“On the spot”: the use of 4D-CTA to differentiate a true “spot sign” from a distal intracranial aneurysm

Abstract Background Spontaneous intracerebral hemorrhage may arise from underlying abnormalities including aneurysms. Computed tomography angiography (CTA) is widely used for the detection of possible underlying causes, which is important since it may have immediate therapeutic consequences. In addition, CTA is used to detect the so-called “spot sign”, indicating active hemorrhage which carries a worse prognosis. CTA is, however, a snapshot in time. Four-dimensional CTA (4D-CTA) is a dynamic type of imaging and has emerged as a valuable imaging technique for different neurovascular disorders. Case description Two cases with intracerebral hemorrhage both showed an assumed “spot sign” on CTA, suggesting active hemorrhage. Additional 4D-CTA demonstrated true active hemorrhage in one case and a distal intracranial aneurysm in the other case. This aneurysm was initially falsely interpreted as a “spot sign” on conventional CTA. Conclusions Our case findings illustrate how 4D-CTA can discern active bleeding from aneurysmal hemorrhage in cases with hemorrhagic stroke. This proves the additional value of this relatively new technique, because the detected underlying disorders have different therapeutic consequences in the acute setting.