Regional MBF using [¹⁵O]H₂O and dynamic PET

Background

Positron emission tomography enables noninvasive quantification of myocardial perfusion. PET tracers that are used for estimation of blood flow include diffusible tracer [¹⁵O]H₂O and partially extracted tracers ⁸²Rb and [¹³N]ammonia.

Analysis methods used in literature

Measurement of perfusion with [¹⁵O]H₂O is based on the principle of exchange of inert gas between blood and tissues (Kety and Schmidt, 1945).

There exists several methods for estimation of myocardial perfusion, whichdiffer in the correction methods for spillover and partial volume effects.

Iida's [¹⁵O]H₂O bolus model

Iida et al. (1991, 1992) proposed a method in which the spillover and partial volume effects are taken into account in model parameters in both myocardial and left ventricular cavity (LV) regions.

Model equations are reviewed in TPCMOD0005.

Suggested analysis method

Our current suggestion (MET5817) is to use Iida's MBF model (Iida et al. 1991; Iida et al. 1992), as implemented in CarimasTurku™.

Iida's MBF model without CarimasTurku

fitmbf

Preparation of regional tissue TAC data

This is explained in detail elsewhere. In short: draw ROIs to left ventricular cavity (LV) and whole myocardium (WHOLE), and if needed, to other smaller myocardial structures as well. Calculate regional TACs from dynamic images, and calculate averages over planes and regions at least for LV and WHOLE. If you have regional TACs in old format (*.roi.kbq), convert those to DFT format using program nci2dft.

Calculation of MBF

Calculation can be done in Solaris terminal window or MS Windows command prompt window on either SUN or PC platform with fitmbf; the command line arguments can be seen from the previous link.

The units in the perfusion image are (ml blood)/(min * ml tissue).

If you have previously used older versions of this software (2.0 or less), please note that:

Only one study can be analyzed with one command. If α needs to be constrained to a basal study, it can be done with option -f
Existing result file with the same name is overwritten
Result files can be processed further, e.g. mean and s.d. from different subjects or differences between studies can be calculated before importing results to spreadsheet programs
fitmbf can optionally provide confidence limits and/or s.d. for the MBF, α and V_a

Older software version (2.0)

To use this, enter the command with version number: fitmbf_2_0_0. The results between this version and versions 2.1.* are similar inside three digits. The differences are in the usage:

Two or three studies may be calculated at one run, constraining α to the α estimate from the first study.

Result file format is different. If more than one study is analyzed at one run, all results are written in the same file.

If result file exists previously, it is not overwritten, but new results are appended to the end.

Even older software version(s)

Even older versions exist only on Solaris/SUN. Usage of those is not recommended.

Iida H, Rhodes CG, de Silva R, Yamamoto Y, Araujo LI, Maseri A, Jones T. Myocardial tissue fraction - correction for partial volume effects and measure of tissue viability. J Nucl Med 1991; 32:2169-2175.

Iida H, Rhodes CG, de Silva R, Araujo LI, Bloomfield P, Lammertsma AA, Jones T. Use of the left ventricular time-activity curve as a noninvasive input function in dynamic oxygen-15-water positron emission tomography. J Nucl Med 1992; 33:1669-1677.

Kajander S. MET5817: Sydämen diagnostinen [¹⁵]H₂O PET tutkimus. Turku PET Centre Quality Documents, 2009.

Kety SS, Schmidt CF. The determination of cerebral blood flow in man by the use of nitrous oxide in low concentrations. Am J Physiol. 1945; 143: 53-66.

Oikonen V. Model equations for myocardial perfusion studies with [¹⁵O]H₂O PET. TPCMOD0005

Watabe H, Jino H, Kawachi N, Teramoto N, Hayashi T, Ohta Y, Iida H. Parametric imaging of myocardial blood flow with ¹⁵O-water and PET using the basis function method. J. Nucl. Med. 2005; 46: 1219-1224.

Regional MBF using [15O]H2O and dynamic PET