Osamu Togao MD, PhD, Presenter: Nothing to Disclose

Akio Hiwatashi MD, Abstract Co-Author: Nothing to Disclose

Koji Yamashita MD, PhD, Abstract Co-Author: Nothing to Disclose

Kazufumi Kikuchi MD, Abstract Co-Author: Nothing to Disclose

Tatsuhiro Wada, Abstract Co-Author: Nothing to Disclose

Jochen Keupp PhD, Abstract Co-Author: Employee, Koninklijke Philips NV

Hiroshi Honda MD, Abstract Co-Author: Nothing to Disclose

Glycosaminoglycan CEST (gagCEST) imaging is an emerging molecular MR imaging technique to measure in-vivo glycosaminoglycan content in cartilaginous tissue. The purpose of this study was to evaluate the utility of this method in assessments of lumbar intervertebral disc degeneration (IDD) by comparing with T1-rho, an established quantitative biomarker of IDD, and conventional morphological assessments.

Thirty-six intervertebral discs in nine volunteers (age 32.7 ± 5.9 years; 8 males, 1 female) were examined with both gagCEST imaging and T1-rho measurements. GagCEST imaging was conducted on a 3T MR scanner using a 32-channel torso coil for signal reception and 2-channel parallel transmission via the body coil. A sagittal image covering L2/3, 3/4, 4/5, and L5/S1 levels was acquired using 2D turbo spin-echo sequences with driven equilibrium refocusing. Saturation pulses were irradiated with duration of 1.0 s, and B1 power of 0.8 μT. Other parameters were as follows: TR/TR=5s/6ms, FOV=2302mm2, resolution=1.8×1.8×5mm3, 25 frequency offsets ω=-3..3ppm (step 0.25ppm) and ω = -160 ppm. B0 maps were acquired separately for B0 inhomogeneity correction. CEST effect was defined as: MTRasym = (S[-αppm]-S[+αppm])/S0. GagCEST value was defined as the average CEST effects from 0.5 to 1.5 ppm. For T1-rho measurements, 3D gradient-echo sequence was performed with five spin-lock times (1, 25, 50, 75, 90 ms). A region-of-interest was placed in nucleus pulposus of each intervertebral disc. In addition, T2-weighted images were obtained to assess Pfirrmann grading for morphological assessment of IDD.

The number of intervertebral discs with Pfirrmann grading 1, 2, 3, 4, 5 was 13, 13, 1, 7, 2, respectively. GagCEST values significantly correlated with T1-rho (r = 0.63, P< 0.0001, linear regression) in lumbar intervertebral discs. Both gagCEST values (r = -0.76, P < 0.0001, Spearman rank correlation) and T1-rho (r = -0.65, P < 0.0001, Spearman rank correlation) correlated with Pfirrmann grades.

GagCEST correlated with T1-rho and Pfirrmann grades in lumbar IDD. GagCEST can provide a quantitative measure to assess IDD.

GagCEST imaging correlated with both quantitative T1-rho measurements and qualitative morphological assessments of IDD in the lumbar spine, and thus GagCEST can be a noninvasive and quantitative biomarker of IDD.

Togao, O, Hiwatashi, A, Yamashita, K, Kikuchi, K, Wada, T, Keupp, J, Honda, H, Assessment of Glycosaminoglycan Content in Lumbar Intervertebral Discs with Chemical Exchange Saturation Transfer Imaging: Comparison with T1-rho Measurement.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14012697.html