Evaluation of renal function by dynamic MR imaging: effect of water load.

The aim of this study was to investigate the usefulness of magnetic resonance (MR) imaging in the evaluation of renal function, with particular attention to the effects of water load. Ten healthy volunteers underwent dynamic MR imaging after an injection of gadolinium diethylene-triaminepenta-acetic acid (Gd-DTPA) as a contrast agent to evaluate renal function by the following four methods: the positive method [longitudinal relaxation time (T1) shortening is the dominant effect], the negative method [transverse relaxation time (T2) shortening is the dominant effect] and two intermediate methods by switching the Gd-DTPA concentrations used in the positive and negative methods. A prolonged cortical peak time and a reduced medullary peak level were observed by the positive method under a dehydrated condition, suggesting that these variables were slightly influenced by Gd-DTPA concentrated in the medulla. By the negative method, low signals due to T2* (T2* is the effective transverse relaxation time, typically shorter than T2) shortening appeared in the medulla under normal conditions, but these signals were unclear when the subject was under an overhydrated condition. These results indicate that water metabolism, in addition to imaging parameters and Gd-DTPA dose levels, should be considered when renal function is evaluated by dynamic MR imaging. Analysis of both the pattern of MR images and the time-signal intensity curves may be useful in the evaluation of renal function. The results also indicate that the positive method is preferred when the patient is overhydrated as it allows the evaluation of the local renal kinetic function by recording changes in the regional contrast agent levels.</p

Hepatic infarction following abdominal interventional procedures.

To clarify the incidence, background, and progress of hepatic infarction following interventional procedures, cases of hepatic infarction following interventional procedures at our department during the last decade were identified by reviewing the clinical records of 1982 abdominal angiography and interventional procedures and records of abdominal CT. Nine episodes (0.5%) in 8 patients were identified as hepatic infarction following an interventional procedure. Five episodes were preceded by embolization of the hepatic or celiac artery at emergency angiography for postoperative bleeding with hemorrhagic shock. Three episodes followed the elected interventional procedure for hepatocellular carcinoma, and the remaining episode occurred after 12 months of chemoinfusion through an indwelling catheter in the hepatic artery and portal vein. Hepatic arterial occlusion in all episodes and portal venous flow abnormality in 5 episodes were observed on angiography. Four patients whose liver function was initially impaired died of hepatic infarction, although the extent of the disease on CT did not appear to be related to the mortality. Multiple risk factors, including arterial insufficiency, were observed in each patient. The incidence of hepatic infarction following interventional procedures in this series was low but sometimes fatal, and occurred most frequently in emergency embolization in hemorrhagic shock.</p

Differential diagnosis of adrenal masses by chemical shift and dynamic gadolinium enhanced MR imaging.

Chemical shift MRI is widely used for identifying adenomas, but it is not a perfect method. We determined whether combined dynamic MRI methods can lead to improved diagnostic accuracy. Fifty-seven adrenal masses were examined by chemical shift and dynamic MR imaging using 2 MR systems. The masses included 38 adenomas and 19 non-adenomas. In chemical shift MRI studies, the signal intensity index (SI) was calculated, and the lesions classified into 5 types in the dynamic MRI studies. Of the 38 adenomas studied, 37 had an SI greater than 0. In the dynamic MRI, 34 of 38 adenomas showed a benign pattern (type 1). If the SI for the adenomas in the chemical shift MRI was considered to be greater than 0, the positive predictive value was 0.9, and the negative predictive value was 0.94 and kappa = 0.79. If type 1 was considered to indicate adenomas in the dynamic MRI, the corresponding values were 0.94, 0.81 and kappa = 0.77 respectively. The results obtained when the 2 methods were combined were 1, 0.95 and kappa = 0.96 respectively. The chemical shift MRI was found to be useful for identifying adenomas in most cases. If the adrenal mass had a low SI (0 &#60; SI &#60; 5), dynamic MRI was also found to be helpful for making a differential diagnosis.</p

放射線エネルギーの違いによる喉頭癌における吸収線量の影響

We investigated the usefulness of Gafchromic MD-55 film (Nuclear Associates, Inc.) for measuring the radiation doses on the radiotherapy of laryngeal cancers. Since larynx has thin wedge-shaped structure in anterior neck adjacent to airway, the radiation doses to the lesion may be diminished because of build-up and build-down. So, the dose has been measured with conventional measuring systems such as thermoluminescent dosimetry (TLD). However, it was not possible to evaluate the dose distribution correctly using TLD, because it is impossible to float a TLD chip in an air cavity. In this study, we employed Gafchromic MD-55 film as a dosimeter, for it can be set on the area of interest and with a measurability of dose range of 3 to 100 Gy, though it has no energy dependency. And this radiometer is composition near the soft tissue of the human body. The dose distributions to larynx were investigated with this film using neck phantom under each radiation beam energy of 4, 6 and 10 MV x-rays. Our neck phantom is made from acrylic resin and simulates a normal larynx on the basis of image information of computed tomography (CT). Moreover we observed secondary build-up and build-down curves in tissue in the vicinity of air cavities, especially at 10 MV x-rays. These findings suggest that patients with TI-T2 glottic cancers with anterior commissure invasion may receive more effective treatment with 4 MV x-rays rather than with 6 MV and 10 MV x-rays.Tl声門癌に対して放射線治療を単独で行うのは確立している方法である｡しかし,頚部は解剖学的に複雑であり,前方に薄いⅤ字形で,喉頭が気道に隣接している構造を持つので,病巣への線量はbuild-upとbuild-downの影響による線量低下が生じることが考えられる｡すなわち,放射線エネルギーの選択が喉頭癌の局所的制御に影響を及ぼすと言える｡この影響は,より高い放射線エネルギーでは,それに伴いより強く起きるということが基礎実験にて報告されている｡また,それらの線量測定は,熱ルミネセンス線量計(TLD)のような従来の測定システムで測定されていた｡しかし,空気空洞へTLD を単体 で浮かせ線量を正確に測定し評価を行うのは困難である｡本研究において,我々は Gafchromic MD-55 film (Nuclear Associates, Inc.)を使用し測定した｡ Gafchromic MD-55 film は,フィルムタイプ線量計でありエネルギー依存性がなく,3～100 Gyを測定可能であり,アクリル製頸部ファントムの空気組織境界面及び,空洞部に線量計を容易に精度良く配置することが可能である｡また,この線量計は人体の軟部組織に近い組成である｡そこで, 4, 6および10MVの各エネルギーでこの線量計を用いてエネルギーの違いによる,頸部ファントムを用いて喉頭の線量評価を行った｡その結果,我々は,特に放射線エネルギー10MVで頸部ファントムにおける,前部組織-組織空洞境界面-空洞部の一連したbuild-upおよびbuild-downを線量計で評価することができた｡これらの研究の結果､前交連浸潤を有するT1-T2に相当する声門癌患者は,放射線エネルギー6MVおよび10MVではなく,4MVを用いることによって,より効果的な放射線治療を行えると推測できる

Multivariate analysis of magnetic resonance imaging of focal hepatic lesions.

A total of 124 lesions from 1 to 6cm in diameter, including 31 cavernous hemangiomas, 32 metastases and 61 hepatocellular carcinomas (HCC) were analyzed to study the usefulness of magnetic resonance imaging (MRI) at 0.5 Tesla to differentiate focal hepatic lesions on the basis of qualitative criteria. Each focal hepatic lesion was assessed for shape, internal architecture and signal intensity relative to normal liver parenchyma. While all cavernous hemangiomas and metastases except one lesion could be detected, detection rate of HCC was significantly inferior to that of the other two diseases. A tumor capsule and a hyperintense focus on T1-weighted images were demonstrated in only HCC lesions in strong contrast with the other two diseases; however, metastases with slow-growing characteristics or subacute hematoma may appear as similar images. Cavernous hemangiomas appeared markedly hyperintense on T2-weighted images in 23 of 31 lesions, but one metastasis and one HCC had similar images. A multivariate analysis of several MRI resulted in the following mean discriminant scores: cavernous hemangioma, -1.2652; metastasis, 0.1830; and HCC, 0.7138. It appeared to be possible to differentiate the three diseases with 84.4 percent accuracy.</p

Quantitative measurement of portal blood flow by magnetic resonance phase contrast: comparative study of flow phantom and Doppler ultrasound in vivo.

A non-invasive method for measuring portal blood flow by magnetic resonance (MR) phase contrast was evaluated in a flow phantom and 20 healthy volunteers. In a flow phantom study, the flow volumes and mean flow velocities measured by MR phase contrast showed close correlations with those measured by electromagnetic flowmetry. In 20 healthy volunteers, the cross-sectional areas, flow volumes and mean flow velocities measured by MR phase contrast correlated well with those measured by the Doppler ultrasound method. Portal blood flow averaged during the imaging time could be measured under natural breathing conditions by using a large number of acquisitions without the limitations imposed on the Doppler ultrasound method. MR phase contrast is considered to be useful for the non-invasive measurement of portal blood flow.</p

Measurement of intracellular pH by flow cytometry using pH sensitive fluorescence dye, and influence of hyperthermia and amiloride derivatives on the intracellular pH

エールリッヒ腹水癌細胞とそのアドリアマイシン耐性細胞において蛍光pH指示薬2'、7'-bis-(2-carboxyethyl) carboxyfluorescein] (BCECF) の蛍光量をフローサイトメトリーで測定することによって細胞内pHの検量曲線を作成することができた。このことより、これらの細胞においてBCECFの蛍光量で細胞内pHの変化を簡易に比較できることを示唆した。さらに、温熱、Na(+)/H(+) exchanger の阻害例であるアミロライド[3,5-diamino-6-chloro-N-(diaminomethylene) pyrazinecarboxamide]、およびアミロライド誘導隊MH-12-43[N-amidino-3-amino-6-chloro-5-(N-ethyliso-propylamino) pyrazinecarboxyamide] の細胞内pHへの影響をエールリッヒ腹水癌細胞で観察した。37℃では、0.5mMアミロライド、0.05mM　MH-12-43により細胞内pHは減少し、42℃処理によりさらに減少した。42℃において、0.05mM　MH-12-43による細胞内pHの減少は、0.5mMアミロライドによる減少より大きかった。We examined relationship between intensity of intracellular fluorescence of [2', 7'-bis-(2'-carboxyethyl) carboxyfluorescein] (BCECF) and intracellular pH in Ehrlich ascites tumor cells and their adriamycin-resistant strain, and found a good correlation between them at both strains. This suggests that changes in the intracellular pH on these strains may be obtained through measurement of intracellular fluorescence of BCECF by flow cytometry. Further, we examined influence of hyperthermia, 3, 5-diamino-6-chloro-N-(diaminomethylene)pyrazinecarboxamide (amiloride), an inhibitor of Na(+)/H(+) exchanger, and its derivative; N-amidino-3-amino-6-chloro-5-(N-ethylisopropylamino) pyrazinecarboxyamide (MH-12-43) on the intracellular pH in Ehrlich ascites tumor cells. The treatment of 0.5mM amiloride or 0.05mM MH-12-43 reduced intracellular pH at 37℃, while the more reduction was observed by the treatment at 42℃. The reduction of intracellular pH by 0.05mM MH-12-43 was more substantial than that of 0.5mM amiloride at 42℃

Cepharanthin Reduces Thermotolerance by Enhancing Thermosensitivity in NIH3T3 Cells

The effects of cepharanthin (Ce), glycyrrhizin (G), verapamil (V), and G plus V on induced thermotolerance in NIH3T3 cells were studied. Cells were heated with or without the drug at 45 degrees C for 20 min (the first heating), incubated at 37 degrees C for 12h (the incubation period), and heated again at 45 degrees C for 0-210 min (the second heating). G and V were added throughout the experiment, while Ce was added throughout the experiment or during only the first or second heating, or the incubation period. The cells were harvested after the second heating to evaluate cell survival. In control experiments without any drug, thermotolerance developed and reached the highest peak in the cells incubated for 12h at 37 degrees C. However, thermotolerance in the control cells was suppressed by incubating them at 0 degree C, but developed by subsequent incubation at 37 degrees C. This suggests that the acquisition of thermotolerance by the cells required metabolic processes during the incubation at 37 degrees C. When each drug was present throughout the experiment, only Ce or the combined use of G and V was effective in reducing thermotolerance. Thermotolerance was also suppressed in the presence of Ce during the second heating. These results indicate that Ce reduces thermotolerance by enhancing thermosensitivity rather than by inhibiting the development of thermotolerance.</p

Studies of an aspect of renal function with the aid of dynamic CT and renogram.

Dynamic CT scans were conducted on 94 persons who had been randomly selected among the patients and the volunteers. The test results were used to obtain the time-density curve. A part of the subjects (20 cases) underwent the renogram examination for the comparative studies. The cortico-aortic (CA) ratio derived from the time-density curve demonstrated good correlation between the dynamic CT and the renal function (r = 0.68). When the dynamic CT studies and the renogram were compared, the vascular phase of the renogram showed strong correlation with CA ratio. Consequently the dynamic CT study the CA ratio was believed to demonstrate the renal function.</p

Modified inverse square sensitometry for the determination of the characteristic curve of radiographic screen/film systems.

To determine the characteristic curve of the radiographic screen/film systems in a short focal spot-film distance, the inverse square sensitometric method was modified by changing the radiation intensity with two kinds of filters. The characteristic curves obtained in the two exposure series with these two kinds of filters were overlapped to obtain a complete one. The characteristic curve thus obtained was almost the same as the one obtained by the original inverse square sensitometric method. The accuracy of the characteristic curves obtained by the modified method was well-reflected in the clinical radiographs.</p