Metabolic Tumor Volume Measured by F-18 FDG PET/CT can Further Stratify the Prognosis of Patients with Stage IV Non-Smal
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ORIGINAL ARTICLE
Metabolic Tumor Volume Measured by F-18 FDG PET/CT can Further Stratify the Prognosis of Patients with Stage IV Non-Small Cell Lung Cancer Su Woong Yoo & Jahae Kim & Ari Chong & Seong-Young Kwon & Jung-Joon Min & Ho-Chun Song & Hee-Seung Bom
Received: 1 July 2012 / Revised: 13 August 2012 / Accepted: 14 August 2012 / Published online: 5 September 2012 # Korean Society of Nuclear Medicine 2012
Abstract Purpose This study aimed to further stratify prognostic factors in patients with stage IV non-small cell lung cancer (NSCLC) by measuring their metabolic tumor volume (MTV) using F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT). Materials and Methods The subjects of this retrospective study were 57 patients with stage IV NSCLC. MTV, total lesion glycolysis (TLG), and maximum standardized uptake value (SUVmax) were measured on F-18 FDG PET/CT in both the primary lung lesion as well as metastatic lesions in torso. Optimal cutoff values of PET parameters were measured by receiver operating characteristic (ROC) curve analysis. Kaplan-Meier survival curves were used for evaluation of progression-free survival (PFS). The univariate and multivariate Cox proportional hazards models were used to select the significant prognostic factors. Results Univariate analysis showed that both MTV and TLG of primary lung lesion (MTV-lung and TLG-lung) were significant factors for prediction of PFS (P2.5 within the contouring margin were incorporated to define the tumor volumes (Fig. 1a–c). TLG was calculated by multiplying the mean SUV (SUVmean) of the primary tumor by metabolic volume of the tumor [8]. The SUVmax, MTV and TLG of primary lung lesions were recorded as SUVmax-lung, MTV-lung, and TLG-lung, respectively. Assessment of MTV, TLG, and SUVmax of all Tumor Lesions in Torso PET/CT In addition to the primary lung lesion analysis, MTV, TLG and SUVmax were also measured by torso PET/CT. We drew rectangular shaped volumes of interest (VOIs) fully encasing the primary tumor, regional lymph node and all distant metastases in the axial, coronal and sagittal PET/CT images. The boundaries of voxels presenting SUV intensity were automatically produced with a threshold of SUV exceeding 2.5. Normal organs which showed physiologic FDG uptake (such as the heart, stomach, liver, intestines, kidney, ureter and bladder) were manually subtracted from the VOI. Inflammation or other benign FDG-avid lesions were selected based on histopathological reports, other imaging modalities such as contrast-enhanced CT and response to therapy, and were excluded from the measurement (Fig. 1d–f). Finally, SUVmax, MTVand TLG in torso tumor lesions were recorded as SUVmax-torso, MTV-torso and TLG-torso, respectively. Statistical Analysis The threshold value allowing differentiation between the two groups of patients was selected by the receiver operating
Nucl Med Mol Imaging (2012) 46:286–293
characteristic (ROC) method. All PET parameters were compared with each of the dichotomized variables by t-test. Prog
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