Detection of recurrent glioma: A comparative study between 99mTc-GHA SPECT and 18F-FDG PET-CT

Objectives Purpose of this study was to compare the role of ¹⁸F-FDG PET-CT and ^99mTc-GHA SPECT in detecting recurrence in glioma patients.

Methods Ninety patients of clinically suspected recurrent glioma of various grades, previously treated with surgery and/or radiotherapy were evaluated using ¹⁸F- FDG PET/CT and ^99mTc-GHA SPECT. PET-CT was interpreted as positive in presence of hypermetabolic area or presence of CT lesion with any FDG uptake. GHA-SPECT images were interpreted as positive if abnormal tracer uptake noted in brain parenchyma. Sixty-three patients were available for follow-up re-evaluation with FDG PET/CT and ^99mTc-GHA SPECT after 6 months. Final outcome judged on the basis of biopsy report and/or clinical follow-up and other imaging results.

Results Fifty-nine patients were considered positive (biopsy in 5, death/clinical progression in 28 and progession on imaging in 26) while 31 were negative for recurrence. PET-CT scan was positive in 43, negative in 47 patients. ^99mTc-GHA SPECT was positive in 51, negative in 39 patients. Sensitivity of ^99mTc-GHA SPECT is 85%, much better than FDG PET-CT (70%), specificity (97%) and PPV(98%) are same in both. NPV is better in GHA SPECT (77% vs 63%). Overall diagnostic accuracy higher in GHA SPECT (89%) than PET-CT(80%). Differences between the two modalities statistically significant(p=0.035).

Conclusions Both ¹⁸F-FDG-PET –CT and ^99mTc-GHA SPECT were highly specific for detection of recurrence in glioma patients. However, ^99mTc- GHA-SPECT was found to be superior than¹⁸F-FDG-PET –CT as it has higher sensitivity and accuracy.