 cesium-131 uptak distribut human heart analysi cardiac scan 104 patient properli cesium-131 satisfactori agent studi cardiac morpholog photoscan adjunct diagnost procedur patient method evalu varianc clinic symptom cardiac diseas studi report infarct subclin type size locat occur earlier thought damag leav detect autopsi techniqu scan measur actual concentr cesium-131 heart autopsi cold cool area examin histolog section 