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Use of CT in Detection of Internal Damage and Repair and Determination of Authenticity in High-Quality Bowed Stringed Instruments¹

¹ From Consulting Radiologists, Abbott Northwestern Hospital, 800 E 28th St, Minneapolis, MN 55407 (S.A.S.), and John R. Waddle Violins, St Paul, Minn (J.R.W.). Presented as a scientific exhibit at the 1997 RSNA scientific assembly. Received March 26, 1998; revision requested April 29 and received July 6; accepted July 9. Address reprint requests to S.A.S.

View larger version (36K): [in a new window]   Figure 1. Figures 1, 2. (1) Schematic shows front and side views of a typical violin. The spruce front plate on the bass side of the instrument has been removed, exposing the blocks, the linings, and the maple ribs. The spruce sound post would be carefully positioned between the front and back plates, near the foot on the treble side of the bridge. The spruce bass bar (dashed line) is attached on the inner surface of the front plate directly beneath the foot on the bass side of the bridge. (2) Schematic demonstrates a transaxial view of a violin through the middle bout at the level of the bridge. Note the f-holes located between the foot of the bridge and the edge of the front plate. The linings attach the front and back plates to the ribs. (Figs 1 and 2 reprinted, with permission, from reference 3.)

View larger version (18K): [in a new window]   Figure 2. Figures 1, 2. (1) Schematic shows front and side views of a typical violin. The spruce front plate on the bass side of the instrument has been removed, exposing the blocks, the linings, and the maple ribs. The spruce sound post would be carefully positioned between the front and back plates, near the foot on the treble side of the bridge. The spruce bass bar (dashed line) is attached on the inner surface of the front plate directly beneath the foot on the bass side of the bridge. (2) Schematic demonstrates a transaxial view of a violin through the middle bout at the level of the bridge. Note the f-holes located between the foot of the bridge and the edge of the front plate. The linings attach the front and back plates to the ribs. (Figs 1 and 2 reprinted, with permission, from reference 3.)

View larger version (42K): [in a new window]   Figure 3. Figures 3, 4. (3) High-resolution transaxial CT scan of a valuable violin reveals a network of wormholes in the peg box. The high-attenuation structure is an ebony peg. (4) High-resolution transaxial CT scan of a Venetian cello demonstrates a network of wormholes (arrow) in the scroll. A small amount of glue is seen at the edge of the scroll (arrowhead).

View larger version (66K): [in a new window]   Figure 4. Figures 3, 4. (3) High-resolution transaxial CT scan of a valuable violin reveals a network of wormholes in the peg box. The high-attenuation structure is an ebony peg. (4) High-resolution transaxial CT scan of a Venetian cello demonstrates a network of wormholes (arrow) in the scroll. A small amount of glue is seen at the edge of the scroll (arrowhead).

View larger version (74K): [in a new window]   Figure 5. Figures 5, 6. (5) High-resolution transaxial CT scan of a Stradivarius violin shows an air gap (white arrow) between the rib and an internal corner block. Note the two air-glue interfaces between the inner surface of the rib and the inner corner block (black arrows). Arrowheads indicate the back plate. (6) High-resolution transaxial CT scan of the front plate of a very old and valuable Stradivarius violin shows mild, asymmetric plastic deformity of the front plate and tilting deformity of the ebony fingerboard.

View larger version (30K): [in a new window]   Figure 6. Figures 5, 6. (5) High-resolution transaxial CT scan of a Stradivarius violin shows an air gap (white arrow) between the rib and an internal corner block. Note the two air-glue interfaces between the inner surface of the rib and the inner corner block (black arrows). Arrowheads indicate the back plate. (6) High-resolution transaxial CT scan of the front plate of a very old and valuable Stradivarius violin shows mild, asymmetric plastic deformity of the front plate and tilting deformity of the ebony fingerboard.

View larger version (89K): [in a new window]   Figure 7. Figures 7–9. (7) High-resolution transaxial CT scan of the scroll of an old and valuable Italian violin shows a linear region of high attenuation (arrow), consistent with glue repair. (8) High-resolution transaxial CT scan of the peg box of a valuable violin shows a linear area of high attenuation that represents glue repair (arrow). (9) High-resolution transaxial CT scan of the scroll of an old Italian violin demonstrates wormholes (arrowhead) and high-attenuation filler material (arrow) occupying a large volume of the scroll. Multiple wormholes several millimeters in diameter were visible on the surface of the scroll. An expert luthier had painted a wood grain pattern on the surface to conceal the filler material.

View larger version (67K): [in a new window]   Figure 8. Figures 7–9. (7) High-resolution transaxial CT scan of the scroll of an old and valuable Italian violin shows a linear region of high attenuation (arrow), consistent with glue repair. (8) High-resolution transaxial CT scan of the peg box of a valuable violin shows a linear area of high attenuation that represents glue repair (arrow). (9) High-resolution transaxial CT scan of the scroll of an old Italian violin demonstrates wormholes (arrowhead) and high-attenuation filler material (arrow) occupying a large volume of the scroll. Multiple wormholes several millimeters in diameter were visible on the surface of the scroll. An expert luthier had painted a wood grain pattern on the surface to conceal the filler material.

View larger version (89K): [in a new window]   Figure 9. Figures 7–9. (7) High-resolution transaxial CT scan of the scroll of an old and valuable Italian violin shows a linear region of high attenuation (arrow), consistent with glue repair. (8) High-resolution transaxial CT scan of the peg box of a valuable violin shows a linear area of high attenuation that represents glue repair (arrow). (9) High-resolution transaxial CT scan of the scroll of an old Italian violin demonstrates wormholes (arrowhead) and high-attenuation filler material (arrow) occupying a large volume of the scroll. Multiple wormholes several millimeters in diameter were visible on the surface of the scroll. An expert luthier had painted a wood grain pattern on the surface to conceal the filler material.

View larger version (20K): [in a new window]   Figure 10a. Figures 10, 11. (10a) High-resolution transaxial CT scan of a Stradivarius violin shows a wooden cleat (arrow) glued to the inside surface of the front plate. (10b) High-resolution coronal CT scan of the front plate shows multiple wooden cleats (arrowheads) and the large, round wooden patch (open straight arrow), which involves almost the entire middle bout of the violin. Note the relationship between the f-holes, the bass bar (solid curved arrow), the sound post (solid straight arrow), and the foot of the bridge distal to the sound post (open curved arrow). (11) High-resolution transaxial CT scan of the front plate of a high-quality Venetian cello shows the typical appearance of an internal wooden patch (bracket) and its interface with the original front plate (arrows). Note the discontinuity between the grain pattern of the original front plate and that of the embedded wooden patch. This patch occupied nearly 50% of the thickness of the original front plate.

View larger version (86K): [in a new window]   Figure 10b. Figures 10, 11. (10a) High-resolution transaxial CT scan of a Stradivarius violin shows a wooden cleat (arrow) glued to the inside surface of the front plate. (10b) High-resolution coronal CT scan of the front plate shows multiple wooden cleats (arrowheads) and the large, round wooden patch (open straight arrow), which involves almost the entire middle bout of the violin. Note the relationship between the f-holes, the bass bar (solid curved arrow), the sound post (solid straight arrow), and the foot of the bridge distal to the sound post (open curved arrow). (11) High-resolution transaxial CT scan of the front plate of a high-quality Venetian cello shows the typical appearance of an internal wooden patch (bracket) and its interface with the original front plate (arrows). Note the discontinuity between the grain pattern of the original front plate and that of the embedded wooden patch. This patch occupied nearly 50% of the thickness of the original front plate.

View larger version (36K): [in a new window]   Figure 11. Figures 10, 11. (10a) High-resolution transaxial CT scan of a Stradivarius violin shows a wooden cleat (arrow) glued to the inside surface of the front plate. (10b) High-resolution coronal CT scan of the front plate shows multiple wooden cleats (arrowheads) and the large, round wooden patch (open straight arrow), which involves almost the entire middle bout of the violin. Note the relationship between the f-holes, the bass bar (solid curved arrow), the sound post (solid straight arrow), and the foot of the bridge distal to the sound post (open curved arrow). (11) High-resolution transaxial CT scan of the front plate of a high-quality Venetian cello shows the typical appearance of an internal wooden patch (bracket) and its interface with the original front plate (arrows). Note the discontinuity between the grain pattern of the original front plate and that of the embedded wooden patch. This patch occupied nearly 50% of the thickness of the original front plate.

View larger version (67K): [in a new window]   Figure 12.  High-resolution transaxial CT scan of a violin demonstrates an internal wooden patch (black arrowhead) positioned between an internal block (white arrow) and the front plate (black arrow). Note the discontinuity between the grain pattern of the newer wooden patch and that of the original front plate. The ebony fingerboard (white arrowhead) has high attenuation.

View larger version (79K): [in a new window]   Figure 13a.  High-resolution transaxial CT scans of the scrolls of a valuable Stradivarius violin (a) and Venetian cello (b) demonstrate internal wood grain patterns unique to these instruments. Such a pattern serves as a "fingerprint" that cannot be altered and enables an instrument to be identified with absolute certainty.

View larger version (69K): [in a new window]   Figure 13b.  High-resolution transaxial CT scans of the scrolls of a valuable Stradivarius violin (a) and Venetian cello (b) demonstrate internal wood grain patterns unique to these instruments. Such a pattern serves as a "fingerprint" that cannot be altered and enables an instrument to be identified with absolute certainty.