[Virtual endoscopy with computed tomography of the anatomical structures of the middle ear].

Istituto di Radiologia, Università, Trieste.
La radiologia medica (Impact Factor: 1.34). 12/1997; 94(5):440-6.
Source: PubMed


We applied the new technique of virtual endoscopy to the middle ear because this anatomical area is characterized by favorable contrast.
CT examinations of the petrous bone were obtained using 1.5 mm thick 1 coronal axis slices, with 1 mm or 1.5 mm table feed, 120 kV, 140-170 mA and 2 s scan time. The images were reconstructed with the high resolution algorithm for bony structures and a small field of view (9.6 cm), separately for the right and left petrous bone. The images were then transferred on a workstation and processed with the Navigator virtual endoscopic software (General Electric). A threshold value ranging -350 to -600 HU was applied.
A series of images is acquired as the virtual endoscope moves from the external auditory canal to the middle ear cavity. Images of the anterior, medial, and posterior surfaces of the middle ear are presented. Different views of the ossicles are also presented. High quality images were always obtained for the middle ear structures, including the ossicles. CT endoscopy of the middle ear provides a new view of the anatomy of this complex area. It has some advantages and disadvantages; the former can be summarized as follows: -demonstration of areas which are difficult to show with endoscopy because of the presence of membrana tympani; -the virtual endoscope can be placed in several positions and therefore it can be inserted in all sites and tortuous places of anatomical cavity; -nice and effective demonstration of the ossicular chain including the stapes. The disadvantages are related to the fact that the endoscopic reconstruction (such as any other three-dimensional reconstruction) is a representation of surfaces where different densities are necessarily homogenized.
CT virtual endoscopy of the middle ear can currently be considered a complementary technique to conventional CT because it permits better anatomical detailing of this complex region.

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    ABSTRACT: Virtual endoscopy (VE) enables non-invasive 3D endoluminal imaging of the middle ear by post-processing of CT data. To optimise the clinical application a standardised approach was evaluated in normal and pathologic cases. Data acquisition was performed using multi-slice helical CT in 20 normal patients and 15 patients with malformation or trauma. Virtual endoscopy of the tympanic cavity and 3D images of the ossicles were generated using surface and volume rendering. Qualitative assessment of the representation of anatomical structures was performed in normal patients. In 15 pathological cases the diagnostic benefit was evaluated by comparing the 3D images to the 2D images and intra-operative findings. In all 35 cases 3D imaging was possible using the standardised approach. The ossicular chain as well as the bony and soft tissue structures of the tympanic cavity were visualised in 20 normal patients. In 7 of 8 patients with malformation and 1 of 7 patients with trauma the original diagnosis was changed by 3D imaging. Standardisation and evaluation of the method in normal patients is essential as it enhances the diagnostic reliability. Virtual endoscopy facilitates understanding of the complex anatomy of the middle ear. In cases of suspected malformation and confirmed trauma it is helpful for diagnosis and surgical planning.
    European Radiology 08/2002; 12(7):1684-92. DOI:10.1007/s00330-002-1313-6 · 4.01 Impact Factor
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    ABSTRACT: The 3D imaging of the middle ear facilitates better understanding of the patient's anatomy. Cross-sectional slices, however, often allow a more accurate evaluation of anatomical structures, as some detail may be lost through post-processing. In order to demonstrate the advantages of combining both approaches, we performed computed tomography (CT) imaging in two normal and 15 different pathological cases, and the 3D models were correlated to the cross-sectional CT slices. Reconstructed CT datasets were acquired by multi-slice CT. Post-processing was performed using the in-house software "3D Slicer", applying thresholding and manual segmentation. 3D models of the individual anatomical structures were generated and displayed in different colours. The display of relevant anatomical and pathological structures was evaluated in the greyscale 2D slices, 3D images, and the 2D slices showing the segmented 2D anatomy in different colours for each structure. Correlating 2D slices to the 3D models and virtual endoscopy helps to combine the advantages of each method. As generating 3D models can be extremely time-consuming, this approach can be a clinically applicable way of gaining a 3D understanding of the patient's anatomy by using models as a reference. Furthermore, it can help radiologists and otolaryngologists evaluating the 2D slices by adding the correct 3D information that would otherwise have to be mentally integrated. The method can be applied to radiological diagnosis, surgical planning, and especially, to teaching.
    Neuroradiology 10/2002; 44(9):783-90. DOI:10.1007/s00234-002-0784-0 · 2.49 Impact Factor
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    ABSTRACT: The aim of this study was to assess the role of virtual otoscopy and 3D ossicular reconstruction in the preoperative assessment of the ossicles in chronic suppurative otitis media. Thirty three patients of chronic suppurative otitis media with conductive deafness (air-bone gap > 35 dB) were included in this prospective study. All patients underwent axial multidetector CT. The axial CT data set was utilized for multiplanar 2D reformations as well as virtual otoscopy (VO) and 3D reconstructions. The imaging findings on these two techniques were read independently by two radiologists with respect to different parts of the ossicular chain by using a three-point scoring system and were compared with surgical findings. Both imaging techniques had comparable accuracy for evaluation of larger ossicular parts. However, for evaluation of stapes superstructure, VO/3D images were more accurate (85.29%) than 2D images (76.97%). Assessment of the lenticular process and incudostapedial joint by HRCT and 2D reformatted images was not reliable (P > 0.1); however, significant correlation (P < 0.001) was present between VO/3D and the operative findings. Virtual otoscopy improves evaluation of the ossicular chain particularly that of smaller structures such as the lenticular process, incudostapedial joint and stapes superstructure which may influence decisions regarding planning of ossiculoplasty.
    European Radiology 06/2009; 19(6):1408-16. DOI:10.1007/s00330-008-1282-5 · 4.01 Impact Factor
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