Flat detector CT in the evaluation of brain parenchyma, intracranial vasculature, and cerebral blood volume: a pilot study in patients with acute symptoms of cerebral ischemia

Abstract

Background and purpose: The viability of both brain parenchyma and vascular anatomy is important in estimating the risk and potential benefit of revascularization in patients with acute cerebral ischemia. We tested the hypothesis that when used in conjunction with IV contrast, FD-CT imaging would provide both anatomic and physiologic information that would correlate well with that obtained by using standard multisection CT techniques.

Materials and methods: Imaging of brain parenchyma (FD-CT), cerebral vasculature (FD-CTA), and cerebral blood volume (FD-CBV) was performed in 10 patients. All patients also underwent conventional multisection CT, CTA, CTP (including CBV, CTP-CBV), and conventional catheter angiography. Correlation of the corresponding images was performed by 2 experienced neuroradiologists.

Results: There was good correlation of the CBV color maps and absolute values between FD-CBV and CTP-CBV (correlation coefficient, 0.72; P < .001). The Bland-Altman test showed a mean difference of CBV values between FD-CT and CTP-CBV of 0.04 ± 0.55 mL/100 mL. All vascular lesions identified with standard CTA were also visualized with FD-CTA. Visualization of brain parenchyma by using FD-CT was poor compared with that obtained by using standard CT.

Conclusions: Both imaging of the cerebral vasculature and measurements of CBV by using FD-CT are feasible. The resulting vascular images and CBV measurements compared well with ones made by using standard CT techniques. The ability to measure CBV and also visualize cerebral vasculature in the angiography suite may offer significant advantages in the management of patients. FD-CT is not yet equivalent to CT for imaging of brain parenchyma.

Fig 1.

A, Regions of interest for CBV measurements: 1) lateral basal ganglia; 2) frontal subcortical white matter; 3) occipital subcortical white matter; 4) thalamus; 5) corona radiata; 6) internal capsule, posterior limb. B, Bland-Altman plot displays slightly higher FD-CBV values (0.04 mL/100 mL) in comparison with CTP. C, Mean CBV values and SDs of the 6 regions of interest show only minimal deviations.

Fig 2.

CT (A) and FD-CT (B) show the good correlation of CBV color maps. CTA (C) and FD-CTA (D) display a high-grade stenosis (black arrows) of the left MCA (patient 4). Note the perfect delineation of this high-grade stenosis in FD-CTA.

Fig 3.

A, At initial scanning, the brain appears without any signs of stroke. B, FD-CT performed 24 hours later cannot visualize the stroke region. C, MR imaging also performed 24 hours later confirms infarct demarcation (arrows). D−F, MIP reconstruction of the CTA (D) and FD-CTA (E) corresponds perfectly with the DSA finding (F) of stenosis (arrow) in the distal M1 as well as the proximal M2 segments. Notice the sharp delineation of the vessels in FD-CTA in contrast to that in CTA.

Fig 4.

A and B, Comparison of CTP-CBV (A) with FD-CBV (B) demonstrates decrease of CBV in the region of the internal capsule, anterior limb. C, The region matches nicely with the MR image (Fig 3C).