This system with a flexible suture for preoperative localization has a high success rate.

RF ablation seems to be a promising treatment for malignant thoracic tumors.

The US, MR, and dynamic MR findings in four patients with sclerosing stromal tumor of the ovary are reported. US showed a tumor with multilocular cystic components and irregularly thickened septa and tumor walls or a solid tumor including several small cystic components. On T2-weighted MR images, signal intensities of the cystic components were high and those of the solid components were inhomogeneous, ranging from intermediate-high to high. Dynamic MRI demonstrated marked early enhancement of the solid components.

A new tissue-equivalent MRI phantom based on carrageenan gel was developed. Carrageenan gel is an ideal solidifying agent for making large, strong phantoms in a wide variety of shapes. GdCl 3 was added as a T 1 modifier and agarose as a T 2 modifier. The relaxation times of a very large number of samples were estimated using 1.5-T clinical MRI equipment. The developed phantom was found to have a T 1 value of 202-1904 ms and a T 2 value of 38 -423 ms when the GdCl 3 concentration was varied from 0 -140 mol/kg and the agarose concentration was varied from 0 -1.6% in a carrageenan concentration that was fixed at 3%. The range of measured relaxation times covered those of all types of human tissue. Empirical formulas linking the relaxation time with the concentration of the modifier were established to enable the accurate and easy calculation of the modifier concentration needed to achieve the required relaxation times. This enables the creation of a phantom having an arbitrary combination of MRI phantoms are useful for calibrating and checking imaging equipment, developing new systems and pulse sequences, and training MRI operators. To be useful in these roles, the material used to make MRI phantoms should 1) have relaxation times similar to those of human tissue; 2) provide uniform relaxation times throughout the phantom itself; 3) be strong enough to enable the fabrication of a "torso" without the use of physical reinforcements; 4) allow the production of phantoms in the shapes and sizes of human organs; 5) be easy to handle; and, 6) remain chemically and physically stable over extended periods.There have been several attempts to create solid materials for MRI phantoms. Former candidates have included agarose (1-5), agar (6,7), polyvinyl alcohol (PVA) (8), gelatin (9,10), TX-150 (11), TX-151 (12), and polyacrylamide (13). These gel phantoms usually contained additives such as paramagnetic ions to control the T 1 relaxation times. The most versatile phantoms are probably the paramagnetically doped gels that are based on agarose (1-5) or agar (6,7). In these systems, the T 1 relaxation times can be easily modulated by varying the concentrations of the paramagnetic ions, whereas the T 2 relaxation times are primarily a function of the gelling agent concentration. In a phantom that is based on polyacrylamide gel (13), both the T 1 and T 2 relaxation times can be modulated simultaneously by varying the concentration of the gel without the paramagnetic ions. These phantoms are easy to prepare and can be made with a wide range of T 1 and T 2 relaxation times including those of human tissue. To create a phantom with a human-like T 2 relaxation time of about 40 -150 ms, however, the concentration of agar, agarose, and polyacrylamide must be about 1.5-3.0, 0.8 -4.0, and 17-30%, respectively. To create a phantom having a long T 2 relaxation time, the concentration would be so low that the gel would not solidify sufficiently. A PVA gel phantom can offer the appropriate physical characteristics because it is as hard as the st...

It is extremely important to have a good grasp of the acceptable limit of hepatectomy before operation because postoperative liver failure can take a fatal course; however, baseline data on the limit of hepatectomy have not been clearly defined. We therefore evaluated and compared the predicted remnant liver function obtained by computed tomography(CT) and technetium-99m diethylenetriamine penta-acetic acid-galactosyl human serum albumin (99mTc-GSA) liver scintigraphy in order to obtain precise data regarding remnant liver function before hepatectomy. We investigated 20 patients undergoing hepatectomy using the clearance rate of indocyanine green (KICG) as a parameter, and compared the predicted postoperative KICG obtained by CT and by transaxial single-photon emission tomographic (SPET) images acquired by 99mTc GSA liver scintigraphy before hepatectomy. In GSA studies, based on time-activity curves for the heart and liver, we compared HH15 (heart activity at 15 min divided by heart activity at 3 min), LHL15 (liver activity at 15 min divided by heart plus liver activity at 15 min) and KL (obtained from the time-activity curve for the liver) in 103 patients. In 58 patients without increased serum bilirubin, KL was compared with KICG. In four patients, occlusion of the right portal vein was performed with the aim of carrying out secondary hepatectomy, and changes in liver volume were compared between CT and 99mTc GSA liver scintigraphy. The correlation coefficient between the postoperative KICG predicted by CT and the actual postoperative KICG was rather poor, at r = 0.569 (P < 0.05); that between the postoperative KICG predicted by 99mTc GSA liver scintigraphy and the actual postoperative KICG was good, at r = 0.788 (P < 0.01); correlations between KL and HH15 and between KL and LHL15 in 103 patients were very good or good, at r = 0.906 (P < 0.001) and r = 0.807 (P < 0.001), respectively, and that between KL and KICG in 58 patients was very good, at r = 0.916 (P < 0.001). In all four cases of right portal vein occlusion, the remnant liver volume ratio was markedly increased after occlusion in GSA compared with CT, and the postoperative KICG predicted by GSA after occlusion was closer to the actual postoperative KICG than that predicted by CT. It is concluded that 99mTc GSA liver scintigraphy is useful for predicting remnant liver function before hepatectomy and for evaluating changes in regional liver function after occlusion of the portal vein unilaterally.