Effect of gravity on drug distribution after port-catheter implantation for hepatic arterial infusion chemotherapy: evaluation of the relationship between the injection posture and intrahepatic perfusion on fused images acquired with a combined SPECT/CT system.

ABSTRACT

RATIONALE AND OBJECTIVES: We evaluated the effect of gravity on intrahepatic perfusion (IHP) in patients with a port-catheter system (PCS) implanted for hepatic arterial infusion chemotherapy (HAIC). Using fused single photon-emission computed tomographic (SPECT)/computed tomographic (CT) images, we compared IHP after the injection of technetium-99m-labeled macroaggregated albumin (Tc-99m-MAA) via a PCS with the patient in the upright and decubitus positions. MATERIALS AND METHODS: We enrolled 27 patients with metastatic carcinoma of the liver who bore an implantable PCS for HAIC. SPECT/CT images were obtained on the third and seventh postimplantation day; 99mTc-MAA (185 MBq) was delivered with the patient in the upright and decubitus positions. We selected four regions of interest (ROIs) on SPECT images of the superior, inferior, anterior, and posterior regions. The anteroposterior and the superoinferior perfusion ratio (AP ratio, SI ratio) were derived from the mean counts in each ROI. Using an unpaired t-test, we compared these ratios after drug delivery in the upright and decubitus injection positions. We also visually compared IHP and classified the distribution of drugs delivered in the upright and decubitus positions on fused images. Moreover, using World Health Organization criteria, we evaluated the therapeutic response by comparing the tumor size on contrast-enhanced CT images obtained before and 3 months after treatment. RESULTS: The SI ratios in the upright and decubitus injection positions were 1.14 and 0.92, respectively; the corresponding AP ratios were 1.47 and 1.73, respectively, indicating that there was no significant difference in these parameters irrespective of the injection position (SI ratio P = .27, AP ratio P = .35). However, in 14 of the 27 patients (52%), the visual appearance of IHP was different in the upright and decubitus positions. A change in the location of the catheter side hole when the decubitus was changed to the upright position produced a difference in IHP. Of 13 patients with identical drug distribution in both injection positions, six (46%) manifested a partial response (PR), five (38%) experienced no change (NC), and two (15%) experienced progressive disease (PD). Among the 14 patients with different drug distribution in the two injection positions, four (28%) achieved PR, five (36%) manifested NC, and the other five (36%) had PD. CONCLUSIONS: Although the patient posture affected IHP by changing the position of the infusion catheter side hole in the liver, gravity had no significant effect on IHP in patients bearing an implantable PCS for the delivery of HAIC.