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  • 1
    ISSN: 1420-9098
    Keywords: Key words:Myrmica kotokui, microgyne, macrogyne, polygyny, monogyny, allometry.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary: Social structure and sexual size of two populations of Myrmica kotokui were compared. Most of the colonies were polygynous in one population and monogynous in the other. Mean body size of the queens was larger in the monogynous population than in the polygynous population. Although the polygynous population contained many large queens, their wing length was significantly shorter than that of queens in the monogynous population. Some females in the polygynous population were intermorphic between typical workers and queens, while the females of the monogynous population were clearly divided into worker and queen castes without any intermorphic females. The body size of the males showed a large variation and the mean was not significantly different between the two populations.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Keywords Ovarian hormones ; beta-cell ; hypertrophy ; pancreatectomy ; OLETF rat.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A sexual dimorphism regarding the incidence of diabetes mellitus in OLETF rat, a model of Type II diabetes, has been reported. As a result, the effects of ovarian hormones on beta cells per se was examined by comparing the capacity of beta-cell proliferation and changes in blood glucose and plasma insulin concentrations after a 70 % pancreatectomy. All female animals were randomly assigned to two protocols. The rats involved in protocol I received either a 70 % pancreatectomy (Px) or a sham pancreatectomy (sham) at 6 weeks of age, along with their diabetes-resistant counterparts, female LETO rats, which served as normal controls. The rats belonging to protocol II were given an ovariectomy (Ox) at 5 weeks of age, and one week later, they were subjected to either Px or the sham operation, with/without hormone (estradiol, 50 μg/kg; testosterone, 1 mg/kg) replacement. The findings indicate that the capacity for compensatory growth of beta cells after Px was affected by both sex hormonal and genetic components, since a 70 % Px resulted in sustained hyperglycaemia within the first week after surgery, but was ameliorated by an increase in beta-cell mass thereafter in the non-Ox Px OLETF rats. The Ox also caused a decline in beta-cell mass which could be improved by replacement with ovarian hormones. Not only endogenous but also replacement ovarian hormones, led to a beneficial effect on beta cells per se in OLETF female rats. This was reflected by an increased beta-cell mass accompanied by a parallel increase in plasma immunoreactive insulin concentration. The effects of ovarian hormones, however, contributed to the beta-cell hypertrophy rather than expansion of the beta-cell population to achieve glucose homeostasis, as evidenced by an increased area of individual beta-cell after Px rather than an increased BrdU-labelling index for the beta cells. The present study suggests that ovarian hormone-induced beta-cell hypertrophy may typically occur, to compensate for changes in functional demand as the results of a 70 % Px in female OLETF rats. [Diabetologia (1998) 41: 799–805]
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0509
    Keywords: Key words: Angiography—Arteriovenous malformation—Embolization—MRI—Vaginal tumor.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Vaginal arteriovenous malformations (AVMs), although rare, can lead to life-threatening complications. We report the first case of a vaginal AVM whose diagnosis and follow-up were performed by magnetic resonance imaging (MRI). MRI findings of the AVM are the blood flow-related features within the tumor, such as the phase-shift artifact, paradoxical enhancement, and flow voids.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Abdominal imaging 23 (1998), S. 592-599 
    ISSN: 1432-0509
    Keywords: Key words: Liver, MR—Liver neoplasms, MR—Liver neoplasms, diagnosis—Magnetic resonance (MR), contrast enhancement—Bile ducts, neoplasms.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Background: To determine the spectrum of appearances of gadolinium retention within cholangiocarcinoma (CCA) and other liver neoplasms. Methods: Two hundred ten patients underwent hepatic magnetic resonance imaging (MRI) at 1.5 T with precontrast T1- and T2-weighted spin-echo (SE) images and delayed Gd-DTPA- or gadoteridol- (0.1 mmol/kg) enhanced T1-weighted SE images. Postcontrast images were evaluated for lesions suspicious for tumors, and lesion signal intensity was characterized as homogeneously or heterogeneously hypo-, iso-, mildly hyper-, or markedly hyperintense to liver. Data from 94 patients with benign or malignant neoplasms are presented. Results: Imaging demonstrated 237 malignant neoplasms (121 hepatocellular carcinoma [HCC], 26 CCA, 17 colon carcinoma metastases, 73 other tumors) and 28 benign neoplasms (22 hemangioma, six focal nodular hyperplasia [FNH]). One hundred forty malignant lesions appeared as homogeneous postcontrast (29 hypointense, 75 isointense, 17 mildly hyperintense, 19 markedly hyperintense) and 97 as heterogeneous (15 isointense, 50 mildly hyperintense, 32 markedly hyperintense). Malignant lesions showing homogeneous, mildly or markedly hyperintense signal intensity postcontrast included 10 CCA, seven HCC, six epithelioid hemangioendothelioma, eight neuroendocrine tumor metastases, three adenocarcinoma metastases of unknown origin, and one breast carcinoma metastasis. Hemangiomas appeared as homogeneous postcontrast in 19 lesions (six isointense, one mildly hyperintense, 12 markedly hyperintense) and as heterogeneous in three lesions (markedly hyperintense). FNH appeared as homogeneous postcontrast in one lesion (isointense) and as heterogeneous in five lesions (one isointense, four mildly hyperintense). Conclusion: Homogeneous gadolinium retention on delayed postcontrast images of malignant hepatic neoplasms is seen in a high percentage of CCA lesions and less commonly with other neoplasms.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0509
    Keywords: Key words: Liver, neoplasms—Liver, ultrasound—Liver, computed tomography—Liver, magnetic resonance—Comparative studies.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Purpose: The purpose of this study was to assess the imaging findings of pathologically-proved small hepatic nodules 2 cm in size or smaller detected with ultrasonography in cirrhotic patients with suspected hepatocellular carcinoma (HCC). Materials and Methods: We evaluated sonographically detected 32 small hepatic nodules which were pathologically confirmed in 23 consecutive cirrhotic patients who were suspected of having HCC. Twenty-six lesions were confirmed with ultrasonographically-guided aspiration needle-core biopsy, and six with definitive surgery. Ultrasonographic examination records were retrospectively reviewed. CT, and MR images obtained with various imaging techniques were retrospectively reviewed by two radiologists in a blind fashion. Results: The 32 hepatic nodules were comprised of seven focal fatty changes, two large regenerative nodules, three low-grade dysplastic nodules, five high-grade dysplastic nodules, and fifteen HCCs. Ultrasonography showed various echogenicity for the hepatic nodules. The signal-intensity characteristics with T1-weighted spin-echo, in-phase gradient-recalled-echo, and dynamic MR imagings may be useful in distinguishing HCC from nonHCC nodules. Conclusions: Nearly half of small hepatic nodules detected with ultrasonography were nonHCC nodules. Ultrasonographic findings may not be reliable in characterizing small hepatic nodules in cirrhosis. CT and MR imaging obtained with the various techniques are still insensitive to these hepatic nodules. RID=""ID=""〈e5〉Correspondence to:〈/e5〉 M. Kanematsu
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0509
    Keywords: Key words: Liver, neoplasms—Computed tomography (CT)—Contrast media—Helical.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: To determine the optimal phases of dynamic computed tomography (CT) for detecting hepatocellular carcinoma (HCC). Methods: Fifty-two patients with 85 HCC nodules were examined by means of unenhanced and triple-phase CT images of the whole liver. The time for obtaining the arterial-phase images was 25–55 s after intravenous bolus injection of contrast material, the time for obtaining the portal venous-phase images was 65–100 s, and the time for obtaining late-phase images was 145 s to 4 min. Detectability of the HCC nodules for all phases was statistically compared. Results: The detection rates for the arterial- and late-phase images were significantly higher than for the unenhanced and portal venous-phase images (p 〈 0.01). The combination of arterial- and late-phase images showed the same number of HCC nodules in the same number of patients as did the combination of unenhanced and triple-phase images. Conclusion: The combination of the arterial- and late-phase imagings was best for detecting HCC nodules.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Abdominal imaging 22 (1997), S. 35 -40 
    ISSN: 1432-0509
    Keywords: Key words: Stomach—Gastric cancer—Magnetic resonance imaging—Dynamic study, contrast media
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Dynamic magnetic resonance (MR) images in 37 patients with gastric cancers were obtained by a two-dimensional fast multiplanar spoiled gradient technique. The degree of tumor invasion was classified into four grades regarding a low-intensity band between the stomach and surrounding fat. Advanced gastric cancer was strongly enhanced, appearing as a thickened wall, by the contrast medium during the early to delayed phases of dynamic studies. The extent of invasion of the adjacent organs was diagnosed by the difference in enhancement between the tumor and the parenchyma. The sensitivity of extraserosal invasion was 93%. Dynamic MR diagnosis is useful for evaluating the extent of gastric carcinoma.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0509
    Keywords: Key words: Uterus, cervix, neoplasm—Magnetic resonance, diagnosis. [xm [fs99]
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Background: To identify the reasons for misdiagnosis of the degree of stromal invasion by uterine cervical cancer with various magnetic resonance sequences. Methods: T2-weighted, dynamic, and postcontrast T1-weighted images were obtained in the sagittal plane in 20 patients with uterine cervical cancer. After evaluating these sequences for the degree of stromal invasion, histologic specimens were directly correlated with these images. Results: The degree of stromal invasion was correctly diagnosed in 15 of the 20 cases on T2-weighted images, in 12 on dynamic images, and in eight on postcontrast T1-weighted images. All misdiagnoses were due to overestimation. Histologically, peritumoral stroma showed inflammation or edema in two patients, whereas no histological abnormality was found in the other patients. A hyperintense rim, i.e., a peritumoral enhanced ring-shaped structure, was observed on the enhanced images of five patients. The hyperintense rim corresponded to the periphery of the tumor in three patients and to the cervical stroma in two patients. Conclusion: T2-weighted images permitted the most accurate evaluation of stromal invasion by uterine tumors. Overdiagnosis may be due to an abnormal intensity of the cervical stroma, which was observed more frequently on dynamic and postcontrast T1-weighted images than on T2-weighted images.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0509
    Keywords: Key words: Pancreas—calcification—Neoplasms—Adenocarcinoma—Computed tomography (CT)—Helical.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We present two cases of ductal adenocarcinoma of the pancreas with intratumoral calcification. The two cases indicate two different etiologies for intratumoral calcification in ductal adenocarcinoma. Thus, the possibility of adenocarcinoma should be considered when a tumor with intratumoral calcification is found, although the incidence of intratumoral calcification in the ductal adenocarcinoma of the pancreas remains rare.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0509
    Keywords: Mixed hepatocellular and cholangiocellular, carcinoma ; MR imaging ; Dynamic MR imaging-Histopathologic study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two patients with mixed hepatocellular and cholangiocellular carcinoma underwent partial hepatectomy after magnetic resonance (MR) imaging. Correlation is made with the histopathologic manifestations. In both cases the tumors showed relative low signal intensities on T1-weighted spin-echo (SE) images and high signal intensities on T2-weighted SE images. Dynamic MR imaging showed the enhancement from the periphery of the tumor to the inner area gradually and the enhancement continued into the delayed phase. With both cases fibrosis was marked in the inner area of the tumor compared to the peripheral area. The extent and degree of fibrotic tissue is considered to reflect the enhancement on dynamic MR imaging.
    Type of Medium: Electronic Resource
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