Delayed CT angiography boosts imaging biomarker’s sensitivity

Adding a delayed CT angiography acquisition to an imaging biomarker in patients with spontaneous intracerebral hemorrhage increased the ability to predict hematoma expansion and a poor outcome, according to results published online Oct. 9 in Stroke.

CT angiography spot sign is a validated imaging biomarker whose presence predicts hematoma expansion in patients who experience spontaneous intracerebral hemorrhage, which is considered the most fatal form of stroke.

“The spot sign has proven itself as an attractive selection tool for therapeutic interventions in patients with ICH [intracerebral hemorrhage], in an attempt to halt or decrease hematoma expansion,” wrote Viesha A. Ciura, MD, of the radiology department at Massachusetts General Hospital in Boston, and colleagues.   

The researchers noted that the spot sign is dynamic and can be detected using a number of CT approaches. They wanted to see if a 90-second delayed CT would capture additional patients with a spot sign, increasing its sensitivity. To test that, they enrolled 121 patients between 2012 and 2013 at the hospital who had spontaneous intracerebral hemorrhage.

All patients underwent a noncontrast CT followed by CT angiography with a 90-second delayed acquisition, but only 74 received a follow-up noncontrast CT within 24 hours. Of those 74, 15 had a spot sign on the first, delayed or either CT angiography acquisitions. The overall rate of hematomas expansion was 15 percent, but that rate was much higher in spot sign-positive patients than the spot sign-negative patients (47 percent vs. 7 percent).

First-pass CT angiography had sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 55 percent, 94 percent, 60 percent, 92 percent and 88 percent, respectively. On delayed acquisition, they were 55 percent, 87 percent, 43 percent, 92 percent and 82 percent, respectively. With a spot sign on either CT acquisition, those measures were 64 percent, 87 percent, 47 percent, 93 percent and 84 percent, respectively.

At discharge, spot sign-negative patients scored a median 4 on the modified Rankin scale, with 79.6 percent having a poor outcome. Those with a spot sign on the first-pass, delayed or either CT angiography acquisitions had a score of 6 and 95.2 percent, 97 percent and 97.1 percent, respectively, had poor outcomes.  

Ciura et al observed that the spot sign in nearly half of the spot sign-positive patients was apparent only on delayed CT angiography. One patient in whom the spot sign was present on the first-pass acquisition did not demonstrate the spot sign on the delayed acquisition.

“In our experience, the 90-second delayed CTA [CT angiography] acquisition produces optimal and reproducible results,” they wrote.