Kumaresan Sandrasegaran MD, Presenter: Research grant,Bayer AG

Aashish Patel MD, Abstract Co-Author: Nothing to Disclose

Raja Ramaswamy, Abstract Co-Author: Nothing to Disclose

Victor P. Samuel, Abstract Co-Author: Nothing to Disclose

Mark Steven Frank MD, Abstract Co-Author: Nothing to Disclose

Benjamin G. Northcutt MD, Abstract Co-Author: Nothing to Disclose

Isaac R. Francis MD, Abstract Co-Author: Research grant, General Electric Company Consultant, General Electric Company Research grant, Bayer AG Consultant, Bayer AG

To assess the role of diffusion-weighted MRI in characterizing adrenal masses.

A retrospective review of the MRI database from August 2007 to July 2009 was performed for this IRB-approved and HIPAA-compliant study. The MRI examinations of the 48 patients, with 49 lesions, were reviewed independently and blindly by two experienced abdominal radiologists who measured the signal intensities on in-phase and opposed-phase T1-weighted imaging, and apparent diffusion coefficient (ADC). ADC measurements and quantitative parameters of chemical shift imaging [signal intensity index (SII) and adrenal-to-spleen ratio (ASR)] were assessed separately, and in combination. Lesions with indeterminate SII (< 16.5%) were considered benign if ADC was = or > 1.0 x 10-3 mm2/s, and malignant if ADC was < 1.0 x 10-3 mm2/s. Stepwise logistic regression analysis and receiver operating characteristic curves (ROC) were performed.

There were 12 malignant and 37 benign lesions. On multivariate analysis, the only significant predictor of lesion status was SII from reviewer 2 (p=0.05), and ADC values were not found to be useful. On ROC analysis, there was no significant difference in area-under-curve of ADC, SII, ASR or the combined SII and ADC assessment. In lesions indeterminate on SII, ADC > 1.50 x 10-3 mm2/s were found only in benign lesions and 9 of 11 lesions with ADC < 1.0 x 10-3 mm2/s were malignant.

ADC values, in general, are not useful in differentiating adrenal lesions. However, when applied to lesions that are indeterminate on SII, they may help in differentiating a subset of benign and malignant lesions.

DWI may be used as part of the protocol in determining the nature of an adrenal nodule. When ADC is > 1.50 x 10-3 mm2/s in lipid poor lesions, an adenoma may be confidently diagnosed.

Sandrasegaran, K, Patel, A, Ramaswamy, R, Samuel, V, Frank, M, Northcutt, B, Francis, I, Characterization of Adrenal Masses with Diffusion-weighted Imaging.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9005793.html