TISSUE CHARACTERIZATION OF SYMPTOMATIC AND ASYMPTOMATIC DISC HERNIATIONS BY QUANTITATIVE MAGNETIC-RESONANCE-IMAGING

The purpose of this investigation was to determine differences in tiss ue composition of symptomatic and asymptomatic disc herniations as ref lected in T-1 and T-2 relaxation times (quantitative magnetic resonanc e imaging). Thirty patients with sciatica severe enough to require a d iscectomy and 46 asymptomatic volunteers (controls) were included in t his study. Both groups had a clinical examination as well as a magneti c resonance investigation of the lumbar spine. The longitudinal and tr ansverse magnetic relaxation times (T-1 and T-2, respectively) were ca lculated from a set of 20 images obtained with five single-slice/multi -echo sequences at different repetition time values on a commercial wh ole-body system (1.5 T). Twenty-two symptomatic and asymptomatic disc herniations could be matched according to age, gender, disc level, and the extent of herniation (protrusion or extrusion) and were compared with regard to T-1 and T-2 relaxation times. Symptomatic disc herniati ons exhibited significantly (p(T1) < 0.04 and p(T2) < 0.003) shorter T -1 (Delta T-1: -182.1 milliseconds, -15%) and T-2 (Delta T-2: -11.0 mi lliseconds, -21%) relaxation times than matched asymptomatic herniatio ns. Symptomatic disc herniations also exhibited more advanced disc deg eneration as graded by Pearce's criteria (p < 0.03). These results sug gest that symptomatic and morphologically matched asymptomatic disc he rniations differ with regard to disc matrix composition.