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Open Access Highly Accessed Original research

When is reacquisition necessary due to high extra-cardiac uptake in myocardial perfusion scintigraphy?

Allan Johansen1, Milan Lomsky2, Oke Gerke13, Lars Edenbrandt245, Lena Johansson2, Gunhild Hansen1, Birgitte Jensen1, Maria Sallerup Reid2, Lise-Lott Johansson4, Camilla Olofsson4, David Minarik4, Karin Nyström5, Per Wollmer4 and Elin Trägårdh4*

Author Affiliations

1 Department of Nuclear Medicine, Odense University Hospital, Odense, Denmark

2 Department of Molecular and Clinical Medicine, Clinical Physiology, Sahlgrenska University Hospital, Gothenburg, Sweden

3 Centre of Health Economics Research, Department of Business and Economics, University of Southern Denmark, Odense, Denmark

4 Nuclear Medicine Unit, Skåne University Hospital, Lund University, Malmo, Sweden

5 EXINI Diagnostics AB, Lund, Sweden

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EJNMMI Research 2013, 3:20  doi:10.1186/2191-219X-3-20

Published: 25 March 2013

Abstract

Background

Technetium-labeled agents, which are most often used for assessing myocardial perfusion in myocardial perfusion scintigraphy (MPS), are cleared by the liver and excreted by the biliary system. Spillover from extra-cardiac activity into the myocardium, especially the inferior wall, might conceal defects and lower the diagnostic accuracy of the study. The objective was to determine rules of thumb for when reacquisition is useful due to high extra-cardiac uptake, i.e., when interpretation of the studies was affected by poor image quality.

Methods

Patients admitted to MPS at any of the three study sites, who also underwent a reacquisition due to high extra-cardiac uptake were included. Image quality was assessed by ten technologists on a scale ranging from 1 to 5. Interpretations regarding the presence/absence of ischemia/infarction, including the certainty of the diagnosis, were made by three physicians.

Results

There was a statistically significant increase in image quality between the first and the repeated acquisition (1,256 cases of increased quality at the repeated study (66%), 134 cases of decreased quality at the repeated study (7%), 510 cases of unchanged quality (27%) P < 0.0001). The number of equivocal studies, interpreted by physicians, decreased when evaluating the repeated studies compared to the first studies for all physicians, both for the interpretations of ischemia and for infarction. Receiver operating characteristic analyses revealed that for both endpoints (ischemia, infarction) and all physicians, the optimal cutoff point for performing a reacquisition was between quality categories 2 and 3.

Conclusion

This study indicates that repeat acquisition is useful when (1) the intensity of the extra-cardiac uptake is equal to or higher than the cardiac uptake when there is no separation between the extra-cardiac uptake and the inferior cardiac wall and (2) when the intensity of the extra-cardiac uptake is higher than the cardiac uptake when there is a separation between the extra-cardiac uptake and the inferior wall of less than one cardiac wall.

Keywords:
Myocardial perfusion imaging; Quality assessment; Image interpretation; Extra-cardiac uptake; Ischemic heart disease