• Korean Journal of Radiology
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• v.22 no.8
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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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• v.23 no.1
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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.

• Korean Journal of Radiology
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• v.22 no.8
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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.

• Investigative Magnetic Resonance Imaging
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• v.21 no.1
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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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• v.24 no.3
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• pp.154-161
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• 2020

Purpose: A CT angiography spot sign (CTA-spot) is a significant predictor of the early expansion of an intracerebral hemorrhage (ICH-Ex). Dynamic-susceptibility-contrast magnetic resonance imaging (DSC-MRI) can track the real-time leaking of contrast agents. It may be able to indicate active bleeding, like a CTA-spot. Materials and Methods: From September 2014 to February 2017, we did non-contrast CT, CTA, and DSC-MRI examinations of seven patients with acute ICH. We investigated the time from symptom onset to the first contrast-enhanced imaging. We evaluated the time course of the contrast leak within the ICH at the source image of the DSC-MRI and the volume change of ICH between non-contrast CT and DSC-MRI. We compared the number of slices showing CTA-spots and DSC-MRI leaks. Results: The CTA-spot and DSC-MRI leak-sign were present in four patients, and two patients among those showed ICH-Ex. The time from the symptom onset to CTA or DSC-MRI was shorter for those with a DSC-MRI leak or CTA-spot than for three patients without either (70-130 minutes vs. 135-270 minutes). The leak-sign began earlier, lasted longer, and spread to more slices in the patients with ICH-Ex than in those without ICH-Ex. The number of slices of the DSC-MRI leak and the number of the CTA-spot were well correlated. Conclusion: DSC-MRI can demonstrate the leakage of GBCA within hyperacute ICH, showing the good contrast between hematoma and contrast. The DSC-MRI leakage sign could be related to the hematoma expansion in patients with ICH.

• Journal of the Korean Society of Radiology
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• v.85 no.2
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• pp.345-362
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• 2024

MRI plays an important role in abdominal imaging because of its ability to detect and characterize focal lesions. However, MRI examinations have several challenges, such as comparatively long scan times and motion management through breath-holding maneuvers. Techniques for reducing scan time with acceptable image quality, such as parallel imaging, compressed sensing, and cutting-edge deep learning techniques, have been developed to enable problem-solving strategies. Additionally, free-breathing techniques for dynamic contrast-enhanced imaging, such as extra-dimensional-volumetric interpolated breath-hold examination, golden-angle radial sparse parallel, and liver acceleration volume acquisition Star, can help patients with severe dyspnea or those under sedation to undergo abdominal MRI. We aimed to present various advanced abdominal MRI techniques for reducing the scan time while maintaining image quality and free-breathing techniques for dynamic imaging and illustrate cases using the techniques mentioned above. A review of these advanced techniques can assist in the appropriate interpretation of sequences.

• Journal of Korean Neurosurgical Society
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• v.29 no.12
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• pp.1570-1576
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• 2000

Objective : To evaluate objectively the sites of injury in patients with posttraumatic olfactory deficits and to suggest the diagnostic procedure for evaluation of posttraumatic anosmia. Methods : Ten patients with posttraumatic olfactory dysfunction were examined by means of olfactory testing, sinoscopy, contrast filled paranasal sinus computed tomography(contrast filled PNS CT) and magnetic resonance imaging(MRI). Five normal persons without olfactory dysfunction were also evauluated. The aerodynamic patency of olfactory cleft was examined by contrast filled PNS CT. The olfactory system(oflactory bulbs, olfactory tracts, inferior frontal region, hippocampi, or temporal lobes) was investigated in detail with MRI. The difference in the size of the olfactory bulb between normal volunteers and anosmic patients was evaluated by Student's t test. Results : Contrast filled dynamic CT scan was useful method for the evaluation of dynamic patency of the olfactory cleft. Paranasal CT scan of the all anosmic patients showed dynamic reflux of contrast media in olfactory cleft on valsalva maneuver. For the largest cross-sectional area and great height, the difference in olfactory bulb size between normal volunteers and patients was statistically significant(p<0.001) in MRI study. Conclusion : Posttraumatic anosmia was completely evaluated by olfactory testing, sinoscopy, and contrast filled CT scan for differentiation between conductive type and neurogenic type. Neurogenic anosmia was confirmed by perfect localization with MRI study.

• Korean Journal of Digital Imaging in Medicine
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• v.16 no.1
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• pp.27-33
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• 2014

The purpose of this study evaluated the hemo-dynamic information within 30 seconds clinically in 3D breast MRI. From January to March 2014, A total of 40 people were examined at 1.5 Tesla(Philips, Medical System, Achieva, The Netherlands) MRI equipments using 16 channel SENSE breast coil. The imaging parameters on vibrant are fellow as: $TR/TE/FA^{\circ}$/Matrix size/Slice thickness/Slab($5ms/2ms/10^{\circ}/180{\times}139{\times}2mm/80$). This study used a Gadovist and injected it with injection speed of 4 ml /sec by auto injector with 15 ml saline flushing. Firstly, for the delay time study, it divided three different delay time from immediately, 20 seconds, and 30 seconds. In quantitative analysis, the ROI signal intensities of tumor and surrounding tissues were measured retrospectively. In qualitative analysis, the image quality was scored from 1 to 5 point by one experienced radiological technologists as a visual test. The significance level of each delay time was evaluated with a one-way ANOVA(p<0.05). In the visual test, score levels on 30 seconds delay time was a little bit higher than others(p<0.05). The signal intensity of the tumor were $1445{\pm}360$, $1410{\pm}320$, $1510{\pm}415$ on immediately, 20 seconds, and 30 seconds and score levels were $4.18{\pm}0.85$, $3.54{\pm}0.94$, $4.45{\pm}0.74$(p<0.05). The data on immediate images showed better results than that others(p<0.05). Conclusively, Although it has been high scored in 30sec delay time for visual test in order to avoid failure in 20second, 30seconds delay time after contrast media administration, we recommend that the DCE 3D breast MRI commence immediately.

• Journal of the Korean Society of Radiology
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• v.82 no.2
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• pp.280-297
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• 2021

International guidelines recommended screening with ultrasonography (US) every 6 months for patients at risk for hepatocellular carcinoma (HCC). However, US demonstrates low sensitivity for the early detection of HCC. Magnetic resonance imaging (MRI) plays an important role in the noninvasive diagnosis of HCC, but it is not suitable for surveillance due to its lengthy examination and high cost. Therefore, several studies have been using various abbreviated MRI strategies, including noncontrast abbreviated MRI, dynamic contrast-enhanced abbreviated MRI, and abbreviated MRI using hepatobiliary phase image for HCC surveillance. In this article, we aim to review these various strategies and explore the future direction of HCC surveillance considering the cost-effectiveness aspect.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.148-148
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• 2006