• Korean Journal of Veterinary Research
• /
• v.44 no.2
• /
• pp.311-315
• /
• 2004

The detection of lymph node metastasis is an important step in tumor staging and is significant for therapy planning. It has been challenged to yield an appropriate image with diagnostic methods such as Magnetic Resonance (MR) and Computed Tomography (CT). Though CT has been used widely and accessed easily to show internal organs, it can hardly provide difference between lymph node and adjacent vessel or fat tissue. It has been well established that MR can reveal the subtle discrepancy within soft tissue. This study investigated the suitability of MR lymph node imaging without contrast enhancement by comparison of T1-weighted image (T1WI) and T2- weighted image (T2WI) in ten normal rabbits. According to the pulse sequence optimized from preliminary study, T1-weighted spin-echo (repetition time/echo time=400/12 ms) and T-2 weighted fast spin-echo (repetition time/echo time=3500/84 ms) images covering the hind limbs and pelvic region were acquired at 1.5 T. Two radiologists scrupulously evaluated the MR images in consensus. And signal intensity of lymph nodes was compared with that of adjacent fat. Statistical analysis showed that T1-weighted coronal image visualized the lymph nodes (iliac, superficial inguinal and popliteal lymph nodes) quickly and consistently rather than T2-weighted one. Conclusively, T1WI for evaluation of lymph nodes is moderately better than T2WI and appears to have potential for quick and sufficient mapping of the lymph nodes. In addition, this normal MR image of lymph nodes could be applied to further study for the evaluation of lymphatic system in abscess and tumor bearing animal model.

• Investigative Magnetic Resonance Imaging
• /
• v.2 no.1
• /
• pp.14-30
• /
• 1998

Manganese is an essential element in the body. It is mainly deposited in the liver and to a lesser degree in the basal ganglia of the brain and eliminated through the bile duct. Rapid turnover of managanese in the body makes it difficult to evaluate the manganese exposure in workers, esecially in those with irregular or intermittent exposure, like welders. Therefore, conventional biomarkers, including blood and urine manganese can provide only a limited information about the long-tern or cumulative exposure to manganese. Introduction of magnetic resonance imaging (MRI) made a progress in the assessment of manganese exposure in the medical conditions related to manganese accumulation, e. g. hepatic failure and long-term total parenteral nutrition. Manganese shortens spin-lattice(T1) relaxation time on MRI due to its paramagnetic property, resulting in high signal intensity (HSI) on T1-weighted image(T1W1) of MRI. Manganese deposition in the brain, therefore, can be visualizedas an HSI in the globus pallidus, the substantia nigra, the putamen and the pituitary. clinical and epidemiologic studies regarding the MRI findings in the cases of occupational and non-occupational manganese exposure were reviewed. relationships between HSI on T1W1 of MRI and age, gender, occupational manganese exposure, and neurological dysfunction were analysed. Relationships betwen biological exposure indices and HSI on MRE werealso reviewed. Literatures were reviewed to establish the relationships between HSI, Manganese deposition in the brain, pathologic findings, and neurological dysfunction. HSI on T1W1 of MRI reflects regional manganese deposition in the brain. This relationship enables an estimation of regional manganese deposition in the brain by analysing MR signal intensity. Manganese deposition in the brain can induce a neuronal loss in the basal ganglia but functional abnormality is supposed to be related to the cumulative exposure of manganese in the brain, use of brain MRI for the assessment of exposure in a group of workers seems to be hardly rationalized, while ti can be a useful adjunct for the evaluation of manganese exposure int he cases with suspected manganese-related health problems.

• Journal of the Korean Society of Radiology
• /
• v.17 no.3
• /
• pp.375-384
• /
• 2023

Most Hepatic hemangiomas are asymptomatic and small in size, making them difficult to find by pathological examination. Therefore, radiological diagnosis is essential for the early finding and diagnosis of Hepatic hemangioma. Three-phase method using contrast medium in computed tomography, T1, T2-weighted imaging in magnetic resonance imaging, dynamic magnetic resonance imaging using contrast medium, echo planar imaging method, diffusion-weighted imaging method, blood pool scan using ^99mTc-labeled red blood cells in nuclear medicine, we looked at the color doppler method In ultrasound, and it is important to accurately understand the imaging findings of hepatic hemangioma and perform the examination in order to make an accurate diagnosis. most hepatic hemangioma are benign tumors, care should be taken not to confuse them with malignant tumors such as hepatocellular carcinoma to prevent unnecessary procedures. Therefore, in order to make an accurate diagnosis, it is important to accurately understand the imaging findings of hemangioma and perform the examination.

• Investigative Magnetic Resonance Imaging
• /
• v.8 no.2
• /
• pp.100-108
• /
• 2004

Purpose : Early degeneration of articular cartilage is accompanied by a loss of glycosaminoglycan (GAG) and the consequent change of the integrity. The purpose of this study was to biochemically quantify the loss of GAG, and to evaluate the $Gd(DTPA)^{2-}$-enhanced, and T1, T2, rho relaxation map for detection of the early degeneration of cartilage. Materials and Methods : A cartilage-bone block in size of $8mm\;\times\;10mm$ was acquired from the patella in each of three pigs. Quantitative analysis of GAG of cartilage was performed at spectrophotometry by use of dimethylmethylene blue. Each of cartilage blocks was cultured in one of three different media: two different culture media (0.2 mg/ml trypsin solution, 1mM Gd $(DTPA)^{2-}$ mixed trypsin solution) and the control media (phosphate buffered saline (PBS)). The cartilage blocks were cultured for 5 hrs, during which MR images of the blocks were obtained at one hour interval (0 hr, 1 hr, 2 hr, 3 hr, 4 hr, 5 hr). And then, additional culture was done for 24 hrs and 48 hrs. Both T1-weighted image (TR/TE, 450/22 ms), and mixed-echo sequence (TR/TE, 760/21-168ms; 8 echoes) were obtained at all times using field of view 50 mm, slice thickness 2 mm, and matrix $256\times512$. The MRI data were analyzed with pixel-by-pixel comparisons. The cultured cartilage-bone blocks were microscopically observed using hematoxylin & eosin, toluidine blue, alcian blue, and trichrome stains. Results : At quantitation analysis, GAG concentration in the culture solutions was proportional to the culture durations. The T1-signal of the cartilage-bone block cultured in the $Gd(DTPA)^{2-}$ mixed solution was significantly higher ($42\%$ in average, p<0.05) than that of the cartilage-bone block cultured in the trypsin solution alone. The T1, T2, rho relaxation times of cultured tissue were not significantly correlated with culture duration (p>0.05). However the focal increase in T1 relaxation time at superficial and transitional layers of cartilage was seen in $Gd(DTPA)^{2-}$ mixed culture. Toluidine blue and alcian blue stains revealed multiple defects in whole thickness of the cartilage cultured in trypsin media. Conclusion : The quantitative analysis showed gradual loss of GAG proportional to the culture duration. Microimagings of cartilage with $Gd(DTPA)^{2-}$-enhancement, relaxation maps were available by pixel size of $97.9\times195\;{\mu}m$. Loss of GAG over time better demonstrated with $Gd(DTPA)^{2-}$-enhanced images than with T1, T2, rho relaxation maps. Therefore $Gd(DTPA)^{2-}$-enhanced T1-weighted image is superior for detection of early degeneration of cartilage.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.7
• /
• pp.4380-4386
• /
• 2014

This study was conducted to minimize the imaging distortion by reducing the differences in susceptibility between the tissue and air surrounding it while performing a thyroid diffusion imaging procedure. The study group was composed of 23 healthy adults. Thyroids with many distortions near the air, larynx, and trachea were chosen to test and evaluate the diffusion imaging difference between before and after an application of silicon. As a result, there was reduced distortion with silicon application, and the differences decreased from 30% to 10%. According to One-way ANOVA and Duncan's post-hoc test, there were no significant differences between imaging with a silicon application and T2 imaging of the surface area, which was the standard image. In conclusion, this study presented a radical improvement in reducing the distortions in imaging by compensating for an uneven tissue surface near air without affecting the magnetic resonance contrast and complicating the imaging processes.

• Investigative Magnetic Resonance Imaging
• /
• v.16 no.2
• /
• pp.173-176
• /
• 2012

We report the radiological findings of regional enhancement of the liver adjacent to the right adrenal pheochromocytoma. CT and MRI showed focal strong enhancement of adjacent liver tissue in the arterial phase. However during the delayed phase, the lesion showed iso-attenuation with normal hepatic parenchyma and not delineated. The lesion did not show abnormal signal intensity on neither T1 nor T2 weighted images and indistinguishable from normal parenchyma. The enhancing hepatic lesion was spontaneously regressed on postoperative follow up CT which was taken several months after the adrenalectomy.

• The Journal of the Korean bone and joint tumor society
• /
• v.9 no.2
• /
• pp.148-154
• /
• 2003

Purpose: To correlate the significant MRI findings and histologic features of the Schwannoma of the extremities and to review the clinical characteristic and the result of the surgical enucleation. Materials and Methods: 67 patients with pathologically proven Schwannoma of the extremities, who were surgically treated at our institutes between January 1996 and June 2002, were selected for this study. The clinical records, EMG, MRI and histologic findings were reviewed. Age of the patients ranged from 8 to 75 years with average of 44.7 years. Mean follow-up period was 9.7 months with raging from 3 months to 46 months. Results: On MRI, Schwannoma shows a well-demarcated fusiform mass with a low to intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images, which is connected to parent nerve. A target pattern with peripheral hyperintensive rim and central low intensity on T2-weighted images was seen in 6 cases (15%), and fasciculation pattern with inhomogenous intensity in the hyperintensity on T2-weighted images was observed in 24 cases (62%). Various degree of cystic degeneration was discovered in 25 cases (64%). Postoperative complications include tingling sense or radiating pain in 5 patients, paresthesia in 2 patients, nerve palsy in 2 patients, but all of the complications were recovered during followup period. There were no local recurrence or malignant change. Conclusion: MRI demonstrates characteristic findings of Schwannoma, and very useful tool for preoperative diagnosis and planning of surgery. Exact preoperative diagnosis and meticulous enucleation are enough option of treatment.

• Investigative Magnetic Resonance Imaging
• /
• v.18 no.4
• /
• pp.290-302
• /
• 2014

Purpose : Susceptibility-weighted magnetic resonance (MR) sequence is three-dimensional (3D), spoiled gradient-echo pulse sequences that provide a high sensitivity for the detection of blood degradation products, calcifications, and iron deposits. This pictorial review is aimed at illustrating and discussing its main clinical applications. Materials and Methods: SWI is based on high-resolution, 3D, fully velocity-compensated gradient-echo sequences using both magnitude and phase images. To enhance the visibility of the venous structures, the magnitude images are multiplied with a phase mask generated from the filtered phase data, which are displayed at best after post-processing of the 3D dataset with the minimal intensity projection algorithm. A total of 200 patients underwent MR examinations that included SWI on a 3 tesla MR imager were enrolled. Results: SWI is very useful in detecting multiple brain disorders. Among the 200 patients, 80 showed developmental venous anomaly, 22 showed cavernous malformation, 12 showed calcifications in various conditions, 21 showed cerebrovascular accident with susceptibility vessel sign or microbleeds, 52 showed brain tumors, 2 showed diffuse axonal injury, 3 showed arteriovenous malformation, 5 showed dural arteriovenous fistula, 1 showed moyamoya disease, and 2 showed Parkinson's disease. Conclusion: SWI is useful in detecting occult low flow vascular lesions, calcification and microbleed and characterising diverse brain disorders.

• Progress in Medical Physics
• /
• v.12 no.2
• /
• pp.113-124
• /
• 2001

For veterinary imaging diagnosis, we obtained MR images of the canine brain, spine, kidney and pelvis from 3T MRI system which was equipped with the world first 3T active shield magnet. Spin echo (SE) and fast Spin Echo (FSE) images were obtained from the canine brain, spine, kidney and pelvis of normal and sick dogs using a homemade birdcage and transverse electromagnetic (TEM) resonators operating in quadrature and tuned to 128 MHz. In addition, we employed a homemade saddle shaped RF coil. Typical common acquisition parameters were as follows: matrix=512$\times$512, field of view (FOV)=20cm, slice thickness=3 w, number of excitations (NEX)=1. For T1-weighted MR images, we used TR=500 ms, TE=10 or 17.4 ms. For T2-weighted MR images, we used TR=4000 ms, TE=108 ms. Signal to noise ratio (SNR) of 3T system was measured 2.7 times greater than that of prevalent 1.57 system. The high resolution images acquired in this study represent more than a 4-fold increase in in-plane resolution relative to conventional images obtained with a 20 cm field of view and a 5 mm slice thickness. MR images obtained from 3T system revealed numerous small venous structures throughout the image plane and provided reasonable delineation between gray and white matter The present results demonstrate that the MR images from 3T system could provide better diagnostic quality of resolution and sensitivity than those of 1.5T system. The elevated SNR observed in the 3T high field magnetic resonance imaging can be utilized to acquire images with a level of resolution approaching the microscopic structural level under in vivo conditions. These images represent a significant advance in our ability to examine small anatomical features with noninvasive imaging methods. Moreover, MRI technique could begin to apply for veterinary medicine in Korea.

• Investigative Magnetic Resonance Imaging
• /
• v.3 no.1
• /
• pp.60-65
• /
• 1999

Purpose : The purpose of this study was to evaluate the image quality, contrast characteristics, and possible clinical utility of Medium Tau Inversion Recovery(MTIR) sequence with white matter suppression in patients with brain cortical lesion. Materials and methods : Two normal volunteers and twenty-one patients with cortical lesion were scanned with MTIR as well as other MR imaging sequences. Gray-white matter contrast was evaluated objectively using region-of-interest calculations, including percent contrast and contrast-to-noise ratio(CNR). MTIR sequence was visually compared with other sequences in 21 patients with cortical lesion including conspicuity and detection rate. Results : MTIR sequence had the highest present contrast and CNR between the gray matter and white matter. In twenty-one cases of cortical lesion including cortical dysplasia, MTIR sequence improved delineation and conspicuity of lesion, but MTIR sequence could not detect new lesions. Conclusion : The MTIR sequence well delineated the cortical lesions, particularly in including cortical dysplasia. It may be used as an adjunctive imaging sequence in case of poor gray and white matter differentiation with conventional T1-weighted sequences.