Nagaraj Setty Holalkere MD, Presenter: Nothing to Disclose

Chethan K Belludi MBBS, Abstract Co-Author: Nothing to Disclose

Avneesh Gupta MD, Abstract Co-Author: Nothing to Disclose

Stephan Anderson MD, Abstract Co-Author: Nothing to Disclose

Jaroslaw Nicholas Tkacz MD, Abstract Co-Author: Nothing to Disclose

Jorge A. Soto MD, Abstract Co-Author: Nothing to Disclose

Our main purpose is to compare the diagnostic performance of qualitative and quantitative DWI with CSI technique in characterization of adrenal lesions using ROC analysis.

A total of 35 adrenal lesions in 34 subjects (mean age: 63 years, M:F=16:18) who had CSI and DWI were included in this retrospective study. Selection criteria included lesions that were ≥1cm and diagnosis established either by histopathology or imaging follow-up. The MRI was performed on 1.5T using axial echo planar spin-echo DWI sequence with b=0 and 600 mm2/sec; and T1-weighted fast-field echo sequence in In-(TE=4.2) and opposed-phase (TE=2.1) axial CSI. Analysis was performed independently by a reader blinded to clinical data. Qualitatively, lesions were compared to kidney and considered malignant if they were hyper or iso-intense on DWI and hypo-intense on ADC maps. ADC value (x10-3 mm2/sec) of the lesion was measured from the scanner generated maps. A cut-off ADC value of  ≥1.5 or ≥20% drop in signal intensity on opposed-phase image were considered for benignity on quantitative DWI and CSI respectively. ROC analysis including descriptive statistics and Mann Whitney U test were used for comparison.

The cohort included 74% benign and 26% malignant lesions. On ROC analysis, a higher area under the curve was achieved for qualitative DWI (0.94) as compared to quantitative DWI (0.76) and CSI (0.70). There was significant difference between qualitative DWI and CSI (p=0.04). There were no differences between qualitative and quantitative DWI (p=0.06) or quantitative DWI and CSI (p=0.59). The ADC of benign (1.7±0.6) and malignant (1.1±0.3) lesions were statistically different (p=0.01). The sensitivity, specificity and accuracy on qualitative DWI were 100%, 88% and 91%; on quantitative DWI were 77%, 65% and 68%; and on CSI were 55%, 87% and 77% respectively.

Quantitative DWI technique performs considerably better than the conventional chemical shift MRI in adrenal lesion characterization. A high sensitivity and accuracy were achieved with a comparable specificity on DWI. Although the quantitative ADC values were different among benign and malignant lesions, the diagnostic performance was comparable to CSI.

The molecular properties of diffusion-weighted imaging helps to characterize more lesions than chemical shift imaging and may offer additional benefits, especially in lipid poor adenomas.

Holalkere, N, Belludi, C, Gupta, A, Anderson, S, Tkacz, J, Soto, J, Diffusion-weighted Imaging (DWI) versus Chemical Shift Imaging (CSI): A Comparative Study on MRI Characterization of Adrenal Lesions Using Receiver Operating Characteristic Curve (ROC) Analysis.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8012802.html