Diagnostic value of ¹⁸F-FDG PET/CT and MRI for intraspinal lesions: A comparative study

The aim of the present study was to investigate the value of the use of fluorine-18 (¹⁸F)-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) vs. magnetic resonance imaging (MRI) for the diagnosis of and differentiation between benign and malignant lesions in the spinal canal. For this purpose, a retrospective analysis was performed on the use of MRI and ¹⁸F-FDG PET/CT from January, 2017 to December, 2020, and the final diagnosis was obtained by performing a post-operative pathological examination or following a tissue biopsy (gold standard). The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of the two examination techniques were calculated and comparisons between them were made. The PET metabolic parameters, maximum standardized uptake value (SUVmax), peak standardized uptake value (SUVpeak), mean standardized uptake value (SUVmean), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) in the benign and malignant groups were calculated and compared, and the corresponding ROC curves were plotted. A total of 58 patients were enrolled, including 30 patients with malignant and 28 with benign lesions. The specificity of MRI was significantly higher than that of PET/CT (P<0.05). The sensitivity and negative predictive value of PET/CT were higher than those of MRI, although with no significant difference (P>0.05). The mean ± tandard deviation values of the PET metabolic parameters, SUVmax, SUVpeak, SUVmean, MTV and TLG, were 4.27±1.25, 3.49±1.07, 2.49±0.84, 6.58±5.36 and 17.12±15.50 in the benign, and 8.99±3.75, 7.35±3.26, 5.43±2.40, 12.25±12.18 and 112.41±85.98 in the malignant groups, respectively. The SUVmax, SUVpeak, SUVmean and TLG in the malignant group were higher than those in the benign group. The differences were all statistically significant (all P<0.0001). In distinguishing benign from malignant lesions, the area under the ROC curve (AUC) for SUVmax was 0.919, which was the largest, and the Youden index was 0.762, indicating 83.3% sensitivity and 92.9% specificity. The AUC for SUVpeak was 0.905 and that for SUVmean was 0.899. The aforementioned AUCs were significantly higher than those for MTV and TLG (0.609 and 0.786, respectively) (P<0.001). On the whole, the present study demonstrates that MRI is a reliable imaging technique for the diagnosis of intravertebral lesions. ¹⁸F-FDG PET/CT, as a noteworthy supplement to MRI, has a high sensitivity and accuracy for the qualitative diagnosis and identification of lesions. The synergistic effect of the two examination techniques may be helpful for a more accurate diagnosis.