Simultaneous measurement of left ventricular function and perfusion.

A new radiopharmaceutical, methylisobutyl isonitrile (MIBI), has been developed as a technetium-99m-labelled alternative to thallium 201 for myocardial imaging. By virtue of the high specific activity of 99mTc, some 600 MBq may be administered as a 0.3 ml bolus, permitting the acquisition of a first-pass nuclear angiogram at rest and at peak exercise. The agent was assessed in ten sequential patients referred for routine cardiac catheterisation, who also underwent an exercise electrocardiographic (ECG) test. Good quality nuclear angiograms, planar perfusion and tomographic perfusion images were obtained; the results correlated well with the catheterisation data. Of 30 myocardial segments for which wall motion was judged normal/abnormal from the nuclear angiogram, results concordant with contrast studies were obtained in 27 (90%). In the case of the 50 segments analysed from the perfusion images, concordant results were obtained in 43 (86%) from the planar studies and in 42 (84%) from the tomographic studies. All normal segments were classified correctly.