Tetsuya Torio MD, Abstract Co-Author: Nothing to Disclose

Waseem Amir Bashir MBChB, Presenter: Nothing to Disclose

Francis William Smith MD, Abstract Co-Author: Nothing to Disclose

Keisuke Takahashi, Abstract Co-Author: Nothing to Disclose

Malcolm Pope PhD, Abstract Co-Author: Nothing to Disclose

In-vivo quantitative analysis of MR images has never been performed to assess changes in intervertebral disc (IVD) water content in different seated postures. We investigated normal subjects lumbar spines in different sitting positions using positional MR imaging and determined the optimal seating posture after comparing IVD water content for each position.

20 healthy individuals with no history of low back pain or surgery were scanned supine and in various sitting positions using a 0.6T positional whole-body MRI. Sagittal T2-weighted scans were performed with a water content calibration phantom taped to the back. This consisted of eight tubes filled with differing concentrations of H2O/D2O solution. Pixel intensity was measured of the phantoms and each of the lumbar IVDs in every position. Calibration curves were subsequently generated and the water content of the IVDs was calculated by interpolation from these curves.

At the L1/2, L2/3, and L3/4 levels the water content of IVDs showed no significant difference in each of the sitting positions. However, at the L4/5 and L5/S1 levels, statistical analysis showed that the water content decreased significantly in order of supine position (L4/5: 41.9%, L5/S1: 39.6%), 135º thigh-trunk sitting position (37.6%, 36.1%), 90º upright sitting position (34.7%, 31.8%), and forward-flexed position (32.7%, 29.2%).

Water content of lumbar IVDs reduced due to weight bearing especially in a flexed sitting position. Positional MRI has shown that a 135º thigh-trunk posture has advantages on the water content of IVDs over a usual upright 90º sitting posture.

This is the first study to show in-vivo changes of water content of lumbar IVDs in different seated postures. A 135º sitting posture shows the best biomechanical sitting position.

Torio, T, Bashir, W, Smith, F, Takahashi, K, Pope, M, Alteration of Water Content in Lumbar Intervertebral Discs Related to Variable Sitting Postures Using Whole-body Positional MR Imaging.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4441036.html