Use of CCK-8 to improve resting 99Tcm-MIBI cardiac scans

Full text: MIBI excretion is mainly hepatobiliary, and resting 99Tcm-MIBI studies can be compromised by abdominal activity, especially left subdiaphragmatic activity, presumably due to excretion into small bowel (SB). Retention of activity within the liver and biliary system can also impair scan quality. This study examined whether cholecystokinin (CCK) can: clear activity from SB; improve clearance of 99Tcm-MIBI from the liver and biliary system; improve image quality? 22 patients were divided into CCK (n 11) and control (n = 11) groups. The CCK group received 370 MBq of 99Tcm-MIBI at rest. At 30 min SPET was acquired. CCK-8 was then infused (0.01 μg.kg-1 over 3 min). 15 min later (70 min after intravenous MIBI), a second SPET was obtained. Controls had identical images, but no CCK. A physician blinded to CCK status graded the images for liver and SB activity, and overall scan quality. Liver and heart ROIs were drawn, count rates determined and comparisons made between groups and across time. In patients with SB activity initially interfering with the inferior wall, images post-CCK were dramatically better. Image quality at 70 min was significantly better than at 30 min in CCK and control groups. However, improvement in image quality and liver/heart count rate ratios was not significantly greater for the CCK group than for controls (P = 0.2). Liver activity reduced over time, but MIBI clearance from liver was not significantly increased by CCK. In conclusion: (1) CCK clears small bowel activity when present. It is useful when rest images are poor due to left subdiaphragmatic activity. (2) CCK does not increase clearance rate of 99Tcm-MIBI from liver. (3) The trend for CCK to improve image quality for all patients is not significant. CCK is thus not recommended for use in every patient