[Aneurysma spurium of the ascending aorta with secondary perforation into the right ventricle].
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Aortic Aneurysm, Thoracic↗
Biomedical subjects
K Lackner
Publications and source records attributed to K Lackner.
Inadequacies of repeated radiological examinations in a university hospital.
PURPOSE: To establish why 16% of 1,045 patients undergoing abdominal and/or vascular surgery referred to the University Department of Radiology for a B-image sonogram reported that a US of the same regions of the body had been conducted during the previous 6 weeks without any changes in the clinical status. STATEMENT OF THE PROBLEM: Evaluation of the reasons for these superfluous examinations and analysis of the consequences that the US follow-up examinations implied for the patient. MATERIAL AND METHODS: One senior resident radiologist and one senior resident surgeon reviewed the medical records of the patients reporting previous examinations and examinations scheduled at the time of the questioning of the patients. RESULTS: One hundred and eight (63%) of the 171 medical records were available. Data on previous examinations mentioned in the report forms were incorrect in 14 cases (13%). Therefore, further evaluations were based on 94 patients. Ten (8%) out of 121 sonograms, 4 (10%) out of 40 CT and 2 (20%) out of 10 MR investigations documented in the medical records had not been mentioned by the patients. As many as 41 (75%) of the 55 preliminary sonograms performed by general practitioners and specialists in private practice were not documented in the medical records. Even though records existed of clinically plausible findings, 36 (84%) of the 43 preliminary US investigations performed by doctors in the University Hospital were repeated to verify the diagnosis without any further diagnostic benefit. CONCLUSION: A cross-speciality consensus over the diagnostic value of B-image sonography and management of the findings obtained is of paramount importance.
Abdomen↗
Stabilization of neoclassical tearing modes by an externally applied static helical field.
The effect of a static helical magnetic field on the nonlinear growth of the neoclassical tearing mode (NTM) is investigated. The NTM is found to be stabilized by an externally applied helical field of a different helicity if the field magnitude is sufficiently large, suggesting a very simple method for stabilizing the NTM. The mechanism responsible for this stabilization is the decreased fundamental harmonic pressure perturbation of the NTM in the presence of the helical field.
Journal Article↗
Simultaneous attainment of high electron and ion temperatures in discharges with internal transport barriers in ASDEX upgrade
Internal transport barriers have been demonstrated to exist also under conditions with T(e) approximately T(i) approximately 10 keV and predominant electron heating of the tokamak core region. Central electron cyclotron heating was added to neutral beam injection-heated ASDEX Upgrade discharges with a preexisting internal transport barrier, established through programmed current ramping leading to shear reversal. Compared to a reference internal transport barrier discharge without electron cyclotron resonance heating, the electron heat conductivity in the barrier region was found not to increase, in spite of a fivefold increase in electron heat flux, and also angular momentum and ion energy transport did not deteriorate.
Journal Article↗
Necessity of requested radiologic examinations: a prospective study (report on the data of 1994).
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Diagnostic Imaging↗
[The sacral perineural system--are there radiological criteria for an indication for surgery? First results and literature survey].
PURPOSE: To establish recommendations for diagnostic imaging of cystic lesions of the sacral region and to evaluate for potential predictors of therapeutic outcome. METHODS: Conventional imaging of the lumbar spine, conventional CT, myelography, post myelo-CT and MRI were performed in 7 symptomatic [corrected] patients. All patients underwent operative decompression and histological examination. The radiographic examinations were reevaluated retrospectively and correlated with the postoperative outcome. RESULTS: In one patient the differential diagnosis of a neurinoma could not be excluded with CT and CT-myelography alone. In all 7 patients MRI provided a definite diagnosis and a precise presentation of the cyst extension. A complete postoperative remission of symptoms was noticed in 4, a partial remission in three cases. The correlation of cyst extension, cyst shape, and the communication with the subarachnoid space did not provide predictive information concerning operative outcome. CONCLUSION: MR can be used as the sole imaging tool for demonstration of cystic lesions. Relevant disadvantages in comparison to myelography and myelo-CT were not evident. No imaging modality could predict the value of surgical intervention.
Decompression, Surgical↗
[Indications and rate of repeat studies in the color duplex department of a radiology university clinic].
PURPOSE: Who refers patients for a color duplex ultrasonography (CDUS) in the routine work of a radiological university department and how frequent are repeat examinations? MATERIAL AND METHODS: 1110 patients had at least one CDUS examination between 5/97 and 5/98. The specialities of the referring physicians/primary examiners and the inpatient or outpatient status of the patients were documented at the first consultation. Additionally the patients were asked by the medical staff, whether, how often, and by whom ultrasonographic, CT, or MR examinations of the same organ system had been carried out during the last 4 weeks without evidence of any clinical changes. RESULTS: 97% of the 1118 patients were referred by one of the university departments. The arterial system was exclusively investigated in 58% and the venous system in 29% of the cases. 81% of the 651 arterial examinations were requested by the Departments of Vascular/Cardiac Surgery and Radiology. 75 repeated ultrasonographic examinations were documented in 67 (6%) of the 1118 consultations. Repetitions were documented in 8% of the arterial and in 3% of the venous examinations. X-ray angiographies were already done or planned in 105 of the 625 arterial CDUS (16%). Ultrasonographic referrals with parallel phlebographies (1% of 320 venous indications) as well as parallel CT and MR examinations (1% of the 1118 consultations, respectively) were the exception. CONCLUSIONS: In the described setting, CDUS was mainly used to assess the arterial vascular system prior to vascular surgery and radiological interventions. Repeat ultrasonographies alone (6%) and parallel examinations altogether (14%) were observed less frequently than expected.
Adolescent↗
[Primary intracranial germinoma. Problems in determining the diagnosis exemplified by 4 cases].
Primary intracranial germinoma is a possible cause of "idiopathic" diabetes insipidus in childhood and adolescence. The histopathologic appearance can be similar to inflammation, and may delay the final diagnosis. Further diagnostic difficulties are demonstrated by the use of anamnestic and clinical data as well as diagnostic imaging findings in four children with histologically proven primary intracranial germinoma.
Adolescent↗
[MRI-controlled preoperative wire marking of uncertain breast lesions].
PURPOSE: Small suspicious breast lesions that are only visible at MR imaging were preoperatively marked with a hook wire under MR-guidance to allow the removal of the lesion with tissue-sparing surgery. METHOD: In all patients the suspicious lesions were marked preoperatively under MR guidance with a hook wire using a commercially available stereotactic device. Interventions were performed with MR guidance on a 1.0 T and on a 1.5 T system. RESULTS: In 19 patients 22 lesions were localized. One lesion was missed and removed in a second procedure. The mean duration for localization was 66 +/- 20 min (range 38-119 min). In two patients two lesions were localized. The mean deviation of the wire tip to the lesion was 2.0 +/- 2.6 mm. In this series, 6 of 22 lesions were malignant. The mean diameter of the lesion was 7.6 +/- 2.6 mm (range 3-14 mm). CONCLUSION: Suspicious breast lesions detectable only in MR imaging can be accurately localized with a hook wire preoperatively under MR control to remove the lesion with a tissue-saving surgery.
Adult↗
Fluor-18-fluorodeoxyglucose positron emission tomography (FDG-PET) in malignant melanoma. Diagnostic comparison with conventional imaging methods.
PURPOSE: To assess the diagnostic value of fluor-18-fluorodeoxyglucose positron emission tomography (FDG-PET) in screening for melanoma metastases. MATERIAL AND METHODS: The case records of 94 melanoma patients who had been examined by whole-body FDG-PET between 1995 and 1999 were evaluated retrospectively. Forty patients showed evidence of lymphogenous and 42 of hematogenous metastasis. The maximal interval between PET and the diagnostic procedure under comparison was 2 weeks. Confirmation of the findings was based on histology or the clinical or radiological course. RESULTS: In 24 patients, all diagnostic examinations including CT had been performed within 2 weeks from PET. In no case did PET change the staging. In 13 patients, PET agreed with morphological diagnosis in the number of metastatically invaded organs. This included 3 patients without metastases. The estimated number of organs invaded by metastases was higher with PET in 5 patients and higher with morphological imaging techniques in 6 patients. Among the PET findings with higher or equivocal counts of organs with metastases there were 2 confirmed false-positive findings. CONCLUSION: In a selected patient population, FDG-PET was found to be inferior to CT for diagnosing lung and liver metastases. The supplementary use of FDG-PET is not generally of value once metastasis has been established.
Abdomen↗
Non-invasive determination of metabolite concentrations in human transplanted kidney in vivo by 31P MR spectroscopy.
PURPOSE: To investigate concentrations of phosphorus-containing metabolites in human transplanted kidney in vivo by quantitative 31P MR spectroscopy (MRS) using surface coils and to compare the obtained values with previous data. MATERIAL AND METHODS: In 5 patients with well-functioning transplanted kidneys, 31P spectra were obtained with the three-dimensional localization image-selected in vivo spectroscopy technique applying a protocol for quantitative spectroscopy using surface coils. Relaxation corrected signal intensities determined by time domain fitting were used to derive absolute molar concentrations for phosphate-containing metabolites. RESULTS: Little or no phosphocreatine in all spectra verified the absence of muscle contamination, confirming proper volume localization. The mean concentrations in the transplanted kidneys were as follows: ATP 1.60 +/- 0.26 mmol/ 1, PDE 2.14 +/- 0.91 mmol/l, Pi 0.66 +/- 0.25 mmol/l, PME 2.32+ /- 0.50 mmol/l. These values are consistent with previously reported values determined by other techniques. CONCLUSION: The non-invasive determination of absolute metabolite concentrations in human kidney using MRS supplements the use of signal intensity ratios to detect pathologic changes in the energy metabolism of transplanted kidneys.
Adenosine Triphosphate↗
Late resolution of diffusion-weighted MRI changes in a patient with prolonged reversible ischemic neurological deficit after thrombolytic therapy.
BACKGROUND: Reduced apparent diffusion coefficients (ADCs) correlate with cerebral ischemia. The combination of ADC with techniques to measure cerebral perfusion may help to assess the effect of treatment. CASE DESCRIPTION: The authors describe a patient who experienced an acute stroke with hemianopia, consequently treated with intravenous recombinant tissue plasminogen activator. Positron emission tomographic imaging and MRI, including diffusion-weighted MRI, were performed during and shortly after treatment with recombinant tissue plasminogen activator and 34 to 35 hours later. Cerebral perfusion of the left occipital region was reduced to 74%. Diffusion-weighted MRI detected a territory of restricted water movement in the corresponding area. Further magnetic resonance sequences did not show any pathologies. In follow-up, positron emission tomography demonstrated reperfusion. The volume of diffusion and ADC abnormalities detected by MRI decreased markedly. A few hours later, the patient recovered completely. A third MRI examination 10 days later showed normal findings. CONCLUSIONS: In a patient with prolonged reversible ischemic neurological deficit, resolution of early diffusion changes corresponded to cerebral reperfusion and to the recovery of clinical symptoms.
Acute Disease↗
MRA in patients with cerebrovascular disease. Considerations of clinical effectiveness.
OBJECTIVE: To establish in which clinical contexts cerebral MR angiography (MRA) is routinely carried out in a neurological university department and to describe its clinical impact. MATERIAL AND METHODS: Medical records, reports of findings and documentation of imaging examinations carried out in all 69 patients referred to the Department of Radiology from the Department of Neurology between 1995 and 1998 for cerebral MRA were evaluated. The clinical impact of all imaging findings was assessed on the basis of the medical records. RESULTS: Circulatory disturbances in the vertebrobasilar arteries (n = 34) were the most frequent indication for investigation. MRA followed CT or duplex sonography in 66 of the 69 patients with a mean delay of 8 days. MRA was considered diagnostically inferior to conventional MR in 11 cases, comparable in 30 and superior in 25. Comparing MRA and duplex sonography, the corresponding figures were 12, 29 and 23. In retrospect, 56 MRAs were judged unnecessary. CONCLUSION: Controlled clinical studies on optimal use of MRA are needed to avoid wasting resources and to exploit the method's full diagnostic potential in appropriate cases.
Adult↗
Soluble thrombomodulin and endothelial dysfunction in early atherosclerosis.
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Arteriosclerosis↗
Placement of Palmaz stents in malignant duodenal stenosis through a cutaneous fistula.
This is the first report of palliative percutaneous treatment of a malignant duodenal stenosis due to cancer of the pancreatic head with Palmaz stents. A 65-year-old male with a malignant tumour of the pancreatic head developed an abscess with fistular communication to the cutis. In the subsequent course of the disease, tumour growth led to a severe duodenal stenosis. To dilate the tumorous stenosis, three Palmaz stents were introduced coaxially into the duodenum percutaneously, via the preexisting fistula. A technique to pass an almost 90 degrees kink is described. Symptomatic malignant duodenal stenosis was treated by insertion of three Palmaz stents. Due to their accurately controlled passive expansion at the level of the stenosis, and the resulting good adaptation to the individual anatomical situation, they were suitable for application in the duodenum.
Aged↗
MR imaging of the chest: mediastinum and chest wall.
This review presents the options and limitations of MRI in non-vascular diseases of the mediastinum and the chest wall. In numerous thoracic pathologies, MRI is a useful supplement to spiral CT. This imaging procedure also allows a contrast-media-free differentiation of solid tumors and vascular lesions (e. g., aortic aneurysms). The advantages of MRI over CT are particularly useful when multiplanar tumor imaging is required prior to surgery to establish the exact spatial relationship between tumor and the other mediastinal structures. Primary indications for MRI in diseases of the mediastinum and chest wall are therefore: (a) tumors of the posterior mediastinum for determining their position in relation to the neural foramina and the spinal canal; (b) chest wall tumors; (c) preoperative multiplanar imaging of primary mediastinal tumors; and (d) contraindications against CT exams with iodine contrast media.
Contrast Media↗
[Frequency of repeated examinations in the ultrasonographic section of a radiological university department].
PURPOSE: What is the percentage of repeat examinations in the ultrasonographic section of a radiological university department? METHODS: All 4116 patients, who were first examined in the sonographic section of the Radiologic Department of the University of Cologne from 5/97 to 5/98, were asked by the medical staff, whether, how often and by whom ultrasonographic, CT or MR examinations of the same organ system had been carried out during the last 4 weeks without evidence of clinical changes. The data were documented using a structured questionnaire. RESULTS: Sonographic repeated examinations documented in 443 (10.8%) of the 4116 consultations. The proportion of in- to outpatients with repeat examinations was 26.0% to 74.0%. Contrarily, the repeated ultrasonographies were done by practitioners in 62.3% and by the university staff in 33.2% (radiology 48.2%). With regard to the 4116 consultations, the abdomen (81.1%) was the organ system most often examined repeatedly. Computed tomographies were already done or planned in 305 of 4116 patients (7.4%) and MR-tomographies were already done or planned in 57 patients (1.4%). CONCLUSION: The rate of repeated ultrasonographic examinations in a radiological university hospital was 19.6%.
Abdomen↗
[The MR tomographic imaging of uncomplicated secondary fracture healing exemplified by the distal radius fracture].
PURPOSE: To investigate the normal sequential MR-pattern of uncomplicated fracture healing within the first 6 weeks. METHODS: In 8 patients with distal radius fracture, 4 by 4 with and without intraarticular fracture, MR examinations were performed 3-4 days after the onset of fracture and after 1, 2, 3, 4, 5 and 6 weeks using the following techniques: T1-weighted spin echo, T2-weighted spin echo, T2 proton density weighted, STIR (short inversion time inversion recovery), T2-weighted turbo spin-echo and fast field echo (FFE, gradient echo). Sequential examinations were analysed regarding 1) the appearance of fracture line, 2) development of bone marrow signal, and 3) signal changes in surrounding soft tissue. Maximum contrast of bone marrow and soft tissue was measured. RESULTS: The fracture line in bone marrow was best detectable in FFE- and T2-weighted spin ech images during the first week and in T2-weighted fast spin echo and proton density-weighted images from the 2nd to 4th week. Beginning in the 5th-6th week an increase of signal intensity in the fracture gap was typical in all sequences except for T1-weighted spin echo. The contrast maximum of bone marrow and soft tissue, best detectable in STIR- and T2-weighted spin echo images, occurred in the 1st-2nd week. CONCLUSIONS: MRI shows a typical time-depending pattern of the fracture line, surrounding bone marrow and soft tissue in normal fracture healing. The degree of injury influences the development of signal changes.
Adult↗