"The introduction of the tomographic technique and the implementation of Technegas as a novel ventilation agent facilitated imaging of pulmonary embolism in comparison with planar imaging and particularly in COPD patients together with the new interpretation criteria."

"Although not as available as chest X-ray, V/P SPECT is a feasible alternative, especially because the introduction of SPECT and new ventilation tracers (i.e. Technegas) has lowered the number of non-diagnostic studies to <3%, even in the presence of obstructive lung disease."

"The best widely available agent for ventilation is 99mTc-Technegas, an aerosol of carbon nanoparticles (5-200 nm) generated in a high temperature furnace (Technegas Generator, Cyclomedica). Because of the very small particle size, this agent is distributed in the lungs almost like a gas and deposited in alveoli by diffusion, where they remain stable, thus providing the best possible images for ventilation SPECT."

"V/Q scintigraphy is a valuable functional imaging biomarker in relation to several aspects of COPD. Disturbances in the distribution of ventilation and perfusion, which are pertinent to the pathophysiology of COPD, are directly visualized, particularly when using inert gases or Technegas as ventilation tracers while performing the scintigraphy as SPECT."

"3D ventilation/perfusion SPECT imaging procedures have been used to help diagnosis. COPD patients have also been evaluated using Technegas (99mTc-labelled carbon particles). Technegas has the potential to provide valuable information for the diagnosis of COPD as it has been demonstrated to correlate positively with spirometric lung function."

"Technegas as a SPECT ventilation agent has a key advantage as it remains fixed after inhalation, which allows imaging of upright ventilation distribution, analogous of pulmonary function tests."

"V/Q SPECT, using Technegas as the ventilation imaging agent, could diagnose and grade severity of COPD and also estimate preserved lung function in 94 patients. Moreover, V/Q SPECT appears to be a unique tool to reveal the heterogeneity of COPD caused by pulmonary comorbidities such as pulmonary embolism, left heart failure, lung tumor and pneumonia."

"An advantage of using Technegas as the ventilation agent and radiolabelled macro-aggregated albumin microspheres as the perfusion agent is that the deposition pattern is fixed upon administration and thus different patient postures can be studied and the effect of gravity and position determined, even though the scans must be acquired with the subject supine using conventional gamma camera SPECT/CT systems"

"Technetium-99m (99mTc-Technegas) is widely available and relatively inexpensive while Xenon-133 is less than ideal for SPECT imaging owing to its relatively low energy and suboptimal spatial resolution."

"However, the standard technique for V/Q SPECT in the US involves the use of Xenon radiotracer rather than Technegas rendering direct comparison of equivocal rates less useful."