Nielsen P, Engelhardt R, Fischer R, Heinrich HC, Langkowski JH, Bücheler E. Noninvasive liver-iron quantification by computed tomography in iron-overloaded rats. Invest Radiol 1992;27:312–317. RATIONALE AND OBJECTIVES. The benefit of computed tomography (CT) for the noninvasive determination of liver-iron concentration in human iron-overload diseases is a controversy in the literature. To study the sensitivity of CT for liver-iron quantification under experimental conditions, the authors measured single- and dual-energy CT numbers in vivo in the livers of iron-overloaded rats. METHODS. Thirty-five rats were subjected to an iron-rich diet for various periods, from 1 to 20 weeks, then scanned by single- and dual-energy CT. CT absorption was correlated to liver-iron content, which was determined by wet ashing and spectrophotometry RESULTS. Whereas a good correlation (r = 0.99 at 96 kV; r = 0.95 at 125 kV) between CT numbers and liver-iron concentration was found, CT was insensitive to low concentrations of iron. Dual-energy CT scanning results showed greater scattering in liver-iron quantification compared with single-energy CT. CONCLUSIONS. In rats, the sensitivity of single- and dual-energy CT is too low to quantify liver iron in the diagnostically most relevant region of mild liver siderosis (1–3 mg iron/g wet weight [w.wt]).