David T. Fetzer MD, Presenter: Nothing to Disclose

Diana Kaya MD, Abstract Co-Author: Nothing to Disclose

Alessandro Furlan MD, Abstract Co-Author: Nothing to Disclose

Stamatis Kantartzis MD, Abstract Co-Author: Nothing to Disclose

Kyongtae Tyler Bae MD, PhD, Abstract Co-Author: Patent agreement, Covidien AG, Saint Louis, MO Patent agreement, Bayer AG, Pittsburgh, PA Expert Advisory Committee, Bracco Group, Princeton, NJ

To differentiate adrenal adenoma from metastasis on CECT by relating the attenuation of adrenal lesion to that of internal body tissue references on portal-venous phase (PVP).

The Institutional Review Board approved this retrospective study. Study cohort included 32 patients (7 males, mean age, 65 years; 25 females, mean age, 57) with 36 adrenal adenomas confirmed by pathology (n=17), chemical-shift MRI (n=6), or dedicated CT (n=13); and 5 patients (3 males, mean age, 71; 2 females, mean age, 65) with 8 metastases confirmed by growth at imaging follow-up (n=8), each with an available adrenal protocol CECT (i.e. with 10-min delay). Two readers in consensus measured PVP attenuation of adrenal lesions and liver, spleen, renal cortex, renal medulla, erector spinae muscle, aorta, and supra-renal IVC. In addition, attenuation of adrenal lesions on delayed (10 minutes) phase images was measured and relative percent lesion washout (RPW) calculated. Ratios of attenuation between adrenal lesions and other organs on PVP were calculated. For each ratio, ROC curves were obtained to assess best cut-off for differentiation of adrenal adenoma from metastasis. Area under the curve (AUC) for significant ratios was compared with that obtained based on RPW values.

The tissue attenuation ratios yielding highest specificity for diagnosis of adenoma on PVP images were adrenal lesion/muscle and adrenal lesion/spleen. Adrenal adenoma/muscle ranged from 0.43-3.91 (mean, 1.38), whereas adrenal metastases/muscle ranged from 0.85-1.42 (mean, 1.19); a cut-off ratio of 1.42 yielded specificity of 100% and sensitivity of 39% for differentiation of adrenal adenomas from metastases. Adrenal lesion/spleen ranged from 0.22-1.00 (mean, 0.58) for adenomas and 0.36-0.75 (mean, 0.54) for metastases; a cut-off ratio of 0.75 yielded specificity of 100% and sensitivity of 22%. For the diagnosis of adrenal adenoma, AUC of both adrenal lesion/muscle (0.56), and adrenal lesion/spleen (0.55) were significantly lower than AUC of RPW (0.94).

Some otherwise indeterminate adrenal lesions could be differentiated from metastasis on single-phase CECT by comparing lesion attenuation to splenic and muscle attenuation.

As adrenal lesions are commonly detected and frequently indeterminate on single-phase CECT, improved characterization without requirement of further work up is highly beneficial for patient care.

Fetzer, D, Kaya, D, Furlan, A, Kantartzis, S, Bae, K, Characterization of Adrenal Lesions at Single-Phase Contrast-enhanced CT (CECT): Use of Internal Body Tissue Attenuation as a Reference.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9012793.html