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Technegas™ is an ultra-fine dispersion of Technetium-labelled carbon, produced by heating Technetium-99m in a carbon crucible for a few seconds at 2,750 degrees Celsius1. The resultant gas-like Technegas™, thus produced in a TechnegasPLUS generator, is a dispersion of nanosized (average size 30-60nm) pure carbon platelets of hexagonal shape fully encapsulating Technetium metal crystals2. The small size and hydrophobic properties together confirm ideal characteristics for gas-like behaviour and alveoli deposition into the lungs2-3. Technegas™ penetrates to the sub-segmental areas of the lung and is trapped by surfactant in the alveolar walls4.

Once inhaled by the patient suspected of having a pulmonary embolism (PE), the patient is then imaged under a gamma camera in the ventilation part of a ventilation/perfusion single-photon emission computed tomography (V/Q SPECT) scan3. Generated into a mobile generator, Technegas™, used in the ventilation part of the V/Q scan, is cost-effective, simple to perform and accurate5. With the uptake in SPECT imaging, V/Q SPECT results with Technegas™ can be argued to be superior to planar imaging and computed tomography (CT) when comparing sensitivity, accuracy and negative predictive value6-7.

Of significant interest, when compared to CT, is the low radiation dose imparted by V/Q SPECT imaging8. This is important in all patients but particularly in young women with proliferating breast tissue9.

Lung scintigraphy has a superior sensitivity combined with adequate specificity and low rate of non-diagnostic tests. The low radiation dose, the possibility to quantify the degree of embolism and to use the test for follow-up of treatment of embolism and its feasibility in very sick patients, contribute to the priority of lung scintigraphy over Computed Tomographic Pulmonary Angiography ” 10

Diagnostic ability of V/Q SPECT/CT, V/Q SPECT, CTPA and V/Q Planar to detect PE

Table 1: Diagnostic ability of V/Q SPECT/CT7, V/Q SPECT7, CTPA7 and V/Q Planar6 to detect PE
(adapted from Reinartz et al, 2004 and from Hess and al, 2016 )

With the advent of SPECT and SPECT/CT technology, significant improvements in ventilation-perfusion imaging have been made, not only in our ability to resolve subtle heterogeneity in ventilation and perfusion distributions but also in providing relative quantification of ventilation and perfusion11 “

Table 2: Functional and quantitative lung imaging. Images and 3D quantification provided by

As a result of these technical improvements, advanced quantitative V/Q SPECT/CT with Technegas™ could be used as a tool for pre-operative evaluation, monitoring disease progression and following-up treatment response12-13 in a range of conditions whereas functional imaging of alveolar spaces are required, including for:

Pulmonary embolism
Chronic Thromboembolic Pulmonary Hypertension
Chronic Obstructive Pulmonary Disease
Pre-operative quantification of lung function
Radiotherapy treatment planning

To learn more about Technegas™ clinical capabilities, visit our clinical page


Benefits of Technegas™ V/Q SPECT

      Diagnostic accuracy: 

Sensitivity, specificity and accuracy at least equivalent to CTPAgiving the clinician interpretative confidence in diagnosing PE event at subsegmental levels6,14.

     3D images:

The gas-like behaviour of Technegas™ coupled with the ideal energy of Tc-99m gives excellent penetration to peripheral areas3,15. Images may be acquired in multiple projections facilitating image interpretation16 .

      Low radiation burden to the patient:

V/Q SPECT with Technegas™ has 27 to 36 times less radiation dose to the patient breast as compared with CTPA8.


     Quick and simple:

Rapid and easy administration of Technegas™ 15 (3-4 breaths only) allowing accurate and quick decisions even in case of lung obstructive disease16.

     Minimal exclusion criteria:

Technegas™ may be administered to almost all patients including patients with renal impairment17, iodinated contrast allergy17 and chronic lung obstruction disease18. Technegas™ should be also favoured in young women of child-bearing age8,16 and in pregnant women8-9.


Because Technegas™ is easy to breath, it aids patients’ comfort and compliance.

Useful documents

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  1. Fawdry RM, et al. Initial experience with Technegas – a new ventilation agent. Australas Radiol 1988; 32(2): 232-238
  2. Senden TJ, et al. The physical and chemical nature of Technegas. J Nucl Med 1997; 38: 1327-1333
  3. Roach PJ, Schembri GP and Bailey DL. V/Q scanning using SPECT and SPECT/CT. J Nucl Med 2013; 54: 1588-1596
  4. Mortensen J and Gutte H. SPECT/CT and pulmonary embolism. Eur J Nucl Med Mol Imaging 2014; 41(Suppl1): 81-90
  5. Roach PJ, Bailey DL, Harris BE. Enhancing lung scintigraphy with single-photon emission computed tomography. Semin Nucl Med 2008; 38: 441–449
  6. Reinartz P, et al. Tomographic imaging in the diagnosis of pulmonary embolism: A comparison between V/Q lung scintigraphy in SPECT technique and multislice spiral CT. J Nucl Med 2004; 45: 1501-1508
  7. Hess S, et al. State-of-the-Art Imaging in Pulmonary Embolism: Ventilation/Perfusion Single-Photon Emission Computed Tomography versus Computed Tomography Angiography — Controversies, Results, and Recommendations from a Systematic Review. Semin Thromb Hemost 2016; 42: 833–845
  8. Isidoro J, et al. Radiation dose comparison between V/P-SPECT and CT-angiography in the diagnosis of pulmonary embolism. Phys Med 2017; 41: 93-96
  9. Bajc et al. V/P SPECT as a diagnostic tool for pregnant women with suspected pulmonary embolism. Eur J Nucl Mol Imaging 2015; 42: 1325-1330
  10. Bajc et al. Comparison of ventilation/perfusion scintigraphy and helical CT for diagnosis of pulmonary embolism; strategy using clinical data and ancillary findings. Clin Physiol Funct Imaging 2002; 22(6): 392-397
  11. Elojeimy S, et al. Overview of the novel and improved pulmonary ventilation-perfusion imaging applications in the era of SPECT/CT. AJR Am J Roentgenol 2016; 207(6): 1307-1315
  12. Inmai T, et al. Clinical evaluation of 99mTc-Technegas SPECT in thoracoscopic lung volume reduction surgery in patients with pulmonary emphysema. Ann Nucl Med 2000; 14(4): 263-269
  13. Hsu K, et al. Endoscopic lung volume reduction in COPD: improvements in gas transfer capacity are associated with improvements in ventilation and perfusion matching. J Bronchology Interv Pulmonol 2018; 25(1): 48-53
  14. Grüning T, et al. Three-year experience with VQ SPECT for diagnosing pulmonary embolism: diagnostic performance. Clin Imaging 2014; 38(6): 831-835
  15. Bajc M and Jonson B. Ventilation/perfusion SPECT for diagnosis of pulmonary embolism and other diseases. Int J Mol Imaging 2011; 682949
  16. Hess S and Madsen PH. Radionuclide diagnosis of pulmonary embolism. Adv Exp Med Biol 2017; 906: 49-65
  17. Miles S, et al. A comparison of single-photon emission CT lung scintigraphy and CT pulmonary angiography for the diagnosis of pulmonary embolism. Chest 2009; 136: 1546-1553
  18. Nasr A, Lindqvist A and Bajc M. Ventilation defect typical for COPD is frequent among patients suspected for pulmonary embolism but does not prevent the diagnosis of PE by V/P SPECT. EC Pulmonology and Respiratory Medicine 2017; 4(3): 85-91
  19. Sánchez-Crespo A, et al. A technique for lung ventilation-perfusion SPECT in neonates and infants. Nucl Med Commun 2008; 29(2): 173-177



Pending market authorisation

Ultralute is a revolutionary innovation that allows Nuclear Medicine departments to increase the productivity of their Tc-99m generator. It does this by allowing you to elute any amount of activity in approximately 2ml. By increasing the concentration of Tc-99m from an elution, the decay profile and the growth of Tc-99m from a Mo-99m/Tc 99m generator can be better utilised.