Usefulness of Bremsstrahlung Images after Intra-arterial Y-90 Resin Microphere Radioembolization for Hepatic Tumors

Abstract

Purpose Y-90 resin microsphere radioembolization is used to treat inoperable hepatic tumors. After injection of Y-90 resin microsphere, the only method to visualize the distribution of Y-90 is the scintigraphic imaging of bremsstrahlung radiation. The purpose of this study was to evaluate the characteristics and usefulness of bremsstrahlung imaging in Y-90 resin microsphere treatment. Methods Twenty patients (22 administrations) underwent intra-arterial Y-90 resin microsphere treatment. For pretreatment planning, images of Tc-99m albumin macroaggregate (MAA) arterial injection and hepatic contrast angiography were obtained. Post-treatment bremsstrahlung images were taken and compared with pre-treatment images. The extrahepatic activity was evaluated on bremsstrahlung images. To correlate the size and vascularity of the tumors with tumor visualization on bremsstrahlung images, the individual tumors were grouped according to visualization on each image and compared with one another by size and tumor-to-normal ratio. Results All post-therapeutic bremsstrahlung images showed similar contours of the liver with pre-treatment angiography. No extrahepatic activity was seen in all cases. The visualized tumors on bremsstrahlung images were significantly larger than the non-visualized tumors. Tumor-to-normal ratios of the visualized tumors on bremsstrahlung images were significantly higher than those of the non-visualized tumors. Conclusions Bremsstrahlung images after intra-arterial Y-90 resin microsphere treatment are useful in evaluating the intrahepatic distribution of radioisotope and detecting possible extrahepatic activity.

Lutathera®: The First FDA- and EMA-Approved Radiopharmaceutical for Peptide Receptor Radionuclide Therapy

“…Since 90 Y does not emit suitable γ-rays, a detection of the radiopharmaceutical after administration is difficult. It is possible by Bremsstrahlung scintigraphy or PET using SPECT or PET scanners [21,22], but this yields only low quality images in comparison to state-of-the-art SPECT and PET images where typical SPECT or PET radionuclides are used.…”

Management of unresectable intrahepatic cholangiocarcinoma: how do we decide among the various liver-directed treatments?

“…This therapy is also challenged by the lack of a validated method to measure the dose of radiation that is delivered to the tumor. For example, Bremsstrahlung imaging methods have been developed to address the dosimetry (44), but remains to be fully utilized in clinical practice. Other methods have been developed also, and each has uncertainties (45).…”

Semi-Quantitative Analysis of Post-Transarterial Radioembolization 90Y Microsphere Positron Emission Tomography Combined with Computed Tomography (PET/CT) Images in Advanced Liver Malignancy: Comparison With 99mTc Macroaggregated Albumin (MAA) Single Photon Emission Computed Tomography (SPECT)

“…When combined with SPECT imaging, bremsstrahlung SPECT/CT showed more accurate anatomical localization of 90 Y microspheres [26]. In spite of these characteristics of the bremsstrahlung image, the major drawbacks are the low spatial resolution and long image acquisition time, which would lead to lower tumor-to-normal ratios compared to the 99m Tc MAA images [27]. Moreover, 99m Tc MAA images are not considered to be ideal method to predict the actual distribution of the 90 Y microspheres.…”