Search PubMed⌕ Search

Biomedical subjects

A Iio

Publications and source records attributed to A Iio.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Diagnostic value of the reflux sign in cholescintigraphy after administration of a gallbladder contracting agent--a comparison with X-ray cholangiography].

This study reviewed 25 patients with the reflux sign in cholescintigraphy to assess its diagnostic value in evaluating biliary passage. After at least 4-hour fasting 5 mCi of 99mTcPMT or p-butyl IDA was injected intravenously and serial images were recorded before and after intramuscular injection of 10 micrograms of ceruletide diethylamine (caerulein). The reflux sign was determined positive when increased radioactivities in the left hepatic duct (minor reflux; MIR) or more peripheral intrahepatic ducts (major reflux; MAR) were recognized after injection of caerulein. The reflux sign was found in 28 of 237 (12%) studies. Direct and/or indirect X-ray cholangiograms were available in 25 (MIR; 15, MAR; 10). They included common bile duct (CBD) stone in 4, dilated CBD in 4, biliary dyskinesia (BD) in 4, chronic pancreatitis (CP) in 4, gallbladder (GB) stone in 3, duodenal ulcer (DU) in 2, CBD adenoma, pancreatic pseudocyst (PP), duodenal diverticle (DD), and acute cholangitis (AC) in 1 each. Their serum bilirubin levels were within normal limit in all but 2 at the time of cholescintigraphy. Transit time of radionuclides to the duodenum was found prolonged more than 60 min in 17 (68%) patients and persistent pooling in the CBD was found in 8 (28%) patients on scintigrams. The diameter of the CBD on X-ray cholangiogram was ranged 4 to 17 mm. Dilated CBD of more than 10 mm was found in 13 (52%) patients and apparent stenosis of the CBD in 6 (24%) patients. MAR seemed to correspond to increased diameter of the common hepatic more than 2 mm after caerulein injection in DIC. No abnormal findings in X-ray cholangiography was found in 10 (40%) patients including 3 with BD, 2 with GB stone, 2 with DU, 1 each with CP, PP, and AC. All those patients demonstrated MIR. We concluded that major reflux (MAR) sign was helpful in detecting an incomplete obstruction of the CBD, especially in patients with slightly to mildly dilated CBD.

Adult↗
PubMed1989

SPECT volume measurement using an automatic threshold selection method combined with a V filter.

The volume measurement of various organs by single photon emission computed tomography (SPECT) has generally been performed by summing up the voxels lying within the outer edge of the organ determined by thresholding as a function of the maximum reconstructed counts within a volume of interest. The optimum threshold level, however, is influenced by various factors. To eliminate this problem, Mortelmans et al. (1986) proposed to use an automatic threshold selection method (ATSM) based on discriminant criteria and to correct the errors induced by the imperfect system response using the method based on linear regression analysis, which has some problems in practical application. We tried to use ATSM combined with a V filter. The correlation coefficient (r) and the regression equation between the true (x) and the calculated volume (y) obtained by experimentation using 22 phantoms with a volume ranging between 26 ml and 380 ml were as follows: r = 0.994 and y(ml) = 1.015 x +1.09 using ATSM combined with a V filter, while r = 0.993 and y(ml) = 1.110 x +30.55 using only ATSM. The relative error between the true and the calculated volumes decreased significantly (P less than 0.01) from 37.7% +/- 26.9% to 5.5% +/- 4.2%. The results suggest that ATSM combined with a V filter is useful for correcting the errors caused by an imperfect system response, and is available and reliable for SPECT volume determination even when the organ volume is small.

Filtration↗
PubMed1989

A unified computer program for assessment of attenuation correction and data acquisition methods in single photon emission computed tomography (SPECT).

A computer based simulation program was developed to assess the usefulness of various attenuation correction algorithms and data acquisition methods in single photon emission computed tomography (SPECT) in a unified approach. The program analytically calculated projection ray sums from a mathematical model with various distributions of activities and either uniform or non uniform attenuation coefficients by using the line integrals including the effect of attenuation. Data acquisition starting at arbitrary angles, various acquisition angles, including a 180 degree scan and a non circular orbit of a gamma camera, including an elliptical orbit can readily be taken into consideration in our simulation program. To simulate non circular orbit data acquisition, the resolution dependence on the object distance from the collimator surface was incorporated into the simulation. This computer based simulation program allows various combinations of attenuation correction algorithms such as hybrid methods, and data acquisition methods can be evaluated under a large number of study conditions. The usefulness of this computer based simulation program is shown with several representative examples.

Algorithms↗
PubMed1989

Assessment of hepatic excretory function in chronic liver disease by hepatobiliary scintigraphy.

Hepatobiliary scintigraphy was performed in 23 normal subjects and 47 patients with chronic liver disease (chronic hepatitis; n = 27, liver cirrhosis; n = 20) to evaluate its availability as a test of liver function. After intravenous administration of Tc-99m N-pyridoxyl-5-methyl-tryptophan, the data were acquired for 60 min and the time-activity curves of ROIs (the heart and liver) were generated. In two compartment model simulation, the early blood clearance rate (kl), late blood clearance rate (km), hepatic uptake rate (ku) hepatic excretion rate (ke), and hepatic excretion T 1/2 were calculated. There was no significant difference in those four k values in normal and chronic hepatitis. However, in liver cirrhosis each of them, except km, was lower than in normal subjects. The kl value correlated closely with the indocyanine green plasma clearance test, whereas the ke and T 1/2 values were closely correlated with the level of serum bilirubins. Only hepatobiliary scintigraphy showed the excretory function of the liver quantitatively and the ke value was helpful in detecting hepatic excretory dysfunction early in chronic liver disease before serum bilirubins increased.

Adolescent↗
PubMed1989

A unified design algorithm of two-dimensional digital filters for radioisotope image processing.

A unified design algorithm of two-dimensional digital filters for radioisotope image processing based on the Fourier-Bessel transform and the weighted least-squares method is described. The algorithm presented here can treat the various kinds of two-dimensional digital filters in a unified approach. Design examples are presented and several graphs are included to show the relationships between the design parameters as an aid in practical applications. The application of the method in radioisotope image processing is also presented. Several low-pass, Wiener and band-pass filters were designed using the method and applied to some clinical data in nuclear medicine including SPECT images. The digital filter design technique proposed here is considered to provide a powerful tool for extraction of additional qualitative information and improvement of the quality of nuclear medicine images both in research and in routine clinical work.

Algorithms↗
PubMed1989

[Evaluation of serum pepsinogen I and II of patients with gastric cancer].

Serum pepsinogen levels were examined by immunoradiometric assay method for evaluating its clinical usefulness in gastric cancer. In patients with gastric cancer, serum PG-I tended to decrease but PG-II stayed normal level, resulting in low PG-I/PG-II ratio. Combination of PG-I and PG-I/PG-II discriminated 53.7% of gastric cancer, 70.6% of scirrhous type gastric cancer, and 66.7-100% of those arisen in the upper portion of the stomach, but 13.7% of normal subjects. As the aged normal subjects tended to show decreased PG-I/PG-II ratio (about 30% of the normal subjects aged over 40 years were discriminated as abnormal), the usefulness for detection of gastric cancer seems to be limited, but some types of gastric cancer such as scirrhous type or one arisen in the upper portion may be discriminated by this method. It is also suggested that this method may detect the recurrence of the cancer in some patients.

Adult↗
PubMed1988

Availability of tumor-antigen 4 as a marker of squamous cell carcinoma of the lung and other organs.

The serum level of tumor-antigen 4 (TA-4) was measured in 401 patients with squamous cell carcinoma (SCC) of various organs (76 lung, 82 esophagus, and 234 head and neck). The mean serum level of TA-4 in patients with lung SCC was 3.6 times higher than that in healthy controls and even higher in the advanced stages of disease (III, IV). In patients with benign diseases or other types of lung cancer, however, the TA-4 serum level was not different from the controls regardless of the clinical stage. During radiation therapy, the TA-4 levels in patients with lung SCC decreased with reduction in tumor size. It increased again markedly during recurrence. Similarly, patients with SCC of the esophagus and head and neck also showed elevated TA-4 levels but only at advanced stages and in recurrence. It was concluded that TA-4 is highly related to SCC not only of the uterine cervix but also of other organs and that serum level determinations are useful for monitoring therapeutic effects and recurrence of these diseases, despite some limitations.

Antigens, Neoplasm↗
PubMed1988

[An immunoradiometric assay of serum SCC antigen using a monoclonal antibody--a comparison with the conventional double antibody method].

The serum level of the squamous cell carcinoma-related antigen (SCC-Ag) has been measured by a new immunoradiometric assay (IRMA) method that has been recently developed by using a monoclonal antibody, and compared with the results obtained by the conventional double-antibody method using a polyclonal antibody. Both methods gave essentially the same results, that the serum SCC-Ag level was high in patients with squamous cell carcinoma of various organs when compared with other types of lung cancer or benign diseases. However, the percentages of the serum SCC-Ag level over the normal range were found to be higher by the new IRMA method than by the conventional method. This may be due to the improvement in sensitivity and accuracy of this newer method of assay, which also results in a considerable decrease in the normal range estimated in healthy subjects. Therefore, it has been concluded that this new method is more suitable than the conventional method for an early diagnosis of squamous cell carcinoma in all organs.

Antigens, Neoplasm↗
PubMed1987

Simulation and experimental study of respiratory motion effect on image quality of single photon emission computed tomography (SPECT).

The effect of respiratory motion on the image quality of single photon emission computed tomography (SPECT) was investigated by computer simulation and experimentation. In the computer simulation, the phantom was assumed to be cylindrical with a uniform background and a spherical cold or hot spot. To simulate respiratory motion, a cyclic linear motion parallel to the axis of rotation of a gamma camera was assumed. The contrast in the transaxial images was calculated for various respiratory amplitudes and its dependence on lesion size and object contrast was investigated. In the experiments, a moving phantom was used to simulate respiratory motion. The simulation and the experimental results were in good agreement within the range of statistical error. The effect on the lesion detectability was investigated using receiver operating characteristics (ROC) analysis, and a method for correcting respiratory motion was devised.

Computer Simulation↗
PubMed1987

A comparative study of attenuation correction algorithms in single photon emission computed tomography (SPECT).

A computer based simulation method was developed to assess the relative effectiveness and availability of various attenuation compensation algorithms in single photon emission computed tomography (SPECT). The effect of the nonuniformity of attenuation coefficient distribution in the body, the errors in determining a body contour and the statistical noise on reconstruction accuracy and the computation time in using the algorithms were studied. The algorithms were classified into three groups: precorrection, post correction and iterative correction methods. Furthermore, a hybrid method was devised by combining several methods. This study will be useful for understanding the characteristics, limitations and strengths of the algorithms and searching for a practical correction method for photon attenuation in SPECT.

Algorithms↗
PubMed1987

Monte Carlo estimates of absorbed dose rate in various tissues and organs.

A computer program based on the Monte Carlo technique was developed for calculation of absorbed dose rate in various tissues and organs. The accuracy of the program was tested by reproducing Berger's values of the specific absorbed fractions for point isotropic sources in water, and a good agreement with those obtained by the moments method was found within an error of several percent. In comparing with experiment and other Monte Carlo results, good agreement was also obtained within the range of statistical error. The absorbed dose rate for an 123I, 124I, 125I, 126I and 99mTc point source and their specific dose constants in various tissues and organs were calculated using this program. This computer program has the mass energy absorption and attenuation coefficients for 69 tissues and organs as a database file, and can be extended to various radionuclides used in nuclear medicine by adding their nuclear data to the program.

Humans↗