REVIEW ARTICLES  THE REPRODUCTIVE SYSTEM
Guest Editors: Freeman L. M., Bombardieri E. 

The Quarterly Journal of Nuclear Medicine 2002 June;46(2):122-30

Copyright © 2009 EDIZIONI MINERVA MEDICA

lingua: Inglese

Qualitative and quantitative comparison between images obtained with filtered back projection and iterative reconstruction in prostate cancer lesions of 18F-FDG PET

Etchebehere E. C. S. C. ^{1, 2}, Macapinlac H. A. ¹, Gonen M. ³, Humm K. ¹, Yeung H. W. D. ¹, Akhurst T. ¹, Scher H. I. ⁴, Larson S. M. ¹

¹ Nuclear Medicine Service, Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, USA 2 Division of Nuclear Medicine, Department of Radiology School of Medical Sciences, Campinas State University Unicamp, Campinas, Brazil 3 Department of Epidemiology and Biostatistics, and 4 Genito-Urinary Oncology Service, Department of Medicine Memorial Sloan Kettering Cancer Center, New York, USA

Back­ground. ­Recently, iter­a­tive recon­struc­tion ­with seg­mented atten­u­a­tion cor­rec­tions (­IRSAC) has ­been intro­duced for recon­struc­tion of 18F-FDG PET ­images. ­IRSAC pro­duces ­images ­that are ­more ­pleasing to the eye, but qual­ita­tive and quan­ti­ta­tive com­par­i­sons ­between ­IRSAC and fil­tered ­back pro­jec­tion (FBP) ­have not ­been ­reported for met­a­static ­cancer. ­Since quan­ti­ta­tive ­data has ­been ­widely ­used as an ­adjunct to inter­pre­ta­tion of PET ­scans, com­par­ison ­between ­IRSAC and FBP is ­needed. The pur­pose of ­this ­study was to com­pare ­image ­quality and the max­imum stan­dard­ized ­uptake value (SUVmax) ­obtained ­with FBP and ­with ­IRSAC in met­a­static ­lesions ­from pros­tate ­cancer.
­Methods. ­Twenty 18F-FDG PET ­scans (10 base­line and 10 ­follow-up) ­were per­formed in 10 ­patients ­with pros­tate ­cancer (­ages 66-85 yrs, ­mean 73.6 yrs). Acqui­si­tion ­began 45 min ­after injec­tion of 370 MBq of 18F-FDG. ­Images ­were recon­structed ­using FBP and ­IRSAC, and sub­mitted to ­visual and quan­ti­ta­tive anal­ysis. ­SUVmax was ­obtained for all metas­tases, on FBP and ­IRSAC. A ­Jaszczak ­phantom ­study was ­also per­formed.
­Results. ­IRSAC ­images ­showed ­better ­image ­quality ­than FBP espe­cially in ­regions of ­high ­activity con­cen­tra­tions. ­IRSAC ­detected 106 ­lesions on ­both base­line and ­follow-up ­scans, ­while FBP ­detected 100 and 95 ­lesions on base­line and ­follow-up ­scans, respec­tively. There­fore, 17 ­more ­lesions ­were ­seen on ­IRSAC. The ­mean ­SUVmax ­values on base­line ­scans for FBP and ­IRSAC ­were system­at­i­cally dif­ferent, at 4.46±1.99 and 5.13±2.67, respec­tively. On ­follow-up ­scans ­values ­were 3.89±1.72 for FBP and 4.29±1.93 for ­IRSAC. Com­par­ison of FBP ­with ­IRSAC on base­line and ­follow-up ­scans ­were sta­tis­ti­cally sig­nif­i­cant (base­line: ­paired “t”-­test p=0.0017; ­follow-up: ­paired “t”-­test p=0.0008). ­Phantom ­studies ­reveal ­that ­these dif­fer­ences can be ­explained by the ­type of recon­struc­tion fil­ters ­used, and ­IRSAC was ­more accu­rate ­than FBP.
Con­clu­sions. ­IRSAC ­detects ­smaller vol­umes in phan­toms, ­patient ­images are ­easier to inter­pret and ­more met­a­static ­lesions ­were ­detected. In addi­tion, ­IRSAC pro­vides repro­du­cible quan­ti­ta­tive ­data, com­par­able to ­data pro­vided by FBP. ­IRSAC SUV and FBP SUV are in ­close agree­ment but ­there was a sta­tis­ti­cally sig­nif­i­cant dif­fer­ence ­between the two, and there­fore ­threshold ­values of SUV ­will prob­ably ­need to be re-deter­mined ­with ­IRSAC, and are ­likely to be 10 to 19% ­higher ­than cur­rently ­reported.