Standardized Expression of ¹⁸F-NAV4694 and ¹¹C-PiB β-Amyloid PET Results with the Centiloid Scale

Abstract

A common quantitative output value for PET measures of β-amyloid (Aβ) binding across tracers and methods would allow better comparison of data across sites and application of universal diagnostic and prognostic values. A method has recently been developed that generates a unit of measurement called the centiloid. We applied this method to 2-[2-18 F-fluoro-6-(methylamino)-3-pyridinyl]-1-benzofuran-5-ol ( 18 F-NAV4694) and 11 C-Pittsburgh compound B ( 11 C-PiB) Aβ images to derive the scaling factor required to express tracer binding in centiloids. Methods: Fifty-five participants, including 10 young controls (33 ± 7 y old), underwent both 11 C-PiB and 18 F-NAV4694 imaging no more than 3 mo apart, with the images acquired 50-70 min after tracer injection. The images were spatially normalized and analyzed using the standard centiloid method and regions (cortex and whole-cerebellum reference) downloaded from the Global Alzheimer Association Interactive Network website. Results: SUV ratios (SUVRs) showed a strong correlation in tracer binding ( 18 F-NAV4694 SUVR 5 1.09 · 11 C-PiB SUVR -0.08, R 2 5 0.99). The equation to convert 18 F-NAV4694 to centiloids [100 · ( 18 F-NAV4694 SUVR -1.028)/1.174] was similar to a published equation for 11 C-PiB [100 · ( 11 C-PiB SUVR -1.009)/1.067]. In the young controls, the variance ratio ( 18 F-NAV4694 centiloid SD divided by 11 C-PiB centiloid SD) was 0.85. Conclusion: The results for both 11 C-PiB and 18 F-NAV4694 can now be expressed in centiloids, an important step that should allow better clinical and research use of Aβ imaging. The standard centiloid method also showed that 18 F-NAV4694 has slightly higher Aβ binding and lower variance than 11 C-PiB, important properties for detecting early Aβ deposition and change over time.

Comparison of Pittsburgh compound B and florbetapir in cross‐sectional and longitudinal studies

“…An intertracer correlation of R 2 = 0.99 was observed between PiB and [ 18 F]‐NAV4694, and R 2 = 0.96 was observed between PiB and [ 18 F]‐florbetaben. The variance of amyloid burden measurements in young controls was SD = 3.7 for [ 18 F]‐NAV4694 and SD = 6.81 for [ 18 F]‐florbetaben [14,15]. Recently, Navitsky et al [16] reported an SD = 12.07 for florbetapir, and here, we observed an SD = 14.2 for the raw florbetapir SUVr‐derived Centiloid measurements; however, when the RSF PVC technique was used in the quantification procedure, the variance was substantially reduced (SD = 5.4).…”

“…These results are in agreement with ours. The Centiloid conversion and comparison to PiB has been reported for two other 18 F‐tracers, that is, [ 18 F]‐NAV4694 [14] and [ 18 F]‐florbetaben [15]. An intertracer correlation of R 2 = 0.99 was observed between PiB and [ 18 F]‐NAV4694, and R 2 = 0.96 was observed between PiB and [ 18 F]‐florbetaben.…”

“…These results are in agreement with ours. The Centiloid conversion and comparison to PiB has been reported for two other 18 F-tracers, that is, [ 18 F]-NAV4694 [14] and [ 18 F]-florbetaben [15]. An intertracer correlation of [14,15].…”

“…The Centiloid conversion and comparison to PiB has been reported for two other 18 F-tracers, that is, [ 18 F]-NAV4694 [14] and [ 18 F]-florbetaben [15]. An intertracer correlation of [14,15]. Recently, Navitsky et al [16] reported an SD 5 12.07 for florbetapir, and here, we observed an SD 5 14.2 for the raw florbetapir SUVr-derived Centiloid measurements; however, when the RSF PVC technique was used in the quantification procedure, the variance was substantially reduced (SD 5 5.4).…”

PET Amyloid Analyses

“…describe application of the centiloid methodology for scaling and analysis of studies performed with 18 F-NAV4694 for characterizing cerebral amyloid deposition in clinical research (1). This is one of several evolving approaches to analysis of amyloidtargeting radiotracers that have emerged recently.…”