Sympathetic cardiac function in early sepsis: Noninvasive evaluation with [123I]-meta-iodobenzylguanidine (123I-MIBG) in vivo SPECT imaging

Abstract

Background: Sympathetic system abnormalities have been reported in sepsis-related cardiac dysfunction. The present study aimed at evaluating the potential of the norepinephrine radiolabeled analogue [¹²³I]-meta-iodobenzylguanidine (¹²³I-MIBG) for the noninvasive assessment of modifications in cardiac sympathetic activity occurring in lipopolysaccharide (LPS)-induced experimental acute sepsis by single-photon emission computed tomographic imaging (SPECT).

Methods and results: Sepsis was induced in male Wistar rats by intraperitoneal injection of 10 mg·kg^-1 lipopolysaccharide (n = 16), whereas control animals (n = 7) were injected with vehicle (NaCl 0.9%). Echocardiography in LPS-injected animals (n = 8) demonstrated systolic and diastolic cardiac dysfunction. ¹²³I-MIBG was injected 1 hour after LPS or vehicle administration (n = 8 and 7, respectively), and in vivo SPECT imaging was performed early and late (20 and 180 minutes) after tracer injection prior to animal euthanasia and ex vivo assessment of ¹²³I-MIBG biodistribution. Global and 17-segment SPECT image analysis indicated that early ¹²³I-MIBG activity was not affected by LPS treatment, whereas late cardiac tracer activity was significantly decreased in LPS-treated animals. Consequently, the cardiac washout of ¹²³I-MIBG was significantly higher in LPS-treated (63.3% ± 4.0%) than that in control animals (56.7% ± 5.8%) (P < .05).

Conclusion: Sepsis-induced modifications in cardiac sympathetic nervous system activity were evidenced by noninvasive in vivo ¹²³I-MIBG SPECT imaging.

Keywords: Basic science; MIBG imaging; experimental sepsis; microSPECT imaging.