Optimized dose regimen for whole-body FDG-PET imaging

Eleonore H de Groot, Nieky Post, Ronald Boellaard, Nils Rl Wagenaar, Antoon Tm Willemsen, Jorn A van Dalen, Eleonore H de Groot, Nieky Post, Ronald Boellaard, Nils Rl Wagenaar, Antoon Tm Willemsen, Jorn A van Dalen

Abstract

Background: The European Association of Nuclear Medicine procedure guidelines for whole-body fluorodeoxyglucose positron-emission tomography (FDG-PET) scanning prescribe a dose proportional to the patient's body mass. However, clinical practice shows degraded image quality in obese patients indicating that using an FDG dose proportional to body mass does not overcome size-related degradation of the image quality. The aim of this study was to optimize the administered FDG dose as a function of the patient's body mass or a different patient-dependent parameter, providing whole-body FDG-PET images of a more constant quality.

Methods: Using a linear relation between administered dose and body mass, FDG-PET imaging was performed on two PET/computed tomography scanners (Biograph TruePoint and Biograph mCT, Siemens). Image quality was assessed by the signal-to-noise ratio (SNR) in the liver in 102 patients with a body mass of 46 to 130 kg. Moreover, the best correlating patient-dependent parameter was derived, and an optimized FDG dose regimen was determined. This optimized dose regimen was validated on the Biograph TruePoint system in 42 new patients. Furthermore, this relation was verified by a simulation study, in which patients with different body masses were simulated with cylindrical phantoms.

Results: As expected, both PET systems showed a significant decrease in SNR with increasing patient's body mass when using a linear dosage. When image quality was fitted to the patient-dependent parameters, the fit with the patient's body mass had the highest R2. The optimized dose regimen was found to be Anew= c/t × m2, where m is the body mass, t is the acquisition time per bed position and c is a constant (depending on scanner type). Using this relation, SNR no longer varied with the patient's body mass. This quadratic relation between dose and body mass was confirmed by the simulation study.

Conclusion: A quadratic relation between FDG dose and the patient's body mass is recommended. Both simulations and clinical observations confirm that image quality remains constant across patients when this quadratic dose regimen is used.

Figures

Figure 1
Figure 1
Axial slice with ROI. An axial slice of one of the patient scans showing the ROI used to derive the SNR in the liver (red contour).
Figure 2
Figure 2
SNRL and SNRL/(t1/2) versus body mass. Signal-to-noise ratio in the liver (SNRL) versus body mass (left) and SNRL normalized to an acquisition time per bed position of 1 min versus body mass (right) for the Biograph TruePoint (TP), OSEM3D reconstruction (A, B) and the Biograph mCT for three different reconstructions: (C, D) OSEM3D, (E, F) OSEM3D + PSF, and (G, H) OSEM3D + PSF + TOF. The lines in the graphs are the result of linear regression of the data.
Figure 3
Figure 3
Patient scans in the old and new dose regimens. Coronal and transverse slices of a whole-body FDG-PET scan for (A) a patient of 70 kg (dose = 149 MBq) and (B) a patient of 95 kg (dose = 217 MBq), using the old dose regimen, and for (C) a patient of 70 kg (dose = 138 MBq) and (D) a patient of 95 kg (dose = 257 MBq), using a quadratic relation between body mass and FDG dose. Using the old relation between body mass and dose, the dose would have been (C) 149 and (D) 217 MBq, respectively. All four scans were performed on the Biograph TruePoint. The location of the transverse slice is indicated on the coronal view.
Figure 4
Figure 4
SNRnorm versus body mass. Signal-to-noise ratio normalized for the administered FDG dose and scan time per bed position (SNRnorm) versus body mass. Besides the best fits through the data, also their 95% confidence intervals are shown, and the best fit with the value of the parameter d fixed to 1 for (A) the Biograph TruePoint (TP) and for the Biograph mCT for three different reconstructions: (B) OSEM3D, (C) OSEM3D + PSF and (D) OSEM3D + PSF + TOF. The fit with the parameter d fixed to 1 corresponds to the situation where SNRL can be kept constant by a quadratic relation between dose and body mass.
Figure 5
Figure 5
Comparison between the old and new dose regimens. SNRL versus body mass for the old and new dose regimens for the Biograph TruePoint.
Figure 6
Figure 6
Axial slices of the simulated mathematical phantom. Representative axial slices of the simulated mathematical phantom with various diameters. Images were taken from the simulation applying a linear relationship between weight and administered activity. The region of interest to derive SNR is indicated by the red contour.
Figure 7
Figure 7
Simulation results. SNR versus the body mass represented by the phantom for constant, linear and quadratic dose regimes using AW-OSEM reconstruction. The error bars represent two standard deviations.

References

    1. Boellaard R, O’Doherty MJ, Weber WA, Mottaghy FM, Lonsdale MN, Stroobants SG, Oyen WJG, Kotzerke J, Hoekstra OS, Pruim J, Marsden PK, Tatsch K, Hoekstra CJ, Visser EP, Arends B, Verzijlbergen FJ, Zijlstra JM, Comans EFI, Lammertsma AA, Paans AM, Willemsen AT, Beyer T, Bockisch A, Schaefer-Prokop C, Delbeke D, Baum RP, Chiti A, Krause BJ. FDG PET and PET/CT: EANM procedure guidelines for tumour PET imaging: version 1.0. Eur J Nucl Med Mol Imaging. 2010;3(1):181–200. doi: 10.1007/s00259-009-1297-4.
    1. Boellaard R, Oyen WJG, Hoekstra CJ, Hoekstra OS, Visser EP, Willemsen AT, Arends B, Verzijlbergen FJ, Zijlstra J, Paans AM, Comans EFI, Pruim J. The Netherlands protocol for standardisation and quantification of FDG whole body PET studies in multi-centre trials. Eur J Nucl Med Mol Imaging. 2008;3(12):2320–2333. doi: 10.1007/s00259-008-0874-2.
    1. Matsumoto K, Matsuura H, Minota E, Sakamoto S, Nakamoto Y, Senda M. Evaluation of optimized injection dose and acquisition time using body mass index for three-dimensional whole-body FDG-PET. Nihon Hoshasen Gijutsu Gakkai Zasshi. 2004;3(11):1564–1573.
    1. Watson CC, Casey ME, Bendriem B, Carney JP, Townsend DW, Eberl S, Meikle S, Difilippo FP. Optimizing injected dose in clinical PET by accurately modeling the counting-rate response functions specific to individual patient scans. J Nucl Med. 2005;3(11):1825–1834.
    1. Everaert H, Vanhove C, Lahoutte T, Muylle K, Caveliers V, Bossuyt A, Franken PR. Optimal dose of 18F-FDG required for whole-body PET using an LSO PET camera. Eur J Nucl Med Mol Imaging. 2003;3(12):1615–1619. doi: 10.1007/s00259-003-1317-8.
    1. Halpern BS, Dahlbom M, Auerbach MA, Schiepers C, Fueger BJ, Weber WA, Silverman DHS, Ratib O, Czernin J. Optimizing imaging protocols for overweight and obese patients: a lutetium orthosilicate PET/CT study. J Nucl Med. 2005;3(4):603–607.
    1. Halpern BS, Dahlbom M, Quon A, Schiepers C, Waldherr C, Silverman DH, Ratib O, Czernin J. Impact of patient weight and emission scan duration on PET/CT image quality and lesion detectability. J Nucl Med. 2004;3(5):797–801.
    1. Masuda Y, Kondo C, Matsuo Y, Uetani M, Kusakabe K. Comparison of imaging protocols for 18F-FDG PET/CT in overweight patients: optimizing scan duration versus administered dose. J Nucl Med. 2009;3(6):844–848. doi: 10.2967/jnumed.108.060590.
    1. Accorsi R, Karp JS, Surti S. Improved dose regimen in pediatric PET. J Nucl Med. 2010;3(2):293–300. doi: 10.2967/jnumed.109.066332.
    1. Conti M. State of the art and challenges of time-of-flight PET. Phys Med. 2009;3(1):1–11. doi: 10.1016/j.ejmp.2008.10.001.
    1. Conti M. Focus on time-of-flight PET: the benefits of improved time resolution. Eur J Nucl Med Mol Imaging. 2011;3(6):1147–1157. doi: 10.1007/s00259-010-1711-y.
    1. El Fakhri G, Surti S, Trott CM, Scheuermann J, Karp JS. Improvement in lesion detection with whole-body oncologic time-of-flight PET. J Nucl Med. 2011;3(3):347–353. doi: 10.2967/jnumed.110.080382.
    1. Panin VY, Kehren F, Michel C, Casey M. Fully 3-D PET reconstruction with system matrix derived from point source measurements. IEEE Trans Med Imaging. 2006;3(7):907–921.
    1. Hume R. Prediction of lean body mass from height and weight. J Clin Pathol. 1966;3(July):389–392.
    1. Hallynck TH, Soep HH, Thomis JA, Boelaert J, Daneels R, Dettli L. Should clearance be normalised to body surface or to lean body mass? Br J Clin Pharmacol. 1981;3:523–526. doi: 10.1111/j.1365-2125.1981.tb01163.x.
    1. Graham MM, Badawi RD, Wahl RL. Variations in PET/CT methodology for oncologic imaging at U.S. academic medical centers: an imaging response assessment team survey. J Nucl Med. 2011;3(2):311–317. doi: 10.2967/jnumed.109.074104.
    1. Beyer T, Czernin J, Freudenberg LS. Variations in clinical PET/CT operations: results of an international survey of active PET/CT users. J Nucl Med. 2011;3(2):303–310. doi: 10.2967/jnumed.110.079624.
    1. Stauss J, Franzius C, Pfluger T, Juergens KU, Biassoni L, Begent J, Kluge R, Amthauer H, Voelker T, Højgaard L, Barrington S, Hain S, Lynch T, Hahn K. Guidelines for 18F-FDG PET and PET-CT imaging in paediatric oncology. Eur J Nucl Med Mol Imaging. 2008;3(8):1581–1588. doi: 10.1007/s00259-008-0826-x.

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