Compute Centiloid Value — compute_centiloid • admiralneuro

Computes centiloid values based on amyloid PET tracer, SUVR value and pipeline, and reference region. Also allows for custom formula parameters.

Usage

compute_centiloid(
  tracer,
  pipeline,
  ref_region,
  suvr,
  custom_slope = NULL,
  custom_intercept = NULL
)

Arguments

tracer

Amyloid PET tracer

A character string is expected. If custom_slope and custom_intercept are specified, this parameter is ignored. See Details section for accepted values in combination with pipeline and ref_region.

pipeline

SUVR pipeline

ref_region

Reference region

suvr

SUVR value

A numeric value is expected.

custom_slope

Optional slope parameter for custom centiloid calculation formula

A numeric value is expected when provided. When custom_slope is specified (along with custom_intercept), this overrides the standard formula parameters tracer, pipeline, and ref_region. Default is NULL.

custom_intercept

Optional intercept parameter for custom centiloid calculation formula

A numeric value is expected when provided. When custom_intercept is specified (along with custom_slope), this overrides the standard formula parameters tracer, pipeline, and ref_region. Default is NULL.

Value

A numeric centiloid value

Details

The centiloid scale is a standardized quantitative measure for amyloid PET imaging that allows comparison between different tracers and analysis methods. This function converts SUVR values to the centiloid scale based on published conversion equations for specific tracer, pipeline, and reference region combinations.

Centiloid is calculated as:

$$Centiloid = slope \times SUVR + intercept$$

where slope and intercept are formula parameters. If custom_slope and custom_intercept are not specified, this function uses pre-defined slope and intercept based on the user's selections of tracer, pipeline, and reference region.

The following combinations of tracer, pipeline, reference region, slope, and intercept are supported:

tracer	pipeline	ref_region	slope	intercept
18F-Florbetapir	AVID FBP SUVR PIPELINE¹	Whole Cerebellum	183.00	-177.00
18F-Florbetapir	BERKELEY FBP SUVR PIPELINE²	Whole Cerebellum	188.22	-189.16
18F-Florbetaben	BERKELEY FBB SUVR PIPELINE³	Whole Cerebellum	157.15	-151.87

The equation used for the conversion is based on the following references:

¹ Navitsky, et. al., 2018 ² ADNI Florbetapir PET Methods, login required ³ ADNI Florbetaben PET Methods, login required

Alternatively, the user can override the pre-selection by specifying custom_slope and custom_intercept instead. If custom_slope and custom_intercept are specified, tracer, pipeline and ref_region are ignored.

If a matching combination of tracer, pipeline and reference region is not specified and custom_slope and custom_intercept are not specified, a warning is issued and NA_real_ is returned.

Examples

# Using standard parameters
compute_centiloid(
  tracer = "18F-Florbetapir",
  pipeline = "AVID FBP SUVR PIPELINE",
  ref_region = "Whole Cerebellum",
  suvr = 1.25
)
#> [1] 51.75

# Using custom parameters
compute_centiloid(
  tracer = "MyTracer",
  pipeline = "MyPipeline",
  ref_region = "MyRegion",
  suvr = 1.25,
  custom_slope = 193,
  custom_intercept = -187
)
#> [1] 54.25