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W Heindel

Publications and source records attributed to W Heindel.

At least 109 records · Page 6Linked to original sources
PubMed1998

[Volume selective 31P NMR spectroscopy for differentiation of graph rejection and acute tubular necrosis after kidney transplantation].

Volume-selective 31P-MR spectra were obtained from 37 patients using a whole-body MR scanner in combination with surface coils and a modified ISIS sequence. The quantitative evaluation took place by line fitting to the signal in the time domain using a non-linear procedure. The following signal intensities were determined: PME, PDE, Pi, gamma-, alpha-, beta-ATP and pH. 1024 excitations were averaged to achieve an adequate signal-to-noise ratio (10.0 +/- 3.3), measurements lasting 34 minutes on average. The mean measured volume was 174 +/- 52.4 ml. Contamination by muscle tissue could be excluded based on the absence of phosphocreatinine signal in the spectra. Contamination by fatty tissue was excluded by visualisation. A reduction in the value of the Pi/alpha-ATP ratio as a function of time was observed due to the regeneration process following reperfusion injury. In transplant rejection (n = 7) a significant rise in Pi/alpha-ATP ratio was seen compared to the control group (n = 20) (0.4 +/- 0.16 vs. 0.22 +/- 0.11, p < 0.01), the calculated difference in pH was significant as well. In cases of acute tubular necrosis a reduced value fore the PME/PDE ratio was observed (0.65 +/- 0.1 vs. 0.96 +/- 0.5, p < 0.04). Acute tubular necrosis could be differentiated from rejection by difference in pH (6.93 +/- 0.1 vs. 7.14 +/- 0.19, p < 0.04).

Adenosine Triphosphate↗
PubMed1998

[Interventional palliative therapy].

From diagnostic procedures interventional radiology has developed a large number of therapeutic methods that have found a place in the treatment of palliative care patients. Minimal invasiveness and high efficiency characterise the implantation of metallic stents in the treatment of malignant biliary or esophageal obstruction and vena cava compression syndrome. Transcatheter arterial embolisation, chemoembolisation and chemoinfusion for palliative treatment of inoperable liver malignomas are performed at many centers. A specific concept and an accepted spectrum of indications have to be better defined by prospective trials. Therapeutic decisions in this patient group have to based on the individual case. The interventional radiologists is increasingly involved in the interdisciplinary decision making process.

Bile Duct Neoplasms↗
PubMed1997

Late results after resection of benign hepatic tumors: clinical and radiological findings.

The purpose of our work was to provide data on the recurrence of resected benign hepatic lesions and to evaluate the value of follow-up examinations in this group of patients. From August to October 1993, 75 patients who had been admitted for liver surgery for benign tumors between 1975 and 1993 were controlled by physical examinations, serological tests, US, and, in the case of equivocal US findings, by CT. The histological diagnoses of the operative specimen included hydatidosis in 43 patients, focal nodular hyperplasia (FNH) in 12 patients, liver cell adenoma in 8 patients, cavernous hemangioma in 8 patients, and congenital cyst in 4 patients. Hepatic scars were observed in 36 of the 75 patients. Four cases of intrahepatic recurrence and 1 case of intraperitoneal spread were observed in the 42 patients with recent hydatosis. Long-term postoperative controls (specific serological tests, US) are necessary in the management of patients with hydatid disease. Follow-up examinations are not indicated in asymptomatic patients who have been operated on for FNH, hemangioma, or congenital cysts.

Adult↗
PubMed1997

[31P-MR spectroscopy of the human liver--the spectral indications of lymphoma infiltration].

PURPOSE: To evaluate whether phosphorus magnetic resonance spectroscopy (31P-MRS) enables a non-invasive detection of liver involvement in systemic diseases like Hodgkin's lymphoma. MATERIALS AND METHODS: Using a clinical 1.5 Tesla whole-body MR system image-guided localised phosphorus MR spectra from the anatomically defined volumes of interests were measured. A combination of surface coil, adiabatic excitation pulse and modified image-selected in vivo spectroscopy (ISIS)-sequence was applied. The spectroscopy data were evaluated quantitatively with a time-domain fit programme using non-linear optimisation algorithms to quantify peak areas. After establishment of the examination protocol, 22 healthy volunteers and 13 patients with suspected lymphoma infiltration of the liver were examined. RESULTS: Liver spectra of patients suffering from lymphoma infiltration differed significantly from spectra of persons with normal liver: 1. The peak area ratio of phosphomonoesters (PME) to beta-NTP was elevated in all patients with histologically confirmed liver lymphoma. 2. Patients suffering from Hodgkin's disease with specific or unspecific liver infiltration (n = 7) could be differentiated from patients without liver involvement. In case of infiltrated liver, the peak area ratio PME to beta-NTP was increased, and the pH value was shifted to lower values. Unambiguous differentiation between non-specific (n = 3) and specific (n = 4) infiltration of the liver was not possible. 3. In patients after cytostatic treatment (n = 3), an increase of the peak area ratio of inorganic phosphate to beta-NTP was observed. CONCLUSIONS: Our preliminary results indicate that 31P-MRS can yield pointers to liver involvement in patients with systemic diseases such as Hodgkin's disease, which may be hardly detected by imaging methods.

Adolescent↗
PubMed1997

[Localization of puncture needles in MRI: experimental studies on precision using spin-echo sequences at 1.0 T].

PURPOSE: To evaluate accuracy of needle localisation using and signal enhancement on a 1.OT MR imager for various needles for MR-guided biopsy. METHODS: The differences between actual and virtual needle position of needles with different orientations were evaluated in a phantom for spin-echo including turbo-spin-echo sequences. RESULTS: Artifacts depended on the orientation of the needle relative to the field B0, frequency-encoding gradients (Gf) and slice orientation. This resulted in different artifact shapes and sizes for left or right and cranial or caudal biopsy access routes. Applying turbo spin echo sequences feasible for biopsy, the signal void of a 18 G needle (Cook) parallel to Gf reached between 0.3 and. 4.6 mm further into the medium than the real needle tip, depending on needle orientation relative to B0. The diameter of the signal void around the needle varied, the needle shaft was right in the centre of the signal void. With Gf orthogonal to the needle the offset of signal void to needle tip ranged from 2.7 to 3.3 mm, while the actual position of the needle shaft was up to 3.3 mm lateral of the signal void center. While nominal echo times did not influence the size of the artifact in turbo-spin-echo sequences, the artifacts increased with smaller matrix and larger water-fat shift. Material and mass of the needle determined the size of the artifacts as well. CONCLUSION: Localisation accuracy of the needle can be optimised by choosing optimal gradient directions depending on whether needle tip or shaft position should be displayed.

Artifacts↗
PubMed1997

CT and MR imaging in primary cerebral non-Hodgkin's lymphoma.

PURPOSE: To determine the morphological appearance and topographical distribution of primary cerebral non-Hodgkin's lymphoma (NHL). MATERIAL AND METHODS: CT and MR examinations of 68 patients with primary cerebral NHL were analyzed. The NHLs were classified by the Kiel classification and immunohistological data, as centroblastic (25), immunoblastic (24), lymphoblastic (5), Burkitt (1), non-subclassifiable type B (11), and T-cell lymphoma (2). RESULTS: Centroblastic lymphomas tended to predominate in the parietal lobe (56.5%) and the corpus callosum (59.1%) while immunoblastic lymphomas were mainly distributed in the frontal lobe (52.8%). About 2/3 of all NHLs showed a multifocal occurrence. Important for differential diagnosis, ventricular involvement was proved in 83.3% of these cases. In the remaining 26 patients with a solitary lymphoma, a periventricular location could be detected in only 8 cases. Central necroses were frequent in HIV-positive patients (7/11, 63.6%) but rare in the HIV-negative patients (9/57, 15.8%). On T2-weighted SE MR images, 8/11 centroblastic lymphomas gave a signal that was isointense with, or lower than, that of the contralateral white matter, while 8/10 immunoblastic lymphomas gave a higher signal. CONCLUSION: The radiological finding of multifocal brain lesions with ventricular involvement is relatively specific for primary cerebral NHL. However, subclassification on the basis of the CT or MR imaging results is not yet possible.

Adult↗
PubMed1997

Nontraumatic subarachnoid hemorrhage: value of repeat angiography.

PURPOSE: To evaluate the benefits and risks of repeat cerebral angiography in patients with subarachnoid hemorrhage of unknown cause. MATERIALS AND METHODS: Findings from 391 angiographic examinations (323 initial, 68 repeat) were retrospectively reviewed in 323 patients with nontraumatic subarachnoid hemorrhage to determine the cause of bleeding and the frequency of complications with neurologic deficit. RESULTS: At the initial angiographic examination, aneurysms were found in 195 patients (60.4%), and arteriovenous malformations were found in 11 patients (3.4%). Sixty-six patients with negative findings at initial examination underwent repeat cerebral angiography. Three additional aneurysms were detected, all of which could be seen retrospectively on the initial angiogram. In 63 patients, the cause of bleeding remained unexplained. Complications of the 391 angiographic examinations were definitive neurologic deficits in one patient (0.2%) and transient deficits in seven patients (1.8%). CONCLUSION: Repeat angiography is not necessary in patients with subarachnoid hemorrhage if technically good, carefully evaluated digital subtraction angiography was performed initially. Repeat angiography seems to be justified only when the initial examination is technically inadequate, when vasospasm is present, or if further bleeding occurs.

Adolescent↗
PubMed1997

[Injuries of the spine: current concepts in radiologic diagnosis].

This review discusses the usefulness of plain radiography, computed tomography (CT), and magnetic resonance imaging (MRI) in the evaluation of spinal trauma. The indications for the different imaging modalities in dependence on the specific pattern of injury are explored. Plain radiography still remains the prime method in the diagnosis of acute spinal trauma but there are substantial deficits, especially in the evaluation of the occipitocervical and the cervicothoracic junction as well as in the evaluation of the integrity of the posterior vertebral body line. If injury in these regions is suspected CT should follow plain radiography immediately. In the case of spinal trauma with unexplained neurologic deficits MRI is the method of choice for the detection of spinal cord injury. Recommendations with regard to instability and the classification of specific injuries, including examples of typical findings are presented.

Cervical Vertebrae↗
PubMed1996

A gene for autosomal dominant paroxysmal choreoathetosis/spasticity (CSE) maps to the vicinity of a potassium channel gene cluster on chromosome 1p, probably within 2 cM between D1S443 and D1S197.

Paroxysmal choreoathetosis/episodic ataxia is a heterogeneous neurological syndrome usually inherited in an autosomal dominant manner. Recently, the association of one form of episodic ataxia (defined by the presence of additional myokymia) with point mutations in the potassium channel gene KCNA1 was described. This gene locus on chromosome 12p (HGMW-approved symbol CSE) was excluded in a large pedigree with paroxysmal choreoathetosis and additional spasticity. Linkage to chromosome 1p where a cluster of related potassium channel genes is located, was demonstrated. Genotyping of 18 affected and 11 unaffected family members with 28 microsatellites over a region of 45 cM proved linkage with a lod score of 7.2 at a recombination fraction theta = 0 to D1S451/421/447/GGAT4C11. Crossing-over events in 9 patients and 4 unaffected offspring suggested a probable assignment of the gene to a region of 2 cM between D1S443 and D1S197.

Athetosis↗
PubMed1996

Iodixanol vs iopamidol in intravenous DSA of the abdominal aorta and lower extremity arteries: a comparative phase-III trial.

Iodixanol (Visipaque, 320 mgI/ml) was compared with iopamidol (Solutrast, 370 mgI/ml) in a double-blind, randomized, parallel group, intravenous DSA phase-III trial for evaluation of safety and efficacy. A total of 117 patients received iodixanol (n = 60) or iopamidol (n = 57). Diagnostic efficacy was evaluated using categoric and visual analogue scales. Discomfort and adverse events were recorded. A total of 39 patients collected urine up to 72 h after the examination for analysis. Diagnostic efficacy and radiographic density were similar in both groups. Discomfort was milder with iodixanol. The difference between the frequency of adverse events between both groups (iodixanol = 7, iopamidol = 2) was without statistical significance. Creatinine clearance was slightly more affected by iodixanol, whereas the increase in renal excretion of N-acetyl-beta-glucosaminidase (NAG) in the first 24-h collection period after the examination was significantly higher (p < 0.01) with iopamidol. Iodixanol was of equal diagnostic efficacy compared with iopamidol despite its reduced iodine content. Both contrast media are well suited for IV DSA.

Acetylglucosaminidase↗
PubMed1996

Pharmacokinetics of intraarterial mitomycin C in the chemoembolisation treatment of liver metastases.

1. The pharmacokinetics of mitomycin C (MMC) were investigated in 12 colorectal cancer patients with liver metastases undergoing chemoembolisation. Hepatic artery branches were embolized using polyvinylalcohol microspheres (150-250 microns) before applying 20 mg MMC in 4-8 min. 2. Serum MMC concentrations were determined from peripheral venous blood samples by reverse-phase HPLC using ultraviolet detection. Pharmacokinetic parameters were computed assuming an open two-compartment model. 3. Pharmacokinetic parameters were similar to values given in the literature for intravenous (IV) or intraarterial (IA) bolus MMC injections (Tmax = 7.0 min following the beginning of MMC infusion, Vss = 0.57 1/kg, C1 = 8.9 ml/min.kg, T1/2 alpha = 8.3 min, T1/2 beta = 58.6 min). 4. The area under the serum concentration-time-curve (AUC), standardized by the MMC amount injected, was similar to values reported in the literature for IV or IA bolus injections. There is no evidence for reduced systemic MMC exposure following the embolization procedure used.

Antibiotics, Antineoplastic↗
PubMed1996

The prevalence of lung cancer in vascular surgery patients.

Inhalative cigarette smoking is a major risk factor for atherosclerotic disease as well as primary carcinoma of the lung. On that account, this study was performed to determine the prevalence of primary lung cancer on admission in patients scheduled for vascular surgery. All patients presenting to our department for an intervention are screened for lung diseases. If this pretherapeutic examination suggests the existence of a lung tumor further diagnostic procedures are performed. Making use of a prospective computer-assisted patient-documentation system, we analysed incidental findings of lung cancer in those patients admitted for elective surgery. Between Jan. 1st 1990 and October 31st 1994, we electively treated 2214 patients with the diagnosis of vascular stenosis (n = 1711/77.3%) or atherosclerotic aneurysms (n = 503/22.7%) in our department. In 16 of these patients (m:f = 13:3; age 50-72 [mean: 61.1] years) a carcinoma of the lung was detected during preoperative diagnostic procedures, a prevalence of 0.72%. All these patients were smokers, with a daily inhalative nicotine consumption averaging 25 cigarettes per day for a mean of 35 years. 8 patients underwent a surgical (n = 6) or other invasive (n = 2) vascular interventions. In 8 patients no vascular intervention was performed because of the revealed lung carcinoma. The prevalence of lung cancer in a population of vascular patients in the present study is in accord with data of older investigations of high-risk groups. Only 2 out of 16 lung cancers were detected at a prognostically favourable stage. Smokers with symptoms of vascular disease should be carefully examined for signs of lung cancer.

Aged↗
PubMed1996

[A prospective study to assess the need for requested radiological studies].

PURPOSE: What is the percentage of non-indicated examinations in the routine work of a radiologic university clinic? METHODS: From April 1st, 1994, to June 30th, 1994, all examinations carried out in the Radiology Department of the University Hospital of Cologne, Germany, were evaluated prospectively by the radiological medical staff using a questionnaire. The question was whether the examinations were medically indicated or not. Requests for examinations which were not carried out due to lacking indications were excluded from evaluation. The percentage of error was assessed by analysis of random samples assigned to the referring clinicians. RESULTS: 1400 (5.4%) of a total of 25718 examinations were considered by the radiological medical staff as "not indicated". A subsample analysis performed for validation gave an upper margin of a 95% confidence interval of about 13% for this rating. The percentage of non-indicated examinations was higher in conventional x-ray examinations and ultrasonography than in x-ray angiography, computed tomography and magnetic resonance tomography. Examinations during night time and weekend showed a higher percentage of lacking medical indications than examinations during daytime. CONCLUSIONS: Considering a university clinic concerned with educational work, the percentage of radiological examinations carried out without medical indication was tolerable. However, indications must be further improved by intensifying the communication with the referring clinicians and by elaborating a higher standard of radiological and clinical postgraduate training.

Diagnostic Tests, Routine↗
PubMed1996

[The radiological findings in surgically and conservatively treated intracranial arachnoid cysts].

PURPOSE: To determine which appearances on CT or MRI are indications for surgical treatment of intracranial arachnoid cysts. METHOD: The images obtained from 26 patients treated either by surgery or conservatively were compared retrospectively. The features evaluated were the size of the cyst, evidence of a space-occupying lesion, cerebral abnormalities near the cyst and skull deformities. RESULTS: In 6 patients (23%), surgical treatment was indicated because of the presence of obstructive hydrocephalus. The presence of all other radiological findings did not differ significantly between the two analysed groups. 92% of the patients treated surgically benefited from the treatment. Fenestration and shunting produced similar results in respect to reduction in size of the cyst and the clinical and neurological symptoms. CONCLUSION: The only indication for surgery is the presence of obstructive hydrocephalus. The other features were seen equally amongst the patients treated conservatively and the surgical patients and had no influence on the decision to operate.

Adolescent↗
PubMed1996

[The MR tomographic diagnosis of intra- and paraspinal abscesses].

PURPOSE: Analysis of the MRT signals and their extent from intra- and paraspinal abscesses with reference to predisposing factors, their causes and localisation. PATIENTS AND METHODS: The histories and MRT findings in 34 Patients with intra- and paraspinal abscesses were evaluated retrospectively. Most of the patients (24/34) were older than 50 years. A second peak was below 30 years. RESULTS: 27/34 patients had some underlying disease which predisposed to infection, e.g., diabetes mellitus. The most common causal organisms were Staph. aureus (53%) and streptococci (15%). In 23/34 cases (68%), the abscesses were in the thoraco-lumbar or lumbar region, while only 6/34 occurred in the upper two-thirds of the thoracic spine and only 5/34 in the cervical region. In only 8/34 was the abscess confined to two vertebral lengths; in the remaining patients it was much more extensive. Intraspinal abscesses were about twice as large as the vertebral components and 1.5 times greater than paravertebral abscesses. The age of the abscesses could be estimated approximately from the signals. CONCLUSIONS: Contrast enhanced MRT permits detailed analysis of the compartments and exact estimation of the extent of the lesions and permits accurate monitoring of treatment.

Abscess↗