Symbia t2

Whole-body activity retention was determined in all patients by combining external dose rate measurements and whole-body gamma camera scans. For the first measurement, the patients were asked not to micturate or defaecate after administration of the radiopharmaceutical. Prior to subsequent measurements they were asked to micturate. The dose-rate measurements were performed using a ceiling-mounted shielded survey meter (automess–Automation und Messtechnik, Germany) at a fixed distance of 2.5 m above the patient’s bed. The patient measurements were carried out immediately after administration and at least two times per day thereafter. The data were normalized to the first initial measurement. In addition, whole-body scans with a gamma camera (Symbia T2; Siemens Healthcare, Germany) were performed 1 h and 24 h after administration (medium energy collimator, energy window 208 keV ±10 %). In selected patients, an additional scan was performed 4 h after treatment. The gamma camera whole-body retention was calculated by normalizing the geometric mean of subsequent background-corrected anterior and posterior counts to the initial measurement. Both datasets were combined to obtain the whole-body retention curve for each patient.

Gamma scintigraphy study was carried out using a dual head gamma camera system (Symbia T2, Siemens, Erlangen, Germany). Male New Zealand rabbits (n=3), weighing 2–3 kg were used in whole body scintigraphic studies. They were maintained on a normal diet. The animal was anesthetized by intramuscular administration of ketamine (15 mg/ kg). 2 mCi of ^99mTc-mannan complex was injected intravenously via ear vein. The anesthetized animal was placed in the supine position and scanned under the gamma camera. Anterior and posterior whole-body images were obtained after 10min, 2h, 4h and 24h.

Evaluation with ^99mTc-MAA was routinely performed in all patients with primary or secondary liver cancer and planned TARE. The angiographic procedures were performed by experienced interventional radiologists who were approved within the quality assurance program of the microsphere provider. Evaluation included embolization of aberrant vessels originating from the hepatic circulation. After ^99mTc-MAA application via a coaxial microcatheter system patients underwent planar whole body and SPECT/CT scanning of the thoracic and abdominal region (GE Discovery NM630 or Siemens Symbia T2) using low-energy collimators for dose calculation, detection of extrahepatic tracer accumulation and assessment of hepatopulmonary shunting. While parameters like feasibility to position the catheter and (abnormal) vascular anatomy were rated by interventional radiologists, ^99mTc-MAA associated parameters such as hepatopulmonary shunt fraction and extrahepatic tracer accumulation were rated by experienced physicists and nuclear medicine physicians.
⁹⁰Y radioembolization using resin microspheres (SIR-Spheres®; Sirtex Medical, Sydney, Australia) was performed according to standard operating procedures. The ⁹⁰Y dose was calculated based on the body surface area (BSA) method [Activity of SIR-Spheres in GBq = (BSA − 0.2) + (volume of tumor/volume of whole liver)].

Whole body Single-photon emission computed- tomography (SPECT)/Computed-Tomography (CT) (MEAP colimaters, Siemens medical solution, Symbia T2, Erlangem, Germany) was performed at 4 hours, 24 h, 96 h and 168 h after infusions. A CT scan was performed to delineate the organs of interest (liver, spleen, bone marrow) plus tumor volume. Concentration of radioactivity in each of these organs was determined on SPECT imaging by the count number in the respective volumes²¹ . The absorbed bone marrow dose was assessed on the L2-L4 lumbar area according to Shen et al.⁴³ .
The accurate processing of 3D images to confirm absorbed-dose calculations (using CT images to estimate patient-specific organ and bone marrow volumes) was centralised in the CRCNA laboratory (Nantes) as previously²¹ . All patients provided informed written consent. Ethics approval was granted in accordance with French and UK Medical Research Council guidelines and the Declaration of Helsinki (NCT01493479). All methods were performed in accordance with the relevant guidelines and regulations.