IQ•SPECTThe art of minimizing dose while maximizing speed

A key trend in nuclear medicine is the ever-increasing demand for faster MPI exams. IQ•SPECT™ is a cardiac imaging solution that uses a combination of converging collimators, modified cardio-centric acquisition, and special reconstruction methods to deliver ultrafast cardiac imaging that is four times faster than conventional SPECT acquisition.

Siemens IQ•SPECT is the only technology today that performs ultra-fast cardiac imaging with a general purpose camera. Its unique collimator design, cardiocentric 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 cardiocentric 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.
 

Conventional scanners use parallel-hole collimators and orbits about the center of the gantry. Detectors rotate in close proximity to the patient, often causing feelings of claustrophobia.
 

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.

Combined with advanced reconstruction, this method allows for a selection of optimized protocol options:

• 4 min, standard dose
• 8 min, half dose
• 16 min, quarter dose

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.