Technical Considerations of Phosphorous-32 Bremsstrahlung
SPECT Imaging after Radioembolization of Hepatic Tumors:
A Clinical Assessment with a Review of Imaging Parameters
Background. Bremsstrahlung (BS) imaging during radioembolization (RE) confirms the deposition of radiotracer in hepatic/
extrahepatic tumors. The aimof this study is to demonstrate 32P images and to optimize the imaging parameters. Materials and
Methods. Thirty-nine patientswith variable types of hepatic tumors, treatedwith the intra-arterial injection of 32P,were included. All
patients underwent BS SPECT imaging 24–72 h after tracer administration, using lowenergy high resolution (LEHR) (18 patients) or
medium energy general purpose (MEGP) (21 patients) collimators. A grading scale from1 to 4 was used to express the compatibility
of the 32P images with those obtained from CT/MRI. Results. Although the image quality obtained with theMEGP collimator was
visually and quantitatively better thanwith theLEHR(76%concordance score versus 71%, resp.), there was no statistically significant
difference between them. Conclusion.The MEGP collimator is the first choice for BS SPECT imaging. However, if the collimator
change is time consuming (as in a busy center) or an MEGP collimator is not available, the LEHR collimator could be practical
with acceptable images, especially in a SPECT study. In addition, BS imaging is a useful method to confirm the proper distribution
of radiotherapeutic agents and has good correlation with anatomical findings
