Estimation of spleen volume using stereological methods

The spleen is affected by many systemic diseases such as lymphoma, malaria, hairy cell leukemia, chronic lymphocytic leukemia, acute leukemia, thalassemia major, portal vein thrombosis and acute splenitis. A different volume increase is observed for the affected primary diagnosis. Determination of changes in spleen volume is critical to both diagnosing and evaluating the efficacy of treatment. Our study aimed to determine an effective volume calculation method for the spleen and to examine the Cavalieri principle. For this purpose, a cadaveric spleen was used. The actual volume of the spleen was measured by water overflow. Cross-sectional images of 1 mm, 3 mm, 5 mm and 10 mm thickness were obtained in three anatomical planes by computed tomography and magnetic resonance. The Cavalieri principle was used to calculate the volume on the screen in the same image magnification with the point counting scale in different frequencies. The effect of section thickness, point frequency, number of sections, total number of points counted and orientation, volume, error coefficient (CE) and calculation time were investigated. The spleen was then physically divided into parallel slices of 5 mm slice thickness. Cavalieri principle was used to calculate the volume. The results obtained were compared on the magnetic resonance images with the same slice thickness and the same point counting scale frequency and the effect of overprojection-underprojection was examined. Then, by using magnetic resonance images, the volume calculation was performed by Cavalieri principle by six different observers and it was observed that there was high agreement between observers (r=0.976). As a result, it was shown that the most effective volume calculation method could be performed in magnetic resonance imaging (reduction ratio = 0.795), 5 mm slice thickness and 15 mm point cointing scale frequency, below the 5 % error coefficient limits. Key words: Cavalieri's principle, Computed tomography, Efficiency, Magnetic resonance, Volume of spleen