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P Hübsch

Publications and source records attributed to P Hübsch.

At least 19 recordsLinked to original sources
PubMed2000

Numerical investigation of fixed orthodontic brackets.

This paper presents the results of investigations into the mechanical behaviour of fixed orthodontic brackets. Special attention has been paid to the detailed modelling of the interface between the bracket base and an adhesive by which attachment is made to the tooth surface. Properties of this interface were taken as design parameters with the aim of investigating their influence on the stress field induced during bracket removal at the end of the treatment. Stress-strain analysis was performed using a finite element program developed in-house.

Dental Cements↗
PubMed1999

Differential diagnosis on ancient skeletal remains: conventional methods and novel application of the BSE-mode in SEM on a skull tumor of the early Bronze Age.

Tumor-like lesions on skeletal remains put relatively high demands on paleopathological diagnostic methods. In addition to conventional anthropological determination and non-invasive methods of macroscopical description and radiodiagnostic examination, bony lesions can be analyzed more accurately, but also more elaborately by light microscopy of invasive section preparations. In this study an irregular new bone formation on the excavated skull of a juvenile individual was also investigated by scanning electron microscopy (SEM). A cut-out block of the lesion was first observed in the secondary electron-mode (SE-mode), and then methylmethacrylate-embedded ground and polished sections were for the first time also evaluated in the back-scattered electron-mode (BSE-mode). Thereby, new insights into the bone structure and the development of this tumor-like lesion could be obtained which led to the diagnosis of a meningioma.

Adolescent↗
PubMed1998

Venous contrast fluid level in computed tomography.

OBJECTIVE: To evaluate the clinical significance of a venous contrast fluid level during computed tomography (CT). METHODS: An incidentally found contrast fluid level in the left internal jugular vein during CT in an otherwise healthy patient was the reason for investigation of this phenomenon. We collected data over a 4-year period at our institution and reviewed the case notes of seven patients exhibiting this CT finding. We also performed conventional radiography, CT, venography and colour-coded Doppler sonography to rule out an underlying pathology in those patients. Additional in-vitro CT studies were performed to define conditions of flow leading to a contrast fluid level. Flow dynamics in the internal jugular veins were studied in vivo by using colour-coded Doppler sonography in 20 normal volunteers. RESULTS: In addition to our first patient, we found seven patients with a venous contrast fluid level among a total of 58400 contrast-enhanced CT examinations performed in our institutions. The investigations were performed on various CT-units, with different scan protocols, injection rate, dose and manufacturer of non-ionic contrast agent. The contrast fluid level was encountered unilaterally in the left internal jugular vein in seven patients and in the inferior vena cava in one patient. All patients were free of symptoms and the outcome of all other examinations was unremarkable. In-vitro and in-vivo studies showed that pure contrast agent entering a vessel (in case of the internal jugular vein due to physiological flow and/or stasis) can produce a contrast fluid level. CONCLUSION: The occurrence of a venous contrast fluid level during contrast enhanced CT is an incidental finding of no pathological significance and need not initiate costly further examinations.

Adult↗
PubMed1998

Location of a VIPoma by iodine-123-vasoactive intestinal peptide scintigraphy.

A major problem in patients with small endocrine tumors is the difficulty in localizing the primary tumor site. Many endocrine tumors possess larger amounts of high affinity vasoactive intestinal peptide (VIP) binding sites compared with normal tissue or blood cells. We used radiolabeled VIP to localize the tumor site in a patient with Verner-Morrison syndrome (VMS). Under octreotide therapy, the VIP levels had declined in this patient, but a tumor site could not be detected by conventional techniques or by radiolabeled octreotide. However, using 123I-VIP, the tumor was detectable in the pancreatic tail. Surgical resection of the tumor was followed by complete remission of the VMS. Expression of VIP binding sites in the tumor was confirmed by a radioreceptor assay and showed cross-competition between VIP and octreotide. The identity of the VIP binding site in the tumor was analyzed by Northern blotting and revealed the expression of somatostatin receptor subtype 3, which binds both somatostatin-14 and VIP with higher affinity than octreotide. Iodine-123-VIP scintigraphy would be an effective tracer to identity the tumor site in VMS patients.

Adult↗
PubMed1997

Scarpa's fascia flap: anatomic studies and clinical application.

Fascia and fascia-subcutaneous flaps are thin, pliable, and well-vascularized tissue with aesthetic and functional advantages, particularly for the extremities and in the head and neck region. Although various donor sites have been used for these flaps, there is an occurrence of unsatisfactory donor-site defects that are often complicated by conspicuous, widened scars or alopecia. In addition, flap elevation is sometimes prolonged because of the demanding operative procedures as well as the impossibility of a two-team approach. In this anatomic and clinical study we present a new fascial flap that results in a minimal donor-site defect and a short and easy operative procedure. Scarpa's fascia, which can be used as both a free and a pedicled flap, is a well-defined single membranous sheet within the subcutaneous tissue layer at the lower abdominal wall. We studied its distribution, structure, and vascular supply in 27 fresh cadaver specimens. In addition, computed tomographic (CT) and ultrasound studies were performed in 13 healthy volunteers and in 3 cadavers before and after injection of diluted contrast material in the superficial epigastric artery. Finally, histologic examinations were done with hematoxylin and eosin or with reticulum and elastin. Our studies showed that Scarpa's fascia provides a thin, pliable, and well-vascularized flap pedicled on the superficial epigastric artery. After successful application of the Scarpa's fascia flap as a free flap in 3 patients and as a pedicled option in 1 patient, we can recommend this flap as a valuable tool for the reconstructive surgeon.

Abdominal Muscles↗
PubMed1996

123I-vasoactive intestinal peptide (VIP) receptor scanning: update of imaging results in patients with adenocarcinomas and endocrine tumors of the gastrointestinal tract.

Recent data suggest that functional receptors (R) for vasoactive intestinal peptide (VIP) are expressed on various tumor cells. The high-level expression of VIPR on tumor cells provided the basis for the successful use of 123I-labeled VIP for the in vivo localization of intestinal adenocarcinomas and endocrine tumors. We here report an update of our imaging results using 123I-VIP (150-200 MBg/1 microgram/patient) in 169 patients. In patients with pancreatic adenocarcinomas without liver metastases, the primary/recurrent tumor was visualized in 16 of 18 patients (89%) and liver metastases were imaged in 15 of 16 patients. In 11 of 12 patients with colorectal adenocarcinomas, the primary/recurrent tumor (92%) was imaged by 123I-VIP. Also, in 21 of 25 patients, liver metastases (84%); in 3 of 6 patients, lung metastases (50%); and in 4 of 5 patients, lymph-node metastases (80%) were imaged by 123I-VIP. In 10 of 10 patients with gastric adenocarcinomas, the primary/recurrent tumor; in 3 of 4 patients, liver metastases; and in 2 of 2 patients, lymph-node metastases were visualized by 123I-VIP. 123I-VIP localized primary intestinal carcinoid tumors in 15 of 17 patients (88%) and 8 of 10 primary insulinomas (80%). We conclude that the 123I-VIPR scintigraphy localizes intestinal adenocarcinomas and endocrine tumors as well as metastatic tumor sites.

Adenocarcinoma↗
PubMed1996

Bronchial wall thickness: appropriate window settings for thin-section CT and radiologic-anatomic correlation.

PURPOSE: To analyze the influence of computed tomographic (CT) window settings on bronchial wall thickness and to define appropriate window settings for its evaluation. MATERIALS AND METHODS: Three inflation-fixed lungs were scanned with a section thickness of 1.5 mm by using a high-spatial-frequency algorithm. Wall thickness in 10 bronchial specimens was measured with planimetry. Window centers were altered in a range of -200 to -900 HU and window widths in a range of 400-1,500 HU. Relative and absolute differences between CT and planimetric values were calculated. CT and planimetric measures were correlated. Inter- and intraobserver variabilities were determined. RESULTS: Window widths less than 1,000 HU resulted in a substantial overestimation of bronchial wall thickness, whereas widths greater than 1,400 HU resulted in an underestimation of bronchial wall thickness. There was no interaction between "width" and "center" regarding their influence on bronchial walls (F = 0.23; P = .99). Correlation between CT and planimetry was statistically significant (r = .85; P = .0001). Differences between the two observers were not statistically significant; results of the measurements of the two observers correlated well (r = .97; P = .001). CONCLUSION: Bronchial wall thickness on thin-section CT scans should be evaluated with window centers between -250 and -700 HU and with window widths greater than 1,000 HU. Other than window settings, notably window widths less than 1,000 HU, can lead to substantial artificial thickening of bronchial walls.

Adult↗
PubMed1995

Update: abdominal tuberculosis--unusual findings on CT.

To update our knowledge of abdominal tuberculosis as manifested on computed tomography (CT), we reviewed the CT scans of 12 patients with proven abdominal tuberculosis. The nature, range and extent of abdominal involvement was determined. The CT findings were compared to those reported in the literature. The aetiologic agent was Mycobacterium tuberculosis in all patients. One patient had an increased risk because of AIDS. In nine patients, tuberculosis was limited to the abdomen, and three patients had previously unknown thoracic tuberculous disease. Characteristic features in our patients included low density ascites and uncommon patterns of adenopathy. Findings reported to be typical in abdominal tuberculosis were present in only five of our 12 patients. Unusual findings in our patients included solitary and multiple pelvic, adrenal, splenic and hepatic lesions. In six of 12 patients, those findings mimicked malignancy. We conclude that knowledge and early recognition of these unusual manifestations of abdominal tuberculosis should help to optimize clinical management of the disease and avoid misdiagnosis.

Abdominal Pain↗
PubMed1995

Discrete lung involvement in systemic lupus erythematosus: CT assessment.

PURPOSE: To study the computed tomographic (CT) appearance of early lung involvement in systemic lupus erythematosus (SLE). MATERIALS AND METHODS: In a prospective study, 48 patients with serologically confirmed SLE but no prior clinical evidence of lung involvement underwent chest radiography, CT, and lung function tests. Radiographs and CT scans were compared, and CT scans were evaluated for signs suggestive of parenchymal and pleural disease. Extent and distribution of disease were determined. CT findings were correlated with clinical and functional data. RESULTS: Of 45 patients with normal chest radiographs, 17 (38%) had abnormal CT findings. Extent of disease was statistically significantly correlated with duration of clinical history (r = .93) and decreased single-breath diffusing capacity for carbon monoxide (r = .8) and ratio of forced expiratory volume in 1 second to forced vital capacity (r = .77). CONCLUSION: CT is superior to chest radiography for detection of functionally relevant pulmonary disease and is an important adjunct in early assessment of SLE.

Adult↗
PubMed1995

Automatic patient-instruction devices in thin-section CT of the thorax: impact on image quality.

PURPOSE: To determine what influence automatic patient-instruction (API) devices have on image quality of chest computed tomographic (CT) scans and whether the qualitative outcome justifies their routine use. MATERIALS AND METHODS: Thin-collimation CT scans of two age- and sex-matched groups of 64 patients each were evaluated prospectively for the presence of breathing artifacts and for concomitant deterioration of image quality. Breathing commands in group 1 were given with the API device and in group 2 with technologist-performed patient instruction. Cardiac motion artifacts were not evaluated. The frequency of scans repeated owing to breathing artifact was determined. RESULTS: Image quality was worse in group 1 compared with that of group 2. The percentage of scans repeated was higher with API (38%) than without API (16%). CONCLUSION: API devices cannot be recommended for thin-section CT of the thorax. The large number of scans that must be repeated leads to a considerable increase in patient irradiation, scanning time, and cost.

Adult↗
PubMed1995

Position of jugular oxygen saturation catheter in patients with head trauma: assessment by use of plain films.

OBJECTIVE: The purpose of this study was to establish a plain radiographic technique for the assessment of the position of a jugular oxygen saturation catheter in patients with head trauma. MATERIALS AND METHODS: In the experimental study, jugular oxygen saturation catheters were introduced into the internal jugular veins of four cadavers. Correct positioning of the catheter tips was monitored by CT. Concurrent anteroposterior radiographs of the skulls were obtained with the tubes angled in a transverse plane and in a sagittal plane at intervals of 5 degrees and within a total range of 70 degrees for each plane. Three radiologists judged the visibility of the catheter tips and measured the distance of the catheter tips to previously determined bony landmarks of the skull. Then, preliminary radiologic criteria for correct positioning of the catheters were defined. In the clinical study, we prospectively evaluated radiographs for 32 patients who received jugular oxygen saturation catheters. Eleven patients had digital radiographs done, and 21 patients had radiographs with a conventional screen film system done. Radiographs were analyzed for consistency of findings with the experimental results and for consistency of the suspected catheter position with laboratory data. RESULTS: Results of the cadaveric study showed that catheter position is best assessed on strict anteroposterior radiographs with the orbitomeatal-basal line perpendicular to the plane of the film. A correctly positioned catheter tip should lie cranial to a line extending from the atlantooccipital joint space and caudal to the lower margin of the orbit. The catheter tip also should lie cranial to a line connecting the tips of the mastoid processes, with a catheter tip-to-line distance averaging 20% of the overall distance between the tips of the mastoid processes. According to these criteria, the catheter was properly positioned in 26 of 32 patients. In three patients, the catheter obviously was improperly positioned. Catheter position was equivocal in three other patients; in two of these patients, the catheter was looped within the internal jugular vein. Whereas for all 26 patients with properly positioned catheters values for jugular venous oxygen saturation were congruent with other laboratory data, incongruent saturation values were recorded for five of the six patients with equivocally or obviously improperly positioned catheters. CONCLUSION: Accurate assessment of the position of a jugular oxygen saturation catheter can be made by use of specific bony landmarks seen on anteroposterior radiographs of the skull.

Brain Edema↗
PubMed1995

Technetium-99m-galactosyl-neoglycoalbumin combined with iodine-123-Tyr-(A14)-insulin visualizes human hepatocellular carcinomas.

UNLABELLED: Human hepatocellular carcinoma (HCC) is the most frequent primary hepatic malignancy and its diagnosis by conventional methods is still difficult. We hypothesized that the expression of specific receptors could possibly be used to improve in vivo localization of HCC with specific receptor-based radioligands. METHODS: In initial in vitro studies, receptor binding of 99mTc-galactosyl-neoglycoalbumin (99mTc-NGA) and 123I-Tyr-(A14)-insulin to HCC was investigated. Scintigraphy was performed in 45 patients with histologically confirmed HCC using either 99mTc-NGA (75-150 MBq; 25-50 nmole, n = 27) and/or 123I-Tyr-(A14)-insulin (100-150 MBq; 7.5-10 micrograms, n = 30). RESULTS: HCC (1256 +/- 290 pmole bound/mg protein, Kd = 3.4 +/- 2.9 nM) expressed a 1000-fold higher number of specific receptors for 123I-Tyr-(A14)-insulin compared to normal liver tissue (2.4 +/- 0.8 pmole bound/mg protein, Kd = 4.2 +/- 2.4 nM), whereas HCC did not express receptors specific for 99mTc-NGA. All HCC lesions were identified as cold spots after injection of 99mTc-NGA, whereas 123I-Tyr-(A14)-insulin accumulated in these lesions, indicating HCC-to-normal liver ratios of 1.6 +/- 0.4 in the mean. Subtraction images obtained from planar studies visualized 123I-Tyr-(A14)-insulin in HCC lesions detected by 99mTc-NGA as cold spots. CONCLUSION: This hepatocyte receptor-specific, double-tracer method using 99mTc-NGA and 123I-Tyr-(A14)-insulin could become clinically useful in the diagnosis of HCC.

Aged↗
PubMed1994

Holmium: YAG laser surgery in obliterated cochleas: an experimental study in human cadaver temporal bones.

A pulsed holmium:YAG laser (lambda = 2120 nm) was used to reopen the basal turn of artificially obliterated human cochleas in freshly dissected cadavers. This allowed intracochlear insertion of the stimulation electrode of a cochlear implant under simulated surgical conditions. Laser energy was transmitted through a 400-microns nylon fiber via the opened facial recess directly to the round window niche. At an energy level of 500 mJ per 2.5 microseconds pulse, a repetition rate of 2 Hz, and an exposure time of 20-30 s, the photo-ablative mechanism of laser-bone interaction led to a 8-10 mm recanalization of the basal turn of the cochlea without damaging surrounding structures. The artificial bony occlusion and the recanalized basal turn of the cochlea were visualized by means of computed tomography and studied under light microscopy, using a histologic thin-section technique.

Aluminum Silicates↗
PubMed1994

[Color Doppler ultrasound of kidney transplants. Does the resistance index facilitate diagnosis of chronic kidney failure?].

The retrospective study under report assessed the diagnostic capability of colour Doppler sonography (CDS) with measurement of the resistive index (RI) in the long-term follow-up of patients with renal allografts. 210 CDS examinations were performed in 115 patients. The time since transplantation ranged from 6 months to 22 years. The RI was correlated to laboratory parameters of renal allograft function (serum creatinine, urinary protein levels and serum-cyclosporine). In 97 of 210 examinations, serum creatinine was elevated (> 1.5 mg% or an increase of more then 0.3 mg% within the last 6 months). In 35 out of these examinations RI was > 70%, in 62 RI was < or = 70%. Thus, with a threshold RI of 70%, sensitivity of the RI in the diagnosis of renal allograft dysfunction is 36% and specificity 62%, respectively. There was no significant difference in the RI between examinations of allografts with normal function (68.2% +/- 7.5%) and those with dysfunction (68.5% +/- 8.5%). Furthermore, there was no significant correlation between the RI and any of the laboratory parameters. CDS with calculation of the RI cannot differentiate in the long-term follow-up between allografts with normal function and those with dysfunction.

Adolescent↗
PubMed1994

[Experimental laser surgery of the ossified cochlea].

A pulsed holmium: YAG-laser (lambda = 2120 nm) was used to reopen the basal turn of artificially obliterated human cochleas in freshly dissected cadavers for intracochlear insertion of the stimulation electrode of a cochlear implant under simulated surgical conditions. Laser energy was transmitted through a 400 microns nylon fibre via the opened facial recess directly to the round window niche. At an energy level of 500 mJ/2.5 microseconds pulse, a repetition rate of 2 Hz, and an exposure time of 20-30 s, the photo-ablative mechanism of laser-bone interaction, which has only a limited thermal component, led to recanalisation of the basal turn of the cochlea in a length of 8-10 mm without damaging the surrounding structures. Light microscopic changes in the cochlea were evaluated following laser recanalisation. The artificial bony occlusion and the recanalised basal turn of the cochlea were visualised by means of computed tomography and histological thin section technique.

Cochlea↗