Tomohiro Namimoto MD, Presenter: Nothing to Disclose

Shinichi Nakamura MD, PhD, Abstract Co-Author: Nothing to Disclose

Kosuke Morita, Abstract Co-Author: Nothing to Disclose

Daisuke Utsunomiya MD, Abstract Co-Author: Nothing to Disclose

Seitaro Oda MD, Abstract Co-Author: Nothing to Disclose

Yasuyuki Yamashita MD, Abstract Co-Author: Nothing to Disclose

The purpose of this study was to examine the usefulness of the 3D 3-point Dixon technique in detecting adrenal fat content as a marker of adrenal adenoma. Measurements of the 3-point Dixon technique were compared with conventional 2D dual echo chemical shift gradient recalled echo (GRE) technique.

There were 21 patients with 24 adrenal masses (21 adenoma and 3 non-adenoma) in this retrospective study. Eighteen masses in 17 patients were examined both MR imaging and CT (mean interval, 5.8 months). All MR imaging was performed with a 3.0-T system. 2D dual echo GRE MR imaging was performed with a TR of 250 msec, dual TEs of 1.2 and 2.3 msec. 3D 3-point Dixon MR imaging was performed with TR of 4.3 msec, triple TEs from 1.2 msec to 2.3 msec. Our study was subdivided into two parts. All 24 adrenal masses in 21 patients were compared quantitatively between dual echo GRE and 3-point Dixon techniques. Quantitative measurements of signal intensity (SI) changes between in-phase and opposed-phase images were computed as follows: SI index = (SIin - SIop)/ SIin, where SIip is SI on in-phase images and SIop is SI on opposed-phase images. Quantitative measurements of SI changes between water and fat images of 3-point Dixon were defined as WF index in this study. The WF index was calculated as follows: WF index =SIfat/ (SIwater + SIfat), where SIwater is SI on water images and SIfat is SI on fat images. Eighteen masses in 17 patients who were examined both MR imaging and CT were compared quantitatively between CT value and SI/ WF index. We used the Pearson correlation coefficient coefficient (R) to assess the strength of associations.

The SI index measured by 2D dual echo GRE was strongly correlated with that measured by 3D 3-point Dixon (R2 0.80) and WF index (R2 0.86). For comparison with CT value, SI index measured by 2D dual echo GRE (R2 0.71) was most correlate than that measured by 3D 3-point Dixon (R2 0.66) and WF index (R2 0.61). There was no overlap between adenomas and non-adenomas with all three indexes.

This study provided evidence that 3D 3-point Dixon MR imaging techniques offer an alternative to 2D dual echo GRE for fat detection of adrenal masses.

3D high resolution MRI with 3-point Dixon techniques offer an alternative to 2D conventional dual echo GRE for fat detection of adrenal masses. This technique is useful especially for small lesions.

Namimoto, T, Nakamura, S, Morita, K, Utsunomiya, D, Oda, S, Yamashita, Y, Fat Detection of Adrenal Lesions Using 3D 3-Point Dixon MR Imaging: Comparison with 2D Dual Echo Chemical Shift MR Imaging.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9010427.html