Diagnostic efficiency of SPECT/CT imaging in diagnosing solitary spinal metastasis and assessing effective radiation dosage

LIU Xue-hui; LI Hong-jun; YU Hong-xu; ZHOU Shuang; LOU ming

doi:10.3969/j.issn.1002-266X.2015.10.003

Abstract：Objective To evaluate the diagnostic efficiency of SPECT/CT in diagnosing indeterminate solitary spinal metastasis and assessing the effective radiation dosage .Methods A total of 67 patients with history of primary cancer who had solitary spinal lesions that could not be definitively diagnosed using 99m Tc-MDP bone whole body scan were enrolled and SPECT/CT was performed.The pathological results or follow-up(≥6 months) results of X-ray, CT, MRI or SPECT/CT were the standards of final diagnosis .The sensitivity, specificity, accuracy, positive predictive value and negative predic-tive value of SPECT , CT and SPECT/CT imaging were calculated respectively , and the diagnostic efficiency of SPECT/CT imaging was assessed by using receiver operating characteristic ( ROC) analysis in diagnosing indeterminate solitary spinal metastasis.The injected radionuclide activity in patients was calculated for the SPECT /CT inspection, and the dose-length product(DLP) of spiral CT examination in the same machine was also assessed .During the SPECT/CT examination, the effective radiation dosage of radionuclide received in patients with the same machine CT was estimated ( hereinafter referred as the effective dose).Results The sensitivity, specificity, accuracy, negative predictive value and positive predictive value for SPECT/CT imaging were 92.7%, 88.5%, 92.7%, 88.5%and 91.0%respectively, higher than that of SPECT and CT alone .The area under the ROC curve showed that SPECT/CT imaging had the highest diagnostic efficiency in diag-nosing indeterminate solitary spinal metastasis (AUC=0.950, P<0.01), and the following was CT and SPECT.The ef-fective doses were 4.01 ±0.35 mSv and 2.49 ±0.97 mSv when patients underwent SPECT/CT examination.Conclusions SPECT/CT imaging was more efficiency as compared with separate sets of SPECT and CT images .The effective radiation dose due to CT increases .