Fewer-Angle SPECT/CT Blood Pool Imaging for Infection and Inflammation.

A new protocol for rapid SPECT/CT blood pool imaging consisting of fewer image-angle acquisitions (fewer-angle SPECT/CT, or FASpecT/CT) was evaluated for localization of focal sites of soft-tissue inflammation, infection, and osteomyelitis. Methods: Immediately after dynamic flow and standard planar blood pool imaging with 99mTc-methylene diphosphonate, FASpecT/CT was performed with a dual-head γ-camera consisting of 6 steps over 360°, 12 total images with 30° of separation between angles, and 30 s per image, requiring a total imaging time of approximately 3 min. Images were reconstructed using iterative ordered-subset expectation maximization. Before use in a patient-care setting, various FASpecT/CT acquisition protocols were modeled using a phantom to determine the minimum number of stops and the stop duration required to produce a reliable image. Results: FASpecT/CT images provided excellent 3-dimensional localization of spine osteomyelitis, soft-tissue infection of the foot, and tendonitis of the hand and foot using a 3-min image acquisition time. The FASpecT/CT acquisition protocol required 1.3-3.5 min, including camera movement time. This was a reduction of 72%-90% from the time required for the standard 60-angle, 20-s SPECT/CT acquisition. Conclusion: The ability of FASpecT/CT blood pool images to help localize focal sites of hyperemia and inflammation can increase exam sensitivity and specificity. Additionally, using a FASpecT/CT protocol decreases imaging time by up to 90%.

FASpecT/CT, A New SPECT/CT Acquisition With Higher Sensitivity and Efficiency in Radioiodine Thyroid Cancer Imaging.

PURPOSE: This article demonstrates the use of a new SPECT/CT acquisition protocol in patients with differentiated thyroid cancer (DTC). METHODS: SPECT/CT scans (FASpecT/CT) with fewer angle acquisitions were retrospectively reviewed in 30 DTC patients treated with radioiodine at University Hospital, San Antonio, Tex, from July 2017 to March 2019. This FASpecT/CT of 12 versus 60 to 64 sampled views for convention SPECT was made possible by iterative reconstruction. RESULTS: The FASpecT/CT protocol was judged to increase lesion detection in patients with low count rates. Furthermore, in patients with higher count rates, this technique reduced the acquisition time. FASpecT/CT patient images are shown as case examples in 4 of the 30 patients reviewed. CONCLUSIONS: This FASpecT/CT acquisition in radioiodine-treated DTC offers the potential of higher sensitivity for metastatic lymph node detection in low count rates and a significant decrease in imaging time in high count rates. These advantages make SPECT/CT imaging more acceptable for patients who have difficulty with longer imaging times, to include the pediatric population.