Abstract
It is generally well accepted that transmission (TX)-based non-uniform attenuation correction can supply more accurate absolute quantification; however, whether it provides additional benefits in routine clinical diagnosis based on qualitative interpretation of 3D brain positron emission tomography (PET) images is still the subject of debate. The aim of this study was to compare the effect of the two major classes of method for determining the attenuation map, i.e. uniform versus non-uniform, using clinical studies based on qualitative assessment as well as absolute and relative quantitative volume of interest-based analysis. We investigated the effect of six different methods for determining the patient-specific attenuation map. The first method, referred to as the uniform fit-ellipse method (UFEM), approximates the outline of the head by an ellipse assuming a constant linear attenuation factor (μ=0.096 cm−1) for soft tissue. The second, referred to as the automated contour detection method (ACDM), estimates the outline of the head from the emission sinogram. Attenuation of the skull is accounted for by assuming a constant uniform skull thickness (0.45 cm) within the estimated shape and the correct μ value (0.151 cm−1) is used. The usual measured transmission method using caesium-137 single-photon sources was used without (MTM) and with segmentation of the TX data (STM). These techniques were finally compared with the segmented magnetic resonance imaging method (SMM) and an implementation of the inferring attenuation distributions method (IADM) based on the digital Zubal head atlas. Several image quality parameters were compared, including absolute and relative quantification indexes, and the correlation between them was checked. The qualitative evaluation showed no significant differences between the different attenuation correction techniques as assessed by expert physicians, with the exception of ACDM, which generated artefacts in the upper edges of the head. The mean squared error between the different attenuation maps was also larger when using this latter method owing to the fact that the current implementation of the method significantly overestimated the head contours on the external slices. Correlation between the mean regional cerebral glucose metabolism (rCGM) values obtained with the various attenuation correction methods and those obtained with the gold standard (MTM) was good, except in the case of ACDM (R 2=0.54). The STM and SMM methods showed the best correlation (R 2=0.90) and the regression lines agreed well with the line of identity. Relative differences in mean rCGM values were in general less than 8%. Nevertheless, ANOVA results showed statistically significant differences between the different methods for some regions of the brain. It is concluded that the attenuation map influences both absolute and relative quantitation in cerebral 3D PET. Transmission-less attenuation correction results in a reduced radiation dose and makes a dramatic difference in acquisition time, allowing increased patient throughput.
Similar content being viewed by others
References
Zaidi H, Hasegawa BH. Determination of the attenuation map in emission tomography. J Nucl Med 2003; 44:291–315.
Van Laere K, Koole M, Versijpt J, Dierckx R. Non-uniform versus uniform attenuation correction in brain perfusion SPET of healthy volunteers. Eur J Nucl Med 2001; 28:90–98.
Setani K, Schreckenberger M, Sabri O, Meyer PT, Zeggel T, Bull U. Comparison of different methods for attenuation correction in brain PET: effect on the calculation of the metabolic rate of glucose [in German]. Nuklearmedizin 2000; 39:50–55.
Zaidi H, Laemmli C, Allaoua M, Gries P, Slosman DO. Optimizing attenuation correction in clinical cerebral 3D PET: which method to use? J Nucl Med 2001; 42:195–196.
Zaidi H, Montandon M-L. Which attenuation coefficient to use in combined attenuation and scatter corrections for quantitative brain SPET? Eur J Nucl Med Mol Imaging 2002; 29:967–969.
Zaidi H, Sossi V. Correction for image degrading factors is essential for accurate quantification of brain function using PET. Med Phys 2003; in press.
Bergstrom M, Litton J, Eriksson L, Bohm C, Blomqvist G. Determination of object contour from projections for attenuation correction in cranial positron emission tomography. J Comput Assist Tomogr 1982; 6:365–372.
Weinzapfel BT, Hutchins GD. Automated PET attenuation correction model for functional brain imaging. J Nucl Med 2001; 42:483–491.
Stodilka RZ, Kemp BJ, Prato FS, Kertesz A, Kuhl D, Nicholson RL. Scatter and attenuation correction for brain SPECT using attenuation distributions inferred from a head atlas. J Nucl Med 2000; 41:1569–1578.
Zaidi H, Montandon M-L, Slosman DO. Magnetic resonance imaging-guided attenuation correction in 3D brain positron emission tomography. Med Phys 2003; 30:937–948.
Iida H, Narita Y, Kado H, et al. Effects of scatter and attenuation correction on quantitative assessment of regional cerebral blood flow with SPECT. J Nucl Med 1998; 39:181–189.
Arlig A, Gustafsson A, Jacobsson L, Ljungberg M, Wikkelso C. Attenuation correction in quantitative SPECT of cerebral blood flow: a Monte Carlo study. Phys Med Biol 2000; 45:3847–3859.
Stodilka RZ, Kemp BJ, Prato FS, Nicholson RL. Importance of bone attenuation in brain SPECT quantification. J Nucl Med 1998; 39:190–197.
Licho R, Glick SJ, Xia W, Pan TS, Penney BC, King MA. Attenuation compensation in99mTc SPECT brain imaging: a comparison of the use of attenuation maps derived from transmission versus emission data in normal scans. J Nucl Med 1999; 40:456–463.
Nicholson R, Doherty M, Wilkins K, Prato F. Paradoxical effects of the skull on attenuation correction requirements for brain SPECT. J Nucl Med 1988; 29:1316.
Turkington TG, Gilland DR, Jaszczak RJ, Greer KL, Coleman RE, Smith MF. A direct measurement of skull attenuation for quantitative SPECT. IEEE Trans Nucl Sci 1993; 40:1158–1161.
Zaidi H, Montandon M-L, Slosman D. Impact of the attenuation map on relative and absolute quantitation in 3D brain PET: assessment of 6 different methods. Conference proceedings of the VIIth International Meeting on Fully Three-dimensional Image Reconstruction in Radiology and Nuclear Medicine, 29 June–4 July 2003, Saint-Malo, France. Available on CDROM.
Watson CC, Jones W, Brun T, Baker K, Vaigneur K, Young J. Design and performance of a single photon transmission measurement for the ECAT ART. Proc IEEE Nuclear Science Symposium and Medical Imaging Conference 1997; 2:1366–1370.
Zaidi H, Diaz-Gomez M, Boudraa AE, Slosman DO. Fuzzy clustering-based segmented attenuation correction in whole-body PET imaging. Phys Med Biol 2002; 47:1143–1160.
Xu M, Cutler P, Luk W. An adaptive local threshold segmented attenuation correction method for whole-body PET imaging. IEEE Trans Nucl Sci 1996; 43:331–336.
Woods RP, Grafton ST, Watson JD, Sicotte NL, Mazziotta JC. Automated image registration. II. Intersubject validation of linear and nonlinear models. J Comput Assist Tomogr 1998; 22:153–165.
Zubal IG, Harrell CR, Smith EO, Rattner Z, Gindi G, Hoffer BP. Computerized 3-dimensional segmented human anatomy. Med Phys 1994; 21:299–302.
Watson CC. New, faster, image-based scatter correction for 3D PET. IEEE Trans Nucl Sci 2000; 47:1587–1594.
Friston K, Holmes A, Worsley K, Poline J, Frith C, Frackwiak R. Statistical parametric maps in functional imaging: a general linear approach. Hum Brain Mapp 1995; 2:189–210.
Evans AC, Collins DL, Mills SR, Brown ED, Kelly RL, Peters TM. 3D statistical neuroanatomical models from 305 MRI volumes. IEEE Conference Record of Nuclear Science Symposium and Medical Imaging Conference 1993; 3:1813–1817.
Hooper PK, Meikle SR, Eberl S, Fulham MJ. Validation of postinjection transmission measurements for attenuation correction in neurological FDG-PET studies. J Nucl Med 1996; 37:128–136.
Watabe H, Sato N, Deloar HM, Urayama SI, Oka H, Iida H. Acquisition of attenuation map for brain PET study using optical tracking system. Proc. IEEE Nuclear Science Symposium and Medical Imaging Conference, San Diego, CA, 4–10 October, 2001. 3:1458–1461.
Kinahan PE, Townsend DW, Beyer T, Sashin D. Attenuation correction for a combined 3D PET/CT scanner. Med Phys 1998; 25:2046–2053.
Swensson RG. Unified measurement of observer performance in detecting and localizing target objects on images. Med Phys 1996; 23:1709–1725.
Montandon M-L, Slosman DO, Zaidi H. Assessment of the impact of model-based scatter correction on18F-[FDG] 3D brain PET in healthy subjects using statistical parametric mapping. Neuroimage 2003; in press.
Braem A, Chesi E, Joram C, Garibaldi F, Joram C, Mathot S, Nappi E, Schoenahl F, Séguinot J, Weilhammer P, Zaidi H. Novel design of high-resolution parallax-free Compton enhanced PET scanner dedicated to brain research. Conference proceedings of the First International Meeting on Applied Physics, 15–18th October 2003. Badajoz, Spain; 2003:in press.
Goerres GW, Hany TF, Kamel E, von Schulthess GK, Buck A. Head and neck imaging with PET and PET/CT: artefacts from dental metallic implants. Eur J Nucl Med Mol Imaging 2002; 29:367–370.
Acknowledgements
This work was supported by the Swiss National Science Foundation under grants SNSF 3152-062008 and 3152A0-102143. The authors would like to thank Manuel Diaz-Gomez for performing the analysis of the data sets.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Zaidi, H., Montandon, ML. & Slosman, D.O. Attenuation compensation in cerebral 3D PET: effect of the attenuation map on absolute and relative quantitation. Eur J Nucl Med Mol Imaging 31, 52–63 (2004). https://doi.org/10.1007/s00259-003-1325-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00259-003-1325-8