Protocol for measuring myocardial blood flow by PET/CT in cats

Jenni, Simone ; Schepis, Tiziano ; Jenni, Rolf ; Siegrist, Patrick ; Kaufmann, Philipp ; Glaus, Tony

In: European Journal of Nuclear Medicine and Molecular Imaging, 2009, vol. 36, no. 2, p. 244-249

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    Purpose: The aim of this study was to establish a protocol for measuring myocardial blood flow (MBF) by PET/CT in healthy cats. The rationale was its future use in Maine Coon cats with hypertrophic cardiomyopathy (HCM) as a model for human HCM. Methods: MBF was measured in nine anaesthetized healthy cats using a PET/CT scanner and 13NH3 at rest and during adenosine infusion. Each cat was randomly assigned to receive vasodilator stress with two or three adenosine infusions at the following rates (μg/kg per minute): 140 (Ado1, standard rate for humans), 280 (Ado2, twice the human standard rate), 560 (Ado4), 840 (Ado6) and 1,120 (Ado8). Results: The median MBF at rest was 1.26ml/min per g (n = 9; range 0.88-1.72ml/min per g). There was no significant difference at Ado1 (n = 3; median 1.35, range 0.93-1.55ml/min per g; ns) but MBF was significantly greater at Ado2 (n = 6; 2.16, range 1.35-2.68ml/min per g; p < 0.05) and Ado4 (n = 6; 2.11, 1.92-2.45ml/min per g; p < 0.05). Large ranges of MBF values at Ado6 (n = 4; 2.53, 2.32-5.63ml/min per g; ns) and Ado8 (n = 3; 2.21, 1.92-5.70ml/min per g; ns) were noted. Observed adverse effects, including hypotension, AV-block and ventricular premature contractions, were all mild, of short duration and immediately reversed after cessation of the adenosine infusion. Conclusion: MBF can be safely measured in cats using PET. An intravenous adenosine infusion at a rate of 280μg/kg per minute seems most appropriate to induce maximal hyperaemic MBF response in healthy cats. Higher adenosine rates appear less suitable as they are associated with a large heterogeneity in flow increase and rate pressure product, most probably due to the large variability in haemodynamic and heart rate response