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2003 Volume 59 Issue 12 Pages
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Article type: Index
2003 Volume 59 Issue 12 Pages
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2003 Volume 59 Issue 12 Pages
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[in Japanese]
Article type: Article
2003 Volume 59 Issue 12 Pages
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Article type: Appendix
2003 Volume 59 Issue 12 Pages
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2003 Volume 59 Issue 12 Pages
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2003 Volume 59 Issue 12 Pages
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Article type: Appendix
2003 Volume 59 Issue 12 Pages
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Article type: Appendix
2003 Volume 59 Issue 12 Pages
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2003 Volume 59 Issue 12 Pages
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2003 Volume 59 Issue 12 Pages
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Article type: Appendix
2003 Volume 59 Issue 12 Pages
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Article type: Appendix
2003 Volume 59 Issue 12 Pages
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2003 Volume 59 Issue 12 Pages
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2003 Volume 59 Issue 12 Pages
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YOSHIHIRO IDA, [in Japanese], [in Japanese], [in Japanese]
Article type: Article
2003 Volume 59 Issue 12 Pages
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MSAAKI TAKAHASHI
Article type: Article
2003 Volume 59 Issue 12 Pages
1452-1461
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RYO TAKEUCHI
Article type: Article
2003 Volume 59 Issue 12 Pages
1462-1474
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MADOKA TATENO
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2003 Volume 59 Issue 12 Pages
1475-1481
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TOHRU HIRANO, [in Japanese], [in Japanese], [in Japanese]
Article type: Article
2003 Volume 59 Issue 12 Pages
1482-1493
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TOSIAKI MIYATI
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2003 Volume 59 Issue 12 Pages
1494-1501
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JUNICHIRO YOKOTA
Article type: Article
2003 Volume 59 Issue 12 Pages
1502-1507
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TOSIAKI MIYATI
Article type: Article
2003 Volume 59 Issue 12 Pages
1508-1516
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MASAYUKI SHIMOSEGAWA
Article type: Article
2003 Volume 59 Issue 12 Pages
1517-1519
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CHUDO KAZUSA
Article type: Article
2003 Volume 59 Issue 12 Pages
1520-1528
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MASATO UCHIKOSHI, TAKASHI UEDA, SHIGEO NISHIKI, KOUICHI SATOU, AKIHIKO ...
Article type: Article
2003 Volume 59 Issue 12 Pages
1529-1534
Published: December 20, 2003
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The purpose of this study was to evaluate the effect of inflow phenomenon on TrueFISP. We created a phantom using a vinyl tube and distilled water, and applied a pump-oxygenator to the phantom to obtain stationary flow. First, to evaluate the effect of inflow and the dephase phenomenon on signal intensity, the phantom was measured for the signal intensity of variable flow velocity. Second, the relation of TR/TE with signal intensity was analyzed. The results showed that a flow velocity of less than 15 cm/sec did not participate in signal reduction; however, signal intensity was reduced when flow velocity was more than 30 cm/sec. Moreover, the reduction of signal intensity was remarkable with a flow velocity of 50-100 cm/sec, which corresponds with arterial flow velocity. In the analysis of TR/TE, signal intensity was increased when TR of less than 5 ms was applied to the slow velocity of 15 cm/sec. Signal intensity was decreased when the same TR was applied to the high velocity of 50-100 cm/sec. When TR was 6-9 ms, peak signal intensity was recognized at the high velocity of 50-100 cm/sec. This peak, however, might correspond only to the inflow phenomenon, and steady state might have already collapsed. Based on these results, we concluded that TrueFISP is suitable for the imaging of slow flow velocity. A short TR of less than 5 ms was effective for obtaining high signal intensity. Our next goal will be to apply TrueFISP to MR venography, although further investigation will be necessary.
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YOSHIYUKI ISHIMORI, HIROHIKO KIMURA, TSUYOSHI MATSUDA, HIDEMASA UEMATS ...
Article type: Article
2003 Volume 59 Issue 12 Pages
1535-1541
Published: December 20, 2003
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We modified the multi-phase spoiled gradient recalled echo (SPGR.) pulse sequence using the double-echo MR technique for estimation of T_1 during the first pass of contrast agent, and examined its precision. In the first half of the pulse sequence, the flip angle was varied systematically to calculate static T_1 values. It was necessary to choose optimal flip angles to minimize the calculation error of static T_1 values. In the latter half of this sequence, changes in absolute T_1 were calculated using differences in signal intensities before and after the injection of contrast agent. The optimal flip angle was 20 degrees for precise conversion to T_1 values under the short TR(33.3 ms)condition. Double echo MR data were used to minimize the T_2 effect. The present method appears to be useful for quantitative estimation of dynamic contrast-enhanced MRI.
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KENCHI MACHIDA, MOTOHARU OOTSU, HIDEHARU NAKANO
Article type: Article
2003 Volume 59 Issue 12 Pages
1542-1547
Published: December 20, 2003
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PURPOSE: Cerebral blood blow (ml/100g/min) (CBF) and cerebral blood volume (%) (CBV) were determined in 102 patients (68 men and 34 women; average age, 55.6 years) with diagnostic cerebral blood flow accident. METHODS: CBF was obtained by xenon inhalation computed tomography (Xe CT) and transit time (TT) by perfusion CT. CBV was calculated under the expression CBV=CBF×TT. The patients were divided into three categories: mild (outpatient), moderate (inpatient), and serious (dead), and CBF and CBV were compared between categories. RESULTS: On regions of interest (ROI) in the thalamus, the value for mild cases was 58.8±10.4 ml/100g/min (CBF) and that for moderate cases was 40.2±19.4, a significant difference. In serious cases, CBV was decreased in the thalamus, but there was no difference in CBF between mild and moderate cases. CONCLUSION: CBV was useful for determining prognosis in severe cases of diagnostic cerebral blood flow accident.
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SHINTARO FUNABASAMA, YOSHITO TSUSHIMA, SHIGERU SANADA, KATSUMI INOUE
Article type: Article
2003 Volume 59 Issue 12 Pages
1548-1554
Published: December 20, 2003
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Aim: To improve liver-perfusion imaging by using the dual-input one-compartmental model. Methods: Single-level dynamic computed tomography (dynamic CT) was taken at the height of the hepatic hilum after a rapid intravenous injection using 40 ml of iodinated contrast material. From the time-density curve of each pixel on CT, we calculated blood-flow rate constants of liver inflow and outflow. For inflow, two constants were calculated at arterial and portal veins. We postulated that blood flow between hepatic vessels and the hepatic parenchyma could be analyzed by using the calculated constants, and made equations for liver perfusion mapping. The perfusion images obtained by this method were compared with those made by the maximum slope method. Results: We applied the method to a patient with hepatolithiasis. On dynamic CT, there was an abnormal enhancement pattern in the posterior segment of the liver. Perfusion CT images made by the dual-input onecompartment model demonstrated abnormal portal perfusion of the liver. In contrast, those made by the maximum-slope method did not represent the perfusion pattern well. Conclusion: The dual-input one-compartmental model makes it possible to obtain more detailed information on liver hemodynamics.
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YUHKO YAGISHITA, YUKIO OHGOSHI, MASAKI OHKUBO, KENICHI NAITO, TOMOKO I ...
Article type: Article
2003 Volume 59 Issue 12 Pages
1555-1560
Published: December 20, 2003
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In the present study, we quantitatively investigated the relationship between the signal intensity in a vessel and the duration of contrast enhancement as well as scan timing in 3D contrast-enhanced MR angiography using an elliptical centric phase-encoding technique. A tube phantom filled with Gd-DTPA, acting as a vessel, was taken out from the field of view during data acquisition, by using the "pause" function of our MR scanner (GE Signa, 1.5 Tesla), thereby simulating the presence and absence of a vessel. The shortening of the duration of enhancement corresponds to the delay of scan timing from the optimal point in the phase-encoding of the centric-ordering system. The signal intensity in a vessel (1-5 mm in diameter) decreased as the duration of enhancement became shorter and the diameter of the vessel decreased. When the number of partitions was 16 or 32 in a 128-mm-thick slab, the signal intensity obtained by the elliptical centric phase-encoding technique was almost the same as that obtained by the conventional centric phase-encoding technique. However, when the number of partitions was increased (64-124), and if the duration of enhancement was short, the signal intensity obtained by the elliptical centric phase-encoding technique was higher than that obtained by the conventional centric phase-encoding technique. In conclusion, in terms of the duration of enhancement and the delay of scan timing, the elliptical centric phase-encoding technique is superior to the conventional centric phase-encoding technique when the number of partitions in a slab for 3D MR angiography is increased.
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SATOSHI ODASHIMA
Article type: Article
2003 Volume 59 Issue 12 Pages
1561-1567
Published: December 20, 2003
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The brain uptake ratio (BUR) is useful for non-invasive cerebral blood flow measurements. To obtain this ratio requires setting an ROI on the aorta to draw the time-activity curve (TAG). Previously, the ROI has been manually set, in order to avoid two undesirable positionings: l) protrusion from the aorta and 2) overlap in a vein or lung. However, these manual methods are affected by operator subjectivity, which results in individual variations in TAG. In calculating the area under the curve (AUC), gamma fitting of TAG is also affected by operator subjectivity. These subjective operations are considered to be an important impediment to the reproducibility of AUC. Better reproducibility of AUC would lead to improved measurement of brain perfusion. In this study, two newly devised trials were undertaken: l) defining a system for setting ROI on the aorta; 2) and automatic gamma fitting for TAG. As a result of these trials, the individual variation in AUC among operators decreased, and the reproducibility of AUC was enhanced.
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YUMI KATAOKA, YOSHIHIRO IDA, TOSHIAKI NAKAI, SATOSHI YOSHIMI, AKANE HA ...
Article type: Article
2003 Volume 59 Issue 12 Pages
1568-1572
Published: December 20, 2003
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In our hospital, CT-perfusion was introduced in April, 2002. It is used to diagnose, to determine what treatment to use and to proghose cerebral blood flow after operation in super acute period brain infarct. At the beginning of the introduction, processing time and dosage for partial areas needed improvement. Therefore, we investigated the possibility of shorter processing time and lower dosage of radiation with the help of improvement in the analysis software as well as a different scan method. Two methods of reducing radiation dosage were examined. (1) The speed of X-ray rotation was slowed down; while photon per image was maintained, total mAs was lowered. (2) Continuation scan was replaced by intermission one. Analyzing time with older and newer version of analysis software was compared. The dosage was able to decrease by 25 % as a result of the rotation speed slowed down; it became further less by 50% with the intermission scan. Processing such as the vein extraction was automated by using new analysis software and successfully shorten the analysing time without damaging the reliability of analyses. We forecast that more clinical research on further lowering dosage and stabilization of analyzing will enable us to provide better information.
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AKIO NAGAKI, KOUICHI KOBARA, NORIKAZU MATSUTOMO
Article type: Article
2003 Volume 59 Issue 12 Pages
1573-1579
Published: December 20, 2003
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We developed a quantification analysis software program for measuring regional cerebral blood flow (rCBF) at rest and under acetazolamide (ACZ) stress by the modified split-dose (MSD) method with iodine-123 N-isopropyl-p-iodoamphetamine (IMP) and compared the rCBF values measured by the MSD method and by the split dose ^<123>I-IMP SPECT (SD) method requiring one continuous withdrawal of arterial blood. Since the MSD method allows the input of two arterial blood sampling parameter values, the background subtraction procedure for obtaining ACZ-induced images in the MSD method is not identical to the procedure in the SD method. With our software program for rCBF quantification, the resting rCBF values determined by the MSD method were closely correlated with the values measured by the SD method (r=0.94), and there was also a good correlation between the ACZ-induced rCBF values obtained by the MSD method and by the SD method(r=0.8l). The increase in rCBF under ACZ stress was estimated to be approximately 26% by the SD method and 38% by the MSD method, suggesting that the MSD method tends to overestimate the increase in rCBF under ACZ stress in comparison with the SD method, but the variability of the rCBF values at rest and during ACZ stress analyzed by the MSD method was smaller than the variability with the SD method. Further clinical studies are required to validate our rCBF quantification analysis program for the MSD method.
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HIROYUKI YAMAMOTO, TAKAFUMI MORIYA, NOBORU SHIRAGA
Article type: Article
2003 Volume 59 Issue 12 Pages
1580-1585
Published: December 20, 2003
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CT-perfusion (CTP) examination was performed in 30 cases of acute cerebral infarction (ACI) caused by middle cerebral artery (MCA) occlusion. Data were analyzed using cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). The results of the affected side were compared with those of the other side in terms of relative value and difference. A high correlation in relative value was found between CBF and CBV (r=0.81) and in both the relative (r=0.76) and difference (r=0.77) value between CBF and MTT. No correlation was seen between CBV and MTT. The time-density curve, along with CBF, CBV, and MTT, was classified into three patterns of ischemic brain damage: collateral, delayed, and flat patterns. In conclusion, CT-perfusion examination is useful for determining a treatment plan in ACI.
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Article type: Appendix
2003 Volume 59 Issue 12 Pages
1586-1587
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Article type: Appendix
2003 Volume 59 Issue 12 Pages
1588-1590
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2003 Volume 59 Issue 12 Pages
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Article type: Appendix
2003 Volume 59 Issue 12 Pages
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Article type: Appendix
2003 Volume 59 Issue 12 Pages
1591-1592
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Article type: Appendix
2003 Volume 59 Issue 12 Pages
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Article type: Appendix
2003 Volume 59 Issue 12 Pages
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2003 Volume 59 Issue 12 Pages
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2003 Volume 59 Issue 12 Pages
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Article type: Appendix
2003 Volume 59 Issue 12 Pages
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