• Journal of Veterinary Clinics
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• v.27 no.6
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• pp.755-759
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• 2010

A 6-year-old, intact female Dachshund was presented with generalized seizure for 2 days. Based on the neurologic and physical examinations, intracranial diseases were suspected. 1.5T and 7.0T magnetic resonance imaging (MRI) of the brain were taken. The MRI results revealed diffuse hyperintense lesions in the area of the diencephalon to the medulla oblongata in the T2-weighted images. Canine distemper virus-induced meningoencephalitis was confirmed by the result of RT-PCR of the cerebrospinal fluid (CSF). The dog was euthanized 7 days after diagnosis due to poor prognosis and clinical deterioration. Postmortem histopathologic examination was consistent with the MRI findings. This is the first case report using 1.5T and 7.0T MRI to compare the virus-induced intracranial lesions in meningoencephalitis.

• Investigative Magnetic Resonance Imaging
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• v.4 no.1
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• pp.14-19
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• 2000

Purpose : This study was to present the functional brain mapping of both functional magnetic resonance imaging(MRI) and transcranial magnetic stimulation(TMS) in a case of schizencephaly. Materials and methods : A 28-year-old man, who had left hemiplegia and schizencephaly in right cerebral hemisphere, was exacted with both functional MRI and TMS. Motor function of left hand was decreased whereas right hand was within normal limit. For functional MRI, gradient-echo echo planar imaging($TR/TE/{\alpha}$=1.2 sec/90 msec/90) was employed. The paradigm of motor task consisted of repetitive self-paseo hand flexion-extension exercises with 1-2 Hz periods. An image set of 10 slices was repetitively acquired with 15 seconds alternating periods of task performance and rest and total 6 cycles (three ON periods and three OFF periods) were performed. In brain mapping, TMS was performed with the round magnetic stimulator (mean diameter; 90mm). The magnetic stimulation was done with 80% of maximal output. The latency and amplitude of motor evoked potential(MEP)s were obtained from both abductor pollicis brevis(APB) muscles. Results : Functional MRI revealed activation of the left primary motor cortex with flexion-extension exercises of healthy right hand. On the other hand, the left primary motor cortex, left supplementary motor cortex, and left promoter areas were activated with flexion-extension exercises of left hand. In TMS, magnetic evoked potentials were induced in no areas of right cerebral hemisphere, but in 5 areas of left corebral hemisphere from both abductor pollicis brevis. Latency, amplitude, and contour of response of the magnetic evoked potentials in both hands were similar. Conclusion : Functional MRI and TMS in a patient with schizencephaly were successfully used to localize cortical motor function. Ipsilateral motor pathway is thought to be secondary to reinforcement of the corticospinal tract of the ipsilateral motor cortex.

• Investigative Magnetic Resonance Imaging
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• v.4 no.1
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• pp.1-6
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• 2000

Protocol이란 Dorland의 의학사전에 의하면 "어떤 술기의 절차에 대한 명백하고 상세한 계획서(an explicit detiled plan of a procedure)"로 정의된다. 그래서 liver MR imaging protocol은 간에 발생한 병적 문제를 해결하기 위해서, 자기공명 영상술을 실시하는 구체적이고 세부적인 지침서를 말하게 된다. 그러나 현실적으로 병원에 따라 imaging protocol은 조금씩 다르다. 왜냐하면 자기공명영상 장비가 다르고, 적절한 펄스파형(pulse sequence)에 대한 통일된 안이 없기 때문이다. 자기공명영상술은 지금도 계속해서 빠르게 발전하고 있기 때문에, 현재 통용되는 영상 술기에 대한 자세한 지침은 곧 소용이 없게 된다. 그래서 본 소고에서는 간의 자기공명영상화의 병변의 특성화에 대한 기본적인 면에 더욱 중점을 두고 기술하고자 한다.

• Investigative Magnetic Resonance Imaging
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• v.15 no.2
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• pp.91-101
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• 2011

Perfusion magnetic resonance imaging (pMRI) is a special technique for evaluation of blood flow. Exogenous pMRI methods which are dynamic susceptibility contrast (DSC) and dynamic contrast-enhanced (DCE) use an intravenous bolus injection of paramagnetic contrast agent. In contrast, an endogenous pMRM method which is arterial spin labeling (ASL) use diffusible blood in body. In order to scan pMRI in human, technical optimizations are very important according to disease conditions. For examples, DSC is popularly used in patients with acute stroke due to its short scan time, while DSC or DCE provides the various perfusion indices for patients with tumor. ASL is useful for children, women who are expected to be pregnant, and in patients with kidney diseases which are problematic in nephrogenic systemic fibrosis (NSF). Perfusion MRI does not require any injection of radioisotopes. We expect that demand for perfusion MRI will be higher in evaluating drug efficacy and other treatment effects.

• Investigative Magnetic Resonance Imaging
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• v.14 no.2
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• pp.121-125
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• 2010

Purpose : The purpose of this study was to evaluate the diagnostic accuracy of 3.0-T breast MRI for detecting additional breast cancer soon after the initial diagnosis of breast cancer. Materials and Methods : From March to June 2009, 101 patients recently diagnosed breast cancer underwent breast MRI and surgery. Parameters analyzed on MRI were total extent of tumor, suspicious findings of multifocal, multicentric, or contralateral cancer. The diagnosis of MRI-detected cancer was confirmed by means of biopsy or surgical specimen evaluation after the localization. Results : MRI showed 37 additional suspicious findings in 34 patients. Twenty nine findings were true-positive (29/37, 78.4%), including 16 cases of multifocality, 11 cases of multicentricity and 2 cases of contralateral cancer. Among these cancers, 13 (44.8%) were ductal carcinoma in situ (DCIS) and 16 (55.1%) were infiltrating cancer. Eight findings were false-positive (8/37, 21.6%) including 6 cases of benign disease and 2 cases of high-risk lesions. Conclusion : In women with recently diagnosed breast cancer, 3.0-T MR imaging showed additional suspicious findings in 33.7%. The sensitivity and specificity for detecting additional breast cancer was 100% and 89.3%, respectively.

• Journal of the Korean Society of Radiology
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• v.82 no.3
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• pp.654-669
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• 2021

Purpose To evaluate the accuracy of MRI in predicting the pathological complete response (pCR) and the residual tumor size of breast cancer after neoadjucant chemotherapy (NAC), and to determine the factors affecting the accuarcy. Materials and Methods Eighty-eight breast cancer patients who underwent surgery after NAC at our center between 2010 and 2017 were included in this study. pCR was defined as the absence of invasive cancer on pathological evaluation. The maximum diameter of the residual tumor on post-NAC MRI was compared with the tumor size of the surgical specimen measured pathologically. Statistical analysis was performed to elucidate the factors affecting pCR and the residual tumor size-discrepancy between the MRI and the pathological measurements. Results The pCR rate was 10%. The diagnostic accuracy of MRI and the area under the curve for predicting pCR were 90.91% and 0.8017, respectively. The residual tumor sizes obtained using MRI and pathological measurements showed a strong correlation (r = 0.9, p < 0.001), especially in patients with a single mass lesion (p = 0.047). The size discrepancy between MRI and the pathological measurements was significantly greater in patients with the luminal type (p = 0.023) and multifocal tumors/non-mass enhancement on pre-NAC MRI (p = 0.047). Conclusion MRI is an accurate tool for evaluating pCR and residual tumor size in breast cancer patients who receive NAC. Tumor subtype and initial MRI features affect the accuracy of MRI.

• Journal of the Korean Society of Radiology
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• v.6 no.6
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• pp.473-476
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• 2012

The PET-MRI which has been installed and being managed recently uses both magnetic field and radiation. Most radiation workers wear a thermoluminescenct dosimeter (TLD) as a personal radiation dosimeter, and the TLD is affected both by a magnetic field and radiation. In this research, the same amount of X-ray was applied to 36 TLDs, and the changes in the dose of the 32 TLDs exposed to magnetic field at the location where its intensity of the magnetic resonance imaging (MRI) was about 5000 Gauss for eight hours with one-hour unit and that of the four TLDs not exposed to magnetic field were compared and checked. The measurement result showed that exposure dose of the TLD attached to the MRI changed irregularly depending on the amount of exposure time. Therefore, the TLD whose amount of changes little in the environment of a MRI is demanded to be developed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.6
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• pp.490-496
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• 2014

The thickness of knee joint cartilage causes most diseases of knee. Therefore, an articular cartilage segmentation of knee magnetic resonance imaging (MRI) is required to diagnose a knee diagnosis correctly. In particular, fully automatic segmentation method of knee joint cartilage enables an effective diagnosis of knee disease. In this paper, we analyze a well-known level-set based segmentation method in brain MRI, and apply that method to knee MRI with solving some problems from different image characteristics. The proposed method, a fully automatic segmentation in whole process, enables to process faster than previous semi-automatic segmentation methods. Also it can make a three-dimension visualization which provides a specialist with an assistance for the diagnosis of knee disease. In addition, the proposed method provides more accurate results than the existing methods of articular cartilage segmentation in knee MRI through experiments.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.32-41
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• 1997

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.58-65
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• 1997