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Biomedical subjects

H Köhn

Publications and source records attributed to H Köhn.

At least 19 recordsLinked to original sources
PubMed2003

Sentinel lymph node detection with large human serum albumin colloid particles in breast cancer.

Detection of metastatic involvement of lymph nodes is essential for management and prognostic evaluation in breast cancer patients. The success of lymphatic mapping depends on identifying the sentinel lymph node(s) draining the primary tumour. However, when mapping is performed with a radiocolloidal agent, the number of hot lymph nodes varies with the agent and its size, among other factors. In this study, we evaluated prospectively the detection rate of sentinel lymph nodes in breast cancer when injecting large particles (100-600 nm) of human serum albumin colloids (Senti-Scint). In 128 consecutive breast cancer patients without palpable lymph nodes, pre-operative static lymphoscintigraphic mapping of the breast was performed after subcutaneous injection of 15 MBq of the radiocolloid. Lymphoscintigrahic results were compared with intra-operative surgical gamma detection probe and blue dye mapping data. Pre-operative lymphoscintigraphy and surgical gamma detection probe both correctly detected 203 sentinel lymph nodes in 122/128 patients (95%), while blue dye mapping showed only 183 sentinel lymph nodes in 82% of the patients. Only one or two sentinel lymph nodes were identified in each patient, which allowed the surgeon easily to find the sentinel lymph node(s) intra-operatively. In conclusion, lymphoscintigraphy with large particles of human serum albumin colloids is a helpful and reliable procedure for the surgical management of breast cancer.

Adult↗
PubMed2001

[Determination of therapy management in rectal carcinoma by staging with 18-FDG-PET].

The curative treatment of carcinoma of the rectum in the early stage of the disease is radical local surgery. If there is a solitary liver metastasis, resection is also a curative treatment. This report describes a female patient with rectal carcinoma, in whom a solitary liver metastasis in the left lobe was diagnosed only by FDG-PET and verified at surgery. This case report demonstrates the potential role of FDG-PET even for primary staging in detecting occult hepatic and extrahepatic metastases, thus significantly influencing the therapeutic management and prognosis of these patients.

Adenocarcinoma↗
PubMed2001

Regional cerebral blood flow in patients suffering from post-traumatic stress disorder.

OBJECTIVE: The aim of the study was to determine whether regional cerebral blood flow in survivors of torture suffering from post-traumatic stress disorder (PTSD) differed significantly from that in healthy controls. METHOD: We examined the cerebral regional distribution of 99m-technetium-hexamethylpropyleneamineoxime (HMPAO) using single photon emission computed tomography (SPECT) in 8 patients and in 8 healthy controls. A semi-quantitative analysis was performed in which symmetrical regions of interest (ROI) were drawn in all subjects. RESULTS: Regional blood flow was markedly more heterogeneous in patients suffering from PTSD than in healthy controls. The differences are significant. CONCLUSION: Severe psychological trauma induced by torture can cause neurobiologic alterations that may contribute, even years after the original trauma, to a number of complaints commonly expressed by patients suffering from PTSD.

Adult↗
PubMed2000

Distributed nuclear medicine applications using World Wide Web and Java technology.

At present, medical applications applying World Wide Web (WWW) technology are mainly used to view static images and to retrieve some information. The Java platform is a relative new way of computing, especially designed for network computing and distributed applications which enables interactive connection between user and information via the WWW. The Java 2 Software Development Kit (SDK) including Java2D API, Java Remote Method Invocation (RMI) technology, Object Serialization and the Java Advanced Imaging (JAI) extension was used to achieve a robust, platform independent and network centric solution. Medical image processing software based on this technology is presented and adequate performance capability of Java is demonstrated by an iterative reconstruction algorithm for single photon emission computerized tomography (SPECT).

Image Processing, Computer-Assisted↗
PubMed2000

A Jini service to reconstruct tomographic data.

Distributed computing that uses dynamic networks will change the way we work and communicate thanks to the interaction of devices and services, that are automatically added and removed from the network as needed. The Jini technology, which is built atop the Java programming language, provides a homogenous view of the network and extends the ability of code to migrate in Java. This software design model simplifies the configuration and access to hardware devices and software services in a network. Thus, it becomes possible to execute new services without pre-installing software on client machines. This new programming paradigm is especially important in medical applications, where the reliable transmission of information is essential. This paper demonstrates how single photon emission computerized tomography data can be iteratively reconstructed using a Jini service.

Computer Communication Networks↗
PubMed1999

An artificial neural net and error backpropagation to reconstruct single photon emission computerized tomography data.

At present, algorithms used in nuclear medicine to reconstruct single photon emission computerized tomography (SPECT) data are usually based on one of two principles: filtered backprojection and iterative methods. In this paper a different algorithm, applying an artificial neural network (multilayer perception) and error backpropagation as training method are used to reconstruct transaxial slices from SPECT data. The algorithm was implemented on an Elscint XPERT workstation (i486, 50 MHz), used as a routine digital image processing tool in our departments. Reconstruction time for a 64 x 64 matrix is approximately 45 s/transaxial slice. The algorithm has been validated by a mathematical model and tested on heart and Jaszczak phantoms. Phantom studies and very first clinical results ((111)In octreotide SPECT, 99mTc MDP bone SPECT) show in comparison with filtered backprojection an enhancement in image quality.

Algorithms↗
PubMed1999

Possible effect of calcitonin deficiency on bone mass after subtotal thyroidectomy.

Bone mass is purportedly reduced by an excess of endogenous or exogenous thyroid hormone or perhaps by calcitonin deficiency. Patients who have undergone thyroidectomy could be subject to all of these effects. In the present study we tried to demonstrate, whether lack of calcitonin following thyroidectomy has a significant influence on bone density. We measured thyroid hormone levels, TSH and calcitonin and assessed the bone mass in the hip and lumbar spine of 55 patients (32 f, 23 m), who had undergone a subtotal thyroidectomy between 1938 and 1996 on the reason of a non-toxic goitre. TSH levels were suppressed in 16 patients. Serum concentration of total calcium, intact PTH, osteocalcin were normal in all subjects. The mean fasting calcitonin level was in the patient group 2.09 +/- 0.7 pg/ml and in the control group, age matched healthy volunteers, 2.8 +/- 1.2 pg/ml. However, the serum level of calcitonin was not significantly lower than in the control group. 43 patients had an osteopenia or osteoporosis. The interpretation of the results in this study is hampered by the fact, that in women results may be influenced by involutional osteoporosis. Therefore we focus on the potential for osteoporosis among the 23 men. The results of our study indicates, that there is a significant reduction in bone mass in male after thyroidectomy, no matter whether T4 therapy is given or not, and whether TSH is suppressed or in a normal range.

Adult↗
PubMed1998

Bone scintigraphy in screening of torture survivors.

BACKGROUND: In most developed countries, survivors of physical torture inflicted for political, religious, or ethnic reasons face ever more stringent review when seeking asylum. In Austria, asylum seekers are required by immigration authorities to undergo medical examination as part of the review. Bone scintigraphy can detect bone lesions that are not detectable clinically or radiologically. We assessed the value of bone scintigraphy as corroboration of alleged injuries. METHODS: Human-rights organisations referred 25 asylum seekers to us from countries where torture is practised. We included patients who claimed to have been beaten by the security forces in their home country because of political or religious conviction or ethnic origin. Injuries had been inflicted 4 months to 5 years earlier. The patients (three women, 22 men) from 12 countries were categorised retrospectively into two groups: group A (n=12), tortured with blows from hard objects, and group B (n=13), tortured with blows from fists and kicks. We also used a control group of 25 individuals with the same age and sex distribution from the same countries who had no history of torture. FINDINGS: In group A, bone scans showed abnormalities in the area of alleged injury in all patients, whereas radiography was positive in only five patients. In group B, bone scans in the alleged areas of damage were positive in seven patients, but radiography yielded no positive outcomes. Among the controls there was one abnormal scan due to a known coxarthrosis. INTERPRETATION: Our preliminary results suggest that bone scintigraphy is a sensitive, non-invasive tool to document trauma some years after the actual injury.

Bone and Bones↗
PubMed1998

The incidence of hyperthyroidism in Austria from 1987 to 1995 before and after an increase in salt iodization in 1990.

Between 1963 and 1990, Austria had iodized salt prophylaxis of endemic goitre with 10 mg KI (7.5 mg I) per kg. This was obviously insufficient, as urinary iodine excretion ranged from 42 to 78 microg I per g of creatinine and goitre in adults remained in the endemic range of 15%-30%. Therefore salt iodization was doubled in 1990. The aim of this study was to assess the annual incidence of different types of hyperthyroidism (HT) before and after this increase in salt iodization. The incidence of HT was recorded in 14 nuclear medicine centres from 1987 to 1995. In five additional centres data were available from 1992 onwards. Data prior to 1992 were documented retrospectively, while those after 1992 were recorded prospectively. The 14 centres drew patients from an area with a population of approximately 4.23 million while all 19 institutes were estimated to cover an area with a population of 5.4 million (the total population of Austria is 7.86 million). A total of 414232 persons were examined for the first time in the participating centres. HT and the type of HT were defined by clinical examination, serum TSH, thyroid hormone levels in blood, ultrasonography, scintigraphy and serum autoantibody titres. HT was classified into immunogenic HT (Graves' or Basedow's disease, GD) and HT with intrinsic thyroid autonomy (uni-, multinodular or disseminated Plummers' disease, PD). HT was also divided into overt (o) or subclinical (sc) disease. The following data were calculated: annual incidence per 100000 and the relative risk (RR) for HT with 95% confidence intervals (CI). In addition, linear trends were calculated for each type of HT by means of logistic regressions. In the 19 centres a total of 47834 patients with HT were registered from 1987 to 1995. PD accounted for 75% of all cases of HT and GD for 19%, while other types of HT were present in 6%. From 1987 to 1989 (time period T0), the annual incidence of oPD was 30.5 (95% CI 29.6-31.5) per 100000. The RR compared to the baseline period T0 was highest in 1992 (1.37; 1.3-1.45) and decreased to 1.17 (1.1-1.24) in 1995. The annual incidence of scPD in T0 was 27.4 (26.5-28.3) per 100000. The RR was highest in 1991 (1.64; 1.56-1.73) and was 1.60 (1. 51-1.69) in 1995. In oPD and scPD a higher RR was observed in persons older than 50 years of age, particularly in men. The incidence of oGD in T0 was 10.4 (9.8-10.9) per 100000; the maximum RR increased to 2.19 (2.01-2.38) in 1993 and decreased to 1.95 (1.78-2.13) in 1995. The incidence of scGD was 1.9 (1.6-2.1) in T0. The maximum RR was observed in 1994 (2.47; 2.04-3.0) and it was still 2.26 (1.85-2.77) in 1995. The increased incidence of oGD and scGD was evenly distributed in all ages and both sexes. The time course of different types of HT following the increase in salt iodization could be divided into two phases: an increase in the incidences of HT with peaks after 1-4 years and a subsequent decrease, the only exception being scGD. The effect was more pronounced in GD than in PD. PD showed an age and gender dependency over time, while GD did not.

Adult↗
PubMed1998

[Value of inflammation and bone scintigraphy in differential diagnosis of painful affections of small joints].

It was the aim of this study to evaluate different markers of inflammation such as 99mTc-labelled human immunoglobulin G and 99mTc-nanocolloid with respect to their ability to detect inflammatory or degenerative affections of small joints of hand and fingers. While conventional bone scanning reveals good agreement with clinical findings it is not well suited for screening of inflammatory processes due to its poor specificity. In small joints conventional three-phase bone scan with information of perfusion, bloodpool and accumulation is not suitable due to the small ROI, low count rate with high statistics. Therefore we used inflammatory markers to overcome this problem. Immunoglobulin G was true positive in case of inflammatory lesions in 69%, and false positive in case of degenerative lesions in 24%, while nanocolloid was true positive in 72% and false positive in 14%, respectively. Significant differences were found between markers of inflammation and the bone scanning agent while both inflammatory markers, immunoglobulin G and nanocolloid demonstrated significant correlation. While bone scanning tracers detect all kinds of joint affections, immunoglobulin G and nanocolloid accumulate preferentially in inflammatory joints and therefore might be useful to differentiate between inflammatory and degenerative lesions.

Adult↗
PubMed1998

Decisive diagnosis of seronegative polyarthritis by 3-phase bone scintigraphy.

Inflammatory joint disease is mainly diagnosed on grounds of clinical investigation, laboratory testing (acute phase reactants), and radiography. Radionuclide imaging has recently been added to the armamentarium of clinician. This case report points out the role of three-phase bone scan and HIG (human immunoglobulin) scan in the discovery of the inflammatory nature of polyarthralgia in a young woman with equivocal clinical and laboratory results. In the aim of diagnosing arthritis early in its course scintigraphy proved to be superior to conventional radiography. It also allows more discriminating selection of subsequent X-ray examination to limit radiation exposure.

Acute-Phase Proteins↗