• Journal of radiological science and technology
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• v.32 no.1
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• pp.95-99
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• 2009

The purpose of this research is to seek SPAIR's reversal time (TI) which satisfies two conditions ; maintaining the suppression ability of fat tissue and simultaneously minimizing the inhomogeneity of fat tissue in T2 high-speed spin echo 3.0T magnetic resonance image (MRI) of the brain, and to compare SPAIR with STIR which is fat-suppression technique. The reversal times (TI) of SPAIR protocol are set to 1/2, 1/3, 1/6 and 1/12 of SPAIR TR (420 msec), namely 210 msec (8 people), 140 msec (26 people), 70 msec (26 people) and 35 msec (18 people) and STIR TI is set with 250 msec (26 people). With these parameter sets, we acquired the axis direction 104 images of the brain. In ROI ($50\;mm^2$) of output image, signal intensities of the fatty tissue, the muscular tissue, and the background were measured and the CNRs of fatty tissue and the muscular tissue were calculated. The inhomogeneity of the fatty tissue is SD/mean, where SD is the standard deviation and 'mean' is a average fatty tissue signal. Consequently, SPAIR TI is determined on either 1/3 or 1/6 of TR (420 ms) ; 140 ms or 70 ms. Because the difference of statistics in fat-suppression ability and inhomogeneity of fatty tissue is very small (p < 0.001), Selecting 140 ms seems to be better choice for the image quality. Meanwhile, Comparing SPAIR (TI : 140 ms) with STIR, the fat-suppression is not able to be considered statistically (p < 0.252), but the image quality is able to be considered statistically (p < 0.01). In conclusion, SPAIR is better than STIR in the image quality.

• Investigative Magnetic Resonance Imaging
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• v.4 no.2
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• pp.85-93
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• 2000

Purpose: To evaluate the availability of magnetic resonance (MRI voiding cystography for the diagnosis of vesicoureteral reflux (VUR) and to compare the sensitivity of MR voiding cystography (MRVC) with that of radiographic voiding cystourethrography (VCUG) in the detection of VUR. Material and Methods : MRVC was performed upon 20 children referred for investigation of VUR. Either coronal T1-weighted spin-echo or spoiled gradient-echo images were obtained before and after transurethral administration of a mixture of normal saline and gadopentetate dimeglumine, and immediately after voiding. The findings of MRVC were compared with those of VCUG performed within 6 months of MRVC. Results 1 VUR was detected in 23 ureterorenal units f16 VUR's by both methods, five VUR's by VCUG, and two VUR's by MRVC). The sensitivity of VCUG and MRVC in detecting VUR was 91.3% (21/23) and 78.3% (18/23), respectively. MRVC detected renal scarring in 15 out of 17 kidneys with scintigraphically detected renal scarring. Conclusion : Although MRVC is slightly less sensitive than VCUG in the detection of VUR, it can be used for the diagnosis of VUR and renal scarring simultaneouslyl and thus will reduce the radiation hazard.

• Investigative Magnetic Resonance Imaging
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• v.18 no.1
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• pp.7-16
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• 2014

Purpose : To evaluate the prevalence and pattern of perfusion defect (PD) on first-pass stress perfusion MR imaging in relation with the degree of left ventricular hypertrophy (LVH) and late gadolinium-enhancement (LGE) in patients with apical hypertrophic cardiomyopathy (APH). Materials and Methods: Cardiac MR imaging with first-pass stress perfusion, cine, and LGE sequence was performed in 26 patients with APH from January 2008 to December 2012. We analyzed a total of 416 segments for LV wall thickness on end-diastolic phase of cine images, and evaluated the number of hypertrophied segment and number of consecutive hypertrophied segment (NCH). We assessed the presence or absence of PD and LGE from all patients. If there was PD, we subdivided the pattern into sporadic (sporadic-PD) or ring (ring-PD). Using univariate logistic method, we obtained the independent predictor for presence of overall PD and ring-PD. Results: PD on stress perfusion MRI was observed in 20 patients (76.9%), 12 of them (60%) showed ring-PD. Maximal LV wall thickness and number of hypertrophied segment were independent predictors for overall PD (all, p < 0.05). NCH with more than 3 segments was an additional independent factor for ring-PD. However, LGE was not statistically related with PD in patients with APH. Conclusion: About three quarters of the patients with APH showed PD, most of them represented as ring-PD. LVH degree or distribution was related with pattern of PD, however, LGE was not related with PD. Therefore, the clinical significance of PD in the patients with APH seems to be different from those with non-APH, and further comparison study between the two groups should be carried out.

• Investigative Magnetic Resonance Imaging
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• v.18 no.1
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• pp.17-24
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• 2014

Purpose : To determine whether high-resolution contrast-enhanced three dimensional imaging with spoiled gradient-recalled sequence (HR-CE 3D-SPGR) plays a meaningful role in the assessment of intracranial vertebral artery (ICVA) and posterior inferior cerebellar artery (PICA) in lateral medullary infarction (LMI). Materials and Methods: Twenty-five patients confirmed with LMI were retrospectively enrolled with approval by the IRB of our institute, and 3T MRI with HR-CE 3D-SPGR and contrast-enhanced magnetic resonance angiography (CE-MRA) were performed. Two radiologists who were blinded to clinical information and other brain MR images including diffusion weighted image independently evaluated arterial lesions in ICVA and PICA. The demographic characteristics, the area of LMI and cerebellar involvement were analyzed and compared between patients with arterial lesion in ICVA only and patients with arterial lesions in both ICVA and PICA on HR-CE 3D-SPGR. Results: Twenty-two of twenty-five LMI patients had arterial lesions in ICVA or PICA on HR-CE 3D SPGR. However twelve arterial lesions in PICA were not shown on CE-MRA. Concurrent cerebellar involvement appeared more in LMI patients with arterial lesion in ICVA and PICA than those with arterial lesion in ICVA alone (p = 0.069). Conclusion: HR-CE 3D-SPGR can help evaluate arterial lesions in ICVA and PICA for LMI patients.

• Investigative Magnetic Resonance Imaging
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• v.17 no.4
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• pp.267-274
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• 2013

Purpose : To re-evaluate additional clinical significance of the apparent diffusion coefficient (ADC) map in the inference of infarction stage, authors studied the evolution patterns of the DWI and the ADC map of the brain infarction. Materials and Methods: In 127 patients with cerebral infarctions, including follow-up checks, 199 studies were performed. They were classified as hourly (117 studies)-, daily (108 studies)-, weekly (62 studies)-based groups. The signal intensity (SI) was measured at the core of the infarction and contralateral area with ROI of 0.3 $cm^2$ or more on the images of the DWI and the ADC map, and calculated the ratios of SI and ADC value of the infarction area / contralateral normal area, and compared the patterns of the change according to the evolution. Results: Infarction was detected as early as 1 hour after the attack, and the ratio of SI in the DWI became over than 2 after 12 hours, which showed a plateau until the 6th day. Thereafter, it decreased slowly to 1 on the 30th day, and changed to lower SI than the surrounding brain. The ratio in the ADC map became 0.46 in 24 hours after the attack, and increased slowly to 1 in the 15th day. Thereafter, it became a higher value than the surrounding brain. Overall, the ratio in the ADC map changed earlier than in the DWI, and the ratio curves showed inverse pattern each other according to the evolution of the infarction. Conclusion: The evolution patterns of infarction on the ADC map showed an inverse curve of DWI curve, which means that the ADC value is accurately predictable from DWI, and the ADC map joined with the DWI seems helpful in the determination of subacute infarction between 15 to 30 days.

• The Korean Journal of Nuclear Medicine
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• v.31 no.1
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• pp.90-101
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• 1997

The purpose of this study is to evaluate the diagnostic accuracy of various quantitative indices for the differentiation of benign from malignant primary soft tissue tumors by FDG-PET. A series of 32 patients with a variety of histologically or clinically confirmed benign (20) or malignant (12) soft tissue lesions were evaluated with emission whole body (5min/bed position) PET after injection of [$^{18}F$]FDG. Regional 20min transmission scan for the attenuation correction and calculation of SUV was performed in 16 patients (10 benign, 6malignant) followed by dynamic acquisition for 56min. Postinjection transmission scan for the attenuation correction and calculation of SUV was executed in the other 16 patients (10 benign, 6 malignant). The following indices were obtained. the peak and average SUV (pSUV, aSUV) of lesions, tumor-to-background ratio acquired at images of 51 min p.i. ($TBR_{51}$), tumor-to-background ratio of areas under time-activity curves ($TBR_{area}$) and the ratio between the activities of tumor ROI at 51 min p. i. and at the time which background ROI reaches maximum activity on the time-activity curves ($T_{51}/T_{max}$). The pSUV, aSUV, $TBR_{51}$, and $TBR_{area}$ in malignant lesions were significantly higher than those in benign lesions. We set the cut-off values of pSUV, aSUV, $TBR_{51},\;TBR_{area}$ and $T_{51}/T_{max}$ for the differentiation of benign and malignant lesions at 3.5, 2.8, 5.1, 4.3 and 1.55, respectively. The sensitivity, specificity and accuracy were 91.7%, 80.0%, 84.4% by pSUV and aSUV, 83.3%, 85.0%, 84.4% by $TBR_{51}$, 83.3%, 100%, 93.8% by $TBR_{area}$ and 66.7%, 70.0%, 68.8% by $T_{51}/T_{max}$. The time-activity curves did not give additional information compared to SUV or TBR. The one false negative was a case with low-grade fibrosarcoma and all four false positives were cases with inflammatory change on histology. The visual, analysis of FDG-PET also detected the metastatic lesions in malignant cases with comparable accuracy In conclusion, all pSUV, aSUV, $TBR_{51}$, and $TBR_{area}$ are useful metabolic semi-quantitative indices with good accuracy for the differentiation of benign from malignant soft-tissue lesions.

• The Korean Journal of Nuclear Medicine
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• v.38 no.4
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• pp.288-293
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• 2004

Purpose: increased uptake of wrist and hand joints in three phase bone scintigraphy (TPBS) have been used in the detection of reflex sympathetic dystrophy syndrome (RSDS). TPBS frequently shows increased shoulder uptake in the hemiplegic RSDS patients. We investigated the significance of the shoulder uptake in the detection of these patients. Materials and Methods: Twenty three patients who had hemiplegia due to brain stroke and diagnosed as RSD were enrolled in this study (M:F=16:7, R:L=11:12). The mean age was $63{\pm}10$ yrs. Ter normal volunteer (mean age: $60{\pm}5$, M:F=1:9) data was used as control group. TPBS was performed $59{\pm}32$ days after stoke (acute stage). We obtained the count ratios of bilateral hands by drawing a region of interest (ROI) in three phase images and compared to the count ratios of shoulders in the delayed image. Hand ROI included an ipsilateral wrist. Sensitivity of detecting the affected limb was defined using the right/left count ratio of normal control. Results: Sensitivities using count ratios of hand blood flow, blood pool and delayed image were 45%, 76% and 78%, respectively. Sensitivity of shoulder count ratio was 74%. Log of right/left counts of hand delayed image and that of shoulder delayed image were correlated well with statistical significance (Spearman's R=0.824, p<0.001). Conclusion: Shoulder uptake showed good correlation with hand uptake in the delayed image of TPBS. Shoulder uptake maybe helpful in the diagnosis of reflex sympathetic dystrophy syndrome in patients with hemiplegia.

• Journal of radiological science and technology
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• v.34 no.4
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• pp.323-331
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• 2011

We evaluated clinical usefulness of Arterial spin labeling perfusion MR imaging on the acute ischemic cerebral infarction patients through this study. We compared 22 patients who were done with DSC imaging and ASL imaging in admitted emergency room with acute ischemic cerebral infarction, with 36 normal comparison persons (DSC image on 21persons, ASL images on 15persons). Siemens Magnetom Verio 3.0T with 12 channel head coil was used for this study. DSC image obtained 4 maps(rCBV, rCBF, rMTT, TTP) through post-processing. For qualitative analysis we compared the area of lesion macro-diagonal with the size of diffusion weighted MR image for rMTT, TTP, rCBF, rCBV, ASL maps. For Quantitative analysis we analyzed significant correlations between less than 3 cm infarction group and normal comparison group using mean relative value of flowing image with Mann-Whitney U test. TTP(95.5%) and rCBF(95.5%) maps showed high recognition rate in qualitative analysis for >3cm infarction group. The rCBF and rCBV map tests were highly related with final stage stroke areas. Mean relative value of infarction group showed a significant correlations in quantitative analysis(p<0.05). As a conclusion, arterial spin labeling image showed high lesion recognition rate in the >3cm infarction group. Mean relative values in quantitative evaluation were used for reference data. If we do more sustainable researches, ASL image will be useful for an early diagnosis of cerebral infarction, determination of the range of ischemic pneumbra and effective treatments.

• Radiation Oncology Journal
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• v.21 no.2
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• pp.107-111
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• 2003

Purpose: To establish the role of stereoactic radiosurgery using a linear accelerator for the treatment of patients with cavernous angloma. Materials and Methods: Between February 1995 and May 1997, 11 patients with cavernous angioma were treated with stereotactic radiosurgery using a linear accelerator. Diagnoses were based on the magnetic resonance imaging in 8 patients, and the histological in 3. The vascular lesions were located on the brainstem (5 cases), cerebellum (2 cases) thalamus (1 case) and cerebrum (3 cases). The clinical presentation at onset included previous intracerebral hemorrhages (9 cases) and seizures (2 cases). All patients were treated with a a linac-based radiosurgery. The median dose of radiation delivered was 16 Gy ranging from 14 to 24 Gy, which was typically proscribed to the 80$\%$ isodose surface (range 50 $\~$ 80$\%$), corresponding to the periphery of the lesion with a single isocenter. Ten patients were followed-up. Results: The median follow-up was 49 months ranging from 8 to 73 months, during which time two patients developed an intracerebral hemorrhage, 1 at 8 months, with the other at 64 months post radiosurgery. One patient developed neurological deficit after radiosurgery, and two developed an edema on the T2 weighted images of the MRI surrounding the radiosurgical target. Conclusion: The use of stereotactic radiosurgery in the treatment of a cavernous angioma may be effective in the prevention of rebleedlng, and can be safely delivered. However, a longer follow-up period will be required.

• Investigative Magnetic Resonance Imaging
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• v.17 no.3
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• pp.181-191
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• 2013

Purpose : To evaluate the usefulness of in vivo magnetic resonance (MR) imaging for tracking intravenously injected superparamagnetic iron oxide (SPIO)-labeled human umbilical vein endothelial cells (HUVECs) in an acute renal failure (ARF) rat model. Materials and Methods: HUVECs were labeled with SPIO and poly-L-lysine (PLL) complex. Relaxation rates at 1.5-T MR, cell viability, and labeling stability were assessed. HUVECs were injected into the tail vein of ARF rats (labeled cells in 10 rats, unlabeled cells in 2 rats). Follow-up serial $T2^*$-weighted gradient-echo MR imaging was performed at 1, 3, 5 and 7 days after injection, and the MR findings were compared with histologic findings. Results: There was an average of $98.4{\pm}2.4%$ Prussian blue stain-positive cells after labeling with SPIOPLL complex. Relaxation rates ($R2^*$) of all cultured HUVECs at day 3 and 5 were not markedly decreased compared with that at day 1. The stability of SPIO in HUVECs was maintained during the proliferation of HUVECs in culture media. In the presence of left unilateral renal artery ischemia, $T2^*$-weighted MR imaging performed 1 day after the intravenous injection of labeled HUVECs revealed a significant signal intensity (SI) loss exclusively in the left renal outer medulla regions, but not in the right kidney. The MR imaging findings at days 3, 5 and 7 after intravenous injection of HUVECs showed a SI loss in the outer medulla regions of the ischemically injured kidney, but the SI progressively recovered with time and the right kidney did not have a significant change in SI in the same period. Upon histologic analysis, the SI loss on MR images was correspondent to the presence of Prussian blue stained cells, primarily in the renal outer medulla. Conclusion: MR imaging appears to be useful for in vivo monitoring of intravenously injected SPIO-labeled HUVECs in an ischemically injured rat kidney.