Background:THAD is important sign of underlying liver disorder. Purpose:To evaluate role of triphasic CT in detecting causes and hemodynamics of transient hepatic attenuation difference that is important sign of an underlying liver disorder. Patients and methods:We retrospectively evaluated 40 patients with THAD, their age ranges were from 25-75 years old. The study was done over a period of 24 months (Jan 2018–Dec 2019), for each patient triphasic CT liver examination was performed, during the arterial, portal and delayed phases. We assessed attenuation of THAD area in different phases, morphology, relation to focal lesions and etiopathogenesis of THAD. Results: 27/40 patients with THAD presented with hyperdensity in the arterial phase and become isodense to the normal liver parenchyma in other phases, 3/40 patients with THAD presented with hyperdensity in the arterial phase, persist in the porto-venous phase and become isodense in the delayed phase. Different morphology of THAD was detected as follow; sectorial pattern (32), polymorphous pattern (5), diffuse (2) and multi-segmental THADs (1). 28/40 patients with THAD are related to focal lesion and12/40 patients with THAD unrelated to focal lesion. We detected etiopathogenesis of THAD as follow; 35/40 patients with THAD was due to portal hypoperfusion, 4/40 was due to primary increase arterial blood inflow and 1/40 was cryptogenic. Conclusion: THADs are benign entities associated to focal lesions or other diseases of the liver, radiologists should be familiar with it to avoid false-positive diagnosis of pseudo lesions and not to overestimate the extent of the disease.