A modified TEW approach to scatter correction for In‐111 and Tc‐99m dual‐isotope small‐animal SPECT

Prior, Paul; Timmins, Rachel; Petryk, Julia; Strydhorst, Jared; Duan, Yin; Wei, Lihui; Wells, R. Glenn

doi:10.1118/1.4962469

Cited by 7 publications

(5 citation statements)

References 29 publications

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“…The slower clearance of liposomes compared to small-molecule drugs has been exploited to demonstrate improvements in scanner technology. Wirwarr et al used 111 In-labelled liposomes to demonstrate the high sensitivity and temporal resolution of a multiple-pinhole SPECT system [297], and Prior et al used similar liposomes to improve scatter correction in dual-radionuclide SPECT [298]. Combined with sub-millimetre spatial resolution, such technological advances have played a great part in keeping SPECT radionuclides relevant in preclinical research despite the gradual shift towards the use of PET in the clinic.…”

Section: Applications Of Radiolabelled Liposomesmentioning

confidence: 99%

Nuclear imaging of liposomal drug delivery systems: A critical review of radiolabelling methods and applications in nanomedicine

Man

Gawne

Rosales

2019

Advanced Drug Delivery Reviews

124

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The integration of nuclear imaging with nanomedicine is a powerful tool for efficient development and clinical translation of liposomal drug delivery systems. Furthermore, it may allow highly efficient imaging-guided personalised treatments. In this article, we critically review methods available for radiolabelling liposomes. We discuss the influence that the radiolabelling methods can have on their biodistribution and highlight the often-overlooked possibility of misinterpretation of results due to decomposition in vivo. We stress the need for knowing the biodistribution/pharmacokinetics of both the radiolabelled liposomal components and free radionuclides in order to confidently evaluate the images, as they often share excretion pathways with intact liposomes (e.g. phospholipids, metallic radionuclides) and even show significant tumour uptake by themselves (e.g. some radionuclides). Finally, we describe preclinical and clinical studies using radiolabelled liposomes and discuss their impact in supporting liposomal drug development and clinical translation in several diseases, including personalised nanomedicine approaches.

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Section: Applications Of Radiolabelled Liposomesmentioning

confidence: 99%

Nuclear imaging of liposomal drug delivery systems: A critical review of radiolabelling methods and applications in nanomedicine

Man

Gawne

Rosales

2019

Advanced Drug Delivery Reviews

124

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“…These results, however, might not be fully applicable to clinical systems as the amount of scatter in human studies is substantially higher than that of small animals and therefore the effectiveness of the aforementioned method to remove crosstalk might be low. This challenge could be addressed by developing alternative modified TEW methods which have shown improvement of the quantification accuracy in 111 In/ 99m Tc dual tracers in smallanimal SPECT compared to the standard TEW (Prior et al 2016). On the other hand, the combination of 111 In and 67 Ga in clinical studies might not be desired due to the potentially high radiation delivered to patients as both isotopes have long half-lives.…”

Section: Recommendations and Limitations Of The Studymentioning

confidence: 99%

Dual SPECT imaging of ¹¹¹In and ⁶⁷Ga to simultaneously determine in vivo the pharmacokinetics of different radiopharmaceuticals: a quantitative tool in pre-clinical research

et al. 2018

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Dual-isotope (DI) studies offer a number of advantages in pre-clinical imaging. These include: reducing study times when compared with sequential scans, reducing the number of animals required for any given study, and most importantly, producing images perfectly registered in space and time that provide simultaneous information about two distinct body functions. The ability of single photon emission computed tomography (SPECT) to measure and differentiate energies of the emitted photons makes it well suited for DI imaging. However, since scattered photons originating from one radioisotope may be detected in the energy window of the other and thus degrade image quality and quantitative accuracy, scatter and crosstalk corrections must be applied. The decay characteristics of 111In and 67Ga, which are suitable for quantitative DI imaging for up to 2 weeks post-injection, led us to investigate the performance of simultaneous 111In/67Ga SPECT imaging using a small-animal pre-clinical scanner. A series of phantom experiments were performed to investigate image quality and accuracy of activity quantification in 111In/67Ga images acquired with three different collimators and reconstructed from different photopeak combinations. The triple energy window (TEW) method was used to correct for scatter and crosstalk. Based on these phantom studies, the optimal selection of collimator and energy window settings was determined. When using these optimal settings, submillimeter-size structures were distinguishable in the reconstructed images and quantification errors below 20% were achieved for both isotopes. The optimal parameters were subsequently applied to an in vivo animal study. The determination of the distinct pharmacokinetic profiles of two polymer radiopharmaceuticals injected simultaneously, but by different administration routes (intravenously and intraperitoneally) into a single animal demonstrated the feasibility of simultaneous 111In/67Ga SPECT.

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“…In these applications, gamma-rays across a wide energy range (60-700 keV) are emitted. In the presence of multi-energy gamma-rays like Ac-225 and In-111/Tc-99m or Ga-68/Lu-177 dual-tracers, downscattering and crosstalk could significantly degrade the image quality of SPECT imaging [5][6] [7]. As illustrated in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Over the years, numerous correction methods have been proposed to mitigate these issues. Energy window-based correction methods like dual/triple/multiple energy window correction use several energy windows to estimate the scatter imaging and are widely applied [5][8] [9][10] [11] [12]. There are also correction methods based on spectral analysis, including spectra fitting to split the primary photopeak and gain high accuracy [13][14] [15].…”

Section: Introductionmentioning

confidence: 99%

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Exploration of Coincidence Detection of Cascade Photons to Enhance Preclinical Multi-Radionuclide SPECT Imaging

Jin,

Meng

2024

IEEE Trans. Med. Imaging

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We proposed a technique of coincidence detection of cascade photons (CDCP) to enhance preclinical SPECT imaging of therapeutic radionuclides emitting cascade photons, such as Lu-177, Ac-225, Ra-223, and In-111. We have carried out experimental studies to evaluate the proposed CDCP-SPECT imaging of lowactivity radionuclides using a prototype coincidence detection system constructed with large-volume cadmium zinc telluride (CZT) imaging spectrometers and a pinhole collimator. With In-111 in experimental studies, the CDCP technique allows us to improve the signal-to-contamination in the projection (Projection-SCR) by ~53 times and reduce ~98% of the normalized contamination. Compared to traditional scatter correction, which achieves a Projection-SCR of 1.00, our CDCP method boosts it to 15.91, showing enhanced efficacy in reducing down-scattered contamination, especially at lower activities. The reconstructed images of a line source demonstrated the dramatic enhancement of the image quality with CDCP-SPECT compared to conventional and triple-energywindow-corrected SPECT data acquisition. We also introduced artificial energy blurring and Monte Carlo simulation to quantify the impact of detector performance, especially its energy resolution and timing resolution, on the enhancement through the CDCP technique. We have further demonstrated the benefits of the CDCP technique with simulation studies, which show the potential of improving the signal-to-contamination ratio by 300 times with Ac-225, which emits cascade photons with a decay constant of ~0.1 ns. These results have demonstrated the potential of CDCP-enhanced SPECT for imaging a superlow level of therapeutic radionuclides in small animals.

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A modified TEW approach to scatter correction for In‐111 and Tc‐99m dual‐isotope small‐animal SPECT

Cited by 7 publications

References 29 publications

Nuclear imaging of liposomal drug delivery systems: A critical review of radiolabelling methods and applications in nanomedicine

Nuclear imaging of liposomal drug delivery systems: A critical review of radiolabelling methods and applications in nanomedicine

Dual SPECT imaging of ¹¹¹In and ⁶⁷Ga to simultaneously determine in vivo the pharmacokinetics of different radiopharmaceuticals: a quantitative tool in pre-clinical research

Exploration of Coincidence Detection of Cascade Photons to Enhance Preclinical Multi-Radionuclide SPECT Imaging

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A modified TEW approach to scatter correction for In‐111 and Tc‐99m dual‐isotope small‐animal SPECT

Cited by 7 publications

References 29 publications

Nuclear imaging of liposomal drug delivery systems: A critical review of radiolabelling methods and applications in nanomedicine

Nuclear imaging of liposomal drug delivery systems: A critical review of radiolabelling methods and applications in nanomedicine

Dual SPECT imaging of 111In and 67Ga to simultaneously determine in vivo the pharmacokinetics of different radiopharmaceuticals: a quantitative tool in pre-clinical research

Exploration of Coincidence Detection of Cascade Photons to Enhance Preclinical Multi-Radionuclide SPECT Imaging

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Dual SPECT imaging of ¹¹¹In and ⁶⁷Ga to simultaneously determine in vivo the pharmacokinetics of different radiopharmaceuticals: a quantitative tool in pre-clinical research