TY - JOUR T1 - <strong>Value of Cardiac <sup>13</sup>N-Ammonia PET in Assessing Early Radiation-Induced Cardiotoxicity in Breast Cancer Patients Undergoing Radiotherapy: A Feasibility Study</strong> JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 517 LP - 517 VL - 58 IS - supplement 1 AU - Sadek Nehmeh AU - Josef Fox AU - Jazmin Schwartz AU - Ase Ballangrud AU - Heiko Schoder AU - Harry Strauss AU - Anthony Yu AU - Dipti Gupta AU - Simon Powell AU - John Humm AU - Alice Ho Y1 - 2017/05/01 UR - http://jnm.snmjournals.org/content/58/supplement_1/517.abstract N2 - 517Objectives: This is a pilot study to assess the value of the changes in myocardial hemodynamics, particularly myocardial flow reserve (MFR), in predicting cardiotoxicity induced by irradiation of the chest wall.Methods: 10 left-sided breast cancer patients underwent calcium scoring (CS) CT followed by rest/stress 13N-Ammonia PET at, baseline (BL) and a median of 13 months (range 10-17 months) post-Radiotherapy (RT). Left ventricular ejection fractions (LVEF’s) were calculated for the 2 studies and compared. Myocardial blood flow (MBF) and MFR were estimated for the myocardium, per coronary territory, and for each of 17 myocardium segments. The RT dose distribution map was registered to the 13N-Ammonia PET images in the standard nuclear medicine cardiac orientation. Changes in hemodynamics and CS between BL and post-RT were assessed, and correlated with the corresponding RT doses. Changes in MBF and MFR between BL and follow up (FU) were correlated with the corresponding RT dose to the myocardium, the 3 coronary territories, as well as on a segment-by-segment basis.Results: Agatston CS were consistent with a value of zero in both BL and FU scans in 75% of patients. The other patients showed slight increase in CS, yet fell in the mild risk range (10&lt;CS&lt;20). Heart rate, blood pressure, and rate-pressure product (RPP) showed insignificant (P&gt;0.3) differences between BL and FU. Rest and stress LVEF measurements were consistently normal (LVEF&gt;50) for all patients in both studies; no correlation existed between LVEF measurements and radiation dose. Global MBF's were (BL: 0.83+/-0.25 ml.g-1.min-1; FU: 0.92+/-0.30 ml.g-1.min-1) and (BL: 2.4+/-0.79 ml.g-1.min-1 ; FU: 2.76+/-0.71 ml.g-1.min-1) for the rest and stress respectively. Differences in MBF between BL and FU were not significant (P&gt;0.1) for either the rest or stress. Strong correlation between MBF and RPP for the rest study (R=0.79; P&lt;0.01) was depicted, yet insignificant correlation existed for the stress (P=0.37) data. Global MFR decreased from BL to FU by ~41% in 50% of patients. This effect was more evident in myocardial segments included in the radiation fields. Segment-wise analysis showed linear relationship (p&lt;0.05) between the change in MFR (between BL and FU) and the corresponding mean RT dose. Strong linear correlation (p&lt;0.05) was observed between the rate of change in MFR and the corresponding RT dose.Conclusion: Inverse linear relationship was depicted between changes in MFR due to RT and RT dose. MFR may have potential as an early predictor of cardiotoxicity in patients undergoing RT of the chest wall. Research Support: ER -