Minimum Dose, Maximum Speed
One of the key trends in nuclear medicine has been the ever-increasing demand for faster myocardial perfusion imaging. Historically, image quality has been limited by the number of detected photons.
To achieve the desired image quality, routine cardiac SPECT studies can take up to 16 minutes, limiting the number of patient scans and, most importantly, exposing patients to unnecessary radiation. With these challenges in mind, Siemens Molecular Imaging, developed IQ•SPECT, a unique solution to maximize detected counts from the heart without truncation and offer fast cardiac imaging at the lowest possible dose, while maintaining high image quality.
Symbia Evo with IQ•SPECT is the only general-purpose system that enables four-minute ultra-fast cardiac imaging without sacrificing image quality. This exclusive feature is also available on Siemens hybrid SPECT systems.
Its unique collimator design, cardio-centric image acquisition and advanced reconstruction technology acquires four-times more counts than conventional methods for high quality images independent of age, body shape or size. With IQ•SPECT, physicians can perform a myocardial perfusion imaging study in approximately 4 minutes using the standard dose, 8 minutes using half the standard dose or 16 minutes using one-quarter of the standard dose.
With its SMARTZOOM collimators, modified cardio-centric acquisition and special reconstruction methods, IQ•SPECT is the solution for fast cardiac imaging using half the dose with twice the speed.
Siemens SMARTZOOM collimators employ the magnifying properties of a cone-beam collimator near the center of the field of view and eliminating truncation at the edges of the field of view similar to a parallel-hole collimator. The unique position and shape of each hole in the collimator, also referred to as a vector map, is measured in the factory at Siemens and stored with the collimator to be used during reconstruction. The result is an increase of up to four-times more sensitivity.
IQ•SPECT positions the heart in the center of the collimator field of view and positions the detectors at a 28 cm radius for the cardio-centric orbit. IQ•SPECT uses the flexibility of the Symbia™ gantry to position each detector at an optimal distance to maximize sensitivity gain and minimize feelings of claustrophobia.
The advanced IQ•SPECT reconstruction method is a proprietary implementation of a conjugate-gradient iterative reconstruction algorithm. The algorithm is optimized to accurately reflect the measured geometry of the SMARTZOOM collimators and the cardio-centric orbit of the detectors. A 3D measurement of gantry deflection allows correction of gantry motion based image distortions. Measurements of hole size, shape, and pointing direction for all 48,000 holes in the SMARTZOOM collimator ensure accurate image reconstruction.