Synchrotron Radiation Computed Tomography with combined high spatial and temporal resolutions

M. Ruat (1) , J.-F. Adam (2, 1) , C. Nemoz (1) , D. Reynard (2) , P. Deman (3) , T. Brochard (1) , C. Ponchut (1)

1 ESRF - European Synchrotron Radiation Facility
2 GIN - [GIN] Grenoble Institut des Neurosciences
3 Department of Oral Biological and Medical Sciences

Studying the hemodynamics in brain is of particular interest for the diagnosis, the understanding and the management of pathologies such as ischemia [1], tumors [2], and traumas [3]. For malignant glioma, it has been shown that perfusion parameters are correlated to the tumor aggressivity [4], and can be used for the treatment outcome prognosis [5]. Quantitative measurements have to be compared between various imaging days and between patients. Synchrotron Radiation Computed Tomography (SRCT) is the gold standard to measure in vivo contrast agent concentrations with high accuracy and precision owing to the characteristic of the beam and performances close to theoretical limits: high flux, nearly parallel and monochromatic x-ray beams [6,7]. In addition to being quantitative, SRCT [8] could be greatly improved with both a high temporal and spatial resolution, which we assumed would be combined using the Maxipix-CdTe detector under development at ESRF [9]. This detector features a monolithic 1 mm thick single crystal CdTe sensor (99% efficient at energies up to 60 keV) hybridised to a matrix of 3x1 Timepix chips, giving a total area of 768x256 pixels at 55 μm pitch (45 x 15 mm2). Its tomographic spatial resolution is of 0.06x0.06x0.06 mm3. The high efficiency of the detector as well as its background noise suppression enabled low dose imaging (200mGy/s). Monochromatic X-rays at 35 and 51 keV were used. 360° tomography images have been taken over 2s, 6s, and 60s. Reconstruction of the tomographic slices was conducted using PyHST package developed at ESRF. A software extension has been developed to correct for defective or unstable pixels. The results were compared to images acquired with the reference 1D germanium detector. We have successfully retrieved iodine contrast agent quantification for both steady-state protocol and dynamic contrast-enhanced perfusion imaging, with phantoms. In vivo SRCT imaging in rats bearing brain tumors also proved successful, following up the iodine uptake for 25 minutes. We foresee low dose high resolution volumic perfusion measurements, relying on enhanced frame rates and synchronization accuracy as well as improved image reconstruction techniques. References [1] Klotz E, et al., European Journal Of Radiology. 1999; 30: 170-84. [2] Eastwood JD, et al., Neuroradiology. 2003; 45: 373-6. [3] Wintermark M, et al., Radiology. 2004; 232: 211-20. [4] Roberts HC, et al., AJNR Am J Neuroradiol. 2000; 21: 891-9. [5] Cao Y, et al., International Journal Of Radiation Oncology Biology Physics. 2006; 64: 876-85. [6] Adam, J. F., H. Elleaume, et al., Journal Of Cerebral Blood Flow And Metabolism 23(4): 499-512 (2003). [7] Adam, J. F., C. Nemoz, et al., Journal Of Cerebral Blood Flow And Metabolism 25(2): 145-153 (2005). [8] Le Duc G. et al., European Radiology 10 : 1487-1492 (2000). [9] Ruat M and Ponchut C, IEEE Trans. Nucl. Sci. 59(5): 2392-2401 (2012)

Domaines: Imagerie

M. Ruat, J.-F. Adam, C. Nemoz, D. Reynard, P. Deman, et al.. Synchrotron Radiation Computed Tomography with combined high spatial and temporal resolutions. Medical Applications of Synchrotron Radiation MASR 2015, Oct 2015, Villard de Lans, France. ⟨hal-01286631⟩