Absolute Quantification of Myocardial Blood Flow with 13N-Ammonia and 3-Dimensional PET

Abstract

The aim of this study was to compare 2-dimensional (2D) and 3-dimensional (3D) dynamic PET for the absolute quantification of myocardial blood flow (MBF) with 13 N-ammonia ( 13 N-NH 3 ). Methods: 2D and 3D MBF measurements were collected from 21 patients undergoing cardiac evaluation at rest (n 5 14) and during standard adenosine stress (n 5 7). A lutetium yttrium oxyorthosilicate-based PET/CT system with retractable septa, enabling the sequential acquisition of 2D and 3D images within the same patient and study, was used. All 2D studies were performed by injecting 700-900 MBq of 13 N-NH 3 . For 14 patients, 3D studies were performed with the same injected 13 N-NH 3 dose as that used in 2D studies. For the remaining 7 patients, 3D images were acquired with a lower dose of 13 N-NH 3 , that is, 500 MBq. 2D images reconstructed by use of filtered backprojection (FBP) provided the reference standard for MBF measurements. 3D images were reconstructed by use of Fourier rebinning (FORE) with FBP (FORE-FBP), FORE with orderedsubsets expectation maximization (FORE-OSEM), and a reprojection algorithm (RP). Results: Global MBF measurements derived from 3D PET with FORE-FBP (r 5 0.97), FORE-OSEM (r 5 0.97), and RP (r 5 0.97) were well correlated with those derived from 2D FBP (all Ps , 0.0001). The mean 6 SD differences in global MBF measurements between 3D FORE-FBP and 2D FBP and between 3D FORE-OSEM and 2D FBP were 0.01 6 0.14 and 0.01 6 0.15 mL/min/g, respectively. The mean 6 SD difference in global MBF measurements between 3D RP and 2D FBP was 0.00 6 0.16 mL/min/g. The best correlation between 2D PET and 3D PET performed with the lower injected activity was found for the 3D FORE-FBP reconstruction algorithm (r 5 0.95, P , 0.001). Conclusion: For this scanner type, quantitative measurements of MBF with 3D PET and 13 N-NH 3 were in excellent agreement with those obtained with the 2D technique, even when a lower activity was injected. The assessment of quantitative regional myocardial blood flow (MBF) and coronary flow reserve with 13 Nammonia ( 13 N-NH 3 ) has been well established for 2-dimensional (2D) PET (1-4). Recently, there has been growing interest in the use of PET and PET/CT scanners that operate only in the 3-dimensional (3D) mode (5). The main advantage of the 3D mode (with septa retracted) of data acquisition is that its sensitivity is higher than that of the conventional 2D mode (septa extended) (6,7). The increased counting rate in the 3D acquisition mode, however, comes at the cost of increased scatter, number of random events, and dead time compared with those observed in the 2D mode (8). Although the use of 3D PET has demonstrated significant advantages over the use of 2D PET for brain imaging (9-11), the relative benefits of 3D PET for whole-body oncology (12) and cardiac applications are less clear. Previous experimental animal and clinical comparisons of 2D and 3D PET performance for myocardial perfusion imaging with 13 N-NH 3 , 15 O-H 2 O, and 82 Rb showed either a disadvantage for 3D PET (13) or ima...

Coronary calcium score scans for attenuation correction of quantitative PET/CT 13N-ammonia myocardial perfusion imaging

“…This has clinical implications, because CCS has been established as valuable diagnostic indicator and highly prognostic predictor of cardiovascular events [21]. Recently, CCS has emerged as an important adjunct to SPECT [4] or PET [22] MPI providing diagnostic and prognostic information. In particular, in patients with normal perfusion, some authors have found an added value of high calcium score to discriminate between low and high event rate [22], or to identify CAD [23].…”

“…However, as this would equally apply to both methods of AC it may not have affected the comparability and interchange ability of both methods. Furthermore, we performed the CCS scan in inspiration following the generally accepted recommendations, although it has been previously reported, that CCS in full expiration may be more accurate for correction in the apical myocardium [4]. However, the latter has been reported for SPECT but not for PET scans.…”

“…First, a CT scout scan was used to localize the field of view for the following CT and emission scans. Transmission data for CT AC were acquired in a non-gated low dose CT scan, using the following parameters: scan length 15 cm, 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 5 started in parallel and consisted of nine 10 sec, six 15 sec, three 20 sec, two 30 sec, and one 120 sec frames as previously reported [4]. PET data was reconstructed 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 7…”

“…if appropriate tracers [1][2][3][4][5] and adequate attenuation correction (AC) is used. CT images can be transformed into PET attenuation coefficients which allow correction for myocardial perfusion quantification using a hybrid PET/CT scanner [6,7].…”

Synthese von 11C‐, 18F‐, 15O‐ und 13N‐Radiotracern für die Positronenemissionstomographie

“…13 N]Ammoniak zur Messung des myokardialen Blutstroms [291][292][293][294] und die Einführung von 13 N in Aminosäuren durch enzymatische Synthese. [295][296][297][298][299][300] …”