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Biomedical subjects

Y Niio

Publications and source records attributed to Y Niio.

18 recordsLinked to original sources

Unusual early bile excretion from the liver in patients with fulminant hepatic failure as detected by Tc-99m-PMT hepatobiliary scintigraphy; comparison with Tc-99m-GSA scintigraphy.

In two females (58 and 14 years old) with fulminant hepatic failure, Tc-99m-PMT hepatobiliary scintigraphy was used to evaluate intrahepatic bile stagnation, and Tc-99m-GSA scintigraphy to evaluate hepatic functional reserve. In both patients, Tc-99m-PMT hepatobiliary scintigraphy showed unusual early bile excretion into the extrahepatic bile duct and small intestine within the first 30 min of imaging. These findings contradicted typical findings of intrahepatic bile stagnation of fulminant hepatic failure. The receptor index and blood clearance index determined from dynamic acquisition data on Tc-99m-GSA scintigraphy suggested a markedly decreased hepatic functional reserve. These findings were compatible with fulminant hepatic failure. A discrepancy was observed between the findings of hepatobiliary scintigraphy and those of Tc-99m-GSA scintigraphy. The pathological state of early bile excretion from the liver into the bile duct should be considered in fulminant hepatic failure.

Adolescent↗

Abnormal pulmonary accumulation of indium-111 chloride in pneumocystis carinii pneumonia as detected by bone marrow scintigraphy.

PURPOSE: Unusual pulmonary uptake of In-111 chloride in a patient with Pneumocystis carinii pneumonia and autoimmune hepatitis is described. METHOD: In-111 chloride bone marrow scintigraphy was performed to evaluate the bone marrow activity associated with pancytopenia in a 56-year-old woman with autoimmune hepatitis. RESULTS: An In-111 chloride bone marrow scan showed increased pulmonary uptake predominantly in both upper lung fields. P. carinii pneumonia was seen to be developing as an immunocompromised complication after treatment for autoimmune hepatitis. CONCLUSION: When In-111 chloride bone marrow scintigraphy shows increased uptake in the lungs of immunocompromised patients, a combined opportunistic inflammatory disease such as P. carinii pneumonia should be considered in the diagnosis.

Bone Marrow↗

[Assessment of a new non-invasive cerebral blood flow determination method using the brain uptake ratio of 99mTc-ECD].

We modified the method of calculating brain uptake ratio (BUR) reported previously, and devised a new non-invasive cerebral blood flow measurements for 99mTc-ECD that does not require blood sampling. This method yields BUR that is not influenced by the gamma camera type and the choice of acquisition-reconstruction conditions, when corrected by the SPECT/Planar cross calibration coefficient. A good correlation was observed between the BUR obtained by this method and the cerebral blood flow (CBF) obtained by the 123I-IMP continuous arterial blood sampling method. And based on these results, it is now possible to convert BUR to CBF. This method is applicable to small field type of gamma cameras, and it is expected to be useful as a routine test.

Brain↗

[Effect of the skull on brain perfusion SPECT imaging].

Because attenuation gradually decreases reconstructed counts from the periphery to the center portion of the object, the deep region far from the detector is not clearly observed if attenuation is not compensated. In brain perfusion SPECT, diagnosis is sometimes made using filtered back projection images without attenuation compensation (FBP). Brain perfusion SPECT has the unique characteristic that the radiopharmaceutical accumulates only within the brain and is never taken up by the surrounding skull. This study investigated the effect of skull on brain perfusion SPECT reconstructed with FBP. We theoretically derived the relation between the counts of brain and the linear attenuation coefficient of skull. It was found that the difference in reconstructed counts between the deep gray matter and peripheral gray matter decreased due to the existence of the skull. This result indicated that the deep gray matter was inclined to be visible if the FBP images were displayed according to relative counts normalized to the maximum count of each image. In order to confirm this, we made a numerical phantom with realistic human brain and skull contours on the basis of MR images from a normal volunteer. The linear attenuation coefficient of brain was assumed to be 0.15 cm-1, while that of skull was assumed to be 0.26 cm-1 (denoted as BONE+) or 0 cm-1 (BONE-). In accordance with the theoretical results, the deep gray matter of BONE+ images was more clearly observed than that of BONE- images, if these were displayed using the relative counts of each images. The physical phantom experiments also supported the theoretical and numerical phantom studies.

Cerebrovascular Circulation↗

[Combined scatter and attenuation correction for 201Tl myocardial perfusion SPECT using OS-EM algorithm].

There are two possible ways to obtain scatter-corrected images with the ML-EM (maximum likelihood expectation maximization) algorithm: one is the subtraction of scatter estimate si from projection data pi, and then (pi-si) is used for scatter-corrected projection data (denoted as SC(T)); the other method is the addition of scatter estimate si to the projections calculated from the reconstructed image without performing data subtraction (SC(E)). This paper investigated these two ML-EM algorithms of combined scatter and attenuation correction on 201Tl myocardial perfusion SPECT imaging. Scatter windows were placed one full width at half maximum (FWHM) below and above the photopeak centerline. The scatter fraction in the primary peak was estimated using trapezoidal approximation by the triple energy window method. Phantom and clinical images were reconstructed using 6 iterations of ordered subsets EM algorithm (OS-EM). A cylindrical phantom with a cold-rod insert and a heart/thorax phantom with liver insert were used to evaluate scatter and the attenuation compensation technique. A cylindrical phantom filled with uniform 201Tl solution was used to evaluate statistical noise. The percent root-mean-square uncertainty (%RMSU) was used as a quantitative measure of noise amplification. %RMSU showed that the SC(E) method amplified noise less in comparison with the SC(T) method, however, no significant difference in image quality was observed between the two methods. In conclusion, both the SC(T) and SC(E) methods provided significant and similar improvement in the removal of scatter in 201Tl myocardial perfusion SPECT imaging.

Absorption↗

Precision of the gallbladder ejection fraction obtained with Tc-99m-pyridoxyl-5-methyl-tryptophan (99mTc-PMT) hepatobiliary scintigraphy as compared with the contraction ratio in three-dimensional computed tomography.

UNLABELLED: The gallbladder ejection fraction (GBEF) obtained with Tc-99m-pyridoxyl-5-methyl-tryptophan (99mTc-PMT) hepatobiliary scintigraphy has been used as a parameter of gallbladder function. To determine the accuracy of GBEF, the relationship with the contraction ratio of the gallbladder (GBCR) obtained with three-dimensional helical computed tomography (3D-CT) was studied. PATIENTS AND METHODS: A normal volunteer, 8 patients suffering from cholecystolithiasis and a patient with gallbladder dyskinesia were examined. The percent initial dose (%ID) for the gallbladder and GBEF with hepatobiliary scintigraphy were used to compare the volume of the gallbladder and GBCR which was measured by 3D-CT. RESULTS: The %ID of the gallbladder was correlated with the volume of the gallbladder by 3D-CT (Y = 1.000X - 1.818, r = 0.928). GBEF was correlated well with GBCR by 3D-CT (Y = 0.916X + 6.296, r = 0.975). CONCLUSIONS: The %ID of the gallbladder obtained with hepatobiliary scintigraphy may be a good indicator of the volume of the gallbladder. The accuracy of GBEF was confirmed by comparison with 3D-CT examination. GBEF is considered a useful parameter of pathophysiological gallbladder function.

Adult↗

[Proposal on new formulas for renal depth in the technetium-99m-mercaptoacetyltriglycine (MAG3) scintigraphy].

UNLABELLED: Recently, camera-based techniques to measure effective renal plasma flow (ERPF) have become more popular than single plasma sample techniques because camera-based measurements avoid the necessity of delayed plasma samples and in vitro techniques. The measurements of ERPF are used to estimate the clearance of technetium-99m-mercaptoacetyltriglycine (MAG3). However, camera-based techniques are dependent on an accurate estimate of renal depth to correct for soft-tissue attenuation. Then, new formulas for renal depth correction of technetium-99m-MAG3 clearance in place of Tønnesen's, M. Ito's, K. Itoh's, and Taylor's methods were tried to establish in this paper. PATIENTS AND METHODS: Eleven hundred and seventy patients without any renal disease were objected. The data from measurement of renal depth using X-ray CT in supine position were analyzed statistically. RESULTS: The depths of right kidney (Dr) and left kidney (Dl) were 7.33 +/- 1.27 and 7.07 +/- 1.27 cm. The correlation coefficients between Dr and height (H) body weight (W), body surface area (BSA: W0.425 x H0.725 x 0.007184 m2), age, and abdominal thickness (Ta) were 0.275, 0.709, 0.615, 0.087, and 0.743. The correlation coefficients between Dl and H, W, BSA, age, and Ta were 0.269, 0.732, 0.629, 0.029, and 0.812. Ta had best correlation with both Dr and Dl. The calculation formulas for Dr and Dl using Ta were as follows: Dr = 0.32 x Ta + 0.87 cm, and Dl = 0.36 x Ta - 0.08 cm. On the other hand, the multiplex calculation formulas of Dr or Dl with H, W, and Ta were as follows: Dr = 0.18Ta + 8.54 x (W/H) + 0.75 (r = 0.768), and Dl = 0.26Ta + 5.90 x (W/H)-0.16 (r = 0.823). CONCLUSION: The new regression equations provide superior estimates of renal depth compared to conventional equations. Application of these new formulas into camera-based protocols to determine renal clearances may lead to more accurate measurements of ERPF using technetium-99m-MAG3 scintigraphy.

Adolescent↗

[Can 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) evaluate the renal function without blood sampling?: consensus report from multicenter study].

A multicenter study was undertaken in Japan to evaluate the correlation between the percentage of renal uptake of 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) estimated by the count-based gamma camera method and the blood clearance of 99mTc-MAG3. Twenty four centers were enrolled and 172 cases were finally analyzed in this study. The renal clearance of 99mTc-MAG3 (TER) was obtained by using a single blood sample taken at 44 min after injection. Comparison of TER and renal uptake provided a coefficient of correlation of 0.874; suggesting that sufficiently accurate quantification of renal function could be obtained from the renal uptake estimate by the gamma camera method. This study also showed that the comparison of renal function might be feasible among patients under the same protocols, although precise and careful consideration is required in each center.

Adolescent↗

[Preoperative evaluation of the limitation of hepatic resection using 99mTc-GSA (galactosyl human serum albumin) scintigraphy].

UNLABELLED: Preoperative evaluation of the operative indication of hepatic resection using the parameters obtained by 99mTc-GSA scintigraphy has been done. In particular, the accurate evaluation of the postoperative hepatic functional reserve essentially depends on these parameters. In the present study, a preoperative evaluation of postoperative hepatic functional reserve using 99mTc-GSA scintigraphy was performed in our operated cases retrospectively. PATIENTS AND METHODS: Thirty-eight patients who underwent hepatic resection were studied on 99mTc-GSA scintigraphy before and after operation. These patients were divided into two groups. Group A; had no postoperative complications (n = 31). Group B; had some postoperative complications (n = 7). Preoperative parameters of 99mTc-GSA liver scintigraphy (HH15, LU15) were calculated from the activities of liver and cardiac ROIs at 5 and 15 minutes after injection. The resection ratio (RR) was obtained by comparing the liver volumes which were calculated from the pre- and postoperative SPECT studies. The resectability indices (Res) were as follows: Res (LU15) = LU15 x (100-RR(%)/100, Res (HH15) = (1/HH15) x (100-RR (%)/100. RESULTS: There were statistically significant differences in the distribution of Res between A and B groups (p = 0.002, Mann-Whitney test). The values of Res, of which half of patients have complication, were 1.10 (Res (HH15)) and 16.4 (Res (LU15)). CONCLUSION: The resectability indices using 99mTc-GSA liver scintigraphy are useful for the preoperative evaluation of the limitation of hepatic resection.

Adult↗

[Fast two-compartment model analysis with 99mTc-GSA liver scintigraphy].

The use of numerical integration method (N. INT) was evaluated in determining parameters by two-compartment model analysis from liver scintigraphy. Among the 15 subjects, 14 had liver cirrhosis or chronic hepatitis, and one was normal. When using N.INT, the sum of two exponential functions on heart regression curve following intravenous injection of 99mTc-galactosyl human serum albumin (99mTc-GSA) was promptly calculated. The parameters obtained from N.INT, including transfer rate of 99mTc-GSA from extrahepatic blood to liver (k1), dissociation rate from liver to extrahepatic blood (k2), and excretion rate from liver to gallblader (k3), were significantly correlated with those obtained by the nonlinear least square method (NLS). k1/k2 was related with the maximum removal rate of 99mTc-GSA obtained from nonlinear five compartment model analysis (r2 = 0.705, n = 15) and also with the severity score of liver disease as classified by the First Department of Surgery, Mie University Medical School (r2 = 0.686, n = 13). In terms of the time required to obtain these parameters, including the blood retention rate of 99mTc-GSA at 15 min after injection (%ID15), N.INT was faster than the traditional method (NLS).

Aged↗

[Quantitative analysis of 99mTc-GSA liver scintigraphy with graphical plot method].

99mTc-galactosyl human serum albumin (99mTc-GSA) is a newly developed receptor-binding agent, specific for the asialoglycoprotein receptor, which resides exclusively on the plasma membrane of mammalian hepatocytes. Liver scintigraphy using 99mTc-GSA was performed on 65 patients with liver diseases. Dynamic data were obtained by gamma camera during 20 minutes after the intravenous injection of 3 mg (185 MBq) of 99mTc-GSA. The maximum removal rate of 99mTc-GSA (denoted as P(2)) was measured by two methods: nonlinear five-compartment model analysis adopting the Michaelis-Menten constant for the transfer of 99mTc-GSA from hepatic blood to receptor, and a graphical plot using compartmental dose curves. The graphical plot could estimate easily the maximum removal rate in terms of two data points of 0 and 1 minutes without nonlinear least squares and numerical integration. The results indicated that the maximum removal rate was decided immediately after the intravenous injection of 99mTc-GSA. Although 99mTc-GSA is recognized to accumulate nonlinearly on the liver, the rate constant P(2)*(1/min) of transfer from hepatic blood to the receptor was estimated by graphical plot, assuming a linear five-compartment model. P(2)*Km, which was given by the product of the rate constant P(2)* and the Michaelis constant Km, was well correlated with P(2). Next, for 99mTc-GSA liver scintigraphy, we applied a Patlak plot that was applicable to the linear system, and the rate constant Ku of transfer from extrahepatic blood to the liver was estimated. From the results of graphical plot, it was theoretically shown that Ku represented P(2). This was confirmed by clinical data.

Adult↗

Using Ga-67 scintigraphy in prostatic abscess.

The use of Ga-67 scintigraphy (Ga) in prostate inflammatory diseases may be restricted by the difficulty in distinguishing between the accumulation of Ga-67-citrate (Ga-citrate) in the lesion and feces. The diagnosis of prostatic abscess has been mainly made by other radiologic methods without scintigraphic studies and no finding of Ga has been reported. This patient demonstrated that coordinating the findings of Ga-citrate accumulation can be helpful in making a prompt diagnosis of a possibly fatal prostatic abscess, especially in those patients with poorly defined clinical symptoms and high risk factors.

Abscess↗

[A study of acquisition time using compartment analysis with 99mTc-GSA liver scintigraphy].

99mTc-galactosyl human serum albumin (99mTc-GSA) is a newly developed receptor-binding agent specific for the asialoglycoprotein receptor, which resides exclusively on the plasma membrane of mammalian hepatocytes. Liver scintigraphy using 99mTc-GSA was performed on 13 patients with liver disease. Dynamic data were obtained by gamma camera during 40 min after the intravenous injection of 3 mg (185 MBq) of 99mTc-GSA. Heart and liver time activity curves with acquisition times of 40,30 and 20 min were created, and two different compartment analyses were examined. One was a nonlinear five-compartment model adopting the Michaelis-Menten type for the transfer of 99mTc-GSA from hepatic blood to receptor, and the other was a linear five-compartment model assuming a linear rate constant (P(2)*) for the transfer of 99mTc-GSA. The maximum removal rate obtained by the nonlinear model, P(2), was found to be independent of the change in acquisition time, while the maximum removal rate obtained by the linear model, P(2)*.Km, which was given by the product of P(2)* and the Michaelis constant Km, increased with shortening acquisition times from 40 to 20 min. For both models, the liver blood flow rate decreased with shortening acquisition time. The maximum removal rate and liver blood flow rate obtained by the linear model were significantly correlated with those obtained by the nonlinear model. It was concluded that linear model with an acquisition time of 20 min was applicable to liver scintigraphy with 99mTc-GSA.

Adolescent↗

Evaluation of hepatic transport function by hepatobiliary scintigraphy.

The transport kinetics of [99mTc]-pyridoxyl-5-methyltryptophan were studied by three-compartment model analysis for hepatobiliary scintigraphy in 45 patients with chronic viral liver diseases. Three-compartment model analysis was studied using the time-activity curves of the regions of the heart, liver, and biliary tract and intestine (excretory compartment). The k12 (hepatic uptake rate constant), k21 (hepatic efflux rate constant), and ke1 (hepatic excretion rate constant) were calculated by the nonlinear least-squares method. Among the three parameters obtained by model analysis, k12 values more prominently differed among diseases and correlated well with blood tests such as total bilirubin, total bile acids, or 15 min retention of ICG. In conclusion, three-compartment model analysis of the hepatic handling of [99mTc]-pyridoxyl-5-methyltryptophan is useful in evaluating hepatic transport function. k12 is the most sensitive parameter for this.

Biliary Tract↗