Virtual endoscopy 3-D findings of the middle ear based on 64-detector spiral CT data

Objective To assess the value of 64-detector spiral CT for the virtual endoscopy(VE) of normal middle ear and the three-dimensional reconstruction of ossicular chain.Methods 33 subjects were examined by 64-detector spiral CT.The obtained data was transferred to GE Advantage Workstation via an internal Dicom network for post-processing. CTVE, SSD of ossicular chain and the oblique reconstruction of stapes were processed on 35 ears,and were compared with anatomy and coronal and axial CT film.Results The structures of handle and head of malleus,body and long limb of incus, body and limbs of of stapes, promontory, fossa of round window, oval window, auditory tube, hypotympanon, epitympanic recess ,pyramidal eminence and horizontal semicircular canal were clearly displayed in 100%(35/35). CTVE showed the location of incudostapesial joint, base of stapes and facial nerve tube in 100%(35/35). CTVE clearly showed the anterior limb of stapes in 68.6%(24/35), the posterior limb of stapes in 74.3%(26/35). CTVE had a low differentiation for the ligament of mallus and incus. CTVE showed the facial recess in 65.7%(23/35).CTVE showed the ponticulus and subiculum of retrotympanium in 8.6%(3/35),respectively.The representation of SSD of ossicular chain and oblique reconstruction of stapes: The SSD of normal ossiular chain showed all the structures of ossicles in 100%(35/35), especially the anterior and posterior limbs and base of stapes.Conclusion CTVE can clearly and three-dimensionally show most structures of normal middle ear. SSD of ossicular chain and the oblique reconstruction of stapes can wholely show the ossicular chain. The imaging of CTVE, SSD of ossicular chain and reconstruction of stapes of 64-detector spiral CT is clear and tridimensional with a short time, and can be applied in clinical examination.