Phantom Validation of Tc-99m Absolute Quantification in a SPECT/CT Commercial Device

Abstract

Aim. Similar to PET, absolute quantitative imaging is becoming available in commercial SPECT/CT devices. This study's goal was to assess quantitative accuracy of activity recovery as a function of image reconstruction parameters and count statistics in a variety of phantoms. Materials and Methods. We performed quantitative 99mTc-SPECT/CT acquisitions (Siemens Symbia Intevo, Erlangen, Germany) of a uniform cylindrical, NEMA/IEC, and an anthropomorphic abdominal phantom. Background activity concentrations tested ranged: 2–80 kBq/mL. SPECT acquisitions used 120 projections (20 s/projection). Reconstructions were performed with the proprietary iterative conjugate gradient algorithm. NEMA phantom reconstructions were obtained as a function of the iteration number (range: 4–48). Recovery coefficients, hot contrast, relative lung error (NEMA phantom), and image noise were assessed. Results. In all cases, absolute activity and activity concentration were measured within 10% of the expected value. Recovery coefficients and hot contrast in hot inserts did not vary appreciably with count statistics. RC converged at 16 iterations for insert size > 22 mm. Relative lung errors were comparable to PET levels indicating the efficient integration of attenuation and scatter corrections with adequate detector modeling. Conclusions. The tested device provided accurate activity recovery within 10% of correct values; these performances are comparable to current generation PET/CT systems.

SPECT/CT activity quantification in 99mTc-MAA acquisitions.

“…We attributed this underestimation to some activity flow towards the abdominal regions outside the SPECT field of view. The results obtained with patient acquisitions were in accordance with those presented in a similar work by Gnesin S. et al in [7]. In summary with this study we verified that our scanner may quantify 99m Tc SPECT/CT acquisitions with a good accuracy using a simple calibration method.…”

Towards standardization of absolute SPECT/CT quantification: a multi-center and multi-vendor phantom study

“…This study is a considerable step towards standardization of absolute SPECT quantification by investigating the quantitative accuracy of different SPECT/CT systems. The quantitative accuracy of individual SPECT-CT systems was assessed earlier for the GE Discovery NM/CT 670 system [5], the Siemens Symbia Intevo system [44] and the Hermes SUV SPECT quantitative reconstruction algorithm [36]. Although an earlier study by Seret et al [32] also compared the quantitative capabilities of four SPECT/CT cameras, our study included the current state-of-the-art quantitative SPECT/CT systems that enable absolute quantification that were not available at that time.…”

Quantitative accuracy of 177Lu SPECT imaging for molecular radiotherapy

“…The image noise for both reference geometries was evaluated by means of the coefficient of variation ( COV ), defined as the ratio between the standard deviation ( s ) and the average ( M ) of voxel counts inside the VOIs considered [ 21 , 28 ]. In particular, for Hp twelve 16 ml spherical VOIs (left superior corner of Fig 1A ) were drawn at a distance of 15 mm from the edge of the phantom, and for each VOI w ( w = 1, 2, …, 12, see inset in left superior corner of Fig 1A ) the COV was evaluated as reported in Eq ( 2 ): …”