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Biomedical subjects

U Mödder

Publications and source records attributed to U Mödder.

At least 19 recordsLinked to original sources
PubMed2007

[Nonocclusive ischemia of the right colon].

BACKGROUND: Nonocclusive disease (NOD) is known to be a common cause of ischemic colitis, which is frequently underestimated. MATERIAL AND METHODS: A computer-assisted search of radiological reports at our institute over a period of 18 months, describing ischemic colitis of the ascending colon with an unimpaired perfusion of the superior mesenteric artery, was performed. RESULTS: A retrospective analysis of the clinical and radiological data of 14 patients was performed. In ten cases colonic ischemia was confirmed clinically or intraoperatively. Most of our patients needed intravenous catecholamines due to severe hypotension. However, no significant radiographic predictors could be identified. CONCLUSION: Awareness of NOD seems to be crucial. Especially in cases of acute abdominal pain associated with severe hypotension, renal insufficiency, or pancreatitis, one should include NOD as a differential diagnosis at an early stage.

Abdominal Pain↗
PubMed2006

Feasibility of ultra-low-dose multi-detector-row CT-colonography: detection of artificial endoluminal lesions in an in-vitro-model with optimization of image quality using a noise reduction filter algorithm.

PURPOSE: To assess the most favorable slice thickness in Multi-Detector-Row CT-colonography (MDCTC), and the feasibility of dose reduction in an in-vitro-setting as well as the possibility of optimization of image quality using a noise reduction filter algorithm. - MATERIALS AND METHODS: 18 artificial lesions with sizes from 1 to 8 mm were randomly positioned in two cleansed pig colons. At a "Somatom Plus 4 Volume Zoom", six scanning protocols using a slice collimation of 2.5, 1, and 1 mm with a reconstructed slice thickness of 3, 3, and 1.25 mm were performed with tube currents of 100, and 10 mAs, respectively. Using a non-commercial software, a non-linear Gaussian filter was used to minimize image noise. Image noise was assessed before and after application of the filtering process. Using a threshold of -750 HU, two blinded readers analyzed the virtual colonography in respect to lesion location, size, and shape. Artifacts were noted. An automated detection system was evaluated. - RESULTS: Using 10 mAs, a ten-fold dose reduction was achieved. After application of the mathematical filter, image noise was reduced by 45-80% for 100 mAs, and by 50-70% for 10 mAs scans. Only with a slice thickness of 1.25 mm, all lesions could be detected. The definition of lesion size and shape was more accurate with higher mAs. Only minor noise artifacts were noted on low-dose images. The automated polyp detector marked not more than 60% of artificial lesions. - CONCLUSION: MDCTC benefits from narrow slice collimation. In an in-vitro-model, a significant dose reduction is achievable with preservation of a high lesion detection rate. The noise reduction filter algorithm improved image quality substantially.

Algorithms↗
PubMed2006

High-resolution multipinhole single-photon-emission computed tomography in experimental and human arthritis.

OBJECTIVE: To image inflammatory arthritic lesions in experimental arthritis and in patients with arthritis, using a newly developed high-resolution multipinhole single-photon-emission computed tomography (MPH-SPECT) technique. METHODS: Six interleukin-1 receptor antagonist-deficient mice with arthritis of the front and back paws and 2 control BALB/c mice were imaged with MPH-SPECT and scored macroscopically for arthritis. SPECT imaging was performed with a conventional gamma camera upgraded with a pyramidal lead collimator affixed with MPH apertures. All images were reconstructed, and uptake in the paws was quantified in counts/weight and injected activity. To transfer the imaging technique to humans we examined the clinically dominant hand of 6 individuals (3 with established rheumatoid arthritis [RA], 1 with early RA, 1 with osteoarthritis, and 1 healthy control). RESULTS: MPH-SPECT images were high-resolution 3-dimensional tomographic images, which allowed exact localization and quantifiable observation of increased bone metabolism. MPH-SPECT counts of inflamed joints in mice correlated with macroscopic scoring and histologic joint analysis postmortem. In humans, MPH-SPECT images depicted a detailed visualization of tracer accumulation in bony structures of hand and finger joints, and were also capable of imaging increased bone metabolism that had appeared normal with other imaging modalities, e.g., magnetic resonance imaging. CONCLUSION: The MPH-SPECT technique represents a new diagnostic tool in the detection of bone pathology in small-animal arthritis research. Compared with macroscopic scoring, this new method provides a more objective and higher-precision quantifiable measurement of bone reaction, allowing visualization of inflammatory processes of the whole skeleton in vivo. These results suggest that MPH-SPECT may be useful as a diagnostic instrument for monitoring experimental arthritis, with further potential for use in human studies of RA.

Aged↗
PubMed2006

[Pre- and postnatal MRI of the fetus with complex intracranial vascular malformation].

Intracranial vascular malformations (IVM) on the whole occur in neonates very rarely. In such cases of IVM two different kinds can and must be discerned: (1) dural arteriovenous shunts (DAVS) and (2) vein of Galen aneurysmal malformations (VGAM). The latter seem to represent the majority of IVM of newborns. Several classifications are known for both types. Mortality of neonates and babies due to DAVS exceeds the average mortality from DAVS in adults. VGAM and DAVS can be diagnosed by prenatal ultrasonography only when the vessels behind the shunt are vasodilated because of the increasing flow stress. For that reason VGAM and DAVS are generally not recognized before the last trimenon or even postnatally. The prognosis of an IVM is influenced by the shunt capacity and its resulting cardiac stress as well as by the child's age. To plan the mostly interventional therapy, postnatal angiography (DSA) and MRI are employed and to an increasing extent also prenatal MRI examinations. We describe the case of a very complex IVM, the full dimensions of which could only be discerned by using pre- and postnatal MRI supplementary to the ultrasonography. Besides DAVS, flows from the pericallosal arteries as well as from the thalamic branches had to be considered. As a consequence DAVS and in addition VGAM existed in parallel.

Central Nervous System Vascular Malformations↗
PubMed2006

[Interactive thresholded volumetry of abdominal fat using breath-hold t1-weighted magnetic resonance imaging].

PURPOSE: Development of a feasible and reliable method for determining abdominal fat using breath-hold T1-weighted magnetic resonance imaging. MATERIALS AND METHODS: The high image contrast of T1-weighted gradient echo MR sequences makes it possible to differentiate between abdominal fat and non-fat tissue. To obtain a high signal-to-noise ratio, the measurements are usually performed using phased array surface coils. Inhomogeneity of the coil sensitivity leads to inhomogeneity of the image intensities. Therefore, to examine the volume of abdominal fat, an automatic algorithm for intensity correction must be implemented. The analysis of the image histogram results in a threshold to separate fat from other tissue. Automatic segmentation using this threshold results directly in the fat volumes. The separation of intraabdominal and subcutaneous fat is performed by interactive selection in a last step. RESULTS: The described correction of inhomogeneity allows for the segmentation of the images using a global threshold. The use of semiautomatic interactive volumetry makes the analysis more subjective. The variance of volumetry between observers was 4.6 %. The mean time for image analysis of a T1-weighted investigation lasted less than 6 minutes. CONCLUSION: The described method facilitates reliable determination of abdominal fat within a reasonable period of time. Using breath-hold MR sequences, the time of examination is less than 5 minutes per patient.

Abdomen↗
PubMed2006

Imaging characteristics of hepatocellular carcinoma using the hepatobiliary contrast agent Gd-EOB-DTPA.

PURPOSE: To evaluate the ability of contrast-enhanced magnetic resonance imaging (MRI) with Gd-EOB-DTPA in comparison with non-enhanced imaging and spiral computed tomography (CT) to provide additional information for classification and characterization of hepatocellular carcinoma. MATERIAL AND METHODS: Forty patients with histopathology-proven hepatocellular carcinoma were selected for this subgroup analysis from a phase-III multicenter study in 235 patients with known or suspected liver lesions. The primary analysis was comparison of the proportion of hepatocellular carcinoma correctly classified and characterized by combined pre-/post-contrast MRI compared with pre-contrast MRI alone or with spiral CT. All images were evaluated on site, and in a blinded reading by three independent readers off site. RESULTS: In the on-site evaluation, the lesions were correctly classified as a malignant tumor with combined MRI in 90.3%, with pre-contrast imaging alone in 82.9% and with spiral CT in 87.8% (n.s.). The proportion of correct characterization (lesion type diagnosis) with combined MRI was 85.4%, 75.6% for pre-contrast imaging, and 77.5% for spiral CT (n.s.), respectively. In the blinded reading, one reader showed a significant increase in the proportion of correctly characterized lesions by 27% (P<0.05). The other two readers showed a reduction in the proportion of correct characterization by 12% and 15%, respectively (n.s.). CONCLUSION: With regard to lesion classification, no difference was found between combined pre-/post-contrast MRI and spiral CT. A non-significant trend in favor of Gd-EOB-DTPA-enhanced MRI with regard to characterization of hepatocellular carcinoma was found, although the CT scans were not optimized as the MRI scans.

Adult↗
PubMed2006

1H-MR spectroscopy, magnetization transfer, and diffusion-weighted imaging in alcoholic and nonalcoholic patients with cirrhosis with hepatic encephalopathy.

PURPOSE: Mild swelling of astrocytes is proposed as a key event in the pathogenesis of hepatic encephalopathy. Proton MR spectroscopy ((1)H-MR spectroscopy), diffusion-weighted imaging (DWI), and magnetization transfer imaging were performed in patients with alcoholic and nonalcoholic liver cirrhosis and correlated with different clinical stages of hepatic encephalopathy to assess alterations in cerebral water metabolism in different subgroups of patients with cirrhosis. MATERIAL AND METHODS: Forty-five patients (26 alcoholics, 19 nonalcoholics [due to hepatitis C (n = 9), hemochromatosis (n = 2), primary chronic cholangitis (n = 2), hepatitis B (n = 1), Wilson disease (n = 1), cryptogenic cirrhosis (n = 4)]) and 18 controls underwent (1)H-MR spectroscopy, magnetization transfer imaging, and DWI of the basal ganglia and normally appearing occipital white matter (NAWM). N-acetylaspartate (NAA), choline (Cho), myo-inositol (mIns), and glutamine/glutamate (Glx) relative to creatine (Cr), the apparent diffusion coefficients (ADC), and the magnetization transfer ratios (MTR) were correlated to the neuropsychologic status, which was assessed by computerized psychometry and mental state grading, according to the West Haven criteria. RESULTS: Compared with controls, nonalcoholic subjects exhibited a gradual increase of Glx/Cr in the basal ganglia and NAWM; a decrease in mIns/Cr; a significant decrease of MTR in the thalamus, the putamen, the pallidum, and NAWM; and an increase in the ADC of the NAWM with increasing hepatic encephalopathy severity. In alcoholics, mIns/Cr of the basal ganglia and the NAWM, Cho/Cr of the basal ganglia, and MTR of all assessed regions were decreased. Glx/Cr of the basal ganglia and of the NAWM was increased, compared with that of controls; but no correlation to the clinical hepatic encephalopathy grading was found. ADC did not change significantly between the groups. CONCLUSIONS: Apart from a typical pattern of (1)H-MR spectroscopy alterations in hepatic encephalopathy, a gradual decrease in MTR and an increase of ADC was found correlating to clinical grading of hepatic encephalopathy in nonalcoholic patients with cirrhosis. In alcoholic patients with hepatic encephalopathy, there was no such correlation. Abnormalities detected by MR imaging may hint at different pathways of brain damage in alcohol-induced liver disease.

Diffusion Magnetic Resonance Imaging↗
PubMed2006

Radiation exposure of patients in comprehensive computed tomography of the head in acute stroke.

BACKGROUND AND PURPOSE: To assess patient radiation exposure in comprehensive stroke imaging using multidetector row CT (MDCT) combining standard CT of the head, cerebral perfusion (CTP), and CT angiography (CTA) studies. METHODS: Examination protocols for CT and CTA of cerebral and cervical vessels, as well as CTP were simulated using a Somatom Sensation Cardiac 64. Effective doses were derived from measurements with the use of lithium-fluoride thermoluminescent dosimeters (LiF-TLD) at several organ sites using an Alderson-Rando phantom. RESULTS: LiF-TLD measurements resulted in effective doses of 1.7 mSv for CT, 1.9 mSv for CTA of intracranial vessels, and 2.8 mSv for CTA of cervical vessels, respectively. Depending on examination parameters, effective doses varied between 1.1 and 5.0 mSv for cerebral CTP. For CTP, local doses in the area of the primary beam ranged between 114 and 444 mGy. CONCLUSIONS: Comprehensive stroke imaging may result in up to 9.5 mSv with possible local doses of 490 mGy. Although critical doses for organ damage (eg, cataract formation or hair loss) are not reached, physicians need to be aware of possible radiation induced sequelae particularly in repetitive examinations.

Acute Disease↗
PubMed2006

Renovascular disease: a review of diagnostic and therapeutic procedures.

The clinical importance of renovascular disease, atherosclerotic or of other origin, arises from the fact, that renal artery stenosis (RAS), if hemodynamically significant (> 70% diameter reduction), induces arterial hypertension, renal insufficiency or both. The prevalence of RAS rises with increasing age and with the presence of atherosclerosis of the aorta, carotid, coronary and peripheral arteries. Typical clinical symptoms, as uncontrolled hypertension or renal dysfunction in the absence of pathological urinary findings, are helpful to select patients for further screening methods: We see a prominent role of color duplex sonography as a screening procedure. Intra-arterial angiography remains gold standard for the diagnosis of RAS. The major problem in daily clinical practice is the differentiation between patients in which hypertension and kidney function can be improved or normalized by removal of RAS and those with ''fixed'' hypertension and irreversible kidney dysfunction and therefore to decide if it is worth while to perform invasive treatment as angioplasty or surgery. In this setting, the proof of hemodynamic significance is essential and is indicated especially when the stenosis has a diameter reduction of < 50-70% only. Methods proving a critical stenosis are intra-arterial measurement of the pressure gradient, measurement of differential renal vein renin and duplex sonography. In addition, predictors of treatment outcome should be considered. Studies analyzing if patients improve with blood pressure and kidney function after removal of RAS have shown that high grade stenosis and/or very high blood pressure indicate a good outcome. Further prognostic factors are the absence of parenchymal disease and/or positive functional test. In the presence of a critical stenosis in a patient with a clear clinical problem with hypertension and/or renal dysfunction a positive effect of invasive treatment seems warranted despite the risks that must be considered as well in angioplasty as in surgery. The selection for the type of invasive treatment requires a clarification of the treatment goals in the individual patient, the evaluation of the morphology and localization of the stenosis as the presence of other vascular disease (aortic aneurysm, peripheral artery disease etc.) and the assessment of the risk according to the type of intervention.

Decision Trees↗
PubMed2005

[Transjugular intrahepatic portosystemic stent shunt: indications and long-term outcome].

The transjugular intrahepatic portosystemic stent shunt has replaced surgical shunt procedures as the standard therapy for complications of portal hypertension such as refractory ascites and recurrent variceal bleeding. However, reinterventions due to TIPS stenosis are necessary in 25-50 %. Major complications are the manifestation or worsening of hepatic encephalopathy. Recent studies using PTFE covered stents have shown lower stenosis rates and a trend towards prolonged survival.

Ascites↗
PubMed2005

[Assessment of two different software solutions for the evaluation of CT colonography].

PURPOSE: To compare a commercial CT colonography software ("Colonography", Siemens, Forchheim) with a non-commercial post-processing system ("Colotux", Department of Informatics). MATERIAL AND METHODS: Identical data sets of 10 patients, who underwent an ultra-low-dose multi-detector CT colonography (ULD-MDCTC) (4x1 mm collimation, 8 mm pitch, 120 kVp, 10 mAs) were analyzed retrospectively. Assessment was performed using both software solutions by two resident radiologists, who did not have any experience with any colonography software tool before and who did not know the clinical symptoms of the patients or the results of the conventional colonoscopy. Both systems were analyzed using several subjective quality criteria including workflow, handling, image quality, endoluminal navigation and analysis of lesions with grading on a 5-point-scale. Results concerning polyps were compared between the two systems as well as with conventional colonoscopy. RESULTS: Both colonography systems detected the same number of polyps. Although both showed some advantages for single criteria, no relevant difference was noted in general for subjective assessment. The time for calculation of three dimensional interactive volumes was three times longer for "Colotux" compared to "Colonography." Linux-based "Colotux" showed a trend towards better subjective image quality and easier measurement of polyp size. An intuitive desktop and "Syngo"-workflow integration were advantages of "Colonography." CONCLUSION: The analysis of CT colonographies (4-detector-row-CT-scanner, ultra low dose technique, supine position) can adequately be achieved by both software solutions. There was no significant subjective or objective difference of quality between a "stand-alone" individual system and a commercial workflow-integrated solution. A relevant factor for decision between the two systems may be the difference in time needed for the 3D volume calculation, especially in institutes with a high frequency of examinations.

Aged↗
PubMed2005

[Effective didactic skills training for teachers in continuing medical education].

PURPOSE: To develop, test, evaluate and implement effective state-of-the-art teacher training in didactic skills and methods. The training concept should be designed and beneficial for medical teachers' postgraduate medical education (CME). MATERIALS AND METHODS: A 5-day workshop with 12 theoretical and 9 "hands-on" modules was designed and stepwise improved, according to the trainees' feedback. All trainees were trained in small groups (6 to 10 participants per workshop). The workshops consisted of mini-lectures, repeated micro teaching exercises and video-supported feedback concerning the following key-competencies: Communication of goals; methods to trigger interactivity; design of slides in power point presentations; effective feedback-techniques; and use of media, time-management, skills teaching, assessment methods (e. g. OSCE and others), evaluation and general presentation skills. The evaluation was based on two components: A) trainees' scores in two objective structured teaching exercises (OSTEs) at the beginning and end of workshop, with the ratings of 15 to 20 external observers checked for significant trends (Pearson's X2 test) in 17 given criteria for high teaching effectiveness; B) the trainees rated 20 teaching competencies in a retrospective "pre-post-analysis" (self-assessment questionnaire) at the end of each workshop and after 6 to 12 months later. RESULTS: The results revealed highly significant (p < 0.01) improvements in 13 of 16 OSTE-criteria and in 12 of 13 items of the pre-post-analysis, predominantly estimated to be "persistent." Overall, trainees; feedback has been highly encouraging to continue and broaden the program. The discussion covers potential factors for the training success as well as pitfalls and the controversial issue of fees. CONCLUSION: The designed 5-day training workshops to enhance didactic skills and teaching methods turned out to be highly effective and can be attended by all medical teachers with different teaching backgrounds and specialties. The training has been certified for CME-credits by the Academy of the Physicians' State Association of North Rhine-Westphalia.

Certification↗
PubMed2005

[Differential diagnosis of focal liver lesions using contrast-enhanced MRI with SHU 555 A in comparison with unenhanced MRI and multidetector spiral-CT].

PURPOSE: To evaluate the ability of contrast-enhanced MRI with SHU 555 A to provide additional information for characterization of focal liver tumors compared with non-enhanced MRI and multislice spiral CT. MATERIALS AND METHODS: In a prospective manner the images of 45 patients who underwent multislice spiral CT, unenhanced MRI alone and unenhanced and SHU 555 A-enhanced MRI including dynamic imaging at a field strength of 1.0 T were analyzed in a blinded reading. The readers had to determine on a scale from 1 to 5 whether a tumor was benign or malignant. Furthermore, the readers had to give a definitive diagnosis for each lesion. A true cut needle biopsy served as gold standard against which all imaging procedures were compared. RESULTS: The sensitivity for differentiation malignant vs. benign lesion was 77 % with spiral CT, 72 % with unenhanced MRI and 94 % with SHU 555 A-enhanced MRI, respectively (p < 0.05). The specificity for spiral CT was 73 %, for unenhanced MRI 83 % and for contrast-enhanced MRI 83 %, respectively (n. s.). Compared with the histopathologic results, the correct diagnosis was made with spiral CT in 25/45 (56 %), unenhanced MRI in 16/45 (36 %) and contrast-enhanced MRI in 32/45 (71 %) of the patients (p < 0.05). For the subgroup of patients with liver cirrhosis, the correct diagnosis was established with spiral CT in 16/23 (70 %), unenhanced MRI in 9/23 (39 %) and contrast-enhanced MRI in 19/23 (83 %) of the patients (p < 0.05). CONCLUSION: Contrast-enhanced MRI with SHU 555 A has the ability to improve the differential diagnosis of focal liver tumors compared with unenhanced MRI and multislice spiral CT.

Biopsy, Needle↗
PubMed2004

[Pain management in non-juvenile, aseptic osteonecrosis].

BACKGROUND: Adult aseptic osteonecrosis (ON) represents a clinical picture with unexplained etiology. Since curative treatment of this disease often succeeds only in the early stage, pain therapy plays an important role in the treatment process. METHOD: We compared established and novel treatment options for ON as well as our own results after i.v. administration of the prostacyclin analogue iloprost with corresponding studies in the literature. RESULTS: In addition to treatment with nonsteroidal antirheumatic agents and opioids, surgical "core decompression," vasoactive medications, and hyperbaric oxygenation are effective. Treatment with iloprost for 5 days resulted in highly significant pain reduction. CONCLUSION: Symptomatic treatment is indicated in all stages of ON and curative treatment in stage I and early stage II. In cases of disease progression in the large joints, early endoprosthetic replacement is indicated to avoid secondary damage. In addition to employing vasoactive substances, a further curative treatment approach could be the use of mesenchymal stem cells.

Adult↗
PubMed2004

Thalidomide for the treatment of idiopathic myelofibrosis.

Except rare instances of allogeneic stem cell transplantation, treatment of idiopathic myelofibrosis (IMF) is only palliative and based on cytostatic treatment (hydroxyurea and anagrelide), androgen therapy, steroids and splenectomy. Thalidomide is an anti-angiogenic and immunomodulatory drug with a wide spectrum of activities, which are not clearly understood. Current data suggest that the action of thalidomide is related to several different mechanisms, including suppression of tumor necrosis factor, effects on basic fibroblast growth factor, vascular endothelial growth factor, interleukins and interferons, downregulation of selected cell surface adhesion molecules, and changes in the lymphocyte subsets. We administered thalidomide to 16 patients with IMF (15 men, one women) who had transfusion-dependent anemia, thrombocytopenia or symptomatic splenomegaly. Median age was 59 yr (range: 52-78). Patients received thalidomide at an escalating dose from 100 to 400 mg/d (median 300 mg). The drug was discontinued in four patients because of progressive disease (two) or polyneuropathy (two). Other adverse effects were obstipation (10), fatigue (eight) and edema (two). Clinical response has now been observed for a median duration of 9 months (range: 3-20). Fifteen patients are evaluable. Anemia improved in six of 10 patients who were anemic. Platelet counts improved in five of seven patients with thrombocytopenia. Splenomegaly regressed in three of 13 patients. Lactate dehydrogenase (LDH) decreased in seven of 12 patients, but increased in four patients. LDH levels were not correlated with clinical response. In summary, thalidomide appears useful in the treatment of IMF.

Aged↗
PubMed2004

Prediction of relapse after antithyroid drug therapy of Graves' disease: value of color Doppler sonography.

Opinions differ regarding the indications for antithyroid drugs, radioiodine and surgery in patients with Graves' disease because the likelihood of long-term remission after medical treatment cannot be predicted. The aim of this study was to assess the value of quantifying thyroid blood flow in an attempt to predict outcome following withdrawal of antithyroid drug therapy. Spectral Doppler recordings were obtained from the thyroid arteries in 24 patients with Graves' disease at the time of diagnosis. Thyroid blood flow levels measured at the time of diagnosis of Graves' disease were correlated with outcome following withdrawal of medical treatment (mean duration of treatment: 14 months). Clinical follow-up for at least 18 months (range: 18 - 39 months) after antithyroid drug withdrawal was possible in 13 patients (12 women). Mean peak systolic velocity and volume flow rate values as well as thyroid volume measured at the time of diagnosis were significantly higher (139 cm/s, SD 46; 195 ml/min, SD 170; 52 ml, SD 18) in patients who relapsed after drug treatment compared with patients in remission (71 cm/s, SD 27; 67 ml/min, SD 61; 25 ml, SD 13). The correlation between thyroid blood flow measurements and thyroid volume was high (r = 0.79 - 0.96). Recurrence of disease could be predicted with a sensitivity of 71 % and a specificity of 100 % based on thyroid blood flow measurements. This preliminary data suggest that quantification of thyroid blood flow by means of Doppler sonography might be a useful tool to predict the outcome of Graves' disease following withdrawal of medical treatment and could be helpful in finding the adequate kind of therapy.

Adult↗