• Investigative Magnetic Resonance Imaging
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• v.23 no.3
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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.

• Investigative Magnetic Resonance Imaging
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• v.26 no.1
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• pp.60-65
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• 2022

Gadoxetic acid-enhanced magnetic resonance imaging (MRI) has been widely used to detect and characterize focal hepatic lesions. Because gadoxetic acid is a hepatocyte-specific contrast agent, its patterns during hepatobiliary phase enhancement provide useful information for differential diagnoses of focal hepatic lesions. Hepatic angiomyolipoma (AML) is a rare mesenchymal hepatic neoplasm composed of blood vessels, epithelioid cells, and varying amounts of adipose tissue components. Hepatic AMLs usually show marked hypointensity during the hepatobiliary phase of gadoxetic acid-enhanced MRI as hepatic AMLs are devoid of hepatocytes and fibrotic components. The present study describes a patient with hepatic AML and an atypical imaging feature. This tumor showed hyperintensity during the hepatobiliary phase of gadoxetic acid-enhanced MRI, mimicking hepatocellular tumors such as hepatocellular adenoma. The hepatobiliary hyperintensity of this lesion was likely due to multifocal entrapped hepatocytes resulting from an intrasinusoidal growth pattern of tumor cells and insufficient hepatic parenchymal enhancement during the hepatobiliary phase of gadoxetic acid-enhanced MRI.

• Investigative Magnetic Resonance Imaging
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• v.19 no.1
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• pp.47-51
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• 2015

Sarcomatous Intrahepatic cholangiocarcinoma is a rare but an aggressive variant of cholangiocarcinoma with a very poor prognosis. A 79-year-old man was admitted to our hospital because of incidentally found liver mass. Magnetic resonance imaging (MRI) revealed well-defined hypointense mass on T1WI and heterogeneous hyperintense mass on T2WI. Gd-EOB-DTPA enhanced study shows peripheral rim-like enhancement in arterial phase and progressive concentric filling of contrast in delayed phase. And mass shows significant enhancement in hepatobiliary phase. The pathologic diagnosis was intrahepatic cholangiocarcinoma with sarcomatous change.

• Investigative Magnetic Resonance Imaging
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• v.26 no.1
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• pp.32-42
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• 2022

Purpose: To evaluate the clinical benefit of 2D contrast-enhanced T2 fluid-attenuated inversion recovery (CE-T2 FLAIR) image for detecting leptomeningeal metastasis (LM) in the brain metastasis work-up for lung cancer. Materials and Methods: From June 2017 to July 2019, we collected all consecutive patients with lung cancer who underwent brain magnetic resonance image (MRI), including contrast-enhanced 3D fast spin echo T1 black-blood image (CE-T1WI) and CE-T2 FLAIR; we recruited clinico-radiologically suspected LM cases. Two independent readers analyzed the images for LM in three sessions: CE-T1WI, CE-T2 FLAIR, and their combination. Results: We recruited 526 patients with suspected lung cancer who underwent brain MRI; of these, we excluded 77 (insufficient image protocol, unclear pathology, different contrast media, poor image quality). Of the 449 patients, 34 were clinico-radiologically suspected to have LM; among them, 23 were diagnosed with true LM. The calculated detection performance of CE-T1WI, CE-T2 FLAIR, and combined analysis obtained from the 34 suspected LM were highest in the combined analysis (AUC: 0.80, 0.82, and 0.89, respectively). The inter-observer agreement was also the highest in the combined analysis (0.68, 0.72, and 0.86, respectively). In quantitative analyses, CNR of CE-T2 FLAIR was significantly higher than that of CE-T1WI (Wilcoxon signed rank test, P < 0.05). Conclusion: Adding CE-T2 FLAIR might provide better detection for LM in the brain-metastasis screening for lung cancer.

• Investigative Magnetic Resonance Imaging
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• v.23 no.1
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• pp.34-37
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• 2019

Gadolinium contrast agents (CAs) are integral components of clinical magnetic resonance imaging (MRI). However, safety concerns have arisen regarding the use of gadolinium CAs, due to their association with nephrogenic systemic fibrosis (NSF). Furthermore, recently the long-term retention of $Gd^{3+}-based$ CAs in brains patients with normal renal function raised another possible safety issue. The safety concerns of $Gd^{3+}-based$ CAs have been based on the ligand structure of $Gd^{3+}-based$ CAs, and findings that $Gd^{3+}-based$ CAs with linear ligand structures showed much higher incidences of NSF and brain retention of CAs than $Gd^{3+}-based$ CAs with macrocyclic ligand structure. In the current study, we report the in vivo biodistribution profile of a new highly stable multifunctional $Gd^{3+}-based$ CA, with macrocyclic ligand structure (HNP-2006). MR imaging using HNP-2006 demonstrated a significant contrast enhancement in many different organs. Furthermore, the contrast enhanced tumor imaging using HNP-2006 confirmed that this new macrocyclic CA can be used for detecting tumor in the central nervous system. Therefore, this new multifunctional HNP-2006 with macrocyclic ligand structure shows great promise for whole-body clinical application.

• Investigative Magnetic Resonance Imaging
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• v.21 no.3
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• pp.131-138
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• 2017

Purpose: To optimize the timing of scans using cardiac magnetic resonance contrast-enhanced timing robust angiography (CMR-CENTRA) for electroanatomic mapping (EAM) of the right atrium (RA) and left atrium (LA) in patients with atrial fibrillation (AF). Materials and Methods: Fifty patients with AF (38 men; mean age, $59.6{\pm}9.3years$) underwent CMR-CENTRA in preparation for EAM. The CMR-CENTRA data were acquired at five different scan times: 0 seconds, 5 seconds, 10 seconds, 15 seconds, and 20 seconds after an intravenous injection of contrast media. To evaluate the degree of contrast enhancement, right atrial relative contrast (RA-RC) and left atrial relative contrast (LA-RC) on the CMR-CENTRA scans were assessed at each time point. The three-dimensional (3D) reconstruction of the RA and LA for the EAM system was performed using the CMR-CENTRA data. Results: A CMR-CENTRA at a scan time of 10 seconds showed significantly greater LA-RC (P < 0.05) compared with all other scan times. A CMR-CENTRA at a scan time of 15 seconds showed significantly greater RA-RC (P < 0.05) compared with all other scan times. In the 3D reconstruction of the RA, the success rates of CMR-CENTRA at scan times of 10 seconds and 15 seconds were 18% and 100%, respectively. In the 3D reconstruction of the LA, the success rates of CMR-CENTRA at 10- and 15-second scan times were 100%. Conclusion: The CMR-CENTRA data acquired at 15 seconds after the injection of contrast media is appropriate for the preparation of an EAM system that is focused on the RA and LA in patients with AF.

• Childhood Kidney Diseases
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• v.26 no.2
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• pp.101-106
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• 2022

Nephrotic syndrome (NS) is a hypercoagulable state in which children are at risk of venous thromboembolism. A higher risk has been reported in children with steroid-resistant NS than in those with steroid-sensitive NS. The mortality rate of cerebral venous sinus thrombosis (CVST) is approximately 10% and generally results from cerebral herniation in the acute phase and an underlying disorder in the chronic phase. Our patient initially manifested as a child with massive proteinuria and generalized edema. He was treated with albumin replacement and diuretics, angiotensin-converting enzyme inhibitor, and deflazacort. Non-contrast computed tomography showed areas of hyperattenuation in the superior sagittal sinus when he complained of severe headache and vomiting. Subsequent magnetic resonance imaging revealed empty delta signs in the superior sagittal, lateral transverse, and sigmoid sinuses, suggesting acute CVST. Immediate anticoagulation therapy was started with unfractionated heparin, antithrombin III replacement, and continuous antiproteinuric treatment. The current report describes a life-threatening CVST in a child with steroid-dependent NS, initially diagnosed by contrast non-enhanced computed tomography and subsequently confirmed by contrast-enhanced magnetic resonance imaging, followed by magnetic resonance venography for recanalization, addressing successful treatment.

• Korean Journal of Radiology
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• v.24 no.10
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• pp.983-995
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• 2023

Objective: To compare the diagnostic performance and interobserver agreement between contrast-enhanced computed tomography (CECT) and contrast-enhanced magnetic resonance imaging (CE-MRI) with magnetic resonance cholangiopancreatography (MRCP) for evaluating the resectability in patients with extrahepatic cholangiocarcinoma (eCCA). Materials and Methods: This retrospective study included treatment-naïve patients with pathologically confirmed eCCA, who underwent both CECT and CE-MRI with MRCP using extracellular contrast media between January 2015 and December 2020. Among the 214 patients (146 males; mean age ± standard deviation, 68 ± 9 years) included, 121 (56.5%) had perihilar cholangiocarcinoma. R0 resection was achieved in 108 of the 153 (70.6%) patients who underwent curative-intent surgery. Four fellowship-trained radiologists independently reviewed the findings of both CECT and CE-MRI with MRCP to assess the local tumor extent and distant metastasis for determining resectability. The pooled area under the receiver operating characteristic curve (AUC), sensitivity, and specificity of CECT and CE-MRI with MRCP were compared using clinical, surgical, and pathological findings as reference standards. The interobserver agreement of resectability was evaluated using Fleiss kappa (κ). Results: No significant differences were observed between CECT and CE-MRI with MRCP in the pooled AUC (0.753 vs. 0.767), sensitivity (84.7% [366/432] vs. 90.3% [390/432]), and specificity (52.6% [223/424] vs. 51.4% [218/424]) (P > 0.05 for all). The AUC for determining resectability was higher when CECT and CE-MRI with MRCP were reviewed together than when CECT was reviewed alone in patients with discrepancies between the imaging modalities or with indeterminate resectability (0.798 [0.754-0.841] vs. 0.753 [0.697-0.808], P = 0.014). The interobserver agreement for overall resectability was fair for both CECT (κ = 0.323) and CE-MRI with MRCP (κ = 0.320), without a significant difference (P = 0.884). Conclusion: CECT and CE-MRI with MRCP showed no significant differences in the diagnostic performance and interobserver agreement in determining the resectability in patients with eCCA.

• Journal of the Korean Magnetic Resonance Society
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• v.9 no.2
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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 $\nu_e$.

• Proceedings of the KSMRM Conference
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• 2003.10a
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• pp.44-44
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• 2003

To determine feasibility of contrast-enhanced MRI (co-MRI) at true end-diastole (ED) free from limitation of time for inversion-recovery and trigger window for quantifying transmural extent of infarction. 대상 및 방법： MRI was performed in 18 patients with myocardial infarction. Cine imaging and co-MRI with same registered slices in short axis were peformed. To allow true ED co-MRI, ECG synchronization should use two RR-intervals for one acquisition of a segment of k-space by setting the heart rate to half that of the true heart rate. Trigger delay time was adjusted to the RR-interval for imaging at ED and to the sum of RR-interval plus the time between R-wave and the end-systole (ES) determined in cine images for imaging at ES.