Perfusion CT measurements in healthy cervical spinal cord: feasibility and repeatability of the study as well as interchangeability of the perfusion estimates using two commercially available software packages

Abstract

Our purpose was to examine the feasibility and reproducibility of perfusion CT studies in the cervical spinal cord and the interchangeability of the values obtained by two post-processing methods. The perfusion CT studies of 40 patients with neck tumours were post-processed using two software packages (Software-1: deconvolution-based analysis with adiabatic tissue homogeneity approach and Software-2: maximum-slope-model with Patlak analysis). Eight patients were examined twice for assessing the reproducibility of the technique. Two neuroradiologists separately post-processed the images with two arterial input functions (AIFs): (1) the internal carotid artery (ICA) and (2) the vertebral artery (VA). Maps of blood flow (F) in ml/min/100 g, blood volume (V) in ml/100 g, mean transit time (MTT) in seconds (s) and permeability (PS) in ml/min/100 g were generated. The mean F, V, MTT and PS (Software-1) with VA-AIF and ICA-AIF were 8.93, 1.12, 16.3, 1.88 and 8.57, 1.19, 16.85 and 1.94, respectively. The reproducibility of the techniques was satisfactory, while the V and MTT values (in Software-1) and the F and V values (in Software-2) were dependent on the site of the AIF (p >or= 0.03 and p=0.02, respectively). The interobserver agreement was very good. The significant differences in measurements for a single patient (%) using Software-1/Software-2 were +/-120%/110%, 90%/80%, 180% and 250%/130% for F, V, MTT and PS, respectively. Only F and PS values in the healthy tissue seemed to be interchangeable. Our results were in essential agreement with those derived by invasive measurements in animals. The cervical spine perfusion CT studies are feasible and reproducible. The present knowledge has to be validated with studies in spinal cord tumours in order to decide the usefulness of the perfusion CT in this field.

Computed Tomography Perfusion Assessment of Radiation Therapy Effects on Spinal Cord Hemodynamics

“…These quantitative estimates of human SC perfusion are in agreement with the results of a study that evaluated the feasibility and reproducibility of perfusion CT measurements in the cervical SC (14).…”

“…The application of a perfusion algorithm commonly used to calculate brain perfusion to the SC is appropriate because the SC, similarly to the brain, has a blood-brain barrier (BBB) and because contrast agent remains distributed within the vascular space, therefore reflecting BV (14). Selection of the AIF is of major importance in estimating perfusion parameters using the deconvolutionbased perfusion algorithm.…”

“…We applied the deconvolution-based perfusion algorithm, a widely available and robust method to obtain perfusion parameters (14,22). The application of a perfusion algorithm commonly used to calculate brain perfusion to the SC is appropriate because the SC, similarly to the brain, has a blood-brain barrier (BBB) and because contrast agent remains distributed within the vascular space, therefore reflecting BV (14).…”

“…The postprocessing method has been previously described and only relevant details will be provided here (14). One neuroradiologist experienced in postprocessing perfusion CT studies generated a set of data in each patient, using the larger vertebral artery (VA) and/or the VA that ran perpendicular to the acquisition plane as the arterial input vessel.…”

“…Quantitative assessment of SC perfusion has previously been conducted invasively in animals by exposing the SC and injecting radioactive materials (8)(9)(10). However, very few studies have noninvasively investigated SC perfusion in human beings using MR imaging techniques (11)(12)(13), and feasibility and reproducibility of computed tomography (CT) perfusion have only recently been published (14).…”