• The Journal of Korean Orthopaedic Ultrasound Society
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• v.3 no.2
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• pp.79-83
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• 2010

Musculoskeletal ultrasonography has been used as a convenient and simple tool for diagnosis of various conditions of orthopaedic diseases for many years. Generally magnetic resonance imaging (MRI) is thought to be the best method to search for anatomical structures or variations. However, for dynamic conditions such as dislocation or subluxation of tendons and nerves, MRI is not superior to ultrasonography, especially dynamic ultrasonography. So we present such a patient with an ulnar nerve subluxation at the elbow who has symtoms mimicking cubital tunnel syndrome diagnosed by dynamic ultrasonography and treated successfully by ulnar nerve anterior transposition and think that dynamic ultrasonography is a useful method for diagnosing dynamic condition such as ulnar nerve subluxation mimicking cubital tunnel syndrome.

• Korean Journal of Radiology
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• v.22 no.7
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• pp.1021-1033
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• 2021

Objective: To assess the expression of vascular normalization genes in different molecular subtypes of breast cancer and to determine whether molecular subtypes with a higher vascular normalization gene expression can be identified using dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI). Materials and Methods: This prospective study evaluated 306 female (mean age ± standard deviation, 50 ± 10 years), recruited between January 2014 and August 2017, who had de novo breast cancer larger than 1 cm in diameter (308 tumors). DCE MRI followed by IVIM DWI studies using 11 different b-values (0 to 1200 s/mm²) were performed on a 1.5T MRI system. The Tofts model and segmented biexponential IVIM analysis were used. For each tumor, the molecular subtype (according to six [I-VI] subtypes and PAM50 subtypes), expression profile of genes for vascular normalization, pericytes, and normal vascular signatures were determined using freshly frozen tissue. Statistical associations between imaging parameters and molecular subtypes were examined using logistic regression or linear regression with a significance level of p = 0.05. Results: Breast cancer subtypes III and VI and PAM50 subtypes luminal A and normal-like exhibited a higher expression of genes for vascular normalization, pericyte markers, and normal vessel function signature (p < 0.001 for all) compared to other subtypes. Subtypes III and VI and PAM50 subtypes luminal A and normal-like, versus the remaining subtypes, showed significant associations with K^trans, k_ep, v_p, and IAUGC_BN90 on DEC MRI, with relatively smaller values in the former. The subtype grouping was significantly associated with D, with relatively less restricted diffusion in subtypes III and VI and PAM50 subtypes luminal A and normal-like. Conclusion: DCE MRI and IVIM parameters may identify molecular subtypes of breast cancers with a different vascular normalization gene expression.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.96-96
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• 2002

목적： MRI 시스템의 비약적인 발전으로 인하여, 시스템에서 발생되는 noise가 상당히 줄었다. 따라서 시스템에서 발생되는 random noise뿐만 아니라 sampling 과정에서 발생되는 quantization noise도 중요하게 고려하여야 할 요소가 되었다. 특히, MRI 신호의 경우 dynamic range가 크기 때문에 bit 수가 큰 ADC를 이용하여 데이터를 얻어야 한다. 그러나, bit 수가 크고 높은 sampling rate를 갖는 ADC의 경우 가격이 높을 뿐만 아니라, 기존의 장비를 교체해야하는 어려움이 있다. 본 연구는 oversampling과 quantization noise와의 관계를 컴퓨터 시뮬레이션을 통하여 알아보고, MRI영상에서 oversampling을 통하여 quantization noise를 줄임으로써 영상의 질을 개선하고자 한다.

• Journal of Korean Neurosurgical Society
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• v.42 no.1
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• pp.27-34
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• 2007

Objective : On the magnetic resonance image (MRI) of the infiltrating brain tumor, enhancement is usually higher in malignant tumor than in benign tumor, and tumor cells can invade into the peritumoral area without definite enhancement. In various pathological conditions, the blood brain barrier (BBB) becomes changed to pathological condition, allowing various materials extravasating into the interstitial space, and degree of enhancement is depend on the pathology. Authors performed dynamic MRI on enhancing and surrounding edematous area in order to evaluate the degrees of opening of BBB, to differentiate tumor from non-tumorous condition, and to determine its relationship with the recurrence of the tumor. Methods : Dynamic MRI was performed in 25 patients. Dynamic scans were done every 15 seconds after administration of Gd-DTPA on the enhancing and surrounding area for maximum 300 seconds, and the patterns of enhancement were ana lysed. The enhancement curve with initial steep increase followed by slow decrease was defined as "N pattern", those with initial steep increase followed by additional slow increase as "T pattern", and those with initial steep increase followed by plateau as "E pattern". Histopathological findings were compared with the dynamic scan. Results : The graphs taken from enhancing area showed "T pattern" regardless of pathology. In the surrounding area, "T pattern" was noticed in the malignant tumors, but "E pattern" or "N pattern" was noted in low-grade or benign tumors and non-tumorous condition. "T pattern" in the surrounding area was related to the malignant with tumor cell infiltration and recurrence. Conclusion : The results suggest that the malignant tumor infiltration changes the condition of BBB enough to extravasate the Gd-DTPA. Enhancement pattern in the surrounding edematous area may be a useful information to differentiate the malignant glioma with the low-grade and benign tumors or other non-tumorous conditions.

• 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.18 no.1
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• pp.25-33
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• 2014

Purpose : To investigate whether quantitative parameters derived from Diffusion-weighted magnetic resonance imaging (DW-MRI) correlate with those of Dynamic contrast-enhanced MRI (DCE-MRI). Materials and Methods: Thirteen patients with pathologically or clinically proven bony metastasis who had undergone MRI prior to treatment were included. The voxel size was $1.367{\times}1.367{\times}5mm$. A dominant tumor was selected and the apparent diffusion coefficient (ADC) value and DCE-MRI parameters were obtained by matching voxels. DCE-MRI data were analyzed yielding estimates of $K^{trans}$ (volume transfer constant) and $v_e$. (extravascular extracellular volume fraction). Statistical analysis of ADC, $K^{trans}$, and $v_e$ value was conducted using Pearson correlation analyses. Results: Fifteen lesions in pelvic bones were evaluated. Of these, 11 showed a statistically significant correlation (P<0.05) between ADC and $K^{trans}$. The ADC and $K^{trans}$ were inversely related in 7 lesions and positively related in 4 lesions. This did not depend on the primary cancer or site of metastasis. The ADC and $v_e$ of 9 lesions correlated significantly. Of these, 4 lesions were inversely related and 5 lesions were positively related. Conclusion: Unlike our theoretic hypothesis, there was no consistent correlation between ADC values and $K^{trans}$ or between ADC values and $v_e$ in metastatic bone tumors.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.817-818
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• 2006

In Magnetic Resonance Imaging(MRI), the QRS complex of ECG is used as a trigger signal for MRI scan. But, gradient and RF(radio frequency) artifacts which are caused to static and dynamic field in MRI scanner cause interference in the ECG. Also, the signal shape of theses artifacts can be similar to the QRS-complex, causing possible misinterpretation during patient monitoring and false gating of the MRI. In case of using general FIR or IIR band-pass filters for minimizing the artifacts, artifact-reduction-ratio is not excellent. So, an adaptive real-time digital filter is proposed for reduction of noise by gradient and RF(radio frequency) artifacts. The proposed filter for MRI-Gating is based on the noise-canceller with NLMS(Normalized Least Mean Square) algorithm. The reference signals of the adaptive noise canceller are a combination of the noisy three channel ECG signals. In conclusions, the proposed method showed the acceptable quality of ECG signal with sufficient SNR for gating the MRI and possibility of real time implementation.

• Annals of Clinical Neurophysiology
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• v.4 no.1
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• pp.38-43
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• 2002

Background & Purpose : Dynamic susceptibility contrast MR imaging, one method of perfusion MRI, was developed to define cerebral hemodynamic status with good anatomical resolution. The authors investigated hemodynamic parameters using this imaging method, in an effort to identify hemodynamic changes on the remote crossed cerebellum of patients with a supratentorial infarct. Methods : Dynamic susceptibility contrast MR imaging was performed in 15 patients with only unilateral supratentorial infarcts. Imaging was obtained at the anatomic level of the cerebellum. rCBF, rCBV, MTT and TP were determined over both cerebellar hemispheres of interest. Results : The rCBF and rCBV values of the contralateral cerebellar hemisphere were significantly more decreased than those of the ipsilateral cerebellar hemisphere in 12 patients(p=0.028, 0.033). MTT and TP values of the contralateral and ipsilateral cerebellar hemispheres didn't reveal any differences(p=0.130, 0.121). Conclusions : The results of this work suggest that the region which are remote from the ischemic brain lesion shows no changes of MTT or TP but show decrease of rCBF and rCBV, mean to diaschisis, it also demonstrates that perfusion MRI is an easily available method to evaluate the hemodynamic status of the brain.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.18
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• pp.8335-8338
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• 2016

Purpose: To make a comparison of single voxel magnetic resonance spectroscopy (SV-MRS) and dynamic contrast enhancement (DCE) MRI for differentiation of benign and malignant breast lesions in a sample of Iranian women. Materials and Methods: A total of 30 women with abnormal breast lesions detected in mammography, ultrasound, or clinical breast exam were examined with DCE and SV-MRS. tCho (total choline) resonance in MRS spectra was qualitatively evaluated and detection of a visible tCho peak at 3.2 ppm was defined as a positive finding for malignancy. Different types of DCE curves were persistent (type 1), plateau (type 2), and washout (type 3). At first, lesions were classified according to choline findings and types of DCE curve, finally being compared to pathological results as the standard reference. Results: this study included 19 patients with malignant lesions and 11 patients with benign ones. While 63.6 % of benign lesions (7 of 11) showed type 1 DCE curves and 36.4% (4 of 11) showed type 2, 57.9% (11of 19) of malignant lesions were type 3 and 42.1% (8 of 19) type 2. Choline peaks were detected in 18 of 19 malignant lesions and in 3 of 11 benign counterparts. 1 malignant and 8 benign cases did not show any visible resonance at 3.2 ppm so SV-MRS featured 94.7% sensitivity, 72.7 % specificity and 86.7% accuracy.Conclusions: The present findings indicate that a combined approach using MRS and DCE MRI can improve the specificity of MRI for differentiation of benign and malignant breast lesions.

• Proceedings of the KSMRM Conference
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• 1999.04a
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• pp.123-129
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• 1999