Biomedical subjects

A Dessl

Publications and source records attributed to A Dessl.

28 records · Page 2Linked to original sources

PubMed1997

[Virtual endoscopy with post-processing helical CT data sets].

PURPOSE: The purpose of this work was to test a newly developed, post-processing software for virtual CT endoscopic methods. Virtual endoscopic images were generated from helical CT data sets in the region of the shoulder joint (n = 2), the tracheobronchial system (n = 3), the nasal sinuses (n = 2), the colon (n = 2), and the common carotid artery n = 1). Software developed specifically for virtual endoscopy ("Navigator") was used which, after a previous threshold value selection, makes the reconstruction of internal body surfaces possible by an automatic segmentation process. We have evaluated the usage of the software, the reconstruction time for individual images and sequences of images as well as the quality of the reconstruction. All pathological findings of the virtual endoscopy were confirmed by surgery. RESULTS: The post-processing program is easy to use and provides virtual endoscopic images within 50 seconds. Depending of the extent of the data set, virtual tracheobronchoscopy as a cine loop sequence required about 15 minutes. Through use of the threshold value-dependent surface reconstruction the demands on the computer configuration are limited; however, this also created quality problems in image calculation as a consequence of the accompanying loss of data. CONCLUSIONS: The Navigator software enables the calculation of virtual endoscopic models with only moderate demands on the hardware.

Artifacts↗

PubMed1997

[Open questions on the topic of teleradiology from the current viewpoint].

A review on the theoretical challenges and potential risks of teleradiology is given. Based on the authors two years clinical experience and the current literature unsolved problems are discussed, which are to a smaller extent the technical implementation but much more the still missing regulation of various concomitant circumstances.

Computer Security↗

PubMed1997

[Virtual CT colonoscopy. Examination technique, limitations and perspectives].

Virtual CT-colonoscopy is a post-processing method which allows for reconstruction of inner bowel surface structures from helical CT datasets. The reconstructed images simulate the views which are known from fiberoptic endoscopy. Since colorectal cancer is the second main cause of death in USA and Europe today and since recent screening recommendations are often ignored by the public, a non-invasive or minimal-invasive procedure for colonic evaluation would offer some benefits. Virtual CT-colonoscopy generally involves three essential steps: patient preparation with cleansing of the bowel and administration of an air enema, helical CT-examination by using appropriate scan parameters, and interactive 3D rendering of the volume data-set. Although recent studies have demonstrated that polypoid lesions of about 5 mm size are well detectable and although virtual colonoscopy offers many advantages over fiberoptic endoscopy, some technical and clinical limitations must still be noted. Thus, the current inability of virtual colonoscopy to provide texture and color leads to problems in identifying flat lesions; the presence of retained or adherent fecal matter may result to false positive diagnosis and collapsed segments of bowel may cause problems as they cannot subsequently be evaluated during image reconstruction. Virtual endoscopy is still in its infancy and further technical and clinical developments are necessary. Virtual CT-colonoscopy may then prove to be equal or superior to colonoscopy in sensitivity and specificity for polyp detection and be able to reduce the number of unnecessary colonoscopic procedures.

Colonoscopes↗

PubMed1996

[Comparison and outcome of grade II and III acromioclavicular joint injuries].

Eighty-five patients with grade 2 or grade 3 sprains of the acromioclavicular (AC) joint were evaluated clinically and radiographically 32 months after injury. Group I included 34 patients with grade 2 sprains (Tossy II) and group II included 51 patients with grade 3 injuries (Tossy III). In group I, 15 patients were treated surgically (group Ia) and 19 patients were treated conservatively (group Ib), while in group II, 41 patients were treated surgically (group IIa) and 10 patients were treated conservatively (group IIb). At surgery open reduction and transarticular fixation of the AC joint with Kirschner wires was performed. Conservative treatment included the initial use of a sling or a knapsack bandage and early performance of range-of-motion exercises. Shoulder function was assessed according to the score devised by Constant and Murley. In both groups, 97 of 100 possible points (minimum 72, maximum 100) were obtained after conservative and after surgical treatment. Nine of 10 patients (90%) with grade 3 sprains (group IIb) had more pronounced displacement and increased mobility of the lateral end of the clavicle after conservative treatment. After surgery, dislocation and increased horizontal, mobility of the lateral end of the clavicle occurred in 18 (44%) of 41 patients with grade 3 sprains (group IIa P < 0.0001). However, these findings did not correlate with the functional outcome. At follow-up there was a significant increase in degenerative changes seen on radiographs (P < 0.035) in all patients. Again these findings did not correlate with the functional outcome. More degenerative radiological changes were observed in patients who had undergone surgery (P < 0.003). Patients with grade 2 sprains were more frequently restricted in sporting activity after surgery (P < 0.05). Patients with grade 3 sprains who were treated surgically complained of pain more frequently (P < 0.01), and they returned to work later than patients who were treated conservatively after grade 3 sprains. An additional rehabilitation program guided by a physiotherapist seemed to have no impact on the functional outcome. A total of 56 patients were treated by surgery. Among these patients 11 complications occurred, requiring five additional surgical procedures. Among 29 conservatively treated patients, only in 1 patient did subacromially located arthritic changes of the AC joint have to be removed.

Acromioclavicular Joint↗

PubMed1996

[The smart-scan procedure of spiral computed tomography. A new method for dose reduction].

PURPOSE: In this article a new method - the Smart-Scan-Technique - for dose reduction during spiral computed tomography is described. This technique allows a dynamical adaptation of the tube current according to the measured local density structure form and absorption values of the object of interest. Its clinical applicability for dose reduction is investigated. In addition, changes in image quality are evaluated. METHODS: Specially designed, water filled plexiglas-phantoms, an Alderson-Rando phantom, and 20 patients were used to simulate possible measures of patients within the thoracic and abdominal region. For those two regions the dose reduction, the modulation transfer function, and the pixel noise were measured. RESULTS: Depending on patient geometry dose reduction up to 20% could be achieved with the Smart-Scan-Technique. This technique also enabled a decrease of the modulation transfer function and an increase of the pixel noise by 8%. CONCLUSION: Relevant dose reductions can be achieved by applying the Smart-Scan-Technique in spiral computed tomography.

Absorption↗

PubMed1996

[Establishment of an emergency CT service by means of teleradiology].

UNLABELLED: The teleradiological connection between the University Hospital in Innsbruck, Tyrol, and the Regional Hospital in Zwettl, Lower Austria, is presented as an example of a routine online connection of two helical CT systems. PURPOSE: To establish a practicable and cost-efficient emergency CT service in a remote hospital during night time and on weekends. MATERIAL AND METHODS: Online connection of a GE HiSpeed Advantage-Spiral-CT and a GE Prospeed-Spiral-CT via two Sun SPARC 10 work stations and ISDN. RESULTS: The transmission of 121 CT data sets from 116 patients revealed a sufficiently fast average transmission time of 15 (6-53) minutes and average transmission costs of DM 9.00 per examination. The system was technically reliable, cost-efficient and practicable in clinical routine application. CONCLUSIONS: Teleradiology enables remote hospitals to provide an emergency CT service even if there is no radiological specialist available outside office hours. Thus time-consuming and cost-intensive patient transfers and delay of therapy can be reduced.

Austria↗

PubMed1996

[Dose reduction in computerized tomography with a new scan procedure].

A new investigation technique in computed tomography--the Smart Scan process--and the associated reduction in tube current are discussed. In addition, the reduced dosage values resulting from the reduced current values are compared with those of a standard measurement and image characteristics such as picture unit noise are evaluated. By means of three special water phantoms with dimensions corresponding to those of actual patient geometries and a pool of 183 patients, the Smart Scan process was tested by the control algorithm implemented on a spiral computer tomograph. The dosage values with and without the Smart Scan being activated were determined. Dosage reductions of up to 18% can be realized with this new examination technique. In particular, patients with transverse oval head profiles will benefit from this modality.

Adolescent↗

PubMed1995

Management of spontaneous extramedullary spinal haematomas: results in eight patients after MRI diagnosis and surgical decompression.

Spinal cord compression due to extradural and subdural haemorrhage is a neurosurgical emergency. Differences in clinical presentation in relation to localisation of the haematoma, value of MRI as a diagnostic tool, surgical treatment, and prognosis were investigated in a retrospective case series of eight patients with extradural (n = four) and subdural (n = four) haematomas. Results of MRI were compared with operative findings and proved to be of high sensitivity in defining the type of bleeding and delineating craniocaudal extension and ventrodorsal location. Surgical treatment by decompressive laminectomy, haematoma evacuation, and postoperative high dose corticosteroids resulted in resolution of symptoms in five patients and improvement in the clinical situation in two patients. One patient with a chronic subdural haematoma had a second operation because of arachnoidal adhesions. One patient presented with a complete cord transection syndrome due to an acute subdural haematoma and remained paraplegic. It is concluded that prompt, reliable, and non-invasive diagnosis by MRI leads to efficient surgical treatment and a favourable outcome in this rare condition.

Adult↗

PubMed1994

[Magnetic resonance tomography in epidural and subdural spinal hematoma].

Epidural and subdural spinal hematomas were previously diagnosed by myelography and computed tomography (CT). Recent reports indicate that noninvasive detection is possible with magnetic resonance imaging. We report on nine patients who were investigated by magnetic resonance imaging (MRI) prior to surgery for epidural and subdural spinal hematoma. The MR examinations were performed on 1.5-T and 1-T units. We used surface coils and employed T1-, PD- and T2-weighted spin echo sequences and a T2*-weighted gradient echo sequence. CT was available in four patients and myelography in two patients. Surgical correlation was available in all patients. The hematomas were located in the cervical spine (n = 2), thoracic spine (n = 6) and lumbar spine (n = 2). They were epidural in five patients and subdural in four. Blinded reading correctly identified all five epidural hematomas and three of the subdural hematomas; one subdural hematoma was misjudged as epidural. Peracute hematomas (< 24 h) in three patients appeared isointense or slightly hyperintense on T1-weighted images and had mixed signal intensity on T2- and T2*-weighted images. Acute hematomas (1-3 days) in four patients were also isointense on T1-weighted images but were more hypointense on T2- and T2*-weighted images. Chronic hematomas in two patients (7 days and 14 days) were hyperintense on all sequences. Differentiation between epi- and subdural hematomas required transverse T2*-weighted gradient echo sequences. Our results underline that MRI at 1 and 1.5 T is capable of identifying epidural and subdural spinal hematoma in the acute and peracute stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMed1994

[Diagnosis of the ulnocarpal complex in MRI cineradiography].

73 patients with persistent ulnar wrist pain of undetermined origin were examined by Magnetic Resonance Imaging (MRI). A series of 15 coronal slices was acquired using a T2* weighted gradient echo sequence. With repetitive measurement of those three slices that showed the triangular fibrocartilage complex (TFCC) best, the carpus was imaged 12 times during radial-ulnar deviation in increments of five degrees. The single images were combined according to their slice positions and continuously displayed on an image workstation, allowing for kinematic evaluation. Three different types of impingement of the TFCC were identified.

Adolescent↗