Protocol for measuring myocardial blood flow by PET/CT in cats.
OBJECTIVE
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 (13)NH(3) 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 (microg/kg per minute): 140 (Ado 1, standard rate for humans), 280 (Ado 2, twice the human standard rate), 560 (Ado 4), 840 (Ado 6) and 1,120 (Ado 8).


RESULTS
The median MBF at rest was 1.26 ml/min per g (n = 9; range 0.88-1.72 ml/min per g). There was no significant difference at Ado 1 (n = 3; median 1.35, range 0.93-1.55 ml/min per g; ns) but MBF was significantly greater at Ado 2 (n = 6; 2.16, range 1.35-2.68 ml/min per g; p < 0.05) and Ado 4 (n = 6; 2.11, 1.92-2.45 ml/min per g; p < 0.05). Large ranges of MBF values at Ado 6 (n = 4; 2.53, 2.32-5.63 ml/min per g; ns) and Ado 8 (n = 3; 2.21, 1.92-5.70 ml/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.


CONCLUSIONS
MBF can be safely measured in cats using PET. An intravenous adenosine infusion at a rate of 280 microg/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.
Jenni
Simone D
SD
Division of Cardiology, Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, CH-8057, Zurich, Switzerland.
Schepis
Tiziano
T
Jenni
Rolf
R
Siegrist
Patrick T
PT
Kaufmann
Philipp A
PA
Glaus
Tony M
TM
D000241:Adenosine / Q000009:adverse effects; D000818:Animals; D002312:Cardiomyopathy, Hypertrophic / Q000503:physiopathology; D002415:Cats; D003326:Coronary Circulation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006439:Hemodynamics; D006940:Hyperemia / Q000000981:diagnostic imaging / Q000503:physiopathology; D049268:Positron-Emission Tomography; D012016:Reference Values; D012146:Rest / Q000502:physiology; D014057:Tomography, X-Ray Computed
D000241:Adenosine