QUANTITATIVE APPROACH TO ASSIST NEUROBLASTOMA ASSESSMENT BY MEASURING I-123 mIBG UPTAKE IN SCINTIGRAPHIC IMAGES

Abstract

Whole-body 123 I-Metaiodobenzylguanidine (mIBG) scintigraphy is used as the primary image modality in neuroblastoma detection. It is the most sensitive and specific method for staging and response evaluation. Validated semi-quantitative scoring methods with low interobserver variability and high reproducibility have shown to be indispensable for the evaluation of response to therapy. However, low resolution, noise and acquisition difficulties, specially in children, make low definition scans. These facts increase observer dependent interpretations that limit assessment and complicate to put a scoring method succesfully into practice. It is essential to have an objective and reliable measure of response to test the activity of therapies. In this paper we propose the use of a quantitative observer-independent measurement of the strength of uptake to be used as an additional tool for assisting the International Society of Paediatric Oncology Europe Neuroblastoma Group (SIOPEN) semi-quantitative scoring method. This is the scoring method recommended by the SIOPEN Nuclear Medicine and Physics Committee, in collaborative work with the Children's Oncology Group, as the standard one for acquiring and reporting diagnostic paediatric mIBG scans across Europe. Our proposed method is based on the ratio between the amount of specific uptake at tumours and the amount of non-specific uptake at SIOPEN anatomical sectors which has shown to be constant in all the scans of the patients.

Recognition of Abnormal Uptake through 123I-mIBG Scintigraphy Entropy for Paediatric Neuroblastoma Identification

“…At limb sectors we set ρ k = 3 and C k = 3 and we did not search inside if R k < 1 in Equation (7). Results are shown in Table 2, and a summary of the procedure in Table 3.…”

“…Those bone parts with metastases become visible and, at worst, only the skeleton is visible while soft tissue presents low uptake or it is not visible at all due to neuroblastoma tissue consuming all the 123 I-mIBG (Figure 1c) [7].…”

“…The proposed method performs a preprocessing of the image, extracting numeric values, which highlights the zones with a high probability of containing a tumour or metastasis [6]. Furthermore, these measurements are considered as its entropy, and allow following the evolution of the patient over time [7]. The quantitative measurement adds more descriptive information on tumours, which may be included in models of nonlinear dynamics of cancer recurrence to study the correlation between uptake and tumour relapse.…”