Synchrotron-Based High Angle Resolution and High Lateral Resolution X-ray Diffraction: Revealing Lead White Pigment Qualities in Old Masters Paintings.

Microsamples collected on 27 major paintings by Old European Masters dating from the 14th to the late 19th centuries were analyzed using synchrotron-based X-ray diffraction. Two complementary analytical configurations were used at beamlines ID22 (high angle resolution) and ID21 (high lateral resolution), in order to highlight markers of the different grades of the lead white pigments (mixture of cerussite PbCO3 and hydrocerussite Pb3(CO3)2(OH)2). Rietveld analysis and crystalline phases mapping at the microscale revealed the composition and microstructure of the pigments, shedding light on the preparation recipes and pigment choices of the artists through History.

[Upper cervical intradural lipoma. Apropos of a case]. / Lipome intradural cervical haut. A propos d'une observation.

Intradural lipoma is a rare and slow growing tumor which represents 1% of all intra-spinal tumors. This tumor is often associated with dysraphism. It can be isolated without any associated vertebral or cutaneous malformations. Its clinical evolution is extremely slow and progressive. The fatty composition of this type of tumor allows easy detection by CT as well as by MRI. MRI permits: Reliable and direct assessment (in 3 different plans) of the extension of the lesion. An excellent post operative control.

Anatomy of the acromial arch: correlation of anatomy and magnetic resonance imaging.

Based on a retrospective study of 179 MRI records covering four populations (patients presenting with impingement without known injury (n = 90), post-traumatic shoulder pain (n = 28), instability or dislocation (n = 36) and controls (n = 25)), morphologic criteria are suggested to define presumedly normal arches and arches compatible with subacromial impingement. The subacromial arch is presumed normal or without impingement if the sagittal and frontal views show it to be parallel to the humeral head, and/or if there is a fatty layer interposed between the arch and the supraspinatus m. The arch is presumed "aggressive" or actually capable of giving rise to impingement if, in either the sagittal or frontal view, there is a zone of narrowing of the subacromial passage with an impression of the arch on the supraspinatus tendon or tendinous thinning at this level or just lateral to this narrowed zone. Based on these criteria, study of the 179 MRI records demonstrated a significant difference of distribution of the arches in the four populations. "Aggressive" arches were found in 45.5% of patients with impingement, 25% of patients with posttraumatic pain, 8.9% of patients with an acute or recurrent dislocation and 12% of controls. Conversely, a presumedly normal arch was found in 56% of the controls, 55% of patients with dislocation, 25% of posttraumatic painful shoulders and only 5.5% of patients with clinical impingement. Subacromial impingement may be due to the type 3 acromial dysplasia described by Bigliani or to a thickening of the coracoacromial ligament at its acromial attachment. This study was supplemented by 15 anatomic dissections which confirmed the regularity of attachment of the coracoacromial ligament at the inferior aspect of the acromion along its lateral border.