1645. Utility of CT-Like Bone Contrast Imaging Using Inverted Fast Low Angle Shot (FLASH) MR in Evaluation of Lumbar Degenerative Spine Disease
Authors * Denotes Presenting Author
  1. Karthik Shyam *; Ganga Medical Centre and Hospital
  2. Bhari Thippeswamy Pushpa; Ganga Medical Centre and Hospital
  3. Raksha Algeri; Ganga Medical Centre and Hospital
  4. Rajasekaran S.; Ganga Medical Centre and Hospital
Due to the growing incidence of lumbar degenerative spine disease and related interventions, imaging has become a vital tool in diagnostic and pre-operative assessment. MRI, a mainstay of spine assessment, helps detect degenerative disc disease, whereas CT helps assess related bone changes. These bone changes are key in planning management; however, CT is not advised routinely due to radiation concerns. FLASH sequence of MRI uses T1W-3D-GRE to obtain low bone signal and surrounding high soft-tissue signal, which provides CT-like bone contrast on greyscale inversion. The aim of this study is to evaluate the accuracy of greyscale - inverted FLASH MRI sequences versus CT in diagnosing osseous changes associated with degenerative disc disease.

Materials and Methods:
With institutional review board approval, 148 patients with mechanical low back pain were enrolled in the study. Alongside routine lumbar spine MRI and FLASH sequence, limited CT at the level of the abnormal disc was done. All patients were evaluated for both disc and osseous changes on MRI with FLASH by an experienced radiologist blinded to CT images. Later, a comparison with CT was to evaluate the accuracy of FLASH and routine MRI sequences.

Of the 148 individuals included, age 51 ± 16 years, a total of 201 degenerative discs were assessed. L5-S1 level (45%, n = 91) involvement with Pfirmann grade 4 (61.5%, n = 124) disc change was the most common; 70% (n = 145) discs showed herniation, with 40% (n = 80) associated with spondylolisthesis and 66% (n = 132) with Modic endplate change, of which type 2 was most prevalent (53%, n = 70). With CT as reference, the sensitivity of inverted FLASH imaging in detecting endplate erosion was found to be 95%, marginal osteophytes 94%, corner endplate 97%, annular calcification 93%, intradiscal vacuum phenomenon 92.5%, pars interarticularis defect 100% and facet arthropathy 91%. Significantly improved sensitivity was seen with a combination of T1W, T2W and FLASH in contrast to routine T1W and T2W, assessment alone (>92.5% versus <82%).

The addition of FLASH to routine imaging of degenerative lumbar spine helps detect surgically-relevant bone changes, reducing the need for CT evaluation for the same.