• Journal of Korean Neurosurgical Society
• /
• 제50권4호
• /
• pp.388-391
• /
• 2011

A lesion that is hyperintense on diffusion-weighted imaging (DWI) and hypointense on the apparent diffusion coefficient (ADC) map is a characteristic magnetic resonance imaging (MRI) finding in acute ischemic infarction. In some cases, however, these findings can persist for a few months after infarct onset. It is thought that these finding reflect the different evolution speeds of the infarcted tissue. We report a patient with a right middle cerebral artery territory infarction with persistent hyperintensity on DWI and hypointensity on the ADC map for over 8 months. To our knowledge, this is the most persistent case of hyperintensity lesion on DWI and the serial MRI images of this patient provide important information on the evolution of infarcted tissue.

• 한국의학물리학회:학술대회논문집
• /
• 한국의학물리학회 2002년도 Proceedings
• /
• pp.356-358
• /
• 2002

MRI, particularly diffusion weighted imaging (DWI), plays vital roles in detection of the acute brain infarction$\^$1-4/ and others metabolic changes of biological tissues. In general, every molecule in biological tissues may diffuse and move randomly in three-dimensional space. However, in clinical diagnosis, only 2D-DWI is used. The authors have developed a new method for rapid three-dimensional DWI (3D-DWI). In this method, by refocusing of the magnetized spin with the applied gradient field, direction of which is opposite to phase encoding field. Magnetized spin of $^1$H is kept under the SSFP (steady state free precession)$\^$5-6/. Under SSFP, in addition of FID, spin echo and stimulated echo are also generated, so the acquired signal is increased. The signal intensity is increased depending on flip angle (FA) of magnetized spin. This phenomenon is confirmed by human brain and phantom studies. The performance of this method is quantitatively analyzed by using both of conventional spin echo DWI and 3D-DWI. From experimental results, three dimensional diffusion weighted images are obtained correctly for liquid phantoms (water, acetone and oil), diffusion coefficient is enhanced in each image. Therefore, this method will provide useful information for clinical diagnosis.

• Korean Journal of Radiology
• /
• 제21권9호
• /
• pp.1036-1044
• /
• 2020

Objective: To investigate the clinical feasibility of synthetic diffusion-weighted imaging (sDWI) at different b-values in patients with breast cancer by assessing the diagnostic image quality and the quantitative measurements compared with conventional diffusion-weighted imaging (cDWI). Materials and Methods: Fifty patients with breast cancer were assessed using cDWI at b-values of 800 and 1500 s/mm² (cDWI₈₀₀ and cDWI₁₅₀₀) and sDWI at b-values of 1000 and 1500 s/mm² (sDWI₁₀₀₀ and sDWI₁₅₀₀). Qualitative analysis (normal glandular tissue suppression, overall image quality, and lesion conspicuity) was performed using a 4-point Likert-scale for all DWI sets and the cancer detection rate (CDR) was calculated. We also evaluated cancer-to-parenchyma contrast ratios for each DWI set in 45 patients with the lesion identified on any of the DWI sets. Statistical comparisons were performed using Friedman test, one-way analysis of variance, and Cochran's Q test. Results: All parameters of qualitative analysis, cancer-to-parenchyma contrast ratios, and CDR increased with increasing b-values, regardless of the type of imaging (synthetic or conventional) (p < 0.001). Additionally, sDWI₁₅₀₀ provided better lesion conspicuity than cDWI₁₅₀₀ (3.52 ± 0.92 vs. 3.39 ± 0.90, p < 0.05). Although cDWI₁₅₀₀ showed better normal glandular tissue suppression and overall image quality than sDWI₁₅₀₀ (3.66 ± 0.78 and 3.73 ± 0.62 vs. 3.32 ± 0.90 and 3.35 ± 0.81, respectively; p < 0.05), there was no significant difference in their CDR (90.0%). Cancer-to-parenchyma contrast ratios were greater in sDWI₁₅₀₀ than in cDWI₁₅₀₀ (0.63 ± 0.17 vs. 0.55 ± 0.18, p < 0.001). Conclusion: sDWI₁₅₀₀ can be feasible for evaluating breast cancers in clinical practice. It provides higher tumor conspicuity, better cancer-to-parenchyma contrast ratio, and comparable CDR when compared with cDWI₁₅₀₀.

• Investigative Magnetic Resonance Imaging
• /
• 제20권4호
• /
• pp.250-253
• /
• 2016

Acute Japanese encephalitis (JE) is an endemic viral infectious disease in various parts of Far East and Southeast Asian countries including Korea. Bilateral thalami are the most common involving sites in JE. Other areas including the basal ganglia, substantia nigra, red nucleus, pons, cerebral cortex and cerebellum may be also involved. We report an extremely unusual brain diffusion-weighted MR imaging (DWI) findings in a 53-year-old man with serologically proven JE involving unilateral deep gray matter and temporal lobe, which shows multifocal high signal intensities in left thalamus, left substantia nigra, left caudate nucleus and left medial temporal cortex on T2-weighted image and DWI with iso-intensity on apparent diffusion coefficient (ADC) map.

• Asian Pacific Journal of Cancer Prevention
• /
• 제15권16호
• /
• pp.6843-6848
• /
• 2014

Background: Diffusion-weighted magnetic resonance imaging (DWI) is reported to be useful for detecting malignant lesions. The purpose of this study is to clarify characteristics of imaging, detection rate and sensitivity of DWI for recurrence or metastasis of lung cancer. Methods: A total of 36 lung cancer patients with recurrence or metastasis were enrolled in this study. While 16 patients underwent magnetic resonance imaging (MRI), computed tomography (CT) and positron emission tomography-computed tomography (PET-CT), 17 underwent MRI and CT, and 3 underwent MRI and PET-CT. Results: Each recurrence or metastasis showed decreased diffusion, which was easily recognized in DWI. The detection rate for recurrence or metastasis was 100% (36/36) in DWI, 89% (17/19) in PET-CT and 82% (27/33) in CT. Detection rate of DWI was significantly higher than that of CT (p=0.0244) but not significantly higher than that of PET-CT (p=0.22). When the optimal cutoff value of the apparent diffusion coefficient value was set as $1.70{\times}10^{-3}mm^2/sec$, the sensitivity of DWI for diagnosing recurrence or metastasis of lung cancer was 95.6%. Conclusions: DWI is useful for detection of recurrence and metastasis of lung cancer.

• Asian Pacific Journal of Cancer Prevention
• /
• 제15권19호
• /
• pp.8271-8277
• /
• 2014

Aims: Apparent diffusion coefficient (ADC) values of nodes in diffusion-weighted imaging (DWI) are widely used in differentiating metastatic from non-metastatic lymph nodes. The purpose of this meta-analysis was to demonstrate whether DWI could contribute to the precise diagnosis of breast cancer (BC) with and without lymph node metastasis (LNM). Materials and Methods: English and Chinese electronic databases were searched for relevant studies followed by a comprehensive literature search. Two reviewers independently assessed the methodological quality of the included trials based on the quality assessment of diagnostic accuracy studies (QUADAS). Summary odds ratios (ORs) and corresponding 95% confidence intervals (95% CIs) were calculated. Results: Final analysis of 624 BC subjects (patients with LNM = 254, patients without LNM = 370) were incorporated into the current meta-analysis from 9 eligible cohort studies. Combined ORs of ADCs suggested that ADC values in BC patients without LNM were higher than in patients with LNM (OR=0.56, 95%CI: 0.11-1.01, p=0.015). Subgroup analysis stratified by country indicated a low ADC value in BC patients with LNM rather than those without LNM among Chinese (OR=1.27, 95%CI: 0.89-1.66, p<0.001), Italians (OR=0.75, 95%CI: 0.13-1.38, p=0.018), and Egyptians (OR=1.27, 95%CI: 0.71-1.84, p<0.001). The findings of subgroup analysis by MRI machine type revealed that ADC values from diffusion MRI may be potential diagnostic indicators for BC using Non-Philips 1.5T (OR=1.10, 95%CI: 0.84-1.36, p<0.001). Conclusions: The main findings of our meta-analysis demonstrated that increased signal intensity on DWI and decreased signals on ADC are helpful in diagnosis of BC patients with or without LNM. DWI could therefore be an important imaging investigation in patients suspected of BC.

• Asian Pacific Journal of Cancer Prevention
• /
• 제16권8호
• /
• pp.3407-3412
• /
• 2015

Background: The aim of this study was to evaluate and compare the accuracy of diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC) value, and time-intensity curve (TIC) type analysis derived from dynamic contrast-enhanced MR imaging (DCE-MRI) in differentiating benign from malignant adnexal masses. Materials and Methods: 47 patients with 56 adnexal masses (27 malignant and 29 benign) underwent DWI and DCE-MRI examinations, prior to surgery. DWI signal intensity, mean ADC value, and TIC type were determined for all the masses. Results: High signal intensity on DWI and type 3 TIC were helpful in differentiating benign from malignant adnexal masses (p<0.001). The mean ADC value was significantly lower in malignant adnexal masses (p<0.001). An ADC value< $1.20{\times}10^{-3}mm^2/s$ may be the optimal cutoff for differentiating between benign and malignant tumors. The negative predictive value for low signal intensity on DWI, and type 1 TIC were 100%. The pairwise comparison among the receiver operating characteristic (ROC) curves showed that the area under the curve (AUC) of TIC was significantly larger than the AUCs of DWI and ADC (p<0.001 for comparison of TIC and DWI, p<0.02 for comparison of TIC and ADC value). Conclusions: DWI, ADC value and TIC type derived from DCE-MRI are all sensitive and relatively specific methods for differentiating benign from malignant adnexal masses. By comparing these functional MR techniques, TIC was found to be more accurate than DWI and ADC.

• Investigative Magnetic Resonance Imaging
• /
• 제26권1호
• /
• pp.20-31
• /
• 2022

Purpose: To assess conventional MRI features associated with residual soft-tissue sarcomas following unplanned excision (UPE), and to compare the diagnostic performance of conventional MRI only with that of MRI including diffusion-weighted imaging (DWI) for residual tumors after UPE. Materials and Methods: We included 103 consecutive patients who had received UPE of a soft-tissue sarcoma with wide excision of the tumor bed between December 2013 and December 2019 and who also underwent conventional MRI and DWI in this retrospective study. The presence of focal enhancement, soft-tissue edema, fascial enhancement, fluid collections, and hematoma on MRI including DWI was reviewed by two musculoskeletal radiologists. We used classification and regression tree (CART) analysis to identify the most significant MRI features. We compared the diagnostic performances of conventional MRI and added DWI using the McNemar test. Results: Residual tumors were present in 69 (66.9%) of 103 patients, whereas no tumors were found in 34 (33.1%) patients. CART showed focal enhancement to be the most significant predictor of residual tumors and correctly predicted residual tumors in 81.6% (84/103) and 78.6% (81/103) of patients for Reader 1 and Reader 2, respectively. Compared with conventional MRI only, the addition of DWI for Reader 1 improved specificity (32.8% vs. 56%, 33.3% vs. 63.0%, P < 0.05), decreased sensitivity (96.8% vs. 84.1%, 98.7% vs. 76.7%, P < 0.05), without a difference in diagnostic accuracy (76.7% vs. 74.8%, 72.9% vs. 71.4%) in total and in subgroups. For Reader 2, diagnostic performance was not significantly different between the sets of MRI (P > 0.05). Conclusion: After UPE of a soft-tissue sarcoma, the presence or absence of a focal enhancement was the most significant MRI finding predicting residual tumors. MRI provided good diagnostic accuracy for detecting residual tumors, and the addition of DWI to conventional MRI may increase specificity.

• Investigative Magnetic Resonance Imaging
• /
• 제25권1호
• /
• pp.23-34
• /
• 2021

Purpose: Differentiating between glioblastoma and solitary metastasis is very important for the planning of further workup and treatment. We assessed the ability of various morphological parameters using conventional MRI and diffusion-based techniques to distinguish between glioblastomas and solitary metastases in tumoral and peritumoral regions. Materials and Methods: We included 38 patients with solitary brain tumors (21 glioblastomas, 17 solitary metastases). To find out if there were differences in the morphologic parameters of enhancing tumors, we analyzed their shape, margins, and enhancement patterns on postcontrast T1-weighted images. During analyses of peritumoral regions, we assessed the extent of peritumoral non-enhancing lesion on T2- and postcontrast T1-weighted images. We also aimed to detect peritumoral neoplastic cell infiltration by visual assessment of T2-weighted and diffusion-based images, including DWI, ADC maps, and exponential DWI, and evaluated which sequence depicted peritumoral neoplastic cell infiltration most clearly. Results: The shapes, margins, and enhancement patterns of tumors all significantly differentiated glioblastomas from metastases. Glioblastomas had an irregular shape, ill-defined margins, and a heterogeneous enhancement pattern; on the other hand, metastases had an ovoid or round shape, well-defined margins, and homogeneous enhancement. Metastases had significantly more extensive peritumoral T2 high signal intensity than glioblastomas had. In visual assessment of peritumoral neoplastic cell infiltration using T2-weighted and diffusion-based images, all sequences differed significantly between the two groups. Exponential DWI had the highest sensitivity for the diagnosis of both glioblastoma (100%) and metastasis (70.6%). A combination of exponential DWI and ADC maps was optimal for the depiction of peritumoral neoplastic cell infiltration in glioblastoma. Conclusion: In the differentiation of glioblastoma from solitary metastatic lesions, visual morphologic assessment of tumoral and peritumoral regions using conventional MRI and diffusion-based techniques can also offer diagnostic information.

• 한국방사선학회논문지
• /
• 제12권4호
• /
• pp.491-496
• /
• 2018

1.5Tesla와 3.0Tesla의 MRI 검사의 DWI (diffusion-weighted imaging) 펄스시퀀스에서 노이즈 스펙트럼을 분석하여 MRI검사의 기초자료를 제공하여 임상에서 적용하는데 목적이 있다. MRI 검사에서 ACR (American College of Radiology) 팬텀과 노이즈 스펙트럼은 Wavepad sound editor version 8.13 (NCH software, Green wood Village, CO, USA)로 FFT (fast Fourier transform), TFFT (time based fast Fourier transform)를 분석하였다. MR 1.5Tesla와 3.0Tesla의 DWI 펄스 시퀀스에서 검사실에 따른 노이즈 스펙트럼 및 FFT와 TFFT를 분석하였다. 1.5Tesla에 비해 3.0Tesla에서 FFT 및 TFFT에서 주파수 진폭의 노이즈 임계값은 1.5Tesla에서 -6 dB 사이였고, 3.0Tesla에서는 0 dB 사이로 분석되어 환자의 소음감소를 위한 DWI 펄스시퀀스를 환자에게 적절하게 임상에서 적용할 필요가 있다.