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Biomedical subjects

P Reimer

Publications and source records attributed to P Reimer.

At least 109 records · Page 6Linked to original sources
PubMed1992

Techniques for high-resolution echo-planar MR imaging of the pancreas.

Recent technical advances in echo-planar magnetic resonance (MR) imaging prompted an investigation of these new techniques in pancreatic MR imaging and evaluation of bowel lumen enhancement with an aqueous bowel contrast agent. In 42 subjects (36 healthy, six with pancreatic disease), various T1-weighted inversion-recovery and T2-weighted spin-echo fat-suppressed pulse sequences were assessed with an echo-planar technique implemented with a modified clinical MR imager. Single-excitation imaging (echo time, 26 msec) provided a higher (P less than .05) signal-to-noise ratio than did conventional spin-echo and all other echo-planar techniques. In 13 (72%) of 18 healthy subjects who did not undergo administration of the contrast agent, the entire pancreas was distinguished from adjoining bowel. In all 18 subjects who underwent contrast-enhanced imaging, a significantly greater (P less than .05) intraluminal signal intensity was apparent with all echo-planar pulse sequences and the entire pancreas was identified. In six patients with pancreatic disease, lesions could be identified by their difference in signal intensity.

Barium Sulfate↗
PubMed1992

Receptor-directed contrast agents for MR imaging: preclinical evaluation with affinity assays.

In this study, the target-specific behavior of magnetic resonance (MR) imaging contrast agents directed at human hepatic asialoglycoprotein (ASG) receptors was evaluated in vitro with use of two novel assays: relaxation time measurements of incubated human cell membrane solutions and iron staining of biopsy samples. Specific uptake of ASG receptor-directed agents was demonstrated in human samples of normal liver tissue, areas of hepatitis, regenerating nodules, areas of focal nodular hyperplasia, and hepatic adenomas. A conventional iron oxide preparation not directed at ASG receptors failed to demonstrate specific uptake in these tissues. Attachment of the ASG receptor-directed agents was competitively blocked with a receptor agonist (D(+)-galactose) in these tissues. No attachment of conventional or receptor agents was seen in areas of hepatocellular carcinoma, cholangiocarcinoma, or liver metastases. The studies indicate that in vitro receptor assays are useful in predicting the affinity of new receptor-directed MR imaging contrast agents in human tissue prior to clinical trials.

Asialoglycoprotein Receptor↗
PubMed1992

[Primary sonographic diagnosis and follow-up of muscular and tendon injuries of the lower extremity].

Ultrasound examination has become an important diagnostic method in muscle and tendon injuries. In addition dynamic ultrasound examination allows evaluation of the course of healing from various aspects. Starting with the sonoanatomy, the pathologic ultrasound patterns typical for injuries to muscle and to Achilles, patellar and quadriceps tendons are demonstrated. As complement to clinical examination, ultrasonography enables appropriate adaptation of the therapy concept to the course of healing. In the hands of experienced operators, ultrasound examination has reached a high level of sensitivity and specificity in these injuries and can justifiably be routinely performed.

Achilles Tendon↗
PubMed1991

Sonography and scintigraphy in the diagnosis of diseases of the major salivary glands.

This is a prospective study of 73 patients with diseases of the major salivary glands. The sonographic diagnosis could be confirmed by the course of the disease and/or the histologic result after operation in 67 (93%). In 29 patients, salivary gland scintigrams also were carried out. There was a tendency for signs of hypervascularization to be seen in patients with acute inflammation and reduction or loss of function in the presence of a chronic inflammation of the salivary glands. Scintigraphy did not provide diagnostic information on tumors of the salivary glands with regard to the type and location, with the exception of the Warthin's tumor. In selected cases it adds additional information, especially in functional therapy control.

Adenoma, Pleomorphic↗
PubMed1991

Use of sonography in the follow-up of preoperatively irradiated efferent lymphatics of the neck in oropharyngeal tumours.

The applicability of sonography in the control of preoperative radiotherapy of neck lymph nodes in patients with malignancies in the region of the head and the neck was established in a prospective study. Lymph nodes with positive reactions showed a simultaneous reduction in size and structure. Postoperative histology showed no malignancy in these lymph nodes. All metastases were found in lymph nodes without sonographic changes under irradiation. In establishing the surgical procedure, clinical criteria should be considered primarily, and these should be supplemented and completed by the sonographic investigation.

Carcinoma↗
PubMed1991

Growth of lung allografts after experimental transplantation.

Heart and lung transplantation has been performed in cases of end-stage cardiopulmonary disease in infants. Nevertheless, it still remains unclear whether lung allografts adjust to a growing organism. In 6 young domestic pigs unilateral left lung allotransplantation was performed. Immunosuppression consisted of a triple drug therapy including cyclosporine, azathioprine, and corticosteroids. Lung growth was studied by using bronchography, pulmonary angiography, and lung histology. After 11 weeks the transplanted animals had doubled their body weight from 24 kg to 48 kg. Non-transplanted animals in contrast doubled their weight within only 6 weeks. The growth retardation was attributed to the immunosuppressive therapy. The bronchial tree and pulmonary vasculature of lung allografts showed a similar growth potential to non-transplanted lungs in animals of equivalent body weight. In one case of recurrent severe rejection of the lung no growth was observed. Therefore it was concluded that lung allografts grow adequately according to the development of the recipient organism. Lung transplantation in children does not seem to be restricted by a limited growth potential of the graft.

Animals↗
PubMed1991

Asialoglycoprotein receptor function in benign liver disease: evaluation with MR imaging.

An arabinogalactan-coated ultrasmall superparamagnetic iron oxide (AG-USPIO) preparation specific for asialoglycoprotein (ASG) receptors on hepatocytes was used as a magnetic resonance (MR) imaging contrast agent in the evaluation of a spectrum of benign liver diseases in animal models. The activity of hepatocyte ASG receptors, which directly reflects liver function, was directly assessed by measuring liver relaxation times in vitro and MR signal intensity in vivo. The following measurements allowed three-dimensional assessment of liver function: (a) liver relaxation time, (b) native MR signal intensities of liver, (c) response of liver to the AG-USPIO probe (percentage decrease of liver signal intensity after intravenous administration of 10 mumol/kg of AG-USPIO: normal liver 55%, fatty liver 57%, acute hepatitis 36%, chronic hepatitis 29%, and cirrhosis 46%), and (d) redistribution of hepatocyte-specific AG-USPIO to the spleen (present in hepatitis and cirrhosis but not in normal liver and fatty liver). The results of this study indicate that cellular hepatic abnormalities can be detected and quantitated with MR receptor imaging.

Animals↗
PubMed1991

Bone marrow: ultrasmall superparamagnetic iron oxide for MR imaging.

An ultrasmall superparamagnetic iron oxide (USPIO) preparation was evaluated as a potential intravenous contrast agent for magnetic resonance (MR) imaging of bone marrow. One hour after administration of USPIO (40, 80, and 160 mumols of iron per kilogram body weight) in rats and rabbits, T1 and T2 relaxation times were, respectively, approximately 30%, 50%, and 65% lower than precontrast relaxation times. Maximum decrease in relaxation times of marrow occurred within 1-24 hours after intravenous administration; thereafter, relaxation times slowly returned to normal within 7 days. In vivo MR imaging of rabbits and rats confirmed that USPIO decreases signal intensity of red and yellow marrow. The decrease was most marked with gradient echo pulse sequences. An animal model of intramedullary tumor demonstrated the potential of USPIO to enable differentiation between tumor and normal red marrow. USPIO-enhanced MR imaging improves detection of smaller tumors and allows differentiation of tumor deposits from islands of hyperplastic or normal red marrow.

Animals↗
PubMed1991

Experimental hepatocellular carcinoma: MR receptor imaging.

Relaxation time measurements and magnetic resonance (MR) imaging were performed in three different animal models of hepatocellular carcinoma (HCC). After intravenous administration of asialoglycoprotein-directed arabinogalactan-stabilized ultrasmall superparamagnetic iron oxide (10 mumol Fe/kg receptor agent), T2 of normal liver decreased from 41.6 msec +/- 1.0 to 19.4 msec +/- 1.7 (P less than .05) in rats. T2 of HCC implanted in normal liver or liver with chronic hepatitis was essentially unchanged. These results were similar to those obtained by administration of a reticuloendothelial cell-directed conventional iron oxide; however, the required dose of receptor agent was lower. MR imaging in a woodchuck model of virally induced HCC confirmed the distribution of the hepatocyte-directed agent to regions of functioning and differentiated hepatocytes but not to malignant tumor tissue. The results suggest that MR receptor imaging may play a role in the differentiation between primary liver tumor and functional liver tissue such as that in normal liver hepatitis or regenerating nodules.

Animals↗
PubMed1991

Polyclonal human immunoglobulin G labeled with polymeric iron oxide: antibody MR imaging.

Human polyclonal immunoglobulin (Ig) G was attached to a monocrystalline iron oxide nanocompound (MION), a small superparamagnetic probe developed for receptor and antibody magnetic resonance (MR) imaging. The resulting complex, MION-IgG, had a slightly negative surface charge, a molecular weight of 150-180 kDa, and 0.36 microgram of IgG attached per milligram of iron. After intravenous administration of MION-IgG to normal rats, most of the compound localized in liver, spleen, and bone marrow. In an animal model of myositis, MION-IgG caused reduced signal intensity (most apparent on T2-weighted spin-echo and gradient-echo images) at the site of inflammation. No change in signal intensity existed after an injection of unlabeled MION. Site-specific localization of MION-IgG was corroborated with scintigraphic imaging with indium-111 IgG and MION-In-111-IgG and was confirmed histologically with iron staining. These results indicate that antibody MR imaging is feasible in vivo. Target-specific and antibody MR imaging could be easily extended to other applications, including detection of cancer, infarction, and degenerative diseases.

Animals↗
PubMed1991

[The diagnostic potentials of color-coded Doppler sonography in space-occupying lesions in the head-neck area].

In our experience, B-mode sonography proved to be a valuable method in diagnosis of tumours in the head and neck region. Especially in diagnosis of space-occupying lesions in children we consider it as method of choice. A case report illustrates the efficiency of angiodynography in providing further information about vascular malformations in the floor of the mouth with regard to dignity and extension of the space occupying lesion. Tumourous infiltration of vessel walls by malignant tumours or metastatic lymph nodes and hemodynamic consequences of these pathologic processes in anatomic neighbourhood to these vessels can be visualized. In our short period of experience, angiodynography seems to be a quick non-invasive and non-ionizing imaging technique which is very suitable in evaluation of vascular lesions in the floor of the mouth and tongue region.

Color↗
PubMed1990

[Ultrasonic evaluation of homologous bone and cartilage transplants of the femoral condyles].

Evaluation of the weight-bearing articular cartilage of the femoral condyles is possible by sonography. Bone and cartilage transplants can be examined by conventional radiological methods combined with sonography. This provides clinically relevant information. Sonography is a cheap imaging method for providing additional information on the post-operative course of cartilage transplants.

Adult↗
PubMed1990

[Experimental meniscus sonography: the influence of imaging geometry on the visualization of meniscal lesions].

Specific meniscal tears were set on prepared cadaver knees to examine the influence of projection factors on the visualisation of these lesions via ultrasound. 7.5 MHz sector- and linear scanner were used. It showed that both the extent of the lesion and also the angle between outgoing echo-direction and reflection plane determines the sonographic findings of meniscal tears. Adapted horizontal tears and vertical radial tears were often not seen. Concentric vertical lesions showed one or two high echogenic lines, depending on the extent of the defect. So it seems that there are limits for an exact sonographic characterization of meniscal lesions.

Evaluation Studies as Topic↗
PubMed1990

[Chemical embolization of carcinoid metastases in the liver].

We performed chemo-embolisation with gel foam powder and epirubicin in 11 symptomatic patients with liver metastases from carcinoids. In all cases the symptoms regressed completely after the procedure. In two patients the liver was re-embolised because of tumour growth and both again became symptom-free. In one case, increasing extra-hepatic tumour growth was treated with interferon. One female patients died seven days after the procedure from renal failure and from complications of cerebral oedema. Two other patients died from extensive extra-hepatic tumour in the skeleton and lungs at 88 and 97 weeks after embolisation, respectively. The remaining patients are still symptom-free at 18 to 161 weeks.

Adult↗
PubMed1990

[Postoperative diagnosis following separate replacement of an aortic valve and an ascending aorta using IV-DSA and CT].

We performed a follow-up examination by intravenous DSA and dynamic CT of 14 patients with separate replacement of aortic valve and ascending aorta due to an aneurysm or an aortic dissection. In 5 patients, we found an aortic ectasia at the aortic bulb or a perfused "graft inclusion". Both are best demonstrated with dynamic CT. As a result of the study, the operation technique was changed. In the postoperative management of patients with separate replacement of aortic bulb and ascending aorta, careful monitoring by dynamic CT is necessary even in the absence of clinical symptoms.

Adult↗
PubMed1990

Storage phosphor versus screen-film radiography: effect of varying exposure parameters and unsharp mask filtering on the detectability of cortical bone defects.

Diagnostic performance with storage phosphor radiography is influenced by exposure parameters and digital filtering algorithms. The authors compared the detectability of cortical lesions in excised human femoral shafts on state-of-the-art screen-film radiographs and storage phosphor digital radiographs. For the digital system, the effect of varying exposure parameters (photon flux and tube voltage) and unsharp mask filtering (kernel size and enhancement factor) was tested. Analysis of receiver operating characteristics was performed for 10,560 observations made by eight radiologists. Under identical exposure conditions, storage phosphor imaging yielded no significant advantages over conventional screen-film radiography. Although large variations in exposure dose are possible with storage phosphors, the potential for dose reduction was limited even by means of an increase in tube voltage. The performance with unsharp masked images declined with decreasing kernel size and pronounced enhancement.

Bone and Bones↗