Improved resolution of bone scintigraphy by using an iterative deconvolution technique (IDT): Effects on visualization and interpretation of focal lesions

Abstract

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Objectives: Deconvolution of planar scintigrams can improve image quality with respect to contrast and resolution. We used an MLEM based iterative deconvolution technique which was developed and implemented in our department. Aim of this study was to analyze whether IDT allows for improved visualization and interpretation of focal lesions on whole body bone scans (WBS). Methods: 77 WBS (49 because of oncological, 28 because of rheumatological diseases) were included into the study. Conventional images and images processed with IDT were re-analyzed separately with regard to visualization (v-score (VS): on a 0 to 5 scale, 0 being not visible) and interpretation (i-score (IS): 0 to 2 scale, 0 being unclear) of bone lesions. Lesions were classified into 5 different types (defects, focally increased uptake of small, moderate and large size, diffuse uptake) and grouped according to their anatomical localisation (skull, vertebral column, ribs and sternum, pelvis, peripheral skeleton: articular or non-articular lesions). For each type of lesions we evaluated whether IDT improves VS and/or IS, or if it changes the clinical diagnosis (benign vs. malignant). Results: 365 lesions were identified. IDT improved the VS for 212/365 (55%) lesions, in 124 (34%) for more than one point. IS was improved for 211/365 (55%) lesions. Both VS and IS were particularly improved for small lesions (VS: 88.1% / IS: 82.1%), focal lesions (VS: 70.1% / IS: 69.5%), large lesions (VS: 51% / IS: 53.7%) and for the following localizations: vertebral column (VS: 65.4% / IS: 61.5%), articular peripheral skeleton (VS: 63.7% / IS: 67.2%), and pelvis (VS: 64.3% / IS: 62%). Improvement of VS/IS of at least 40% was observed for most of the other types and localisation as well except for diffuse lesions (VS: 17%, IS: 16%). 58 new lesions in 23 patients (12 of them obese) were detected in scans reprocessed by IDT. Clinical diagnosis was changed in 7/77 patients. Conclusions: IDT improves image quality of conventional bone scans, in particular visualization and interpretation of small focal lesions in obese patients.