Masaki Matsushita

Detection of hypervascular hepatocellular carcinoma by dynamic MRI and dynamic spiral CT

Objective Our goal was to evaluate the detectability of hypervascular hepatocellular carcinomas (HCCs) by multislice dynamic MRI and dynamic spiral CT. Materials and Methods Prior to transcatheter arterial chemoembolization (TACE) with iodized oil, the liver was subjected to T1− and T2-weighted SE-MRI, multislice dynamic MRI after intravenous bolus injection of Gd-DTPA, early phase imaging with spiral CT (dynamic spiral CT) after intravenous bolus injection of contrast medium (at a rate of 2 or 3 ml/s), and delayed phase CT in 64 patients with 208 HCC nodules. The detectability of HCCs by MRI and CT was evaluated retrospectively compared with CT after TACE as a gold standard. Results The detectability of nodules < 1 cm in diameter was superior with dynamic MRI (67%) and dynamic spiral CT (50%) in comparison with SE-MRI (26%) and delayed phase CT (11%) (p < 0.01). The detectability of these tumors with dynamic MRI was significantly superior to that with dynamic spiral CT using an injection rate of 2 ml/s (p < 0.01), but not significantly different from that of dynamic spiral CT using a rate of 3 ml/s. Conclusion Dynamic MRI and dynamic spiral CT are comparable for detecting hypervascular intrahepatic metastases of HCC.

Sensitivity in Detection of Hypervascular Hepatocellular Carcinoma by Helical CT with intra-arterial injection of contrast medium, and by helical CT and MR Imaging with intravenous injection of contrast medium

Purpose: to determine the effectiveness of i.a. contrast-enhanced helical CT and of i.v. contrast-enhanced helical CT and MR imaging, in detecting hyper-vascular hepatocellular carcinoma (HCC) Material and Methods: Fifty patients with 125 hypervascular HCC nodules underwent helical CT both during arterial portography (CTAP) and during hepatic arteriography (CTHA). Helical CT and MR imaging of the entire liver with i.v. administration of contrast medium were also performed. Helical CT images were obtained at 30–33 s (arterial-phase CT) and at 5 min (equilibrium-phase CT) after the initiation of an i.v. bolus injection of contrast medium. After T1- and T2-weighted spin-echo MR imaging, gradient-echo images during breath-holding were obtained prior to and 20 s, 1 min, and 2 min after the bolus administration of 0.1 mmol/kg of gadopentetate dimeglumine (dynamic MR). the sensitivity and positive predictive value of the various techniques were evaluated and compared Results: in terms of sensitivity for hypervascular HCC nodules of less than 1 cm in diameter, CTAP (90%) and CTHA (88%) were significantly superior to dynamic MR imaging (44%), arterial-phase CT (39%), spin-echo MR imaging (20%), and equilibrium-phase CT (7%) (p>0.001). However, there was no significant difference in the techniques with regard to the detection of lesions equal to or more than 2 cm in diameter Conclusion: for detecting small hypervascular HCCs, helical CT with i.a. contrast enhancement is superior to helical CT and MR imaging with i.v. enhancement

Detectability of hypervascular hepatocellular carcinoma by arterial phase images of MR and spiral CT.

The ability of arterial phase images of breath-hold MR imaging and spiral CT to detect hypervascular hepatocellular carcinomas (HCCs) was evaluated. Prior to transcatheter arterial chemoembolization (TACE) with iodized oil, MR images and spiral CT during i.v. bolus injection of contrast medium (IV-MR imaging and IV-spiral CT) and spiral CT during intraarterial injection of contrast media through catheter (IA-spiral CT) of the entire liver were obtained in 24 consecutive patients with 93 HCCs. In the detection of HCCs less than 1 cm in diameter, IA-spiral CT (87.3%) was superior to IV-MR imaging (63.5%) and IV-spiral CT (54.0%) (p < 0.001). There was no significant difference in detectability in any tumor size between IV-MR imaging and IV-spiral CT. IA-spiral CT was the best for detecting hypervascular HCCs, and there was no significant difference between IV-MR imaging and IV-spiral CT.

Heavy Fermion State in YbIr2Zn20

We measured the high-field magnetization and de Haas–van Alphen (dHvA) oscillations for YbIr 2 Zn 20 with a cubic crystal structure, together with the electrical resistivity and magnetic susceptibility. The magnetic susceptibility χ with an effective magnetic moment of Yb 3+ becomes temperature-independent at low temperatures, with a broad peak at T χmax =7.4 K for H ∥ . The corresponding magnetization indicates a metamagnetic transition at H m =120 kOe, consistent with a T χmax vs H m relation in the Ce- and U-based heavy fermion compounds. The large cyclotron masses of 4–27 m 0 are detected in the dHvA experiment, and are found to be reduced at magnetic fields higher than H m =120 kOe. The resistivity follows the Fermi liquid relation ρ=ρ 0 + A T 2 under magnetic field, and the \(\sqrt{A}\) value is also found to have a maximum at H m as a function of magnetic field. From the present experimental results, together with the results of 4 f -itinerant energy band calculations, the 4 f electrons are fou...

Metamagnetic Behavior in Heavy-Fermion Compound YbIr2Zn20

The metamagnetic behavior in the heavy-fermion compound YbIr 2 Zn 20 with a cubic structure was studied by magnetization, de Haas–van Alphen (dHvA) oscillation, magnetoresistance, specific heat, thermal expansion, and magnetostriction measurements in single-crystalline samples. A metamagnetic anomaly at H m ≃100 kOe was found to exist in all field directions in the cubic crystal structure. The cyclotron effective mass m c * , the coefficient A in the Fermi liquid relation of electrical resistivity ρ=ρ 0 + A T 2 , and the electronic specific heat coefficient C / T indicate a peak at the metamagnetic field H m . The negative thermal expansion and negative volume magnetostriction suggest that the valence of the Yb ion gradually changes from a 4 f -itinerant state to a trivalent state with increasing magnetic field, and an almost trivalent state is realized above the metamagnetic field H m . On the other hand, the topology of the Fermi surface is approximately unchanged below and above H m in the dHvA experiment.

Strong Field Quenching of the Quasiparticle Effective Mass in Heavy Fermion Compound YbCo2Zn20

We found a metamagnetic like anomaly at H m ≃5 kOe in a heavy fermion compound YbCo 2 Zn 20 below the characteristic temperature T χ max =0.32 K where the ac-susceptibility shows a broad peak, suggesting that an electronic state with a very low Kondo temperature is realized. Interestingly, the metamagnetic like behavior was observed as two peaks at 4.0 and 7.5 kOe at 95 mK in the magnetic field dependence of the electronic specific heat C / T . The extremely large values of the electronic specific heat coefficient γ≃8000 mJ/(K 2 ·mol) and A =160 µΩ·cm/K 2 in the electrical resistivity ρ=ρ 0 + A T 2 at H =0 kOe are most likely due to the very low Kondo temperature. The \(\sqrt{A}\) value was, however, found to be strongly reduced from \(\sqrt{A}=12.6\) (µΩ·cm/K 2 ) 1/2 at 0 kOe to 0.145 (µΩ·cm/K 2 ) 1/2 at 150 kOe. Therefore, we considered that the corresponding cyclotron effective mass m c * , which was determined from the temperature dependence of the de Haas–van Alphen (dHvA) amplitude, is also reduced ...

Hepatocellular carcinoma treated with radio frequency ablation: An early evaluation with magnetic resonance imaging

To determine the usefulness of nonenhanced T1‐weighted spoiled gradient‐recalled acquisition in the steady‐state (SPGR) MRI in the early assessment of the efficacy of radio frequency (RF) therapy for hepatocellular carcinoma (HCC).

Fermi Surface Property and Characteristic Crystalline Electric Field Effect in PrIr2Zn20

We measured the de Haas–van Alphen (dHvA) oscillations, electrical resistivity, magnetic susceptibility, magnetization, and specific heat of PrIr 2 Zn 20 , which has recently been suggested as a he...

Effective cases of transcatheter arterioportal chemoembolization with high-dose iodized oil for hepatocellular carcinoma

By administering an excessive amount of iodized oil via the hepatic artery, anticancer drugs in the iodized oil flow into the portal vein through the arterioportal communication. This phenomenon permits chemotherapy against extracapsular infiltration by a hepatocellular carcinoma (HCC) nourished by the portal blood flow. From May 1983 through July 1992, 240 cases of HCC underwent transcatheter arterioportal chemoembolization (TAPCE) with more than 5 ml of iodized oil (mean, 15 ml) in our hospital. In all, 32 patients survived for more than 3 years, and the factors favoring the efficacy of TAPCE therapy were investigated. Doxorubicin (mean, 46 mg) was given to 31 patients and 20 mg mitomycin C was given to 1 patient. The patients included one Stage 1 case, 13 Stage 2 cases, 17 Stage 3 cases, and one Stage 4 case. The mean tumor size was 5.0 cm, and portal invasion was suggested in 8 cases by angiography. The tumors were divided into 5 types: 13 cases of the single nodular type (SN), 7 cases of the single nodular type with proliferation (SN-P), 3 cases of the multinodular fused type (MN-F), 5 cases of the multinodular type (MN), and 4 cases of the massive type. A complication of liver dysfunction was detected in 14 cases, and half of them were Childs class C. In all, 7 patients underwent hepatectomy and 6 received percutaneous ethanol injection after TAPCE. The treated area of TAPCE was classified as segmental, lobar, or total. Segmental and lobar administration of TAPCE yielded statistically effective results, and their tumor response rate was 86%. All of the MN-F and massive types showed a good tumor response. The incidence of intrahepatic distant metastasis was higher in the localized TAPCE group than in the total TAPCE group. Segmental and lobar TAPCE should be applied for localized infiltrating HCCs, even in cases associated with liver cirrhosis, but these methods have a limited capacity to prevent distant intrahepatic metastasis.By administering an excessive amount of iodized oil via the hepatic artery, anticancer drugs in the iodized oil flow into the portal vein through the arterioportal communication. This phenomenon permits chemotherapy against extracapsular infiltration by a hepatocellular carcinoma (HCC) nourished by the portal blood flow. From May 1983 through July 1992, 240 cases of HCC underwent transcatheter arterioportal chemoembolization (TAPCE) with more than 5 ml of iodized oil (mean, 15 ml) in our hospital. In all, 32 patients survived for more than 3 years, and the factors favoring the efficacy of TAPCE therapy were investigated. Doxorubicin (mean, 46 mg) was given to 31 patients and 20 mg mitomycin C was given to 1 patient. The patients included one Stage 1 case, 13 Stage 2 cases, 17 Stage 3 cases, and one Stage 4 case. The mean tumor size was 5.0 cm, and portal invasion was suggested in 8 cases by angiography. The tumors were divided into 5 types: 13 cases of the single nodular type (SN), 7 cases of the single nodular type with proliferation (SN-P), 3 cases of the multinodular fused type (MN-F), 5 cases of the multinodular type (MN), and 4 cases of the massive type. A complication of liver dysfunction was detected in 14 cases, and half of them were Childs class C. In all, 7 patients underwent hepatectomy and 6 received percutaneous ethanol injection after TAPCE. The treated area of TAPCE was classified as segmental, lobar, or total. Segmental and lobar administration of TAPCE yielded statistically effective results, and their tumor response rate was 86%. All of the MN-F and massive types showed a good tumor response. The incidence of intrahepatic distant metastasis was higher in the localized TAPCE group than in the total TAPCE group. Segmental and lobar TAPCE should be applied for localized infiltrating HCCs, even in cases associated with liver cirrhosis, but these methods have a limited capacity to prevent distant intrahepatic metastasis.

Low-Temperature Magnetic Orderings and Fermi Surface Properties of LaCd11, CeCd11, and PrCd11 with a Caged Crystal Structure

We succeeded in growing single crystals of cage-structure compounds RCd11 (R: La, Ce, and Pr) and precisely studied their low-temperature magnetic and electronic properties by measuring electrical resistivity, magnetic susceptibility, magnetization, specific heat, and the de Haas–van Alphen (dHvA) effect. We found antiferromagnetic ordering at 0.44 and 0.39 K in CeCd11 and PrCd11, respectively, and clarified the magnetic phase diagrams of the compounds. In addition, low-lying crystalline electric field (CEF) schemes were proposed from the specific heat results of both compounds. From the present study, the antiferromagnetic ordering in PrCd11 is found to be of the exchange-induced type with a singlet ground state. From the dHvA experiment, we detected small dHvA branches ranging from 7 � 10 5 to 2 � 10 7 Oe, which correspond to small Fermi surfaces. This is mainly due to a small Brillouin zone based on a large unit cell. Moreover, the dHvA frequencies and cyclotron masses are approximately the same among RCd11, revealing a localized character of 4f electrons in CeCd11 and PrCd11.