Correlation Between CT Perfusion and Post Y-90 TARE PET/CT Dosimetry

The overreaching goal of this line of research is to establish a methodology to produce
patient and tumor specific treatment planning for Yttrium-90 radioembolization of
hepatocellular carcinoma (HCC). The proposed project will facilitate the collection of
preliminary data to support a larger study to more fully establish the relationship between
tumor perfusion parameters and delivered radiation dose. Y-90 radioembolization delivers
millions of small resin or glass beads attached to or containing (depending on the product)
the beta emitting radioisotope of Yttrium. These beads are injected into the patient's
hepatic artery during an interventional radiology procedure. The beads are pushed into the
hepatic vasculature system by pulsatile flow and eventually become lodged, due to their
finite size, in the microvasculature of the liver and tumor and deliver the radiation dose
from the high energy beta particles (average energy 0.94 MeV) released during the radioactive
decay (half life of 64 hours) in a highly local (~2.5 mm range) manner. The beads are
permanently embedded in the vasculature and the radioactivity eventually decays to
background.

Current practice is to calculate and deliver an average liver lobe radiation dose based on
either the lobar volume or the patient's body surface area. However, because of the
hypervascular nature of HCC lesions, the tumors receive a greater proportion of the beads
than the healthy liver parenchyma and hence are assumed to receive radiation doses well above
that of calculated average liver dose and the dose to the normal liver. Due to the differing
vascularity and characteristics of tumors and patients, each Y-90 treatment does not deliver
the same dose to the tumor. A less vascular tumor may receive substantially less radiation
than a more vascular one which affects the tumoricidal efficacy of the treatment and
ultimately the patient's final outcome. New techniques using Positron Emission Tomography
(PET)/CT following Y-90 treatment allow for retrospective dosimetry to determine the actual
dose delivered to the tumor. However, no methodology exists to plan the dose to be delivered
to the tumor prior to the treatment.

This research aims to collect preliminary data to begin to establish a prospective method to
use Computed Tomography (CT) perfusion studies of the liver to calculate the expected dose to
the HCC lesions and the normal liver based on the blood flow and blood volume. This goal will
be achieved by prospectively collecting CT Perfusion studies prior to Y-90 radioembolization
treatments and PET/CT immediately following treatments. The relationship between the
perfusion parameters representing the vascularity of the lesions and the normal liver and the
post treatment PET/CT dosimetry will be established by this line of research. The
hypothesized correlation between the perfusion parameters and the tumor dose as established
by PET/CT will allow for patient and tumor specific treatment planning ensuring that the
appropriate tumoricidal radiation dose is reliably delivered.

Inclusion Criteria:

- Hepatocellular Carcinoma diagnosis

- Candidate for Trans-Arterial Radioembolization treatment

Exclusion Criteria:

- Less than 18 years old

- Pregnant

- Iodinated Contrast Agent Allergy