PMOD CRV file format

CRV is a text-based file format for PET time-activity curve (TAC) data of the PMOD software, which is also supported by TPCCLIB software.

Data is organized in columns, separated by a single tabulator character. Thus, PMOD CRV files are in TSV format. CRV file contain a single title line, followed by numerical data. Decimal point should be used as decimal separator, although both decimal point and comma are supported by TPCCLIB software.

The title line specifies the column names. Time units (minutes, seconds, hours) are specified in square brackets immediately after the name of the first column title, and TAC value units are similarly given immediately after the name of the second column.

File name extension should be .crv. By convention, extensions .bld and .tac are also used for tissue and blood TAC data, respectively.

TAC data with frame start and end times

PET and ABSS radioactivity is measured during a time frame, and each sample point in the TAC represents the average radioactivity concentration during that frame. Commonly the TAC data is saved with only the mid frame time, but further calculations can be done with better precision if both frame start and end times are stored in the TAC file. In PMOD CRV the frame start and end times can be saved as the two first columns, with titles start and end, respectively. The time and concentration units, if available, are given in these titles, respectively.

As an example, the regional TACs of cerebellum and right and left striatum in a [11C]Raclopride PET study are given below in PMOD CRV (TAC) format:

start[minutes]	end[kBq/cc]	Cerebellum	striatum dx	striatum sin
0.00	1.00	3.193e+00	3.624e+00	3.506e+00
1.00	2.00	5.513e+00	6.538e+00	6.119e+00
2.00	3.00	5.402e+00	7.411e+00	8.394e+00
3.00	4.00	5.025e+00	7.397e+00	7.793e+00
4.00	5.00	5.330e+00	8.448e+00	7.867e+00
5.00	6.00	5.170e+00	8.037e+00	9.793e+00
6.00	7.00	4.618e+00	9.724e+00	8.994e+00
7.00	8.00	4.595e+00	8.382e+00	9.098e+00
8.00	9.00	4.211e+00	9.623e+00	8.962e+00
9.00	10.0	4.386e+00	1.005e+01	8.510e+00
10.0	11.0	4.259e+00	8.642e+00	9.859e+00
11.0	12.0	4.248e+00	9.874e+00	1.060e+01
12.0	13.0	4.002e+00	1.015e+01	9.235e+00
13.0	14.0	4.005e+00	8.660e+00	9.003e+00
14.0	15.0	3.868e+00	9.943e+00	8.138e+00
15.0	17.0	3.814e+00	9.683e+00	8.814e+00
17.0	19.0	3.576e+00	9.297e+00	8.926e+00
19.0	21.0	3.589e+00	9.755e+00	9.483e+00
21.0	23.0	3.363e+00	9.456e+00	9.612e+00
23.0	25.0	3.345e+00	8.644e+00	1.021e+01
25.0	27.0	3.300e+00	9.341e+00	9.224e+00
27.0	29.0	3.116e+00	8.931e+00	8.699e+00
29.0	34.0	3.333e+00	9.569e+00	8.775e+00
34.0	39.0	3.145e+00	9.596e+00	8.943e+00
39.0	44.0	3.088e+00	8.813e+00	8.892e+00
44.0	49.0	2.925e+00	8.509e+00	8.976e+00
49.0	54.0	2.731e+00	8.256e+00	7.552e+00
54.0	60.0	2.883e+00	8.593e+00	8.372e+00

TAC data with sample time

Blood and plasma TACs measured with manual blood sampling have only a single time column. ABSS blood data is usually collected with very short frame durations, and therefore that is also stored with a single time column, representing the mid times of frames. PET image-derived input data should be stored with frame start and end times.

The title of the sample time column in PMOD CRV format is time, immediately followed by the units in square brackets. The following column has title plasma, blood, or parent-fraction, immediately followed by the units of the concentrations in square brackets, or [1/1] in case of unitless fractions. The file could also include more concentration columns with appropriate column titles, but programs processing input data often assume that only one concentration column is present.

As an example, the plasma TAC, based on arterialized venous blood sampling, in a [18F]FDG PET study is given below in PMOD CRV (BLD) format:

time[minutes]	plasma[kBq/cc]
0.333	3.2220e+00
0.850	3.3467e+01
1.233	1.9928e+01
1.667	1.6322e+01
2.050	1.4923e+01
3.250	1.2470e+01
5.367	9.9100e+00
9.117	6.6850e+00
19.000	3.0710e+00
24.367	2.2770e+00
29.083	1.7530e+00
34.017	1.3990e+00
49.300	7.2500e-01
69.100	4.5500e-01
82.967	3.5400e-01

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Updated at: 2019-11-21
Created at: 2019-11-21
Written by: Vesa Oikonen