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M Heller

Publications and source records attributed to M Heller.

At least 127 records · Page 7Linked to original sources
PubMed1999

[Quantitative ultrasound. State of the art 1999].

In recent years Quantitative Ultrasound (QUS) approaches have increasingly been used for the assessment of osteoporosis. The development of new technologies has accelerated, and today a number of different devices are commercially available. For a balanced evaluation of the approaches one needs to recognise two issues: There are different applications for QUS, and there are different QUS approaches and devices. Regarding the applications, today the main area for use of QUS approaches is the assessment of a fracture risk. For use in monitoring and diagnosis, further advances and studies are required. Regarding the various approaches, one needs to recognise the differences between the measurement parameters Speed Of Sound (SOS) and Broadband Ultrasound Attenuation (BUA), the different measurement sites and the different technologies employed. Moreover, some of the earlier devices are very well validated whereas newer machines may feature more advanced technology--which, however, needs to be tested and validated. Whatever the choice of a device will be, adequate and regularly performed measures for quality assurance and in-depth knowledge on the general and device specific limitations of the approach are of substantial importance. When used appropriately, QUS devices can play an important role in the assessment of osteoporosis.

Humans↗
PubMed1999

MR imaging of musculoskeletal trauma to the pelvis and the lower limb.

Magnetic resonance imaging can be used in the trauma setting to detect fractures and associated soft tissue injuries of the musculoskeletal system. Magnetic resonance imaging complements plain radiography and CT for evaluating cancellous bone, cartilage and growth-plate injuries, and intra- and extraarticular supporting soft tissue structures. This review outlines typical applications and imaging consideration for injuries of the pelvis and lower extremity.

Bone and Bones↗
PubMed1999

Kinematic CT and MR imaging of the patellofemoral joint.

Anterior knee pain is a frequently encountered orthopedic symptom and is often associated with patellofemoral malalignment, which may cause chondromalacia of the patella. The difficulty in determining the patellar position between 0 degrees and 30 degrees of knee flexion with a conventional axial radiographic examination is well known. The introduction of computed tomography (CT) and magnetic resonance (MR) imaging for the diagnosis of knee joint abnormalities has enabled assessment of the patellar position in this critical range. More recently, emphasis has been placed on dynamic visualization of patellar motion to detect an abnormal tracking pattern. The important influence of the quadriceps muscle on the patellar tracking pattern is well known and has been examined during active knee extension by the use of ultrafast CT, and motion-triggered and ultrafast MR imaging. This article provides an overview of the current status of kinematic CT and MR imaging in the diagnosis of patellofemoral alignment, its clinical implications, and future directions.

Arthralgia↗
PubMed1999

Optimized preoperative planning of calcaneal fractures using spiral computed tomography.

The aim of this study was the evaluation of spiral-CT examinations in preoperative planning of calcaneal fractures supported by 3D reconstructions after electronic disarticulation. We examined 45 patients with 47 calcaneal fractures with diagnostic spiral-CT examinations in a prospective study. In addition to the conventional axial slices and sagittal reconstructions, 3D reconstructions prior to and after electronic disarticulation were performed and rated by orthopaedic surgeons and radiologists. The following diagnostic criteria were rated: involvement of articular facets, number of fragments and hindfoot deformities. Axial slices were considered to be the gold standard, because not all patients underwent surgical treatment. Axial slices showed involvement of 90 articular facets (100 %). Three-dimensional reformations after electronic disarticulation depicted 82 fractures (82 of 90, 91 %), sagittal reconstructions 63 fractures (63 of 90, 70 %). Three-dimensional reconstructions without electronic disarticulation showed five fractures (5 of 90, 5.5 %). The number of fragments was demonstrated best on sagittal reconstructions (two, three or four fragments); five fragments were diagnosed best on axial slices, and 3D reconstruction without electronic disarticulation showed only a very small number of fragments, due to overlaying bones. Hindfoot deformities (lateralisation, varus deformation, shortening) were demonstrated best on axial slices, except in terms of showing height reduction, which was demonstrated better on sagittal and 3D reconstructions. Three-dimensional reconstructions after electronic disarticulation support a clear understanding of the 3D position of the fragments and of their displacement in comparison with 3D reconstruction without electronic disarticulation, which is essential for an effective surgical reduction. Due to the potential manipulation of surface-oriented 3D reconstructions, regardless of whether electronic disarticulation is used, this imaging technique should not be considered in an isolated framework. Three-dimensional images without electronic disarticulation are superfluous in any case.

Calcaneus↗
PubMed1999

Late aneurysm formation in a femoro-popliteal polytetrafluoroethylene graft.

Since improvement in the material, true aneurysms and pseudoaneurysm formations have become relatively rare complications after femoro-popliteal reconstruction with polytetrafluoroethylene (PTFE) grafts. We report a case of late graft rupture and pseudoaneurysm formation within the straight femoral part of a femoro-popliteal bypass with reinforced (PTFE-wrapped) Gore-Tex graft. The rupture occurred 7 years after implantation without history of direct traumatization. Intraoperatively the whole bypass showed macro- and microscopically visible deterioration of the wall with almost complete disruption at the site of the aneurysm. The graft had to be replaced completely. In conclusion, we recommend continuous long-term follow-up of these patients preferably with duplex ultrasonography.

Aneurysm, False↗
PubMed1999

Pure ocular cicatricial pemphigoid. A distinct immunopathologic subset of cicatricial pemphigoid.

OBJECTIVE: To determine whether ocular cicatricial pemphigoid (OCP) may represent a distinct immunopathologic disease when it is pure ocular cicatricial pemphigoid (POCP) (e.g., only confined to the conjunctiva) or when it is associated with skin or extraocular mucous membrane lesions or both (OCP+). DESIGN: Prospective, immunologic, and immunopathologic study with special emphasis on direct immunoelectron microscopy. PARTICIPANTS: Six patients with POCP and seven patients with OCP+. INTERVENTION: After informed consent was obtained, a conjunctival biopsy was performed in all patients. Skin and extraocular mucosa biopsy specimens were harvested in selected cases only. MAIN OUTCOME MEASURES: Results of direct immunofluorescence and direct immunoelectron microscopy without freezing on conjunctival and skin biopsy specimens, indirect immunofluorescence, and Western immunoblotting analysis were analyzed. RESULTS: Results of direct immunoelectron microscopic examination of the conjunctiva showed the presence of immune deposits in the upper lamina lucida of the basement membrane zone in the six patients with POCP, whereas the immune reactants were located in the lower part of the lamina lucida and in the lamina densa of the basement membrane zone (conjunctiva, buccal mucosa, and skin) in the seven patients with OCP+. Direct immunofluorescence was positive in the biopsy specimens of three patients with POCP (50%) and the seven patients with OCP+ (100%). Results of indirect immunofluorescence study showed circulating autoantibody levels only in two patients with OCP+, and results of Western immunoblot analysis were negative. CONCLUSIONS: Results of direct immunoelectron microscopic examination of the conjunctiva support the hypothesis that POCP may be a disease entity distinct from mucocutaneous cicatricial pemphigoid.

Aged↗
PubMed1999

Homonuclear uncoupled 1H-spectroscopy of the human brain using weighted accumulation schemes.

Homonuclear uncoupled H-spectroscopy based on 2-dimensional (2D) J-resolved spectroscopy is a well suited technique for the assessment of J-coupled metabolite resonances. In comparison with 1-dimensional H-spectroscopy this technique largely reduces problems due to spectral overlap between low molecular weight metabolite resonances and superimposed broad macromolecule resonances, as well as overlap between adjacent multiplets. Usually, 2D J-resolved spectroscopic data were acquired using a constant number of accumulations for each of the various echo times. In contrast to this, a weighted accumulation scheme has been applied in this study, using an echo time dependent number of accumulations. The aims of this modification were to reduce the acquisition time and to improve the signal-to-noise ratio per unit acquisition time (SNRt). Four different sine-bell like accumulation schemes and a reference scheme using a constant number of accumulations have been applied on five normal volunteers. Localized spectra obtained from the parieto-occipital white matter were compared with regard to SNRt and linewidth. A reduction in acquisition time of 45%, related to the reference scheme, and an increase in SNRt of 25-30% were achieved using a sine-bell accumulation scheme in combination with a quarter sine-wave apodization of the short echo time data. Down to an acquisition time of 122 s no significant line broadening has been observed in comparison with the reference scheme.

Brain↗
PubMed1999

Impact of emergency medicine resident training in ultrasonography on ultrasound utilization.

Training programs in bedside ultrasound for emergency physicians often encounter considerable resistance, partly because of concern that the number of radiology-interpreted studies ordered from the ED may decrease. This study attempted to determine the effect of instituting an ED training program in ultrasound on the ordering of formal studies from a department of radiology. This retrospective, computer-assisted review compared all abdominal sonograms ordered from the ED of a busy community hospital in the 3 years before introduction of an ultrasound training program (1992 through 1994) with those ordered in the 2 years after the program's inception (1995, 1996). The number of formal studies significantly increased after institution of the training program, both in terms of absolute numbers (annual mean 181 v 95, P < .001) and as a percentage of all outpatient sonograms ordered at the institution (9.8% v 5.1%, P < .001). Introduction of a teaching program in emergency ultrasound appears to increase utilization of formal ultrasound services, at least during the training period.

Abdomen↗
PubMed1999

Studies on the influence of combined administration of ochratoxin A, fumonisin B1, deoxynivalenol and T2 toxin on immune and defence reactions in weaner pigs.

In weaners, combined administration of fumonisin, deoxynivalenol and T2 together with ochratoxin A in quantities expected to be present in feeds of central European origin resulted, as a rule, in changes identical to those observed after single administration of ochratoxin A. Such reactions were partly compensated. Synergistic amplification of immunosuppressive changes due to the simultaneous intake of these mycotoxins in low concentrations is not to be expected.

Animals↗
PubMed1999

Studies of the influence of ochratoxin A on immune and defence reactions in weaners.

Even in subtoxic amounts, the mycotoxin, ochratoxin A, produced immunomodulation in weaner pigs in a dose-dependent mode. In addition to increased counts of total leukocytes and neutrophils in the blood, reduced lymphocyte levels were observed. There was a striking increase in the counts of eosinophils and of apoptotic phagocytes. Functionally, there was a predominance of the production of reactive oxygen radicals in whole blood, reduced phagocytosis performance and reduced expression of a swine-specific surface marker (SWC1) on lymphocytes. In a few single experiments, clinical manifestations could be demonstrated. Lung clearance and the degree of severity of experimental pneumonia as well as cutaneous hypersensitization may be influenced by ochratoxin A.

Animals↗
PubMed1999

[The x-ray follow-up study of the cervical spine after anterior fusion with titanium disk implants].

PURPOSE: We examined the postoperative changes of the cervical spine after treatment of cervical nerve root compression with anterior cervical discectomy and fusion with a new titanium intervertebral disc. PATIENTS AND METHODS: 37 patients were examined prior to, as well as 4 days, 6 weeks, and 7 months after surgery. Lateral view X-rays and functional imaging were used to evaluate posture and mobility of the cervical spine, the position of the implants, and the reactions of adjacent bone structures. RESULTS: Implantation of the titanium disc led to post-operative distraction of the intervertebral space and slight lordosis. Within the first 6 months a slight loss of distraction and re-kyphosis due to impression of the implants into the vertebral end-plates were found in all patients. We noted partial infractions into the vertebral end-plates in 10/42 segments and slight mobility of the implants in 14/42 segments. Both groups of patients showed reactive spondylosis and local symptoms due to loosening of the implants. The pain subsided after onset of bone bridging and stable fixation of the loosened discs. CONCLUSIONS: The titanium intervertebral disc provides initial distraction of the fusion segments with partial recurrence of kyphosis during the subsequent course. Loosening of the implants with local symptoms can be evaluated with follow-up X-rays and functional imaging.

Adult↗
PubMed1999

[Rotational digital subtraction angiography of carotid bifurcation stenosis].

PURPOSE: A prospective study was designed to evaluate, whether multiplanar imaging with rotational digital subtraction angiography (R-DSA) could improve assessment of carotid artery bifurcation stenosis. PATIENTS AND METHODS: 45 patients with suspected stenosis of the ICA were examined with DSA in standard projections (0 degree-(45 degrees)-90 degrees) and additional R-DSA of each ICA from 0-90 degrees in 10 degrees steps. We compared imaging quality and degree of stenosis as well as exposure of the patients to radiation and contrast media. RESULTS: 79/82 R-DSA (96%) were suitable for evaluation of stenosis, 58/82 (70%) matched the quality standard of single projection DSA. Specificity and sensitivity of the R-DSA to diagnose high grade ACI stenosis were 100% and 94%, respectively. 7/79 R-DSA revealed a higher and 3/79 a lower degree of stenosis than the corresponding DSA. Regarding the degree of stenosis there was no significant difference between the two modalities (p > 0.05), but R-DSA detected 4 stenoses greater than 60% that were estimated to be lower than 60% by DSA. Radiation dose for R-DSA was equivalent to one DSA run (170 cGycm2). The average amount of contrast media (25 ml) was slightly higher than for 2-3 single-projection DSA (19.8 ml). CONCLUSIONS: R-DSA provides high quality imaging of the carotid bifurcation with multiplanar projections facilitating exact grading of vessel stenosis. The number of cases (n = 2) is to small to judge the value of R-DSA as to (tandem-) stenosis of the distal ICA. Still, diagnostic value and low radiation exposure justify the use of R-DSA as additional series to standard protocols.

Adult↗
PubMed1999

[MR arthrography of the labrum acetabulare--a radiological-anatomical correlation in 20 cadaveric hips].

PURPOSE: To investigate frequency of acetabular labral lesions in elderly hip joints, and to determine sensitivity and specificity of MR arthrography (MRa) for the detection of these abnormalities. MATERIALS AND METHODS: Twenty cadaveric hip joints were examined by MRa. For MRa, 15 ml of a solution of iodinated contrast solution (Solutrast 300) and Gd-DTPA (100:1) were injected under fluoroscopic guidance. MR imaging was performed on a 1.5 T MR scanner (Vision, Siemens; FOV 16 cm, matrix 256 x 256, fat-suppressed 3D-FLASH). Multiplanar image reconstructions were done perpendicular to the acetabulum in the oblique-coronal, oblique-axial, and radial planes. The labral specimens were examined macroscopically. RESULTS: In 12/20 hips (60%), a labral lesion was found on pathologic examination. In 7 specimens, the labrum was partially or completely detached in the weight-bearing superior region. One flap-like variant of the labrum was seen; in 4 hip joints, the labrum was degenerated (one cystic degeneration). Pathologic findings were confirmed by MRa in 8/12 specimens (sensitivity 67%). All degenerated labra were correctly diagnosed on MRa. Three small labral detachments and the flap-like variant were misinterpreted as being normal. There were no false positive findings (specificity 100%). The accuracy was 80%. Labral lesions were seen in 6/8 and in 6/12 of hips with and without osteoarthritis, respectively. CONCLUSION: MRa is well suited to delineate the acetabular labrum and to diagnose labral abnormalities. Detection of small labral detachments and anatomic variants is difficult and requires some experience. Labral lesions are correlated to osteoarthritis of the hip, but may be frequently seen in the elderly without underlying osteoarthritis.

Acetabulum↗
PubMed1999

[In vitro comparison of a size 6F and 8F high-speed rotational catheter for mechanical thrombus fragmentation].

PURPOSE: In vitro comparison of the 6F and 8F Amplatz thrombectomy device (ATD) for treatment of thrombotically occluded vessels in a flow-model. MATERIALS AND METHODS: Thrombectomy of clots from porcine blood was performed with either a 6F or an 8F Amplatz thrombectomy device (ATD) in a flow-model simulating a superficial femoral artery circuit (n = 40; 7.5 g: 7 mm diameter; 4.5 g: 5 mm diameter). Emboli caused during thrombectomy were determined in a three-step filter array (10 microns-1000 microns). RESULTS: Thrombectomy was successful in all cases. In 5 mm/7 mm lumen time for thrombectomy was measured from 47 s/56s (8F) to 86 s/107 s (p < 0.01) (6F). Remaining thrombus weighted in 5 mm/7 mm lumen 0.04 g/-0.02 g (8F) and 0.05 g/-0.02 g (6F). Overall weight emboli determined for 1000 microns, 100 microns and 10 microns size and percentage of emboli related to original thrombus weight measured 0.23 g/4.96% (8F, 5 mm), 0.2 g/4.36% (6F, 5 mm), 0.08 g/1.13% (8F, 7 mm). and 0.09 g/1.18% (6F, 7 mm). CONCLUSIONS: In vitro, the 6F ATD is in "vessels" with 5 mm and 7 mm diameter as effective as the 8F version. Particle embolization in flow-circuit was similar with both devices, although the 6F ATD requires a longer time for thrombectomy in vessel with larger diameter.

Animals↗
PubMed1999

In vitro effectiveness study for hydrodynamic thrombectomy devices of the second generation.

RATIONALE AND OBJECTIVES: To determine the efficacy of clot removal and the amount of applied saline and aspirated fluid and to compare procedure-related particle embolization for the hydrodynamic thrombectomy devices the LF 140 Angiojet (LF 140), the double-lumen Hydrolyser (double HL), and the triple-lumen Hydrolyser (triple HL) in an in vitro flow model. METHODS: Thrombectomy of clots (n = 42) from 7-day-old porcine blood (9.8 g) was performed with the LF 140, the double HL, and the triple HL in a flow model (flow 1 L/min) made of silicone tubes (7 mm inner tube diameter). All catheters were used according to the manufacturer's recommendations. RESULTS: Mean time of thrombectomy ranged from 20 seconds (triple HL) to 58 seconds (LF 140, P < 0.05). Only for the triple HL was remaining thrombus found within the tubes (41 mg). None of the tested devices worked isovolumetrically: the mean ratio of applied saline and aspirated fluid for the devices ranged from 0.79 (triple HL) to 0.89 (double HL, P < 0.05). Mean embolus weight and percentage of embolism from original thrombus were 675 mg/6.7% (LF 140, P < 0.05), 38 mg/0.4% (double HL), and 26 mg/0.3% (triple HL). CONCLUSIONS: Thrombectomy time and embolus weight depend on the device chosen. The ratio of applied to aspirated fluid, indicating the capability to work nearly isovolumetrically, is acceptable for all tested devices. In vitro, the triple HL seems to be the most appropriate device for rapid mechanical, hydrodynamic thrombectomy. Because of the high in vitro particle embolization rate, the LF 140 seems to be strictly limited to small-caliber vessels.

Animals↗
PubMed1999

Enhancement of in vitro effectiveness for hydrodynamic thrombectomy devices. Simultaneous high-pressure rt-PA application.

RATIONALE AND OBJECTIVES: To determine the efficacy of simultaneous high-pressure recombinant tissue plasminogen activator (rt-PA) application for clot removal and procedure-related peripheral particle embolization for the hydrodynamic thrombectomy devices LF 140 AngioJet (LF 140) and triplelumen Hydrolyser (triple HL) in an in vitro flow model. METHODS: Thrombectomy of clots (n = 47) from 5-day-old human blood (8.9-9.7 g) was performed with the LF 140 and the triple HL, each with and without simultaneous rt-PA (9.97-12.59 g) application in a flow model (flow 1 liter/min) made of silicone tubes (7 mm inner tube diameter). All catheters were used according to the manufacturer's recommendations. RESULTS: The triple HL revealed no statistically significant performance differences with additional rt-PA. For the LF 140, mean thrombectomy time ranged from 23.5 sec (with rt-PA) to 33.5 sec (P = 0.05). The ratio of peripheral embolus weight to thrombus weight was reduced from 2.12% to 0.46% (rt-PA; P = 0.05). None of the tested devices had an isovolumetric performance; the mean ratio of applied saline to aspirated fluid for the devices were different from one, ranging from 0.89 to 0.92 (rt-PA) for the triple HL and from 0.43 to 0.52 (rt-PA) for the LF 140. No significant differences for remaining thrombus within the tubes were found. CONCLUSIONS: Simultaneous rt-PA-enhanced hydrodynamic thrombectomy is feasible in vitro. This combination reduces the time for thrombectomy and procedure-related peripheral particle embolization for the LF 140. No effect could be demonstrated for the triple HL in an in vitro flow model. It remains unclear whether this procedure is effective in vivo. It seems likely that the incidence of fibrinolysis-associated complications may increase in vivo.

Humans↗
PubMed1999

Mechanical assistance for enhancement of in vitro effectiveness for hydrodynamic thrombectomy.

OBJECTIVE: To determine whether the efficacy for clot removal and procedure-related peripheral particle embolization for the hydrodynamic thrombectomy device CF 105 AngioJet (CF 105) can be enhanced with the use of guiding catheters and an occlusion balloon in an in-vitro flow model. METHODS: Thrombectomy of clots (n = 97) from 5-day-old human blood (range, 9.28-9.77 g) was performed with the CF 105 alone, with additional guide wires (CF 1050.014/0.018), with a 30 degree angled tip (CF 10530 degrees), with guiding catheters (CF 105MP/HS), and with an additional occlusion balloon (CF 105OB) in a flow model (flow 1 L/min) of silicone tubes (inner tube diameter, 7 mm). RESULTS: Mean thrombectomy time ranged from 28.71 seconds (CF 105OB) to 37.02 seconds (CF 10530 degrees). When a guide wire was used, the time for thrombectomy was not prolonged. None of the devices tested worked isovolumetrically. The ratio of applied saline and aspirated fluid (0.34) for CF 105 alone was significantly better than for CF 1050.014/0.018 (0.49/0.60; for both P < 0.001). Compared with CF 105 alone (273.16 mg), wall-adhesive thrombus was reduced significantly with CF 105MP (43.66 mg), CF 105HS (48.66 mg), and CF 10530 degrees (97.27 mg; P < 0.001 for all). Compared with the highest rate of embolism for CF 105 alone (4.62%), CF 105OB (2.50%; P < 0.001), CF 105HS (3.04%; P < 0.001), CF 105MP (3.49%; P < 0.001), and CF 105018 (3.64%; P < 0.001) produced better ratios. CONCLUSIONS: The use of guiding catheters and occlusion balloons is feasible to enhance hydrodynamic thrombectomy in vitro. This combination reduces procedure-related peripheral particle embolization and wall-adhesive thrombus during hydrodynamic thrombectomy. To avoid blood loss, the device should be used only with a 0.018" guide wire.

Adult↗