No abstract

Background: There is presently insufficient data on small groups of patients, without focus on time since herniation occurred and without establishing a valid method of measurement for signal intensity (SI) of a lumbar disc herniation (LDH) in a standard magnetic resonance imaging (MRI). SI could be reported in relation to SI of nucleus pulposus of herniated intervertebral disc, nucleus pulposus of a healthy ''control'' intervertebral disc, cerebral spinal fluid, or anterior anulus fibrosus. It is not known which signal intensity ratio (SIR) shows the highest correlation with time since onset of pain and how SIR of different Combined Task Forces (CTF)-types of herniation develop over time. Methods: Out of 1053 patients, we enrolled 151 patients to a retrospective single-center analysis of standard MRIs of consecutive patients treated for LDH from February 2008 to December 2017 with confirmed (surgery, injection, or electrophysiologic testing) radicular pain by LDH and known exact date of onset of pain. We excluded patients , 18 or. 70 years, with chronical pain syndrome, spinal deformity, and history of prior spinal surgery on the affected spinal level. Because data did not show normal distribution, we assessed correlation by Spearman rank correlation coefficient. Correlation (R) and coefficient of correlation (CC) are reported. Results: SI of LDH referenced by SI of nucleus pulposus of the affected intervertebral disc and CTF type ''extrusion'' showed the highest correlations with time since onset of pain (R: À0.893; CC: 79.7), followed by CTF-type ''sequestration'' (R: À0.356; CC: 12.7). Conclusions: SIR of extrusion referenced by nucleus pulposus of the affected intervertebral disc does show a high correlation with days since onset of herniation and may be applied to monitor changes of SI of LDH after herniation in standard MRIs of the lumbar spine.

Lumbar intervertebral disc (IVD) degeneration is characterized by structural and compositional changes. This study aimed to assess the glycosaminoglycan (GAG) content of IVDs of patients with adolescent idiopathic scoliosis (AIS) and healthy controls using GAG chemical exchange saturation transfer (gagCEST) imaging. Ten AIS patients (mean age 18.3 ± 8.2 years) and 16 healthy controls (mean age 25.5 ± 1.7 years) were included. Clinical standard morphologic MR images (T1w-, T2w-, and STIR-sequences), to rule out further spinal disorders and assess IVD degeneration using the Pfirrmann score, and compositional gagCEST sequences were acquired on a 3T MRI. In AIS patients, the most distal scoliotic curve was determined on whole-spine conventional radiographs and morphological MRI and IVDs were divided as to whether they were affected by scoliotic deformity, i.e., proximal (affected, aIVDs) or distal (unaffected, uaIVDs) to the stable vertebra of the most distal scoliotic curve. Linear mixed models were used to compare mean gagCEST-values. Over all segments, AIS-patients’ IVDs exhibited significantly lower gagCEST-values than the controls: 2.76 [2.32, 3.20]% (AIS), 3.51 [3.16, 3.86]% (Control); p = 0.005. Meanwhile, no significant differences were found for gagCEST values comparing aIVDs with uaIVDs. In conclusion, as a powerful diagnostic adjunct, gagCEST imaging may be prospectively applied to detect early compositional degenerative changes in patients suffering from AIS.

Purpose Reports on heterogenous groups of patients have indicated that pedicle screw insertion guided by navigation (PIN) leads to, for the patient, higher doses of radiation compared with pedicle screw insertion guided by fluoroscopy (PIF). This would be a major concern, especially in paediatric deformity correction. Methods After a power analysis (aiming at > 0.8) 293 pedicle screws which were inserted in patients with adolescent idiopathic scoliosis were analyzed by comparing effective dose and fluoroscopy time per screw for three different techniques. Groups 2 and 3 were matched to Group 1 by Lenke type of scoliosis. Group 1 were prospectively enrolled consecutive patients that have been operated on by PIN with image acquisition by preoperative CT scan (CTS). Group 2 were consecutive retrospectively matched patients who have been operated on by PIN with image acquisition by an intraoperative 3D scan (3DS). Group 3 were consecutive retrospectively matched patients who have been operated on by PIF. Results Mean dose of radiation per screw was 1.0 mSv (sd 0.8) per screw in CTS patients, 0.025 mSv (sd 0.001) per screw in 3DS patients and 0.781 mSv (sd 0.12) per screw in PIF patients. The difference was significant (p < 0.0001). Conclusion When we compared different techniques of navigation, navigation by image acquisition with CTS showed a significantly higher (by 97.5%) dose of radiation per screw for the patient than navigation by image acquisition by a 3DS. Navigation by 3DS showed significantly lower effective dose per screw for the adolescent patients than the fluoroscopic technique. Level of Evidence: II