The significance of Tc-99m-MAA SPECT-CT liver perfusion imaging in treatment planning for yttrium 90 microsphere selective internal radiation treatment

Objectives The aim of this study was to evaluate the impact of liver perfusion SPECT-CT images in comparison to planar and mere SPECT images on Y-90 radioembolization treatment planning.

Methods 82 diagnostic hepatic angiograms were performed for 73 Patients (17 CRC, 16 NEC, 14 HCC and 26 other types of tumors) altogether to assess vascularity of the hepatic tumors/metastases and to define the vascular anatomy prior to radioembolization with Y-90 microspheres. During the angiogram, 200-400 MBq Tc-99m MAA was administered intraarterially in each case to simulate the distribution of microspheres in the liver, lungs and extrahepatic abdominal tissue. Planar, whole body and SPECT-CT scans were performed as part of the pre-treatment planning. The studies were reviewed to evaluate whether the SPECT-CT imaging was of benefit.

Results SPECT-CT identified extrahepatic perfusion in a significant number of studies, not being visible on planar imaging. As the result, some patients underwent a repeat angiogram and coil embolization of accessory vessels. Furthermore SPECT-CT images permitted exact evaluation of MAA-distribution in the liver segments and exact measurement of tumor to background ratio. This additional information led to a change in treatment plan in a significant proportion of patients.

Conclusions The information from SPECT-CT images may lead to a change of the initial treatment plan, this is especially true regarding sparing of normal liver parenchyma and protection of gallbladder and the gastroenteropancreatic system.