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K Elsner

Publications and source records attributed to K Elsner.

17 recordsLinked to original sources
PubMed2004

Calculation of the persistence length of a flexible polymer chain with short-range self-repulsion.

For a self-repelling polymer chain consisting of n segments we calculate the persistence length L (j,n), defined as the projection of the end-to-end vector on the direction of the j-th segment. This quantity shows some pronounced variation along the chain. Using the renormalization group and epsilon-expansion we establish the scaling form and calculate the scaling function to order epsilon 2. Asymptotically, the simple result L (j,n) approximately const [j(n-j)/n]2nu-1 emerges for dimension d = 3. Also away from the excluded-volume limit L (j,n) is found to behave very similar to the swelling factor of a chain of length j (n-j)/n. We carry through simulations which are found to be in good accord with our analytical results. For d = 2 both our and previous simulations as well as theoretical arguments suggest the existence of logarithmic anomalies.

Journal Article↗
PubMed2001

2-(fluorine-18)fluoro-2-deoxy-D-glucose positron emission tomography in the detection and staging of malignant lymphoma. A bicenter trial.

BACKGROUND: The authors undertook a prospective evaluation of the clinical value of 2-fluoro [18-]-2-deoxyglucose positron emission tomography (FDG-PET) in the detection and staging of malignant lymphoma compared with computed tomography (CT) and bone marrow biopsy (BMB). METHODS: Fifty-two consecutive patients with untreated malignant lymphoma were evaluated prospectively in a bicenter study. FDG-PET, CT, and BMB were performed for investigating lymph node/extranodal manifestations and bone marrow infiltration. Thirty-three percnt of the discrepant results were verified by biopsy, magnetic resonance imaging, or clinical follow-up (range, 4-24 month). RESULTS: Altogether, 1297 anatomic regions (lymph nodes, organs, and bone marrow) were evaluated. FDG-PET and CT scans were compared by receiver operating characteristic (ROC) curve analysis. The area under the ROC curve were as follows: lymph nodes, 0.996 (PET) and 0.916 (CT); extranodal, 0.999 (PET) and 0.916 (CT); supradiaphragmatic, 0.996 (PET) and 0.905 (CT); and infradiaphragmatic, 0.999 (PET) and 0.952 (CT). In these analyses, FDG-PET was significantly superior to CT (P < 0.05), except in infradiaphragmatic regions, in which the two methods produced equivalent results. In detecting bone marrow infiltration, FDG-PET was superior to CT and was equivalent to BMB. In 4 of 52 patients (8%), FDG-PET led to an upstaging and a change of therapy. CONCLUSIONS: Noninvasive FDG-PET is very accurate in the staging of malignant lymphoma. Compared with standard staging modalities (CT and BMB), PET was significantly superior and led to changes in the therapy regimen for 8% of patients.

Adolescent↗
PubMed2001

[Compartment syndrome of the triceps brachii muscle after intramedullary nailing].

We report a case of a humerus fracture with rare acute compartment syndrome of the triceps muscle after intramedullary nailing. Clinical (neurological) symptoms and measuring of the subfascial pressure of both triceps lead to early diagnosis. After immediate dermatofasciotomy we obtained full recovery of the radial nerve function.

Adult↗
PubMed1999

Positron emission tomography with 18-fluorodeoxyglucose in the staging and follow-up of lymphoma in the chest.

The purpose of this retrospective study was to evaluate the accuracy of positron emission tomography (PET) using 18-F-fluorodeoxyglucose (FDG) in predicting lymphomatous involvement in the hilar and mediastinal regions in the staging and follow-up of patients with malignant lymphoma. One hundred forty-seven thoracic PET studies in 89 consecutive lymphoma patients were reviewed. Static FDG-PET imaging was performed following application of 270 MBq FDG (mean). Results of FDG-PET were compared with the findings of computed tomography (CT) in all patients and clinical follow-up examination. Eighty-nine of 147 (60%) PET studies showed no FDG uptake in the hilar or mediastinal regions, while 58 (40%) studies did detect FDG uptake in these regions. In 52 of 58 abnormal studies (90%), lymphomatous involvement of the hilar and/or mediastinal regions seen by CT was present. In the remaining six abnormal PET studies (10%), FDG uptake was considered as false-positive because of missing lesions on corresponding CT scans. In four patients false-positive FDG uptake was observed before treatment, in two patients after completion of therapy. In these two patients FDG uptake after therapy was caused by thymus hyperplasia. The remaining four cases before treatment remained unresolved. Sensitivity of FDG-PET was 96%, specificity 94%, positive predictive value 90%, and negative predictive value 98%, respectively. The present study suggests that FDG-PET has potential value in predicting lymphomatous involvement in the hilar and mediastinal regions. FDG-PET may obviate invasive diagnostic procedures in patients with lymphoma.

Adolescent↗
PubMed1999

Early detection and accurate description of extent of metastatic bone disease in breast cancer with fluoride ion and positron emission tomography.

PURPOSE: Previous studies have shown that bone metastases are revealed by magnetic resonance imaging (MRI) or bone marrow scintigraphy several months before they are visible by conventional bone scintigraphy (BS). We present a new approach for detecting bone metastases in patients with breast cancer. We compared findings obtained with fluoride ion (F-18) and positron emission tomography (PET) with those obtained with conventional BS. PATIENTS AND METHODS: Thirty-four breast cancer patients were prospectively examined using F-18-PET and conventional BS. F-18-PET and BS were performed within 3 weeks of each other. Metastatic bone disease was previously known to be present in six patients and was suspected (bone pain or increasing levels of tumor markers, Ca(2+), alkaline phosphatase) in 28 patients. Both imaging modalities were compared by patient-by-patient analysis and lesion-by-lesion analysis, using a five-point scale for receiver operating characteristic (ROC) curve analysis. A panel of reference methods was used, including MRI (28 patients), planar x-ray (17 patients), and spiral computed tomography (four patients). RESULTS: With F-18-PET, 64 bone metastases were detected in 17 patients. Only 29 metastases were detected in 11 patients with BS. As a result of F-18-PET imaging, clinical management was changed in four patients (11.7%). For F-18-PET, the area under the ROC curve was 0.99 on a lesion basis (for BS, it was 0.74; P <.05) and 1.00 on a patient basis (for BS, it was 0.82; P <.05). CONCLUSION: F-18-PET demonstrates a very early bone reaction when small bone marrow metastases are present, allowing accurate detection of breast cancer bone metastases. This accurate detection has a significant effect on clinical management, compared with the effect on management brought about by detection with conventional BS.

Adult↗
PubMed1999

Sensitivity in detecting osseous lesions depends on anatomic localization: planar bone scintigraphy versus 18F PET.

UNLABELLED: Radionuclide bone scanning (RNB) is considered to be the most practical screening technique for assessing the entire skeleton for skeletal metastases. However, RNB has been shown to be of lower sensitivity than MRI and CT in detecting osteolytic metastases. A prospective study was designed to evaluate the accuracy of planar RNB versus tomographic bone imaging with 18F-labeled NaF and PET (18F PET) in detecting osteolytic and osteoblastic metastases and its dependency on their anatomic localization. METHODS: Forty-four patients with known prostate, lung or thyroid carcinoma were examined with both planar RNB and 18F PET. A panel of reference methods including MRI of the spine, 1311 scintigraphy, conventional radiography and spiral CT was used as the gold standard. RNB and 18F PET were compared by a lesion-by-lesion analysis using a five-point score for receiver operating characteristic (ROC) curve analysis. RESULTS: 18F PET showed 96 metastases (67 of prostate carcinoma and 29 of lung or thyroid cancer), whereas RNB revealed 46 metastases (33 of prostate carcinoma and 13 of lung or thyroid cancer). All lesions found with RNB were also detected with 18F PET. Compared with 18F PET and the reference methods, RNB had a sensitivity of 82.8% in detecting malignant and benign osseous lesions in the skull, thorax and extremities and a sensitivity of 40% in the spine and pelvis. The area under the ROC curve was 0.99 for 18F PET and 0.64 for RNB. CONCLUSION: 18F PET is more sensitive than RNB in detecting osseous lesions. With RNB, sensitivity in detecting osseous metastases is highly dependent on anatomic localization of these lesions, whereas detection rates of osteoblastic and osteolytic metastases are similar. Higher detection rates and more accurate differentiation between benign and malignant lesions with 18F PET suggest the use of 18F PET when possible.

Bone Neoplasms↗
PubMed1999

[F-18-FDG PET for primary diagnosis differential diagnosis of pleural processes].

PURPOSE: Positron emission tomography (PET) with 18-fluorodeoxyglucose (FDG) has been shown to be accurate for differentiating benign from malignant pulmonary lesions. Therefore, we evaluated the capability of FDG-PET in the characterisation of pleural lesions. PATIENTS AND METHODS: PET was performed in thirteen patients with pleural or intrapulmonal tumors (three with additional pleural effusion) and in three patients with aetiologically unclear pleural effusion demonstrated by CT. In all cases the diagnosis was confirmed histologically. The PET-imaging was carried out in fasted patients 50 minutes after injection of 400-670 MBq F-18-FDG without attenuation correction. RESULTS: Twelve patients were found to have pleural or pulmonal malignomas (9 pleural mesotheliomas, 3 bronchogenic adenocarcinoma with carcinomatous pleurisy). Four patients had benign pleural changes (1 fibroma, 1 tuberculous pleurisy, 1 pleural fibrosis, 1 empyema). With FDG-PET, all 12 pleural or intrapulmonal malignomas had high FDG-uptake and were classified correctly. Due to very low or virtually deficient FDG-uptake, four histologically benign lesions were correctly interpreted as nonmalignant. CONCLUSION: These preliminary results suggest that FDG-PET is accurate in detecting malignant pleural tumors.

Adult↗
PubMed1998

Whole-body 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) for accurate staging of Hodgkin's disease.

BACKGROUND: Staging of Hodgkin's disease (HD) is accomplished by a variety of invasive and non-invasive modalities. This prospective study was undertaken to investigate the value of whole-body positron emission tomography (PET) with 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) in defining regions involved by lymphoma compared with conventional staging methods in patients with HD. PATIENTS AND METHODS: Fourty-four newly diagnosed patients with HD underwent FDG-PET as part of their initial staging work-up. PET findings were correlated with findings of conventional staging including computed tomography, ultrasound, bone scanning, bone marrow biopsy, liver biopsy and laparotomy. When results of FDG-PET differed to those obtained by conventional methods reevaluation was performed by biopsy, if possible, or magnetic resonance imaging. RESULTS: The results of FDG-PET were compared with three hundred twenty-one conventional staging procedures performed in 44 patients. FDG-PET was positive in 38 of 44 (86%) patients at sites of documented disease. PET detected additional lesions in five cases previously not identified by conventional staging methods. In another case a nodal lesion suspect on CT was negative at FDG-PET and was settled as true negative by biopsy. As a consequence of PET findings five patients had to be upstaged and one patient had to be downstaged, resulting in changes in treatment strategy in all six cases (14%). FDG-PET failed to visualize sites of HD in four patients. In two of our patients a false positive PET result was obtained. CONCLUSIONS: Our data indicate that FDG-PET provides an imaging technique that appears to visualize involved lesions in most patients with HD and is useful in the management of these patients.

Adolescent↗
PubMed1997

[A new method in the determination of individual delay time in bolus application in spiral CT].

Helical-CT examinations, particularly CT angiography, require precise timing between the examination procedure and the individual dynamics of contrast medium distribution in the arteriovenous system of the patient. The necessary delay between contrast medium injection and onset of has usually been either estimated or determined by means of an additional helical CT examination. The present paper introduces a new technique which allows bolus analysis without an additional scan. Prior to a CT angiography with 10 patients, two techniques for bolus analysis (BA) were compared. Prior to diagnostic contrast medium enhanced examination, a native (BA I) and a dynamic (BA II) examination were performed. Ten seconds prior to the start of each examination, a 10 ml test bolus was applied with an injection flow rate of 3 ml/s. Both examinations lasted for 30 s. During BA I, increase in attenuation in the aorta was compared at different sites, during BA II consistently at the same site. Comparison of the individual peak times yielded a coefficient of correlation of r = 0.926. The median value for BA I was 18.4 +/- 5.4 s and 19.2 +/- 4.5 s for BA II. The difference between measurement of peak time was 1.2 +/- 1.16 s. This modified technique for bolus analysis during the primary native scan of the upper abdominal organs permits calculation of the required individual delay time between contrast medium application and scan start: no additional examination is required and the method can be performed with any helical CT unit.

Adult↗
PubMed1982

Arm pain in a dentist: pronator syndrome.

A 29-year-old pregnant dentist developed acute right forearm pain and associated weakness in her hand. A diagnosis of pronator syndrome was made. A review of the anatomy, pathophysiology, and treatment of pronator syndrome is given. We present this case to alert dentists, both male and female, of an uncommon but definite occupational hazard.

Adult↗