The VEX-test for myocardial scintigraphy with thallium-201 and sestamibi: effect on abdominal background activity.
High abdominal background activity of 99mTc-sestamibi may interfere with the diagnosis in studies in which a coronary vasodilator is used; supplemental dynamic exercise might reduce this problem.


METHODS
Clinical and angiographic determinants of subdiaphragmatic-to-myocardial activity ratios were measured on immediate poststress left anterior oblique images and on corresponding tomographic studies 1 hr after injection in 600 sestamibi studies. Similar measurements were made in 550 historic controls with planar 201Tl imaging. Patients performed symptom-limited ergometry when there were no limiting factors, dipyridamole-handgrip in which ergometry was not possible and VEX (vasodilator followed by symptom-limited ergometry) in which exercise capacity was reduced.


RESULTS
Abdominal activity was higher with sestamibi than with 201Tl, in women versus men, and with dipyridamole-based tests compared to exercise alone. Compared to the dipyridamole-handgrip, 3 min of ergometry as part of VEX decreased abdominal background (p < or = 0.02) by 18% on immediate 201Tl images, by 13% on immediate sestamibi images and by 12% on 1-hr delayed sestamibi tomoacquisitions.


CONCLUSIONS
Poststress abdominal background activity is influenced by similar factors with both agents. Supplemental exercise following dipyridamole reduces potentially interfering abdominal activity but perhaps not as efficiently with sestamibi as with 201Tl.
Hurwitz
G A
GA
Department of Diagnostic Radiology, University of Western Ontario, London, Canada.
Saddy
S
S
O'Donoghue
J P
JP
Ali
S A
SA
Powe
J E
JE
Husni
M
M
Gravelle
D R
DR
D000005:Abdomen / Q000000981:diagnostic imaging*; D017023:Coronary Angiography; D003327:Coronary Disease / Q000000981:diagnostic imaging; D004176:Dipyridamole; D005080:Exercise Test; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D011877:Radionuclide Imaging; D017256:Technetium Tc 99m Sestamibi; D013794:Thallium Radioisotopes
D013794:Thallium Radioisotopes; D004176:Dipyridamole; D017256:Technetium Tc 99m Sestamibi