笹沼 英紀

PURPOSE: Acoustic radiation force impulse (ARFI) is a modality for elasticity imaging of various organs using shear waves. In some situations, the heart is a candidate for elasticity evaluation with ARFI. Additionally, an ultrasound contrast agent (UCA) provides information on the blood flow conditions of the cardiac muscle. This study aimed to evaluate ARFI's effect on the heart concomitantly with UCA administration (i.e., perfluorobutane). METHODS: Ultrasound with ARFI was applied to the hearts of male Japanese white rabbits (n = 3) using a single-element focused transducer with or without UCA administration. They were exposed to ultrasound for 0.3 ms with a mechanical index (MI) of 1.8. UCA was administered in two ways: a single (bolus) injection or drip infusion. Electrocardiograms were recorded to identify arrhythmias during ultrasound exposure. RESULTS: Extrasystolic waves were observed following ultrasound exposure with drip infusion of UCA. Life-threatening arrhythmia was not observed. The frequency of the extra waves ranged from 4.2 to 59.6 %. With bolus infusion, extra waves were not observed. CONCLUSIONS: Arrhythmogenicity was observed during ultrasound (MI 1.8) with ARFI and concomitant administration of UCA in rabbits. Although the bolus administration of UCA was similar to its clinical use, which may not cause extra cardiac excitation, cardiac ultrasound examinations with ARFI should be carefully performed, particularly with concomitant use of UCA.

PURPOSE: Acoustic radiation force impulse (ARFI) has recently been used for tissue elasticity measurement and imaging. On the other hand, it is predicted that a rise in temperature occurs. In-situ measurement of temperature rise in animal experiments is important, yet measurement using thermocouples has some problems such as position mismatch of the temperature measuring junction of the thermocouple and the focal point of ultrasound. Therefore, an in-situ measurement system for solving the above problems was developed in this study. METHODS: The developed system is composed mainly of an ultrasound irradiation unit including a custom-made focused transducer with a through hole for inserting a thin-wire thermocouple, and a temperature measurement unit including the thermocouple. RESULTS: The feasibility of the developed system was evaluated by means of experiments using a tissue-mimicking material (TMM), a TMM containing a bone model or a chicken bone, and an extracted porcine liver. The similarity between the experimental results and the results of simulation using a finite element method (FEM) implied the reasonableness of in-situ temperature rise measured by the developed system. CONCLUSION: The developed system will become a useful tool for measuring in-situ temperature rise in animal experiments and obtaining findings with respect to the relationship between ultrasound irradiation conditions and in-situ temperature rise.

PURPOSE: Acoustic radiation force (ARF) impulse can be used to estimate the elasticity of cardiac muscle. The purpose of this study was to evaluate the effect of ARF on the heart with concomitant administration of the ultrasound contrast agent (UCA) perfluorobutane for recently developed elasticity imaging such as shear wave imaging. METHODS: Ultrasound with ARF was applied to the heart of Japanese white rabbit with or without UCA administration. During the exposure, electrocardiographs were recorded. RESULTS: Following the exposure of ultrasound with a duration of 10 ms and a mechanical index (MI) of 4.0 to the heart, extra waves (QRS complex) were observed only after UCA administration. Although life-threatening arrhythmia was not observed, a greater increase in the frequency of the extra waves was observed following a drip infusion compared with a single (bolus) UCA infusion. In addition, 16.3 % of extra waves were followed by arterial pressure pulse. CONCLUSIONS: Cardiac ultrasound with higher MI and longer duration should be carefully considered, particularly with the concomitant use of UCA and higher MI.

BACKGROUND: Sorafenib is a multikinase inhibitor with antiangiogenic and antiproliferative properties, approved for the treatment of hepatocellular carcinoma. The effect of Sorafenib on liver regeneration in healthy rats was investigated. METHODS: Sixty Wistar rats received either Sorafenib (group S; 15 mg/kg) or placebo for 14 days prior to resection and until sacrifice. After a 70% partial hepatectomy, the rats were euthanized on post-operative days (POD) 2, 4 or 8. Hepatocyte proliferation was estimated by immunohistochemistry for Ki-67 antigen using stereological methods on sections prepared by systematic uniform random sampling. RESULTS: Seven animals (12%) died after surgery. Death rates were similar in treated rats and controls. At hepatectomy, the body weight was significantly lower in group S rats. The liver weight and regeneration rates were lower in group S rats on PODs 2, 4 and 8. Hepatocyte proliferation was significantly lower in group S animals on PODs 2 and 4. Alanine aminotransferase ALAT was significantly higher in the Sorafenib-treated group on PODs 2, 4 and 8. Alkaline phosphatase ALP and bilirubin levels were similar in the two groups, although bilirubin was elevated in group S rats on POD 8. CONCLUSION: In this rat model, Sorafenib did not increase post-hepatectomy mortality, but was associated with a significant impaired liver weight gain, regeneration rates and hepatocyte proliferation.

BACKGROUND: Rodent models have been used to evaluate aspects of liver regeneration. The aim of the present study was to investigate the natural history of liver regeneration in healthy rats. METHODS: A 70% partial hepatectomy was performed in 64 rats. The animals were randomised into 8 groups and evaluated on postoperative days one to eight. Hepatocyte proliferation was evaluated by immunohistochemistry using unbiased stereological principles. RESULTS: The mean rat body weight was 238 g (211-287). The mean weight of the resected liver was 6.3 g (5.2-7.3) and the estimated mean total liver weight was 8.9 g (7.4-10.4). Both liver weight analysis and regeneration rate showed an ascending curve, with a maximum slope on postoperative days 1-4, reaching a steady state on days 5-8. Hepatocyte proliferation (positive Ki-67 cell profiles pr. mm(2)) was high (250 cell profiles/mm(2)) on postoperative days 1-3 and tapered off on day 5. CONCLUSION: Seventy percent partial hepatectomy in healthy rats induces a rapid regenerative response and PODs 2, 4 and 8 seems optimal for assessing hepatic growth in future studies.

2001年～2011年に施行した大腿ヘルニア手術症例52例を検討した。全例でCT 施行し，大腿ヘルニアの術前診断は41例（CT 正診率80％）だった。嵌頓群は37例（71％）で，イレウス症状は20例（嵌頓群の54％）で認め，全例緊急手術を要した。ヘルニア内容は小腸27例（73％）が最も多かった。腸切除は16例（43％）で施行した。発症から手術までの経過時間は，切除群と非切除群で平均値は同等で有意差を認めなかった（P=0.621）。後壁補強は McVay 法が37例（95％）で施行され，非嵌頓群では各種メッシュ法が53％で選択されていた。術後合併症は嵌頓群で有意に多かったが，腸切除の有無では有意差を認めなかった。腸切除を避けるためには，早期診断・治療が必要であり，発症からできるだけ早いタイミングでの介入が有効と考えられた。