Assessment of quantitative computed tomographic cerebral perfusion imaging with H₂¹⁵0 positron emission tomography

Abstract

Assessment of quantitative cerebral blood flow on a conventional fast CT machine without the use of specialized equipment may be valuable in the investigation of acute stroke and head injury. We aimed to compare a single slice CT perfusion sequence with H2(15)O positron emission tomography using the sagittal sinus as an input function, a method that avoids unnecessary orbital irradiation. Eight patients were studied, two patients with gliomas, and six with arteriovenous malformations. The dynamic CT perfusion sequence was performed by acquiring the same 10 mm slice 10 times over 30 sec during a 50 ml bolus of intravenous contrast medium given at a rate of 7.5 ml sec-1 using a power injector. The CT perfusion studies were completed without complication. Co-registration was sub-optimal in one patient. Overall the correlation between the two methodologies was encouraging with an average r2 value of 0.524 for individual analyses. When two patients with high flow arteriovenous malformations were excluded the average r2 value increased to 0.640. The results of this CT perfusion methodology are encouraging. Having shown its feasibility, further studies in conditions with lower rates of cerebral blood flow are warranted.