Edematous Schmorl’s nodes on thoracolumbar MR imaging: characteristic patterns and changes over time

To describe the patterns and note the evolution of edematous Schmorl’s nodes.

In 47 patients (M:F=26:21, 24–86 years, average 60), 84 Schmorls nodes with T2 hyperintensity with serial MR exams were evaluated. Interval between MR exams was 2–72 months (average 17). Two observers noted size, location, margins, internal and surrounding T1/T2 signal, adjacent disc herniation or bulge, concentric ring, underlying fracture, malignancy, infection, or prior disc surgery, and serial MR changes in these characteristics over time.

Node size averaged 7×9 mm. Most were located at L3 (29%, 24/84), L4 (19%, 16/84) and L2 (13%, 11/84), at the central (39%, 33/84) or outer (30%, 25/84) third of the endplate. 55% (39/71) had a bulging disc, 7% (5/71) had disc herniation. 10% (8/84) had evidence of associated fracture, 17% (14/84) tumor, 7% (6/84) infection. Most nodes had well-defined margins (82%, 69/84). The most common node internal signal was isointense to adjacent disc on T1/T2 (33%, 28/84); surrounding marrow was most commonly hypointense on T1 and hyperintense on T2 (54%, 38/71). A common finding was concentric rings (38%, 32/84) in the marrow surrounding the node, a finding which had 72% negative predictive value for absence of infection, tumor and fracture. On follow-up, there was no interval change in node size in 46%(39/84) of Schmorl’s nodes. 26% (22/84) had increased size. Most (60%, 50/84) showed no temporal change in internal T2 signal. 21% (18/84) of nodes showed decreased internal T2 signal, 13% (11/84) showed increased T2 signal. Regarding the surrounding marrow, most (58%, 49/84) showed no temporal change in T2 signal; 21%(18/84) showed decreased T2 signal, 13% (11/84) showed increased T2 signal. In 13 Schmorl’s nodes with intranodal enhancement, eight (62%) showed no interval change; among eight with enhancement in surrounding marrow, five (63%) showed no change on follow-up.

Although most remain unchanged, a relatively large minority of edematous Schmorl's nodes evolve in size and signal over a relatively short time. Some evolve to form well-defined concentric rings in the surrounding marrow that appear to be analogous to degenerative changes of endplates. Concentric ring formation has a high negative predictive value for “idiopathic” Schmorl’s nodes without underlying fracture, infection, or malignancy.