Peter Florin Hahn MD, Presenter: Nothing to Disclose

Michael Austin Blake, Abstract Co-Author: Nothing to Disclose

Giles Walter Boland MD, Abstract Co-Author: Nothing to Disclose

Differences among CT scanners has been proposed as a potential source of uncertainty in the characterization of adrenal nodules based upon density. We compared scans of the same nodule performed on 2 different manufacturers' scanners to assess density measurement reproducibility.

Comparative searching of the radiology information system produced a list of patients with adrenal nodules scanned without IV contrast between 1/00 and 3/04 on both a Siemens 16 detector row and on a General Electric multi-row scanner, maintained according to manufacturers' specifications. Lesions that changed in size were excluded unless both scans were performed within 30 days. Largest lesion in each patient was measured if multiple. Two abdominal radiologists independently measured lesion density on a diagnostic workstation. Transitional nodules (benign 10HU on the other) were separately analyzed.

There were 26 patients (13M:13F, age 40-86 mean 65yr), with 4 malignant lesions and the other 22 stable for >9 months, including 1 myelolipoma (size 12-85 mean 25mm). GE scans were 4-row (22), 8-row (1), and 16-row (3). Mean difference between Siemens and GE measurements was .50, correlation .89 and .92). Correlation between the 2 readers was .99 for both Siemens and GE scan measurements. Reader 1 (resp. Reader 2) measured 7 (resp. 5) transitional lesions that were less than 10HU on GE but greater than 10 on Siemens, none the reverse (McNemar's test <.02 for Reader 1). Siemens slices tended to be thinner than GE on these 7 transitional cases compared to the other 19 (U-test p<.02), but there was no significant difference in nodule size (p=.21).

Slight differences between scanners in the critical 0-20HU range can affect diagnosis of adrenal nodules.

Hahn, P, Blake, M, Boland, G, Can Density Measurement Differences among CT Scanners Affect Diagnosis of Adrenal Nodules?.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4408610.html