Utility Of I 124 PET/CT In Identifying Radioiodine Avid Lesions In Differentiated Thyroid Cancer; A Systematic Review And Meta-Analysis

Abstract

Introduction

Diagnostic I-123 scans have been shown to underestimate the disease burden in differentiated thyroid cancer (DTC) when compared to I-131 post treatment scans, especially in children and patients who have had prior Radioiodine (RAI) therapy and/or distant metastasis.I-124 PET/CT has been shown to be highly effective in imaging DTC related metastatic disease.

Methods

We performed a systematic review and meta-analysis of studies investigating the sensitivity and specificity of I-124 PET/CT in identifying lesions amenable to RAI therapy as confirmed by I-131 post-treatment scanning.

Results

There were 141 patients and 415 lesions of DTC identified altogether. There was significant heterogeneity in the individual studies. The pooled sensitivity of the 124-I PET/CT in detecting lesions of differentiated thyroid cancer amenable to I-131 therapy was 94.2% (91.3-96.4% CI, p <0.01) and the pooled specificity was 49.0% (34.8 -63.4% CI,p<0.01). The pooled positive likelihood ratio (LR) was 1.43 (1.05-1.94 CI) and the pooled negative LR was 0.28 (0.15-0.53 CI). Overall, the diagnostic odds ratio was 7.90 (3.39–18.48 CI). There were a small but increased number of lesions identified by I-124 PET/CT that was not detected on post-treatment scan.

Conclusion

I-124 PET/CT is a sensitive tool to diagnose RAI avid DTC lesions, but also detects some new lesions that are not visualized on the post-treatment I-131 scan. Further carefully designed dosimetric studies may be required to fully establish the role of I-124 PET CT for identifying potential lesions for I131 therapy. I-124 PET/CT in DTC patients may have other applications in specific clinical situations .

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