• Investigative Magnetic Resonance Imaging
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• 제23권1호
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• pp.1-16
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• 2019

Dynamic contrast enhanced (DCE) magnetic resonance (MR) imaging plays an important role in non-invasive detection and characterization of primary and metastatic lesions in the liver. Recently, efforts have been made to improve spatial and temporal resolution of DCE liver MRI for arterial phase imaging. Review of recent publications related to arterial phase imaging of the liver indicates that there exist primarily two approaches: breath-hold and free-breathing. For breath-hold imaging, acquiring multiple arterial phase images in a breath-hold is the preferred approach over conventional single-phase imaging. For free-breathing imaging, a combination of three-dimensional (3D) stack-of-stars golden-angle sampling and compressed sensing parallel imaging reconstruction is one of emerging techniques. Self-gating can be used to decrease respiratory motion artifact. This article introduces recent MRI technologies relevant to hepatic arterial phase imaging, including differential subsampling with Cartesian ordering (DISCO), golden-angle radial sparse parallel (GRASP), and X-D GRASP. This article also describes techniques related to dynamic 3D image reconstruction of the liver from golden-angle stack-of-stars data.

• 한국자기공명학회논문지
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• 제9권2호
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• pp.93-102
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• 2005

Purpose: To develop an advanced non-linear curve fitting (NLCF) algorithm for dynamic susceptibility contrast study of brain. Materials and Methods: The first pass effects give rise to spuriously high estimates of $K^{trans}$ in voxels with large vascular components. An explicit threshold value has been used to reject voxels. Results: By using this non-linear curve fitting algorithm, the blood perfusion and the volume estimation were accurately evaluated in T2*-weighted dynamic contrast enhanced (DCE)-MR images. From the recalculated each parameters, perfusion weighted image were outlined by using modified non-linear curve fitting algorithm. This results were improved estimation of T2*-weighted dynamic series. Conclusion: The present study demonstrated an improvement of an estimation of kinetic parameters from dynamic contrast-enhanced (DCE) T2*-weighted magnetic resonance imaging data, using contrast agents. The advanced kinetic models include the relation of volume transfer constant $K^{trans}\;(min^{-1})$ and the volume of extravascular extracellular space (EES) per unit volume of tissue $\nu_e$.

• Investigative Magnetic Resonance Imaging
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• 제23권3호
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• pp.220-227
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• 2019

Purpose: To evaluate the usefulness of wash-in color map in detecting early enhancement of prostate focal lesion compared to whole dynamic contrast-enhanced MRI (DEC MRI) images. Materials and Methods: This study engaged 50 prostate cancer patients who underwent multiparametric MRI and radical prostatectomy as subjects. An expert [R1] and a trainee [R2] independently evaluated early enhancement and recorded the time needed to review 1) a wash-in color map and 2) whole DCE MRI images. Results: The review of whole DCE images by R1 showed fair agreement with color map by R1, whole images by R2, and color map by R2 (weighted kappa values = 0.59, 0.44, and 0.58, respectively). Both readers took a significantly shorter time to review the color maps as compared to whole images (P < 0.001). Conclusion: A trainee could achieve better agreement with an expert when using wash-in color maps than when using whole DCE MRI images. Also, color maps took a significantly shorter evaluation time than whole images.

• Korean Journal of Radiology
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• 제22권8호
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• pp.1352-1368
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• 2021

Objective: For an accurate dynamic contrast-enhanced (DCE) MRI analysis, exact baseline T1 mapping is critical. The purpose of this study was to compare the pharmacokinetic parameters of DCE MRI using synthetic MRI with those using fixed baseline T1 values. Materials and Methods: This retrospective study included 102 patients who underwent both DCE and synthetic brain MRI. Two methods were set for the baseline T1: one using the fixed value and the other using the T1 map from synthetic MRI. The volume transfer constant (K^trans), volume of the vascular plasma space (v_p), and the volume of the extravascular extracellular space (v_e) were compared between the two methods. The interclass correlation coefficients and the Bland-Altman method were used to assess the reliability. Results: In normal-appearing frontal white matter (WM), the mean values of K^trans, v_e, and v_p were significantly higher in the fixed value method than in the T1 map method. In the normal-appearing occipital WM, the mean values of v_e and v_p were significantly higher in the fixed value method. In the putamen and head of the caudate nucleus, the mean values of K^trans, v_e, and v_p were significantly lower in the fixed value method. In addition, the T1 map method showed comparable interobserver agreements with the fixed baseline T1 value method. Conclusion: The T1 map method using synthetic MRI may be useful for reflecting individual differences and reliable measurements in clinical applications of DCE MRI.

• Investigative Magnetic Resonance Imaging
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• 제11권2호
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• pp.103-109
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• 2007

목적: 정상인의 뇌영역의 동적 자화율 대조도 (dynamic susceptibility contrast)에서 새로운 비선형 곡선조화 알고리즘을 사용한 Gd-DTPA의 비투과성 (non-permeability)을 조사하고자 한다. 대상 및 방법: 전반적인 혈관내의 이동에 대한 전달함수($K^{trans}$)에 대하여 첫 번째 통과된 조합변수인자의 화소에 대한 정량적인 분석을 실시하였다. 정확한 복셀값의 산출을 위하여 개선된 알고리즘에 의한 경계값을 적용하여 최적화 과정을 반복수행하였다. 결과: 비선형 곡선조화 알고리즘을 적용함으로서, 뇌혈류와 뇌혈류량 측정은 $T2^*$-강조 dynamic contrast enhanced (DCE)에서 상당히 개선 되었다. 재산출된 인자들로부터 뇌관류 강조영상의 형성은 수정된 비선형 곡선조화 알고리즘을 사용하여 획득하였다. 가상공간의 계산과 데이터 입력은 $T2^*$-강조 DCE 영상에서 조영제 포화도를 산출하였다. 결론: 본 연구에서 개발한 새로운 비선형 곡선조화 알고리즘을 사용하여 DCE-$T2^*$ 강조 자기공명영상 데이터를 얻은 후에 역동학적 인자들의 정확성 및 효율성을 개선시키는데 도움을 주는 것으로 확인되었다.

• Korean Journal of Radiology
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• 제21권6호
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• pp.707-716
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• 2020

Objective: To evaluate pharmacokinetic variables from contrast-enhancing lesions (CELs) and non-enhancing T2 high signal intensity lesions (NE-T2HSILs) on dynamic contrast-enhanced (DCE) magnetic resonance (MR) imaging for predicting progression-free survival (PFS) in glioblastoma (GBM) patients. Materials and Methods: Sixty-four GBM patients who had undergone preoperative DCE MR imaging and received standard treatment were retrospectively included. We analyzed the pharmacokinetic variables of the volume transfer constant (Ktrans) and volume fraction of extravascular extracellular space within the CEL and NE-T2HSIL of the entire tumor. Univariate and multivariate Cox regression analyses were performed using preoperative clinical characteristics, pharmacokinetic variables of DCE MR imaging, and postoperative molecular biomarkers to predict PFS. Results: The increased mean Ktrans of the CEL, increased 95th percentile Ktrans of the CELs, and absence of methylated O⁶-methylguanine-DNA methyltransferase promoter were relevant adverse variables for PFS in the univariate analysis (p = 0.041, p = 0.032, and p = 0.083, respectively). The Kaplan-Meier survival curves demonstrated that PFS was significantly shorter in patients with a mean Ktrans of the CEL > 0.068 and 95th percentile Ktrans of the CEL > 0.223 (log-rank p = 0.038 and p = 0.041, respectively). However, only mean Ktrans of the CEL was significantly associated with PFS (p = 0.024; hazard ratio, 553.08; 95% confidence interval, 2.27-134756.74) in the multivariate Cox proportional hazard analysis. None of the pharmacokinetic variables from NE-T2HSILs were significantly related to PFS. Conclusion: Among the pharmacokinetic variables extracted from CELs and NE-T2HSILs on preoperative DCE MR imaging, the mean Ktrans of CELs exhibits potential as a useful imaging predictor of PFS in GBM patients.

• Investigative Magnetic Resonance Imaging
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• 제21권1호
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• pp.43-50
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• 2017

Chronic expanding organizing hematoma (CEH) occasionally mimics a soft tissue tumor on MRI, which becomes more problematic in patients with a history of surgical resection for musculoskeletal malignancy. Herein, we present a case of CEH which we were able to differentiate from recurrent tumor through MRI follow-up, including diffusion-weighted imaging (DWI) and dynamic contrast enhanced (DCE) imaging. A 66-year-old male visited our institution under suspicion of recurrent leiomyosarcoma of the thigh, 19 months after surgery and radiation therapy. Due to inconclusive results, three US-guided biopsies and 6 MRI examinations were performed over 2 years. In the end, we could diagnose a CEH using conventional and functional MRI techniques, and it was histopathologically confirmed after surgical resection. A CEH may occur remotely after an initiating event, and it may persist and expand over several years. Functional MR sequences, in addition to conventional sequences, are helpful in differentiating CEH from malignant neoplasms.

• Investigative Magnetic Resonance Imaging
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• 제15권2호
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• pp.91-101
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• 2011

관류 자기공명영상은 크게 외인성과 내인성 조영제를 사용하는 방법으로 나눌 수 있고, 외인성 조영제를 사용하는 방법으로는 DSC 와 DCE 방법이 있으며, 내인성 조영제를 사용하는 방법으로는 ASL 이 있다. 이들 관류 자기공명영상 방법들은 환자의 상태와 나타내고자 하는 영상인자에 따라 선별적으로 최적화되어 사용되어야 한다. 그 예로 급성 뇌졸중 환자의 경우 매우 빠른 영상획득이 최우선적인 인자이므로 DSC 가 주로 이용되고 있고, 뇌종양 환자의 경우 여러 물리적 인자를 고려한 DSC 혹은 DCE 스캔이 필요하다. 또한 소아나 가임여성 및 신장병질환이 있는 경우는 ASL 을 이용되고 있다. 관류 자기공명영상 기술은 방사성 물질을 전혀 사용하지 않아 약물효과의 평가와 기타 치료 효과를 이해하는데 많은 응용이 있을 것으로 생각된다.

• Korean Journal of Radiology
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• 제22권8호
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• pp.1369-1378
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• 2021

Objective: Few attempts have been made to investigate the prognostic value of dynamic contrast-enhanced (DCE) MRI or dynamic susceptibility contrast (DSC) MRI of non-enhancing, T2-high-signal-intensity (T2-HSI) lesions of glioblastoma multiforme (GBM) in newly diagnosed patients. This study aimed to investigate the prognostic values of DCE MRI and DSC MRI parameters from non-enhancing, T2-HSI lesions of GBM. Materials and Methods: A total of 76 patients with GBM who underwent preoperative DCE MRI and DSC MRI and standard treatment were retrospectively included. Six months after surgery, the patients were categorized into early progression (n = 15) and non-early progression (n = 61) groups. We extracted and analyzed the permeability and perfusion parameters of both modalities for the non-enhancing, T2-HSI lesions of the tumors. The optimal percentiles of the respective parameters obtained from cumulative histograms were determined using receiver operating characteristic (ROC) curve and univariable Cox regression analyses. The results were compared using multivariable Cox proportional hazards regression analysis of progression-free survival. Results: The 95th percentile value (PV) of Ktrans, mean Ktrans, and median Ve were significant predictors of early progression as identified by the ROC curve analysis (area under the ROC curve [AUC] = 0.704, p = 0.005; AUC = 0.684, p = 0.021; and AUC = 0.670, p = 0.0325, respectively). Univariable Cox regression analysis of the above three parametric values showed that the 95th PV of Ktrans and the mean Ktrans were significant predictors of early progression (hazard ratio [HR] = 1.06, p = 0.009; HR = 1.25, p = 0.017, respectively). Multivariable Cox regression analysis, which also incorporated clinical parameters, revealed that the 95th PV of Ktrans was the sole significant independent predictor of early progression (HR = 1.062, p < 0.009). Conclusion: The 95th PV of Ktrans from the non-enhancing, T2-HSI lesions of GBM is a potential prognostic marker for disease progression.

• Korean Journal of Radiology
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• 제24권5호
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• pp.444-453
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• 2023

Objective: Meningeal lymphatic vessels are predominantly located in the parasagittal dural space (PSD); these vessels drain interstitial fluids out of the brain and contribute to the glymphatic system. We aimed to investigate the ability of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in assessing the dynamic changes in the meningeal lymphatic vessels in PSD. Materials and Methods: Eighteen participants (26-71 years; male:female, 10:8), without neurological or psychiatric diseases, were prospectively enrolled and underwent DCE-MRI. Three regions of interests (ROIs) were placed on the PSD, superior sagittal sinus (SSS), and cortical vein. Early and delayed enhancement patterns and six kinetic curve-derived parameters were obtained and compared between the three ROIs. Moreover, the participants were grouped into the young (< 65 years; n = 9) or older (≥ 65 years; n = 9) groups. Enhancement patterns and kinetic curve-derived parameters in the PSD were compared between the two groups. Results: The PSD showed different enhancement patterns than the SSS and cortical veins (P < 0.001 and P < 0.001, respectively) in the early and delayed phases. The PSD showed slow early enhancement and a delayed wash-out pattern. The six kinetic curve-derived parameters of PSD was significantly different than that of the SSS and cortical vein. The PSD washout rate of older participants was significantly lower (median, 0.09; interquartile range [IQR], 0.01-0.15) than that of younger participants (median, 0.32; IQR, 0.07-0.45) (P = 0.040). Conclusion: This study shows that the dynamic changes of meningeal lymphatic vessels in PSD can be assessed with DCE-MRI, and the results are different from those of the venous structures. Our finding that delayed wash-out was more pronounced in the PSD of older participants suggests that aging may disturb the meningeal lymphatic drainage.