High Signal Intervertebral Disc in T1W MRI

Dear editor: We present two cases of high signal intervetebral disc in T1-weighted MRI with the differential diagnoses. The first case was a 60-year-old obese man who presented with back pain. The patient underwent an MR examination with a 0.3T permanent scanner (Hitachi, IRIS-II Japan). Spin–echo T1W, T2W images in orthogonal planes and STIR sequences were also obtained (Fig. 1). Hypersignal intensity was demonstrated in T1W and T2W images at the T12–L1 intervertebral disc space. Suppression of this signal was revealed in the STIR sequence (Fig. 2). These findings were compatible with presence of fat in the intervertebral disc space. The second case was a 52-year-old man who presented with splenomegaly, anemia and back pain. Vertebral MRI showed a decreased bone marrow signal in T1W /T2W images with high signal intensity at multilevel intervertebral discs (Fig. 3). The intervertebral disc is a fibrocartilaginous gap between the vertebral bodies which is completely occupied by disc material. It has a centrally located nucleus pulposus and a peripherally located annulus fibrosus. Nucleus pulposus is a semiliquid substance and annulus fibrosus has obliquely arranged connective tissue fibers.1,2 Nucleus pulposus is surrounded by annulus fibrosus which also divides the nucleus by an annular horizontal band resulting in a characteristic biconvex appearance of the adult nucleus pulposus.3 The normal intervertebral disc is intense to muscle on T1W and bright on T2W images. Sometimes, the intervertebral disc appears high signal in T1W images. High signal discs are demonstrated in proliferative and infiltrative bone marrow lesions due to effects of hematopoiesis, iron deposition, fibrosis and tumoral involvement. In these conditions, change in the bone marrow signal leads to reversal of the normal disc/marrow signal, which is prominent in T1W images. As a rule, in T1W images, an increased signal may represent fat, hemorrhage or a paramagnetic substance (melatonin) in melanoma.1 In rare reports, a high signal disc demonstrates calcification and fat deposition or changing. Gadolinium postdiscography MRI should be considered. The pathophysiology of these changes is unknown but here we explain the probable mechanisms of increased intervertebral disc signal intensity on T1W.