MRI VOLUMETRY OF THE HIPPOCAMPUS - THE EFFECT OF SLICE THICKNESS ON VOLUME FORMATION

The hippocampus is a mesial temporal lobe structure of complex shape a nd the main locus of temporal lobe epilepsy and also affected early in Alzheimer's disease, Magnetic resonance imaging of the hippocampus ha s been found to be a helpful diagnostic tool for these conditions, Mea surement of hippocampal volumes has been found to be not only the most accurate approach to evaluation of the hippocampal pathology, but the most demanding and time consuming as well, One of the factors contrib uting to this is the slice thickness-the thinner the slice, the more t ime is required, On the other hand, it has been hypothesized, that the use of thick slices would result in volume aberrations due to, for ex ample, the volume averaging effect, We therefore measured the volumes of the hippocampus on coronal slices in 10 healthy, young control subj ects using slice thicknesses of 1, 3 and 5 mm, and evaluated the effec t of the slice thickness on the volume formation, No significant diffe rence between the volumes of the hippocampus using different thickness es was found, Therefore, it appears that use of the thick slices would not necessarily introduce systematic bias to the volumetric measureme nt, Yet, we do not feel compelled to advise the use of ''thick'' slice s either, since the use of ''thin'' slices seems the most authoritativ e and less vulnerable to being affected by a single false estimate, (C ) 1997 Elsevier Science Inc.