Preliminary pinhole SPECT reconstruction results from the NaI detectorImages are displayed as MIP (maximum-intensity-re-projections) animations

Please use slide show mode to see the animation

Reconstruction cineProjection cine

Fig.25 Misure al Johns Hopkins, Giugno 2006. Topo con MDP (si fissa nelle ossa)

Preliminary pinhole SPECT reconstruction results from the CsI detectorImages are displayed as MIP (maximum-intensity-re-projections) animations

2 point sources APOE mouse (kidneys shown)

Flood imageSample projectio

nimage

Fig. 28 APOE mice

APPROACH

Transgenic mouse modelAPOE-/- miceSpontaneous growth of atherosclerotic plaques accelerated by fatty diet

Imaging agent99mTc-HYNIC-Annexin-V Binds to apoptotic cells

Imaging techniquesHigh-resolution pinhole SPECT

ApomateTM: Trade name for Hynic Annexin V, North

American Scientific, Inc.

20 weeks

Plaque?

ApoE-/- mice

99mTc-Annexin-V SPECT images

Excised aorta from 37 weeks mouse

Photo autoradiography

0.9 mm 99mTc capillars, 1.3 mm step

1.3 mm

FWHM1.05 mm

1.1 capillars, 1.5 mm step

0.9 capillars, 1.3 mm step

Spatial resolution: 0.55 mm !!

0.38 mm W pinhole, M=3.3, CsI:Tl array 1 mm step

Other simulations done for the CsI(Na) option evaluation….

CsI(Na) is an interesting option. Unfortunately arrays with pixels smaller than 0.8 mm pitch cannot be built. It is igroscopic, so a window is needed (with spatial resolution degradation) or the integral line layout has to be used.

Careful evaluation of the different options has to be done validating the simulations by measurements first.

Then, decision to be taken on the SNR evaluation base looking at the specific application

Tradeoff

spatial resolution/efficiency/

energy resolution

summarizing

FOV

sensitivity

Rt

Scaling down (100 mm , 1 mm pitch ---> 50 mm 0.5 mm pitch)

Choosing the right M to get the best compromise between FOV, Rt and sensitivity

For example, to improve Rt, just sacrify FOV getting at the same time better sensitivity

Rt=0.1mm

FOV~5mm

Trading off…