• Journal of the Korean Society of Radiology
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• v.82 no.4
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• pp.1005-1010
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• 2021

We report a case of Immunoglobulin G4 (IgG4) related disease involving the pterygoplataine fossa. A 83-year-old male presented with left ocular pain and visual disturbance. CT showed an isodense soft tissue lesion in the left pterygopalatine fossa with bony sclerotic changes and erosion. MRI revealed an infiltrative soft tissue mass in the left pterygopalatine fossa as a T2 slightly low signal intensity and heterogeneous enhancement. The patient underwent left ethmoidectomy, and biopsy of the mass was conducted. The histopathological diagnosis was IgG4-related disease. In this case, it was difficult to differentiate invasive aspergillosis, which is common in immunocompromised patients, considering the patient's clinical history of diabetes mellitus. This report describes the imaging findings of IgG4-related disease mimicking invasive sinusitis such as invasive aspergillosis.

• Investigative Magnetic Resonance Imaging
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• v.18 no.1
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• pp.17-24
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• 2014

Purpose : To determine whether high-resolution contrast-enhanced three dimensional imaging with spoiled gradient-recalled sequence (HR-CE 3D-SPGR) plays a meaningful role in the assessment of intracranial vertebral artery (ICVA) and posterior inferior cerebellar artery (PICA) in lateral medullary infarction (LMI). Materials and Methods: Twenty-five patients confirmed with LMI were retrospectively enrolled with approval by the IRB of our institute, and 3T MRI with HR-CE 3D-SPGR and contrast-enhanced magnetic resonance angiography (CE-MRA) were performed. Two radiologists who were blinded to clinical information and other brain MR images including diffusion weighted image independently evaluated arterial lesions in ICVA and PICA. The demographic characteristics, the area of LMI and cerebellar involvement were analyzed and compared between patients with arterial lesion in ICVA only and patients with arterial lesions in both ICVA and PICA on HR-CE 3D-SPGR. Results: Twenty-two of twenty-five LMI patients had arterial lesions in ICVA or PICA on HR-CE 3D SPGR. However twelve arterial lesions in PICA were not shown on CE-MRA. Concurrent cerebellar involvement appeared more in LMI patients with arterial lesion in ICVA and PICA than those with arterial lesion in ICVA alone (p = 0.069). Conclusion: HR-CE 3D-SPGR can help evaluate arterial lesions in ICVA and PICA for LMI patients.

• Journal of Korea Multimedia Society
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• v.19 no.2
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• pp.375-385
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• 2016

Recently, several implantable hearing aids such as cochlear implant, middle ear implant, etc., which have a module receiving power and signal from outside the body, are frequently used to treat the hearing impaired patients. Most of implantable hearing aids are adopted permanent magnet pairs to couple between internal and external devices for the enhancement of power transmission. Generally, the internal device which containing the magnet in the center of receiving coil is implanted under the skin of human temporal bone. In case of MRI scanning of a patient with the implantable hearing aid, however, homogeneous magnetic fields of the MRI might be interfered by the implanted magnet. For the above reasons, the MR image is degraded by large area of artifact, so that diagnostics are almost impossible in deteriorated region. In this paper, we proposed an external coil system that can reduce the artifact of MR image due to the internal coupling magnet. By finite element analysis estimating area of MR artifact according to varying current and shape of the external coil, optimal coil parameters were extracted. Finally, the effectiveness of the proposed external coil system was verified by confirming the artifact at real MRI scan.

• Journal of Veterinary Clinics
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• v.24 no.1
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• pp.26-28
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• 2007

An 11-year-old castrated male, Shih-tzu dog was admitted for progressive weight-bearing lameness and mass on the right hindlimb. Radiography and ultrasonography revealed a large well-marginated multinodular mass with mixed echogenicity. On T1 and T2-weighted magnetic resonance imaging (MRI), the mass has a heterogenous signal intensity similar to or higher than muscle. The masses were extended to the pelvic cavi쇼 through obturator foramen and displaced the rectum dorsally. It was diagnosed as synovial sarcoma which was composed with mesenchymal and epithelial elements on histopathological findings of the multifocal biopsied specimen. MRI was helpful to determine the definitive margin for surgical resection of the mass. The mass was recurred at the 6th month after surgery. On the 10th month, the patient was euthanasiuzed by owner's request.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.121-127
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• 2007

Muscle force produced by muscle fibers is transmitted to bones via tendinous structures(aponeuroses and tendon), resulting in joint(s) movement. As force-transmitting elements, mechanical behavior of aponeuroses and tendon are closely related with the function of muscle-tendon complex. The purpose of this study was to determine strain characteristics of aponeuroses for in-vivo human soleus muscle during submaximal voluntary contractions using an advanced medical imaging technique, velocity-encoded phase-contrast magnetic resonance imaging (VE-PC MRI). VE-PC MRI of the soleus muscle-tendon complex was acquired during submaximal isometric plantarflexion contraction-relaxation cycle (n = 7), using 3.0T Trio MRI scanner(Siemens AG, Malvern, MA). From the VE-PC MRI containing the tissue velocity in superior-inferior direction, twenty regions of interest(20 ROI; 10 on the anterior aponeurosis and 10 on the posterior aponeurosis) were tracked. During the isometric plantarflexion contraction-relaxation cycle, velocity and displacement profiles were different between the anterior and posterior aponeuroses, indicating heterogeneous strain behavior along the length of the leg. The anterior aponeurosis elongated while the posterior aponeurosis shortened during the initial phase of the contraction. Moreover, strain behavior of the posterior aponeurosis was different from that of the Achilles tendon. Possible explanation for the observed variations in strain behavior of aponeuroses was investigated with morphological assessment of the soleus muscle and it was found that the intramuscular tendinous structures significantly vary among subjects. In conclusion, the heterogeneous mechanical behavior of the soleus aponeuroses and the Achilles tendon suggests that the complexity of skeletal muscle-tendon complex should be taken into consideration when modeling the complex for better understanding of its functions.

• Investigative Magnetic Resonance Imaging
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• v.17 no.3
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• pp.181-191
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• 2013

Purpose : To evaluate the usefulness of in vivo magnetic resonance (MR) imaging for tracking intravenously injected superparamagnetic iron oxide (SPIO)-labeled human umbilical vein endothelial cells (HUVECs) in an acute renal failure (ARF) rat model. Materials and Methods: HUVECs were labeled with SPIO and poly-L-lysine (PLL) complex. Relaxation rates at 1.5-T MR, cell viability, and labeling stability were assessed. HUVECs were injected into the tail vein of ARF rats (labeled cells in 10 rats, unlabeled cells in 2 rats). Follow-up serial $T2^*$-weighted gradient-echo MR imaging was performed at 1, 3, 5 and 7 days after injection, and the MR findings were compared with histologic findings. Results: There was an average of $98.4{\pm}2.4%$ Prussian blue stain-positive cells after labeling with SPIOPLL complex. Relaxation rates ($R2^*$) of all cultured HUVECs at day 3 and 5 were not markedly decreased compared with that at day 1. The stability of SPIO in HUVECs was maintained during the proliferation of HUVECs in culture media. In the presence of left unilateral renal artery ischemia, $T2^*$-weighted MR imaging performed 1 day after the intravenous injection of labeled HUVECs revealed a significant signal intensity (SI) loss exclusively in the left renal outer medulla regions, but not in the right kidney. The MR imaging findings at days 3, 5 and 7 after intravenous injection of HUVECs showed a SI loss in the outer medulla regions of the ischemically injured kidney, but the SI progressively recovered with time and the right kidney did not have a significant change in SI in the same period. Upon histologic analysis, the SI loss on MR images was correspondent to the presence of Prussian blue stained cells, primarily in the renal outer medulla. Conclusion: MR imaging appears to be useful for in vivo monitoring of intravenously injected SPIO-labeled HUVECs in an ischemically injured rat kidney.

• 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.

• Journal of the Korean Orthopaedic Association
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• v.54 no.5
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• pp.418-426
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• 2019

Purpose: This study analyzed the features of humeral head decentralization in large to massive rotator cuff tears with a shoulder dislocation in the elderly. Moreover, shoulder instability and treatment were reviewed. Materials and Methods: From May 2005 to February 2017, Group A containing 45 cases (45 patients) over 65 years old accompanied by a large or massive rotator cuff tear with a shoulder dislocation and Group B containing 45 cases (45 patients) without a shoulder dislocation were enrolled. The mean ages in Groups A and B were 73.2 and 72.1 years old, and the mean follow-up periods were 30.7 and 31.3 months, respectively. Twenty-one cases (46.7%) in Group A underwent rotator cuff repair, and 8 cases (17.8%) underwent concomitant rotator cuff repair with Bankart repair. Sixteen cases (35.6%) underwent reverse total shoulder arthroplasty for cuff tear arthropathy. 45 cases (100%) in Group B underwent rotator cuff repair. The off-the center and head elevation were measured in the preoperative magnetic resonance imaging (MRI) of Groups A and B. The preoperative and postoperative visual analogue scale (VAS) score, American Shoulder and Elbow Surgeons (ASES) score, and University of California Los Angeles (UCLA) score in Groups A and B were compared. Results: In Groups A and B, the mean off-the centers were posterior 7.41 mm and posterior 2.02 mm (p=0.03), and the mean head elevations were superior 6.66 mm and superior 2.44 mm (p=0.02), respectively. The mean ASES scores of Groups A and B were 32.8 and 33.4 before surgery, and 77.1 (p=0.02) and 78.1 (p=0.02) after surgery (p=0.18), respectively. The mean UCLA scores of Groups A and B were 13.1 and 12.8 before surgery, and 28.9 (p=0.02) and 29.5 (p=0.01) after surgery (p=0.15), respectively. Conclusion: Patients over 65 years old with a shoulder dislocation in large to massive rotator cuff tears had higher off-the center and head elevation on the preoperative MRI than those without a shoulder dislocation. This measurement can help predict preceding shoulder instability. Early rotator cuff repairs should be performed and other treatments, such as Bankart repair and reverse total shoulder arthroplasty, should also be considered.

• Investigative Magnetic Resonance Imaging
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• v.8 no.1
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• pp.1-8
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• 2004

Purpose : Information about electrical activity inside the brain during fMRl scans is very useful in monitoring physiological function of the patient or locating the spatial position of the activated region in the brain. However, many additional noises appear in the EEG signal acquired during the MRI scan. Gradient induced noise is the biggest one among the noises. In this work, we propose a gradient noise reduction method using the independent component analysis (ICA) method. Materials and Methods : We used a 29-channel MR-compatible EEG measurement system and a 3.0 Tesla MRI system. We measured EEG signals on a subject lying inside the magnet during EPI scans. We selectively removed the gradient noise from the measured EEG signal using the ICA method. We compared the results with the ones obtained with conventional averaging method and PCA method. Results : All the noise reduction methods including the averaging and PCA methods were effective in removing the noise in some extent. However, the proposed ICA method was found to be superior to the other methods. Conclusion : Gradient noise in EEG signals acquired during fMRI scans can be effectively reduced by the ICA method. The noise-reduced EEG signal can be used in fMRI studies of epileptic patients or combinatory studies of fMRI and EEG.

• Journal of Biomedical Engineering Research
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• v.25 no.1
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• pp.43-47
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• 2004

Interests in human brain functionality and its connectivity have much frown up. DTI (Diffusion tensor imaging) has been known as a non-invasive MR) technique capable of providing information on water diffusion in tissues and the organization of white matter tract. Thus. It can provide us the information on the direction of brain fiber tract and the connectivity among many important cortical regions which can not be examined by other anatomical or functional MRI techniques. In this study. was used the 24 bit color coding scheme on the IDL platform in the windows environment to visualize the orientation of major fiber tracts of brain such as main association, projection, commissural fibers and corticospinal tracts. We additionally implemented a color coding scheme for each directional component and FA (fractional anisotropy), and used various color tables for them to be visualized more definitely. Consequently we implemented a fancy and basic technique to visualize the directional information of fiber tracts efficiently and we confirmed the feasibility of the 24 bit color coding scheme in DTI by visualizing main fiber tracts.