PT - JOURNAL ARTICLE AU - Yuuki Tomiyama AU - Kenji Hirata AU - Osamu Manabe AU - Masanao Naya AU - Keiichi Magota AU - Katsuhiko Kasai AU - Ken-ichi Nishijima AU - Chietsugu Katoh AU - Sung-Cheng Huang AU - Nagara Tamaki TI - Arterial input function does not influence the retention index of cardiac 11C -hydroxyephedrine positron emission tomography for sympathetic nervous system function. DP - 2015 May 01 TA - Journal of Nuclear Medicine PG - 541--541 VI - 56 IP - supplement 3 4099 - http://jnm.snmjournals.org/content/56/supplement_3/541.short 4100 - http://jnm.snmjournals.org/content/56/supplement_3/541.full SO - J Nucl Med2015 May 01; 56 AB - 541 Objectives 11C-Hydroxyephedrine (HED) has been the most frequently used PET tracer to image cardiac sympathetic nervous system (SNS) function. Although retention index (RI) has been most commonly used to quantify HED uptake, RI might be sensitive to arterial input function (AIF) and thus might mis-estimate SNS function in patients with heart failure (HF). We performed a simulation study to evaluate AIF effects on RI.Methods Before simulation, we obtained AIFs and time-activity curves (TAC) from left ventricular (LV) cavity and myocardium, respectively, of dynamic HED PET images (0-40 minutes) of 10 control subjects (32 ± 10 y.o.) and 9 HF patients (57 ± 17 y.o., LVEF: 36 ± 17 %). Individual K1 and k2 from a single compartment model were averaged by healthy and HD groups (K1C and k2C, and K1HF and k2HF, respectively). Then, individual AIF and (K1C and k2C) and (K1HF and k2HF) were used to generate a total of 19 simulated TAC of LV muscle, followed by RI computation by dividing averaged TAC (30-40 minutes) by area-under-curve of AIF (0-40 minutes).Results K1C and k2C were 0.20 ml/min/g and 0.016 1/min, respectively. K1HF and k2HF were 0.14 ml/min/g and 0.036 1/min, respectively. Using K1C and k2C, 10 AIFs from controls and 9 AIFs from HF patients generated highly reproducible RI values (0.132 ± 0.004 (range, 0.126 - 0.138) 1/min for control AIFs vs. 0.132 ± 0.001 (range, 0.131 - 0.134) 1/min) for HF AIFs (p=NS). Similarly, when K1HF and k2HF were used, AIFs calculated highly reproducible RI values (0.062 ± 0.002 (range, 0.055 - 0.071) 1/min for control AIFs vs. 0.063 ± 0.005 (range, 0.059 - 0.065) (p=NS) for HF AIFs. RIs estimated from (K1C and k2C) and (K1HF and k2HF) were significantly different with no overlapped case.Conclusions The simulation study suggested that RI reflected well the tissue physiology and was highly independent of the AIF, indicating the HED RI is reliable for indicating impaired SNS cardiac function.