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Werner Lang

Publications and source records attributed to Werner Lang.

17 recordsLinked to original sources
PubMed2005

Contrast-enhanced MR angiography of peripheral arteries including pedal vessels at 1.0 T: feasibility study with dedicated peripheral angiography coil.

PURPOSE: To prospectively determine feasibility of contrast material-enhanced magnetic resonance (MR) angiography of the peripheral arteries from distal aorta to pedal arteries with a 1.0-T system and a dedicated phased-array coil. MATERIALS AND METHODS: Twenty-seven patients with peripheral arteriosclerotic occlusive disease underwent contrast-enhanced MR angiography with an automatic moving-table technique. In addition, lower-leg and pedal arteries were examined without table movement (hybrid technique). Two radiologists independently reviewed MR angiograms to assess image quality and grade stenosis in 13 segments per leg. Each was blinded to patients' clinical data. Twenty-five of the patients also underwent conventional angiography. Stenosis grade at conventional angiography was assessed by two radiologists in consensus. Interobserver variability for stenosis grade at MR angiography was calculated with Cohen kappa test. Specificity and sensitivity of MR angiography in detection of stenosis of more than 50% and occlusion were calculated for both observers. The study was approved by the local ethics committee. RESULTS: In 14 of the 27 patients, hybrid technique was superior to moving-table technique because there was less venous overlap (11 patients), fewer motion artifacts (one patient), or both (two patients). In nine patients, there was no difference between techniques; in four patients, moving-table technique was superior. Stenosis grade was analyzed in 698 segments with MR angiography and in 638 segments with both conventional and MR angiography. Kappa analysis of interobserver agreement with MR angiography yielded a score of 0.84. For the 638 segments evaluated with both conventional and MR angiography, observers 1 and 2 assigned same grade of stenosis with both modalities in 558 and 555 segments, respectively. Sensitivity for stenoses greater than 50% and occlusion was 94.4% and 91.1% for observers 1 and 2, respectively, and specificity was 90.6% and 91.3%. More distal runoff vessels were shown with MR angiography in seven cases and with conventional angiography in two cases. CONCLUSION: Contrast-enhanced MR angiography of the peripheral vessels with a 1.0-T system and dedicated peripheral angiography coil is feasible, and in some cases, it provides additional information compared with conventional angiography.

Aged↗
PubMed2005

Magnetic resonance angiography of the carotid arteries using three different techniques: accuracy compared with intraarterial x-ray angiography and endarterectomy specimens.

PURPOSE: To compare three different magnetic resonance angiography (MRA) techniques with x-ray angiography and endarterectomy specimens. MATERIALS AND METHODS: Twenty-one patients underwent x-ray angiography, three-dimensional time-of-flight (TOF) focusing on the carotid bifurcation, high-resolution (HR) contrast-enhanced (CE) MRA, and time-resolved CE MRA. Stenoses of internal carotid arteries were evaluated by three independent observers on identical projection of x-ray angiography and MRA. Maximum stenosis grades on MRA were assessed additionally and correlated with endarterectomy specimens in 12 cases. RESULTS: Sensitivity for the detection of severe stenoses was excellent (100%) for all MRA techniques, and specificity was superior for three-dimensional TOF (96.7%) compared with HR CE MRA (80.6%) and time-resolved CE MRA (83.9%). The correlation between x-ray angiography and MRA for all stenoses was slightly superior for three-dimensional TOF and HR CE MRA compared with the time-resolved technique (kappa = 0.87 and 0.86 vs. 0.84). The same trend was seen for the interobserver agreement and for the correlation with endarterectomy specimens. Eleven up to 17 stenoses (depending on the MRA technique) were graded higher using additional projections. CONCLUSION: Three-dimensional TOF MRA yielded even more accurate results than HR CE MRA in grading of stenoses near the carotid bifurcation. Therefore, a combination of both methods seems to be advantageous.

Aged↗
PubMed2005

Femoral vein occlusion and spontaneous collateral ectasia presenting as recurrent hernia of the groin: a case report.

Femoral vein occlusion is not a common complication even after repeated hernia repair. We describe a case of a 14-year-old boy with a visible and soft, yet irreducible, mass below the inguinal ligament after 3 previous inguinal hernia repairs and heart catheterization in infancy. Further examination showed dilated venous collaterals, bypassing an occluded common femoral vein via the testicular sheaths and across the pelvic floor. We discuss etiology, diagnostic pitfalls, therapeutic options, and possible future complications, with a literature review.

Adolescent↗
PubMed2005

Prediction of dilutional acidosis based on the revised classical dilution concept for bicarbonate.

Due to the controversy surrounding the term dilutional acidosis, the classical dilution concept for bicarbonate has been rigorously revised for the prediction of pH, actual bicarbonate concentration, and base excess. In the algorithms derived for buffer solutions, blood, and whole body (1-, 2-, and 3-fluid compartment), only bicarbonate is considered. On dilution at constant Pco(2), the final concentration of bicarbonate is the sum in terms of pH, due to the following processes: dilution, formation from chemical reaction with the nonbicarbonate buffers phosphate, hemoglobin, and plasma proteins, and transfer from erythrocytes and interstitial fluid to plasma. At constant Pco(2), the level of carbonic acid is held constant, whereas those of the buffer bases are reduced by dilution, resulting in acidosis. In mixed bicarbonate/phosphate buffer, the final concentration of HCO(3)(-) exceeds the diluted value due to additional buffering of H(2)CO(3) by HPO(4)(2-). For whole blood in vitro, pH, and actual bicarbonate concentration are predicted from dilution with 0.9% saline from initial Hb (100%) to infinite dilution (pure saline). The acidosis from dilution of plasma bicarbonate is mitigated by contributions from plasma proteins (<1 mmol/l) and from the erythrocytes ( approximately 5 mmol/l). Similarly, for whole body, the main contributions to combat primary dilutional acidosis in the range of hemodilution (relative Hb: 100-50%) are from the erythrocytes (1.2-2.2 mmol/l) and from the interstitial fluid (3.3-7.2 mmol/l). Perioperatively measured nonrespiratory acidosis is predictable if caused by hemodilution with fluids containing neither bicarbonate nor its precursors, irrespective of other electrolytes.

Acidosis↗
PubMed2004

Small change in capnography led to the detection of an intravascular thrombus.

This report highlights the importance of accurate interpretation of even small intraoperative capnography changes. In this case, an otherwise unexplained sudden small decrease in end-expiratory carbon dioxide tension (P(ET)CO2) led to the detection of a deep venous thrombus. During the surgery of a 34-year-old woman with a known carcinoma of the corpus uteri, who was scheduled for paraaortal lymphadenectomy, a sudden decrease in carbon dioxide tension occurred. In careful exploration of the surgical field to rule out a thromboembolic event, the surgeons noticed an induration of the right iliac vein. A consulting vascular surgeon exposed a right-sided, irregular, double-lumen, common iliac vein with a thrombus the tip of which floated in the inferior vena cava. Following complete thrombectomy, the procedure was accomplished without further adverse events.

Adult↗
PubMed2003

Relative value of normalized sonographic in vitro analysis of arteriosclerotic plaques of internal carotid artery.

BACKGROUND AND PURPOSE: A close correlation between B-mode sonography and the histopathology and surface structure of plaque is rarely seen in vivo with high-grade stenoses of the extracranial carotid artery. The goal of this study was to determine whether normalized gray scale analysis and surface analysis of the plaque are capable of characterizing the attributes correctly. METHODS: Optimized B-mode images of 107 carotid endarterectomy specimens were captured, and the gray scale median (GSM) was calculated. The specimens were classified histologically into 3 groups: (1) calcium-rich hard plaques, (2) lipid-rich soft plaques, and (3) combined plaques. The surfaces of the plaques were classified as smooth or rough on the basis of standardized reference samples. The endoluminal surface was digitally documented in vitro by videoendoscopy and again classified into the same categories. All stages of the investigation were performed by 2 observers at 2 different times. RESULTS: Evaluation of the GSM showed close interobserver and intraobserver correlation (P<0.01, R>0.8). However, there was only 46% agreement between the GSM and the histopathological findings. In both in vitro angioscopy (kappa=0.936, P<0.001) and sonographic evaluation (kappa=0.842, P<0.001), there was a high correlation between the observers with regard to the evaluable specimens. In 73%, agreement was observed between the sonographic image and angioscopy. CONCLUSIONS: Normalized gray scale analysis and evaluation of the plaque surface in an in vitro study make possible observer-independent evaluation. The composition of the plaque cannot be visualized with sufficient accuracy by sonographic GSM analysis. This also applies to the correlation between sonography and actual surface composition of the plaque.

Aged↗
PubMed2003

Peripheral vessels: MR angiography with dedicated phased-array coil with large-field-of-view adapter feasibility study.

At magnetic resonance (MR) angiography with conventional phased-array coils, visualization of the vascular tree from the infrarenal aorta to the pedal arch is not possible in most patients. For this purpose, the authors developed a dedicated adapter with a large field of view that allows coverage of a body length of approximately 1,380 mm. Among five patients with peripheral arteriosclerotic disease, four underwent both conventional angiography and MR angiography. One hundred fourteen vascular segments from the infrarenal aorta to the feet were evaluated. Agreement between findings at conventional angiography and those at MR angiography was 94.7% (108 of 114) for all segments (96.1% [25 of 26] in the abdomen or pelvis, 97.5% [39 of 40] in the thigh, and 91.7% [44 of 48] in the calf or foot).

Aged↗
PubMed2003

MR diagnosis of superficial femoral artery aneurysm, primarily misdiagnosed as soft tissue tumor. A case report.

We report a 84-year-old man with an aneurysm of the superficial femory artery (SFA). Primarily, after B-mode sonography soft tissue neoplasm was suspected and sectional MR imaging was performed for further diagnostics. Because of blood flow related ghost artifacts, sectional MR led to the diagnosis of an partially thrombosed aneurysm without angiography. Initially, the differential diagnosis of an SFA aneurysm, which is extremely rare, has not been considered. Soft tissue neoplasms may have a similar appearance to partially thrombosed aneurysms. This case demonstrate the importance to notice also artifacts in sectional MRI which can give important informations for correct diagnosis.

Aged↗
PubMed2003

Ultrasonographic analysis of arteriosclerotic plaques in the internal carotid artery.

OBJECTIVES: The aim of this study was to investigate whether ultrasonography can characterise plaque morphology and surfaces independent of the observer. METHODS: Computer-assisted image analysis of the grey scales of B-mode scans from 15 patients with stenoses of the internal carotid artery was performed and compared with the histopathological reports. In vitro angioscopy, was used to visualise the plaque surfaces of the thromboendarterectomy specimens. RESULT: Assessment of the internal plaque structure by ultrasound showed close agreement between the two observers (P<0.01) without correlation with the histopathological results. Ultrasonography was able to characterise the plaque surfaces in 93% of cases. CONCLUSION: This investigation showed that standardised computer-assisted analysis of the internal plaque structure correlates less closely than histological investigation, but agrees closely with the surface structure of the plaque. The exclusive use of digital image processing and standardisation of the investigative technique are expected to provide even better results.

Aged↗
PubMed2002

High-resolution, contrast-enhanced magnetic resonance angiography with elliptical centric k-space ordering of supra-aortic arteries compared with selective X-ray angiography.

BACKGROUND AND PURPOSE: The objective of this study was to evaluate the relative value of high-resolution, contrast-enhanced MR angiography (CE MRA) with elliptical centric k-space ordering compared with intra-arterial x-ray angiography for imaging carotid stenosis. METHODS: Thirty patients with suspected stenosis of the carotid arteries were examined with CE MRA (1.5-T scanner) and x-ray angiography (aortic arch survey and selective imaging of both common carotid arteries). For the first time, not only the extracranial carotid bifurcation but all the vessel segments from the aortic arch to the circle of Willis were assessed by independent investigators. RESULTS: For the internal carotid artery in the region of the extracranial carotid bifurcation, there was a very close correlation between CE MRA and x-ray angiography (sensitivity, 100%; specificity, 92%). The initially suspected overestimation of stenosis on CE MRA in 3 cases was ultimately revealed to be an underestimation on x-ray angiography. CE MRA showed slightly poorer imaging of the basal vessel segments at the level of the aortic arch (because of breathing artifacts) and the intracranial vessel segments (because of small vessel caliber and venous superimposition due to delayed sequence starts). CONCLUSIONS: The MRA technique described here provides reliable results in the diagnosis of carotid stenosis and is thus suitable for replacing the invasive conventional x-ray angiography method in most cases. Further technical developments with regard to spatial resolution are still required for improved visualization of small vessels (terminal carotid branches and intracranial vessels).

Aged↗
PubMed2002

The way out.

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Angiography↗
PubMed2002

The accuracy of calculated base excess in blood.

Most equations used for calculation of the base excess (BE, mmol/l) in human blood are based on the fundamental equation derived by Siggaard-Andersen and called the Van Slyke equation: BE = Z x [[cHCO3-(P) - C7.4 HCO3-(P)] + beta x (pH -7.4)]. In simple approximation, where Z is a constant which depends only on total hemoglobin concentration (cHb, g/dl) in blood, three equations were tested: the ones proposed by Siggaard-Andersen (SA), the National Committee for Clinical Laboratory Standards (NCCLS) or Zander (ZA). They differ only slightly in the solubility factor for carbon dioxide (alphaCO2, mmol/l x mmHg) and in the apparent pK(pK'), but more significantly in the plasma bicarbonate concentration at reference pH (C7.4HCO3-(P), mmol/l) and in beta, the slope of the CO2-buffer line (mmol/l) for whole blood. Furthermore, the approximation was improved either by variation in Z (r(c)), or in the apparent pK (pK) with changing pH. Thus, from a total of seven equations and from a reference set for pH, pCO2 and BE taken from the literature (n=148), the base excess was calculated. Over the whole range of base excess (-30 to +30 mmol/l) and PCO2 (12 to 96 mmHg), mean accuracy (deltaBE, mmol/l) was greatest in the simple equation according to Zander and decreased in the following order: +/-0.86 (ZA); +/-0.94 (ZA, r(c)); +/-0.96 (SA, r(c)); +/-1.03 (NCCLS, r(c)); +/-1.40 (NCCLS); +/-1.48 (SA); and +/-1.50 (pK'). For all clinical purposes, the Van Slyke equation according to Zander is the best choice and can be recommended in the following form: BE= (1 -0.0143 x cHb) x [[0.0304 x PCO2 x 10pH-6.1-24.26] + (9.5+1.63 x cHb) x (pH -7.4)] - 0.2 x cHb x (1-sO2), where the last term is a correction for oxygen saturation (sO2). Hence, base excess can be obtained with high accuracy (<1 mmol/l) from the measured quantities of pH, pCO2, cHb, and SO2 in any sample, irrespective of whether venous or arterial blood is used.

Acid-Base Equilibrium↗