Switching off for future-Cost estimate and a simple approach to improving the ecological footprint of radiological departments.

PURPOSE: Besides diagnostic imaging devices, in particular computed tomography (CT) and magnetic resonance imaging (MRI), numerous reading workstations contribute to the high energy consumption of radiological departments. It was investigated whether switching off workstations after core working hours can relevantly lower energy consumption considering both ecological and economical aspects. METHODS: Besides calculating different theoretical energy consumption scenarios, we measured power consumption of 3 workstations in our department over a 6-month period under routine working conditions and another 6-month period during which users were asked to switch off workstations after work. Staff costs arising from restarting workstations manually were calculated. RESULTS: Our approach to switching off workstations after core working hours reduced energy consumption by about 5.6 %, corresponding to an extrapolated saving of 3.2 tons in carbon dioxide (CO2) emissions and 2100.70 USD/year in electricity costs for 227 workstations. Theoretical calculations indicate that consistent automatic shutdown after core working hours could result in a potential total reduction of energy consumption of 38.6 %, equaling 22.2 tons of CO2 and 14,388.28 USD/year. However, staff costs resulting from waiting times after manually restarting workstations would amount to 36,280.02 USD/year. CONCLUSIONS: Switching off workstations after core working hours can considerably reduce energy consumption and costs, but varies with user adherence. Staff costs caused by waiting time after manually starting up workstations outweigh energy savings by far. Therefore, an energy-saving plan with automated shutdown/restart besides enabling an energy-saving mode would be the most effective way of saving both energy and costs.

Inter- and Intrareader Agreement of NI-RADS in the Interpretation of Surveillance Contrast-Enhanced CT after Treatment of Oral Cavity and Oropharyngeal Squamous Cell Carcinoma.

BACKGROUND AND PURPOSE: The Neck Imaging Reporting and Data System was introduced to assess the probability of recurrence in surveillance imaging after treatment of head and neck cancer. This study investigated inter- and intrareader agreement in interpreting contrast-enhanced CT after treatment of oral cavity and oropharyngeal squamous cell carcinoma. MATERIALS AND METHODS: This retrospective study analyzed CT datasets of 101 patients. Four radiologists provided the Neck Imaging Reporting and Data System reports for the primary site and neck (cervical lymph nodes). The Kendall's coefficient of concordance (W), Fleiss κ (κF), the Kendall's rank correlation coefficient (τB), and weighted κ statistics (κw) were calculated to assess inter- and intrareader agreement. RESULTS: Overall, interreader agreement was strong or moderate for both the primary site (W = 0.74, κF = 0.48) and the neck (W = 0.80, κF = 0.50), depending on the statistics applied. Interreader agreement was higher in patients with proved recurrence at the primary site (W = 0.96 versus 0.56, κF = 0.65 versus 0.30) or in the neck (W = 0.78 versus 0.56, κF = 0.41 versus 0.29). Intrareader agreement was moderate to strong or almost perfect at the primary site (range τB = 0.67-0.82, κw = 0.85-0.96) and strong or almost perfect in the neck (range τB = 0.76-0.86, κw = 0.89-0.95). CONCLUSIONS: The Neck Imaging Reporting and Data System used for surveillance contrast-enhanced CT after treatment of oral cavity and oropharyngeal squamous cell carcinoma provides acceptable score reproducibility with limitations in patients with posttherapeutic changes but no cancer recurrence.

Compulsivity predicts fronto striatal activation in severely anorectic individuals.

Anorexia nervosa is a severe illness and shows one of the highest death rates among psychiatric or psychosomatic diseases. However, despite several lines of research, the etiology of this disease is still unknown. One of those features is the rigidity of behaviors, for example, controlling of weight and pursuing of thinness, that often meets the criteria for obsessive-compulsive behavior. In this study, it was investigated whether the clinical feature of compulsivity in anorexia nervosa patients relates to regional brain activation. Using functional magnetic resonance imaging, 12 severely anorectic women were compared to 12 normal-weight female individuals following a cue-reactivity paradigm. Cues comprised food cues of high and low calorie content as well as eating-related utensils. Voxel-based morphometric analysis indicated significantly overall reduced gray matter volume and significantly increased cerebrospinal fluids in anorexia nervosa (AN) patients, which was controlled for in subsequent analyses. Following the high-calorie stimulation, AN patients activated the right caudate body and right precuneus, whereas control subjects did not show significant regional activations. In both other conditions, low-calorie foods and eating utensils, regional brain activations did not survive FDR thresholds. During the high-calorie condition, compulsivity, that is, the subscore "obsessive thoughts," predicted activation of the superior frontal gyrus [Brodmann areas (BA) 10], inferior frontal gyrus, anterior cingulate cortex (BA 32), cingulate gyrus (BA 24), caudate body, cuneus, pre- and postcentral gyrus. The subscore "compulsive acts" correlated with activation of the claustrum during the high-calorie condition and predicted a number of deactivations of frontal and temporal regions. We conclude that in severely anorectic individuals, the degree of compulsivity predicts activation and deactivation of the fronto-striatal pathway.

Image quality and radiation exposure in 320-row temporal bone computed tomography.

OBJECTIVES: The aim was to define image quality and radiation exposure in the recently introduced 320-row CT of the temporal bone (tb) in comparison to a 16-row tb CT. METHODS: A cadaveric head phantom was used for repeated tb volume CT studies (80-120 kV, 25-150 mAs), performed in a 320-row scanner (single rotation, 0.5 mm slice thickness, kernel FC 51) in comparison to 16-row helical CT using standard acquisition parameters (SAP) of 120 kV and 75 mAs (kernel FC 53). Qualitative image evaluation was performed by two radiologists using a 5-point visual analogue scale. Image noise (D(SD)) was determined by region of interest (ROI) based measurements in cadaveric as well as water phantom studies. Dosimetric measurements of the effective dose (ED) and organ dose (OD) of the lens were performed. RESULTS: Image quality of 320-row tb CT was equivalent to 16-row CT for SAP scans, resulting in image noise levels (D(SD) 16-/320-row) of 109/237 and 206/446 for air and bone respectively. D(SD) differences were predominantly (>90%) attributable to the different kernels available for tb studies in 16- and 320-row CT. Radiation exposure for 16-/320-row SAP scans amounted to 0.36/0.30 mSv (ED) and 10.0/8.4 mGy (lens dose). CONCLUSION: 320-row volume acquisition in tb CT delivers equivalent image quality to 16-row CT while decreasing radiation exposure figures by one sixth. Image noise increase in 320-row CT is negligible with respect to image quality.

Dose exposure of patients undergoing comprehensive stroke imaging by multidetector-row CT: comparison of 320-detector row and 64-detector row CT scanners.

BACKGROUND AND PURPOSE: Recently introduced 320-detector row CT enables whole brain perfusion imaging compared to a limited scanning area in 64-detector row CT. Our aim was to evaluate patient radiation exposure in comprehensive stroke imaging by using multidetector row CT consisting of standard CT of the head, CTA of cerebral and cervical vessels, and CTP. MATERIAL AND METHODS: Organ doses were measured by using LiF-TLDs located at several organ sites in an Alderson-Rando phantom. Effective doses were derived from these measurements. Stroke protocols including noncontrast head CT, CTA of cerebral and cervical vessels, and CTP were performed on 320- and 64-detector row scanners. RESULTS: Measured effective doses for the different scanning protocols ranged between 1.61 and 4.56 mSv, resulting in an effective dose for complete stroke imaging of 7.52/7.54 mSv (m/f) for 64-detector row CT and 10.56/10.6 mSv (m/f) for 320-detector row CT. The highest organ doses within the area of the primary beam were measured in the skin (92 mGy) and cerebral hemispheres (69.91 mGy). Use of an eye-protection device resulted in a 54% decrease of the lens dose measured for the combo protocol for whole-brain perfusion with the 320-detector row CT scanner. CONCLUSIONS: Phantom measurements indicate that comprehensive stroke imaging with multidetector row CT may result in effective radiation doses from 7.52 mSv (64-detector row CT) to 10.6 mSv (320-detector row CT). The technique of 320-detector row CT offers additional information on the time course of vascular enhancement and whole-brain perfusion. Physicians should weigh the potential of the new technique against the higher radiation dose that is needed. Critical doses that would cause organ damage were not reached.

[Olfactory dysfunction: correlation of olfactory bulb volume on MRI and objective olfactometry]. / Riechstörungen: Korrelation von objektiver Olfaktometrie und volumetrischer Messungen des Bulbus olfactorius in der MRT.

PURPOSE: To define the role of olfactory bulb volume measurement by magnetic resonance imaging (MRI) for detecting olfactory dysfunction in comparison with objective olfactometry. MATERIALS AND METHODS: Thirty patients with suspected olfactory dysfunction (16 women, 14 men; mean age 52 years, range 20 - 79 years) were examined by MRI and objective olfactometry between January 2006 and January 2009. Olfactory bulb volumes were measured by two neuroradiologists using 3D MR data sets. The olfactory function was categorized as normosmia, hyposmia, and anosmia on the basis of objective olfactometry. Pearson correlation coefficients were calculated for objective olfactometry and olfactory bulb volumes on MRI. ROC analysis was performed to determine whether MRI bulb volumes can serve to predict anosmia or hyposmia. RESULTS: The bulb volumes measured by MRI ranged from 0 to 135.9 mm (3). Based on olfactometry, anosmia was present in 11 patients (total bulb volume of 15.7 +/- 23.3 mm (3)), hyposmia in 9 patients (total bulb volume of 50.0 +/- 25.5 mm (3)), and normosmia in 10 patients (total bulb volume of 110.7 +/- 21.5 mm (3)). There was good correlation (r > 0.9) between objective olfactometry and olfactory bulb volume on MRI. ROC analysis yielded a cut-off value of 32 mm (3) for anosmia, which had a sensitivity of 0.91 and specificity of 0.947. The cut-off value for olfactory dysfunction was 80.7 mm (3) (sensitivity 0.95; specificity of 0.9). CONCLUSION: The olfactory bulb volume determined by MRI is a suitable parameter for diagnosing complete or partial loss of the sense of smell.

Auditory cortex stimulation by low-frequency tones-an fMRI study.

BACKGROUND AND PURPOSE: Low-frequency tones (LFT) and infrasound (IS) are looked upon as potentially hazardous to human health. We aimed at assessing LFT/IS-induced activation of the auditory cortex by using fMRI. MATERIALS AND METHODS: fMRI was used to investigate LFT/IS perception in 17 healthy volunteers. Short tone bursts of 12, 36, 48 and 500 Hz were delivered directly into the right external ear canal through a 12-m long silicone tube and an ear plug. Sound pressure levels (SPL) and spectral analysis of the stimuli and scanner noise were measured in situ by using a metal-free optical microphone and a fiber-optic cable. RESULTS: SPL-dependent activation of the superior temporal gyrus, i.e. Brodmann areas (BA) 41 and 42 as well as BA 22, was delineated subsequent to acoustic stimulation with 12-, 48- and 500-Hz stimuli. Thresholds for LFT/IS-induced brain activation were between 110 and 90 dB SPL in normal hearing subjects. Spectral analysis revealed the occurrence of harmonics together with LFT, of which 36-Hz harmonics interfered with IS exposure at 12 Hz as well as scanner noise. CONCLUSION: Our results provide evidence that auditory cortex activation may be induced by LFT/IS exposure, depending on sound pressure levels applied. Clinical implications of our findings will have to be addressed by subsequent studies involving patients presumptively suffering from LFT-dependent disorders.

320-slice CT neuroimaging: initial clinical experience and image quality evaluation.

The aim of this study was to report initial clinical experience with a 320-slice CT scanner and to perform an image quality evaluation. 26 patients with presumptive cerebrovascular pathology underwent 320-slice CT. Single-rotation CT of the head, incremental CT angiography (three-dimensional (3D) CTA) as well as four-dimensional whole-brain CTA (4D CTA) and whole-brain CT perfusion (CTP) were performed and the resulting images were assessed for quality and compared with those obtained with 64-slice CT protocols. 320-slice CT neuroimaging could be performed in all cases. The image quality of 320-slice CT of the head and 3D CTA was inferior to that of the 64-slice protocols. The image quality of 4D 320-slice CTA was rated as inferior to both 320- and 64-slice 3D CTA. 4D CTA-CTP imaging added information with pivotal clinical implications. 320-slice CT neuroimaging is feasible technique that permits whole-brain 4D imaging and has the potential to identify pathologies with altered haemodynamics. However, image quality is a limitation of this technique at present.

Linear and volume measurements of pulmonary nodules at different CT dose levels - intrascan and interscan analysis.

PURPOSE: To compare the interobserver variability of the unidimensional diameter and volume measurements of pulmonary nodules in an intrascan and interscan analysis using semi-automated segmentation software on ultra-low-dose computed tomography (ULD-CT) and standard dose CT (SD-CT) data. MATERIALS AND METHODS: In 33 patients with pulmonary nodules, two chest multi-slice CT (MSCT) datasets (1 mm slice thickness; 20 % reconstruction overlap) had been consecutively acquired with an ultra-low dose (120 kV, 5 mAs) and standard dose technique (120 kV, 75 mAs). MSCT data was retrospectively analyzed using the segmentation software OncoTREAT (MeVis, Bremen, Germany, version 1.3). The volume of 229 solid pulmonary nodules included in the analysis as well as the largest diameter according to RECIST (Response Evaluation Criteria for Solid Tumors) were measured by two radiologists. Interobserver variability was calculated and SD-CT and ULD-CT data compared in an intrascan and interscan analysis. RESULTS: The median nodule diameter (n = 229 nodules) was registered with 8.2 mm (range: 2.8 to 43.6 mm, mean: 10.8 mm). The nodule volume ranged between 0.01 and 49.1 ml (median 0.1 ml, mean 1.5 ml). With respect to interobserver variability, the intrascan analysis did not reveal statistically significant differences (p > 0.05) between ULD-CT and SD-CT with broader limits of agreement for relative differences of RECIST measurements (-31.0 % + 27.0 % mean -2.0 % for SD-CT; -27.0 % + 38.6 %, mean 5.8 % for ULD-CT) than for volume measurements (-9.4 %, 8.0 %, mean 0.7 % for SD-CT; -13 %, 13 %, mean 0.0 % for ULD-CT). The interscan analysis showed broadened 95 % confidence intervals for volume measurements (-26.5 % 29.1 % mean 1.3 %, and -25.2 %, 29.6 %, mean 2.2 %) but yielded comparable limits of agreement for RECIST measurements. CONCLUSION: The variability of nodule volumetry assessed by semi-automated segmentation software as well as nodule size determination by RECIST appears to be independent of the acquisition dose in the CT source dataset. This is particularly important regarding size determination of pulmonary nodules in screening trials using low-dose CT data for follow-up imaging.

[Behaviour of titanium middle ear implants at 1.5 and 3 Tesla field strength in magnetic resonance imaging]. / Verhalten von Titan-Mittelohrimplantaten bei 1,5 und 3 Tesla Feldstärke in der Magnetresonanztomographie.

BACKGROUND: Investigations into the MRI compatibility of middle ear implants made from titanium alloys with 1.5 and 3.0 tesla MRI systems which are frequently used for imaging diagnostics. METHOD: 17 different middle ear (ME) implants (ossicular replacement prosthesis (ORP) and ventilation tubes) made from titanium were tested in vitro. Potential warming was determined via an MRI-compatible fibre optic temperature sensor under the influence of sequences with high-level high frequency impulses. An assessment of the attractive force of the implants was carried out placed on a Petri dish under vibration and floating on rubber-sponge (RS) in a water bath. RESULTS: No significant warming of the implants was observed with any of the used sequences at either 3 or 1.5 Tesla field strength (TF). With 3 TF, all 17 implants changed their position on the surface of the water and moved at a slow speed (0.0004-0.0014 m/s) towards the magnetic field. With 1.5 TF, the tested ME implants moved at a maximum speed of 0.0002 m/s and in the case of the ventilation tubes at 0.0005 m/s. CONCLUSION: No warming occurred in any of the tested middle ear implants at either 1.5 or 3 TF. The attractive forces exerted through the static magnetic field were overall low at 1.5 and 3 TF, indicating that no dislocation is to be expected if intraoperative anchoring is correctly conducted. Nevertheless, the indication for examination at 3 TF should be carefully considered due to the anatomically sensitive region.

Comparative evaluation of 2D time-of-flight and 3D elliptic centric contrast-enhanced MR venography in patients with presumptive cerebral venous and sinus thrombosis.

We retrospectively evaluated an elliptic centric ordered 3D (ec 3D) magnetic resonance venography (MRV) technique in comparison to 2D time-of-flight (2D TOF) MRV in patients with presumptive cerebral venous sinus thrombosis (CVST). Twenty-five patients (mean age 40.6 +/- 16.5 years) with presumptive CVST underwent cerebral MRI including 2D TOF and ec 3D MRV. Radiologic findings and clinical outcome were correlated. MRV studies were evaluated by two neuroradiologists in a blinded manner for image quality, assessment of various sinus, internal cerebral veins (ICV), vein of Labbé and Galen (VL/VG) as well as for additional imaging procedures required. Sensitivity/specificity of ec 3D MRV amounted to 85.7%/97.2% as compared with 2D TOF 71.4%/55.6 %. Ec 3D MRV performed superior in terms of image quality as well as assessment of all sinus and veins except for the straight sinus. Additional imaging procedures were less often required in ec 3D MRV studies (28% vs. 66% for 2D TOF MRV; P < 0.001). Interobserver agreement was significantly increased by using ec 3D MRV (93.1% vs. 70.9% of readings). The results of our study provide additional evidence for the superiority of ec 3D compared with 2D TOF MR venography for the diagnosis or exclusion of acute CVST in daily clinical practice.

[Problems of hyomandibulopexia in patients with OSAS]. / Probleme der hyomandibulären Pexie bei Patienten mit OSAS.

In cases of obstructive sleep apnea syndrome (OSAS) with intolerance of n-CPAP (nasal continuous positive airway pressure) treatment, hyoidthyroidpexia (synonym: hyoid suspension) has recently been advocated by some authors as a valuable surgical option. Despite a basically positive assessment, there is a risk of hindrance to the speaking and swallowing function. Moreover, the thyroid cartilage seems to be too weak for fixation of the hyoid with its complex muscular attachments. This reduces the likelihood of achieving positive long-term results. Considering aspects of preserving laryngeal function, we are reporting on 7 patients submitted to a hyomandibulopexia. This intervention counteracts the tendency of the tongue base to collapse by ventrolateral traction on the hypoglossal muscle via the severed greater horn of the hyoid. We have thus far had to correct our surgical procedure three times because of methodological problems in the postoperative phase. Specific problems with surgical materials like steel wire or Goretex are discussed. In conclusion, we explain why we consider a bone anchored Kevlar suture (FASTak of Arthrex) to be suitable for this operation. Considering functional aspects, our polysomnographic and phoniatric follow-up examinations point to a less traumatic surgical procedure with promising treatment results.

[Whole-body MR angiography: comparison of two protocols for contrast media injection]. / Ganzkörper-MR-Angiographie: Vergleich von zwei Protokollen zur Kontrastmittelinjektion.

PURPOSE: To compare two injection strategies for contrast media injection in whole-body MR angiography quantitatively and qualitatively with regard to contrast and image quality. MATERIAL AND METHODS: 40 patients were examined at 1.5 Tesla using either a single injection protocol or a double injection protocol with two separate bolus injections. Vessel regions I (supraaortic/thoracic), II (abdominal/pelvic), III (upper legs) and IV (lower legs) were examined in the following order: single injection: I, II, III, IV, double injection: I and IV after the first injection, II and III after the second bolus injection. Quantitative evaluation: SI measurements were carried out in 2 arteries per region. Contrast values were calculated. Qualitative evaluation: Evaluation of regions I-IV regarding vessel contrast, venous overlay and image quality on a five-point scale by two reviewers in consensus. The Mann-Whitney-U test was used to test the differences for significance. RESULTS: Quantitative evaluation: Using the double injection protocol, significantly higher contrast values in regions I and II and significantly lower contrast values in the subregions IIIa (upper part of III) and IVb (lower part of IV) were obtained (p < 0.05). The mean contrast values in subregions IIIb (lower part of III) and IVa (upper part of IV) were lower using the double injection protocol, but not significantly. Qualitative evaluation: Using the double injection protocol, region II was rated significantly higher (mean ratings: 3.55, 3.45 and 3.5 versus 2.7, 2.5 and 2.55; p < 0.05) and region III significantly lower (mean ratings: 3.1, 2, 2.5 versus 3.9, 3.1 and 3.55; p < 0.05) for all three examined criteria. When using the double injection protocol, ratings were significantly lower in region IV regarding vessel contrast and image quality (mean ratings: 2.4 and 2.15 versus 3.45 and 3.15; p < 0.05). The ratings regarding venous overlay in region IV showed no significant differences (mean ratings: 2.15 versus 2.75; p > 0.05). CONCLUSION: Due to the better results in the supraaortic/thoracic and abdominal/pelvic regions, the double injection protocol is preferred. However, both protocols require further improvement.

[Multislice computed tomographic myelography]. / CT-Myelographie in Mehrschichttechnik.

While magnetic resonance imaging (MRI) is the first line modality in depicting intramedullary spinal lesions, computed tomographic (CT) myelography has gained renewed attention due to the introduction of multislice scanning (MS-CT). Compared with conventional CT, MS-CT permits rapid, high-resolution imaging of various spinal pathologies with extended scan length. Although soft tissue contrast is inferior to that with MRI, MS-CT myelography performs best in detailed assessment of osseous pathologies, 3D imaging of orthopedic and anesthesiologic implants, and showing dural leakage and causes of CSF circulation impairment. Whenever MRI is not available or contraindicated, MS-CT myelography is the method of choice for evaluating spinal lesions.

[Effects of magnetic resonance tomography on upper eyelid implants]. / Einfluss der Magnetresonanztomographie auf Oberlidimplantate.

BACKGROUND: For the therapy of lagophthalmos in facial palsy, gold (99.99%), platinum (99.95%) and platinum/iridium (97%/3%) alloy weights are implanted into the upper eyelid. Investigations on the MRI compatibility of the different eyelid implants with 1.5 and 3.0 Tesla-MRT-systems, which are often used for the diagnosis of head and neck tumours, are still missing. METHODS: Three different eyelid implants made of pure gold, pure platinum and a platinum/iridium alloy were tested in vitro. As parameters, temperature changes, movements of the implants and picture artefacts of the different implants were determined using a 1.5 and 3.0 Tesla MR system. The deflection forces of the implants were evaluated by thread test, lying in a Petri dish and floating in a water bath. RESULTS: No rise in temperature was recorded in any implant. On the water surface, all three implants changed their positions and floated towards the magnetic field. The velocity of the implants increased in the 3.0 Tesla system. Increasing the frictional resistance by lying the implants in a Petri dish, there was no movement in the 1.5 or 3.0 Tesla systems. In addition, no movement of the implants could be observed in the thread test. All implants made few artefacts, with gold showing the least artefacts. CONCLUSION: MR imaging at 1.5 or 3.0 Tesla may be performed safely for warming up or dislocation of the implant in patients with eyelid implants made of pure gold, pure platinum or a platinum/iridium alloy.

Virtual endoscopy of the tympanic cavity based on high-resolution multislice computed tomographic data.

OBJECTIVE: This study was designed to assess the value of high-resolution multislice computed tomography (MSCT) data of the petrous bone for the virtual endoscopic visualization of the tympanic cavity. BACKGROUND: The recently introduced MSCT technology has improved spatial resolution in the z axis as well as scan speed in computed tomography. Three-dimensional rendering of high-resolution MSCT data of the petrous bone may be expected to provide endoluminal views of superior image quality, thus competing with transtympanic endoscopy (otoendoscopy). SETTING: This study was conducted at a university teaching hospital. MATERIALS AND METHODS: Cadaveric phantom studies in a MSCT scanner were performed to define a data acquisition protocol, combining adequate detail resolution with low tube current. Subsequently, the cadaveric phantom underwent otoendoscopy. The postprocessing parameters of the three-dimensional rendering protocol were chosen to produce views closely resembling the corresponding otoendoscopic images. High-resolution data from 18 patients with pathologic conditions of the middle ear, as suggested by clinical findings and assessment of cross-sectional data, were postprocessed using the volume rendering technique to generate standardized virtual endoscopic views. A total of 36 virtual endoscopic scans of the tympanic cavity were generated. RESULTS: With regard to intermediate and high-density structures, virtual endoscopic images, based on MSCT data, yielded endoluminal views closely resembling corresponding otoendoscopic views. Virtual endoscopy seems useful for imaging ossicular pathologic conditions such as dysplasia and chain disruption as well as for assessing patient status before and after otosurgery. CONCLUSION: MSCT data sets allow for generating virtual endoscopic views closely resembling otoendoscopic images. The technique is especially useful when ossicular pathologic changes are present as well as for preoperative and postoperative imaging of otologic procedures.

[Virtual rendering techniques in otologic imaging]. / Virtuelle Darstellungstechniken in der otologischen Bildgebung1.

UNLABELLED: Virtual postprocessing techniques combine the advantages of condensing the large amounts of data provided by high-resolution (HR) cross-sectional imaging modalities with those of three-dimensional (3D) imaging. The techniques and indications for virtual representations in imaging of the middle ear (ME), internal ear (IE), and cerebellopontine angle (CPA) are presented together with practical examples. MATERIAL AND METHODS: HR data sets acquired by computed tomography (CT) and magnetic resonance imaging (MRI) in patients with ME, IE, and CPA pathologies were transferred to a workstation via an internal network to generate endo- or extraluminal 3D views by means of the volume rendering technique (VRT). The source data were acquired using scanners and imaging protocols with the highest resolution available at present: a multislice spiral CT (MSCT) with a slice thickness of 0.5 mm and a reconstruction increment of 0.2 mm and a 3D CISS sequence with a slice thickness of 0.5 mm for MRI. RESULTS: Virtual endoscopy was superior to cross-sectional images for assessing ME pathologies like dysplasia, postoperative changes, and destructive bone processes with extensive soft-tissue involvement; fibrous obliterations of the internal ear and labyrinthine dysplasia were depicted with a superior image quality on 3D renderings compared to conventional reconstruction techniques. Virtual endoscopy of the CPA and external acoustic meatus (EAM) was helpful in detecting and visualizing neurovascular conflicts and in assigning small intrameatal tumors to components of the acousticofacial bundle. A common feature of all applications was that the large numbers of source images could be reduced to a few 3D reconstructions for documentation and optimized communication of the findings between the radiologist and otologist. CONCLUSION: Virtual rendering makes an important contribution towards establishing, presenting, and documenting the findings when certain otologic pathologies have to be assessed. It can be used for routine imaging and allows for more efficient handling of the large amounts of imaging data generated by high-resolution cross-sectional imaging modalities.

High-resolution petrous bone imaging using multi-slice computerized tomography.

Multi-slice computerized tomography (MSCT) is considered to provide superior image quality. We defined a data acquisition protocol for high-resolution (HR) temporal bone imaging using MSCT and assessed its impact on data acquisition and post-processing (PP). The data acquisition protocol was defined in cadaveric phantom studies performed by MSCT and subsequently applied to 38 patients referred for temporal bone assessment. The parameters image quality and diagnostic value of MSCT data were assessed for the cross-sectional source images as well as for 2-dimensional (2D) reformations and 3-dimensional (3D) reconstructions by 3 radiologists by comparison with incremental HR scans of 17 patients with suspected middle ear disorders. The data acquisition protocol yielded HR images with an excellent detail resolution and a comparable image quality of cross-sectional scans and related orthogonal reformations. MSCT achieved higher scores for image quality and diagnostic value (p < 0.001, t-test) than incremental HR CT with regard to both 2D and 3D reconstructions. MSCT improves the image quality of HR cross-sectional scans as well as that of 2D and 3D PP techniques in petrous bone imaging. The radiation exposure of the eye lenses is increased by MSCT as gantry angulation is not yet possible in the helical scan mode.

[Virtual otoscopy--technique, indications and initial experiences with multislice spiral CT]. / Virtuelle Otoskopie--Technik, Indikationen und erste Erfahrungen mit dem Mehrschicht-Spiral-CT.

UNLABELLED: We report the standardized postprocessing of high-resolution CT data acquired by incremental CT and multi-slice CT in patients with suspected middle ear disorders to generate three-dimensional endoluminal views known as virtual otoscopy. MATERIALS AND METHODS: Subsequent to the definition of a postprocessing protocol, standardized endoluminal views of the middle ear were generated according to their otological relevance. The HRCT data sets of 26 ENT patients were transferred to a workstation and postprocessed to 52 virtual otoscopies. RESULTS: Generation of predefined endoluminal views from the HRCT data sets was possible in all patients. Virtual endoscopic views added meaningful information to the primary cross-sectional data in patients suffering from ossicular pathology, having contraindications for invasive tympanic endoscopy or being assessed for surgery of the tympanic cavity. Multi slice CT improved the visualization of subtle anatomic details such as the stapes suprastructure and reduced the scanning time. CONCLUSION: Virtual endoscopy allows for the non invasive endoluminal visualization of various tympanic lesions. Use of the multi-slice CT technique reduces the scanning time and improves image quality in terms of detail resolution.