Ramit Lamba MBBS, MD, Abstract Co-Author: Nothing to Disclose

John P. McGahan MD, Abstract Co-Author: Nothing to Disclose

Tien Hong Tran DO, Abstract Co-Author: Nothing to Disclose

John M. Boone PhD, Presenter: Consultant, Varian Medical Systems, Inc Consultant, Artemis Inc Research funded, Varian Medical Systems, Inc Research funded, FUJIFILM Holdings Corporation Research funded, Hologic, Inc Research funded, Creatv MicroTech, Inc

Eugenio O. Gerscovich MD, Abstract Co-Author: Nothing to Disclose

J. Anthony Seibert PhD, Abstract Co-Author: Nothing to Disclose

To compare Hounsfield Unit (HU) measurements in abdominal organs between a 16, 64 and 128 channel CT scanner.

Hounsfield unit measurements of specific anatomical regions within the liver, spleen, pancreas, aorta, adrenal, kidney and body fat using a fixed region of interest were obtained for non-contrast CT exams performed on a General Electric (GE) Light Speed 16 channel CT scanner with similar measurements made for the same patients when repeat non-contrast CT’s were done on a Siemens Definition 64 channel and a Siemens Definition AS plus 128 channel CT scanner.

There were 224 measurements obtained on 26 patients which showed that HU measurements were lower for the Siemens 64 channel and the 128 channel CT scanner, compared to the GE 16 detector CT scanner in the various anatomical regions. The first column of the following table shows the HU difference and standard deviation of measurement for the GE 16 channel CT scanner compared with the Siemens Definition 64 channel scanner. The second column shows these differences between the GE16 channel scanner compared with the Siemens Definition 128 channel scanner.  Liver                  (11.1 + 6.7 HU)       (10.3 + 7.7 HU) Spleen                (9.7 + 6.9 HU)         (15.6 + 6.4 HU) Pancreas            (5.5 + 8.3 HU)         (4.0 + 9.5 HU) Aorta                 (0.2 + 8.9 HU)         (3.8 + 6.7 HU) Adrenal              (2.8 + 8.5 HU)         (1.9 + 4.7 HU) Kidney               (11.5 + 6.6 HU)       (11.5 + 6.7 HU) Body fat             (1.2 + 9.3 HU)         (1.2 + 9.5 HU)  

There are considerable differences of HU measurements in abdominal organs between CT scanners with 64 or 128 channels when compared to 16 channel CT scanners. The HU measurements are lower in abdominal organs with higher detector rows, making it difficult to compare HU from scanner to scanner.

HU measurements vary between different MDCT scanners and potential errors can result in unenhanced CT characterization of lipid rich adrenal adenomas, renal and liver cysts, using existing criteria.

Lamba, R, McGahan, J, Tran, T, Boone, J, Gerscovich, E, Seibert, J, Are Hounsfield Unit Measurements Different Among Different MDCT Scanners?.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9012786.html