What is the best method for reporting tumor diameter in vestibular schwannoma?
OBJECTIVE
Various methods have been used to report the tumor diameter of vestibular schwannomas. To clarify the most appropriate method to represent the tumor volume, tumor diameters according to various measuring methods were statistically compared with the actual tumor volume.


METHODS
Tumor volume was measured by three-dimensional constructive interference in steady state images in 52 unselected vestibular schwannomas. Pearson's correlation coefficient was obtained between the tumor volume and various tumor diameters, such as diameter parallel to the petrous edge (a); a pons-to-petrous diameter (b); ab, a maximum diameter of the portion in the cerebellopontine angle cistern (max CPA); a maximum diameter of the whole tumor (Max); and a diameter through an axis of the internal auditory canal (Axis). The tumors were divided into three groups on the basis of tumor volume, as follows: Group I (small, <0.5 cm(3)), Group II (medium, 0.5-2 cm(3)), and Group III (large, >2 cm(3)).


RESULTS
Max and Axis correlated best with the tumor volume in Group I and correlated least with the tumor volume in Group II. Any of these measurements was acceptable in Group III tumors. The max CPA consistently revealed good correlation with the tumor volume in all three tumor groups.


CONCLUSIONS
The max CPA measurement is the simplest and most appropriate way to represent the tumor volume in unselected tumors. Max or Axis is better only when small tumors (<0.5 cm(3) in volume) are being assessed-that is, those with a max CPA of less than 1 cm.
Tanaka
Yuichiro
Y
Department of Neurosurgery, Shinshu University School of Medicine, Matsumoto, Japan.
Hongo
Kazuhiro
K
Tada
Tsuyoshi
T
Kobayashi
Shigeaki
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001699:Biometry; D002530:Cerebellopontine Angle / Q000473:pathology; D007758:Ear, Inner / Q000473:pathology; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008432:Mathematical Computing; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000473:pathology*; D010579:Petrous Bone / Q000473:pathology; D010818:Practice Patterns, Physicians'; D015203:Reproducibility of Results; D012720:Severity of Illness Index