Long Versus Short Axial Field of View Immuno-PET/CT: Semiquantitative Evaluation for⁸⁹Zr-Trastuzumab

Abstract

The purpose of this study was to quantify any differences between the SUVs of 89 Zr immuno-PET scans obtained using a PET/CT system with a long axial field of view (LAFOV; Biograph Vision Quadra) compared to a PET/CT system with a short axial field of view (SAFOV; Biograph Vision) and to evaluate how LAFOV PET scan duration affects image noise and SUV metrics. Methods: Five metastatic breast cancer patients were scanned consecutively on SAFOV and LAFOV PET/CT scanners. Four additional patients were scanned using only LAFOV PET/CT. Scans on both systems lasted approximately 30 min and were acquired 4 d after injection of 37 MBq of 89 Zr-trastuzumab. LAFOV list-mode data were reprocessed to obtain images acquired using shorter scan durations (15, 10, 7.5, 5, and 3 min). Volumes of interest were placed in healthy tissues, and tumors were segmented semiautomatically to compare coefficients of variation and to perform Bland-Altman analysis on SUV metrics (SUV max , SUV peak , and SUVmean ). Results: Using 30-min images, 2 commonly used lesion SUV metrics were higher for SAFOV than for LAFOV PET (SUV max , 16.2% 6 13.4%, and SUV peak , 10.1% 6 7.2%), whereas the SUV mean of healthy tissues showed minimal differences (0.7% 6 5.8%). Coefficients of variation in the liver derived from 30-min SAFOV PET were between those of 3-and 5-min LAFOV PET. The smallest SUV max and SUV peak differences between SAFOV and LAFOV were found for 3-min LAFOV PET. Conclusion: LAFOV 89 Zr immuno-PET showed a lower SUV max and SUV peak than SAFOV because of lower image noise. LAFOV PET scan duration may be reduced at the expense of increasing image noise and bias in SUV metrics. Nevertheless, SUV peak showed only minimal bias when reducing scan duration from 30 to 10 min.

Current and Future Use of Long Axial Field-of-View Positron Emission Tomography/Computed Tomography Scanners in Clinical Oncology

“…In this immunoPET study, HER2-positive breast cancer patients were injected with 37 MBq [ 89 Zr]trastuzumab and scanned 4 days post injection on both SAFOV (Biograph mCT) and LAFOV (Biograph Vision Quadra) PET systems (Figure 1). Mohr and colleagues demonstrated that in an immunoPET study, the semiquantitative metrics (standardized uptake values (SUVs) and coefficient of variance) of a 30 min acquisition on a standard system was comparable with a 3 min acquisition on LAFOV, which means that a reduction of a factor of 10 would provide similar quality images (Figure 2) [22].…”

“…Breath-hold (BH) studies on SAFOV PET/CT have already shown promising results in mitigating such effects [23,24]. Nevertheless, the high sensitivity of LAFOV PET/CT makes breath-hold Mohr and colleagues demonstrated that in an immunoPET study, the semiquantitative metrics (standardized uptake values (SUVs) and coefficient of variance) of a 30 min acquisition on a standard system was comparable with a 3 min acquisition on LAFOV, which means that a reduction of a factor of 10 would provide similar quality images (Figure 2) [22].…”

“…Figure 3 shows the improved lesion definition of a solitary lung nodule in a 59-year-old patient with lung adenocarcinoma. © SNMMI [22]. acquisitions realistic.…”

First exploration of the on-treatment changes in tumor and organ uptake of a radiolabeled anti PD-L1 antibody during chemoradiotherapy in patients with non-small cell lung cancer using whole body PET

“…49 For 89 Zr-PET imaging, the use of this "total body PET-scanner" holds many advantages. We anticipate a lower noise-induced bias in the SUV peak measurements 50 , together with enhanced lesion detection sensitivity, shorter imaging time and/or reduction in radiation dose, which can be quite extensive for 89 Zr-labeled antibodies. The precision in imaging lung lesions, as in our trial, could be improved by applying ultrafast acquisition motion correction techniques 51 .…”

Image Quality and Quantitative PET Parameters of Low-Dose [18F]FDG PET in a Long Axial Field-of-View PET/CT Scanner

“…The extended axial field-of-view (aFOV) of these scanners, ranging between 64 to 200 cm, increases solid angle coverage for the detection of coincident events, providing a higher sensitivity and relevant improvements in the signal-to-noise ratio (SNR) compared to conventional PET scanners with a short axial field-of-view (SAFOV) [6,7]. Notably, the improved sensitivity is advantageous for examinations with low event statistics, such as PET imaging with radioisotopes that have low branching ratios such as Y-90 [8,9], allowing for post-therapeutic PET scans after trans-arterial radioembolization with Y-90 microspheres; immuno-PET imaging with long half-life radioisotopes such as Zr-89 [10,11], which allows the improved in vivo characterization of various tumors such as HER2-positive breast cancer [12]; and examinations with reduced doses of injected activity, contributing to a reduction in radiation exposure [13,14].…”