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Volkmar Nicolas

Publications and source records attributed to Volkmar Nicolas.

15 recordsLinked to original sources
PubMed2006

Detection of a double right coronary artery with 16-row multidetector computed tomography.

We present the case of a 46-year-old male patient with known history of coronary artery disease and recurrent episodes of angina pectoris. Coronary angiography revealed two vessels originating from the right coronary sinus. However, a clear distinction between a double RCA and a high take off of a large right ventricular branch could not be made. Contrast-enhanced MDCT was performed on a 16-row scanner which clearly depicted cardiac anatomy and finally established the diagnosis of a double RCA. To our knowledge, this is the first report of a true double RCA diagnosed by MDCT.

Coronary Angiography↗
PubMed2006

Patterns of cortical reorganization parallel impaired tactile discrimination and pain intensity in complex regional pain syndrome.

In the complex regional pain syndrome (CRPS), several theories proposed the existence of pathophysiological mechanisms of central origin. Recent studies highlighted a smaller representation of the CRPS-affected hand on the primary somatosensory cortex (SI) during non-painful stimulation of the affected side. We addressed the question whether reorganizational changes can also be found in the secondary somatosensory cortex (SII). Moreover, we investigated whether cortical changes might be accompanied by perceptual changes within associated skin territories. Seventeen patients with CRPS of one upper limb without the presence of peripheral nerve injuries (type I) were subjected to functional magnetic resonance imaging (fMRI) during electrical stimulation of both index fingers (IFs) in order to assess hemodynamic signals of the IF representation in SI and SII. As a marker of tactile perception, we tested 2-point discrimination thresholds on the tip of both IFs. Cortical signals within SI and SII were significantly reduced contralateral to the CRPS-affected IF as compared to the ipsilateral side and to the representation of age- and sex-matched healthy controls. In parallel, discrimination thresholds of the CRPS-affected IF were significantly higher, giving rise to an impairment of tactile perception within the corresponding skin territory. Mean sustained, but not current pain levels were correlated with the amount of sensory impairment and the reduction in signal strength. We conclude that patterns of cortical reorganization in SI and SII seem to parallel impaired tactile discrimination. Furthermore, the amount of reorganization and tactile impairment appeared to be linked to characteristics of CRPS pain.

Adult↗
PubMed2006

Transbronchial biopsy guided by low-dose MDCT: a new approach for assessment of solitary pulmonary nodules.

OBJECTIVE: The objective of our study was to determine whether transbronchial bronchoscopic biopsy of solitary pulmonary nodules under CT guidance using a low-dose protocol can increase diagnostic yield in patients who had undergone unsuccessful conventional bronchoscopic biopsy. SUBJECTS AND METHODS: We included 33 consecutive patients (25 men; mean age +/- SD, 64 +/- 9.6 years) with solitary pulmonary nodules at different sites and with a lesion-to-pleura distance of at least 2 cm who previously underwent conventional bronchoscopy that did not result in histologic diagnosis. All patients were prospectively investigated with transbronchial bronchoscopic biopsy under MDCT guidance. Examinations were performed with the patient in conscious sedation using a low-dose protocol (80 kV, 20 mAs, 5-mm collimation, 10-mm slices). The position of the tip of the biopsy device was confirmed and documented before biopsies were performed. All specimens were examined by standard histopathologic techniques. The effective radiation dose was calculated for every patient. RESULTS: The diagnostic yield was 24 in 33 selected patients (overall accuracy, 72.7%): 13 (54%) had primary lung cancer and 11 (46%) had benign diagnoses. The formal operative characteristics were sensitivity, 59%; specificity, 100%; positive predictive value, 100%; and negative predictive value, 55%. The final diagnoses of the remaining nine patients in whom transbronchial bronchoscopic biopsy was not diagnostic were non-small cell lung cancer (n = 3); small cell lung cancer (n = 3); and alveolar carcinoma, carcinoid tumor, and hemorrhaged bulla (n = 1 each). All nonmalignant diagnoses were confirmed by 6 months radiographic and clinical follow-up. The mean duration of the procedure was 39 +/- 15 minutes, and the average effective dose was 0.7 mSv (range, 0.5-1.1 mSv). One case of pulmonary hemorrhage (3%) occurred after the procedure. CONCLUSION: MDCT-guided transbronchial bronchoscopic biopsy is a promising and safe tool for the diagnostic pathway of solitary pulmonary nodules in previously undiagnosed patients. Image quality was sufficient with low-dose protocols, which resulted in low radiation exposure for patients and personnel.

Biopsy, Needle↗
PubMed2005

Evaluation of chronic infectious interstitial pulmonary disease in children by low-dose CT-guided transthoracic lung biopsy.

BACKGROUND: Children with chronic infectious interstitial lung disease often have to undergo open lung biopsy to establish a final diagnosis. Open lung biopsy is an invasive procedure with major potential complications. Transthoracic lung biopsy (TLB) guided by computed tomography (CT) is a less-invasive well-established procedure in adults. OBJECTIVE: Detailing the role of low-dose CT-guided TLB in the enhanced diagnosis of chronic lung diseases related to infection in children. MATERIALS AND METHODS: A group of 11 children (age 8 months to 16 years) underwent CT-guided TLB with a 20-gauge biopsy device. All investigations were done under general anaesthesia on a multidetector CT scanner (SOMATOM Volume Zoom, Siemens, Erlangen, Germany) using a low-dose protocol (single slices, 120 kV, 20 mAs). Specimens were processed by histopathological, bacteriological, and virological techniques. RESULTS: All biopsies were performed without major complications; one child developed a small pneumothorax that resolved spontaneously. A diagnosis could be obtained in 10 of the 11 patients. Biopsy specimens revealed chronic interstitial alveolitis in ten patients. In five patients Chlamydia pneumoniae PCR was positive, in three Mycoplasma pneumoniae PCR was positive, and in two Cytomegalovirus PCR was positive. The average effective dose was 0.83 mSv. CONCLUSION: Low-dose CT-guided TLB can be a helpful tool in investigating chronic infectious inflammatory processes in children with minimal radiation exposure. It should be considered prior to any open surgical procedure performed for biopsy alone. In our patient group no significant complication occurred. A disadvantage of the method is that it does not allow smaller airways and vessels to be assessed.

Adolescent↗
PubMed2005

Sensorimotor retuning [corrected] in complex regional pain syndrome parallels pain reduction.

Patients with complex regional pain syndrome (CRPS) and intractable pain showed a shrinkage of cortical maps on primary (SI) and secondary somatosensory cortex (SII) contralateral to the affected limb. This was paralleled by an impairment of the two-point discrimination thresholds. Behavioral treatment over 1 to 6 months consisting of graded sensorimotor retuning led to a persistent decrease in pain intensity, which was accompanied by a restoration of the impaired tactile discrimination and regaining of cortical map size in contralateral SI and SII. This suggests that the reversal of tactile impairment and cortical reorganization in CRPS is associated with a decrease in pain.

Behavior Therapy↗
PubMed2005

Metastasis to skeletal muscle from esophageal adenocarcinoma.

We report on a case of a 54-year-old man who was admitted to hospital with diffuse muscular pain and recurrent vomiting. Diagnosis of an adenocarcinoma of the esophagus was established by endosonography-guided biopsy. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed multiple nodular lesions within the skeletal musculature; CT-guided biopsy proved the metastatic origin of the primary tumor site. The report stresses the importance of CT and MRI in patients with proven or suspected metastases to skeletal muscle and provides a short overview of the literature.

Adenocarcinoma↗
PubMed2004

Chest radiography for the diagnosis of acute aortic syndrome.

PURPOSE: We sought to assess the diagnostic accuracy of routine chest radiography for the acute aortic syndrome (dissection, intramural hematoma, penetrating ulcer, or nondissecting aneurysm). METHODS: During a 6-year period, 216 patients (143 men, 73 women; mean [+/- SD] age, 58 +/- 17 years) underwent chest radiography for suspected acute aortic syndrome. Chest films were re-evaluated blindly for aortic disease, based on an overall impression using standard criteria such as widening of the aortic contour and mediastinal shadow. Findings were matched to tomographic images, anatomical inspection, or both, as the criterion standard; aortic disease was confirmed in 109 (50%) of the patients. RESULTS: Chest radiography had a sensitivity of 64% (70/109) and a specificity of 86% (92/107) for aortic disease. Sensitivity was 67% (38/57) for overt aortic dissection, 61% (22/36) for nondissecting aneurysm, and 63% (10/16) for intramural hemorrhage or penetrating ulcer. However, sensitivity was lower for pathology confined to the proximal aorta (47% [21/45]) than for disease involving distal aortic segments (77% [49/64]). A receiver operating characteristic curve analysis of aortic diameters failed to identify a threshold for the diagnosis of aortic disease. CONCLUSION: Chest radiography is of limited value for diagnosing the acute aortic syndrome, particularly for conditions confined to the ascending aorta. Since a definitive diagnosis is required in any patient with clinically suspected acute aortic syndrome, routine chest radiography should be replaced by tomographic aortic imaging.

Acute Disease↗
PubMed2004

Evaluation of tracheobronchial anomalies in children using low-dose multidetector CT: report of a 13-year-old boy with a tracheal bronchus and recurrent pulmonary infections.

Tracheobronchial anomalies in children may be associated with recurrent episodes of pulmonary infections and symptoms of recurrent or persistent airway obstruction. Diagnosis by conventional imaging may be difficult. Multidetector computed tomography (MDCT) offers the possibility to generate a virtual three-dimensional bronchoscopy, thus enabling detailed overview of the tracheobronchial system. We report on a 13-year old boy, admitted to hospital after recurrent episodes of bronchial infections. Functional studies showed airway obstruction with no response to bronchodilators. A chest radiograph was normal. Flexible bronchoscopy revealed tracheobroncho malacia of the distal trachea and the right main bronchus. The ostium of an accessory right-sided tracheal bronchus, which could not be entered by the endoscope, was also detected. MDCT using a low-dose protocol was performed on a four-section scanner (Somatom Volume Zoom, Siemens, Erlangen, Germany). A three-dimensional virtual bronchoscopy based on surface rendering was generated, which confirmed moderate narrowing of the trachea and right main bronchus. Furthermore, an accessory and stenotic tracheal bronchus including poststenotic segments, ventilating parts of the right upper lobe, could be clearly visualized. MDCT can be a valuable instrument in the diagnostic pathway of assessing tracheobronchial anomalies in children, including visualization of poststenotic bronchial structures. The use of low-dose protocols provides adequate image quality to perform virtual bronchoscopy, thus reducing administered radiation to a tolerable amount.

Adolescent↗
PubMed2003

Functional imaging of perceptual learning in human primary and secondary somatosensory cortex.

Cellular mechanisms underlying synaptic plasticity are in line with the Hebbian concept. In contrast, data linking Hebbian learning to altered perception are rare. Combining functional magnetic resonance imaging with psychophysical tests, we studied cortical reorganization in primary and secondary somatosensory cortex (SI and SII) and the resulting changes of tactile perception before and after tactile coactivation, a simple type of Hebbian learning. Coactivation on the right index finger (IF) for 3 hr lowered its spatial discrimination threshold. In parallel, blood-oxygen level-dependent (BOLD) signals from the right IF representation in SI and SII enlarged. The individual threshold reduction was linearly correlated with the enlargement in SI, implying a close relation between altered discrimination and cortical reorganization. Controls consisting of a single-site stimulation did not affect thresholds and cortical maps. Accordingly, changes within distributed cortical networks based on Hebbian mechanisms alter the individual percept.

Adult↗
PubMed2003

Functional magnetic resonance imaging mirrors recovery of visual perception after repetitive tachistoscopic stimulation in patients with partial cortical blindness.

We investigated three patients with partial cortical blindness after brain injury by means of functional magnetic resonance imaging (fMRI) before and after the application of a daily visual stimulation-therapy over a period of 6 months. Before therapy, fMRI data showed a severely reduced blood-oxygen-level-dependent (BOLD) signal in primary visual cortex when compared to healthy volunteers. Following several months of rehabilitative therapy a neuropsychological improvement of visual functions was accompanied by an increase in BOLD signal of residual perilesional regions whereas fMRI data of the control group remained unchanged. A high capacity of functional recovery and synaptic plasticity of surviving perilesional neuronal structures of primary visual cortex followed by an increased input into post-connected visual areas can be discussed as a basis for the reoccurrence of visual functions.

Adult↗
PubMed2003

Lipomatous hypertrophy of the interatrial septum: a prospective study of incidence, imaging findings, and clinical symptoms.

BACKGROUND: Lipomatous hypertrophy of the interatrial septum (LHIS) is a benign disorder characterized by fat accumulation in the interatrial septum. It typically occurs in elderly, obese patients and may cause arrhythmia. OBJECTIVES: The purpose of this study was to determine the imaging features of this cardiac pathology using multislice CT (MSCT), and its relationship with clinical findings. MATERIALS AND METHODS: A total of 1,292 consecutive patients who underwent MSCT of the thorax from September 2001 to August 2002 were prospectively studied. Beside the analysis of patient records, the amount of fat in the interatrial septum, and its size and shape were determined. RESULTS: Among the 1,292 patients investigated, we found 28 (2.2%) with LHIS. The mean age of affected patients was 72.2 years. MSCT studies revealed a mass of fat attenuation with sharp margins and sparing of the fossa ovalis, resulting in a dumbbell shape in all patients. The median thickness of the interatrial septum was 32 mm (range, 20 to 62 mm), and the median craniocaudal extend was 62 mm (range, 51 to 89 mm). Twenty-one patients (75.0%) showed increased epicardial fat, 18 patients (64.3%) had significant pulmonary emphysema, and 13 of 21 patients (61.9%) showed ECG abnormalities. Three patients underwent functional cardiac MRI studies. In one patient, hemodynamic obstruction by LHIS was shown. CONCLUSIONS: MSCT scanning is a useful method to diagnose LHIS, a cardiac condition that in our series reached a 2.2% incidence. The lesion shows characteristic features, thus differentiating it from other cardiac tumors. Advanced age, obesity, pulmonary emphysema, and atrial arrhythmias are common additional findings in patients with LHIS.

Aged↗
PubMed2002

[Catecholamine-dependent hereditary Cushing's syndrome - follow-up after unilateral adrenalectomy].

CASE REPORT: We report on the laboratory, clinical, radiologic and histological findings of a 44-year-old male patient who was hospitalized with the clinical signs of Cushing's syndrome. The laboratory findings were suggestive of an adrenal genesis. Abdominal computed tomography revealed macronodular hyperplasia of both adrenal glands. Specific endocrinological tests demonstrated an increased secretion of cortisol during adrenergic stimulation which, however, was absent following beta-blocker medication. This would seem to point to an aberrant, beta-receptor-mediated regulation of cortisol secretion as being the cause of increased cortisol production. ACTH-independent bilateral macronodular adrenocortical hyperplasia was also noted in the patient's mother. Neither the father nor the brother were affected by the disease. Apart from one case of familial appearance involving mother and daughter previously reported in the literature, this is the second description of a familial appearance and the first case involving mother and son. The patient underwent a left-sided adrenalectomy. Quick postoperative normalization of S-cortisol day profile and excretion of free dU-cortisol were noted under supportive temporary blockade of beta-receptors. In the further course, meanwhile spanning 2 1/4 years, a low basal cortisol secretion of the right adrenal gland has been observed, together with a lack of suppressibility in the dexamethasone suppression test. CONCLUSION: In the presence of mild clinical signs of adrenocortical insufficiency, matutinal administration of 5 mg hydrocortisone has proven sufficient for the past 6 months to reestablish a physiologic S-cortisol day profile with morning peak.

Adrenal Cortex↗