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Read a Philips MRI Physiological Log File

Source: R/read_philips_physlog.R
read_philips_physlog.Rd

Reads a Philips PMU physiological log (.log) file recorded alongside an MRI acquisition and returns a structured object containing the signal matrix, event markers, and recording metadata. Supports all Philips PMU hardware variants via the system preset.

Usage

read_philips_physlog(
  path,
  system = c("wBTU", "wired", "custom"),
  sfreq = NULL,
  channels = NULL,
  skipprep = FALSE
)

Arguments

path

Character. Path to the Philips .log file.

system

Philips PMU hardware preset. One of:

"wBTU" (default)

Wireless VCG system, 496 Hz. 10-channel layout: v1raw, v2raw, v1, v2, ppu, resp, gx, gy, gz, mark. Used with the Philips Achieva/Ingenia dStream wireless body telemetry unit.

"wired"

Older wired ECG system, 500 Hz. Fewer channels (no accelerometer); layout read from file header.

"custom"

Supply sfreq explicitly.

sfreq

Numeric or NULL. Sampling frequency in Hz. Overrides the system preset when supplied. Required when system = "custom".

channels

Character vector or NULL. Channel names to return. NULL (default) returns all channels. "none" returns no signal data (markers only).

skipprep

Logical. If TRUE, skip samples recorded before the blank # line that marks the end of the preparation phase. Default FALSE.

Value

A list of class mrpheus_physlog with components:

C

Integer matrix (samples × channels). Column order matches the file header.

M

Two-column integer matrix: marker (bit-encoded value) and index (1-based sample number) for every non-zero marker.

I

Named list of 1-based sample index vectors for each event type: VcgOnset, PpuOnset, TriggerResp, Measurement, ScannerStart, ScannerStop, TriggerExt, Calibration, RefTriggerVcg.

HDR

List of header metadata: ID, DATETIME, STATS, DockableTable, COLUMN_NAMES, system, sfreq.

path

Character. Resolved path to the source file.

Details

Bit-encoded marker values:

0x0001  ECG trigger       0x0002  PPU trigger      0x0004  respiration
0x0008  slice onset       0x0010  scanner start    0x0020  scanner stop
0x0040  external trigger  0x0080  calibration      0x8000  ref ECG trigger

Use the scanner-stop marker (more reliable than start) to time-lock data:

stopidx  <- tail(data$I$ScannerStop, 1) - enddelay
startidx <- stopidx - round(n_vols * TR * data$HDR$sfreq)
epoch    <- data$C[startidx:stopidx, ]

See also

detect_qrs(), compute_hr_signal()

Examples

if (FALSE) { # \dontrun{
# Philips Achieva/Ingenia with wireless VCG (default)
rec <- read_philips_physlog("sub-01_ses-01_physlog.log")
rec

# Older wired scanner
rec <- read_philips_physlog("sub-01_physlog.log", system = "wired")

# Custom sampling rate
rec <- read_philips_physlog("sub-01_physlog.log", system = "custom", sfreq = 400)

# ECG channels only
rec <- read_philips_physlog("sub-01_physlog.log", channels = c("v1raw", "v2raw"))
} # }