DOI: 10.1186/s40658-017-0175-6Pages: 1-16

[123I]FP-CIT ENC-DAT normal database: the impact of the reconstruction and quantification methods

1. University Hospital Southampton NHS Foundation Trust, Department of Medical Physics

2. University College London Hospital NHS Foundation Trust, Institute of Nuclear Medicine

3. University of Szeged, Department of Nuclear Medicine and Euromedic Szeged

4. University of Amsterdam, Department of Nuclear Medicine, Academic Medical Center

5. Medical University of Vienna, Department of Nuclear Medicine

6. Az. Ospedaliera Universitaria San Martino, Medical Physics Unit

7. Université Catholique de Louvain, Nuclear Medicine Division, Mont-Godinne Medical Center

8. Karolinska University Hospital, Department of Nuclear Medicine, Medical Physics

9. Copenhagen University Hospital, Rigshospitalet, Neurobiology Research Unit and Department of Clinical Physiology, Nuclear Medicine and PET

10. University of Leipzig, Department of Nuclear Medicine

11. University of Nice-Sophia Antipolis, Nuclear Medicine Department, Centre Antoine Lacassagne

12. Gazi University, Department of Nuclear Medicine, Faculty of Medicine

13. University Hospital and K.U. Leuven, Nuclear Medicine

14. Municipal Hospital of Karlsruhe Inc., Department of Nuclear Medicine

15. Karolinska Institutet, Department of Clinical Neuroscience, Center for Psychiatric Research

Correspondence to:
Livia Tossici-Bolt
Tel: +44 0238120 5483
Email: livia.bolt@uhs.nhs.uk

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Abstract

Background

[123I]FP-CIT is a well-established radiotracer for the diagnosis of dopaminergic degenerative disorders. The European Normal Control Database of DaTSCAN (ENC-DAT) of healthy controls has provided age and gender-specific reference values for the [123I]FP-CIT specific binding ratio (SBR) under optimised protocols for image acquisition and processing. Simpler reconstruction methods, however, are in use in many hospitals, often without implementation of attenuation and scatter corrections. This study investigates the impact on the reference values of simpler approaches using two quantifications methods, BRASS and Southampton, and explores the performance of the striatal phantom calibration in their harmonisation.

Results

BRASS and Southampton databases comprising 123 ENC-DAT subjects, from gamma cameras with parallel collimators, were reconstructed using filtered back projection (FBP) and iterative reconstruction OSEM without corrections (IRNC) and compared against the recommended OSEM with corrections for attenuation and scatter and septal penetration (ACSC), before and after applying phantom calibration. Differences between databases were quantified using the percentage difference of their SBR in the dopamine transporter-rich striatum, with their significance determined by the paired t test with Bonferroni correction.

Attenuation and scatter losses, measured from the percentage difference between IRNC and ACSC databases, were of the order of 47% for both BRASS and Southampton quantifications. Phantom corrections were able to recover most of these losses, but the SBRs remained significantly lower than the “true” values (p < 0.001). Calibration provided, in fact, “first order” camera-dependent corrections, but could not include “second order” subject-dependent effects, such as septal penetration from extra-cranial activity. As for the ACSC databases, phantom calibration was instrumental in compensating for partial volume losses in BRASS (~67%, p < 0.001), while for the Southampton method, inherently free from them, it brought no significant changes and solely corrected for residual inter-camera variability (−0.2%, p = 0.44).

Conclusions

The ENC-DAT reference values are significantly dependent on the reconstruction and quantification methods and phantom calibration, while reducing the major part of their differences, is unable to fully harmonize them. Clinical use of any normal database, therefore, requires consistency with the processing methodology. Caution must be exercised when comparing data from different centres, recognising that the SBR may represent an “index” rather than a “true” value.

This article is freely available, click here to access the full text/PDF

  • Accepted: Jan 17, 2017
  • Online: Jan 28, 2017

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