Standardized volumetric 3D-analysis of SPECT/CT imaging in orthopaedics: overcoming the limitations of qualitative 2D analysis

<p>Abstract</p> <p>Background</p> <p>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.</p> <p>Methods</p> <p>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.</p> <p>Results</p> <p>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.</p> <p>Conclusions</p> <p>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.</p

Normal values for nuclear cardiology: Japanese databases for myocardial perfusion, fatty acid and sympathetic imaging and left ventricular function

Myocardial normal databases for stress myocardial perfusion study have been created by the Japanese Society of Nuclear Medicine Working Group. The databases comprised gender-, camera rotation range- and radiopharmaceutical-specific data-sets from multiple institutions, and normal database files were created for installation in common nuclear cardiology software. Based on the electrocardiography-gated single-photon emission computed tomography (SPECT), left ventricular function, including ventricular volumes, systolic and diastolic functions and systolic wall thickening were also analyzed. Normal databases for fatty acid imaging using 123I-beta-methyl-iodophenyl-pentadecanoic acid and sympathetic imaging using 123I-meta-iodobenzylguanidine were also examined. This review provides lists and overviews of normal values for myocardial SPECT and ventricular function in a Japanese population. The population-specific approach is a key factor for proper diagnostic and prognostic evaluation

Coronary artery calcium progression after coronary artery bypass grafting surgery

Objectives Accelerated atherosclerosis is a well-established phenomenon after coronary artery bypass grafting surgery (CABG). In this study, we analysed coronary artery calcium (CCS) progression after CABG.Methods We retrospectively measured the CCS Agatston score (AS), volume score (VS) and mass score (MS) of 39 patients before and after CABG. The annualised CCS change and annualised CCS percent change of each coronary artery, coronary artery segments proximal and distal to anastomosis were analysed.Results Mean age at the time of the surgery was 59.8±8.5 years. Follow-up period between the first and second CT scans was 6.7±2.8 (range, 1.1–12.8) years. Annualised CCS percent change (AS, VS and MS) of the coronary segments proximal-to-anastomosis did not differ from that of the non-grafted coronary arteries as follow: segments proximal-to-anastomosis: median (Q1–Q3) 12.8 (5.0–37.4), 13.7 (6.1–41.1) and 14.9 (5.4–53.7), left main coronary artery 12.6 (7.4–43.8), 22.0 (8.1–44.4) and 18.2 (7.3–57.4), non-grafted left circumflex artery: 13.5 (4.4–38.1), 10.5 (2.9–45.2) and 11.5 (7.1–47.9) and non-grafted right coronary artery: 31.4 (14.4–74.5), 25.2 (16.7–62.0) and 31.3 (23.8–85.6), respectively. Likewise, annualised percent change (AS, VS and MS) was similar between the native coronary arteries. Multivariate regression analysis showed that diabetes mellitus was the only predictor of annualised percent progression of the total CCS of &gt;15% (HR, 8.12; 95% CI, 1.05 to 26.6; p=0.04).Conclusion The CCS post-CABG did not follow an accelerated progression process. Among coronary artery disease risk factors, diabetes mellitus is the only predictor of annualised CCS percent progression of &gt;15% post-CABG