Pulmonary thromboembolism: a retrospective study on the examination of 991 patients by ventilation/perfusion SPECT using Technegas.

Abstract

PURPOSE:

Conventional planar ventilation/perfusion (V/P)-imaging in those patients suspected of suffering from pulmonary thromboembolism (PTE) is of limited diagnostic value. It is the purpose of this retrospective study to determine whether the use of V/P-SPECT using Technegas might reduce the rate of those diagnostic uncertainties and might lead to better results.

METHODS:

991 patients (660 female, 331 male, age 18-90, mean 60), referred to our laboratory with suspected PTE, were examined as follows: patients inhaled 37 MBq of Technegas in the supine position and a SPECT-acquisition was started. Following SPECT-completion, 185 MBq 99mTc-MAA was injected intravenously. SPECT was then repeated. Coronal and transverse ventilation and perfusion SPECT-slices were reconstructed and compared section by section. 85 patients underwent control scans by the same technique at a mean interval of 22 months after the original scans.

RESULTS:

As the SPECT images in almost all cases made a clear match/mismatch decision possible, we categorized all patients as embolic (PTE+) if there was at least one mismatching defect, and as non embolic (PTE-) if there were none. Our results were: PTE+: 178 patients (18%), PTE-: 808 patients (81%), uncertain: 5 patients (0.5%), if 34 triple-match defects are included: 39 patients (3.9%). 46 patients, categorized as PTE+ underwent a control V/P scan after anticoagulant therapy. In 44 of these patients, PTE was confirmed by the controls. In a control group of 39 PTE- patients, control scans were unchanged in 38 cases. From these observations we can calculate a sensitivity of 96% and a specificity of 97%.

CONCLUSION:

We conclude that V/P imaging can be improved significantly by V/P SPECT using Technegas.

• Authors: M Lemb, H Pohlabeln
• Journal: Nuklearmedizin. Nuclear medicine (Nuklearmedizin) Vol. 40 Issue 6 Pg. 179-86 (Dec 2001) ISSN: 0029-5566 [Print] Germany
• PMID: 11797505 (Publication Type: Journal Article)

Chemical References

• Radiopharmaceuticals
• Technegas
• Sodium Pertechnetate Tc 99m

Topics

• Adult
• Aged
• Aged, 80 and over
• Female
• Humans
• Lung (diagnostic imaging)
• Male
• Middle Aged
• Patient Selection
• Pulmonary Embolism (classification, diagnostic imaging, physiopathology)
• Radiopharmaceuticals
• Retrospective Studies
• Sodium Pertechnetate Tc 99m
• Tomography, Emission-Computed, Single-Photon
• Ventilation-Perfusion Ratio (physiology)