Relationship Between Dual Time Point FDG PET/CT and Clinical Prognostic Indexes in Patients with High Grade Lymphoma: a Pilot Study

Abstract

Purpose

This study investigated the correlative relationship between metabolic parameters estimated from dual time point 2-deoxy-2-[¹⁸F] fluoro-D-glucose (¹⁸F-FDG) positron emission tomography/computerized tomography (PET/CT) and the clinical tools predicting the outcome of a lymphoma. We also measured metabolic and volumetric alterations between early and delayed ¹⁸F-FDG PET/CT in patients with high grade lymphoma (HGL).

Methods

The samples were 122 lymph nodes and extralymphatic lesions from 26 patients diagnosed with HGL. All patients were applied to the International Prognostic Index (IPI), Ann Arbor stage, and revised IPI as clinical prognostic parameters. ¹⁸F-FDG dual time point PET/CT (DTPFP) consisted of an early scan 1 h after ¹⁸F-FDG injection and a delayed scan 2 h after the early scan. Based on an analysis of DTPFP, we estimated the standardized uptake value (SUV) of tumors from the early and delayed scans, retention index (RI) representing the percentage change between early and delayed SUV, and metabolic volume different index (MVDI) calculated using metabolic tumor volumes (MTV).

Results

RI_max showed a multiple positive correlative relationship with stage and IPI in lesion-by-lesion analysis (p < 0.01). In the case of IPI, the high risk group exhibited higher RI_max than the low risk group (p = 0.004). In the case of revised IPI, the RI_max of the low risk group were significantly lower than the intermediate and high risk groups, respectively (p < 0.01). The MVDIs of the best outcome group were decreased in comparison to the moderate outcome group (p = 0.029). There was a significant negative correlative relationship between RI_max and MVDI, and the inclinations for decreased MVDIs were slightly associated with increased RIs.

Conclusions

RI_max extracted from DTPFP had a significant relationship to extranodal involvement, staging, IPI, and revised IPI. MVDI showed significant negative correlation with RI_max. Further large scale studies are warranted to support and extend these preliminary results.

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