Abstract
Introduction
CT perfusion imaging (pCT) may be used to detect and monitor hemodynamic abnormalities due to cerebrovascular disease. The magnitude of variability in clinical measurements has been insufficiently evaluated. The purpose of this study was to measure the long-term variability of clinical pCT measurements in patients with cerebrovascular disease.
Methods
pCT parameters were calculated for the cerebral hemisphere contralateral to a carotid stenosis before and after stent treatment of stenosis in 33 consecutive patients. Mean transit time (MTT), cerebral blood flow (CBF), and cerebral blood volume (CBV) calculated from pCT data from both a small and large region of interest (ROI) using both manual and automated methods were compared before and after stent treatment. Differences between the first and second measurement were tested for statistical significance with at-test. Variability was calculated as the standard deviation of the differences divided by the mean of the pre- and post-stent treatment values. To adjust for proportional bias, the Bland–Altman analysis was applied.
Results
The differences between the two measurements of MTT, CBF, and CBV averaged 2.5 to 7.7% when a manual method was used and was higher with automatic methods (p > 0.07). The variability of the values was 18% for MTT, 19% for CBV, and 25% for CBF with the large ROI and the manual method of calculation. The magnitude was larger when the small ROI and automatic methods were employed.
Conclusion
Longitudinal measurements of MTT, CBV, or CBF by pCT may vary by 20–25%. To detect changes in treatment-related changes in perfusion, pCT studies must be designed to achieve statistical significance based on this variability.
Similar content being viewed by others
References
Hoeffner EG, Case I, Jain R et al (2004) Cerebral perfusion CT: technique and clinical applications. Radiology 231(3):632–644
Cenic A, Nabavi DG, Craen RA, Gelb AW, Lee TW (1999) Dynamic CT measurement of cerebral blood flow: a validation study. AJNR Am J Neuroradiol 20(1):63–73
Cenic A, Nabavi DG, Craen RA et al (2000) A CT method to measure hemodynamics in brain tumors: validation and application of cerebral blood flow maps. AJNR Am J Neuroradiol 21(3):462–470
Nabavi DG, Cenic A, Dool J et al (1999) Quantitative assessment of cerebral hemodynamics using CT: stability, accuracy, and precision studies in dogs. J Comput Assist Tomogr 23(4):506–515
Bisdas S, Nemitz O, Berding G et al (2006) Correlative assessment of cerebral blood flow obtained with perfusion CT and positron emission tomography in symptomatic stenotic carotid disease. Eur Radiol 16(10):2220–2228
Fiorella D, Heiserman J, Prenger E et al (2004) Assessment of the reproducibility of postprocessing dynamic CT perfusion data. AJNR Am J Neuroradiol 25(1):97–107
Kudo K, Terae S, Katoh C et al (2003) Quantitative cerebral blood flow measurement with dynamic perfusion CT using the vascular-pixel elimination method: comparison with H2(15)O positron emission tomography. AJNR Am J Neuroradiol 24(3):419–426
Gillard JH, Antoun NM, Burnet NG et al (2001) Reproducibility of quantitative CT perfusion imaging. Br J Radiol 74(882):552–555
Gobbel GT, Cann CE, Iwamoto HS, Fike JR (1991) Measurement of regional blood flow in the dog using ultrafast computed tomography: experimental validation. Stroke 22:772–779
Dewitt DS, Fatouros PP, Wist AO et al (1989) Stable Xenon versus radiolabeled microsphere cerebral blood flow measurements in baboons. Stroke 20:1716–1723
Kan Z, Phonqkitkarun S, Kobayashi S et al (2005) Functional CT for quantifying tumor perfusion in antiangiogenic therapy in a rat model. Radiology 237(1):151–158
van der Schaaf I, Wermer MJ, van der Graaf Y et al (2006) Prognostic value of cerebral perfusion-computed tomography in the acute stage after subarachnoid hemorrhage for the development of delayed cerebral ischemia. Stroke 37(2):409–413
Wintermark M, Ko NU, Smith WS et al (2006) Vasospasm after subarachnoid hemorrhage: utility of perfusion CT and CT angiography on diagnosis and management. AJNR Am J Neuroradiol 27(1):26–34
Furlan A, Eyding D, Albers GW et al (2006) The Dose Escalation of Desmoteplase for Acute Ischemic Stroke Study (DEDAS): further evidence of safety and efficacy 3 to 9 hours from stroke onset. Stroke 37:1227–31
Hacke W, Albers G, Al-Rawi Y et al (2005) The Desmoteplase in Acute Ischemic Stroke Trial (DIAS): a phase II MRI-based 9-hour window acute stroke thrombolysis trial with intravenous desmoteplase. Stroke 36(1):66–73
Field AS, Burdette JH, Maldjian JA, Yen YF, Moody DM (2003) Relationship between caffeine-induced changes in resting cerebral perfusion and blood oxygenation level-dependent signal. Laurienti PJ. AJNR Am J Neuroradiol 24(8):1607–1611, Sep
Field AS, Laurienti PJ, Yen YF, Burdette JH, Moody DM (2003) Dietary caffeine consumption and withdrawal: confounding variables in quantitative cerebral perfusion studies? Radiology 227(1):129–135, Apr
Sanelli PC, Lev MH, Eastwood JD et al (2004) The effect of varying user-selected input parameters on quantitative values in CT perfusion maps. Acad Radiol 11:1085–1092
Bland JM, Altman DG (1986) Statistical methods for assessing agreement between two methods of clinical measurement. Lancet i:307–310
Bland JM, Altman DG (1999) Measuring agreement in method comparison studies. Stat Methods Med Res 8:135–160
Bandera E, Botteri M, Minelli C, Sutton A et al (2006) Cerebral blood flow threshold of ischemic penumbra and infarct core in acute ischemic stroke: a systematic review. Stroke 37(5):1334–1339
Muir KW, Halbert HM, Baird TA, McCormick M et al (2006) Visual evaluation of perfusion computed tomography in acute stroke accurately estimates infarct volume and tissue viability. J Neurol Neurosurg Psychiatry 77(3):334–339
Wintermark M, Flanders AE, Velthuis B et al (2006) Perfusion-CT assessment of infarct core and penumbra: receiver operating characteristic curve analysis in 130 patients suspected of acute hemispheric stroke. Stroke 37(4):979–985
Conflict of interest statement
We declare that we have no conflict of interest.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Turk, A.S., Grayev, A., Rowley, H.A. et al. Variability of clinical CT perfusion measurements in patients with carotid stenosis. Neuroradiology 49, 955–961 (2007). https://doi.org/10.1007/s00234-007-0276-3
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00234-007-0276-3