Abstract
652
Objectives: To evaluate the clinical diagnostic value of dual-phase 18F-fluoro-2-deoxy-D-glucose SPECT with coincidence using semi quantitative analysis and receiver operating characteristic curve (ROC) method for distinguishing the benign and malignant lesions.
Methods: Thirty patients with unknown lesions were enrolled in this study. All patients underwent dual-phase 18F-FDG SPECT/PET. The early images were obtained at 60 min post injection. And the patients were divided into 2 groups, one received delayed scans at 210 min after 18F-FDG injection and the other at 270 min. Lesion status was determined by pathologic findings or by clinical follow-up. The results were analyzed by qualitative and semi quantitative methods. For all lesions, the ratio of tumor to no tumor (T/NT) activity and the retention index (RI) of dual-phase images were calculated. ROC with calculation of area under the curve (AUC) was used to evaluate diagnostic ability of early imaging, delayed imaging and RI, respectively.
Results: Forty-eight lesions (30 malignant and 18 benign verified by pathologic findings or clinical follow-up) of 30 patients were detected by dual-phase imaging, in which there were 29 true positive results, 15 true negative, 3 false positive and 1 false negative. The sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value(NPV) of dual-phase imaging were 96.7%, 83.3%, 91.6%, 90.6%, and 93.8%, respectively. Those of early imaging and CT were 93.3%, 72.2%, 85.4%, 84.8%, 86.7% and 76.9%, 57.1%, 70.0%, 76.9%, 57.1%, respectively. The ratio of T/NT in all malignant lesions (except 1 false negative case) in delayed imaging were significantly increased (t=-3.071, P<0.01). However, there were no statistical differences in the ratio of T/B in benign lesions (t=0.398, P=0.695) between early and delayed imaging. The results of ROC curve shows that RI is significantly superior to early and delayed imaging. Combining RI with dual-phase imaging provided a higher diagnostic sensitivity, specificity, accuracy, PPV and NPV (96.7%, 88.9%, 93.8%, 93.5%, and 94.1%) than those of the early imaging and CT.
Conclusions: Dual-phase FDG-SPECT/PET provides benefit for differentiating benign from malignant lesions. And combined dual-phase imaging with ROC analytic method will improve the diagnostic specificity and accuracy.
- Society of Nuclear Medicine, Inc.