• Investigative Magnetic Resonance Imaging
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• v.20 no.4
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• pp.259-263
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• 2016

Primary diffuse large B-cell lymphoma of the seminal vesicle is an extremely rare disorder, with only two cases reported in the English literature. Here, we present imaging findings of a case of primary diffuse large B-cell lymphoma of the seminal vesicle. On transrectal ultrasonography, the mass presented as a 3.0-cm-sized heterogeneous, hypoechoic lesion in the right seminal vesicle. Computed tomography (CT) revealed a mass with rim-like enhancement in the right seminal vesicle. On magnetic resonance imaging (MRI), the tumor showed iso-signal intensity on T1-weighted images and heterogeneously intermediate-high signal intensity on T2-weighted images. The tumor showed rim-like and progressive enhancement with non-enhancing portion on dynamic scanning. Diffusion restriction was observed in the mass. On fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET/CT) imaging, a high standardized uptake value (maxSUV, 23.5) by the tumor was noted exclusively in the right seminal vesicle.

• Investigative Magnetic Resonance Imaging
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• v.22 no.2
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• pp.131-134
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• 2018

Susceptibility-weighted imaging (SWI) is well known for detecting the presence of hemorrhagic transformation, microbleeds and the susceptibility of vessel signs in acute ischemic stroke. But in some cases, it can provide the tissue perfusion state as well. We describe a case of a patient with hyperacute ischemic infarction that had a slightly hypodense, patchy lesion at the left thalamus on the initial SWI, with a left proximal posterior cerebral artery occlusion on a magnetic resonance (MR) angiography and delayed time-to-peak on an MR perfusion performed two hours after symptom onset. No obvious abnormal signals at any intensity were found on the initial diffusion-weighted imaging (DWI). On a follow-up MR image (MRI), an acute ischemic infarction was seen on DWI, which is the same location as the lesion on SWI. The hypointensity on the initial SWI reflects the susceptibility artifact caused by an increased deoxyhemoglobin in the affected tissue and vessels, which reflects the hypoperfusion state due to decreasing arterial flow. It precedes the signal change on DWI that reflects a cytotoxic edema. This case highlights that, in some hyperacute stages of ischemic stroke, hypointensity on an SWI may be a finding before the hyperintensity is seen on a DWI.

• Journal of Biomedical Engineering Research
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• v.15 no.4
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• pp.401-406
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• 1994

A magnetic resonance neurography technique for exclusive imaging of nerve networks is proposed. In the proposed technique, the anisotropy of diffusion coefficients of the molecules inside nerve cells was utilized to effectively suppress the magnetic resonance signal radiating from ones other than nerve tissues. Two images were obtained with diffusionweighting magnetic field gradients applied in the parallel and perpendicular directions with respect to the nerve orientation. One image was then subtract- ted from the other to form the neurogram. Experimentally obtained neurograms of the squld are presented.

• Korean Journal of Radiology
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• v.22 no.10
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• pp.1708-1718
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• 2021

Objective: The purpose of this study was to evaluate the magnetic resonance (MR) characteristics and applicability of new, uniform, extremely small iron-based nanoparticles (ESIONs) with 3-4-nm iron cores using contrast-enhanced magnetic resonance angiography (MRA). Materials and Methods: Seven types of ESIONs were used in phantom and animal experiments with 1.5T, 3T, and 4.7T scanners. The MR characteristics of the ESIONs were evaluated via phantom experiments. With the ESIONs selected by the phantom experiments, animal experiments were performed on eight rabbits. In the animal experiments, the in vivo kinetics and enhancement effect of the ESIONs were evaluated using half-diluted and non-diluted ESIONs. The between-group differences were assessed using a linear mixed model. A commercially available gadolinium-based contrast agent (GBCA) was used as a control. Results: All ESIONs showed a good T1 shortening effect and were applicable for MRA at 1.5T and 3T. The relaxivity ratio of the ESIONs increased with increasing magnetic field strength. In the animal experiments, the ESIONs showed peak signal intensity on the first-pass images and persistent vascular enhancement until 90 minutes. On the 1-week follow-up images, the ESIONs were nearly washed out from the vascular structures and organs. The peak signal intensity on the first-pass images showed no significant difference between the non-diluted ESIONs with 3-mm iron cores and GBCA (p = 1.000). On the 10-minutes post-contrast images, the non-diluted ESIONs showed a significantly higher signal intensity than did the GBCA (p < 0.001). Conclusion: In the phantom experiments, the ESIONs with 3-4-nm iron oxide cores showed a good T1 shortening effect at 1.5T and 3T. In the animal experiments, the ESIONs with 3-nm iron cores showed comparable enhancement on the first-pass images and superior enhancement effect on the delayed images compared to the commercially available GBCA at 3T.

• Journal of Korean Neurosurgical Society
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• v.56 no.6
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• pp.504-508
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• 2014

A 59-year-old male patient had 5-month history of gait disturbance and memory impairment. His initial brain computed tomography scan showed $3.5{\times}2.8cm$ sized mass with high density in the pineal region. The tumor was hypointense on T2 weighted magnetic resonance images and hyperintense on T1 weighted magnetic resonance images with heterogenous enhancement of central portion. The tumor was totally removed via the occipital transtentorial approach. Black mass was observed in the operation field, and after surgery, histopathological examination confirmed the diagnosis of malignant melanoma. Whole spine magnetic resonance images and whole body 18-fluoro-deoxyglucose positron emission tomography could not demonstrate the primary site of this melanoma. Scrupulous physical examination of his skin and mucosa was done and dark pigmented lesion on his left leg was found, but additional studies including magnetic resonance images and skin biopsy showed negative finding. As a result, final diagnosis of primary pineal malignant melanoma was made. He underwent treatment with the whole brain radiotherapy and extended local boost irradiation without chemotherapy. His preoperative symptoms were disappeared, and no other specific neurological deficits were founded. His follow-up image studies showed no recurrence or distant metastasis until 26 weeks after surgery. Primary pineal malignant melanomas are extremely rare intracranial tumors, and only 17 cases have been reported since 1899. The most recent case report showed favorable outcome by subtotal tumor resection followed by whole brain and extended local irradiation without chemotherapy. Our case is another result to prove that total tumor resection with radiotherapy can be the current optimal treatment for primary malignant melanoma in the pineal region.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.23 no.1
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• pp.7-14
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• 1993

The Internal derangement of temporomandibular joint disc was evaluated by using magnetic resonance imaging and arthrogram in 5 patients having reciprocal clicking or locking and in 5 normal subjects. Parasagittal multisections on both closed and open mouth were serially obtained by using a 1.5 Tesla MR system and surface coil with CSMEMP, MPGR. MR images obtained were analized by correlating with images of arthrograms. The obtained results were as follows: 1. Displaced meniscus was clearly delineated as dark structure on MR images other than on arthrograms of closed mouth view of patient having clicking or locking. 2. The deltoid white images of synovial fluid were identified in the glenoid fossa and on the posterior surface of condyle on open mouth view and partly depicted on closed mouth view, of parasagittal sections by MPGR. 3. The greyish image of joint fluid was identified on the posterior surface of condyle on the open mouth view of parasagittal sections by CSMEMP. 4. The structural relationship among condyle, meniscus, and fluid showed the variety of images on each parasagitta1 view.

• Imaging Science in Dentistry
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• v.31 no.4
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• pp.235-240
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• 2001

Purpose: To evaluate displacement and morphologic changes of the temporomandibular joint (TMJ) disc in patient with internal derangement using magnetic resonance imaging (MRI). Materials and Methods: One hundred and forty five MR images of TMJs in 73 patients were evaluated. Positional and morphologic changes of the TMJ discs were assessed. Lateral or medial disc displacement was also evaluated on coronal images. Results: Among 63 discs with anterior disc displacement, 37 discs were assessed as a biconcave disc and 21 as a deformed disc. Rotational disc displacement was observed in 35 discs. Anteromedial disc displacement was observed in 29 discs, and anterolateral direction in 6 discs. Among 35 rotational displacement, 5 biconcave discs and 21 deformed discs were observed. Conclusion : Rotational and sideways displacement of TMJ discs were found to be common and an important aspect of internal derangement. This study also suggests that sagittal and coronal images of the TMJ have complementary abilities for an assessment of joint abnormality.

• Investigative Magnetic Resonance Imaging
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• v.16 no.2
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• pp.184-188
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• 2012

Anoperineal tuberculosis is a rare extrapulmonary form of the disease and may present as abscess. We report a case of anoperineal tuberculous abscess, which showed low signal intensity on T1-weighted images, high signal intensity on T2-weighted images and diffusion restriction on diffusion weighted images.

• Investigative Magnetic Resonance Imaging
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• v.13 no.1
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• pp.93-96
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• 2009

Primary localized amyloidosis of the ureter and bladder is a very rare condition. CT and cystoscopic findings are indistinguishable from malignant neoplasm or inflammatory lesions. We report a case of unilateral distal ureteral thickening caused by primary localized amyloidosis. MR image features of hypointensity on T2-weighted images and mural enhancing pattern on contrast enhanced T1-weighted images can be helpful for diagnosis of ureteral amyloidosis.

• Investigative Magnetic Resonance Imaging
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• v.22 no.1
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• pp.71-77
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• 2018

Purpose: To develop a two-dimensional (2D) image-based respiratory motion correction technique for free-breathing coronary magnetic resonance angiography (MRA). Materials and Methods: The proposed respiratory navigator obtained aliased a 2D sagittal image from under-sampled k-space data and utilized motion correlation between the aliased images. The proposed navigator was incorporated into the conventional coronary MRA sequence including the diaphragm navigator and tested in three healthy subjects. Results: The delineation of major coronary arteries was significantly improved using the proposed 2D motion correction (S/I and A/P) compared to one-dimensional (S/I) correction using the conventional diaphragm navigator. Conclusion: The 2D image-based respiratory navigator was proposed for free-breathing coronary angiography and showed the potential for improving respiratory motion correction compared to the conventional 1D correction.