Ashok Srinivasan MD, Presenter: Nothing to Disclose

Mohannad Ibrahim MD, Abstract Co-Author: Nothing to Disclose

Robert Parker, Abstract Co-Author: Nothing to Disclose

Suresh K. Mukherji MD, Abstract Co-Author: Consultant, Koninklijke Philips Electronics NV

To analyze differences in spectral HU curves generated on Gemstone spectral dual energy CT between benign post-Rx changes and malignant lesions in the head and neck  

IRB approval was obtained for this retrospective study which included 15 patients with benign post-Rx changes (Group 1) and 15 with pathologically proven malignancies, primary or recurrent (Group 2). These patients were chosen in a consecutive manner from 40 CT scans performed with GSI technology at our institution from 2009-2012. GSI enables generation of virtual HU for each tissue from 40-140 keV using dual energy technology. One board certified neuroradiologist placed ROIs in two locations in each patient: • ROI1 in the benign post Rx change or malignancy and • ROI2 in adjacent normal muscle to create two spectral HU curves (plot of virtual HU values versus virtual keV ) in each patient. Four curves were thus created: SHU-ROI1(B), SHU-ROI2(B), SHU-ROI1(M), SHU-ROI2(M). Nonlinear (exponential) regression was used to calculate the height, asymptote and power for each curve. In addition, differences (dif) and ratios (rat) of these model parameters between ROI1 and ROI2 were calculated within each subject. Parameters were then compared between groups 1 and 2 using a Wilcoxon Signed Rank test.  

All 15 patients in group 1 had been treated with chemoradiation + surgery for primary head and neck CA. In group 2, there were 2 patients with recurrent malignancies, 1 with metastatic tumor in the neck and 12 with primary tumors. There were significant differences between groups 1 and 2 for 3 parameters (ROI1 (height), dif(height) and rat(height)); {P <= 0.001 for all 3 parameters}. All three parameters were higher in group 2 compared to group 1. Using these parameters, AUC for separating groups 1 and 2 was > 0.88 for all three measures.  

Spectral HU curves generated using dual energy GSI are significantly different between post-Rx benign changes and proven maligant tissue, primary or recurrent. This technique holds promise in the non-invasive evaluation of suspected malignancy in the pre and post Rx neck. 

Spectral HU curves generated using GSI dual energy CT may help in the non-invasive differentiation of benign and malignant head and neck lesions, and reduce the need for unnecessary biopsies.

Srinivasan, A, Ibrahim, M, Parker, R, Mukherji, S, Differentiation of Benign Post Rx Changes and Malignant Processes in the Head and Neck Using Spectral HU Curves Generated on Gemstone Spectral Dual Energy CT.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12023236.html