PubMed Health⌕ Search

Biomedical subjects

F Dammann

Publications and source records attributed to F Dammann.

At least 37 records · Page 2Linked to original sources
PubMed2001

Spindle cell lipoma of the parapharyngeal space: first report of a case.

Spindle cell lipomas are usually located in the subcutaneous tissue of the back, shoulders, and neck. To our knowledge, the presence of such a tumor in the parapharyngeal space has not yet been described. We evaluated a 45-year-old man with a tender swelling of the right parotid area that had reached the submandibular area. Clinical examination and magnetic resonance imaging revealed the presence of a tumor that coated the parotid area laterally and extended into the center of the parapharyngeal space, thus causing a dislocation of the pharyngeal muscles and mucosa. We performed a total parotidectomy and submandibulectomy on the right side and extirpated the parapharyngeal tumor. We were able to spare the facial nerve, and no facial paralysis occurred. Histologic examination revealed an atypical lipomatous tumor with a remarkably large portion of spindles.

Biopsy, Needle↗
PubMed2000

[Hybrid 3D visualization and virtual endoscopy in cochlear implants].

PURPOSE: The aim of this study was to demonstrate on a complex anatomical structure the possibilities and the advantages of a superimposition of a color-coded surface and volume rendering (hybrid rendering) method with the possibility of the performance of a virtual endoscopy. MATERIAL AND METHOD: In 6 patients with cochlear implants a high-resolution spiral computed tomography of the petrous bone was performed. The cochlear implants, the middle and inner ear structures were visualized using a color-coded surface rendering method, either shaded or as a grid. The petrous bone was visualized using a transparent volume rendering method. RESULTS: The hybrid 3D visualization uses the advantages of both the color-coded 3D surface and volume rendering method. In comparison to the axial source images, the hybrid 3D visualization thus facilitates a clearer representation and better assessment of the complex topographical relationship without loss of diagnostic information. The virtual endoscopy facilitates an intraluminal visualization and inspection of all color-coded 3D surface- and volume rendered structures. CONCLUSIONS: The hybrid rendering and virtual endoscopy make the morphological assessment of cochlear implants easier by the simultaneous visualization of the surrounding structures and thereby support the diagnostic imaging methods. This image processing method can be used pre-operatively for the individual planning, simulation, training and further development of surgical procedures and interventions and post-operatively for the control of the position and further developments of implants.

Adolescent↗
PubMed2000

[Radiation exposure during spiral-CT of the paranasal sinuses].

PURPOSE: Determination of the radiation doses in spiral CT of the paranasal sinuses using a variety of mAs values and scan protocols. MATERIAL AND METHODS: CT examinations of the paranasal sinuses were performed using an Alderson-Rando phantom. Radiation dose was determined by LiF-TLD at the level of high risk organs in the head and neck region for combinations of different scan parameters (2/3, 3/3, 3/4 mm) and decreasing charges (200, 150, 100, 50, 25 mAs) on a spiral CT. Additional measurements were performed on three other CT scanners using the 2/3 mm protocol at 50 mAs, and a single slice technique (5/5 mm) on one scanner. RESULTS: The lowest dose values found were 1.88 mGy for the eye lenses, 1.35 mGy for the parotid gland, 0.03 mGy for the thyroid gland and 0.1 mGy for the medulla oblongata using 2 mm collimation and 3 mm table feed at 25 mAs. Maximal dose values resulted using the 3/3 mm protocol at 200 mAs (31.00 mGy for the eye lense, 0.65 mGy for the thyroid gland). There were no significant differences found between the different CT scanners. CONCLUSIONS: Using up-to-date CT scanners, radiation exposure may be reduced by a factor of 15-20 compared to that of conventional CT technique. Thus, the exposure of the eye lens comes to only a thousandth of the value supposedly inducing a cataract, as published by the ICRP.

Humans↗
PubMed2000

[Multislice spiral CT of the paranasal sinuses: first experiences using various parameters of radiation dosage].

PURPOSE: To evaluate the potential of multislice CT in the diagnosis of the paranasal sinuses. METHODS: Dose measurements were performed exposing an Alderson Rando phantom in a four-slice spiral CT (MS-CT) while applying a variety of scan parameters. Additionally, 30 consecutive patients underwent a transversal examination by the MS-CT using 1/1/3.5/0.5 mm spiral parameters and an additional transversal or coronal scan on a conventional single slice spiral CT (SS-CT) with 2/3/1 mm. Coronal reformations of the MS-CT were compared with the primary coronal SS-CT, or coronal reformations of the transversal SS-CT, respectively, with regard to image quality and depiction of relevant anatomical details of the region. RESULTS: Superficial exposure values at the level of the eye lenses as well as for the thyroid gland were superior for MS-CT (3.62 mGy, and 0.12 mGy, resp.) as compared to SS-CT (2.96 mGy, and 0.07 mGy). Image quality was equal or superior for MS-CT as compared to SS-CT in all but one case. Drawbacks of SS-CT, such as dental amalgam artifacts, stair step artifacts or partial volume artifacts did not notably affect the coronal reformations of MS-CT. CONCLUSION: MS-CT seems to have the potential to replace primary coronal CT of the paranasal sinuses without any loss of image quality, but may even improve the overall diagnostic value. Radiation doses may still have to be reduced.

Humans↗
PubMed2000

[Locally recurring extramedullary plasmacytoma of the upper aerodigestive tract].

BACKGROUND: Extramedullary plasmacytomas (EMP) are plasma cell tumors in which by definition the primary tumor is extramedullary. Most of them are found in the upper aerodigestive tract. PATIENTS: In this study we describe 3 patients with EMP. The first case is a locally recurrent EMP with recurrent involvement of cervical lymph nodes. The first manifestation of EMP was 31 years ago. Hence, this is one of the longest clinical courses of recurrent EMP ever described in the literature. Case 2 is a locally aggressive recurrent EMP. Case 3 is a localized solitary EMP that could be successfully treated by surgery alone. RESULTS AND CONCLUSIONS: Different classifications of EMP described in the literature are discussed. If these classifications are applied to our cases neither the tumor stage nor the histological picture allow definite conclusions about the prognoses to be drawn. Metastases in regional lymph nodes do not necessarily mean a worse prognosis. Overall, compared to MM with a ten year survival rate of 18% the prognosis is more favorable in EMP with a ten year survival rate of 50%. After a generalized plasma cell neoplasia has been excluded EMP in the head and neck should be treated like a locally aggressive and potentially metastatic tumor. From our experiences we recommend a primary surgical therapy followed by radiation therapy if necessary.

Aged↗
PubMed2000

[High resolution multislice CT of the lung: comparison with sequential HRCT slices].

PURPOSE: To compare the image quality of high-resolution (HR) spiral CT scans from a multislice CT scanner with sequential HRCT scans from a singleslice CT scanner. MATERIALS AND METHODS: 20 patients with diffuse lung disease received a high-resolution spiral CT on a multislice scanner (4 slices) and 5 HRCT single slices (1 mm) on a singleslice scanner. Scan parameters of the multislice scanner were: Collimation 4 x 1 mm, pitch 6, slice thickness 1 mm. 5 HRCT slices were compared to the corresponding HR spiral CT slices using a 5-point scale by 5 radiologists with regard to the image quality and the number of artifacts. The evaluation was performed with a multivariate analysis (MANOVA test). RESULTS: Overall impression of image quality, noise, central vessels and bronchi, and all pathological changes were not significantly different between the two CT methods. Sequential HRCT scans were considered to be significantly better than HR spiral CT scans for spatial resolution (p = 0.02), depiction of peripheral vessels (p = 0.02), and of small bronchi (p = 0.05), and significantly worse for depiction of interlobar septa (p < 0.001). Diagnostically relevant differences were found in only 2.2%. Breathing and heartbeat artifacts each were 3 times higher in the sequential HRCT technique than in the multislice-spiral technique (p < 0.0001). CONCLUSION: HR spiral CT scans performed on a multislice CT scanner provide significantly less artifacts and an equal diagnostic image quality compared to sequential HRCT scans performed on a singleslice CT scanner. Multislice spiral CT in HR technique may replace the common scanning technique with conventional spiral CT and additional HRCT scans for diffuse lung diseases.

Adult↗
PubMed1999

Inverted papilloma of the nasal cavity and the paranasal sinuses: using CT for primary diagnosis and follow-up.

OBJECTIVE: Morphologic criteria for the diagnosis of primary and recurrent inverted papilloma as revealed on CT were evaluated in a large series. MATERIALS AND METHODS: Findings of 121 CT examinations that had been performed in 32 patients with histologically proven inverted papilloma were retrospectively analyzed using the following morphologic criteria: localization, size, surface configuration, and bony changes. RESULTS: Unilateral tumor localization involving the lateral nasal wall and the middle meatus was the feature that best correlated with the finding of primary inverted papilloma. A lobulated surface pattern was another typical sign, which was revealed on 19 of the 29 CT scans of patients with primary inverted papilloma. Although tumor localization and the finding of a newly grown soft-tissue mass were less reliable criteria to differentiate between recurrent inverted papilloma and postoperative complications or concomitant inflammatory disease, a lobulated surface pattern was seen on 26 of the 28 CT scans of patients with tumor recurrence but on only three of the 64 follow-up CT scans of patients without recurrent inverted papilloma. CONCLUSION: A unilateral mass within the nasal cavity or paranasal sinuses with a surface configuration that appears lobulated on CT is, to our knowledge, a new sign that strongly suggests inverted papilloma as a primary diagnosis and also suggests inverted papilloma in patients with tumor recurrence.

Adult↗
PubMed1998

[Value of Schüller conventional roentgen diagnosis and computerized tomography of the temporal bone in preoperative diagnosis of the Tübingen implantable cochlear amplifier].

Recently, the transducer and microphone of a cochlea amplifier implant (CAI) for the treatment of sensorineural cochlear hearing loss have been developed further for implantation into the mastoid cavity. At present, the University of Tuebingen implantable cochlea amplifier consists of an implantable microphone and an implantable piezoelectric transducer. It has been implanted into the first patients. Successful future application of this new implant depends on the suitable fit of the CAI within a patient's mastoid cavity. Using conventional X-ray and CT scans, we analyzed 50 cadaver specimens of the temporal bone before total mastoidectomy. After total mastoidectomy, the volume of the mastoid cavity was measured using CT scans and water volume determination. Finally, the CAI was implanted into those temporal bones that were large enough to house it. Our results demonstrate that the degree of pneumatization in the conventional Schüller X-ray is already a good parameter for preoperative evaluation.

Cochlear Implantation↗
PubMed1998

High-resolution cardiac imaging using an interleaved 3D double slab technique.

A three-dimensional (3D) gradient-echo sequence with interleaved double-slab excitation was developed and optimized for the requirements in pediatric cardiac imaging. For this purpose high contrast between blood and myocardium signal should be obtained without the use of contrast agents. An acceptable measuring time for a large region examined with high spatial resolution should be achieved as well, especially with regard to the small structures of the heart and vessels of infants. The presented approach works with gradient moment nulling and a short echo time of 5.5 ms resulting in generally high signal intensity and only minor signal losses due to turbulent flow. The sequence allows simultaneous ECG-gated recording of two separately excited slabs with small thickness (10 mm) and with a distance of several centimeters between them. Thus, common effects of presaturation in 3D imaging can be avoided, although a relatively short measuring time is achievable. In order to get a 3D data set with good signal homogeneity of blood and of the other structures across a large volume of interest several double-slab measurements with suitable positions must be performed. The latter aspect is especially important for postprocessing techniques as multiple planar reconstruction and maximum intensity projection. Examples of applications of the new technique and appropriately postprocessed images are presented allowing demonstration even of subtle cardiac malformations.

Artifacts↗
PubMed1998

[Intra-arterial calcium stimulation for preoperative localization of insuloma].

PURPOSE: Objective is to evaluate the efficacy of the intraarterial calcium test in the preoperative localisation of insulinomas. MATERIAL AND METHOD: To stimulate the pathological release of insulin, calcium gluconate (0.015 meq Ca++/kg) was selectively injected into the arteries supplying the pancreas. Prior to calcium injection and 30, 60, 90 and 120 seconds later, 5 ml samples of blood were obtained from the right or from both right and left hepatic veins. Insulin levels were then determined by mean of immunoassays. A twofold increase in insulin level in the venous sample after 30 or 60 seconds localised the insulinoma to the region of the pancreas supplied by the selectively injected artery. Results of the calcium test were prospectively analysed in 6 patients and compared with operative findings. RESULTS: All 6 patients had a surgically proved solitary and benign insulinoma. Calcium stimulation with venous sampling provided true-positive localisation of insulinomas in all patients without suspicion of liver metastasis. All 6 patients currently have normal insulin levels after a mean period of 16 months (range 4-24 months) with no evidence of hypoglycaemia on fasting. CONCLUSION: Intraarterial stimulation with calcium and hepatic vein samplings for insulin gradients is a very sensitive minimally invasive functional method and may replace transhepatic portal venous samplings for the preoperative detection of insulinomas.

Adult↗
PubMed1998

Insulinoma and islet cell hyperplasia: value of the calcium intraarterial stimulation test when findings of other preoperative studies are negative.

PURPOSE: To evaluate the efficacy of the intraarterial calcium test in localizing sources of hyperinsulinism that remain undetectable at preoperative morphologic studies. MATERIALS AND METHODS: Twenty-four patients with clinically proved endogenous hyperinsulinism due to tumorous insulin production were prospectively enrolled. They underwent ultrasound (US), computed tomography, magnetic resonance imaging, endoscopic US, abdominal arteriography, and a calcium test, in which insulin concentrations were measured in hepatic venous blood after selective intraarterial calcium stimulation. The results of the calcium test in seven patients (five women, two men; age range, 30-66 years; mean age, 47 years) with negative findings of morphologic studies are described. RESULTS: Six solitary insulinomas (mean diameter, 0.73 cm) and one nodular hyperplasia were diagnosed after surgery. In all seven cases, calcium test findings allowed accurate localization of the pathologic source of insulin secretion. In three of these seven cases, results of arterial calcium stimulation with hepatic venous sampling (ASVS) affected intraoperative management. An increase in insulin concentration after stimulation in the hepatic artery was not observed, making hepatic metastases unlikely. CONCLUSION: ASVS, which is procedurally simpler than transhepatic pancreatic venous sampling, is effective for localizing sources of hyperinsulinism not detected with preoperative morphologic studies.

Calcium Gluconate↗
PubMed1997

Perianal complications of Crohn disease: MR imaging findings.

The aim of this study was to revisit anal anatomy, to explain surgical terminology in perianal complications of Crohn disease, and to show the MR imaging findings of perianal fistulas and abscesses. To this end more than 200 patients were studied using surface coils (Helmholtz; phased array) at 1.0 and 1.5 T. Transverse and coronal T1- and T2-weighted images were obtained. Parks' classification was used to describe perianal abscesses and fistulas. This pictorial essay shows the normal anal anatomy and pathologic findings such as subcutaneous, para-anal, ischiorectal, intersphincteric, and supralevatoric abscesses and fistulas. MR imaging with surface coils is well suited to showing the anal anatomy and to reliably describing perianal abscesses and fistulas according to surgical terminology.

Abscess↗
PubMed1997

[In vitro study of morphology of the bladder wall using MR tomography at 1.0 Tesla: correlation with histology].

PURPOSE: Evaluation of the potential of various MR techniques to differentiate bladder wall layers verified by histological findings. MATERIAL AND METHOD: 6 bladder specimens of pigs were examined in vitro using T1-weighted spin-echo-sequences, T2-weighted Turbo-SE, fat suppressed T2-weighted SE, and inversion recovery sequences. The MR images were obtained before and after fixating the specimens in formalin. Measurements of the thickness of bladder wall layers were performed on both sets of MR images as well as on histological sections, RESULTS: T2-weighted SE images showed three layers of different signal intensities: one innermost band of very high signal, one inner band of low and one outer band of intermediate signal corresponding histologically tunica propria and two different muscle layers. Inversion recovery technique provided similar findings but were able to avoid chemical-shift artifacts. After 24 hours in formalin, the signal intensity relation of the two muscle layers was inverted. The thickness of total bladder wall was not reduced significantly. Concerning the thickness of urinary bladder wall, histological measurements and evaluation of MR images correlated well. CONCLUSION: MR imaging enables the differentiation of three bladder wall layers. Inversion recovery technique achieved the best image quality by avoiding chemical shift artifact.

Animals↗