title: Comparison of two volumetric techniques for estimating liver volume using magnetic resonance imaging.
abstract: OBJECTIVE
  To compare the conventional technique of manual planimetry with the point counting technique for estimating liver volume from magnetic resonance imaging (MRI) data.
  
  
  METHODS
  This study comprised abdominal MR examinations of 38 consecutive patients. Evaluation of the images showed that liver size appeared normal in 27 patients and increased in 11. Liver volume was estimated using the techniques of planimetry and point counting. Both techniques were used in combination with the Cavalieri method of modern design stereology. A systematic slice sampling procedure was performed to estimate liver volumes using both volumetric techniques. The point counting technique was optimized by altering the point spacing of the grid. The agreement between the two techniques was found. Measurement repeatability of both volumetric techniques was also evaluated.
  
  
  RESULTS
  Both techniques allowed the same degree of optimization through the procedure of systematic section sampling. The application of a point spacing of 2.5 cm reduced the time measurement by a factor of 3.5 in relation with the time needed with planimetry. An excellent agreement was observed between the two volumetric techniques with mean differences (+/-SD) of 2.4 +/- 41.6 cm(3) and 8.5 +/- 49.8 cm(3) for the patients presenting normal and increased liver sizes, respectively. Both techniques were highly reproducible.
  
  
  CONCLUSIONS
  The point counting technique could be considered a more efficient approach than planimetry for estimating liver volume from MRI, due to its speed and simplicity.
authors: Department of Medical Physics, University Hospital of Iraklion, Iraklion, Crete, Greece.
authors: Michael
authors: M
authors: Mazonakis
authors: John
authors: J
authors: Damilakis
authors: Thomas
authors: T
authors: Maris
authors: Panos
authors: P
authors: Prassopoulos
authors: Nicholas
authors: N
authors: Gourtsoyiannis
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D016014:Linear Models; D008099:Liver / Q000033:anatomy & histology*; D008107:Liver Diseases / Q000175:diagnosis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results