[Simple volumetry of ischemic cerebral infarction using computerized tomography. Interobserver and method comparison].
OBJECTIVE
To study the reliability of brain infarct volume assessment with ruler and calculator.


METHODS
The brain infarctions of 45 patients were measured using 3 different methods on CT scans: In each section showing the lesion, the largest diameters were measured and multiplied by the slice thickness using the formula for A) an ellipsoid and B) a cylinder. The sectional volumes were summed up to calculate the entire lesion volume. C) Using the ellipsoid formula, the thickness of all sections showing the lesion were added and used as the third diameter which was multiplied with the two largest diameters of the lesion. The lesion volume was also assessed by planimetry on a workstation and served as reference. Using method A, two independent investigators measured 93 brain infarcts of 49 patients to assess the 95% confidence interval (CI) of agreement.


RESULTS
Compared to the reference, method A underestimated the volumes by -25%, method B overestimated the volumes by +12.5%, and method C by +18.6%. The mean difference between the two investigators was 2 ml. The 95% CI for small infarcts < or = 50 ml was 60%-150%, for larger infarcts +/- 26 ml.


CONCLUSIONS
This simple method is only reliable when changes in infarct volume exceeding 26 ml are to be detected.
Dieler
C
C
Abt. Neuroradiologie der TU Dresden. Christiane.Dieler@mailbox.tu-dresden.de
Fröhlich
E
E
Bourquain
H
H
Holle
R
R
von Kummer
R
R
D001921:Brain / Q000000981:diagnostic imaging*; D002544:Cerebral Infarction / Q000000981:diagnostic imaging*; D016001:Confidence Intervals; D006801:Humans; D008962:Models, Theoretical; D015588:Observer Variation; D012016:Reference Values; D014057:Tomography, X-Ray Computed / Q000379:methods
Einfache Volumetrie ischämischer Hirninfarkte mit der Computertomographie. Interrater- und Methodenvergleich.