“On the Spot”: The Use of Four-Dimensional Computed Tomography Angiography to Differentiate a True Spot Sign From a Distal Intracranial Aneurysm

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 because 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. However, CTA is a snapshot in time. Four-dimensional (4D) CTA is a dynamic type of imaging and has emerged as a valuable imaging technique for different neurovascular disorders. Two patients with intracerebral hemorrhage both showed an assumed spot sign on CTA, suggesting active hemorrhage. Additional 4D-CTA showed true active hemorrhage in one patient and a distal intracranial aneurysm in the other. This aneurysm was initially falsely interpreted as a spot sign on conventional CTA. Our case findings show how 4D-CTA can discern active bleeding from aneurysmal hemorrhage in cases with hemorrhagic stroke. This finding proves the additional value of this relatively new technique, because the detected underlying disorders have different therapeutic consequences in the acute setting.