Advances in SPECT for Optimizing the Liver Tumors Radioembolization Using Yttrium-90 Microspheres

Abstract

Radioembolization (RE) with Yttrium-90 (90Y) microspheres is an effective treatment for unresectable liver tumors. The activity of the microspheres to be administered should be calculated based on the type of microspheres. Technetium-99m macroaggregated albumin (99mTc-MAA) single photon emission computed tomography/computed tomography (SPECT/CT) is a reliable assessment before RE to ensure the safe delivery of microspheres into the target. 90Y bremsstrahlung SPECT imaging as a posttherapeutic assessment approach enables the reliable determination of absorbed dose, which is indispensable for the verification of treatment efficacy. This article intends to provide a review of the methods of optimizing 90Y bremsstrahlung SPECT imaging to improve the treatment efficacy of liver tumor RE using 90Y microspheres.

Quantitative Imaging for Targeted Radionuclide Therapy Dosimetry - Technical Review

“…PET possesses great potential for TRT due to its superior imaging characteristics and quantification, but availability of the technique and isotope is less widespread than SPECT/CT. For imaging gamma emitters such as I-131 and In-111, quantification errors within 10% can been obtained with different combinations of compensation 62 . For imaging positron emitters like Y-86 and I-124, quantitative errors are within 7% 81 .…”

“…This reduced the Y-90 activity quantitation error for all organs-of interest, especially the kidneys, by up to 27%. Roshan et al reviewed the energy window selection, collimator design and reconstruction algorithm for Y-90 labeled microsphere bremsstrahlung imaging 62 . With a conventional medium energy general purpose collimator, a multiple-energy window with three energy peaks centered at 75 keV, 120 keV, and 185 keV with CT based AC and SC could achieve the highest system sensitivity and the lowest imaging acquisition time.…”

Imaging Evaluation Following 90Y Radioembolization of Liver Tumors: What Radiologists Should Know

“…Although SPECT/CT is not essential in dosimetry, it can provide more reliable assessment of 99m Tc-MAA distribution on fusion images ( Fig. 1 ), which may be useful to predict tumor response, to detect unexpected perfusion outside of the liver, and to elaborate dosimetry of the partition model ( 15 ). If radioactivity is detected in the non-target organs on 99m Tc-MAA scan, prophylactic embolization can be performed or catheter position can be modified at the time of the procedure to avoid severe complications ( 13 ).…”

Phantom-based evaluation of yttrium-90 datasets using Biograph Vision Quadra

“…Modern positron emission tomography with computed tomography scanners (PET/CTs) can overcome the limitations arising from the low count statistics of the extraordinary small branching ratio (32 ppm) [11] based on their overall higher sensitivity performance. Speci cally, for the post-treatment dosimetry evaluation, which is important for assessing the outcome of the irradiation of the tumor lesions, PET has been gaining favor due to its higher spatial resolution and higher quantitative accuracy compared to SPECT [6,8,9,[12][13][14]. The increased use of PET for SIRT imaging has been made possible by the introduction of TOF PET (12,13), which reduces the noise and serves as an effective sensitivity increaser: such an effect is known to be directly connected to the time resolution of PET scanner [15].…”

“…Single photon emission computed tomography (SPECT) has been regarded the standard for the posttreatment dosimetry validation [6,7]. However, the Y-90 Bremsstrahlung SPECT imaging presents certain challenges [6,8,9] such as dominant photon scatter, collimator septal penetration and limited spatial resolution [10].…”