K. Yamakado

Percutaneous radiofrequency ablation with transarterial embolization is useful for treatment of stage 1 renal cell carcinoma with surgical risk: results at 2-year mean follow up.

Objectives:  Despite laparoscopic partial nephrectomy and laparoscopic cryotherapy being performed lately, an even less invasive treatment would be desirable in high‐risk patients. Under local anesthesia with i.v. sedation, we were able to perform percutaneous radiofrequency ablation (RFA) combined with renal arterial embolization for unresectable stage 1 (T1NoMo) renal cell carcinoma (RCC). We evaluated the feasibility, safety and therapeutic effects of this technique after a 2‐year mean follow up.

Serial change of iodine-123 metaiodobenzylguanidine (MIBG) myocardial concentration in patients with dilated cardiomyopathy

Serial change of the metaiodobenzylguanidine iodine-123 (123I-MIBG) myocardial concentration was investigated in patients with dilated cardiomyopathy (DCM). Eight DCM patients and 6 control subjects were examined. After the injection of thallium-201 and 123I-MIBG, planar chest images were obtained simultaneously for both tracers in every 30–60 min over 5 h. Serial changes of myocardial uptake ratio (MUR) were compared for both tracers. In DCM, the initial MUR of 123I-MIBG did not differ significantly from that of the controls. The washout of 123I-MIBG from the myocardium, however, was significantly increased in DCM. In particular, the decrease in the early phase (15–45 min) was significantly larger in DCM than in the controls (21.2%±7.5% vs. 5.3%±4.0%, P <0.01), showing a significant negative correlation with the left ventricular ejection fraction (r = −0.72 P < 0.05). For 201TI, neither the initial MUR nor the washout rate different significantly between the two. Thus, an early rapid decrease of the 123I-MIBG myocardial concentration might characterize DCM and reflect the severity of this disease.

Quantitative analysis of scatter- and attenuation-compensated dynamic single-photon emission tomography for functional hepatic imaging with a receptor-binding radiopharmaceutical

A new method for quantitative liver study was developed using the tracer technetium-99m diethylene triamine penta-acetic acid-galactosyl human serum albumin (99mTc-GSA), an analog ligand of the asialoglycoprotein receptor, which is a hepatocyte surface receptor specific for galactose-terminated glycoproteins. For quantitative dynamic single-photon emission tomographic (SPET) studies, attenuation compensation using transmission computed tomography (TCT) and the triple energy window (TEW) scatter compensation method were evaluated. As the TCT source, we used an uncollimated multi-tube source with the TEW scatter compensation method. To verify the accuracy of cross-calibrated SPET values as compared with measured radioactivities, we performed SPET of a cylindrical water pool phantom which contains seven hot rods filled with different concentrations of99mTc activities, simulating the scan conditions in human studies. The results of the phantom studies showed good linearity and accuracy of the SPET values, withR2=0.993 and a regression line ofy=0.941x+5.48. From the analysis of a kinetic model based on a one-compartment model, focussing on the initial stage of several minutes after99mTc-GSA injection and taking the physiological expression presented in a three-compartment analysis into account, we introduced the Rutland equation (Patlak plot) in the99mTc-GSA study by which the overall and regional effective hepatic blood flow (EHBF) and hepatic blood pool volume were determined. Preliminary clinical evaluations were performed for four normal male subjects (23–35 years of age) and one patient. Forty sequential 30-s dynamic SPET acquisitions were obtained for a period of 20 min following the intravenous injection of99mTc-GSA with venous blood sampling at 10 min. After scatter compensation, the SPET images were reconstructed with attenuation compensation using an attenuation map obtained from TCT. The average normal value for the total EHBF was 468±83 ml/min and that for the hepatic blood pool volume, 777±123 ml. Functional images of the distribution of regional values of EHBF (ml/min/voxel) and hepatic blood pool volume (ml/voxel) were also generated corresponding to the original SPET images. The EHBF images showed regional liver function, higher in the right lobe than the left lobe in the normal cases, and the heptic blood pool volume images showed the distribution of intensified high values along major vascular structures. Receptor imaging with99mTc-GSA using the Rutland method and dynamic SPET with scatter and attenuation compensation is an effective technique that allows the evaluation of total and regional hepatic functional parameters (EHBF, hepatic blood pool) in vivo.