• Korean Journal of Radiology
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• v.2 no.4
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• pp.192-196
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• 2001

Objective: To compare conventional and diffusion-weighted MR imaging in terms of their depiction of the abnormalities occurring in Creutzfeldt-Jakob disease. Materials and Methods: We retrospectively analyzed the findings of conventional (T2-weighted and fluid-attenuated inversion recovery) and diffusion-weighted MR imaging in four patients with biopsy-proven Creutzfeldt-Jakob disease. The signal intensity of the lesion was classified by visual assessment as markedly high, slightly high, or isointense, relative to normal brain parenchyma. Results: Both conventional and diffusion-weighted MR images demonstrated bilateral high signal intensity in the basal ganglia in all four patients. Cortical lesions were observed on diffusion-weighted MR images in all four, and on fluid-attenuated inversion recovery MR images in one, but in no patient on T2-weighted images. Conventional MR images showed slightly high signal intensity in all lesions, while diffusion-weighted images showed markedly high signal intensity in most. Conclusion: Diffusion-weighted MR imaging is more sensitive than its conventional counterpart in the depiction of Creutzfeldt-Jakob disease, and permits better detection of the lesion in both the cerebral cortices and basal ganglia.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.15-19
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• 2001

지난 10년간 신경계의 MR영상은 컴퓨터를 비롯한 하드웨어적인 발달에 힘입어 functional imaging, perfusion imaging, diffusion imaging, MR spectroscopy, MR angiography 등의 분야에서 괄목한 만한 성장이 있었다. 지난 2001년 4월 국제자기공명의과학회 (ISMRM) 학술대회에 약 2300개의 논문이 발표되었으며 이 중 신경계와 관련된 논문의 수는 저자가 파악하기에 약 500개 정도이었다. 매년 수많은 논문이 발표되고 있으나 이 중 기초 또는 임상의학적으로 유용한 논문만이 후속 연구로 연결되어 궁극적으로 많은 사람들이 활용할 수 있게 되고 있다. 따라서 지난 수 년 동안의 연구 동향을 모두 follow-up하는 것은 무의미하며, 이 중 functional, perfusion, diffusion imaging을 중심으로 이들 영상 기법의 기술적 측면과 적용 분야를 알아보고자 한다.

• Investigative Magnetic Resonance Imaging
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• v.6 no.2
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• pp.158-165
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• 2002

Purpose : To evaluate the effect of Gd-DTPA on signal intensity of diffusion-weighted magnetic resonance(MR) image and apparent diffuse coefficient (ADC) in dog brain with hype racute stroke. Materials and methods : Experimental canine model of hyperacute cerebral infarction was made by selective intraarterial embolization with particulate embolic material. Diffusion-weighted MR imaging was performed in five dogs at 1 hour after the embolization of internal carotid artery. After intravenous bolus injection of Gd- DTPA, additional 11 diffusion-weighted MR images were serially obtained from 2 minutes to 90 minutes after injection in each dog. The author evaluated findings of hyperacute cerebral infarction on diffusion-weighted MR imaging, and calculated mean signal intensity and mean ADC in infarcted region and contralateral normal region. Statistical analysis of mean signal intensity, mean ADC and contrast-noise ratio before and after Gd-DTPA injection was performed. Results : Hyperacute cerebral infarction developed in all five dogs on diffusion-weighted MR images obtained 1 hour after embolization. The area of hyperacute infarction had steady increase in signal intensity on diffusion-weighted MR image and decrease in ADC. In normal perfusion area, decrease in signal intensity was observed at 2 minutes the Gd-DTPA injection, whereas ADC did not changed. Conclusion : Intravenous injection of Gd-DTPA had no influence on ADC in both hyperacute infarction and normally perfused are a, but caused initial transient signal reduction in normally perfused area on diffusion-weighted MR image due to susceptibility effect of Gd-DTPA. It is important to calculate ADC in evaluating the effect of diffusion after injection of Gd-DTPA.

• Investigative Magnetic Resonance Imaging
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• v.18 no.2
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• pp.176-181
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• 2014

Primary non-Hodgkin lymphoma (NHL) of the breast is a very rare disease, and the mammographic and ultrasonographic findings of breast lymphoma are variable. There are several reports of magnetic resonance (MR) imaging findings in patients with breast lymphomas; however, few reports have described the findings observed on MR spectroscopy or the features of diffusion weighted (DW) imaging. The authors report the findings of classical MR imaging, MR spectroscopy and DW imaging of a 48-year-old woman and a 40-year-old woman with primary non-Hodgkin's lymphoma of breasts. Mammography and breast ultrasonography revealed a mass with circumscribed margin. The mass showed strong enhancement after contrast injection on MR imaging. DW imaging showed reduced diffusion and high-amplitude choline (Cho) peak at 3.22 ppm was detected by single voxel MR spectroscopy which was consistent with malignancy.

• Journal of Korean Neurosurgical Society
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• v.43 no.6
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• pp.275-280
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• 2008

Objective : In order to assess the incidence of thromboembolic events and their clinical presentations, the present study prospectively examined routine brain magnetic resonance images (MRI) taken within 48 hours after a coil embolization of cerebral aneurysms. Methods : From January 2006 to January 2008, 163 cases of coil embolization of cerebral aneurysm were performed along with routine brain MRI, including diffusion-weighted magnetic resonance (DW-MR) imaging, within 48 hours after the embolization of the aneurysm to detect the silent thromboembolic events regardless of any neurological changes. If any neurological changes were observed, an immediate brain MRI follow-up was performed. High-signal-intensity lesions in the DW-MR images were considered as acute thromboembolic events and the number and locations of the lesions were also recorded. Results : Among the 163 coil embolization cases, 98(60.1%) showed high-signal intensities in the DW-MR imaging follow-up, 66 cases (67.0%) involved the eloquent area and only 6cases (6.0%) showed focal neurological symptoms correlated to the DW-MR findings. The incidence of DW-MR lesions was higher in older patients (${\geq}60$ yrs) when compared to younger patients (<60 yrs) (p=0.002, odd's ratio=1.043). The older patients also showed a higher incidence of abnormal DW-MR signals in aneurysm-unrelated lesions (p=0.0003, odd's ratio=5.078). Conclusion : The incidence of symptomatic thromboembolic attacks after coil embolization of the cerebral aneurysm was found to be lower than that reported in previous studies. While DW-MR imaging revealed a higher number of thromboembolic events, most of these were clinically silent and transient and showed favorable clinical outcomes. However, the incidence of DW-MR abnormalities was higher in older patients, along with unpredictable thromboembolic events on DW-MR images. Thus, in order to provide adequate and timely treatment and to minimize neurological sequelae, a routine DW-MR follow-up after coil embolization of cerebral aneurysms might be helpful, especially in older patients.

• Journal of Veterinary Clinics
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• v.37 no.6
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• pp.317-323
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• 2020

The aims of this study were to describe the appearance and size of the normal canine prostate using magnetic resonance (MR) imaging and to calculate the apparent diffusion coefficient (ADC) values. MR images were obtained from seven intact male beagle dogs using a 1.5 T MR unit. The sequences included pre- and post-contrast T1- and T2-weighted imaging with and without fat saturation. The signal intensity of the prostate was compared with the adjacent musculature, fat, and urine in the urinary bladder. We recorded the mean prostatic length, width, and height and the length of the sixth lumbar vertebral body (L6). In addition, the prostatic length (rL), width (rW), and height (rH) ratios to L6 were calculated. Diffusion-weighted images of the prostate were obtained and ADC values were calculated. The prostate was bilobed and oval-shaped, homogenous on T1-weighted images, and heterogeneous with radiating lines on T2-weighted images. Post-contrast T1-weighted sequences showed contrast enhancement of the central and radiating striations. The prostatic capsule was clearly identified on post-contrast T1-weighted images with fat saturation. The ADC values were 1.72-2.04 × 10-3mm2/sec (mean, 1.88 × 10-3mm2/sec). Knowledge of the normal appearance of the prostate on MR images is essential to assess prostatic diseases in dogs.

• 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.

• Journal of Magnetics
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• v.17 no.3
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• pp.219-224
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• 2012

In the present study, changes in signal-to-noise ratio (SNR) and apparent diffusion coefficient (ADC) of the diffusion-weighted images in the normal livers were investigated using changes in b values in 1.5 T MR (magnetic resonance) instruments. Respective diffusion-weighted images and ADC map images were obtained from 20 healthy individuals by increasing b values from 50 to 400 and 800 $s/mm^2$ using 1.5T MR scanner between January 2011 and November 2011. At each ADC map image obtained at each b value, ADCs in the right hepatic lobe, spleen and kidney were measured. As a result, ADCs of the right hepatic lobe, spleen and kidney have gradually decreased in the diffusion-weighted images in accordance with the reduced b value. This outcome may be used as preliminary data for applications to various abdominal diseases.

• Progress in Medical Physics
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• v.21 no.1
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• pp.52-59
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• 2010

To examine among patients with vertebral compression fracture the extent to which signal-to-noise ratio (SNR) and Apparent Diffusion Coefficient (ADC) values at the lumbar vertebral compression fracture site vary on diffusion-weighted MR images according to varying b values on the 1.5T MR device. Diffusion-weighted MR images of 30 patients with compression fracture due to chronic osteoporosis who underwent vertebral MRI from Jan. 2008 to Nov. 2009 were respectively obtained using a 1.5-T MR scanner with the b values increased from 400, 600, 800, 1,000 to $1,200\;s/mm^2$. For diffusion-weighted MR images with different b values, the signal-to-noise ratio (SNR) was assessed at three sites: the site of compression fracture of the lumbar vertebral body at L1 to L5, and both the upper and lower discs of the said fracture site, while for ADC map images with different b values, the SNR and ADC were respectively assessed at those three sites. As a quantitative analysis, diffusion-weighted MR images and ADC map images with b value of $400\;s/mm^2$ (the base b values) were respectively compared with the corresponding images with each different b value. As far as qualitative analysis is concerned, for both diffusion-weighted MR and ADC map images with b value of $400\;s/mm^2$, the extent to which signal intensity values obtained at the site of compression fracture of the lumbar vertebral body at L1 to L5 vary according to the increasing b values were examined. The quantitative analysis found that for both diffusion-weighted MR and ADC map images, as the b values increased, the SNR were relatively lowered at all the three sites, compared to the base b value. Also, it was found that as the b values increased, ADC valueswere relatively lowered at all the three sites on ADC map images. On the other hand, the qualitative analysis found that as the b values increased to more than $400\;s/mm^2$, the signal intensity gradually decreased at all the sites, while at the levels of more than $1,000\;s/mm^2$, severe image noises appeared at all of the three sites. In addition, higher signal intensity was found at the site of compression fracture of the lumbar vertebral body than at the discs. Findings showed that with the b value being increased, both the signal-to-noise ratio (SNR) and Apparent Diffusion Coefficient (ADC) values gradually decreased at all the sites of the lumbar vertebral compression fracture and both the upper and lower discs of the fracture site, suggesting that there is a possibility of a wider range of applications to assessment of various vertebral pathologies by utilizing multi b values in the diffusion-weighted MRI examination.

• Journal of the Korean Society of Radiology
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• v.85 no.3
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• pp.607-617
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• 2024

Purpose Recent studies have demonstrated the usefulness of diffusion-weighted MR neurography (DW MRN) for assessing nerve roots. This study aimed to evaluate the utility of DW MRN with a unidirectional motion-probing gradient (MPG) for the lumbar nerve roots at 1.5T MR. Materials and Methods Sixty-four lumbar spine MRI scans with DW MRN using anteroposterior unidirectional MPG were retrospectively analyzed. Any changes in the 512 lumbar spinal nerve roots from L3 to S1 were evaluated using T2-weighted imaging (T2WI), contrast-enhanced T1-weighted imaging (CE T1WI), and DW MRN, with agreement and correlation analysis. Results T2WI revealed compression of 78 nerve roots, and CE T1WI revealed 52 instances of nerve root enhancement. Sixty-seven nerve roots showed swelling and hyperintensity on DW MRN. A total of 42 nerve roots showed changes in the CE T1WI and DW MRN sequences. Moderate to substantial agreement and moderate positive correlation were observed between DW MRN and CE T1WI, as well as DW MRN and T2WI (κ = 0.59-0.65, ρ = 0.600-0.653). Conclusion DW MRN with unidirectional anteroposterior MPG can help evaluate neuritisrelated changes in spinal nerve roots and could serve as a sequence capable of complementing or substituting gadolinium CE imaging.