• Investigative Magnetic Resonance Imaging
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• v.13 no.1
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• pp.9-14
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• 2009

T1-, and T2-weighted imagings and FLAIR (fluid attenuated inversion recovery) imaging are fundamental imaging methods in the brain. T1-weighted imaging is a spin-echo sequence with short TR and short TE and produces the tissue contrast by different T1 relaxation times. In other words, short TR maximizes the difference of the longituidinal magnetization recovery between the tissues. T2-weighted imaging is a spin-echo sequence with long TR and long TE and produces the tissue contrast by different T2 relaxation times. Long TE maximizes the difference of the transverse magnetization decay between the tissues. FLAIR is an inversion recovery sequence using 180 degree inversion pulse. 2500 msec of inversion time is applied to suppress the CSF signal.

• Investigative Magnetic Resonance Imaging
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• v.25 no.3
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• pp.197-200
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• 2021

Ramsay Hunt syndrome (RHS) is a disease caused by varicella-zoster virus (VZV) infection that can be diagnosed through clinical symptoms with or without imaging evaluations. The typical features of RHS on imaging evaluation include signal changes and enhancement in the internal auditory canal (IAC) nerves, and the labyrinthine segment of cranial nerve VII (CN VII) and cranial nerve VIII (CN VIII). In some patients, inner ear structure (cochlear and vestibular apparatus) is involved in RHS. Neurologic complications, such as encephalitis and meningitis, are rare in RHS, but are known to occur. Therefore, magnetic resonance imaging (MRI) is necessary to detect both abnormal signal intensity in the IAC, CN VII, CN VIII, inner and ear structure, and CNS complications. We report an RHS patient with CN VII, VIII, and leptomeningeal enhancement within the cerebellar folia on 10-min delayed, contrast-enhanced (CE), three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) imaging.

• Proceedings of the KSMRM Conference
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• 1996.10a
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• pp.59-59
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• 1996

• Journal of the Korean Society of Radiology
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• v.81 no.5
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• pp.1239-1245
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• 2020

Reversible cerebral vasoconstriction syndrome (RCVS) is a clinical and radiological syndrome with primary features that include hyperacute onset of severe headache and segmental vasoconstriction of the cerebral arteries, which resolve within 3 months. Vessel wall enhancement has been reported in some cases of RCVS; however, its pathophysiological and diagnostic implications remain unclear. We review a case of RCVS in a patient with transient vessel wall enhancement on contrast-enhanced fluid-attenuated inversion recovery images, focusing on the pathophysiological and diagnostic implications.

• Journal of the Korean Society of Radiology
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• v.13 no.1
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• pp.55-63
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• 2019

It was reported that there were some cases in which signal was not inhibited but high signal appeared in cerebrospinal fluid on FLAIR(fluid attenuated inversion recovery) of MRI(Magnetic Resonance Imaging) in case a person inhales high-concentration oxygen. This study was to prepare basic database. We produced a phantom fixed with agar gel and by using it, obtained the images of the signals of normal saline into which oxygen was injected and normal saline diluted with contrast media by changing the TI(Inversion Time) of FLAIR technique and analyzed them. In the result of FLAIR technique of MRI using Philips Achieva MR 3.0T in Busan P Hospital, the SNR(Signal to Noise Ratio) of normal saline into which oxygen was injected was higher than the SNR of normal saline into which oxygen was not injected. However, it was not higher than the SNR of normal saline diluted with contrast media. In the TI 1,800ms, we could obtain the images which do not have the rise of the signal due to oxygen. In the CNR(Contrast to Noise Ratio) of normal saline into which oxygen was injected and normal saline diluted with contrast media as well, it was higher in the TI 1,800ms than in the TI 2,800ms that is mainly used clinically. It is thought that the result of this study could be basic database for studies on change of signal of cerebrospinal fluid as a result of injection of oxygen in FLAIR technique of MRI.

• 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.

• Investigative Magnetic Resonance Imaging
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• v.26 no.1
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• pp.32-42
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• 2022

Purpose: To evaluate the clinical benefit of 2D contrast-enhanced T2 fluid-attenuated inversion recovery (CE-T2 FLAIR) image for detecting leptomeningeal metastasis (LM) in the brain metastasis work-up for lung cancer. Materials and Methods: From June 2017 to July 2019, we collected all consecutive patients with lung cancer who underwent brain magnetic resonance image (MRI), including contrast-enhanced 3D fast spin echo T1 black-blood image (CE-T1WI) and CE-T2 FLAIR; we recruited clinico-radiologically suspected LM cases. Two independent readers analyzed the images for LM in three sessions: CE-T1WI, CE-T2 FLAIR, and their combination. Results: We recruited 526 patients with suspected lung cancer who underwent brain MRI; of these, we excluded 77 (insufficient image protocol, unclear pathology, different contrast media, poor image quality). Of the 449 patients, 34 were clinico-radiologically suspected to have LM; among them, 23 were diagnosed with true LM. The calculated detection performance of CE-T1WI, CE-T2 FLAIR, and combined analysis obtained from the 34 suspected LM were highest in the combined analysis (AUC: 0.80, 0.82, and 0.89, respectively). The inter-observer agreement was also the highest in the combined analysis (0.68, 0.72, and 0.86, respectively). In quantitative analyses, CNR of CE-T2 FLAIR was significantly higher than that of CE-T1WI (Wilcoxon signed rank test, P < 0.05). Conclusion: Adding CE-T2 FLAIR might provide better detection for LM in the brain-metastasis screening for lung cancer.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.297-299
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• 2022

Malignant glioma has a poor prognosis with the reported median survival of between 6 months to 14 months. Thus, it is crucial to predict the accurate survival of patients with malignant glioma. In this paper, we propose a convolutional neural network to predict the overall survival and age of the patients. A total of four MRI modalities, T1, T1-contrast enhanced, T2, and fluid-attenuated inversion recovery, which effectively capture spatial characteristics of malignant glioma, were used as input images. Age is an important factor impacting the overall survival, thus incorporating it into the model will thereby improve the performance of the proposed model. Our model successfully predicted overall survival and age of the patients with pearson correlation coefficients of 0.1748 and 0.3056, respectively.

• Journal of the Korean Society of Radiology
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• v.83 no.4
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• pp.945-950
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• 2022

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a common autoimmune encephalitis that is noted to be a severe but treatable disease entity. Patients with anti-NMDAR encephalitis often develop psychotic symptoms, including delusions, hallucinations, and paranoia, as well as memory impairment and persistent loss of attention. However, MRI findings in such patients show no abnormalities in most cases. Although typical brain abnormality features, known as T2 hyperintensities, involve the brain parenchyma and contrast enhancement at the cerebral cortex or overlying meninges, isolated leptomeningeal enhancement has been rarely reported in anti-NMDAR encephalitis. Herein, we report a patient with anti-NMDAR encephalitis who presented with isolated leptomeningeal enhancement, additionally showing the diagnostic value of contrast-enhanced fluid-attenuated inversion recovery imaging.

• 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.