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Purpose: The presence of a flow-related signal in the normal dural sinus time of flight magnetic resonance angiography (TOF MRA) is common. This study aimed to identify changes in signal intensity in the dural sinus caused by changes in patient position. Materials and Methods: The researchers performed an elevation TOF MRA of the cerebral region in 52 patients, who showed abnormal flow-related signals in the dural sinuses on supine position. Flow-related signal intensity in the dural sinuses was then analyzed. Results: Flow-related signals were seen in 114 sites (52 patients), specifically in the internal jugular vein (IJV), sigmoid sinus (SS), inferior petrosal sinus (IPS), and cavernous sinus (CS) in 29 sites, 33 sites, 32 sites, and 20 sites, respectively. After head elevation, flow-related signal changes were then observed in the IJV, SS, IPS, and CS in 107 sites (107/114, 93.9%). There was loss of signal (62/114, 54.4%), or decrease (39/114, 34.2%), increase (6/114, 5.3%), or no change (7/114, 6.1%) in the signal intensity, and flow related signals were more frequent on the left than on the right. Conclusion: Flow-related signals in the dural sinuses on TOF MRA were decreased or disappeared by head elevation in 88.6% of the sites. Head elevation may help distinguish between pathologic and physiologic states.

Purpose Intra-arterial revascularization therapy (IART) for acute ischemic stroke has become increasingly popular recently. However, early change in apparent diffusion coefficient (ADC) values after full recanalization in human stroke has not received much attention. The aim of this study was to evaluate ADC changes immediately after interventional full-recanalization in patients with acute ischemic stroke. Materials and Methods ADC values of 25 lesions from 18 acute ischemic stroke patients were recorded with both pre- and post-recanalization ADC maps. Measurement was done by placing region of interests over the representative images of the lesion. For analysis, lesions were divided into territorial infarction (TI) and watershed infarction (WI). Results Mean ADC values of the overall 25 lesions before IART were 415.12 × 10-6 mm2/sec, and increased to 619.08 × 10-6 mm2/sec after the IART. Average relative ADC (rADC) value for 22 TI increased from 0.59 to 0.92 (p < 0.000), whereas, average rADC value for 3 WI did not change significantly. Conclusion There was a conspicuous increase of ADC values immediately after full-recanalization in TI lesions. On the other hand, WI lesions did not show significant change in ADC values after recanalization.

Purpose: To evaluate the utility of signal intensity differences between in- and opposed-phase MRI and the lipid peak ratio in in-vivo proton MR spectroscopy of the gallbladder as diagnostic tools for measuring the lipidcontent of gallbladder bile. Materials and Methods: Twenty-six normal volunteers underwent MR imaging (FMPSPGR) and in-vivo proton MR spectroscopy of the gallbladder. In all cases the results of liver function tests were normal, as were cholesterol levels,and ultrasonography of the gaubladder revealed nothing unusual. For MRI and MRS a 1.5T unit (Signa Horizon; GE Medical Systems, Milwaukee, U.S.A.) was used. In-phase and opposed-phase coronal-section MR images(FMPSPGR; TR=125 msec, TE=1.8, 4.2 msec) of the gallbladder were obtained, and differences in signal intensity thus determined. For proton MR spectroscopy of the gallbladder, a localized proton STEAM sequence was employed. A single voxel of 1-8 cm3 was placed at the center of the gallbladder cavity, peak areas at 0.8-1.6 ppm (lipid), 2.0-2.4 ppm, 3.2-3.4 ppm, 3.9-4.1 ppm, and 5.2-5.4 ppm were measured by proton MRS and the relative peak area ratios of peak 0.8-1.6 ppm/other peaks were calculated. The degree of correlation between signal intensity differences at MRI and the relative peak area ratio of lipid in proton MRS was estimated using the p-value and Pearson's correlation coefficient. Results: Signal intensity differences ranged from 11.3 to 43.4% (mean,268.9%), and the range of lipid peak area ratio at MRS was 0.10-0.97 (mean, 0.660.21). There was significant correlation between the two measured values (P=0.014, Pearson’s correlation coefficient=0.478). Conclusion: In normal cystic bile, signal intensity differences at in- and opposed-phase MRI and relative lipid peak area ratios at MRS varied, though both methods could be used diagnostically for measuring the lipid contents of body tissue.

Purpose: The purpose of this study was to evaluate change in the proton MR spectroscopic (1H-MRS) features of the liver according to changes in the severity of the chronic hepatitis spectrum (normal-chronic hepatitis-liver cirrhosis), and to determine the possibility of replacing liver biopsy by1 H-MRS. Materials and Methods: Sixty profiles of 1H-MRS features from 15 normal volunteers, 30 cases of chronic hepatitis, and 15 of liver cirrhosis were evaluated. All cases of chronic hepatitis and liver cirrhosis were confirmed by biopsy, and histopathologic disease severity was categorized according to Ludwig’s classification. Using the STEAM(STimulated Echo-Aquisition Mode) sequence, -MRS was performed. The ratios of peak areas of [glutamate+glutamine]/lipid, phosphomonoesters/lipid, [glycogen+glucose]/lipid, and [3.9-4.1ppm unknown peak]/lipid and their mean and standard deviation were calculated in normal, chronic hepatitis stages I and II, and early and late liver cirrhosis groups and the results were compared between these groups. One-way variable analysis was applied to the statistics. Results: Mean and standard deviation of phosphomonoesters/lipid in the normal, chronic hepatitis grades I and II, and early and late liver cirrhosis groups were , respectively, and [glycogen+ glucose]/lipid were , respectively. These results implied that the ratio of the above metabolites to lipid content increased according to increasing disease severity (p, respectively, and there was no correlation with disease severity. In the chonic hepatitis grades I and II, and early and late liver cirrhosis groups, the ratios for [3.9-4.1 ppm unknown peak]/lipid were , and these also increased according to increasing disease severity (p-MRS features of the liver. These results indicate that in cases of chronic hepatitis and liver cirrhosis, biopsy of the liver can be replaced by -MRS.

Purpose : The purpose of this study was to determine the proton MR spectroscopic features of liver cirrhosis and the different proton MR spectroscopic features between liver cirrhosis and the normal human liver by comparing the two different conditions. Materials and Methods : The investigation involved 30 cases of in-vivo proton MR spectra obtained from 15 patients with liver cirrhosis demonstrated on the basis of radiologic and clinical findings, and from 15 normal volunteers without a past or current history of liver disease. MR spectroscopy involved the use of a 1.5T GE Signa Horizon system (GE Medical Systems, Milwaukee, U.S.A.) with body coil. STEAM (STimulated Echo-Aquisition Mode) with 3000/30 msec of TR/TE was used for signal acquisition; patients were in the prone position and respiration was not interrupted. Cases were assigned to either the cirrhosis or normal group, and using the proton MR spectra of cases of in each group, peak changes occurring in lipids (at 1.3ppm), glutamate and glutamine (at 2.4 -2 .5ppm), phosphomonoesters (at 3.0 -3 .1ppm), and glycogen and glucose (at 3.4 -3 .9ppm) were evaluated. Mean and standard deviation of the ratio of glutamate + glutamine/lipids, phospho-monoesters/lipids, glycogen + glucose/lipids were calculated from the area of their peaks. The ratio of various metabolites to lipid content was compared between the normal and cirrhosis group. Results : The main characteristic change in proton MR spectra in cases of liver cirrhosis compared with normal liver was decreased relative intensity of lipid peak. Mean and standard deviation of ratio of glutamate + g-lutamine/ lipids, phosphomonoesters/lipids, glycogen + glucose/lipids calculated from the area of their peaks of normal and cirrhotic liver were 0.0204 0.0067 and 0.0693 0.0371 (p0.0090 and 0.0881 0.0276 (p0.0267 and 0.2325 0.1071 (p0 . 0 3 5 5 . Conclusion : Proton MR spectra of liver cirrhosis revealed decreased intensity of lipid with statistical signifi-cance compared with that of normal liver, and peak at 3.9 -4.1 ppm with unknown nature. In conclusion, liver cirrhosis can be diagnosed non-invasively by the analysis of observed proton MR spectroscopic features.

Purpose: To investigate the in vivo proton MR spectra of the bile of human gallbladder in its normal and diseased states and to compare the findings between the two groups. Materials and Methods: In vivo proton MRS was performed in 88 subjects comprising 33 healthy volunteers, 41 patients with gallstone, and 14 with distal common bile duct obstruction. For this, a clinical 1.5T system with a body coil and STEAM (STimulated Echo-Acquisition Mode) was used. We analyzed the MR spectra of normal and diseased gallbladder biles and tried to categorized the findings according to the significant peaks occuring within consistent ranges of chemical shift. We also compared the spectral patterns between normal and dis-eased bile. Results: Proton MRS showed four significant major peaks in normal and diseased human bile: peak 1 at 0.8 - 1.4 ppm, peak 2 at 3.2 -3.4 ppm, peak 3 at 3.9 -4.1 ppm, and peak 4 at 5.2 -5.4 ppm. In each group, peak 1 was most frequent(healthy volunteers, 91%, patients with gallstone, 100%, patients with distal common bile duct obstruction, 93%), but as compared with normal bile (peak 2, 36%, peak 3, 33%), in patients with gall-stone, peak 3 was more frequently seen (46%), and in those with distal common bile duct obstruction, peaks 2 (64%) and 3 (64 pattern II: peaks 1 and 2; pattern III: peaks 1 and 3; pattern IV: peaks 1, 2, and 3; pattern V: peaks 1 and 4; pattern VI: peak 3. In normal bile, the common MR spectral patterns were I (36%), II (27%), III, IV, VI, and V, in decreasing order of frequency. In patients with gallstone, however pattern I (44%) and pattern IV (34%) predominated, while in those with distal common bile duct obstruction, pattern IV (57%) Conclusion: The spectra of normal and diseased gallbladder bile obtained by in vivo proton MR spectroscopy varied, with some differences in spectral patterns between both groups.

Purpose : To evaluate the factors affecting intervertebral foramen stenosis and nerve root compression in spondylolytic spondylolisthesis. Materials and Methods : We investigated 120 intervertebral foramina of 60 patients with spondylolytic spondy-lolisthesis who had undergone lumbar MRI. A retrospective review of their MR images revealed the degree of intervertebral foramen stenosis and causes of nerve root compression. The relationship between disk height diminution following spondylolysis and degree of intervertebral foramen stenosis was also evaluated. Results : Forty eight of 60 patients showed a similar degree of intervertebral foramen stenosis, and in 12 pa-tients the degree of stenosis was different. In 110 intervertebral foramina, stenosis of both the superior and in-ferior compartments of intervertebral foramina was demonstrated. In 37 of 120 cases (30.8 %), stenosis was mild; in 44 of 120 (36.7 %) it was modcrate, and in 29 of 120 (24.2%) it was severe. Stenosis of the inferior com-partment was demonstrated in ten of 120 intervertebral foramina (8.3 %). Nerve root compression was caused by posterior bulging of the intervertebral disk (65/120), descent of the pedicle (51/120), an isthmic bony seg-ment above the site of spondylolysis (44/120), a bony spur formed at a spondylolytic site (11/120), and fibrocar-tilaginous callus at a spondylolytic site (5/48). In all cases there was degenerative change of the intervertebral disk at the affected level. There was no relationship between degree of disk height diminution and degree of intervertebral foramen stenosis (p>0.05). Conclusion : The degree of intervertebral foramen stenosis and causes of nerve root compression in spondy-lolytic spondylolisthesis are variable, and MRI demonstrates them precisely. There was no positive relation-ship between degree of nerve root compression at an intervertebral foramen and degree of spondylolysis and degeneration of an intervertebral foramen. The degree of nerve root compression is believed to be another cri-terion for describing spondylolytic spondylolisthesis.