Reproducibility of planar 123I-meta-iodobenzylguanidine (MIBG) myocardial scintigraphy in patients with heart failure

Caroline E Veltman,Ernst E Van Der Wall,Jeroen J Bax,Imad Al Younis,Arthur J H A Scholte,Mark J Boogers,Joris E Meinardi,Petra Dibbets-Schneider

doi:10.1007/s00259-012-2180-2

Abstract

PurposeDespite its high prognostic value, widespread clinical implementation of 123I-meta-iodobenzylguanidine (MIBG) myocardial scintigraphy is hampered by a lack of validation and standardization. The purpose of this study was to assess the reliability of planar 123I-MIBG myocardial scintigraphy in patients with heart failure (HF).MethodsPlanar myocardial MIBG images of 70 HF patients were analysed by two experienced and one inexperienced observer. The reproducibility of early and delayed heart-to-mediastinum (H/M) ratios, as well as washout rate (WR) calculated by two different methods, was assessed using the intraclass correlation coefficient (ICC) and the Bland-Altman analysis. In addition, a subanalysis in patients with a very low H/M ratio (delayed H/M ratio <1.4) was performed. The delayed H/M ratio was also assessed using fixed-size oval and circular cardiac regions of interest (ROI).ResultsIntra- and interobserver analyses and experienced versus inexperienced observer analysis showed excellent agreement for the measured early and delayed H/M ratios and WR on planar 123I-MIBG images (the ICCs for the delayed H/M ratios were 0.98, 0.96 and 0.90, respectively). In addition, the WR without background correction resulted in higher reliability than the WR with background correction (the interobserver Bland-Altman 95 % limits of agreement were −2.50 to 2.16 and −10.10 to 10.14, respectively). Furthermore, the delayed H/M ratio measurements remained reliable in a subgroup of patients with a very low delayed H/M ratio (ICC 0.93 for the inter-observer analysis). Moreover, a fixed-size cardiac ROI could be used for the assessment of delayed H/M ratios, with good reliability of the measurement.ConclusionThe present study showed a high reliability of planar 123I-MIBG myocardial scintigraphy in HF patients, confirming that MIBG myocardial scintigraphy can be implemented easily for clinical risk stratification in HF.

Highlights

The ageing of the population and the improved medical treatment of cardiac patients has led to an increased prevalence of heart failure (HF) [1]
We evaluated the influence of two different methods to assess the washout ratio (WR), the effect of cardiac regions of interest (ROI) size and position on the assessment of the H/M ratio, as well as the impact of the level of postprocessing experience on the reproducibility of planar MIBG images
The study population consisted of New York Heart Association (NYHA) functional class III/IV HF patients with an impaired left ventricle ejection fraction (LVEF) of ≤35 % who were clinically referred for MIBG myocardial scintigraphy

Summary

Introduction

The ageing of the population and the improved medical treatment of cardiac patients has led to an increased prevalence of heart failure (HF) [1]. Increased myocardial sympathetic activity is a prominent feature of HF by which the failing heart tries to compensate for the reduced cardiac output [3]. The increased sympathetic activity causes increased neuronal release of norepinephrine (NE), that leads to a significant reduction in presynaptic NE uptake due to posttranscriptional downregulation of the cardiac NE transporter [5]. MIBG is taken up into the presynaptic cardiac sympathetic nerves by the NE uptake-1 transporter, and the amount of MIBG retention over several hours after administration reflects neuronal integrity [7]. The most commonly used quantitative measurements of myocardial MIBG uptake are the calculated heart-to-mediastinum (H/M) ratio and washout ratio (WR) determined from planar MIBG images. Planar MIBG myocardial scintigraphy has been demonstrated to have strong prognostic value [13, 14]

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