The goal in this study was to compare flat-panel detector (FD) CT with multislice (MS) CT in the visualization of intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), intraventricular hemorrhage, and external ventricular drains (EVDs) to evaluate the diagnostic quality and limitations of the new FD CT imaging modality.
Neuroimages obtained in 65 patients, including 24 with EVDs, were reviewed by 2 independent, experienced clinicians. Lesions in all patients were investigated with FD CT and MS CT. The numbers of slices positive for ICH and SAH were counted, and for ICH the diameter and area of the lesion was measured. The positioning of drains was assessed. The presence of ventricular blood was noted. Statistical analysis was performed by calculating the Pearson correlation coefficient (r) to evaluate the level of inter- and intraobserver agreement, and linear regression analysis was done to visualize the results of the numbers of ICH- and SAH-positive slices.
The authors found high interobserver agreement regarding the number of slices with evidence of ICH (r = 0.89 for MS CT, r = 0.78 for FD CT) and SAH (r = 0.88 for MS CT, r = 0.9 for FD CT). Thin layers of blood in the ventricles were not detected on FD CT in 36.4% of cases. Six of 7 perimesencephalic SAHs were not seen on FD CT scans. The EVDs could be assessed with both modalities in 83.3% of cases, but the position of the drain could not be determined with FD CT in 16.7% (4 of 24 cases).
In some respects, FD CT is of limited use for the visualization of intracranial hemorrhage. However, despite limited contrast resolution, ICH and EVDs can be reliably demonstrated. Perimesencephalic SAH and thin layers of blood in the occipital horns may not be detected using FD CT. Further evaluation and improvement of the image quality is necessary before FD CT will provide identical quality in comparison with MS CT.