Ultrafast 30-Second Total-body PET/CT Scan: A Preliminary Study

Introduction: The aim of this study is to explore the diagnostic value of the images obtained in ultrafast 30 sec acquisition time by the total-body PET/CT(with the injection dose of ¹⁸F-FDG about 3.7MBq/kg), and to evaluate whether they can meet the requirements of clinical diagnosis or not.

Methods: This retrospective study explored the clinical value of ultrafast 30-s ¹⁸F-FDG total-body PET/CT in 88 oncology patients, using the post-surgical pathological diagnosis as the reference standard. The data were acquired over 300 s and reconstructed using all 300-s data (G300) and only the initial 30 s (G30). Two raters independently assessed all images qualitatively and quantitatively. Malignant lesion detectability and the diagnostic efficacy were compared.

Results: The average score of G300(4.8±0.4) was higher than G30(2.8±0.7), and the difference between the two groups was statistically significant(P<0.001). The difference of the SUV_max, SD and SNR in the liver and the mediastinum was significant between G300 and G30 (all P < 0.001).Box plots comparing G300 and G30 for SUV_max and SD in the liver and mediastinum are shown in Fig. 1.The malignant lesion detectability of G300 and G30 was 89.09%(98/110) and 86.36%(95/110) respectively, and the difference between the two groups was not statistically significant (P=0.250). The accuracy of G300 (79.73%) is higher than that of G30 (77.70%), and the AUC of G300(0.709) was higher than that of G30(0.695), but the difference between the two groups was not statistically significant (all P >0.05).

Conclusions: The pathological diagnosis after a surgery was performed in all cases included in this study acted as a "gold standard." The results showed that the image quality when the acquisition time was reduced to 30 s was inferior to 300-s acquisition time; however, the two acquisition times had similar rates of qualified images for diagnosing without rescanning, malignant lesion detectability, and diagnostic efficacy. Therefore, images acquired through 30-s total-body PET/CT could meet the requirements of clinical diagnosis for patients with malignant tumors and poor tolerance to maintaining prolonged horizontal position.

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