Comparison of Scintimammography and Dedicated Emission Mammotomography Martin P. Tornai, Caryl N. Brzymialkiewicz, Spencer J. Cutler, Priti Madhav Multi-Modality Imaging Laboratory Department of Radiology Department of Biomedical Engineering Duke University Medical Center, Durham, NC, USA Supported by NIH Grant RO1-CA96821 and DAMD 17-03-1-0558

Overview Develop a “universal” breast phantom for emission and/or transmission imaging Needs to be compressible for uncompressed and partial compression imaging comparisons Needs to accommodate inserted lesions Needs to have physical attributes similar to human torso Make direct comparison of uncompressed breast SPECT and compressed scintimammography Develop and compare various fillable lesion sizes Compare different activity concentrations

Solid State Imaging Detector Detector CdZnTe Density 5.78 g/cm3 Effective Z 49 Elements 64 x 80 Crystal Dimensions 2.3 x 2.3 x 5 mm3 Pixel Size 2.5 x 2.5 mm2 FOV 16 x 20 cm2 Sensitivity 38 cts/sec/MBq Uniformity (post corr) < ±4% Energy Resolution 6.1% @ 140 keV 20.0 cm 16.0 cm 6.6 cm LumaGEM™ 3200-S (Gamma Medica Inc.)

Prototype Emission Mammotomograph Anthropomorphic torso and breast phantoms (Radiology Support Devices, Inc.) Integrated Gamma Camera (Gamma Medica, Inc.) Polar Tilt,  ROR Azimuth,  Radius of Rotation control (Newport Corp., Sanyo-Denki) Rotation stage and goniometer (Newport Corp.)

Compressible Breast Phantom & Chest Plate Fill port 3 cm f insertion port Fillable Volume: ~700 mL Nipple-Chest: 9 cm Medial-Lateral: 12 cm Superior-Inferior: 13 cm “Skin” thickness: 0.16 cm (Radiology Support Devices, Inc.)

Compressible Breast Phantom & Lesions Digital X-ray image Stems: 1.6 mm OD x 4.5 cm polyethylene 70 500 140 300 Lesions Volume “Diameter” (microL) (mm) 40 +/- 0.15 4.2 70 +/- 0.15 5.1 140 +/- 0.15 6.4 300 +/- 0.30 8.2 500 +/- 0.30 9.8 40 140 140 (Harvard Apparatus)

Scintimammography Acquisition Parameters Lesion Concentration 40 microCi / mL 20X clinical ! Lesion : Background Inf., 12 : 1, 7 : 1, 3 : 1 View Lateral (single view) Compression 12 cm, 9 cm, 6 cm Acquisition Time 10 min (equivalent)

Breast Compression 4 cm 12 cm 9 cm 6 cm Cranio-Caudal Lateral

Scintimammography (Planar) Projections Compression Thickness 9cm 7 : 1 9cm 12 : 1 9cm 3 : 1 12 cm 9 cm 6 cm 12 : 1 7 : 1 Leaky Phantom 3 : 1

Scintimammography: Effects of Compression 12 : 1 Concentration Ratio

Scintimammography: Effects of Activity Concentration 6 cm Compression

SPECT Acquisition Parameters 20X clinical ! Lesion Concentration 40 microCi / mL Lesion : Background Ratios Inf., 12 : 1, 7 : 1, 3 : 1 Mammotomography (q = 0 – 360) Orbits: Vertical Axis of Rotation (VAOR) ROR = 6.6 cm, f = 0 deg Tilted Parallel Beam (TPB) ROR = 5.2 cm, f = 45 deg 3 Lobed Sinusoid on Hemisphere (ProjSine) ROR = 2.8 – 5.2 cm, f = 15 – 45 deg Angular Increment : 2.8 deg Acquisition Time : 10 min (equivalent) Details about orbits and sampling on POSTER # M2-269

Mammotomography Orbits VAOR TPB45 ProjSine 0o 30o 60o 90o Camera Tilt () Details about orbits and sampling on POSTER # M2-269

Mammotomography Reconstructions 12 : 1 Concentration ProjSine Data Transverse Sagittal Maximum Intensity Projection (MIP) OSEM reconstruction with 5 iterations, 8 subsets, calculated attenuation correction, 3D Hann filtration with fc = 0.8*Nyquist

Mammotomography MIPs 300 uL 500 uL 40 uL 70 uL 140 uL VAOR TPB45 ProjSine 12 : 1 7 : 1 3 : 1

SPECT SNR & Contrast 12 : 1 Concentration Data ROI data from OSEM reconstruction with 3 iterations, 8 subsets, calculated attenuation correction, 3D Hann filtration with fc = 0.8*Nyquist

SPECT & Scintimammography SNR & Contrast

Conclusions Developed a compressible breast+chest phantom useful for comparative emission breast imaging with physical limitations more consistent with a human torso Measured various lesion sizes, locations (esp. near chest wall), and activity concentrations relative to backgrounds Compared compressed breast, planar scintimammography with uncompressed breast SPECT mammotomography Scintimammography has limited viewable breast volume towards the anterior chest wall Under a wide range of “low noise” measurement conditions: More lesions, lesion sizes, and (3D) lesion locations can be detected (and thus quantitated) with dedicated emission mammotomography than with compressed breast scintimammography

Multi-Modality Imaging Lab