Biomedical subjects

W Dock

Publications and source records attributed to W Dock.

At least 19 recordsLinked to original sources

PubMed1998

[Prevalence of abdominal aortic aneurysms: a sonographic screening study].

PURPOSE: To determine the prevalence of abdominal aortic aneurysms (AAA) in males above 60 years of age. METHODS: 1043 males of 60 years of age or older underwent sonographic examinations of the abdominal aorta. All of the candidates had volunteered for the examination, and special care was taken to avoid preselection of the candidates. Wherever possible, information was obtained on the following risk factors: cholesterol level, nicotine, diabetes, insulin and other medication, hypertonia and cardiac risk. RESULTS: An AAA was diagnosed in 2.59% of the cases, while ectasia of the abdominal aorta was detected in 11.89%. The mean diameter of the aneurysms was 39.1 mm. Significant correlations between the various risk factors and abnormalities of the abdominal aorta could be established in patients suffering from angina pectoris (p = 0.004) and from congestive heart failure (p = 0.014). CONCLUSIONS: AAA in males above 60 occurs in 2,590 out of 100,000 cases. The most noteworthy risk factors in the development of AAA are cardiovascular disorders.

Age Factors↗

PubMed1998

Effects of a microbubble contrast agent on breast tumors: computer-assisted quantitative assessment with color Doppler US--early experience.

PURPOSE: To evaluate objectively the effects of a microbubble contrast agent on the color Doppler ultrasound (US) examination of breast lesions. MATERIALS AND METHODS: Forty-seven patients aged 23-71 years underwent color Doppler US before and after intravenous injection of a microbubble contrast agent. A 3-minute computer-assisted assessment of the color pixel density (CPD) was used to evaluate objectively the increase in the number of color Doppler US signals, the transit time of the microbubble bolus, and the potential additional differential diagnostic information. RESULTS: Peak CPD at contrast agent-enhanced color Doppler US was 14.3% +/- 8.1 (mean +/- 1 standard deviation) for carcinomas and 9.3% +/- 4.9 for benign lesions (P = .04). The time to peak enhancement was shorter in carcinomas (38 seconds +/- 20) than in benign tumors (71 seconds +/- 48, P = .02). Final CPD was close or equal to baseline values. With the median of 13% for peak CPD as a threshold, the sensitivity for this parameter was 55%, the specificity was 79%, and the accuracy was 62% (P = .04). For a median time to peak of 50 seconds, the sensitivity was 84%, the specificity was 57%, and the accuracy was 76%. CONCLUSION: After microbubble contrast agent injection, carcinomas and benign lesions behave differently in degree, onset, and duration of Doppler US enhancement. High interindividual variability and temporal variations in the Doppler US signal still limit the value of these criteria for prospective diagnosis.

Adult↗

PubMed1997

[Diagnostic imaging after liver transplantation].

INTRODUCTION: Orthotopic liver transplantation (OLT) has become an accepted treatment for end-stage liver disease. However, postoperative complications result in significant patient morbidity and mortality. Early detection and treatment of these complications is therefore of utmost importance. MATERIALS AND METHODS: We retrospectively reviewed the postoperative complications of the patients who underwent OLT at our institution. Duplex Doppler sonography and cholangiography were the primary imaging modalities in postoperative evaluation of the transplanted liver. Other important techniques were CT, MRI and angiography, which may contribute to a reliable diagnosis of vascular or biliary complications. RESULTS: Second to primary organ dysfunction, vascular complications are the most frequent cause of graft loss. Thrombosis of the hepatic artery is the most common and most serious vascular complication, with a reported incidence from 4 to 42%. Bile duct sludge, leaks and strictures are frequent complications after liver transplantation, which can contribute to graft dysfunction. Biliary tract complications usually occur within the first 3 months and require interventional radiological or surgical therapy. Since liver transplant recipients undergo immunosuppressive therapy, they are at increased risk of developing late post-transplant malignancies, which are best depicted by US, CT or MRI. However, radiological diagnosis of lympho-proliferative disorder has to be confirmed by liver biopsy. CONCLUSION: Cholangiography and Duplex sonography are routinely used in the postoperative evaluation of patients with OLT. CT, MRI, and angiography are problem-solving tools in equivocal cases.

Diagnostic Imaging↗

PubMed1997

Intraoperative and early postoperative colour Doppler sonography after carotid artery reconstruction: follow-up of technical defects.

We studied 50 patients with intraoperative colour-coded Doppler sonography (CCDS) after carotid artery reconstruction. Technical defects could be detected in 19 cases (38 %): residual plaques in 9, flaps in 8 and strictures in 2. In 9 cases (18 %) the carotid endarterectomy was revised. One residual plaque and one residual stricture caused thrombosis at the operative site a few hours postoperatively. One of the patients with residual plaques developed a high-grade stenosis within the follow-up period. Of the patients with residual plaques two had a medium-grade stenosis at follow-up. Six flaps decreased in size or disappeared within 1 week after operation. No patient with a flap developed a stenosis within the follow-up period. Our findings seem to indicate that correction of intimal flaps less than 10 mm in size is not necessary.

Aged↗

PubMed1996

Stenoses of the first segment of the vertebral artery: difficulties in angiographic diagnosis.

Pathology at the origin of the vertebral artery may be the cause of incapacitating vertebrobasilar insufficiency (VBI). Preoperative diagnosis is made primarily on angiographic criteria. We compared intraoperative and angiographic findings in 30 patients and found important diagnostic discrepancies in patients with a caudal, ventral or dorsal origin of the vertebral artery. In their angiograms, vessel superimposition led us to over look 3 ostial stenoses and 10 stenoses due to kinking. Angiographic assessment of patients with VBI can be difficult. Adequate visualisation of the origin of the vertebral artery is mandatory for accurate diagnosis.

Aged↗

PubMed1996

Coefficient of variation: a powerful Doppler ultrasonographic parameter for detection of renal artery stenosis.

The aim of our study was to objectively compare the effectiveness of various Doppler parameters in the diagnosis of renal artery stenosis. In three sheep, variable degrees of renal artery stenosis were induced and renal segmental arteries were investigated using pulsed Doppler sonography. In each animal the standard deviation of the instantaneous peak velocity within one cardiac cycle normalized by the mean peak velocity (coefficient of variation) had significantly higher normalized regression coefficients (k* = -0.215, average of three animals) when compared to resistive index (k* = -0.090) and acceleration index (k* = -0.069). In each individual animal, coefficient of variation detected lower pressure gradients (6.3 mm Hg, average value) than did resistive index (13.4 mm Hg) or acceleration index (17.3 mm Hg). The coefficient of variation may detect the presence of pressure gradients in renal artery stenosis more accurately than acceleration index or resistive index.

Animals↗

PubMed1995

Intrarenal Doppler ultrasonography: which vessel should be investigated?

The aim of our study was to determine whether the site of intrarenal Doppler measurement influences diagnosis of renal artery stenosis. In an experimental test, three sheep with variable degrees of renal artery stenosis were investigated. In each animal, the resistive index from renal segmental arteries correlated better with mean pressure gradient (r = 0.85, 0.71, 0.85) and had lower standard deviation (s = 0.02 to 0.05) than resistive index from interlobar arteries (r = 0.48, 0.54, 0.61) (s = 0.03 to 0.11). In two animals the difference was significant (correlation: P < or = 0.01, P = 0.13, P < or = 0.05; standard deviation: P < or = 0.01, P < or = 0.34, P < or = 0.05). For detecting renal artery stenosis, vessels within the renal sinus should be used for Doppler sampling.

Animals↗

PubMed1993

[Ultrasound-guided needle biopsies of thoracic space-occupying lesions].

This study is concerned with the results and experience gained from performing ultrasound-guided needle biopsies of thoracic masses in 56 patients. The accuracy of the biopsy results were related to the certainty of the method, the visibility of the biopsy needle on real time images, the effect of biopsy needle thickness and tumour size. Correct diagnosis was achieved in 84.6%. Inability to see the biopsy needle resulted in only 5.4% of cases and only when using a low frequency transducer (3 MHz). The thickness of the biopsy needle affected the accuracy of the biopsy, since all false negative or inconclusive biopsies resulted from the use of fine calibre needles. There was no significant correlation between tumour size and the accuracy of the biopsy results.

Adult↗

PubMed1993

[Stenoses and occlusions of the abdominal aorta in patients less than 40-years old].

Stenosis or occlusion of the abdominal aorta in patients under 40 years of age is either due to a congenital malformation (abdominal aortic coarctation) or due to idiopathic aortitis (Takayasu's arteritis). Some authors, however, consider abdominal aortic coarctation as a subtype of Takayasu's arteritis. We evaluated 9 of our cases and 108 well-documented cases from the literature to help decide the question whether abdominal aortic coarctation is an entity of its own or a subtype of Takayasu's arteritis. In coarctation there is a slight male predominance, patients are usually younger than 20 years of age, and the short aortic stenosis is suprarenal with involvement of the renal arteries. In Takayasu's arteritis females are predominantly affected, patients are usually over 20 years of age, and the long aortic stenosis or occlusion is infrarenal without involvement of the renal arteries. Abdominal aortic coarctation must therefore be considered as a separate disease. Aortography is important, because the morphology of aortic alterations often allows a radiological diagnosis.

Adult↗

PubMed1993

Knee function after operation for malignancy of the distal femur. Quadriceps muscle mass and knee extension strength in 21 patients with hinged endoprostheses.

We evaluated quadriceps muscle mass and knee extension strength in 21 patients after resection and endoprosthetic replacement of the distal femur for malignant bone tumor. In all cases, a modular cementless, hinged prosthesis had been used. The mean follow-up period was 4 (2-9) years. Muscle mass was measured ultrasonographically, and strength isokinetically with a Cybex 6000 dynamometer. All the data for the operated side are given as percentage of the non-operated side. The average quadriceps mass was 48 (27-70) percent. The average peak torque was 31 (14-48) and 36 (18-55) percent at the speed of 30 degrees/s and 90 degrees/s, respectively. The reduction in extension strength became greater with increasing flexion. There was a moderate correlation between muscle mass and muscle strength. Most of the patients who had kept more than 40 percent of the quadriceps mass had more than 30 percent peak torque. Patients with excellent function (Enneking 1987) had more quadriceps muscle mass and higher strength than those that were merely good with the borderline at about 40 percent muscle mass.

Adolescent↗

PubMed1993

Duplex sonography of mammary tumors: a prospective study of 75 patients.

Seventy-five breast neoplasms have been examined with duplex sonography to establish the optimal threshold value of systolic peak flow velocity to differentiate benign from malignant tumors. It could be shown that a systolic peak flow of > or = 0.2 m/s (Doppler angle corrected to 0 degrees) provides the best relationship between sensitivity and specificity concerning characterization of tumors. However, the data we obtained indicate that only positive findings are potentially reliable. Negative sonographic results should not be used to conclude a lesion is benign. Additionally, a new algorithm for breast tumors in which duplex sonography is an integral part is discussed.

Adult↗

PubMed1993

[The radiologic clinical picture of primary bone lymphoma].

Primary lymphoma of bone is a rare form of non-Hodgkin lymphoma which involves a single bone and has a relatively good prognosis following radiation therapy. We observed 17 histologically verified cases and found 97 cases in the literature. This rare tumour may occur at any time in adults and usually affects the metaphyses of long bones. It produces osteolytic changes and usually only mild periosteal reactions. Radiologically as well as histologically, differentiation from other highly malignant bone tumours is extremely difficult and sometimes impossible. A correct diagnosis can only be made from an accurate knowledge of the radiological appearances, localisation of the tumour and age of the patient.

Adolescent↗

PubMed1992

[The technic of adrenal biopsy. Ultrasound versus CT as the guidance method].

Forty-seven needle biopsies of the adrenal glands have been performed under ultrasound or CT guidance. The aim was to clarify the best guidance method, the best approach, the choice of biopsy needle and possible complications. Analysis of the results provided the following answers: 1. A mass in the right adrenal can be biopsied under ultrasound control by a transhepatic approach. Small lesions of the left adrenal are best approached under CT guidance. In these cases a subcostal angled approach is advised. 2. Cutting biopsy needles provide better results than aspiration biopsy needles. 3. The complication rate of adrenal biopsies is very low if thin cutting needles are used.

Adrenal Glands↗

PubMed1992

["Pseudo-dissection" in an abdominal aortic aneurysm].

Sonography of 52 patients with aneurysms of the abdominal aorta revealed in 7 cases hypoechoic crescent-like zone between parietal thrombus and the aortic wall which simulated aortic dissection. Duplex-sonography was performed in all cases and no flow could be detected in this area. In two patients intraoperatively several milliliters of a serous fluid could be aspirated from this zone which confirmed the suggestion of seroma within the parietal thrombus. This observation may be found rather frequently and should not be a reason for immediate surgery.

Aortic Dissection↗

PubMed1992

[The problem of the closed abdominal injury in polytrauma patients].

The histories of 66 patients with blunt abdominal trauma requiring surgery in the period from 1985 to 1989 were analysed. The patients were divided into three groups on the basis of the other injuries present. Group I, isolated blunt abdominal trauma and blunt abdominal trauma with slight concomitant injuries (18 patients, ISS 17.17 +/- 1.40); group II, blunt abdominal trauma with severe concomitant injuries but without craniocerebral trauma (23 patients, ISS 29.34 +/- 1.45); and group III, blunt abdominal trauma with severe concomitant injuries and an additional craniocerebral trauma (25 patients, ISS 31.08 +/- 1.27, GCS: 10.04 +/- 0.88). Initially, the diagnosis was made in 23 cases by means of diagnostic peritoneal lavage and in 43 cases by means of sonography. The subsequent laparotomy revealed the ultrasound findings to have been false-positive in 3 cases. No false-negative ultrasound findings were demonstrated at all. Peritoneal lavage, on the other hand, was found to have yielded false-negative and false-positive findings in 2 cases each. Counting from the time of admission, the time up to diagnosis of the intra-abdominal injury was 85 +/- 14.3 min in group I, 82 +/- 9.9 min in group II, and 86 +/- 12.9 min in group III. Thus, the presence of severe additional injuries did not lead to any significant delay in the diagnosis of blunt abdominal injury requiring surgery. The total mortality rate was 18.18% (group I, 11.1%; group II, 21.7%; group III, 20.0%). Six patients died in the acute phase and a further six patients during their stay on the intensive care ward.

Abdominal Injuries↗

PubMed1992

Prospective clinical study with in vitro endothelial cell lining of expanded polytetrafluoroethylene grafts in crural repeat reconstruction.

A nonrandomized prospective clinical study was undertaken to evaluate the technique and efficacy of in vitro endothelial cell lining of synthetic grafts. Twenty-six patients (10 men and 16 women with a mean age of 68.4 years; range, 49 to 80 years) with end stage chronic peripheral vascular disease requiring reoperation were entered into the study. In 13 patients venous endothelial cells were harvested 4 to 7 weeks before operation, grown to confluency in culture flasks, and seeded onto the inner surface of expanded polytetrafluoroethylene grafts. Thirteen patients received untreated expanded polytetrafluoroethylene grafts and served as a control. A scoring system with use of intraarterial angiography was used to assess disease severity. No statistically significant differences in angiographic score were seen between the two groups, indicating comparable severity of disease. Early secondary graft patency (0 to 30 days) was 92% for the in vitro endothelial cell lining group and 53% for control patients. The amputation rate after 18 months for the in vitro endothelial cell lining group was 15%, with a 31% rate in the control group. The functional performance of the in vitro endothelial cell lining bypasses was superior to that of untreated bypass grafts during the observed follow-up period. These early results suggest that in vitro endothelial cell lining is a method that can reduce the early occlusion rate now seen after repeat reconstruction of crural vessels.

Aged↗

PubMed1992

[Aneurysms of the portal vein: an evaluation of 21 cases].

Reviewing 17 cases from the literature and 4 own cases we tried to throw light on the clinical and radiological appearance of the aneurysms of portal vein. The evaluation was performed in respect of sex, age, size, localisation and eventual combination with a portal hypertension. It appears that these aneurysms can be found at any age and that there is no sexual preference. In most cases these aneurysms are asymptomatic. In rare cases they may cause portal hypertension. This seems to be possible only with extrahepatic but not with intrahepatic location of the aneurysms.

Adult↗

PubMed1991

[The value of different clinical and imaging procedures for the postoperative follow-up of extra-anatomical bypasses].

In order to judge the patency of extra-anatomical by-passes in the lower extremities, 24 patients with 29 by-passes were examined clinically (palpation of the by-pass pulse, Fontaine staging, Doppler index) and by imaging methods (i-v DSA, Duplex sonography, colour-coded Doppler sonography). The value of these methods was compared. Sonography was found to be the ideal method for follow-up. Palpation was unreliable, particularly for femoro-femoral by-passes. The Doppler index and the Fontaine method provided no information about the actual state of the bypass. Angiography is indicated only if further vascular reconstruction is planned.

Aged↗