AJP - Heart and Circulatory Physiology, Vol 242, Issue 5 849-H854, Copyright © 1982 by American Physiological Society
Regional myocardial radiotracer kinetics in dogs using miniature radiation detectors
M. L. Jacobs, R. D. Okada, W. M. Daggett, B. N. Fowler, H. W. Strauss, G. Geffin and G. M. Pohost
An implantable device for continuous measurement of regional myocardial
radioisotope activity was designed and validated. The probe consists of a
2-mm3 cadmium telluride crystal surrounded by lead foil housed in a 4.5-mm
outer diameter steel cylinder. Activity in serial dilutions of thallium-201
measured by this miniature gamma detector correlated well with activity
measured in the well counter (r = 0.99). In vivo probe measurements of
regional myocardial thallium-201 activity in a canine model were compared
with activity in punch biopsies, again with excellent correlation (r =
0.90). The crystal was mounted on a modified arterial clamp, which was
inserted into the left ventricle through, the apex and situated on the
endocardial surface of the anterior or posterior wall. It was thus possible
to measure regional isotope activity without excessive background from the
blood pool and opposite heart wall. The probe was found best suited for
monitoring activities of isotopes with energies between 60 and 250 keV.
With a pair of these devices, dynamic studies of the myocardial kinetics of
radioisotopes such as thallium-201 in normal and ischemic myocardium are
now possible.
