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G Lechner

Publications and source records attributed to G Lechner.

At least 19 recordsLinked to original sources
PubMed2002

[Trends in Vienna radiology--from roentgen laboratory to university clinic for radiodiagnosis].

In Vienna/Austria, with leading representatives of the so-called second Viennese medical school at the turn of the 19th to the 20th century, the detection of x-rays by W. C. Röntgen was observed with special interest. In the general hospital of Vienna, where still today the medical school of the university of Vienna is hosted, high research activities to understand the origin and the effects of X-rays were performed. Guido Holzknecht (1872-1931) was the first chairman of the central roentgen laboratory. Today, the scientific and the clinical activities at the department of diagnostic radiology are manifold and virtually all fields of imaging are covered.

Austria↗
PubMed2002

[Virtual multislice computed tomographic colonoscopy].

Virtual colonoscopy or computed tomographic (CT) colonography is a rapidly evolving technique for imaging the entire colon and detection of colorectal polyps. It uses standard helical computed tomography images of the colon and advanced imaging software to produce reformatted two- and three-dimensional views of the entire colorectum. Multi-detector row helical computed tomography has several technical advantages over single-detector row computed tomographic, including faster imaging times with the acquisition of thinner sections. The improved speed and spatial resolution of multislice computed tomography promises an increase of sensitivity and specificity, especially for the detection of colorectal lesions.

Colonic Polyps↗
PubMed2002

[Middle field and low field magnetic resonance tomography in wrist injuries].

PURPOSE: To evaluate the diagnostic value of magnet resonance imaging in comparison of a dedicated 0.2-T unit and a 1.0-T unit in patients with clinically suspected scaphoid fractures and other wrist fractures. MATERIAL AND METHODS: In 20 patients (14 m/6 f) with clinically suspected scaphoid fractures and a normal six view radiographic exam, magnet resonance imaging was performed first with the dedicated 1.0-T unit and afterwards with the 0.2-T unit within 7 days after trauma. T1 weighted spin-echo, STIR and T2-weighted 3D GRE sequences were performed. RESULTS: The 0.2 Tesla dedicated system is inferior to the 1.0 Tesla unit concerning the outcome of the 3 examiners. Especially the areas of bone bruise showed different results: each examiner detected at least two more cases of bone bruise with the 1.0 Telsa unit, which could not be defined with the 0.2 Tesla unit. CONCLUSIONS: This study shows, how utmost sensitive magnet resonance imaging is referring to unremoved fractures of the scaphoid and to other wrist abnormalities. Results with the 0.2 Tesla dedicated system was inferior compared to the 1.0 Tesla unit.

Adolescent↗
PubMed2001

[Evaluation of a computer-assisted diagnosis system in breast carcinoma].

PURPOSE: Evaluation of a computerassisted diagnosis (CAD) system (R2 linage Checker 1.2). Comparison of the results of three readers with and without knowledge of the computer results. MATERIALS AND METHODS: The mammograms of 52 patients, bilaterally in two planes each, with histologically proven carcinoma of the breast were included in the study. They were first scanned by the CAD machine and subsequently read by three readers with different degrees of experience in two sessions with and without knowledge of the computer results. RESULTS: Of the 91 views of carcinomas, the readers detected 96%, 89%, and 85%, respectively. With CAD, the values rose to 97%, 93%, and 96%. The increase of the first observer was not significant. As for the 49 areas of malignant microcalcifications, the first reader showed a significant decrease of sensitivity, the other two readers showed no significant change. The sensitivity of CAD was 74% for masses and 86% for microcalcifications at a rate of 1.8 false positive markers per image. All but two tumors were correctly marked in at least one plane. CONCLUSIONS: Use of the CAD machine led to a significant increase of sensitivity in the detection of malignant masses by two of three observers. In the case of malignant microcalcifications, and for the most experienced observer, CAD did not improve the results. The most important problem is the high rate of false positive markers.

Breast Neoplasms↗
PubMed2001

[Value of endoanal sonography in the assessment of faecal incontinence].

PURPOSE: The aim of this study was to assess the value of endoanal ultrasound (EUS) in comparison to anal manometry and operative findings in patients suffering from faecal incontinence. Patient history, localisation of sphincter defects and therapeutic modalities were analysed. METHODS: Over a 3-years period, 92 patients with faecal incontinence were investigated by endoanal ultrasound. Results were compared with anal manometry in 81 cases. RESULTS: At EUS, 27 patients (29 %) showed no sphincter defect, 18 (20 %) had an isolated internal sphincter defect, 13 (14 %) an isolated defect of the external sphincter and 34 (37 %) presented with a combined internal/external sphincter defect. Manometry correlated in 30 % with endoanal ultrasound. Compared with surgery, endoanal ultrasound was correct in 100 % and manometry in only 54 %. An obstetric trauma was most frequently related to faecal incontinence. CONCLUSION: Endoanal ultrasound is a very sensitive method for localizing anal sphincter defects and is mandatory in the assessment of patients with faecal incontinence.

Adult↗
PubMed2001

Scaphoid fractures: evaluation with high-spatial-resolution US initial results.

PURPOSE: To evaluate the diagnostic accuracy of high-spatial-resolution ultrasonography (US) in the diagnosis of scaphoid fractures. MATERIALS AND METHODS: In 72 hours after acute wrist trauma, 15 consecutive patients were examined for possible scaphoid fractures clinically and with conventional radiographs, including scaphoid views. Thereafter, high-spatial-resolution US was performed by two experienced radiologists blinded to the results of the previously performed investigations. High-spatial-resolution US of the scaphoid bones was performed from the palmar, lateral, and dorsal directions in the longitudinal and transverse planes. US findings indicative of a scaphoid fracture were cortical discontinuity and/or periosteal elevation. Finally, magnetic resonance (MR) images (short inversion time inversion-recovery, T1- and T2*-weighted) (ie, the standard) of the affected wrist were obtained and evaluated for a possible scaphoid fracture by two radiologists in consensus. RESULTS: Nine of 15 patients had scaphoid fractures. Seven (78%) of nine patients had positive findings at high-spatial-resolution US and five (56%) had such findings at conventional radiography (ie, four occult scaphoid fractures), with an accuracy of 87% and 73%, respectively. Two (50%) of four radiographically occult scaphoid fractures were depicted with high-spatial-resolution US. Sonographic findings of scaphoid fractures were either cortical discontinuity (n = 4), periosteal elevation (n = 2), or a combination of these two findings (n = 1). CONCLUSION: High-spatial-resolution US is a reliable diagnostic tool for the evaluation of occult scaphoid fractures and should be considered an adequate alternative diagnostic tool prior to computed tomography or MR imaging.

Adolescent↗
PubMed2000

Detection of focal hepatic lesions: comparison of unenhanced and SHU 555 A-enhanced MR imaging versus biphasic helical CTAP.

The purpose of this study was to compare the diagnostic sensitivity of unenhanced magnetic resonance (MR) imaging, and MR imaging with a new superparamagnetic iron oxide (SPIO)-enhanced contrast agent (SHU 555 A) with biphasic helical computed tomography during arterial portography (CTAP) in patients with focal liver lesions. Eighteen patients with a total of 91 (78 malignant, 13 benign) proven liver lesions underwent unenhanced short tau inversion recovery (STIR), T2-weighted (T2-w) TSE, and SHU 555 A-enhanced T2-w turbo spin-echo (TSE) MR imaging and biphasic helical CTAP. The standard of reference was histopathologic analysis of resected specimens in 59 lesions, intraoperative ultrasound with biopsy in 20 lesions, and CT-guided biopsy and follow-up in 12 lesions. Diagnostic performance of the imaging modalities was compared quantitatively and qualitatively by assessing lesion involvement in liver segments. There were 68 lesions detected on unenhanced T2-w TSE, which resulted in a sensitivity of 75%. With the STIR sequence, 76 lesions were detected, for a sensitivity of 84%, and with SHU 555 A-enhanced MRI, 84 lesions were detected, for a sensitivity of 92%. CTAP detected 88 lesions, for a sensitivity of 97%. The accuracy for unenhanced T2-w TSE was 98%, for STIR 99%, for enhanced-MRI 100%, and for CTAP 95%. The specificity was 100% for SHU 555 A-enhanced MRI and 95% for CTAP. SHU 555 A-enhanced MRI was superior to nonenhanced MRI (P < 0.05) and equivalent to CTAP in terms of sensitivity. Due to the absence of false-positive results on SHU 555 A-enhanced MRI, the specificity and accuracy of enhanced MRI were higher than those of CTAP, but the difference was not statistically significant (P = 0.134).

Adult↗
PubMed2000

Complications after laryngeal surgery: videofluoroscopic evaluation of 120 patients.

AIM: Videofluoroscopic assessment of the spectrum and incidence of swallowing complications after state-of-the-art laryngeal cancer surgery. MATERIALS AND METHODS: We retrospectively studied videofluoroscopic examinations of 120 patients (94 men, 26 women; mean age, 58 years) with suspected complications after laryngeal resection (partial laryngectomy, 65; total laryngectomy, 55). Swallowing function (i.e., oral bolus control, laryngeal elevation and closure, presence of pharyngeal residue, aspiration) and structural abnormalities such as strictures, fistulas and tumour recurrence were assessed by videofluoroscopy. RESULTS: Abnormalities were found in 110 patients, including strictures in nine, fistulas in six and mass lesions in 13 patients. Aspiration was found in 63 patients overall (partial laryngectomy, 61/65; total laryngectomy, 2/55), occurring before swallowing in five, during swallowing in 34, after swallowing in nine and at more than one phase in 15 patients. Pharyngeal paresis was detected in three and pharyngeal weakness in 19 patients. Pharyngo-oesophageal sphincter dysfunction was observed in 10 cases. CONCLUSION: Aspiration is a very common complication after partial laryngeal resection. It is mainly caused by incomplete laryngeal closure, sphincter dysfunction or pharyngeal pooling. Videofluoroscopy is the only radiological technique able to identify both disordered swallowing function and structural changes after laryngeal resection. Detection of these complications is crucial for appropriate further therapy.Kreuzer, S. H. (2000). Clinical Radiology55, 775-781.

Adult↗
PubMed2000

Videofluoroscopy of swallowing in symptomatic patients who have undergone long-term intubation.

OBJECTIVE: The aim of this study was to evaluate whether specific patterns of swallowing dysfunction occur in symptomatic patients after long-term intubation. SUBJECTS AND METHODS: Twenty-one patients (16 men, five women; mean age, 66 years) who presented with clinical signs of aspiration after long-term intubation (mean duration, 24.6 days) underwent videofluoroscopy. They were analyzed for functional abnormalities of the tongue, soft palate, epiglottis, hyoid and larynx, pharynx, and the upper esophageal sphincter. We assessed the presence or absence of aspiration, the type of aspiration (pre-, intra-, and postdeglutitive), and a spectrum of other swallowing abnormalities. RESULTS: There were 18 patients (86%) with radiologically proven aspiration. In another patient only laryngeal penetration occurred. There were 11 combinations of pre-, intra-, and postdeglutitive aspiration. Predeglutitive aspiration was predominant and present in 52% of our patients. We found functional abnormalities of the tongue in 48%, of the soft palate in 10%, of the epiglottis in 48%, of the pharynx in 71%, and of the upper esophageal sphincter in 24%. CONCLUSION: Patients who are symptomatic after undergoing long-term intubation do not develop a specific type or pattern of swallowing dysfunction or aspiration, but show a large variety of aspiration types and associated swallowing disorders. Nevertheless, videofluoroscopy has the ability to reveal complex deglutition disorders and to aid precise planning of individualized functional swallowing therapy.

Aged↗
PubMed2000

[Thoracic CT scan in intensive care unit patients: information supplementary to thoracic radiography].

PURPOSE: To assess the diagnostic value of thoracic CT-scans in comparison with conventional chest radiographs in ICU-patients. METHODS: Chest radiographs and corresponding thoracic CT-scans of 25 consecutive surgical ICU-patients were reviewed and interpreted independently by two radiologists. We analyzed the additional information provided by CT-scans and the diagnostic and therapeutic relevance of these findings. RESULTS: In 22 patients (88%), thoracic CT revealed 35 single additional findings, in comparison with the corresponding bedside radiographs. In 7 cases (28%), these findings (tube-malpositioning, mediastinitis, mediastinal abscess and pneumothorax) required modification of patient management. Of 7 patients with tube thoracostomy, 3 tubes were malpositioned, which was only depicted on CT-scans. In 10 of 21 cases (48%), pleural effusions could only be visualized by CT. 3 of 5 (60%) pneumothoraces were detected by CT-scans only. There were no significant complications during transport or CT-examination. CONCLUSION: Thoracic CT may provide significant information in addition to plain chest radiographs, particularly when specific problems or questions, referring to the management of ICU-patients, arise.

Abscess↗
PubMed1999

[Radiologic staging of thoracic and abdominal tumors in childhood].

Thoracoabdominal tumors in childhood can arise from all organs and affect children from the neonate to the adolescent. Better prognosis of childhood tumors, due to better biological understanding and improvement of chemotherapy, require sufficient radiological staging. Sufficiency in radiological staging needs modern cross-sectional techniques with high resolution, good availability and lower radiation dose. In general computed tomography (CT) is being used for radiological staging; increasingly MR imaging is being used because of multiplanar imaging techniques. Replacement of invasive techniques such as myelography and lymphography and modern cross-sectional techniques create painless staging conditions. Nevertheless, scintigraphy will always be a major examination technique, especially for evaluation of metastases and postoperative control examinations. The most common thoracoabdominal tumors in childhood and their staging are described.

Abdomen↗
PubMed1999

[Preoperative staging of colorectal carcinoma].

Carcinoma of the colorectum is one of the most frequent neoplasias, with an incidence of 40 in 100,000. For the effective use of new, differentiated, less invasive treatment options, exact preoperative staging of the tumor is essential. The introduction of endosonography in rectal tumor staging allows for exact differentiation of the rectal wall layers and thus of tumor stages 1-3 with median accuracy of 89%. Magnetic resonance imaging of the rectum, especially in double-contrast technique, can also be employed in high and stenosing tumors and leads to an average accuracy of 85% for the stages 1-4. Computed tomography is the method of choice in screening for metastases. In lymph node staging, all modalities show only moderate accuracy around 75%.

Colon↗
PubMed1999

[Characterization of adrenal gland space-occupying lesions. Can diagnostic imaging replace biopsy?].

This paper describes the diagnostic value of new imaging techniques in characterization of adrenal masses and evaluates the role of adrenal biopsy. For differentiation of benign and malignant adrenal lesions, sensitivities and specificities of 85-100% can be reached by unenhanced computed tomography (CT) methods, chemical shift techniques in magnetic resonance imaging (MRI), delayed enhanced CT techniques, and by evaluation of wash-out curves in contrast-enhanced CT. The diagnostic value of all CT techniques depends on threshold values. The value of dynamic contrast-enhanced MRI is under discussion and should be reevaluated by using delayed enhanced series. Biochemical and scintigraphic methods (NP 59 iodine iodomethyl-norcholesterol and MIBG meta-iodobenzylguanidine scintigrams) are valuable for the diagnosis of functional adrenal masses; however, they do not allow differentiation of benign and malignant tumors. According to excellent results of new imaging techniques in characterization of adrenal masses, the indications for fine-needle aspiration biopsy have already regressed, as have complications associated with this invasive technique.

Adrenal Gland Diseases↗
PubMed1999

Assessment of chronic constipation: colon transit time versus defecography.

OBJECTIVE: The aim of this study was to determine the value of radiological colon transit time (CTT) measurements in relation to defecography (DFG) in chronically constipated patients. MATERIALS AND METHODS: In 30 patients with chronic constipation, total and segmental CTT was determined using radiopaque markers. In all of these patients defecography (DFG) was obtained. The patients were divided into three groups: In group I, 11 patients were classified with idiopathic constipation based on low stool frequency, normal DFG, or absence of symptoms of abnormal defecation. In group II, ten patients with rectal intussusception were diagnosed by DFG. In group III, there were nine patients with rectal prolapse or spastic pelvic floor syndrome, based on results of DFG. RESULTS: Group I, idiopathic constipation (n = 11), showed increased total CTT (mean, 93 h) and segmental CTT (right colon, 33 h (36%), left colon, 31 h (33%), rectosigmoid, 29 h (31%)). In group II, intussusception (n = 10), patients had normal mean total CTT (54 h) and a relative decrease in rectosigmoid CTT (mean, 13 h (24%)). In group III (n =9), rectal prolapse (n = 5) or spastic pelvic floor syndrome (n = 4), patients showed elevated total (mean, 167 h) and rectosigmoidal CTT (mean, 95 h (57%)). Mean total CTT was significantly different between groups I and II and between groups II and III, and mean rectosigmoidal CTT was significantly different between all three groups (P < 0.05). CONCLUSION: The use of total and rectosigmoidal CTT helps to identify the underlying pathophysiology of chronic constipation. Furthermore CTT helps to identify patients, who may benefit from DFG.

Adult↗
PubMed1999

Characterization of adrenal masses using MR imaging with histopathologic correlation.

OBJECTIVE: The purpose of this study was to evaluate the sensitivity, specificity, and accuracy of MR imaging in the characterization of adrenal masses by correlating imaging findings with histopathologic results. In addition, adrenal tumors that were of an indeterminate nature on MR imaging were analyzed. SUBJECTS AND METHODS: For 114 patients with 134 adrenal masses, MR findings were compared with histologic results. In all patients, MR imaging was performed using T2-weighted fast spin-echo imaging and unenhanced and gadolinium-enhanced T1-weighted spin-echo imaging. Chemical-shift imaging was performed in 92 patients and dynamic gadolinium-enhanced studies in 108 patients. Chemical-shift images were analyzed quantitatively and qualitatively, and dynamic gadolinium-enhanced studies were qualitatively assessed. RESULTS: The sensitivity of MR imaging in differentiating between benign and malignant adrenal masses was 91%, the specificity was 94%, and the accuracy was 93%. The diagnosis at MR imaging differed from that at histology in 12 (9%) of 134 patients. Results of quantitative analyses of chemical-shift imaging techniques showed significant differences between adenomas and nonadenomas (-36.0% versus -3.7%; p < .001). Qualitative analysis provided a similar diagnostic confidence compared with quantitative analysis. Both chemical-shift and dynamic gadolinium-enhanced studies proved to be unreliable in characterizing borderline tumors (epithelial tumors with high malignant potential). Moreover, such imaging failed to allow correct diagnosis of adenomas in two patients. CONCLUSION: The characterization of an adrenal mass can be made with high sensitivity and specificity using MR imaging. The increased reliance on MR imaging seems to be based mainly on findings from chemical-shift and dynamic gadolinium-enhanced studies. The need to perform histologic sampling of incidentally discovered adrenal masses may be reduced to some problematic lesions, which will remain during the era of MR imaging.

Adolescent↗
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↗