Radiological findings in ancient Egyptian canopic jars: comparing three standard clinical imaging modalities (x-rays, CT and MRI)

Abstract

Background: The aim of our study was to evaluate the potential and the limitations of standard clinical imaging modalities for the examination of ancient Egyptian canopic jars and the mummified visceral organs (putatively) contained within them.

Methods: A series of four ancient Egyptian canopic jars was imaged comparing the three standard clinical imaging modalities: x-rays, computed tomography (CT) and magnetic resonance imaging (MRI). Additionally, imaging-data-based volumetric calculations were performed for quantitative assessment of the jar contents.

Results: The image contrast of the x-ray images was limited by the thickness and high density of the calcite mineral constituting the examined jars. CT scans showed few artefacts and revealed hyperdense structures of organ-specific morphology, surrounded by a hypodense homogeneous material. The image quality of MRI scans was limited by the low amount of water present in the desiccated jar contents. Nevertheless, areas of pronounced signal intensity coincided well with hyperdense structures previously identified on CT scans. CT-based volumetric calculations revealed holding capacities of the jars of 626-1319 cm³ and content volumes of 206-1035 cm³.

Conclusions: CT is the modality of choice for non-invasive examination of ancient Egyptian canopic jars. However, despite its limitations, x-ray imaging will often remain the only practicable method for on-site investigations. Overall, the presented radiological findings are more compatible with contained small organ fragments rather than entire mummified organs, as originally expected, with consequent implications for envisioned future sampling for chemical and genetic analysis.

Keywords: Ancient Egyptian canopic jars; Computed tomography; Magnetic resonance imaging; Paleoradiology; Radiography.

Fig. 1

Ancient Egyptian canopic jars on display in the Egyptian collection of the Archaeological Museum in Zagreb, Croatia (with kind permission of the Archaeological Museum in Zagreb, Croatia)

Fig. 2

CT-based density measurements. Placement of regions of interest A and A’ (calcite mineral), B and B′ (surrounding material) and C and C′ (structures of higher radiodensity) for two canopic jars (inventory numbers 610-2 and 607) on sagittal multiplanar reconstructions (slab thickness 1.5 mm)

Fig. 3

Three-dimensional surface reconstructions and volume calculations of one canopic jar (inventory number 607) obtained with Rhinoceros 3D. From left to right: volume including jar contents (−350 HU threshold), volume of calcite jar only (900 HU threshold), calculated volume of actual contents and calculated maximal holding capacity

Fig. 4

CT scans, sagittal cross sections through the centre of the jars (top) and correlative 3D volume renderings (bottom) of all four canopic jars (a, inventory number 607; b, inventory number 617; c, inventory number 622-1; d, inventory number 610-2). In panel a, arrows indicate a distinct hyperdense structure of organ-fragment-like morphology, probably intestine

Fig. 5

CT reconstructions (top) and correlative maximum intensity projections of MRI scans (bottom) of the three canopic jars with solid contents (a, inventory number 607; b, inventory number 617; c, inventory number 622-1). Black arrows (on CT) and white arrows (on MRI) indicate structures of organ-fragment-like morphology, probably intestine

Fig. 6

Direct comparison of the three imaging modalities: x-rays (a, d), CT (b, e) and MRI (c, f) of the canopic jars with the smallest and the largest diameter (a–c, inventory number 617; d–f, inventory number 622-1)