RT Journal Article
SR Electronic
T1 A thresholding approach to improve metabolic volume assessment in PET/CT: Initial validation of methodology
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 177
OP 177
VO 50
IS supplement 2
A1 Zhang, Jun
A1 Hall, Nathan
A1 Lacey, Russell
A1 Teetor, Trevor
A1 Nayal, Olla
A1 Murrey, Douglas
A1 Bahnson, Eamonn
A1 Layman, Rick
A1 Martin, Jr, Edward
A1 Knopp, Michael
YR 2009
UL http://jnm.snmjournals.org/content/50/supplement_2/177.abstract
AB 177 Objectives It is common practice that an individualized threshold rather than a constant cutoff is used for assessing the tumor metabolic volume (MV). The study proposed a standardized methodology for accurate and reproducible MV determination at individualized cutoffs validated by phantom and patient PET/CT. Methods Specific phantoms & 44 lung cancer patients were scanned on a HI-Res PET/CT. 4 approaches were used to set delineation of MV at cutoffs of: (I) 50%, (II) 2.5SUV, (III) background and (IV) individualized thresholds determined by automatic background subtraction and correction. Known phantom volumes (PV) and CT volumes (CTV) were used for MV evaluation. A target threshold (TT) at which MV=CTV was used as the 2nd comparator. Results Significant differences were found between MVs determined by different approaches (p<0.001). The proposed method (IV) was consistently more accurate and reproducible than other approaches. The comparison to PV & CTV by (I) led to underestimation of MVs, while it revealed better results by(II). Method (III) yielded the largest variability. Compared to TT, it revealed threshold deviation of only 4±3% by (IV) however significantly increased by other methods (average: 18±9%). Conclusions The proposed method was shown to be superior in accuracy and robustness compared to current constant cutoff approaches. MV as a quantitative biomarker incorporating tumor metabolic activity might reflect overall disease burden more accurately than SUV and is of increasing importance to assess biological activities of therapies.