Medical Health Encyclopedia

Magnetic Resonance Imaging. Magnetic resonance imaging (MRI) is an advanced imaging procedure that does not use radiation, as x-rays do. It is expensive, however, and not generally used for an initial diagnosis. MRI can, nevertheless, identify spinal cord and brain stem abnormalities, which some studies indicate may be more prevalent than previously believed in children with idiopathic scoliosis. It also may be particularly useful before surgery for detecting defects that could lead to potential complications.

Click the icon to see an image of a MRI scan.

Determining the Extent of the Curve

There are various methods for determining and classifying the extent of the curve.

Cobb Method. The degree of the curve is nearly always calculated using a technique known as the Cobb method.

• On an x-ray of the spine, the examiner draws two lines: One line extends out and up from the edge of the top vertebrae of the curve. The second line extends out and down from the bottom vertebrae.
• A perpendicular line is then drawn between the two lines.
• The intersecting angle is measured to determine the degree of curvature.

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The Cobb method is limited because it cannot fully determine the flexibility or the three-dimensional aspect of the spine. It is not as effective, then, in defining spinal rotation or kyphosis. It also tends to over-estimate the curve. Other diagnostic tools are needed then to make a more accurate diagnosis.

Classifying the Curve.Classification of the curve allows the physician to identify patterns that can help determine treatments, particularly specific surgical techniques. The following are examples:

• King Classification. The King classification classifies scoliotic curves as one of five patterns, which can help determine surgical treatments. It has limitations, however, and is not very useful for advanced surgical techniques.
• Lenke Classification. Lenke classification takes more features of the curve into consideration and is proving to be more reliable. This includes six curve patterns plus addition factors that modify each of these curves.