Presentation on theme: "STIR – 1 Digital Phantom Project"— Presentation transcript:
1STIR – 1 Digital Phantom Project Kohsuke Kudo, Soren Christensen, Makoto Sasaki, and Leif Ostergaard
2BackgroundA variety of post-processing programs and algorithms for CT perfusion and dynamic susceptibility contrast (DSC) MR perfusion are available from CT or MR manufacturers, third-party workstation vendors, and academic groups.However, the accuracy and reliability of these programs have not been subject to standardized quality control.
3PurposeTo design a digital phantom data set both for CT perfusion and DSC MR perfusion based on widely accepted tracer kinetic theory in which a range of true values of cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and tracer arrival delay are known.To evaluate the accuracy of post-processing programs using this digital phantom.
4Methods – AIF/VOFArterial input function (AIF) was generated using Gamma-variate function.Venous output function (VOF) was generated by deconvoluting AIF and Exponential R(t).
5Methods – AIF/VOFConcentration time curves, C(t), were converted to signal time curves, S(t), for MR.
6Methods – Tissue Curves Tissue curves were generated by deconvoluting AIF and R(t). Three kinds of R(t) were used, Exponential, Linear, and Box.
7Methods – Tissue Curves Tissue curves were also converted to signal curves for MR.
8Methods – Data Structure The phantom data set had 7 slices and 50 phases (total 350 images). Curves for AIF/VOF were embedded in slice #1. Tissue curves were embedded in slice #2 to #7, with different R(t) and CBV.Slice #1AIF/VOFSlice #2, 3R(t) = Exp.CBV = 2, 4 %Slice #4, 5R(t) = LinearSlice #6, 7R(t) = Box
9Methods – AIF/VOF Image -3-2-1Delay (s) = 0+1+2+3AIFs VOFAIF without delay and VOF were used.
10Methods – Tissue Images -3-2-1Delay (s) = 0+1+2+3MTT (s) =CBF (mL/100g/min) = (CBV = 2%)(CBV = 4%)
11Method – True Values R(t): Exponential, Linear, and Box Delay: -3, -2, -1, +0, +1, +2, and +3 secCBV: 2 and 4%CBF: 5, 10, 15, 20, 25, 30, and 35 mL/100g/min10, 20, 30, 40, 50, 60, and 70 mL/100g/minMTT: 3.4, 4, 4.8, 6, 8, 12, and 24 sec
22Summary CT Perfusion Commercial Software GE(CTP3) : accurate but delay sensitiveGE(CTP4) : sensitive to negative delayHitachi(IF) : CBV/MTT are delay sensitivePhilips(SVD) : delay sensitiveSiemens(LMS) : could not be analyzedToshiba(bMTF) : delay sensitiveToshiba(SVD+) : could not be analyzedAcademic SoftwarePMA(sSVD) : delay sensitivePMA(bSVD) : delay insensitive and accurate
23Summary MR Perfusion Commercial Software GE(FM) : delay insensitive but not accurateHitachi(FM) : delay insensitive but not accuratePhilips(FM) : delay insensitive but not accurateSiemens(SVD) : delay sensitiveAcademic SoftwareEPITHET(SVD) : only TmaxPenguin(sSVD) : delay sensitivePenguin(oSVD) : delay insensitiveRapid(sSVD) : delay sensitiveRapid(cSVD) : delay insensitive and accuratePMA(sSVD) : delay sensitivePMA(bSVD) : delay insensitive and accurate
24Newer Version of Phantom All the curves are embedded in “real” brain image, because some programs require anatomical configuration.AIFVOFOnly “positive delays” are used, because negative delays are not realistic if we choose proper AIF.Five CBV values are embedded to see linearity of CBV.Noise was added stronger to resemble clinical data.
25Preliminary Results for CT CBFCBVMTTGECTP3GECTP4HitachiIFPhilipsSVDSiemensLLMSToshibabMTFToshibaSVD+PMAsSVDPMAbSVD
26ConclusionThe digital phantom can be used for the evaluation of accuracy and reliability of perfusion software packages, and also used for the certification and standardized quality control.