PubMed Health⌕ Search

Biomedical subjects

G Lechner

Publications and source records attributed to G Lechner.

At least 37 records · Page 2Linked to original sources
PubMed1998

Role of magnetic resonance imaging in renal transplant recipients with acquired cystic kidney disease.

OBJECTIVES: To evaluate the impact of magnetic resonance imaging (MRI) in renal transplant recipients whose ultrasound (US) examinations of the native kidneys have met the criteria of acquired cystic kidney disease (ACKD). METHODS: The US scans of 840 renal allograft recipients were prospectively studied. In addition, 46 of 169 patients diagnosed with ACKD by US scans underwent MR examination. MRI protocols included (a) T1 and T2-weighted fast spin echo imaging, (b) T2-weighted gradient echo imaging, and (c) gadolinium-enhanced T1-weighted imaging in 7 patients with evidence of complex cysts. In the case of complex lesions, both US and MRI follow-up examinations were performed between 6 and 12 months after the prior examination. RESULTS: US examination showed ACKD in 169 of 840 patients. In addition, US revealed 8 patients with renal cell carcinomas (RCC). Of these 8 patients, 7 had evidence of ACKD. The median number of cysts depicted on US examination in native kidneys of renal transplant recipients was 3 (range 0 to 10) on both sides. MRI revealed significantly more and smaller cysts compared to US. The median number of cysts was seven on the left and nine on the right native kidneys, respectively. MRI revealed 18 complex lesions in 7 patients. Thirteen of 18 complex lesions were undetected by US. CONCLUSIONS: MRI is superior to US in depiction of simple and complex lesions of native kidneys in renal allograft recipients. MRI exhibits no overestimation of the prevalence of ACKD on the basis of the US criteria already mentioned. Advantages of MRI do not justify routine screening tests by this imaging modality. However, MRI should be used for further evaluation of complex lesions detected by US.

Adult↗
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

Hepatic perfusion after liver transplantation: noninvasive measurement with dynamic single-section CT.

PURPOSE: To compare hepatic perfusion values after orthotopic liver transplantation with those in healthy volunteers. MATERIALS AND METHODS: Dynamic single-section computed tomography (CT) of the liver was performed in 50 participants, including 30 study patients who had undergone orthotopic liver transplantation and had no clinical evidence of postoperative complications (mean age, 53.7 years) and 20 healthy volunteers (control subjects) (mean age, 59.0 years). CT scans were obtained at a single level to include the liver, spleen, aorta, and portal vein. Scans were obtained over 88 seconds (one baseline scan followed by 16 scans every 2 seconds and, then, eight scans every 7 seconds) beginning with the injection of 40 mL of contrast agent (flow rate, 10 mL/sec). On each CT scan, the attenuation of these organs was measured in regions of interest to provide time-attenuation curves. From these data, the arterial, portal venous, and total perfusion of the liver were calculated, and the hepatic perfusion index was assessed. RESULTS: In control subjects and study patients, respectively, mean arterial hepatic perfusion was 0.16 and 0.25 mL/min/mL (P = .001 [two-tailed paired Student t test]), mean portal venous perfusion was 1.22 and 1.26 mL/min/mL, mean total liver perfusion was 1.38 and 1.50 mL/min/mL (difference not significant), and the mean hepatic perfusion index was 0.12 and 0.16 (P = .002). CONCLUSION: Arterial hepatic perfusion was significantly increased after orthotopic liver transplantation, but differences in portal venous and total liver perfusion were not significant. Dynamic single-section CT might also help evaluate hepatic vascular complications, chronic transplant rejection, and hepatic perfusion in liver cirrhosis.

Adult↗
PubMed1998

[Computer-assisted diagnosis in mammography: the R2 ImageChecker System in detection of spiculated lesions].

Because of the rapid development of computer systems for digitalization and image analysis, they play an increasing important role in computer-assisted diagnosis (CAD). Especially in the field of mammography, the early signs of malignancy are relatively uniform and therefore more easily detected by a computer algorithm. In this study, we tested one of the few commercially available systems for the detection of both microcalcifications and suspicious, spiculated solid lesions on 40 cases of proven breast carcinomas. These mammograms were analyzed by three independent observers with and without knowledge of the computer results, respectively. Depending on the time of their radiologic experience, the sensitivity of the observers alone was 92.4%, 86.1% and 82%. With knowledge of the computer interpretation, sensitivity of all three observers rose significantly to 100%, 92.7%, and 95%, respectively. However, due to a high number of false positive results of the computer algorithm (0.4 markers per image), the positive predictive value of the interpretations worsened from 100%, 92.7%, and 95.5% to 86.4%, 97.3%, and 91.1%, respectively. It can be expected that future developments will soon overcome this problem and CAD will become an effective tool in screening mammography.

Adult↗
PubMed1997

Enhancement of hepatic parenchyma, aorta, and portal vein in helical CT: comparison of iodixanol and iopromide.

OBJECTIVE: The purpose of this study was to determine hepatic, aortic, and portal vein enhancement with a new dimeric, nonionic, isotonic contrast medium (iodixanol) in a routinely performed helical CT protocol and compare enhancement characteristics with those of a monomeric, nonionic, low-osmolality contrast medium (iopromide). SUBJECTS AND METHODS: In 81 patients, we injected 150 ml of iodixanol (320 mg I/ml), iodixanol (300 mg I/ml), or iopromide (300 mg I/ml). Injection rate was 5 ml/sec. A dual-phase helical CT scan was obtained (first helical scan began at 30 sec. second helical scan began at 70 sec), and enhancement characteristics were assessed. Results were analyzed taking into account various intrinsic parameters of patients. RESULTS: During the second imaging phase, iodixanol at 320 mg I/ml and iodixanol at 300 mg I/ml provided significantly higher enhancement of the liver (75 H, 69 H, 62 H), aorta (144 H, 140 H, 122 H), and portal vein (147 H, 147 H, 118 H) than did iopromide at 300 mg I/ml. No significant differences were observed during the first imaging phase. CONCLUSION: The combination of higher vascular and parenchymal enhancement levels after injection of the isotonic agent may represent a different quality of tissue enhancement. Such an enhancement would be characterized more by a higher contribution of the blood pool compartment to absolute enhancement levels than by a contribution of the interstitial compartment. Further studies are needed to determine whether the use of isotonic agents effects lesion conspicuity.

Aorta, Abdominal↗
PubMed1995

Biliary sludge after liver transplantation: 2. Treatment with interventional techniques versus surgery and/or oral chemolysis.

OBJECTIVE: Interventional treatment of biliary sludge in liver transplant recipients includes transhepatic biliary drainage and saline irrigation, catheter chemolysis and/or basket extraction, and endoscopic intervention. The purpose of this study was to compare these interventional procedures with oral chemolysis and with surgical treatment of biliary sludge in order to evaluate the effectiveness of interventional procedures as an alternative to surgery in the treatment of this complication. MATERIALS AND METHODS: We retrospectively evaluated the outcome of several forms of treatment for biliary sludge occurring after liver transplantation in 49 cases. Treatments included oral chemolysis with chenodeoxycholic acid (n = 35), percutaneous transhepatic biliary drainage (n = 13) followed by irrigation with heparinized saline solution (n = 4), intraluminal chemolysis with glycero-octanoate-carnosine and bile salts-EDTA (n = 3) and/or basket extraction (n = 5), and endoscopic intervention (n = 2) or surgery (n = 26). Oral chemolysis was attempted in all cases of biliary sludge if no other complications were present. If this conservative treatment failed and the sludge was limited to the main bile ducts, interventional procedures were attempted. Surgical removal of the sludge (n = 15) or retransplantation (n = 5) without any attempt at prior nonsurgical treatment was performed if concomitant complications were present (n = 14) or if the extent of the sludge was considered too time-consuming for an interventional attempt (n = 6). The six patients in whom nonsurgical treatment failed underwent surgery. Treatment was considered successful if cholangiograms obtained after therapy showed no more evidence of sludge. Treatment was considered a failure if biliary sludge was shown after therapy by means of cholangiography, surgery, or autopsy. RESULTS: Complete disappearance of biliary sludge as a result of oral chemolysis was achieved in 14 (40%) of 35 cases. Interventional procedures were performed in 15 of the patients in whom oral treatment failed. After percutaneous transhepatic biliary drainage, the sludge was successfully removed by chemolysis with glycero-octanoate-carnosine in three cases, by basket extraction in one case, and by a combination of chemolysis and basket extraction in three cases. In two other cases, underlying recurrent tumor was treated palliatively with percutaneous transhepatic biliary drainage or endoscopic stenting. Irrigation with heparinized saline solution failed in four cases, and percutaneous or endoscopic basket extraction failed in one case each. Surgical treatment was successful in 18 (86%) of 21 cases, and retransplantation was successfully done in five patients. In all, interventional techniques were used in 43% of the patients with biliary sludge who could not be treated successfully with oral chemolysis, and the overall success rate was 60%. CONCLUSION: Interventional techniques are effective therapeutic alternatives for treating biliary sludge occurring after liver transplantation and should be considered before surgical procedures. An indication for interventional procedures in biliary sludge is lack of success of oral chemolysis and an absence of other complications that require surgery or retransplantation.

Adolescent↗
PubMed1995

Biliary sludge after liver transplantation: 1. Imaging findings and efficacy of various imaging procedures.

OBJECTIVE: Biliary sludge (inspissated, thickened bile or collective collagen tissue from destroyed [or necrotic] bile duct walls) can be found a few days to several years after liver transplantation, mainly in the common and main hepatic bile ducts. The purpose of this study was to review the imaging findings of biliary sludge occurring after liver transplantation and to determine the relative merits of various imaging procedures (cholangiography, CT, and sonography) for establishing the diagnosis. MATERIALS AND METHODS: Cholangiograms, sonograms, and CT scans obtained in 352 patients with 400 liver transplants were reviewed retrospectively for evidence of biliary sludge. In all patients, T-tube cholangiograms were routinely obtained 7 and 30 days and 3 months after transplantation. Thereafter, in the absence of findings, the T-tube was removed. In all patients, sonograms were obtained immediately, 2 and 7 days after transplantation. Additional cholangiograms were obtained when biliary complications were suspected (T-tube cholangiograms in 215 patients, percutaneous transhepatic cholangiograms in 79 patients, and endoscopic retrograde cholangiograms in five patients after T-tube removal). Additional sonograms were obtained in 289 patients and CT scans in 238 patients when complications were suspected. The findings of these various imaging studies were analyzed and compared with each other, with the clinical course of the patient, and with surgical and histologic findings to determine the relative merits of each imaging method for the diagnosis of biliary sludge. Criteria for the diagnosis of biliary sludge were filling defects or pluglike obstruction seen on cholangiograms or material filling the bile ducts seen on sonograms or CT scans. The radiologic diagnosis of biliary sludge was certified by gross specimens obtained at surgery (n = 21) or autopsy (n = 2) or by complete disappearance of the radiologic findings with specific oral or interventional treatment (n = 28). RESULTS: Biliary sludge was diagnosed on the basis of radiologic findings in 51 (13%) of 400 transplanted livers. Cholangiograms (T-tube in 34, percutaneous transhepatic cholangiography in seven, a combination of T-tube and percutaneous transhepatic cholangiography in eight, and a combination of endoscopic retrograde and percutaneous transhepatic cholangiography in two cases) showed biliary sludge in all 51 cases. Cholangiographic findings included filling defects in 34 (67%) and obstruction of the bile duct with pluglike appearance in 17 (33%) of the 51 cases. Dilatation of bile ducts was present in 32 (63%) of the 51 cases. The presence of biliary sludge was certified in 50 of these cases, with one case turning out to be a sutural granuloma at autopsy. On sonograms, biliary sludge was shown as echogenic material in the main bile ducts in only 16 (31%) of the 51 cases, with dilatation of bile ducts in 12 of them. In 10 others (20%), sonograms showed dilatation of the bile ducts but did not show the sludge itself. CT scans did not show the sludge in any of the 12 cases in which they were obtained. CONCLUSION: Our results show that cholangiography is the only accurate imaging method for diagnosing biliary sludge after liver transplantation. Sonography is limited and CT is of no value for this purpose. In the absence of a T-tube, endoscopic retrograde or percutaneous transhepatic cholangiography should be used. Otherwise, T-tube cholangiography is the method of choice. Filling defects and obstruction of the bile ducts with pluglike material are characteristic findings of biliary sludge seen on cholangiograms.

Adolescent↗
PubMed1994

Determination of optimal time window for liver scanning with CT during arterial portography.

PURPOSE: To determine the optimal time window for scanning the liver with computed tomography (CT) during arterial portography (CTAP). MATERIALS AND METHODS: After vasodilation and contrast medium injection into the superior mesenteric artery (80 mL at 5 mL/sec), 25 repeated scans were obtained at a single level within 83 seconds in 13 patients. Attenuation was measured on every scan, and time-attenuation curves were created. Enhancement characteristics of the portal vein, liver parenchyma, aorta, and tumors were evaluated. RESULTS: Parenchymal enhancement of more than 60 HU was achieved between 18 seconds +/- 4 (standard deviation) and 67 seconds +/- 15, and high parenchyma-to-tumor contrast of more than 50 HU occurred between 18 seconds +/- 3 and 62 seconds +/- 14. CONCLUSION: To scan the liver within such a narrow time window, a spiral CT technique is necessary. When the above injection parameters are used in CTAP, the spiral CT sequence should be started 20 seconds after the beginning of the injection.

Adult↗
PubMed1993

[The sonographic diagnosis of recurrences after parathyroid autotransplantation. The preliminary results of a prospective study].

Reactive renal hyperparathyroidism is a complication of chronic renal failure. The treatment of choice is resection of all four parathyroid glands and autotransplantation of a piece of parathyroid into the muscles of the fore-arm. In a prospective study, the transplant site was examined postoperatively in 35 patients by sonography on at least one occasion. In 3 patients (8.6%) enlargement of the autotransplant was observed and in 2 patients this was associated with clinical and biochemical changes; these were also confirmed histologically. The sonographic appearances of satisfactory and abnormal transplants are described. The value of the method remains to be determined.

Adult↗
PubMed1993

[Drain fistulography. Radiological sphincter identification in high anal fistulae].

To warrant permanent surgical cure of high anal fistulae, while avoiding at the same time faecal incontinence due to inadvertent division of the puborectalis muscle, distinction between a trans- and suprasphincteric fistula track is essential. This differentiation is often crucial, since digital rectal palpation and conventional fistulography tend to be unreliable. Therefore we developed a radiological technique of imaging the anorectal fistulous track, "drain fistulography". After silicon drainage of the fistula the contrast visualization of anal canal, rectum and fistula drain allows to assess the topographic relation between fistula and anal sphincters as well as the sphincteric functional component above the fistula. A trans-sphincteric fistula track was demonstrated in 7 of 8 patients (5 with recurrent fistulae) by means of "drain fistulography", permitting complete laying open of each fistula in a second operation. In one patient a suprasphincteric fistula track was found and a "mucosal flap repair" was carried out. After a mean observation time of 53 months all patients are perfectly continent and free of recurrence. The method of "drain fistulography" is a valuable diagnostic tool to select the appropriate definitive surgical procedure in the treatment of high anal fistulae.

Adult↗
PubMed1992

[X-ray measurement of the level of rectal carcinomas and its dependence on the functional status of the pelvic floor].

The influence of the various functional states of the pelvic floor on the radiological assessment of the tumour levels and the distant tumour-free distance in rectum neoplasms was investigated. The parameters "anal canal length", "anorectal angle" and "impression of the puborectalis muscle" were measured in lateral distant views of the rectum in a series of healthy controls (n = 160). In addition, these parameters and the "distant tumour-free distance" were measured in patients with rectal cancer (n = 40). For each patient the lateral distant view at rest, during contraction and during maximal relaxation (straining) of the pelvic floor, were available for retrospective analysis. Depending on the various functional states of the pelvic floor, the differences between the same parameters were statistically significant (p less than 0.001). The average difference between the distal tumour-free distances during contraction and straining was 1.5 cm. Therefore, measurements of this distance in one lateral distant view exclusively may result in an inaccurate assessment of the tumour level. For the individual planning of extreme sphincter-saving surgery in low rectal cancer based on lateral distant view, the view at rest appears to be the most suitable. However, additional x-rays during contraction and maximal relaxation of the pelvic floor, respectively, should be available to identify the view at rest for an accurate assessment of the tumour level and to avoid misinterpretations which would have falsely influenced the planning of rectum surgery in 20% of our cases.

Adult↗
PubMed1991

Sonographic demonstration of septicaemia with gas-forming organisms after liver transplantation.

Sepsis with gas-forming organisms, e.g. Clostridium perfringens and anaerobic streptococci occurred in three of 120 liver-transplant recipients (2.5%). The diagnosis was made in all three patients by bedside ultrasound, before blood cultures revealed bacterial growth. Floating high amplitude echoes within the extra- and intrahepatic portal veins and persistent small high amplitude echoes in the non-dependent portion of the liver are indicative of portal venous gas and should prompt further laboratory investigations.

Adult↗
PubMed1991

[Correlation of the x-ray morphology with the histopathological staging and grading of colorectal cancer].

In a retrospective study stage grouping as well as histopathological grading (G category) of colorectal carcinomas was compared to radiographic findings at double contrast barium enema. A good correlation of tumour stage according to Dukes and the pT category and histopathological grading could be established to radiographic morphology. Apple core lesions and eccentrically obstructing neoplasms as well as saddle-like tumours exhibited worse staging and grading categories in comparison to polypoid lesions; plaque-like tumours are probably in between. It can therefore be assumed that the radiographic appearance of colorectal carcinomas may be a valuable tool to indicate stage group and G-category and thus offer information about patient prognosis.

Adult↗
PubMed1991

[Balloon dilatation of benign esophageal stenoses].

Benign stenoses of the oesophagus have been conventionally treated by endoscopic bougienage and were operated on in case of failure. Now that balloon catheters with large balloon diameters are available, interventional radiological dilatation of enteric strictures can be easily performed. In case of eccentric high-grade stenosis with or without blind loop, stenosis is often easier to manage and associated with less risk with an angiographic guide wire and catheter than by endoscopy. 53.3% of the patients were referred to balloon dilatation after failed endoscopic bougienage. The indications for balloon dilatation were anastomotic stenosis (66.2%), peptic stenosis (16.9%), achalasia (7%), pylorospasm (5.6%) and stenosis due to pemphigus vulgaris, acid ingestion and (in one case) a Schatzki ring. The complication rate was low at 1%. The experience collected with 297 dilatations in 71 patients with benign oesophageal stenosis, is reported.

Adult↗
PubMed1991

[The ultrasonic diagnosis of an ulnar nerve lesion in the sulcus area].

The diagnostic accuracy of ultrasound in ulnar nerve irritation syndrome was evaluated. 7 patients were examined and compared to a control group of 5 healthy persons. We correlated pathological changes with clinical signs and symptoms, nerve conduction velocity and with the operation report. Ultrasound yielded no false negative or false positive results and is therefore a valuable method for the evaluation of the ulnar nerve irritation syndrome especially in cases of vague localisation of the nerve lesion.

Adult↗
PubMed1991

Parosteal osteosarcoma. 2-23-year follow-up of 33 patients.

In a study of the working group for bone tumors of the German Orthopedic Society, 33 patients with a histologically confirmed parosteal osteosarcoma at reexamination underwent clinical and radiographic follow-up. Local recurrence occurred in all the cases after intralesional surgery and in 4 of 8 cases after marginal excision. The grade of differentiation was decisive for the prognosis. Despite intralesional surgery, the prognosis for Grade 1 tumors was good. Metastases developed in 1 of 23 patients with a Grade 1 tumor and in 4 of 9 patients with a Grade 2 tumor. The single patient with a Grade 3 tumor was treated with adjuvant chemotherapy and was free of disease after 5 years.

Adolescent↗
PubMed1990

[Pneumothorax in intensive care patients. The value of tangential views].

In 55 intensive-care patients an additional tangential view of the chest was taken to demonstrate or exclude a pneumothorax in patients with sudden deterioration of gas exchange and negative ap-chest x-ray, if there was a suspicion of pneumothorax or a confirmed small pneumothorax in the ap-view. In 14 of 42 cases (33.3%) with negative or suspected ap-chest x-ray the tangential view revealed a pneumothorax. 6 of these 14 pneumothoraces were under tension. In 7 out of 11 patients (63.6%) with small pneumothorax, the tangential view showed additionally a tension pneumothorax.

Adult↗