• Journal of Magnetics
• /
• v.22 no.1
• /
• pp.146-149
• /
• 2017

In this study, we compared the standardized value of each signal intensity, the apparent diffusion coefficient (ADC) that digitizes the diffusion of water molecules, and the signal to noise ratio (SNR) using b value 0 400, 1400 ($s/mm^2$). From March 2013 to December 2013, patients with suspicion of simple compound fracture and metastatic spine cancer were included in the MR readout. We used a 1.5 Tesla Achieva MRI system and a Syn-Spine Coil. Sequence is a DWI SE-EPI sagittal (diffusion weighted imaging spin echo-echo planar imaging sagittal) image with b-factor ($s/mm^2$) 0, 400, 1400 were used. Data analysis showed ROI (Region of Interest) in diseased area with high SI (signal intensity) in diffusion-weighted image b value 0 ($s/mm^2$) Using the MRIcro program, each SI was calculated with images of b-value 0, 400, and 1400 ($s/mm^2$), ADC map was obtained using Metlab Software with each image of b-value, The ADC is obtained by applying the ROI to the same position. The standardized values ($SI_{400}/SI_0$, $SI_{400}/SI_0$) of simple compression fractures were $0.47{\pm}0.04$ and $0.23{\pm}0.03$ and the standardized values ($SI_{400}/SI_0$, $SI_{400}/SI_0$) of the metastatic spine were $0.57{\pm}0.07$ and $0.32{\pm}0.08$ And the standardized values of the two diseases were statistically significant (p < 0.05). The ADC ($mm^2/s$) for b value 400 ($s/mm^2$) and 1400 ($s/mm^2$) of the simple compression fracture disease site were $1.70{\pm}0.16$ and $0.93{\pm}0.28$ and $1.24{\pm}0.21$ and $0.80{\pm}0.15$ for the metastatic spine. The ADC ($mm^2/s$) for b value 400($s/mm^2$) was statistically significant (p < 0.05) but the ADC ($mm^2/s$) for b value 1400 (p > 0.05). In conclusion, multi - b value recognition of signal changes in diffusion - weighted imaging is very important for the diagnosis of various spinal diseases.

• Investigative Magnetic Resonance Imaging
• /
• v.20 no.4
• /
• 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.

• Investigative Magnetic Resonance Imaging
• /
• v.6 no.1
• /
• pp.21-27
• /
• 2002

Purpose : To evaluate diffusion-weighted imaging findings of intracerebral hematoma according to the time sequence. Materials and methods : Seventeen patients with intracerebral hematoma were studied. Diffusion weighted images using 1.5 tesla MRI machine were obtained with b-value of $1000{\;}sec/\textrm{mm}^2$. The patients were grouped as hyperacute stage(within 12 hours, 5 patients), acute stage(within 3 days, 4 patients), subacute stage(within 3 weeks, 4 patients), and chronic stage(after 3 weeks,4 patients). The signal intensities were analysed as bright, high, iso, low and dark at the central and peripheral portions of the hematoma in each stage, and compared with those of T2 and T1 weighted images. Results : The signal intensities of the central and peripheral portion of the intracerebral hematoma on diffusion-weighted images were high and dark in hyperacute stage, dark and high-bright in acute stage, and high-bright and dark in subacute and chronic stages. The patterns of signal change of hematoma on diffusion-weighted image according to the time sequence were similar to those on T2-weighted image, but changed early and prominently. Conclusion : The intracerebral hematoma on diffusion-weighted image showed unique central and peripheral signal intensity according to the time sequence. Central portions show high to bright signals in hyperacute, subacute and chronic stage, and dark signal in acute stage, and peripheral portions show dark signals in hyperacute, subacute and chronic stage, and high to bright signal in acute stage.

• Journal of Magnetics
• /
• v.17 no.2
• /
• pp.153-157
• /
• 2012

This study evaluated the ability of Diffusion-Weight Image (DWI), which is one of pulse sequences used in MRI based on the T2 weighted images, to detect samples placed within phantoms according to their size. Two identically sized phantoms, which could be inserted into the breast coil bilaterally, were prepared. Five samples with different sizes were placed in the phantoms, and the T2 weighted images and DWI were obtained. The Breast 2 channel coil of SIEMENS MAGNETOM Avanto 1.5 Tesla equipment was used for the experiments. 2D T2 weighted images were obtained using the following parameters: TR/TE = 6700/74 msec, Thickness/gap = 5/1 mm, Inversion Time (TI) = 130 ms, and matrix = $224{\times}448$. The parameters of DWI were that TR/TE = 8100/90 msec, Thickness/gap = 5/1 mm, matrix = $128{\times}128$, Inversion Time = 185 ms, and b-value = 0, 100, 300, 600, 1000 s/mm. The ratio of the sample volume on DWI compared to the T2 weighted images, which show excellent ability to detect lesions on MR images, was presented as the mean b-value. The measured b-value of the samples was obtained: 0.5${\times}$0.5 cm=0.33/0.34 square ${\times}$ cm (103%), 1${\times}$1 cm=1.28/1.25 square ${\times}$ cm (102.4%), 1.5${\times}$1.5 cm = 2.28/2.67 square ${\times}$ cm (85.39%), 2${\times}$2 cm=3.56/4.08 square ${\times}$ cm (87.25%), and 2.5${\times}$2.5 cm=7.53/8.77 square ${\times}$ cm (85.86%). In conclusion, the detection ability by the size of a sample was measured to be over 85% compared to T2 weighted image, but the detection ability of DWI was relatively lower than that of T2 weighted image.

• Biomedical Science Letters
• /
• v.11 no.3
• /
• pp.307-310
• /
• 2005

Cerebral ischemia results in neuronal changes in remote areas that have fiber connections with the ischemic area. The aim of this study was to investigate the nigral changes by examining the correlation between the apparent diffusion coefficient (ADC) and the tissue structure. Sprague-Dawley rats were subjected to middle cerebral artery occlusion. Four days after the occlusion, when T2-weighted images revealed the presence of an area of high signal intensity in the ipsilateral substantia nigra, and the ADCs were calculated and imaged. Histopathologic examination by both light and electron microscopy was performed on day 4 after surgery. This finding was consistent with the high signal intensity seen on T2-weighted and diffusion-weighted images, as well as with the ADC reduction, but we did not expect to observe uniform ADC reduction attributable mainly to astrocytic swelling in the perivascular end-feet.

• Journal of Radiation Industry
• /
• v.10 no.4
• /
• pp.227-230
• /
• 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.

• Korean Journal of Radiology
• /
• v.21 no.1
• /
• pp.77-87
• /
• 2020

Objective: To assess the feasibility of simultaneous multislice-accelerated diffusion-weighted imaging (SMS-DWI) of the rectum in comparison with conventional DWI (C-DWI) in rectal cancer patients. Materials and Methods: This study included 65 patients with initially-diagnosed rectal cancer. All patients underwent C-DWI and SMS-DWI with acceleration factors of 2 and 3 (SMS2-DWI and SMS3-DWI, respectively) using a 3T scanner. Acquisition times of the three DWI sequences were measured. Image quality in the three DWI sequences was reviewed by two independent radiologists using a 4-point Likert scale and subsequently compared using the Friedman test. Apparent diffusion coefficient (ADC) values for rectal cancer and the normal rectal wall were compared among the three sequences using repeated measures analysis of variance. Results: Acquisition times using C-DWI, SMS2-DWI, and SMS3-DWI were 173 seconds, 107 seconds, (38.2% shorter than C-DWI), and 77 seconds (55.5% shorter than C-DWI), respectively. For all image quality parameters other than distortion (margin sharpness, artifact, lesion conspicuity, and overall image quality), C-DWI and SMS2-DWI yielded better results than did SMS3-DWI (Ps < 0.001), with no significant differences observed between C-DWI and SMS2-DWI (Ps ≥ 0.054). ADC values of rectal cancer (p = 0.943) and normal rectal wall (p = 0.360) were not significantly different among C-DWI, SMS2-DWI, and SMS3-DWI. Conclusion: SMS-DWI using an acceleration factor of 2 is feasible for rectal MRI resulting in substantial reductions in acquisition time while maintaining diagnostic image quality and similar ADC values to those of C-DWI.

• Korean Journal of Radiology
• /
• v.22 no.1
• /
• pp.9-22
• /
• 2021

Diffusion-weighted (DW) magnetic resonance imaging (MRI) is a rapid, unenhanced imaging technique that measures the motion of water molecules within tissues and provides information regarding the cell density and tissue microstructure. DW MRI has demonstrated the potential to improve the specificity of breast MRI, facilitate the evaluation of tumor response to neoadjuvant chemotherapy and can be employed in unenhanced MRI screening. However, standardization of the acquisition and interpretation of DW MRI is challenging. Recently, the European Society of Breast Radiology issued a consensus statement, which described the acquisition parameters and interpretation of DW MRI. The current article describes the basic principles, standardized acquisition protocols and interpretation guidelines, and the clinical applications of DW MRI in breast imaging.

• Journal of the Korean Society of Radiology
• /
• v.10 no.7
• /
• pp.545-550
• /
• 2016

The purpose of this study is to improve the mapping between functional image and conventional image by using rectangular FOV technique. Diffusion weighted imaging which is widely used for stroke was acquired by reducing the FOV and compared each Apparent Diffusion Coefficient(ADC). As a result, there is no significant difference of each ADC value in one-way-anova analysis and post-hoc analysis. Thus, Mismatching problem may be improved by matching the FOV with rectangular FOV technique because there is no difference in ADC values.

• Journal of Korean Neurosurgical Society
• /
• v.41 no.6
• /
• pp.371-376
• /
• 2007

Objective : The aim of this study was to investigate the usefulness of diffusion-weighted imaging [DWI] and apparent diffusion coefficiency [ADC] in distinguishing brain abscesses from cystic or necrotic brain tumors, which are difficult to be differentiated by conventional magnetic resonance imaging techniques. Methods : Seven patients with brain abscesses and ten patients with cystic brain tumors were studied from September 2003 to October 2005. Abscess, subdural empyema and ventriculitis were categorized to the abscess group and cystic or necrotic brain gliomas or metastatic brain tumors into the tumor group. Preoperative magnetic resonance images were performed in all patients and diffusion-weighted images and apparent diffusion coefficiency values of lesions were calculated directly from software of 1.5 tesla MRI [General Electrics, USA]. The ratio of the ADC of the lesion to contralateral regional ADC was also measured [relative ADC, rADC]. Results : The average ADC value of pyogenic abscesses group was $0.82+/-0.14{\times}10^{-3}\;[mean+/-S.D.]\;mm^2/s$ and mean rADC was 0.75. Cystic or necrotic areas had high ADC values [$2.49+/-0.79{\times}10^{-3}\;mm^2/s$, mean rADC=2.14]. ADC and rADC values of abscesses group showed about three times lower values than those of cystic or necrotic tumor group. Conclusion : This study results based on numerical comparison of signal intensities and quantitative analysis to distinguish between brain abscess and cystic or necrotic tumor, DWI and ADC mapping are thought to be very useful diagnostic tools.