Ability of (18)F-DOPA PET/CT and fused (18)F-DOPA PET/MRI to assess striatal involvement in paediatric glioma.

PURPOSE

To assess the diagnostic performance of (18)F-DOPA PET/CT and fused (18)F-DOPA PET/MRI in detecting striatal involvement in children with gliomas.

METHODS

This retrospective study included 28 paediatric patients referred to our institution for the presence of primary, residual or recurrent glioma (12 boys, 16 girls; mean age 10.7 years) and investigated with (18)F-DOPA PET/CT and brain MRI. Fused (18)F-DOPA PET/MR images were obtained and compared with PET/CT and MRI images. Accuracy, sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) for striatal involvement were calculated for each diagnostic tool. Univariate and multivariate logistic analyses were applied to evaluate the associations between (18)F-DOPA PET/CT and fused (18)F-DOPA PET/MRI diagnostic results and tumour uptake outside the striatum, grade, dimension and site of striatal involvement (ventral and/or dorsal).

RESULTS

Accuracy, sensitivity, specificity, PPV, and NPV were 100 % for MRI, 93 %, 89 %, 100 %, 100 % and 82 % for (18)F-DOPA PET/MRI, and 75 %, 74 %, 78 %, 88 % and 58 % for (18)F-DOPA PET/CT, respectively. (18)F-DOPA PET/MRI showed a trend towards higher accuracy compared with (18)F-DOPA PET/CT (p = 0.06). MRI showed significantly higher accuracy compared with (18)F-DOPA PET/CT (p = 0.01), but there was no significant difference between MRI and (18)F-DOPA PET/MRI. Both univariate and multivariate logistic analyses showed a significant association (OR 8.0 and 7.7, respectively) between the tumour-to-normal striatal uptake (T/S) ratio and the diagnostic ability of (18)F-DOPA PET/CT (p = 0.03). A strong significant association was also found between involvement of the dorsal striatum and the (18)F-DOPA PET/CT results (p = 0.001), with a perfect prediction of involvement of the dorsal striatum by (18)F-DOPA PET/MRI.

CONCLUSION

Physiological striatal (18)F-DOPA uptake does not appear to be a main limitation in the evaluation of basal ganglia involvement.(18)F-DOPA PET/CT correctly detected involvement of the dorsal striatum in lesions with a T/S ratio >1, but appeared to be less suitable for evaluation of the ventral striatum. The use of fused (18)F-DOPA PET/MRI further improves the accuracy and is essential for evaluation of the ventral striatum.