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Logo of bmcmiBioMed Centralsearchsubmit a manuscriptregisterthis articleBMC Medical Imaging
 
BMC Med Imaging. 2012; 12: 5.
Published online Mar 29, 2012. doi:  10.1186/1471-2342-12-5
PMCID: PMC3368747
Standardized volumetric 3D-analysis of SPECT/CT imaging in orthopaedics: overcoming the limitations of qualitative 2D analysis
Michael T Hirschmann,corresponding author1 Christopher R Wagner,2 Helmut Rasch,3 and Johann Henckel4
1Department of Orthopaedic Surgery and Traumatology, Kantonsspital Bruderholz, CH-4101 Bruderholz, Switzerland
2OrthoImagingSolutions Ltd., London, UK
3Institute for Radiology and Nuclear Medicine, Kantonsspital Bruderholz, CH-4101 Bruderholz, Switzerland
4Department of Musculoskeletal Surgery, Imperial College, London, UK
corresponding authorCorresponding author.
Michael T Hirschmann: michael.hirschmann/at/unibas.ch; Christopher R Wagner: Chris/at/orthoimagingsolutions.com; Helmut Rasch: helmut.rasch/at/ksbh.ch; Johann Henckel: j.henckel/at/imperial.ac.uk
Received February 11, 2011; Accepted March 29, 2012.
Abstract
Background
SPECT/CT combines high resolution anatomical 3D computerized tomography (CT) and single photon emission computerized tomography (SPECT) as functional imaging, which provides 3D information about biological processes into a single imaging modality. The clinical utility of SPECT/CT imaging has been recognized in a variety of medical fields and most recently in orthopaedics; however, clinical adoption has been limited due to shortcomings of analytical tools available. Specifically, SPECT analyses are mainly qualitative due to variation in overall metabolic uptake among patients. Furthermore, most analyses are done in 2D, although rich 3D data are available. Consequently, it is difficult to quantitatively compare the position, size, and intensity of SPECT uptake regions among patients, and therefore difficult to draw meaningful clinical conclusions.
Methods
We propose a method for normalizing orthopaedic SPECT/CT data that enables standardised 3D volumetric quantitative measurements and comparison among patients. Our method is based on 3D localisation using clinically relevant anatomical landmarks and frames of reference, along with intensity value normalisation using clinically relevant reference regions. Using the normalised data, we describe a thresholding technique to distinguish clinically relevant hot spots from background activity.
Results
Using an exemplar comparison of two patients, we demonstrate how the normalised, 3D-rendered data can provide a richer source of clinical information and allow quantitative comparison of SPECT/CT measurements across patients. Specifically, we demonstrate how non-normalized SPECT/CT analysis can lead to different clinical conclusions than the normalized SPECT/CT analysis, and that normalized quantitative analysis can be a more accurate indicator of pathology.
Conclusions
Conventional orthopaedic frames of reference, 3D volumetric data analysis and thresholding are used to distinguish clinically relevant hot spots from background activity. Our goal is to facilitate a standardised approach to quantitative data collection and comparison of clinical studies using SPECT/CT, enabling more widespread clinical use of this powerful imaging tool.
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