Patient Management Effects

We also analyzed data from two nuclear medicine centers – Carilion Clinic, Roanoke, VA and the University of Tennessee Medical Center, Knoxville, TN. In both centers, injection quality is routinely monitored by technologists using bilateral, external radiation detectors (Lara^® System, Lucerno Dynamics, Cary, NC, USA) that provide a real time display of counts after injection and prior to imaging. Once the administration is complete, nuclear medicine physicians also review this information now in the form of a time-activity curve (TAC) to evaluate the quality of radiopharmaceutical administration. Repeat imaging in these centers is routinely ordered for patients with extravasations that the interpreting nuclear medicine physician suspects would negatively affect the diagnostic value of the imaging study. For this report we selected five representative cases involving extravasated diagnostic radiopharmaceuticals: ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG) for Positron Emission Tomography/Computed Tomography (PET/CT) (N = 4) and ^99mTc-Methylene diphosphonate (^99mTc-MDP) for Single Photon Emission Computed Tomography (SPECT) (N = 1). Acquisition and reconstruction parameters for each site are described below.

At Carilion Clinic, when performing PET/CT the standard injected activity was 10mCi 18F-FDG using a standard step and shoot acquisition routine with axial range matched to the CT FOV. For CT Acquisition, data were acquired using 120 kVp with CareDose 4D. Data were acquired using a 20 × 0.6 mm detector setting with 5.0 mm slice thickness. For Bone SPECT the standard injected activity was 25mCi 99mTc-MDP using a LEHR collimator and matrix size of 256 × 256 with a zoom of 1. SPECT data were acquired using 30 views in a non-circular (body contour) orbit with an acquisition time of ~20 s per view. For CT Acquisition, data were acquired using 130 kVp with CareDose 4D and pitch of 1.5 and detector settings of 16 × 1.2 mm with 3 mm slice thickness. For visualization, both B80s AC for ECT and B50s medium sharp with bone window kernels were employed.

At University of Tennessee Medical Center, when performing PET/CT the standard injected activity was 10 mCi of 18F-FDG ±20%. Data were acquired using continuous bed motion acquisition with a bed speed of 1.5 mm/s. Reconstruction was performed using point spread function resolution recovery with time of flight (UltraHD PET, Siemens Healthineers, Malvern, PA). A matrix size of 200 × 200 was used with 3 iterations and 21 subsets and a Gaussian filter of 5 mm FWHM was applied. For CT, data were acquired using 120 kVp with CareDose 4D using a 5 mm acquisition technique reconstructed to 4 mm slice thickness and using a standard abdomen kernel.

All patients consented to publication of their images or were granted a waiver of consent by the local institutional review board. Attempts were made during the repeat studies to ensure that imaging parameters and patient preparation were as consistent as possible with the extravasated procedure to help assess extravasation effects. PET/CT scans were performed on the Biograph mCT camera (Siemens Healthineers, Knoxville, TN). SPECT scans were performed on the Symbia Intevo Bold™ camera (Siemens Healthineers, Knoxville, TN). Extravasated and repeated images were interpreted on the day of the procedure by a trained nuclear medicine physician and findings from the scan were recorded in the standard department reporting system.