Localization of the posterior tympanum by using high-resolution CT image

Juru DUAN; Shuzhen LUO; Jiangping WEI; Mingzhi LI; Chunjiu LU

ABSTRACT

BACKGROUND:

Though the high-resolution CT(HRCT)could identify the inner structures of temporal bone.its tiny parts could hardly be observed accurately and clearly by the imaging examinations of auriculotemporal portion,with the influence of scanning layers as well as the partial volume phenomenon.However,it could be easily identified by the combination of thin sections and HRCT images.

OBJECTIVE:

To introduce a method which could locate the posterior tympanum and its neighboring structures using HRCT images and to provide an anatomical base for the imaging diagnosis and operative treatment on this area.DESIGN,TIME AND

SETTING:

The observations between the auriculotemporal sections and CT images were finished both in thc Department of Sectional and Imaging Anatomy,Medical College,Nanchang University and the Center of Medical lmageology.Jiangxi Provincial People's Hospital from July 2004 to June 2007.MATERIALSFifteen normal adult cadaveric heads(30 sides)which fixed by 100 g/L formaldehyde were scanned,with all the samples provided by the Department of Anatomy,Medical College,Nanchang University.The main equipment was GE Hi-speed Nx/i Sys CT equipment (GE Company,USA).

METHODS:

Tb obtain CT images of temporal bone(depth 1.00 mm,thickness 1.00 mm),15 normal adult cadaver heads were scanned by CT method taking callthomeatal line(CML)as the baseline.After that,specimens of auriculotemporal portion from temporal bone were taken,decalcified,desiccated and embedded.Sequential sections(thick 1.00 mm)were made.MAIN OUTCOME

MEASURES:

Comparing sequential sections with CT image,identified respectively the fossa incudis,chorda eminence,styloid eminence,tacial recess,sinus tympanl,ponticulus promontoni,suprameatal spine,etc.

RESULTS:

The depth of fossa incudas was about(1.49±0.05)mm,the distance from the fossa to pyramid segment of facial nerve was(5.67±0.1 4)mm.The distance from the medial wall of posterior tympanic sinus to the horizontal segment of facial nerve was(3.1 2±0.1 5)mm.The average distance from suprameatal spine to the vertical segment of facial nerve was (16.73±1.24)mm,to chorda tympani nerve(15.87±1.14)mm,to promontory(21.84±2.43)mm.

CONCLUSION:

Comparing the sectional antomy and CT image of auriculotemporal potion of temporal bone is valuable for the diagnosis and treatment of otopathy.