A European myocardial 123I-mIBG cross-calibration phantom study

Abstract

AimPlanar myocardial 123I-meta-iodobenzylguanidine (123I-mIBG) scintigraphy is a highly reproducible technique. However, differences in collimator use are one of the most important factors that cause variation among institutions and studies in heart-to-mediastinum (H/M) ratio. Therefore, standardization among various gamma camera-collimator combinations is needed. Previously, a phantom has been developed to cross-calibrate different acquisition conditions in Japan. For further cross-calibration of European myocardial 123I-mIBG imaging, the aim of this study was to collect 123I-mIBG data for H/M ratios from common European gamma camera vendors.Methods210 experiments were performed in 27 European institutions. Based on these experiments, conversion coefficients for each gamma camera-collimator combination were calculated. An averaged conversion coefficient of 0.88 was used to calculate a standardized H/M ratio.ResultsOn average, LE-collimator-derived H/M ratios were significantly lower compared to ME-collimator-derived H/M ratios. The mean conversion coefficients ranged from 0.553 to 0.605 for the LE-collimator group and from 0.824 to 0.895 for the ME-collimator group.ConclusionClinically established H/M ratios can be converted into standardized H/M ratios using cross-calibrated conversion coefficients. This standardization is important for identifying appropriate thresholds for adequate risk stratification. In addition, this cross-calibration enables comparison between different national and international data.

123I-mIBG and the phantom tollbooth

“…The results of Verschure et al 9 support the concept that cross-calibration myocardial 123 I-mIBG phantom studies allow for conversion of different institutional H/ M ratios to standardized H/M ratios, which may facilitate multicenter comparison of myocardial 123 I-mIBG results. The method can be easily applied reducing variation in outcome measures and thereby further strengthening the clinical role of myocardial 123 I-mIBG scintigraphy.…”

“…Therefore, the results obtained in Japan could not automatically be extrapolated to other countries and respective institutions. In this issue of the Journal, Verschure et al 9 have performed a similar cross-calibration myocardial 123 I-mIBG phantom study to calculate conversion coefficients for specific individual gamma camera-collimator combinations in 27 European centers: one from Austria, seven from Belgium, 18 from the Netherlands, and one from the United Kingdom. Two hundred and ten phantom studies were performed using three different gamma camera brands (n 1 = 148, n 2 = 44 and n 3 = 18).…”

“…As the authors used a slightly modified version of the original Japanese phantom (lighter weight due to some hollow in acrylic parts filled with nonradioactive water), minor differences in reference values were adjusted to obtain matching results with the Figure 1. Schematic representation of septal penetration of 123 I emission using medium-energy and low-energy collimators (upper row), with corresponding planar images acquired with a Jaszczak phantom (middle row) and the phantom used by Verschure et al 9 (lower row). Image quality is better for the medium-energy collimator because of higher contrast and lower noise.…”

“…These comparisons could even be performed retrospectively applying the appropriate corrections to the already existing multicenter data. Thus, as in Norton Juster's children's book The phantom tollbooth, in which a bored, lonely boy is startled by the unexpected arrival of a large, gift-wrapped package containing a tollbooth, which turns out to be a gateway into a magical parallel universe of the enchanted Kingdom of Wisdom in the Lands Beyond, the cross-calibration phantom study of Verschure et al 9 may represent the gateway for largescale clinical implementation of cardiac 123 I-mIBG scintigraphy. This study extends the Japanese phantom experience to European institutions enabling conversion coefficients for H/M ratio within Europe, which may help myocardial 123 I-mIBG scintigraphy to obtain more extensive data and enhance the evidence to support its routine clinical application.…”

Phase dyssynchrony and 123I-meta-iodobenzylguanidine innervation imaging towards standardization

“…4 However, the recent development of a calibration phantom-based standardization method provides optimal conversion coefficients for most of the Anger-type camera-collimator combinations. 5,6 The standardization method could be applied to cadmium-zinc-telluride (CZT) cameras, either by empirical conversion equation between two systems with a phantom study 7,8 or calibration phantom experiments as described for Anger cameras. 9 On the other hand, the assessment of regional 123 ImIBG uptake with SPECT has not been standardized so rigorously yet.…”