• Title/Summary/Keyword: Diffusion weighted image(DWI)

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Analysis of Image Distortion on Magnetic Resonance Diffusion Weighted Imaging

  • Cho, Ah Rang;Lee, Hae Kag;Yoo, Heung Joon;Park, Cheol-Soo
    • Journal of Magnetics
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    • v.20 no.4
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    • pp.381-386
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    • 2015
  • The purpose of this study is to improve diagnostic efficiency of clinical study by setting up guidelines for more precise examination with a comparative analysis of signal intensity and image distortion depending on the location of X axial of object when performing magnetic resonance diffusion weighted imaging (MR DWI) examination. We arranged the self-produced phantom with a 45 mm of interval from the core of 44 regent bottles that have a 16 mm of external diameter and 55 mm of height, and were placed in 4 rows and 11 columns in an acrylic box. We also filled up water and margarine to portrait the fat. We used 3T Skyra and 18 Channel Body array coil. We also obtained the coronal image with the direction of RL (right to left) by using scan slice thinkness 3 mm, slice gap: 0mm, field of view (FOV): $450{\times}450mm^2$, repetition time (TR): 5000 ms, echo time (TE): 73/118 ms, Matrix: $126{\times}126$, slice number: 15, scan time: 9 min 45sec, number of excitations (NEX): 3, phase encoding as a diffusion-weighted imaging parameter. In order to scan, we set b-value to $0s/mm^2$, $400s/mm^2$, and $1,400s/mm^2$, and obtained T2 fat saturation image. Then we did a comparative analysis on the differences between image distortion and signal intensity depending on the location of X axial based on iso-center of patient's table. We used "Image J" as a comparative analysis programme, and used SPSS v18.0 as a statistic programme. There was not much difference between image distortion and signal intensity on fat and water from T2 fat saturation image. But, the average value depends on the location of X axial was statistically significant (p < 0.05). From DWI image, when b-value was 0 and 400, there was no significant difference up to $2^{nd}$ columns right to left from the core of patient's table, however, there was a decline in signal intensity and image distortion from the $3^{rd}$ columns and they started to decrease rapidly at the $4^{th}$ columns. When b-value was 1,400, there was not much difference between the $1^{st}$ row right to left from the core of patient's table, however, image distortion started to appear from the $2^{nd}$ columns with no change in signal intensity, the signal was getting decreased from the $3^{rd}$ columns, and both signal intensity and image distortion started to get decreased rapidly. At this moment, the reagent bottles from outside out of 11 reagent bottles were not verified from the image, and only 9 reagent bottles were verified. However, it was not possible to verify anything from the $5^{th}$ columns. But, the average value depends on the location of X axial was statistically significant. On T2 FS image, there was a significant decline in image distortion and signal intensity over 180mm from the core of patient's table. On diffusion-weighted image, there was a significant decline in image distortion and signal intensity over 90 mm, and they became unverifiable over 180 mm. Therefore, we should make an image that has a diagnostic value from examinations that are hard to locate patient's position.

Isolated Distal leg Weakness due to a Small Cerebral Infarction Masquerading as a Spinal Lesion

  • Han, In-Bo;Ahn, Jung-Yang;Chung, Young-Sun;Chung, Sang-Sup
    • Journal of Korean Neurosurgical Society
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    • v.41 no.3
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    • pp.182-185
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    • 2007
  • Acute stroke with isolated monoparesis manifesting as distal weakness of a single lower extremity has rarely been described. We report two patients with small cortical infarction who had distal weakness of a single lower extremity. In both cases, diffusion-weighted image [DWI] was used to detect small lesions in the contralateral cortex. These cases illustrate that small cortical infarction can cause isolated monoparesis limited to distal part of the leg and it may be misdiagnosed as spinal lesions, especially when lower back pain and transient sensory symptoms are accompanied. In case of the abrupt onset of weakness limited to one lower limb, the possibility of stroke should be considered and careful attention to identify cortical lesions using magnetic resonance imaging, especially DWI is required.

Individual approach in the recanalization treatment of the acute ischemic brain stroke according to the various MR findings in hyperacute stage

  • Y. Jang;Lee, D.;Kim, H.;Lee, J.;Park, C.G.;Lee, H.K.;Kim, S.;D. Suh
    • Proceedings of the KSMRM Conference
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    • 2003.10a
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    • pp.98-98
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    • 2003
  • We will present various MR findings of hyperacute ischemic stroke with our own experiences in the management of the patients according to the findings. 대상 및 방법: A total of 441 patients were underwent 'acute stroke MR' imaging protocol between Mar. 2001 and Jun. 2003. The protocol included initial T2-weighted image (WI), diffusion WI (DWI, b=2000), time-of-flight (TOF) MR angiography (MRA), and pefusion WI(PWI), and follow-up T2WI, DWI, TOF MRA, and neck vessel contrast-enhanced MRA obtained three to five days after the insult. Among them, we retrospectively reviewed the MR findings and clinical courses of 193 patients with anterior circulation territorial infarction. Those ICA and MCA lesions were divided into six and five groups respectively according to the level and mechanism of the occlusion. PWI findings can be another factor in the management planning.

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Perfusion MR Imaging of Seizure-related Cerebral Cortical Lesion: A Case Report (발작에 의한 대뇌피질 병변의 관류 MR영상: 증례 보고)

  • Seo, Hyemin;Choi, Dae Seob;Shin, Hwa Seon;Son, Seungnam
    • Investigative Magnetic Resonance Imaging
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    • v.17 no.4
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    • pp.312-315
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    • 2013
  • When cerebral cortical hyperintensities on diffusion-weighted image are seen in patients with suspected acute stroke accompanying seizure, it is necessary to differentiate whether they are caused by infarction or seizure-related change. We report a case of seizure-related cortical hypertensities in a patient with suspected acute infarction. With perfusion MR imaging, we could differentiate from acute infarction.

The Role of Double Inversion Recovery Imaging in Acute Ischemic Stroke

  • Choi, Na Young;Park, Soonchan;Lee, Chung Min;Ryu, Chang-Woo;Jahng, Geon-Ho
    • Investigative Magnetic Resonance Imaging
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    • v.23 no.3
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    • pp.210-219
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    • 2019
  • Purpose: The purpose of this study was to investigate if double inversion recovery (DIR) imaging can have a role in the evaluation of brain ischemia, compared with diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) imaging. Materials and Methods: Sixty-seven patients within 48 hours of onset, underwent MRI scans with FLAIR, DWI with b-value of 0 (B0) and $1000s/mm^2$, and DIR sequences. Patients were categorized into four groups: within three hours, three to six hours, six to 24 hours, and 24 to 48 hours after onset. Lesion-to-normal ratio (LNR) value was calculated and compared among all sequences within each group, by the Friedman test and conducted among all groups, for each sequence by the Kruskal-Wallis test. In qualitative assessment, signal intensity changes of DIR, B0, and FLAIR based on similarity with DWI and image quality of each sequence, were graded on a 3-point scale, respectively. Scores for detectability of lesions were compared by the McNemar's test. Results: LNR values from DWI were higher than DIR, but not statistically significant in all groups (P > 0.05). LNR values of DIR were significantly higher than FLAIR within 24 hours of onset (P < 0.05). LNR values were significantly different between, before, and after six hours onset time for DIR (P = 0.016), B0 (P = 0.008), and FLAIR (P = 0.018) but not for DWI (P = 0.051). Qualitative analysis demonstrated that detectability of DIR was higher, compared to that of FLAIR within 4.5 hours and six hours of onset (P < 0.05). Also, the DWI quality score was lower than that of DIR, particularly relative to infratentorial lesions. Conclusion: DIR provides higher detectability of hyperacute brain ischemia than B0 and FLAIR, and does not suffer from susceptibility artifact, unlike DWI. So, DIR can be used to replace evaluation of the FLAIR-DWI mismatch.

A Study on the DWI and Pathologic Findings of Cancer Cells (암 세포주의 확산강조영상과 병리학적 관계에 관한 연구)

  • Seong, Jae-Gu;Lim, Cheong-Hwan
    • Journal of radiological science and technology
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    • v.34 no.3
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    • pp.239-244
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    • 2011
  • In this study, we evaluated diffusion weighted imaging (DWI) to investigate whether the DWI parameters can predict characteristic parameters on pathologic specimens of tumor or not. CFPAC-1 was injected subcutaneously on the back flank of athymic nude mice (n=13) then two tumors were initiated on each mouse (2${\times}$13=26 tumors). The mice were sacrificed to make specimen immediately after initial MR imaging then were compared with the MR image. A dedicated high-field (7T) small-animal MR scanner was used for image acquisitions. A T1 and T2 weighted axial image using RARE technique was acquired to measure the T2 values and tumor size. DWI MR was performed for calculating ADC values. To evaluate tumor cellularity and determine the levels of MVD, tumor cells were excised and processed for H-E staining and immunostaining using CD31. T2 values and ADC values were computed and analyzed for each half of the tumors and compared to the correlated specimens slide. Median ADC within each half of mass was compared to the cellularity and MVD in the correlated area of pathologic slide. The mean of ADC value is $0.7327{\times}10^{-3}$ $mm^2/s$ and standard deviation is $0.1075{\times}10^{-3}$ $mm^2/s$. There is a linear relationship between ADC value and tumor necrosis (R2=0.697, p< 0.001). DW image parameters including the ADC values can be utilized as surrogate markers to assess intratumoral neoangiogenesis and change of the internal structure of tumor cells.

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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Implementation of Regional Cerebral Blood Volume Map Using Perfusion Magnetic Resonance Image Process Algorithm (관류자기공명 영상처리 알고리즘을 이용한 대뇌 혈류량 맵의 구현)

  • Park Byung-Rae
    • The Journal of the Korea Contents Association
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    • v.5 no.5
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    • pp.296-304
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    • 2005
  • Quantitative analysis compare to dynamic characteristic change of the regional cerebral blood volume(rCBV) after development of cerebral fat embolism in cats using perfusion magnetic resonance(MR) Imaging. Twenty cats were used. Linoleic acid (n=11) were injected into the internal carotid artery using microcatheter through the transfemoral approach. Polyvinyl alcohol (Ivalon) (n=9) was injected as a control group. Perfusion MR images were obtained at 30 minutes and 2 hours after embolization, based on T2 and diffusion-weighted images. The data was time-to-signal intensity curve and ${\Delta}R_2^*$ curve were obtained continuously with the aid of home-maid image process algorithm and IDL(interactive data Banguage, USA) softwares. The ratios of rCBV increased significantly at 2 hours compared with those of 30 minutes (P<0.005). In conclusion, cerebral blood flow decreased in cerebral fat embolism immediately after embolization and recovered remarkably in time course. It is thought that clinically informations to dynamic characteristic change of the cerebral hemodynamics to the early finding in cerebral infarction by diffusion weighted imaging(DWI) and perfusion weighted imaging(PWI).

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Pre-operative Evaluation of Consistency in Intra-axial Brain Tumor with Diffusion-weighted Images (DWI) and Conventional MR Images (확산강조영상과 고식적 자기공명영상을 이용한 수술 전 축내 뇌종양의 경도 평가)

  • Oh, Moon-Sik;Ahn, Kook-Jin;Choi, Hyun-Seok;Jung, So-Lyung;Lee, Yoon-Joo;Kim, Bum-Soo
    • Investigative Magnetic Resonance Imaging
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    • v.15 no.2
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    • pp.102-109
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    • 2011
  • Purpose : To retrospectively evaluate the usefulness of diffusion-weighted images, ADC maps and conventional MR images for determination of brain tumor consistency. Materials and Methods : Twenty-three patients with brain tumor underwent MR examinations with T1, T2 and diffusion-weighted images. Regions of interest (ROIs) were drawn in the tumors, and the measured signal intensities (SI) were normalized with the contralateral side. We evaluated the correlation between SI ratios from various images and tumor consistency assessed at surgery. In three patients with both cystic and solid components, each component was evaluated independently. Qualitatively observed SIs were also correlated with tumor consistency. Results : Statistical analysis revealed significant correlation between tumor consistency and ADC ratio (r = -0.586, p = 0.002), SI ratios on T2-weighted images (r = -0.497, p = 0.010), and observed SIs on T2-weighted images (r = -0.461, p = 0.018). The relative ratio of ADC value correlated with tumor consistency most strongly. Conclusion : The measured ratio of ADC, SI ratio and observed SI grade on T2-weighted images can provide valuable information about the consistency of brain tumor.

3T DWIs with Different b-Values in Brain Tumors

  • 김대진;장기현;송인찬;권배주;한문희
    • Proceedings of the KSMRM Conference
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    • 2003.10a
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    • pp.24-24
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    • 2003
  • Purpose: It is known that diffusion-weighted MR imaging (DWI) is helpful in the evaluation of malignancy grading in brain tumor. This study was to evaluate the DWls with different b-values of various brain tumors in order to determine optimal b-values on 3T MR unit. Method: On a 3T MR unit, DWls with b-values of 1, 000, 3, 000 and 5, 000 s/mm2 were obtained in 20 patients of pathologically-proven brain tumors (7 metastases, 4 high grade gliomas, 2 Iymphomas, 2 low grade gliomas, 2 germinomas, and one each of germinoma, meningioma, hemangioblastoma and central neurocytoma. The overall image quality, contrast between normal brain parenchyma and tumor and signal intensities of solid and cystic components were comparatively evaluated among DWls with different b-values by visual inspection.

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