findings of renal oncocytomas. Materials and Methods : Radiologic findings of pathologically proven renal oncocytoma were analyzed in 9 patients. CT was performed in all patients, ultrasonography in 4 patients and MRI in 3 patients.(51) Results : On ultrasonography, the echogenicity of the mass was slightly more hyperechoic than normal renal parenchyma in all 4 cases. Two cases were homogeneous and the remaining two cases were relatively homogeneous. On CT, all 8 cases showed iso-density to slightly low density compared to normal renal parenchyma and 5 cases were homogeneous but the central portion of the mass was of a slightly lower density than the peripheral portion in 3 cases. All six cases had an arterial phase scan and were heterogeneously enhanced. An irregular, lower-enhancing portion was found in the central portion of the mass. Segmental inversion of contrast enhancement was found in 5 of 6 cases that had a dynamic enhancement study. On MR T1-weighted imaging, the mass was of iso-signal intensity to normal renal parenchyma and the central portion of the mass had a slightly hypo-signal intensity than the peripheral portion. On T2-weighted imaging, 2 cases were heterogeneous; the peripheral portion was of low signal intensity and central portion was of higher signal intensity than normal renal parenchyma. One case was relatively homogeneous and showed a slightly lower signal intensity than that of normal parenchyma, except for a central small portion showing high signal intensity. For 2 cases that had a dynamic study, a segmental inversion of contrast enhancement was noted. Conclusion : Renal oncocytoma is seen as a well-marginated solid mass lesion. On enhanced scans it is heterogeneously enhanced and segmental inversion of contrast enhancement may be seen. The possibility of oncocytoma can be suggested in cases showing these radiologic findings.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.119-124
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• 1997

Purpose: To assess the utility of magnetic resonance(MR) cerebral blood volume (CBV) map in the evaluation of brain tumors. Materials and Methods: We performed perfusion MR imaing preoperatively in the consecutive IS patients with intracranial masses(3 meningiomas, 2 glioblastoma multiformes, 3 low grade gliomas, 1 lymphoma, 1 germinoma, 1 neurocytoma, 1 metastasis, 2 abscesses, 1 radionecrosis). The average age of the patients was 42 years (22yr -68yr), composed of 10 males and S females. All MR images were obtained at l.ST imager(Signa, CE Medical Systems, Milwaukee, Wisconsin). The regional CBV map was obtained on the theoretical basis of susceptibility difference induced by first pass circulation of contrast media. (contrast media: IScc of gadopentate dimeglumine, about 2ml/sec by hand, starting at 10 second after first baseline scan). For each patient, a total of 480 images (6 slices, 80 images/slice in 160 sec) were obtained by using gradient echo(CE) single shot echo-planar image(EPI) sequence (TR 2000ms, TE SOms, flip angle $90^{\circ}$, FOV $240{\times}240mm,{\;}matrix{\;}128{\times}128$, slice-thick/gap S/2.S). After data collection, the raw data were transferred to CE workstation and rCBV maps were generated from the numerical integration of ${\Delta}R2^{*} on a voxel by voxel basis, with home made software (${\Delta}R2^{*}=-ln (S/SO)/TE). For easy visual interpretation, relative RCB color coding with reference to the normal white matter was applied and color rCBV maps were obtained. The findings of perfusion MR image were retrospectively correlated with Cd-enhanced images with focus on the degree and extent of perfusion and contrast enhancement. Results: Two cases of glioblastoma multiforme with rim enhancement on Cd-enhanced Tl weighted image showed increased perfusion in the peripheral rim and decreased perfusion in the central necrosis portion. The low grade gliomas appeared as a low perfusion area with poorly defined margin. In 2 cases of brain abscess, the degree of perfusion was similar to that of the normal white matter in the peripheral enhancing rim and was low in the central portion. All meningiomas showed diffuse homogeneous increased perfusion of moderate or high degree. One each of lymphoma and germinoma showed homogenously decreased perfusion with well defined margin. The central neurocytoma showed multifocal increased perfusion areas of moderate or high degree. A few nodules of the multiple metastasis showed increased perfusion of moderate degree. One radionecrosis revealed multiple foci of increased perfusion within the area of decreased perfusion. Conclusion: The rCBV map appears to correlate well with the perfusion state of brain tumor, and may be helpful in discrimination between low grade and high grade gliomas. The further study is needed to clarify the role of perfusion MR image in the evaluation of brain tumor.