[The petromastoid canal. A computed tomography investigation].
BACKGROUND
The petromastoid canal was first described in 1904 by Mouret and Rouviere. Since then, there have been very few publications about this canal. Modern high-resolution computed tomography (CT) enables a slice thickness of 1 mm and less, so the course of the petromastoid canal is visible. In this study the petromastoid canal is introduced and its dimensions measured.


METHODS
This study involved 316 CT scans of normal temporal bones of subjects age 19.6-84.2: 156 temporal bones of women and 160 temporal bones of men. The slice thickness of the CT scan was 0.5 mm, and 16-slice or 64-slice CT was used. The middle diameter, length, and angle of the petromastoid canal were measured.


RESULTS
The middle diameter of the petromastoid canal was 1.16+/-0.4 mm (0.25-2.5 mm), the length was 10.7+/-0.9 mm (4.25-16.1 mm), and the angle was 134.5+/-17.3 degrees (124-157 degrees).


CONCLUSIONS
The study shows for the first time the length and angle of the petromastoid canal. A slice thickness of at least 1 mm guarantees 100% imaging of the petromastoid canal. The petromastoid canal is an important anatomical landmark and is of clinical relevance.
Steinbach
S
S
Hals-Nasen-Ohren-Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, 81675, München. S.Steinbach@lrz.tum.de
Fitzthum
A
A
Reiser
M
M
Hundt
W
W
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013701:Temporal Bone / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult