Supplemental minimal‐activity PET/CT to validate ambiguous findings with less than 1 mSv: Proof of concept

Abstract

Summary Short‐term follow‐up examinations could verify ambiguous findings in PET/CT diagnostics, but are often avoided due to radiation and financial burdens. We demonstrate the feasibility of a focused, minimal‐activity PET protocol as a supplemental examination for uncertain findings after standard PET/CT. After changing conditions, e.g. patient positioning, preparation and bypassing an interval as well as a targeted tracer change, an additional examination with less than 1 mSv of additional radiation exposure was performed. Lowered administered activity of radiopharmaceuticals could be compensated by prolonged acquisition time, which was made possible by the limitation to a single body region. A sufficient visual and quantitative image quality of scans could be achieved. In all cases, the ambiguous finding could be clarified, so further diagnostic procedures or unnecessary interventions were avoided.

Warthin-Like Papillary Thyroid Microcarcinoma With Coincidental Ipsilateral Warthin Tumor of the Parotid Gland Detected on 131I-SPECT/US and 18F-PET/US Fusion Imaging

“…Furthermore, minimal-activity segmental PET/CT with application of 21 MBq 18 F-FDG was performed using a Biograph mCT40 scanner (Siemens Healthineers). 2 The additional hybrid sectional imaging examinations showed increased iodine (B1, white arrow) and glucose uptake (B2, white arrow) of a right-sided cervical lesion. Subsequently, we transferred the SPECT/CT and PET/CT data to a GE Logiq E9 US device (GE Healthcare, Milwaukee, WI) for the purpose of SPECT/US and PET/US fusion imaging.…”

“…Because the topographical alignment between the planar scintigraphy and the several US findings remained unclear and the possibility of a lymph node metastasis was considered, we decided to perform additional cervical 131 I-SPECT/CT using a Symbia Intevo scanner equipped with a high-energy collimator (Siemens Healthineers, Erlangen, Germany). Furthermore, minimal-activity segmental PET/CT with application of 21 MBq 18 F-FDG was performed using a Biograph mCT40 scanner (Siemens Healthineers) 2 . The additional hybrid sectional imaging examinations showed increased iodine ( B1 , white arrow) and glucose uptake ( B2 , white arrow) of a right-sided cervical lesion.…”