Biomedical subjects

A Gahleitner

Publications and source records attributed to A Gahleitner.

31 records · Page 2Linked to original sources

PubMed1999

[Occult fractures of the wrist joint: high resolution image magnification roentgen versus MRI].

PURPOSE: To compare the diagnostic value of high definition macroradiography and MRI in patients with the suspicion of occult wrist fractures. MATERIALS AND METHODS: In a prospective study, 23 patients with clinically suspected wrist fractures and normal initial plain radiographs underwent high resolution macroradiography and MR imaging shortly after trauma. Macroradiographs were taken with a microfocus tube using an anode of 0.03-0.3 mm providing a 4x magnification of the wrist, which was obtained in 4 projections. MR images were performed on a 1.0 T MR unit in coronal planes using T1 weighted SE, T2.-weighted 3D GE, and Turbo-STIR sequences. Follow-up radiographs after 6 weeks were used to confirm the diagnosis of a primary occult wrist fracture. RESULTS: Macroradiography depicted 5 wrist fractures: 4 fractures of the scaphoid bone and 1 fracture of the capitate bone. MRI demonstrated 11 fractures (one of them false-positive): 9 fractures of the scaphoid bone and two fractures of the capitate bone. Using macroradiography, the sensitivity for the detection of occult fractures of the wrist was 50% with a specificity of 100%, using MRI the sensitivity was 100% with a specificity of 92%. CONCLUSION: MRI seems to be superior to high resolution macroradiography in the detection of occult scaphoid fractures and thus is recommended in the management of patients with clinically suspected scaphoid fractures not evident on initial plain films.

Adolescent↗

PubMed1999

Dental vertical root fractures: value of CT in detection.

PURPOSE: To determine the value of computed tomography (CT) in the diagnosis of dental vertical root fractures relative to the value of conventional dental radiography. MATERIALS AND METHODS: Thirty-seven patients with 42 teeth in which vertical root fracture was clinically suspected underwent dental radiography and axial CT. Two radiologists evaluated the images independently and by consensus for a fracture line. The results were compared with intraoperative findings. RESULTS: Twenty-eight of the 42 teeth were proved intraoperatively to be fractured. The sensitivity and specificity averaged for the two reviewers in the assessment of vertical fractures were 23% and 70%, respectively, with dental radiography and 100% and 100%, respectively, with CT. Consensus reading showed sensitivities of 25% for dental radiography and 75% for CT. Eight (reviewer A) or nine (reviewer B) false-negative CT findings were encountered in cases in which metallic artifacts obscured parts of the root and in cases in which the root was very small in diameter. Interobserver agreement was 95% for dental radiography and 93% for CT. CONCLUSION: CT is superior to dental radiography in the detection of dental vertical root fractures.

Adult↗

PubMed1999

Dry versus conventional laser imagers: film properties and image quality.

The authors compared image quality and stability with a dry laser imager versus a conventional wet laser imager. Hard copies of 56 magnetic resonance imaging and computed tomographic studies were analyzed for gray-scale distribution and temperature stability. Results with the dry laser imager did not reach the quality of results with a wet laser imager, but the performance and ecologic criteria were sufficient to make use of this technique advantageous.

Calibration↗

PubMed1999

Osteometry of the mandible performed using dental MR imaging.

BACKGROUND AND PURPOSE: On cross-sectional and panoramic reformatted images from axial (dental) CT scans of the mandible it may be difficult to identify the inferior alveolar neurovascular bundle (IANB) in patients lacking a clear-cut bony delimitation of the mandibular canal. Dental MR images are comparable to dental CT scans, which directly show the IANB; however, measurements of length may not be reliable owing to susceptibility artifacts and field inhomogeneities in the oral cavity. Therefore, the accuracy of length measurements on dental MR images was compared with that on dental CT scans and direct osteometry. METHODS: Dental T1-weighted MR imaging using a high-resolution turbo gradient-echo sequence and dental CT were performed in six anatomic specimens. The axial scans were reformatted as panoramic and cross-sectional reconstructions on a workstation and characteristic cross sections were obtained from all mandibles. The longest axis in the bucco-lingual and apico-basal directions, the distances from the top of the mandibular canal to the top of the alveolar ridge and from the bottom of the mandibular canal to the base of the mandible, and the diameter of the bone cortex at the alveolar ridge were measured with direct osteometry on the cross sections and compared with measurements on corresponding MR and CT reformatted images. RESULTS: The correlation between direct osteometry and dental MR and CT was strong, except for the bone cortex diameter at the top of the alveolar ridge, where only a moderate correlation was found. Means of comparable length measurements were not significantly different among the three methods. CONCLUSION: The accuracy of length measurements in the jaw bones obtained using dental MR is comparable to that of dental CT and is not significantly different from direct osteometry. Thus, dental MR is a potential alternative to CT for dental imaging.

Alveolar Process↗

PubMed1998

[Monitor assessment of digitalized and post-processed portal films compared to conventional films presented on a light box].

PURPOSE: Judgement of image quality and detail recognition of digitized and post-processed portal films presented on a computer monitor compared to the present standard, conventional portal films presented on a light box. MATERIALS AND METHODS: Conventional portal films of 3 different tumor sites (10 pelvis, 10 cranium, 10 vertebral column) were presented to a panel of 8 observers in 3 different matters: conventional film presented on a light box (Conv), digitized post-processed images (Dig-1) and digitized post-processed images (Dig-2) presented on a high resolution computer monitor. Subjective judgement of image quality, detailed recognition and time requirement of conventional films compared to monitor presentation were evaluated using a 5-scaled questionnaire (from 1 = much better to 5 = much worse). Furthermore the observers had to point out predefined anatomical bony structure on the conventional films (Conv) as well as on the digitized post-processed images (Dig-2). Standard deviations of the landmark outlined by 10 different observers were used as a criterion of objective detail recognition (Figure 1). RESULTS: Image quality of digitized post-processed images presented on the computer monitor was judged statistical significant better than that of conventional films (pelvis 78%, vertebral column 62%, cranium 45% better) (Figure 3). Similar results were found for comparison of detail recognition: digitized post-processed images were scored better for pelvis in 81%, for vertebral column in 57%, for cranium in 40% (Figure 4, Table 1). Most benefit from portal film enhancement was found for pelvic images, where portal films are known to be of poor image quality (Figure 2). In contrast image quality of non-processed digital images compared to conventional films was graded worse (pelvis 69%, vertebral column 53%, cranium 71% worse) (Figure 4). Digital post-processed images were especially for the pelvis judged to require less time (pelvis 68%, vertebral column 26%, cranium 8% less time requirement) (figure 5). For the pelvis a statistical significant decrease of standard deviations was found for Dig-2 compared to conventional films, indicating an objective increase of image quality and detailed recognition (Table 2). In case of vertebral column and cranium no significant differences were evaluated (Table 3). CONCLUSIONS: Digitized enhanced portal films presented on a computer monitor resulted in a quicker assessment and equal to better image quality as well as detail recognition compared to conventional films. Non-processed digitized images were judged to be of less image quality.

Data Display↗

PubMed1998

Differentiation of benign and malignant tumors of the parotid gland: value of pulsed Doppler and color Doppler sonography.

To establish criteria for the differentiation of benign and malignant tumors of the parotid gland using color Doppler sonography (CDS) and pulsed Doppler sonography (PDS) we examined 37 patients with parotid tumors by gray-scale ultrasound, CDS, and PDS. Tumor vascularization displayed by CDS was graded subjectively on a 4-point scale (0 = no vascularization, 3 = high vascularization). From the Doppler spectrum, the highest systolic peak flow velocity, the resistive index (RI), and the pulsatility index (PI) were calculated. There were 11 malignant and 26 benign tumors. Tumor vascularization by CDS was grade 0 or 1 in 88.5% of benign lesions, whereas it was grade 2 or 3 in 82% of malignant lesions (P < 0.0001). The highest systolic peak flow velocity was statistically significantly higher in malignant lesions than in benign lesions. Using a threshold systolic peak flow velocity of 25 cm/s, sensitivity was 72% and specificity was 88% for the detection of a malignant tumor. Evaluation of tumor vascularization by CDS and PDS cannot differentiate between benign and malignant parotid tumors with certainty. However, high vascularization and high systolic peak flow velocity in tumor vessels should raise the suspicion of malignancy, even if tumor morphology on gray-scale sonography indicates a benign lesion.

Adenolymphoma↗

PubMed1998

Localization of the mandibular neurovascular bundle using dental magnetic resonance imaging.

OBJECTIVE: To assess the reliability of a commercially available 3D-MPR MRI program for the jaws for imaging the mandibular neurovascular bundle. METHODS: A gradient echo sequence (TR: 49 ms/TE: 6.3 ms/flip angle: 25 degrees/excitations: 3) with a spectral fat suppression pre-impulse and a voxel size of 0.9 x 0.9 x 0.8 mm was designed. Cross-sectional and panoramic reconstruction of the whole mandible were performed from the axial scans using Easy Vision (Philips, Best, The Netherlands) software package. The ability of differentiate the mandibular neurovascular bundle was assessed in 11 patients. RESULTS: The mandibular neurovascular bundle was clearly visualized in all cases. CONCLUSION: Dental MRI is a possible alternative to plain films or CT for patients requiring surgery near the mandibular canal.

Anatomy, Cross-Sectional↗

PubMed1998

[Dental magnetic resonance tomography (dental MRI) as a method for imaging maxillo-mandibular tooth retention structures].

PURPOSE: To establish a new method for dental imaging using magnetic resonance tomography named Dental-MRT and to demonstrate its usefulness in diagnosing dentogen pathologies of the mandible and maxilla. METHODS: Seven healthy volunteers, three patients with pulpitis, two patients with dentigerous cysts, two patients after tooth transplantation, and three patients with atrophic mandibles have been evaluated. Optimized axial T1- and T2-weighted gradient echo and spin echo sequences in 2D and 3D technique have been established to perform studies of the jaws. The acquired images were reconstructed with a standard dental software package on a work-station as panorama and cross-sectional views of the mandible or maxilla. RESULTS: The entire maxillo-mandibular bone, teeth, dental pulp, and the content of the mandibular canal were well depicted. Patients with pulpitis demonstrate bone marrow edema in the periapical region. Dentigerous cysts and their relation to the surrounding structures are clearly shown. After contrast media administration marked enhancement of the dental pulp can be demonstrated. CONCLUSION: Dental-MRT promises to provide a new tool for visualization and detection of dental diseases.

Adolescent↗

PubMed1995

[MR-pool: the "Vienna blend". An interactive computer-assisted teaching system for MRI].

Advances in the field of computer technology have facilitated the development of computer-assisted instruction. In this paper we present an interactive computer-based MR teaching system for education in radiology. Our program contains 120 teaching files. Various MR sequences can be displayed and compared to conventional X-ray images, CT, angiography and scintigraphy. Using a text field, additional clinical and diagnostic hints are offered. This teaching file can be easily upgraded and distributed on CD-ROM. Furthermore, we compare computer-assisted teaching in general to other conventional instruction media.

Austria↗

PubMedDate not supplied

Dental MR tomography of the mandible.

Imaging of the jaw bones is routinely achieved by conventional X-ray tomography or CT. In this study a new imaging procedure (dental MR tomography) is introduced. Five subjects were positioned in the standard neck coil of a 1.0 T MR scanner, and T1- and T2-weighted imaging of the mandible was performed in the axial plane. After the examination, the data were reconstructed as panorama and cross-sectional images using a software package for dental imaging on a workstation. The neurovascular bundle within the mandibular canal (MC), its relation to the teeth, and the pulp chambers of the teeth were demonstrated excellently in all cases. Edema and reactive hypervascularization due to an inflammatory process were also well visible. Dental MR tomography could become a good alternative to X-ray-based imaging modalities of the jaw bones by additionally offering the advantage of directly imaging the neurovascular bundle within the MC. Furthermore, administration of contrast agent for differentiation of pathological alterations is possible.

Adult↗

PubMedDate not supplied

Atypical appearance of elastofibroma dorsi on MRI: case reports and review of the literature.

Three patients with histologically proven elastofibroma dorsi underwent MRI, using T1-weighted, T2-weighted, STIR (short inversion time inversion recovery), and contrast-enhanced SE sequences. All lesions typically displayed low signal intensity masses interspersed with areas of high signal intensity on T1- and T2-weighted SE images. Contrary to prior reports, two patients showed marked enhancement of the mass after administration of Gd-DTPA. Although the characteristic signal intensity on conventional T1- and T2-weighted images may lead to the early diagnosis of this rare tumor, radiologists should be aware that marked contrast enhancement may be representative in elastofibroma dorsi.

Female↗

PubMedDate not supplied

Assessment of the blood supply to the mental region for reduction of bleeding complications during implant surgery in the interforaminal region.

Several life-threatening complications caused by hemorrhage that can occur during the placement of dental implants in the mandibular interforaminal region have been described in the literature. The aim of this study was to assess the vascular supply to this region and delineate the relative contribution and importance of the sublingual artery versus the submental artery. Thirty-four human cadavers were dissected. Special attention was directed to the presence of a branch of the submental artery that perforates the mylohyoid muscle and thus participates in the blood supply to the floor of the mouth together with the sublingual artery. A sublingual artery was found in 71% of the specimens. A large branch of the submental artery perforating the mylohyoid muscle was found in 41% of the specimens. The point of perforation was located an average of 31 mm posterior to the menton. The high risk of injuring the vessels of the floor of the mouth can be explained by the close vicinity of these vessels to the mandibular lingual cortical plate. To prevent complications in cases of unclear anatomic identification of the fossa sublingualis, preoperative lingual probing or elevation of the periosteum of the lingual aspect of the mandible is necessary. An alternative diagnostic procedure is precise preoperative noninvasive imaging (eg, computed tomography).

Aged↗

PubMedDate not supplied

Computed tomographic diagnosis and localization of bone canals in the mandibular interforaminal region for prevention of bleeding complications during implant surgery.

In this study, computed tomograms (CTs) of 70 patients were examined for visible vascular canals in the mandible as well as for their localization, incidence, diameter, and content. All patients examined showed at least 1 lingual perforating bone canal in the mandible. Since such vascular canals are encountered regularly, routine CT examination is recommended prior to implant surgery to help avoid severe bleeding complications during the placement of implants in the interforaminal region.

Adolescent↗