TY - JOUR T1 - <strong>Image metrics to quantify visual impression of <sup>18</sup>F-FDG PET heterogeneity in diagnosing cardiac sarcoidosis</strong> JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 451 LP - 451 VL - 61 IS - supplement 1 AU - Kenneth Nichols AU - Josephine Rini AU - David Chang AU - James Gabriels AU - Amtul Mansoor AU - Haisam Ismail AU - Christopher Palestro Y1 - 2020/05/01 UR - http://jnm.snmjournals.org/content/61/supplement_1/451.abstract N2 - 451Objectives: Results of combined 99mTc-MIBI myocardial SPECT/CT (SPECT/CT) &amp; 18F-FDG-PET/CT (PET/CT) studies for cardiac sarcoidosis typically are based on a subjective visual impression of 18F perfusion pattern heterogeneity, often referred to as “patchiness.” Our investigation was undertaken to determine whether there are any quantitative image metrics that correspond to 18F PET/CT &amp; perfusion heterogeneity &amp; abnormal SPECT/CT visual interpretation. Methods: 92 combined SPECT/CT &amp; PET/CT studies were performed on 69 pts (21 female; 48 male; age = 58±9 yrs) with cardiac arrhythmias &amp;/or non-ischemic cardiomyopathies. Pts fasted for at least 18 hrs &amp; followed a low carbohydrate/high fat diet on the day prior to the examination. Myocardial SPECT/CT was performed first, 45 min following injection of 370 MBq 99mTc-MIBI. PET/CT of the heart was performed 90 min following injection of 370-444 MBq 18F-FDG. A single experienced individual reviewed all scans. PET/CT scans were interpreted as positive (focal or focal on diffuse myocardial uptake of FDG greater than left ventricular blood pool activity), negative (myocardial FDG activity equal or less than left ventricular blood pool activity) or indeterminate (diffuse, uniform, segmental myocardial uptake of FDG, possibly related to incomplete suppression of physiologic myocardial glucose uptake or multiple granulomas) for cardiac sarcoidosis. SPECT/CT was interpreted as abnormal when there were perfusions defects, typically in a non-coronary artery distribution. Semi-automated cardiac analysis software generated polar maps of 18F-FDG &amp; 99mTc-MIBI myocardial perfusion. Algorithms written in IDL v 8.4 converted jpg files of perfusion polar maps to count distributions analyzed for pattern analysis metrics that included count distribution skewness (a measure of curve asymmetry) &amp; count distribution kurtosis (a measure of curve flatness). Results: Among the 92 PET/CT studies 32 were positive, 42 were negative &amp; 18 were indeterminate. PET/CT count distribution kurtosis was similar for positive &amp; indeterminate PET/CT studies (-0.98±1.09 versus -0.88±1.33, p = 0.78), but different from negative PET cases (-1.74±0.16, p &lt; 0.001). PET/CT count distribution skewness also was similar for positive &amp; indeterminate PET/CT studies (0.74±0.35 versus 0.78±0.45, p = 0.65), but different from negative PET cases (0.45±0.08, p &lt; 0.001). Grouping the positive and indeterminate readings into 50 abnormal PET/CT readings, the metric with the highest accuracy (greatest ROC AUC) coinciding with an abnormal PET/CT reading was count distribution curve kurtosis (sensitivity = 84%, specificity = 76%, accuracy = 86±4%, p &lt; 0.0001). Abnormal PET/CT cases had greater image contrast than negative studies (53±26% versus 25±13%, p &lt; 0.001). For SPECT/CT studies, excluding 6 that were deemed suboptimal, 50 were abnormal &amp; 36 were negative. Similar to PET/CT cases, abnormal SPECT/CT cases had greater count distribution curve kurtosis (-1.10±0.98 versus -1.57±1.10, p = 0.006), &amp; greater skewness (0.73±0.54 versus 0.54±0.10, p = 0.001), with greater image contrast (74±19% versus 58±23%, p = 0.001), than negative SPECT/CT studies. Conclusions: Image count distribution metrics of 18F-FDG-PET/CT &amp; 99mTc-MIBI SPECT/CT LV myocardial perfusion successfully reflected subjective perfusion heterogeneity visual readings, &amp; thus may aid in quantifying whether therapeutic interventions to treat cardiac sarcoidosis demonstrate a measureable beneficial effect in individual pts. ER -