Single-photon-emission computed tomography

Gamma camera performance is determined primarily by collimator design and the characteristics of the scintillation material. In the case of a parallel colhmator, the colhmator design parameters are the hole diameter, their number, the distance between the holes (hole pitch), and the collimator thickness. The specific combination of these affects the sensitivity and the spatial resolution of the camera. Likewise, thick scintillating material limits spatial resolution, whereas a thin scintillation crystal yields lower sensitivities. 

Both sensitivity and resolution are determined by collimator design. Parallel-hole collimator geometry, although having a lower sensitivity than a small pinhole collimator, has a sensitivity and a field-of-view (FOV) that is 

Typical system spatial resolution and geometric sensitivity for pin-hole collimator apertures of 0.5 and 1 mm are plotted in Fig. 2.1(a). These calculations assumed an intrinsic spatial resolution of 1 mm and an aperture angle of 60°. As can be seen, the dependence of camera sensitivity decreases as the square of the subject to collimator aperture distance. Optimum configuration is thus achieved by placing the subject very close to the collimator aperture. Moreover, spatial resolution degrades approximately linearly with subject to collimator distance. 

LSO (LuaSiOsrCe) (23) or GSO (Gd2Si05 Ce) (24). A summary of commonly used PET and SPECT scintillation material is presented in Table 2.1. 

Scintillation material Density (g/cm ) Effective atomic number Primary decay constant (ns) Emission intensity (%NaI) Entission wavelength (nm) Attenuation coefficient at 511 keV (cm ) 

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Single photon emission computed tomography (SPECT)... 

Single-photon emission computed tomography (SPECT) studies are acquired by rotating the y-camera around the patient s long axis. These data are then used to reconstmct the radioactivity distribution in three dimensions. This may be displayed as sHces of radioactivity concentration or rendered so as to present the appearance of a soHd volume. 

Sakai F, Nakazawa K, Tazaki Y, Ishii K, Hino H, Igarashi H, Kanda T. Regional cerebral blood volume and hematocrit measured in normal human volunteers hy single-photon emission computed tomography. J Cereb Blood Flow Metab 1985 5 207-213. 

Innis, R., Baldwin, R.M., Sybirska, E., Zea, Y., Laruelle, M., Al-Tikriti, M., Chamey, D., Zoghbi, S., Wisniewski, G., Hoffer, P., Wang, S., Millius, R., and Neumeyer, J., Single photon emission computed tomography imaging of monoamine uptake sites in primate brain with [123I]CIT, Eur. J Pharmacol., 200, 369, 1991. 

Shaya, E.K., Scheffel, U., Dannals, R.F., Ricaurte, G.A., Carroll, F.I., Wagner, H.N., Jr., Kuhar, M.J., and Wong, D.F., In vivo imaging of dopamine reuptake sites in the primate brain using single photon emission computed tomography (SPECT) and iodine-123 labeled RTI-55, Synapse, 10, 169, 1992. 

Merkel OM, Librizzi D, Pfestroff A, Schurrat T, Buyens K, Sanders NN, De Smedt SC, Behe M, Kissel T (2009) Stability of siRNA polyplexes from poly(ethylenimine) and poly (ethylenimine)-g-poly(ethylene glycol) under in vivo conditions effects on pharmacokinetics and biodistribution measured by Fluorescence Fluctuation Spectroscopy and Single Photon Emission Computed Tomography (SPECT) imaging. J Control Release 138 148-159... 

Malison, R. T., Price, L. H., Berman, R. et al. Reduced brain serotonin transporter availability in major depression as measured by [123I]-2(3-carbomethoxy-3(3-(4-iodophenyl)-tropane and single photon emission computer tomography. Biol. Psych. 44 1090-1098,1998. 

POSITRON EMISSION TOMOGRAPHY (PET) AND SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY (SPECT) 944... 

Weinberger, D. R., Gibson, R., Coppola, R. et al. The distribution of cerebral muscarinic acetylcholine receptors in vivo in patients with dementia. A controlled study with 123IQNB and single photon emission computed tomography. Arch. Neurol. 48 169-176,1991. 

Volkow, N. D., Fowler, J. S. and Wang, G. J. Positron emission tomography and single-photon emission computed tomography in substance abuse research. Semin. Nucl. Med. 33 114-128,2003. 

DeKosky, S. T., Shih, W. J., Schmitt, F. A et al. Assessing utility of single photon emission computed tomography (SPECT) scan in Alzheimer disease correlation with cognitive severity. Alzheimer Dis. Assoc. Disord. 4 14—23,1990. 

Sharma V, Piwnica-Worms D (2005) Monitoring Multidrug Resistance P-Glycoprotein Drug Transport Activity with Single-Photon-Emission Computed Tomography and Positron Emission Tomography Radiopharmaceuticals. 252 155-178 Shinkai S, see Ishi-i T (2005) 258 119-160... 

Scopolamine increases cerebral blood flow to lateral occipital cortex bilaterally and to the left orbitofrontal region (Grasby et al. 1995). Decreases are seen in the right thalamus, precuneus, and lateral premotor areas bilaterally. When normal subjects are chronically administered scopolamine, there is a 12% increase in cerebral blood flow on single photon emission computed tomography (SPECT), but a decrease in cerebral muscarinic binding (Sunderland et al. 1995). On the other hand, acute administration dose-dependently reduces cortical blood flow, which is maximal in frontal cortex (Gitelman and Prohovnik 1992 Prohovnik et al. 1997). 

PET positron emission tomography, /V intravenous, nic nicotine, DV volume of distribution, DA dopamine. cd caudate, put putamen, SPEC single photon emission computed tomography, DAT dopamine transporter, p-CTT 2 p-catbomethoxy-3 p-(4-iodophenyl)-tropane, 5-HT serotonin... 

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