The use of Xenon-133 ventilation scan performed immediately after Tc-99m MAA perfusion scan

M. Bocher, N. Shibley, R. Chisin

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


The diagnosis of pulmonary embolism by radionuclide studies is made more probable when a perfusion defect seen on a perfusion scan is unmatched on a ventilation scan. Xe-133 has the advantage of showing three phases of ventilation: wash-in, equilibrium, and wash-out. Performing Xe-133 ventilation and Tc-99m MAA perfusion scans in the same session, however, imposes a major constraint: the ventilation scan should be performed before the perfusion scan. Thus, many laboratories start ventilation-perfusion scans with a ventilation study obtaining a posterior view of the lungs. Therefore, if a perfusion defect is mainly anterior, it is impossible to determine whether the patient has a matched or a mismatched ventilation-perfusion abnormality. The use of a simple method for relating ventilation findings to perfusions abnormalities, as first observed on the perfusion scan, is suggested. This procedure is described below. After performing a usual perfusion study and after determining which lung view best demonstrates the eventual defect, a 60-second frame acquisition of the Tc-99m MAA radioactivity present in the lungs is done using the Xe-133 window (80 Kev ± 15) with the patient in the same position. The image will show Tc-99m scattering into the Xenon window. Another acquisition is then done for 6 seconds while the patient inhales Xe-133. Subtracting the Tc-99m scattering image from the Xe-133 image results in pure ventilatory information. Figure 1 shows how this technique demonstrated the existence of a mismatched ventilation-perfusion defect in the right middle lobe.

Original languageEnglish
Pages (from-to)157-158
Number of pages2
JournalClinical Nuclear Medicine
Issue number2
StatePublished - Feb 1993
Externally publishedYes


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