• Investigative Magnetic Resonance Imaging
• /
• v.14 no.2
• /
• pp.145-150
• /
• 2010

We report the case of a 16-year-old boy with a solid pancreatic mass which proved to be a nonfunctioning, malignant pancreatic neuroendocrine tumor (PNET). In pediatric patients, malignant pancreatic tumors are rare, especially malignant PNET. When dynamic contrast enhanced MRI showed a well enhancing solid pancreatic tumor on arterial and delayed phases and combined with malignant features, such as vascular invasion, invasion of adjascent organs, and lymphadenopathy, we should include malignant pancreatic neuroendocrine tumor in the differential diagnosis of childhood pancreatic tumors.

• Korean Journal of Radiology
• /
• v.21 no.6
• /
• pp.707-716
• /
• 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.

• Korean Journal of Radiology
• /
• v.22 no.7
• /
• pp.1152-1162
• /
• 2021

Objective: This study aimed to determine whether there are regional differences in the blood-brain barrier (BBB) permeability of cognitively normal elderly participants and to identify factors influencing BBB permeability with a clinically feasible, 10-minute dynamic contrast-enhanced (DCE) MRI protocol. Materials and Methods: This IRB-approved prospective study recruited 35 cognitively normal adults (26 women; mean age, 64.5 ± 5.6 years) who underwent DCE T1-weighted imaging. Permeability maps (K_trans) were coregistered with masks to calculate the mean regional values. The paired t test and Friedman test were used to compare Ktrans between different regions. The relationships between K_trans and the factors of age, sex, education, cognition score, vascular risk burden, vascular factors on imaging, and medial temporal lobar atrophy were assessed using Pearson correlation and the Spearman rank test. Results: The mean permeability rates of the right and left hippocampi, as assessed with automatic segmentation, were 0.529 ± 0.472 and 0.585 ± 0.515 (K_trans, x 10^-3 min^-1), respectively. Concerning the deep gray matter, the K_trans of the thalamus was significantly greater than those of the putamen and hippocampus (p = 0.007, p = 0.041). Regarding the white matter, the K_trans value of the occipital white matter was significantly greater than those of the frontal, cingulate, and temporal white matter (p < 0.0001, p = 0.0007, p = 0.0002). The variations in K_trans across brain regions were not related to age, cognitive score, vascular risk burden, vascular risk factors on imaging, or medial temporal lobar atrophy in the study group. Conclusion: Our study demonstrated regional differences in BBB permeability (K_trans) in cognitively normal elderly adults using a clinically acceptable 10-minutes DCE imaging protocol. The regional differences suggest that the integrity of the BBB varies across the brains of cognitively normal elderly adults. We recommend considering regional differences in K_trans values when evaluating BBB permeability in patients with neurodegenerative diseases.

• Investigative Magnetic Resonance Imaging
• /
• v.19 no.3
• /
• pp.137-145
• /
• 2015

Purpose: To investigate correlations of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor type 2 (HER2) statuses with magnetic resonance imaging (MRI) features and clinicohistological characteristics in patients with invasive lobular carcinoma (ILC). Materials and Methods: Data from 64 histologically confirmed ILCs were analyzed retrospectively. Preoperative breast MRI was reviewed for morphology and dynamic contrast-enhanced kinetics of the tumor. Pathologic reports were reviewed for ER, PR, and HER2 positivity, tumor size, lymph node metastasis, and the number of metastatic lymph nodes. Furthermore, there was an investigation of the MRI features and clinicohistologic characteristics, according to the ER, PR, and HER2 statuses. Results: A significant difference in MRI features and clinicohistological tumor characteristics were observed only in relation to PR status. Of the 64 ILCs, 10 (15.6%) were PR negative. PR negative cancers, compared with PR positive cancers, were more likely to present as non-mass enhancement (P = 0.027); have a significantly larger mean tumor size ($5.00{\pm}1.05cm$ vs. $2.57{\pm}0.21cm$, P = 0.021); and have significantly more metastatic lymph nodes (P = 0.010). Conclusion: PR negative ILC presented more frequently as non-mass enhancement on MRI, with larger tumors and increased numbers of metastatic lymph nodes. Therefore, the PR status plays an important role in determining MRI features and clinicohistological characteristics of ILC.

• Investigative Magnetic Resonance Imaging
• /
• v.23 no.4
• /
• pp.351-360
• /
• 2019

Purpose: To investigate noninvasive biomarkers for predicting treatment response in patients with locally advanced HCC who underwent concurrent chemoradiotherapy (CCRTx). Materials and Methods: Thirty patients (55.5 ± 10.2 years old, M:F = 24:6) who underwent CCRTx due to advanced HCC were enrolled. Contrast-enhanced US (CEUS) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) were obtained before and immediately after CCRTx. The third CEUS was obtained at one month after CCRTx was completed. Response was assessed at three months after CCRTx based on RECIST 1.1. Quantitative imaging biomarkers measured with CEUS and MRI were compared between groups. A cutoff value was calculated with ROC analysis. Overall survival (OS) was compared by the Breslow method. Results: Twenty-five patients were categorized into the non-progression group and five patients were categorized into the progression group. Peak enhancement of the first CEUS before CCRTx (PE1) was significantly lower in the non-progression group (median, 18.6%; IQR, 20.9%) than that in the progression group (median, 59.1%; IQR, 13.5%; P = 0.002). There was no significant difference in other quantitative biomarkers between the two groups. On ROC analysis, with a cutoff value of 42.6% in PE1, the non-progression group was diagnosed with a sensitivity of 90.9% and a specificity of 100%. OS was also significantly longer in patients with PE1 < 42.6% (P = 0.014). Conclusion: Early treatment response and OS could be predicted by PE on CEUS before CCRTx in patients with HCC.

• Journal of the Korean Society of Radiology
• /
• v.82 no.1
• /
• pp.29-48
• /
• 2021

Diffusion-weighted magnetic resonance imaging (DW MRI) is a fast unenhanced technique that shows promise as a stand-alone modality for cancer screening and characterization. Currently, DW MRI may have lower sensitivity than that of dynamic contrast-enhanced MRI as a standalone modality for breast cancer detection but superior to that of mammography, which may provide a useful alternative for supplemental screening. Standardized acquisition and interpretation of DW MRI can improve the image quality and reduce the variability of the results. Furthermore, high-resolution DW MRI, with advanced techniques and postprocessing, will facilitate better detection and characterization of subcentimeter cancers and reduce false-negatives and false-positives. Future results from ongoing prospective multicenter clinical trials using standardized and optimized protocols will facilitate the use of DW MRI as a stand-alone modality.

• Journal of the Korean Society of Radiology
• /
• v.84 no.1
• /
• pp.75-91
• /
• 2023

The technical parameters and imaging interpretation criteria of the Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) using multiparametric MRI (mpMRI) are updated in PI-RADS v2.1. These changes have been an expected improvement for prostate cancer evaluation, although some issues remain unsolved, and new issues have been raised. In this review, a brief overview of PI-RADS v2.1 is and several critical points are discussed as follows: the need for more detailed protocols of mpMRI, lack of validation of the revised transition zone interpretation criteria, the need for clarification for the revised diffusion-weighted imaging and dynamic contrast-enhanced imaging criteria, anterior fibromuscular stroma and central zone assessment, assessment of background signal and tumor aggressiveness, changes in the structured report, the need for the parameters for imaging quality and performance control, and indications for expansion of the system to include other indications.

• Journal of Yeungnam Medical Science
• /
• v.22 no.1
• /
• pp.43-51
• /
• 2005

Background: To examine the ultrasonographic and magnetic resonance (MRI) imaging findings of a cervical mass type cervical pregnancy. Materials and Methods: The ultrasonographic and MRI findings of 5 patients pathologically confirmed as having a cervical pregnancy were analyzed retrospectively. On ultrasonography, the size and echo pattern of the uterine cervix, the shape and echo pattern of the lesion, the degree and the pattern of blood flow on the color Doppler study and the spectral Doppler pattern were analyzed. The shape, signal intensity, and degree and pattern of enhancement of the lesion were evaluated on MRI. Results: The uterine cervix was enlarged and the size of the lesion was 6.1 to 7.1 (average, 6.5) cm. The endocervical canal was irregularly dilated and showed heterogeneous echogenicity in all 5 cases. Four of the 5 lesions were heterogeneously hyper- or mixed echoic and remaining one was relatively homogeneous echogenic. Doppler ultrasonography revealed an increased vascularity of the peritrophoblastic flow pattern. In all 4 cases where MRI performed, the lesion was irregular in shape and the margin was not sharply demarcated. The T2-weighed image showed that the lesions were mixed signal intensity. Three of the 4 lesions contained high signal intensity nodular portions and a low signal intensity rim was observed along the margin of the nodular portions. The T1-weighted image revealed multiple signal voids along the periphery of the lesions and high signal intensity portions as a result of hemorrhage were noted. The dynamic enhanced study showed that the high signal intensity portions on the T2-weighted image were strongly enhanced similar to the vessels on the early phase and the contrast enhancement gradually decreased with time. Conclusion: A cervical mass type cervical pregnancy can be correctly diagnosed using the patient's clinical symptom, the elevation in the serum ${\beta}$-HCG level, and characteristic ultrasonographic and MRI findings.

• Investigative Magnetic Resonance Imaging
• /
• v.26 no.1
• /
• pp.1-9
• /
• 2022

Artificial intelligence (AI) powered by deep learning (DL) has shown remarkable progress in image recognition tasks. Over the past decade, AI has proven its feasibility for applications in medical imaging. Various aspects of clinical practice in neuroimaging can be improved with the help of AI. For example, AI can aid in detecting brain metastases, predicting treatment response of brain tumors, generating a parametric map of dynamic contrast-enhanced MRI, and enhancing radiomics research by extracting salient features from input images. In addition, image quality can be improved via AI-based image reconstruction or motion artifact reduction. In this review, we summarize recent clinical applications of DL in various aspects of neuroimaging.

• Journal of Yeungnam Medical Science
• /
• v.26 no.1
• /
• pp.30-37
• /
• 2009

Purpose : To radiologically differentiate renal oncocytoma from other renal solid tumors, we analyzed and characterized, retrogradely, radiologic findings of renal oncocytomas. Materials and Methods : Radiologic findings of pathologically proven renal oncocytoma were analyzed in 9 patients. CT was performed in all patients, ultrasonography in 4 patients and MRI in 3 patients.(51) Results : On ultrasonography, the echogenicity of the mass was slightly more hyperechoic than normal renal parenchyma in all 4 cases. Two cases were homogeneous and the remaining two cases were relatively homogeneous. On CT, all 8 cases showed iso-density to slightly low density compared to normal renal parenchyma and 5 cases were homogeneous but the central portion of the mass was of a slightly lower density than the peripheral portion in 3 cases. All six cases had an arterial phase scan and were heterogeneously enhanced. An irregular, lower-enhancing portion was found in the central portion of the mass. Segmental inversion of contrast enhancement was found in 5 of 6 cases that had a dynamic enhancement study. On MR T1-weighted imaging, the mass was of iso-signal intensity to normal renal parenchyma and the central portion of the mass had a slightly hypo-signal intensity than the peripheral portion. On T2-weighted imaging, 2 cases were heterogeneous; the peripheral portion was of low signal intensity and central portion was of higher signal intensity than normal renal parenchyma. One case was relatively homogeneous and showed a slightly lower signal intensity than that of normal parenchyma, except for a central small portion showing high signal intensity. For 2 cases that had a dynamic study, a segmental inversion of contrast enhancement was noted. Conclusion : Renal oncocytoma is seen as a well-marginated solid mass lesion. On enhanced scans it is heterogeneously enhanced and segmental inversion of contrast enhancement may be seen. The possibility of oncocytoma can be suggested in cases showing these radiologic findings.