The invention provides methods for predicting, diagnosing or monitoring acute cardiac disorders, cardiac transplant rejection, or distinguishing acute cardiac disorders from pulmonary disorders, by measuring BNP signal peptide levels in a sample taken from a subject shortly after onset of, or presentation with the disorder or transplant rejection. A pump drive mechanism with a drive shaft is located inside the crankcase and the drive shaft is mounted on bearings that are arranged in the walls of the crankcase. Imaging of the voxels within the tilted planar segment for reading is through a two-lens doubly-telecentric afocal lens imaging system to a detector, normally an array of active pixel sensors or charge-coupled devices, located in the conjugate plane.