A Peruvian mummy known as Sabia had been recovered from the ancient ceremonial center at Pachacamac (Figure 3.57). The mummy was scheduled for whole-body evaluation with CT. Since the resources were available MRI was performed. Our initial thoughts were
that given the anhydrous nature of the mummy, MRI would yield little or no information. Our hope was that if the mummy was preserved with resins or oils, there may be minute quantities of trapped moisture that could possibly yield an MR signal. Though initially unsuccessful due to the failure of the automated signal detection and processing built into the system, further attempts with manual tuning were more successful. It should be noted that all commercial MRI scanners have automatic prescan "tuning" software packages. These programs are designed to find the biggest signal peaks and, based on resonant frequency, identify fat and water. The signal was then optimized, and the scan was allowed to proceed.
MRI of the brain was the first exam performed on Sabia. Axial (Figure 3.58A) and sagittal (Figure 3.58B) slices were obtained through the brain from the vertex to the skull base. For correlation, approximate slice positions were compared with corresponding CT slices and reformatted CT images (Figures 3.59A and 3.59B). The same procedure was followed for the chest, abdomen, and pelvic regions.
It should be noted that the increased sensitivity of MRI, one of its greatest benefits, may also be responsible for its failure in some cases. The sensitivity of MRI is measured on the order of parts per million (ppm). This means that MRI can detect anatomical and pathological changes in tissues before they present clinically in many cases. In its application to the field of mummy research, it means that contaminants in the imaged sample can have a devastating negative impact on the final image. The big concern here was the presence of anything metallic within the remains. Metallic contaminants can be from many sources including soil, rock, pieces of broken tools, religious and funerary artifacts, and miscellaneous offerings as seen in the mummy James Penn (Figure 3.60). The magnitude and
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