This page is obsolete: please read the new pages about image file formats and tools for image data.

PET image data

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HRRT produces Interfile format images, which can be converted to ECAT 7 format using if2ecat program (PC/Windows XP) provided by the scanner manufacturer, or an in-house program if2e7 by Roman Krais. ECAT 7 format images are copied to PETO system. More information on HRRT and also other scanners.


ECAT HR+ produces ECAT 7.x format files. HR+ image data is copied to the PETO system by the imaging laboratory personnel.

GE Advance

GE Advance image data is extracted from the GE database, converted to ECAT 6.3 format, and copied to the PETO system by the imaging laboratory personnel. Images can also be extracted in PET DICOM format and converted to ECAT 7 format if necessary (contact Chunlei Han).

GE Discovery STE VCT

GE Discovery STE VCT (Teräs et al., 2007) stores the PET and CT images in DICOM format, which can be converted to ECAT 7 format if necessary within-house program dicom2ecat (please contact Harri Merisaari).

Inveon small-animal PET/CT

Siemens Inveon small-animal PET/CT is located in Turku Center for Disease Modeling. Image data is stored in Concorde/microPET format. Images can be sent to PETO system. A very primitive tool for Inveon to ECAT 7 image format conversion is available.

Image file formats


Currently most analysis programs can use PET image data in ECAT 7 format, which is the format that ECAT HR+ produces. ECAT 7 format definition is in ECAT Software Operating Instructions Version 7.2, Appendix B; PDF in intranet.

During a long transitional stage most programs will be able to read also ECAT 6.3 format, which is the format of our first PET scanner, ECAT 931. This scanner was put out of operation in the end of April 2005. ECAT 6.3 format for images is defined in Siemens manual (Operating Instructions ECAT Scanner Software).

Tools for conversion between ECAT formats are available, and tools for conversion between ECAT 7 and PET DICOM are under development/testing.

Polar map

A variant of ECAT 7 polar map format will be used in Turku PET Centre for storing and modeling myocardial PET data. Polar maps will be constructed with Carimas.

Dynamic and parametric polar map can be converted to/from DFT file using programs pm2dft and dft2pm.

Analyze 7.5

A variant of Analyze 7.5 image format is partially supported. A few image processing and analysis programs are able to read and write this format. Tools for conversion between ECAT and Analyze formats are available.


Carimas can process DICOM format images, as well as new C#/.NET software. DICOM images can also be converted to ECAT 7 format, if necessary, within-house program dicom2ecat (please contact Harri Merisaari).

Inveon/Concorde MicroPET

Siemens Inveon PET images consists of two files, *.img and *.img.hdr. These can be read and processed with Amide and coming version of Carimas. A very primitive tool for Concorde/microPET to ECAT 7 format conversion is also available.

Unit of radioactivity

By default, the radioactivity concentrations in PET images are corrected for physical decay to the injection time. Radioactivity concentrations in ECAT 6.3 format images are calibrated to units kBq/ml (ml=cc) and in ECAT 7.x format images to units Bq/cc, but there may be exceptions; when necessary, check or set the units using program ecatunit. Correction for partial volume effect, is available in Turku PET Centre (contact Harri Merisaari).

PET data may contain patient names!

Please note that images and sinograms in DICOM or ECAT 6.3/7 format may contain the name of subject. Transfer of PET images or sinograms using any media outside PET Centre and University Hospital is strictly forbidden, unless the name is first removed; see Patient privacy protection.

Working with image data:

Extract part of image:

Retrieving information on ECAT files:

Retrieving and editing information on Analyze 7.5 files:

Image filtering:

Converting ECAT files to binary flat files and back:

Converting between ECAT and DICOM formats


Teräs M, Tolvanen T, Johansson JJ, Williams JJ, Knuuti J. Performance of the new generation of whole-body PET/CT scanners: Discovery STE and Discovery VCT. Eur J Nucl Med Mol Imaging 2007; 34: 1683-1692.

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