[Simplified production of multimedia based radiological learning objects using the flash format]. / Vereinfachte Herstellung multimedialer radiologischer Lernobjekte mit dem Flash-Format.

PURPOSE: Evaluation of the applicability of the Flash Format for the production of radiological learning objects used in an e-learning environment. MATERIAL AND METHODS: Five exemplary learning objects with different didactic purposes referring to radiological diagnostics are presented. They have been intended for the use within the multimedia, internet-based e-learning environment LaMedica. Interactive learning objects were composed using the Flash 5.0 software (Macromedia, San Francisco, USA) on the basis of digital CT and MR images, digitized conventional radiographs and different graphical elements prepared as TIFF files or in a vector graphics format. RESULTS: After a short phase of initial skill adaptation training, a radiologist author was soon able to create independently all learning objects. The import of different types of images and graphical elements was carried out without complications. Despite manifold design options, handling of the program is easy due to clear arrangement and structure, thus enabling the creation of simple as well as complex learning objects that provided a high degree of attractiveness and interaction. Data volume and bandwidth demand for online use was significantly reduced by the Flash Format compression without a substantial loss of visual quality. CONCLUSION: The universally compatible Flash Format offers an opportunity for the simple production of radiological learning objects that fulfill all relevant needs of modern internet based e-learning environments, such as interactivity, employment of multimedia and convertibility.

Comparison of magnetic resonance imaging methods for examinations of abdominal aortic aneurysms.

RATIONALE AND OBJECTIVES: Different magnetic resonance imaging techniques were compared with respect to available anatomic information regarding abdominal aortic aneurysms (AAA) and regions involved in thrombosis. METHODS: Twenty patients with AAA were examined by turbo spin-echo (TSE) imaging of coronal and transverse slices, resulting in black blood images. Bright blood imaging was performed using a spoiled gradient-echo sequence with gradient moment nulling. Sets of 25 to 50 thin slices were recorded sequentially in a single slice mode using coronal and transverse orientation. Both sets of bright blood images were reconstructed by maximum intensity projection. RESULTS: In all patients, the size and shape of the AAA could better be assessed by the TSE images than by the gradient-echo images. In contrast, reliable differentiation of thrombotic areas and of the perfused lumen was possible in only 56% of the slices recorded by TSE imaging but in 94% of the gradient-echo images. The two-dimensional inflow technique provided clearly higher sensitivity even to slow blood flow than TSE imaging. Maximum intensity projection reconstructions from sets of coronal two-dimensional inflow images often did not depict the lower part of the AAA because of saturation effects, whereas sets of transverse slices provided complete angiograms of the aortoiliac vascular tree. DISCUSSION: At this time, no single magnetic resonance method can provide all essential information. A comprehensive examination should include TSE imaging for topographic assessment and transverse two-dimensional inflow imaging for analysis of thrombotic areas.

M2 muscarinic receptors on the iris sphincter muscle differ from those on iris noradrenergic nerves.

The pre- and postjunctional affinity constants of a series of muscarinic antagonists were determined in guinea pig and rabbit irises. Field stimulation-evoked [3H]noradrenaline release from superfused isolated irises was concentration dependently inhibited by (+/-)-methacholine, confirming the presence on the iris noradrenergic nerves of prejunctional inhibitory muscarinic receptors. The affinity constants of the antagonists at the pre- and postjunctional receptors are compatible with the coexistence in the iris of two different M2 receptors: the cardiac (M2 alpha) subtype on the noradrenergic nerves and the smooth muscle (M2 beta) subtype on the iris sphincter muscle. The rank order of potency of the antagonists studied at the prejunctional site was: atropine greater than himbacine greater than AF-DX 116 greater than pirenzepine greater than hexahydrosiladifenidol. The order of potency at the postjunctional receptors mediating the methacholine-induced isotonic contraction of the isolated rabbit iris sphincter was: atropine greater than hexahydrosiladifenidol greater than pirenzepine greater than himbacine greater than AF-DX 116.

AF-DX 116 differentiates between prejunctional muscarine receptors located on noradrenergic and cholinergic nerves.

Prejunctional affinity constants of the cardioselective muscarine receptor antagonist AF-DX 116 (11-[(2-[(diethyl-amino)methyl]-1-piperidinyl)acetyl]-5,11-dihydro-6 H-pyrido [2,3-b] [1,4] benzodiazepine-6-one) were determined for muscarine autoreceptors on cholinergic nerves of the guinea-pig ileum and for heteroreceptors on noradrenergic nerves of the rat heart and guinea-pig iris. AF-DX 116 antagonized with low affinity the muscarinic inhibition induced by arecaidine propargyl ester of the stimulation-evoked [3H]acetylcholine overflow (pA2 6.74) from the guinea-pig ileum. In contrast, AF-DX 116 was more potent in antagonizing the methacholine-induced inhibition of the stimulation-evoked [3H]noradrenaline overflow from rat heart (pA2 7.29) or guinea-pig iris (pA2 7.57). The data confirm previously reported differences between prejunctional muscarine heteroreceptors in the rat heart which belong to the cardiac subtype (M2 alpha or M2) and autoreceptors in the guinea-pig ileum that cannot be distinguished from the ileal subtype (M2 beta) or M3).

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.

[Image processing in radiology]. / Bildverarbeitung in der Radiologie.

Medical imaging processing and analysis methods have significantly improved during recent years and are now being increasingly used in clinical applications. Preprocessing algorithms are used to influence image contrast and noise. Three-dimensional visualization techniques including volume rendering and virtual endoscopy are increasingly available to evaluate sectional imaging data sets. Registration techniques have been developed to merge different examination modalities. Structures of interest can be extracted from the image data sets by various segmentation methods. Segmented structures are used for automated quantification analysis as well as for three-dimensional therapy planning, simulation and intervention guidance, including medical modelling, virtual reality environments, surgical robots and navigation systems. These newly developed methods require specialized skills for the production and postprocessing of radiological imaging data as well as new definitions of the roles of the traditional specialties. The aim of this article is to give an overview of the state-of-the-art of medical imaging processing methods, practical implications for the radiologist's daily work and future aspects.

[In vitro study of morphology of the bladder wall using MR tomography at 1.0 Tesla: correlation with histology]. / In-vitro-Untersuchung der Morphologie der Harnblasenwand in der MR-Tomographie bei 1,0 Tesla: Korrelation mit der Histologie.

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.

[Evaluation of different 16-row CT colonography protocols using a porcine model]. / Evaluation unterschiedlicher 16-Zeilen-CT-Colonographie-Protokolle am Schweinedarmmodell.

PURPOSE: To develop and to test an easily produced biological colon model with simulated polypoid lesions. Application of this phantom for the selection of an optimized scan protocol of 16-row CT colonography (CTC) for clinical use. METHODS AND MATERIAL: Six polypoid lesions (1 - 6 mm) were simulated with sutures on the inner face of a porcine colon segment (20 cm). After distending the colon segment with air, the phantom was placed in a water quench and CT scans were performed on a MDCT-scanner (Somatom Sensation 16, Siemens, Forchheim). At constant values for collimation (16x0.75 mm) and voltage (120 kV), 54 different combinations of mAs values (50, 75 and 100 mAs), pitch factors (1, 1.25 and 1.5) and slice thicknesses (0.75, 1.0, 1.5, 2.0, 3.0 and 5.0 mm) were tested systematically. The phantom was scanned in the longitudinal and transverse axis to simulate the different orientation of the colon in the abdomen. Axial slice images and virtual endoscopic views of all data sets were presented separately to 2 radiologists who independently determined number and size of detectable polyps. Dose exposure was measured with an Alderson phantom. RESULTS: The colon model offered a realistic imitation of a polyp-covered, human colon. The experimental set-up allowed a systematic evaluation of polyp detection related to lesion size, orientation of the colon and CTC parameters, with other influencing factors mostly excluded. Polyps were significantly better detected in the longitudinal than in the transverse orientation of the colon. For the detection of lesions of at least 3 mm, a low dose (50 mAs) 16-row CTC should be combined with a pitch of 1.5 and a maximum slice thickness of 3 mm. For the depiction of polyps smaller than 3 mm, slice thickness and pitch should amount to 1 mm and 1.0, respectively. Effective dose of this low dose protocol is 4.08 mSv. CONCLUSION: The porcine colon phantom represents a realistic and easily produced alternative to other colonography models. It allows a preselection of a CTC-protocol for subsequent clinical testings. If the high in vitro performance of the low-dose 16-row CTC-protocol is confirmed on a human collective, the use of 16-row technique would represent a big step for CTC toward a screening method.

[Multislice spiral CT of the paranasal sinuses: first experiences using various parameters of radiation dosage]. / Mehrschicht-Spiral-CT der Nasennebenhöhlen: Erste Erfahrungen unter besonderer Berücksichtigung der Strahlenexposition.

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.

[Analysis of artefacts by virtual endoscopy visualization of spiral CT data]. / Analyse von Artefakten bei der virtuellen endoskopischen Darstellung auf Basis von Spiral-CT-Daten.

PURPOSE: Analysis of patterns and causes of artifacts found in endographic visualization of spiral CT data. MATERIALS AND METHODS: A straight perspex tube with a diameter of 20 mm was scanned in three different positions with ten scan protocols of varying table feed, increment, kernel, and signal to noise ratio (Tomoscan AVE, Philips). The resulting 30 CT datasets were visualized as a virtual endoscopy (VE) with ten different visualization protocols (Easy Vision 4.2, Philips) of varying threshold, resolution, and perspective angle. 300 VE datasets were analyzed by two radiologists and compared with the visualization of a software-generated tube in order to differentiate scanning and software artifacts. RESULTS: Five different classes of artifacts have been identified. Two of them result from the scanning process and two from the specific visualization method. Spiral patterns and the unevenness of the tube wall vary with the scanning parameter. Moiré-like patterns are caused by the VE software and depend on the visualization matrix. A high perspective angle distorts the size and form of the tube and makes it difficult for the observer to locate his position within the tube. The appearance of pseudoforamina depends on both the scanning and the visualization parameters. CONCLUSION: The knowledge of the patterns and potential causes of artifacts in endographic visualization of spiral CT scans are the basis for interpretation and optimization of this visualization method.

[Value of dacryocystography in localization diagnosis of lacrimal duct stenosis]. / Stellenwert der Dakryozystographie in der Lokalisationsdiagnostik der Tränenwegstenosen.

PURPOSE: Evaluation of dacryocystography in the preoperative localisation of stenosis of the lacrimal passage. METHOD: The lacrimal system of 20 patients (25 eyes) suffering from lacrimal passage obstruction was examined either by conventional (n = 20) or by digital (n = 5) technique. Diagnostic imaging was evaluated concerning topographic Information of the pathologic lacrimal system, localisation of the level and differential diagnosis of the cause of the obstruction. RESULTS: Cause of the obstruction was chronic dacryocystitis (n = 16), dacryolithiasis (n = 1), atresia of the lacrimal duct (n = 2), posttraumatic lesions (n = 3), rhinosinusitis (n = 1) and carcinoma of the maxillary sinus (n = 1). In 23 of 25 cases (92%) we found an exact correlation between dacryocystography and the intraoperative findings. The variation of stenosis types as well as different examination techniques are presented and compared with literature findings. CONCLUSION: Dacryocystography is a valuable method in the diagnosis and preoperative planing in lacrimal system obstruction.

[Value of the AMBER system in interstitial lung changes]. / Wertigkeit des AMBER-Systems bei interstitiellen Lungenveränderungen.

PURPOSE: To evaluate the diagnostic value of the AMBER technique in the diagnosis of interstitial lung disease. METHODS: A prospective comparison of conventional and AMBER chest radiographs of 52 patients was performed using HR-CT as a gold standard on the same day. ROC analysis based on the results of 5 observers was carried out to quantify the diagnostic value of both chest radiograph techniques. RESULTS: The ROC area for the AMBER system (0.860) showed statistically significant superiority in comparison to the conventional technique (0.828). This was mainly due to the better sensitivity of the AMBER system (65.3%) compared to the conventional chest radiographs (39.8%) within the lung regions superimposed by the diaphragm or the mediastinum. No difference between both methods was observed within the lung regions without superimposion. CONCLUSION: AMBER technique improved conventional chest radiography in the diagnosis of interstitial lung disease due to superiority in the superimposed lung regions.

[Clinical implication of parameter-optimized 3D-FISP MR angiography (MRA) in children with aortic coarctation: comparison with catheter angiography]. / Stellenwert einer parameteroptimierten 3D-FISP-MR-Angiographie bei Kindern mit Aortenisthmusstenose im Vergleich zur Katheterangiographie.

PURPOSE: To implement parameter-optimized 3D-FISP MR angiography (MRA) with interleaved double-slab excitation and to compare the result with catheter angiography in children with aortic coarctation. MATERIALS AND METHODS: Eighteen children aged 2 - 15 years (mean 9.1 years) underwent MR imaging on a 1.5T body scanner (Magnetom Vision, Siemens, Germany). All patients had undergone correlative catheter angiography. T1-weighted turbo spin echo (TSE) images (TR 600 ms, TE 17 ms, flip 160 degrees, slice thickness 2 - 4 mm) were obtained in axial and parasagittal orientation, followed by an optimized 3D-FISP MR angiography in a sagittal plane (TR 12.5 ms, TE 5.5 ms, flip 22 degrees, matrix 256 x 256, slice thickness 1.25 mm). All children were sedated but on spontaneous breathing. Image quality was graded by two experienced reviewers using a 4-point scoring system. Source images and reformatted maximum intensity projections (MIP) were analyzed for blood-tissue contrast as well as size and focal stenoses of the aortic arch. RESULTS: Aortic coarctation was found in 13 of 18 patients, using the 3D-FISP MRA. A high correlation value (r = 0.96) was found compared to catheter angiography. Image quality was high in 94 % with well defined blood-tissue contrast in all cases. The sensitivity to flow and breathing motion was low. Examination time was about 15 minutes depending on volume of interest and heart rate. Diagnostic accuracy has shown improvement using a combined analysis of source and MIP images. The mentioned technique has provided an excellent display of thoracic vasculature. CONCLUSION: MR imaging represents an excellent tool for non-invasive examination of the cardiovascular system of children. The 3D-MRA allows the recording of a large 3D data set without the use of contrast agent and within an adequate measurement period, particularly in small infants unable to hold their breath. In addition, hemodynamic significance of aortic coarctation, the existence of collateral vessels and other congenital heart diseases can be described reliably by using this technique.

[High resolution multislice CT of the lung: comparison with sequential HRCT slices]. / Hochauflösende Mehrschicht-CT der Lunge: Vergleich mit HRCT-Einzelschichten.

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.

[Use of VR (virtual reality) software for preoperative implantation fitting with an implantable hearing aid as an example]. / Einsatz einer VR (Virtuelle Realität)-Software zur präoperativen Implantationsprüfung am Beispiel eines implantierbaren Hörgerätes.

PURPOSE: To prove the feasibility of a preoperative fitting test for an implantable hearing aid using a VR environment. METHODS: A high-resolution spiral CT was performed after mastoidectomy in 10 temporal bone specimens. The bony structures were segmented and merged with the Computer-Aided Design (CAD) data of the hearing aid in a VR environment. For each specimen a three-dimensional fitting test was carried out by three examiners determining the implantability of the hearing aid. The implantation simulation was compared with the real implantation procedure performed by an experienced ENT surgeon. RESULTS: The used VR system enabled real-time 3D-visualisation and manipulation of CT- and CAD-data. All objects could be independently moved in all three dimensions. The VR fitting test corresponded closely with the real implantation. The implantability of the hearing aid was properly predicted by all three examiners. CONCLUSION: Merging CT and CAD data in a virtual reality environment bears high potential for the pre-surgical determination of the fit and mountability of medical implants in complex anatomical regions.

[Hybrid 3D visualization and virtual endoscopy in cochlear implants]. / Hybride 3D-Visualisierung und virtuelle Endoskopie von Cochlea-Implantaten.

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.

[Radiation exposure during spiral-CT of the paranasal sinuses]. / Strahlenexposition bei der Spiral-CT der Nasennebenhöhlen.

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.

[Intra-arterial calcium stimulation for preoperative localization of insuloma]. / Intraarterieller Kalzium-Stimulationstest zur präoperativen Lokalisationsdiagnostik des Insulinoms.

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.

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.

The use of hybrid stereolithographic models for the planning of complex craniofacial procedures.

Preoperative planning of orthognathic surgery is usually based on plaster cast models. Those are integrated in an articulator, simulating the movement of the jaws. We present a new procedure to combine the individual jaw anatomy by stereolithographical models with dental plaster casts, which are more accurately reproducing dental and bony anatomy. For image fusion the patient and the individual plaster casts are scanned by computed tomography, the occlusal planes being covered by a splint with radioopaque makers. After threshold segmentation of both, the plaster cast and the patients skull images are fused. The plaster cast volume is then subtracted from the patients upper and lower jaw, thus sparing out the place for later fusion of stereolithographic model and plaster cast.