Yoshio Kuniyasu

Compartmental analysis of asialoglycoprotein receptor scintigraphy for quantitative measurement of liver function: A multicentre study

A multicentre study on multicompartmental analysis of hepatic scintigraphy using technetium-99m labelled galactosyl serum albumin (GSA), which binds to the asialoglycoprotein receptor, was carried out at seven institutions in Japan. Seventy-four patients with liver disease received 3 mg (185 MBq) of99mTc-GSA by intravenous injection. Sequential scanning was performed 30 min after injection to obtain anterior images of the heart and liver, followed by single-photon emission tomography (SPET). The indices included in this analysis were hepatic blood flow (Q) and maximal receptor binding rate (Rmax), which showed a good correlation with semiquantitative ratio indices for99mTc-GSA, namely the retention rate in blood (HH15) and the hepatic uptake rate (LHL15).Q andRmax also showed a significant correlation with other measures of hepatic function. When patients were grouped according to the severity of chronic liver damage (hepatocellular functional damage),Q was reduced in the moderate and severe groups, whileRmax was reduced in proportion to the functional stage. Both parameters showed no inter-institution difference using analysis of co-variance with the functional stage as a co-variant. With regard to the hepatic uptake rate, anterior planar images and SPET images gave similar results forQ andRmax. Acquisition times of 15 or 30 min provided the same results. The multicopartmental model analysis permitted comparable results to be obtained at institutions using different gamma cameras, and is therefore considered a universally applicable method. These results indicate thatQ andRmax are useful general indices for evaluating the function reserve capacity of the liver.

Dual-time point scanning of integrated FDG PET/CT for the evaluation of mediastinal and hilar lymph nodes in non-small cell lung cancer diagnosed as operable by contrast-enhanced CT

PURPOSE To evaluate whether dual-time point scanning with integrated fluorine-18 fluorodeoxyglucose ((18)F-FDG) positron emission tomography and computed tomography (PET/CT) is useful for evaluation of mediastinal and hilar lymph nodes in non-small cell lung cancer diagnosed as operable by contrast-enhanced CT. MATERIALS AND METHODS PET/CT data and pathological findings of 560 nodal stations in 129 patients with pathologically proven non-small cell lung cancer diagnosed as operable by contrast-enhanced CT were reviewed retrospectively. Standardized uptake values (SUVs) on early scans (SUVe) 1h, and on delayed scans (SUVd) 2h after FDG injection of each nodal station were measured. Retention index (RI) (%) was calculated by subtracting SUVe from SUVd and dividing by SUVe. Logistic regression analysis was performed with seven kinds of models, consisting of (1) SUVe, (2) SUVd, (3) RI, (4) SUVe and SUVd, (5) SUVe and RI, (6) SUVd and RI, and (7) SUVe, SUVd and RI. The seven derived models were compared by receiver-operating characteristic (ROC) analysis. k-Fold cross-validation was performed with k values of 5 and 10. p<0.05 was considered statistically significant. RESULTS Model (1) including the term of SUVe showed the largest area under the ROC curve among the seven models. The cut-off probability of metastasis of 3.5% with SUVe of 2.5 revealed a sensitivity of 78% and a specificity of 81% on ROC analysis, and approximately 60% and 80% on k-fold cross-validation. CONCLUSION Single scanning of PET/CT is sufficiently useful for evaluating mediastinal and hilar nodes for metastasis.

Implementation and quantitative evaluation of analytical methods for attenuation correction in SPECT: a phantom study

Three differing exact methods of inverting the two-dimensional (2D) exponential Radon transform were implemented and evaluated quantitatively with a phantom study. The phantom had the shape of a pie-chart divided into six cavities, each 480 ml in volume and 10 cm in height, that were symmetrically positioned in a cylinder that was 20 cm in diameter and 10 cm in height. This phantom tests for linearity between true activity concentration and measured activity concentration, and it is denoted as a linearity phantom in the present study. Each cavity contained a different concentration of a homogeneous solution of 99mTc (74, 148, 222, 296, 370 and 444 kBq ml(-1)). Data acquisition was performed with two energy windows: a 20% photopeak energy window set symmetrically over the 140 keV of 99mTc and a secondary 5% energy window set over the 122 keV peak. We optimized a triple-energy window scatter correction method for a gamma camera-collimator system to obtain accurate scatter-corrected projections. A circular ROI 3 cm in diameter was identified over each cavity region, and count density (counts per pixel) was calculated. This value was converted to activity concentration (kBq ml(-1)) using a cross-calibration coefficient between SPECT counts and the gamma well counter. The relation between true activity (x) and measured activity concentration (y) was fitted to a line using the least-squares method. Regression lines were y = 0.63 + 1.0255x (R2 = 0.9987), y = -2.62 + 1.0278x (R2 = 0.9995), and y = 0.092 + 1.0241x (R2 = 0.9989) for the Bellini, Inouye and Metz-Pan methods respectively. In another phantom study using two different types of phantoms, contrast of a cold region in the two was 96% and 101% for all three methods. Combined optimized scatter correction and analytical attenuation correction methods achieve good accuracy in quantification of activity distribution with a uniform attenuating medium.

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.

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

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.

An experimental study of deep-vein thrombosis using 99mTc-fibrinogen

The in vivo and in vitro behavior of 99mTc-fibrinogen was investigated in rats, as well as the relationship between its incorporation into thrombi and gamma imaging in deep-vein thrombosis. 99mTc-Fibrinogen manifested satisfactory physicochemical and biological properties, and its in vivo stability was demonstrated by a high ability to clot in the circulating blood. High ratios of thrombus-to-blood were found between 4 and 24 h after the injection of this agent in 30-min thrombi. Among 30-min to 7-day thrombi, the highest ratio was found in 1-day thrombi and the lowest in 7-day thrombi. Hot spots on the scan were clearly visualized in fresh thrombi. It is concluded that 99mTc-fibrinogen is a very useful and promising scanning agent for the diagnosis of active thrombosis.

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.

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.

The diagnostic evaluation of hepatobiliary scintigraphy with 99mTc-PMT in acute cholecystitis.

99mTc-PMTを用いた肝胆道スキャンによる急性胆嚢炎の診断について, 胆摘後症例を除く良性胆道疾患80例を対象に検討した.急性胆嚢炎の診断基準として従来用いられてきた胆嚢描画の有無では, specificity 63%, efficiency72%, predictability positive test (有病正診率) 45%であった.胆嚢描画陰性に加え腸管運動低下を診断基準に加えるとspecificity 97%, efficiency 97%, predictability positive test 90%と診断能が有意 (p<0.01) に向上した.従って, 急性胆嚢炎の診断基準に, 腸管運動低下所見の有無を加味することが意義あることと言える.