• Title, Summary, Keyword: Diffusion-Weighted Imaging

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Electron Microscopy and MR Imaging Findings in Embolic Effects

  • Park Byung-Rae;Koo Bong-Oh
    • Biomedical Science Letters
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    • v.10 no.4
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    • pp.367-373
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    • 2004
  • Evaluated the hyperacute embolic effects of triolein and oleic acid in cat brains by using MR image and electron microscopy. In fat embolism, free fatty acid is more toxic than neutral fat in terms of tissue damage. T2-Weighted imaging, diffusion-weighted imaging, and contrast-enhanced T1-weighted imaging were performed in cat brains after the injection of triolein (group 1, n=8) or oleic acid (group 2, n=10) into the internal carotid artery. MR image were quantitatively assessed by comparing the lesions with their counterparts on T2-weighted images, apparent diffusion coefficient (ADC) maps, and contrast-enhanced T1-weighted images. Electron microscopic findings in group 1 were compared with those in group 2. Qualitatively, MR images revealed two types of lesions. Type 1 lesions were hyperintense on diffusion-weighted images and hypointense of ADC maps. Type 2 lesions were isointense or mildly hyperintense on diffusion-weighted images and isointense on ADC maps. Quantitatively, the signal intensity rations of type 1 lesions in group 2 specimens were significantly higher on T2-weighted images (P=.013)/(P=.027) and lower on ADC maps compared with those of group 1. Electron microscopy of type 1 lesions in both groups revealed more prominent widening of the perivascular space and swelling of the neural cells in groups 1. MR and electron microscopic data on cerebral fat embolism induced by either triolein or oleic acid revealed characteristics suggestive of both vasogenic and cytotoxic edema in the hyperacute stage. Tissue damage appeared more severe in the oleic acid group than in the triolein group.

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Advanced MRI for Pediatric Brain Tumors with Emphasis on Clinical Benefits

  • Goo, Hyun Woo;Ra, Young-Shin
    • Korean Journal of Radiology
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    • v.18 no.1
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    • pp.194-207
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    • 2017
  • Conventional anatomic brain MRI is often limited in evaluating pediatric brain tumors, the most common solid tumors and a leading cause of death in children. Advanced brain MRI techniques have great potential to improve diagnostic performance in children with brain tumors and overcome diagnostic pitfalls resulting from diverse tumor pathologies as well as nonspecific or overlapped imaging findings. Advanced MRI techniques used for evaluating pediatric brain tumors include diffusion-weighted imaging, diffusion tensor imaging, functional MRI, perfusion imaging, spectroscopy, susceptibility-weighted imaging, and chemical exchange saturation transfer imaging. Because pediatric brain tumors differ from adult counterparts in various aspects, MRI protocols should be designed to achieve maximal clinical benefits in pediatric brain tumors. In this study, we review advanced MRI techniques and interpretation algorithms for pediatric brain tumors.

Computed Diffusion-Weighted Imaging in Prostate Cancer: Basics, Advantages, Cautions, and Future Prospects

  • Ueno, Yoshiko R.;Tamada, Tsutomu;Takahashi, Satoru;Tanaka, Utaru;Sofue, Keitaro;Kanda, Tomonori;Nogami, Munenobu;Ohno, Yoshiharu;Hinata, Nobuyuki;Fujisawa, Masato;Murakami, Takamichi
    • Korean Journal of Radiology
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    • v.19 no.5
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    • pp.832-837
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    • 2018
  • Computed diffusion-weighted MRI is a recently proposed post-processing technique that produces b-value images from diffusion-weighted imaging (DWI), acquired using at least two different b-values. This article presents an argument for computed DWI for prostate cancer by viewing four aspects of DWI: fundamentals, image quality and diagnostic performance, computing procedures, and future uses.

Serial Magnetic Resonance Images of a Right Middle Cerebral Artery Infarction : Persistent Hyperintensity on Diffusion-Weighted MRI Over 8 Months

  • Son, Seung-Nam;Choi, Dae-Seob;Choi, Nack-Cheon;Lim, Byeong-Hoon
    • Journal of Korean Neurosurgical Society
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    • v.50 no.4
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    • pp.388-391
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    • 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.

Bone Involvement of Diffuse Large B Cell Lymphoma (DLBCL) Showing Unusual Manifestations Mimicking Chronic Osteomyelitis in a 58-Year-Old Man: Case Report and Clinical Application of Diffusion Weighted Magnetic Resonance Imaging

  • Lee, Kyung Ryeol;Maeng, Young Hee
    • Investigative Magnetic Resonance Imaging
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    • v.23 no.3
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    • pp.270-275
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    • 2019
  • This study presents a case of diffuse large B cell lymphoma (DLBCL) in a 58-year-old man showing unusual manifestations mimicking chronic osteomyelitis. In this case review, we describe the imaging findings of DLBCL which mimics chronic osteomyelitis and review existing reports regarding the differential diagnosis of bone involvement of lymphoma and osteomyelitis through imaging and laboratory findings and diffusion-weighted magnetic resonance imaging (DWI) such as the advanced MRI sequence.

Assessment of Diffusion-Weighted Imaging-FLAIR Mismatch: Comparison between Conventional FLAIR versus Shorter-Repetition-Time FLAIR at 3T

  • Goh, Byeong Ho;Kim, Eung Yeop
    • Investigative Magnetic Resonance Imaging
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    • v.20 no.2
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    • pp.88-94
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    • 2016
  • Purpose: Fluid-attenuated inversion recovery (FLAIR) imaging can be obtained faster with shorter repletion time (TR), but it gets noisier. We hypothesized that shorter-TR FLAIR obtained at 3 tesla (3T) with a 32-channel coil may be comparable to conventional FLAIR. The aim of this study was to compare the diagnostic value between conventional FLAIR (TR = 9000 ms, FLAIR9000) and shorter-TR FLAIR (TR = 6000 ms, FLAIR6000) at 3T in terms of diffusion-weighted imaging-FLAIR mismatch. Materials and Methods: We recruited 184 patients with acute ischemic stroke (28 patients < 4.5 hours) who had undergone 5-mm diffusion-weighted imaging (DWI) and two successive 5-mm FLAIR images (no gap; in-plane resolution, $0.9{\times}0.9mm$) at 3T with a 32-channel coil. The acquisition times for FLAIR9000 and FLAIR6000 were 108 seconds (generalized autocalibrating partially parallel acquisitions [GRAPPA] = 2) and 60 seconds (GRAPPA = 3), respectively. Two radiologists independently assessed the paired imaging sets (DWI-FLAIR9000 and DWI-FLAIR6000) for the presence of matched hyperintense lesions on each FLAIR imaging. The signal intensity ratios (area of DWI lesion to contralateral normal-appearing region) on both FLAIR imaging sets were compared. Results: DWI-FLAIR9000 mismatch was present in 39 of 184 (21.2%) patients, which was perfectly the same on FLAIR6000. Three of 145 patients (2%) with DWI-matched lesions on FLAIR9000 had discrepancy on FLAIR6000, showing no significant difference (P > 0.05). Interobserver agreement was excellent for both DWI-FLAIR9000 and DWI-FLAIR6000 (k = 0.904 and 0.883, respectively). Between the two FLAIR imaging sets, there was no significant difference of signal intensity ratio (mean, standard deviation; $1.25{\pm}0.20$; $1.24{\pm}0.20$, respectively) (P > 0.05). Conclusion: For the determination of mismatch or match between DWI and FLAIR imaging, there is no significant difference between FLAIR9000 and FLAIR6000 at 3T with a 32-channel coil.

Evaluation of Treatment Response Using Diffusion-Weighted MAI in Metastatic Spines (척추 전이암에서 확산강조 자기공명 영상을 이용한 치료반응의 평가)

  • Lee, Jang-Jin;Shin, Sei-One
    • Yeungnam University Journal of Medicine
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    • v.18 no.1
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    • pp.30-38
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    • 2001
  • Background: The purpose of this study was to evaluate the usefulness of diffusion-weighted magnetic resonance imaging for monitoring the response to radiation therapy in metastatic bone marrow of the spines. Materials and Methods: Twenty-one patients with metastatic bone marrow of the spines were examined with MRI. Diffusion-weighted and spin-echo MRI were performed in 10 patients before and after radiation therapy with or without systemic chemotherapy, and performed in 11 patients after radiation therapy alone. Follow up spin-echo and diffusion-weighted MRI were obtained at 1 to 6 months after radiation therapy according to patients' condition. The diffusion-weighted imaging sequence was based on reversed fast imaging with steady-state precession (PSIF). Signal intensity changes of the metastatic bone marrows before and after radiation therapy on conventional spin-echo sequence MRI and diffusion-weighted MRI were evaluated. Bone marrow contrast ratios and signal-to-noise ratios before and after radiation therapy of diffusion- weighted MRI were analyzed. Results: All metastatic bone marrow of the spinal bodies were hyperintense to normal bone marrow of the spinal bodies on pretreatment diffusion-weighted MRI and positive bone marrow contrast ratios(p<0.001), and hypointense to normal spinal bodies on posttreatment diffusion-weighted MRI and negative bone marrow contrast ratios(p<0.001). The signal to noise ratios after treatment decreased comparing with those of pretreatment. Decreased signal intensity of the metastatic bone marrows on diffusion-weighted MRI began to be observed at average more than one month after the initiation of the radiation therapy. Conclusion: These results suggest that diffusion-weighted MRI would be an excellent method for monitoring the response to therapy of metastatic bone marrow of the spinal bodies, however, must be investigated in a larger series of patients with longer follow up period.

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Quantitative and Qualitative Evaluation of Brain Diffusion Weighted Magnetic Resonance Imaging: Comparision with 1.5 T and 3.0 T Units (뇌 확산강조 자기공명영상에 대한 정량적, 성적 평가: 1.5 T와 3.0 T 기기 비교)

  • Goo, Eun-Hoe;Dong, Kyung-Rae
    • Journal of Radiation Industry
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    • v.10 no.4
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    • pp.227-230
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    • 2016
  • DWI of biological effects are independent of magnetic field strength in various regions. High field strength, however, does affect the signal to noise ratio (SNR) and artifacts of diffusion weighted imaging (DWI) images, which ultimately will influence the quantitative of diffusion imaging. In this study, the effects of field strength on DWI are reviewed. The effects of the diseases also are discussed. Comparing DWI in cerebellum, WM, GM, Hyperacute region measurements both as a function of field strength (1.5T and 3.0T). Overall, the SNR of the DWI roughly doubled going from 1.5 T to 3.0 T. In summary, DWI studies at 3.0 T is provided significantly improved DWI measurements relative to studies at 1.5T.

Transient global amnesia associated with multiple lesions in the corpus callosum and hippocampus

  • Kim, Jin-Ah;Min, Young Gi;Koo, Dae Lim
    • Annals of Clinical Neurophysiology
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    • v.21 no.2
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    • pp.102-104
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    • 2019
  • Transient global amnesia is a syndrome of temporary loss of short-term memory and is not accompanied by any other neurological deficit. Diffusion-weighted imaging is useful to improve the diagnostic accuracy of transient global amnesia. We report a 68-year-old woman with multiple lesions on diffusion-weighted imaging in the right corpus callosum and left hippocampus. To the best of our knowledge, this is the first case of a diffusion-weighted imaging lesion in the body portion of the corpus callosum.

Development of the Line Scan Diffusion Weighted Imaging at Low Tesla Magnetic Resonance Imaging System (저자장 자기공명영상시스템에서 선주사확산강조영상기법 개발)

  • Hong, Cheol-Pyo;Lee, Dong-Hoon;Lee, Do-Wan;Lee, Man-Woo;Paek, Mun-Young;Han, Bong-Soo
    • Journal of the Korean Society of Radiology
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    • v.2 no.2
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    • pp.31-38
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    • 2008
  • Line scan diffusion weighted imaging (LSDI) pulse sequence for 0.32 T magnetic resonance imaging (MRI) system was developed. In the LSDI pulse sequence, the imaging volume is formed by the intersection of the two perpendicular planes selected by the two slice-selective $\pi$/2-pulse and $\pi$-pulse and two diffusion sensitizing gradients placed on the both side of the refocusing $\pi$-pulse and the standard frequency encoding readout was followed. Since the maximum gradient amplitude for the MR system was 15 mT/m the maximum b value was $301.50s/mm^2$. Using the developed LSDI pulse sequence, the diffusion weighted images for the aqueous NaCl solution phantom and triacylglycerol solution phantom calculated from the line scan diffusion weighted images gives the same results within the standard error range (mean diffusivities = $963.90{\pm}79.83({\times}10^{-6}mm^2/s)$ at 0.32 T, $956.77{\pm}4.12({\times}10^{-6}mm^2/s)$ at 1.5 T) and the LSDI images were insensitive to the magnetic susceptibility difference and chemical shift.

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