[Benign neuroendocrine and other rare benign tumors of the pancreas]. / Benigne neuroendokrine und andere seltene benigne Tumoren des Pankreas.

Neuroendocrine tumors (NET) of the pancreas are rare neoplasms, which arise from cells of the islets of Langerhans. The most common NET are the insulinoma, gastrinoma and hormone inactive NET. Very rare entities are the schwannoma, leiomyoma, teratoma, intrapancreatic lipoma, hemangioma and the intrapancreatic accessory spleen. Essential for therapy, which in most cases is difficult, are an exact localization and various modalities of imaging diagnostics.

[Virtual multislice computed tomography cystoscopy for evaluation of urinary bladder lesions]. / Virtuelle MDCT-Zystoskopie bei der Detektion von Blasenläsionen.

The introduction of multislice computed tomography (MDCT) with the possibility of acquiring isotropic datasets has been an ideal prerequisite for development of virtual MDCT cystoscopy. Remarkable technical progress regarding post-processing of high-resolution 3D datasets as well as a considerable reduction of the time required for post-processing made it possible to introduce virtual MDCT cystoscopy into the clinical routine. 3D post-processing that often required 7-8 h when virtual endoscopy techniques were first developed can now be performed in less than 5 min after transfer of data to the 3D workstation. With the limitations and contraindications of conventional cystoscopy in mind, virtual MDCT cystoscopy may be seen as a valuable alternative to conventional cystoscopy for evaluation of hematuria.

[Percutaneous liver biopsy. Overview of different techniques]. / Perkutane Leberbiopsie. Ubersicht über verschiedene Verfahren.

To classify a liver tumor, image-guided percutaneous biopsy of a liver lesion is indicated. Using ultrasound (US) to guide a biopsy needle into a liver lesion has been proven useful and safe. If a lesion cannot be seen on US or the access to a lesion has been complicated by its position, CT-guided biopsy can be performed. If a lesion cannot be delineated on US or CT, MR-guided biopsy is recommended. Using hepatospecific contrast agents, the time span to delineate tumor tissue can be prolonged. To differentiate diffuse liver disease, transvenous biopsy under fluoroscopic control can be performed if a percutaneous biopsy is contraindicated. In recent years fine-needle aspiration biopsy has been increasingly replaced by coaxial 14-20 G core biopsy, which is a safe and efficient technique to classify liver lesions and has a low complication rate.

[MRT of the liver. Clinical significance of nonspecific and liver-specific MRT contrast agents]. / MRT der Leber. Klinische Bedeutung nichtspezifischer und leberspezifischer MRT-Kontrastmittel.

The liver is a common site for various benign and malignant focal lesions. The initial modality for assessing liver lesions is ultrasound or CT. MRI with its superior soft tissue contrast offers multiple advantages over other imaging modalities. Contrast agents have been developed that increase the detection rate and provide more specific information in comparison to unenhanced techniques. In the mean time three classes are available for MR imaging of the liver: extracellular gadolinium chelates, hepatobiliary and reticulo-endothelia, superparamagnetic agents. We describe in this review the most common focal lesions, their diagnostic possibilities, and the imaging protocols. Clinical use of these contrast agents facilitates detection and differential diagnosis of focal liver lesions that may help to avoid invasive procedures such as biopsy for lesion characterization.

[MRI of the ankle joint. Comparison of the 1.0-T and the 0.2-T units]. / MRT des Sprunggelenks. Vergleich eines Ganzkörper-Mittelfeldgeräts (1.0 T) mit einem dedizierten Niederfeldgerät (0.2 T).

PURPOSE: Comparison of ankle joint injuries with different MR systems and at different field strengths. METHOD: Ten patients with acute ankle injuries were examined using mid-field (1.0 T) and dedicated low-field (0.2 T) MR units. Findings of ligamentous injury, sinus tarsi involvement, bone injury, and tendon injury were correlated. RESULTS: There was no significant difference between mid- and low-field MR imaging for ligamentous injuries (chi 2 = 0.0395), sinus tarsi changes bone injuries (chi 2 = 0.0507; critical value = 5,991). CONCLUSION: This study showed good agreement in pathological findings in ankle injury on mid-field and low-field MR imaging.

[Comparison of diagnostic sensitivity in meniscus diagnosis of MRI examinations with a 0.2 T low-field and a 1.5 T high field system]. / Vergleich der diagnostischen Sicherheit in der Meniskusdiagnostik von MRT-Untersuchungen an einem 0.2-T-Niederfeld- und 1.5-T-Hochfeldsystem.

The aim of this study was to evaluate the reliability of a low field strength MRI unit (0.2 T; Esaote, Biomedica) and a high field strength MRI unit (1.5 T; Siemens) in detecting meniscal lesions. Twenty patients were investigated on a 0.2-T low-field MRI unit and a 1.5-T high-field MRI unit for meniscal lesions. Evaluation was performed of four meniscal compartments (anterior and posterior medial and lateral meniscus), for a total of 80 observations. The reliability of diagnosis was ranked qualitatively on a three-point scale. Investigations of the high-field MRI unit revealed a meniscal tear in 6 patients and ruled out a tear in 14 patients. Evaluation of individual meniscal compartments revealed diagnosis with high confidence in 58 observations and with moderate confidence in 22 observations. Investigations of the low-field MRI unit revealed a meniscal tear in 5 patients and ruled out tears in 15 patients. Evaluation of individual meniscal compartments revealed diagnosis with high confidence in 39 observations, with moderate confidence in 38 observations, and with low confidence in 3 observations. The diagnosis in high- and low-field images was identical in 98.7% of cases; in one patient observations from the high-field unit changed the therapeutic management. Diagnostic reliability was significantly higher with high-field strength MR imaging. Low field strength MR imaging shows comparatively high diagnostic accuracy for meniscal lesions compared to high field strength imaging; however, we demonstrated a significantly higher confidence in diagnosis with high-field MR imaging.

[MRI in radiologically occult scaphoid fractures. Initial experiences with 1.0 Tesla (whole body-middle field equipment) versus 0.2 Tesla (dedicated low-field equipment)]. / MRT bei radiologisch okkulten Kahnbeinfrakturen. Erste Erfahrungen von 1.0 Tesla (Ganzkörper-Mittelfeldgerät) versus 0.2 Tesla (dediziertes Niederfeldgerät).

The study was performed to determine the diagnostic value of different MR systems and field strengths in patients with occult scaphoid and wrist fractures. Twelve patients with clinical suspicion of a scaphoid fracture but normal plain radiographs were examined by MRI. A dedicated 0.2-T unit (Esaote) and a 1.0-T unit (NT10, Philips) were used. Coronal T1W-SE, STIR, and T2*W-GE sequences were obtained with both systems. Images were evaluated for a bone marrow abnormality, a trabecular or cortical fracture line, and were compared to the 6-week follow-up radiographs. Seven wrist fractures were found at 0.2 T and 1.0 T, proven in the follow-up radiographs. A bone marrow abnormality was present in all seven fractures on both systems. Trabecular and cortical fracture lines were visualized at 0.2 T in four cases and at 1.0 T in seven cases. Low-field MR imaging at 0.2 T and mid-field MR imaging at 1.0 T seem to be equivalent in the diagnosis of a fracture in radiographically occult scaphoid and wrist fractures. In the visualization of fracture details, important for therapeutic and prognostic considerations, 1.0 T seems to be superior.

Schwann cells express NDF and SMDF/n-ARIA mRNAs, secrete neuregulin, and show constitutive activation of erbB3 receptors: evidence for a neuregulin autocrine loop.

Cultured Schwann cells secreted low levels (30 pg/ml/1.5 x 10(6) cells) of a 45-kDa neuregulin protein and showed constitutive activation of a neuregulin receptor, Erb-B3, suggesting the existence of an autocrine loop involving neuregulins in Schwann cells. RT-PCR analyses indicated that Schwann cells and fibroblasts in culture produced SMDF/n-ARIA and NDF but not GGF neuregulin messages. Schwann cell and fibroblast neuregulin messages encoded both beta and alpha domains; Schwann cell transcripts encoded only transmembrane neuregulin forms while fibroblast messages encoded transmembrane and secreted forms. SMDF/n-ARIA and NDF messages were also expressed in early postnatal rat sciatic nerve, suggesting a role for neuregulins in peripheral nerve development. An anti-neuregulin antibody inhibited the mitogenic response of Schwann cells to cultured neurons and to extracts of cultured neurons or embryonic brain, consistent with the accepted paracrine role of neuregulins on Schwann cells. Surprisingly, the same antibody inhibited Schwann cell proliferation stimulated by several unrelated mitogens including bFGF, HGF, and TGF-beta1. These data implicate both paracrine and autocrine pathways involving neuregulin form(s) in Schwann cell mitogenic responses.

Components of Stroop-like interference in word reading.

Previous research has shown that the naming of the picture of, for example, a guitar is substantially delayed when it is accompanied by the name of an object from the same semantic category (e.g., piano) as compared to a nonword control (e.g., xxxxx). La Heij (1988a) has shown that a large part of this Stroop-like interference effect can be attributed to two semantic characteristics of the distractor word: its semantic similarity to the target picture and its semantic relevance in the task at hand. Furthermore, it was argued that the locus of these two interference effects is the process of target-name retrieval. If this is true, semantic interference effects should diminish or disappear when, instead of a picture-naming task, a word-reading task is used. In the present study this prediction is tested. The effects of four distractor characteristics are examined: semantic relatedness, semantic relevance, response set membership and wordness. In contrast to the original picture-naming task only the effect of wordness reached significance. The results of experiments 2 and 3 show that the absence of significant semantic context effects in experiment 1 is not simply due to the fact that a distractor word has less time to affect a word-reading response. The results are taken to support a name-retrieval account of semantic interference in color and picture naming.