CT-like images based on T1 spoiled gradient-echo and ultra-short echo time MRI sequences for the assessment of vertebral fractures and degenerative bone changes of the spine

Abstract

Objectives To evaluate the performance of 3D T1w spoiled gradient-echo (T1SGRE) and ultra-short echo time (UTE) MRI sequences for the detection and assessment of vertebral fractures and degenerative bone changes compared with conventional CT. Methods Fractures (n = 44) and degenerative changes (n = 60 spinal segments) were evaluated in 30 patients (65 ± 14 years, 18 women) on CT and 3-T MRI, including CT-like images derived from T1SGRE and UTE. Two radiologists evaluated morphological features on both modalities: Genant and AO/Magerl classifications, anterior/posterior vertebral height, fracture age; disc height, neuroforaminal diameter, grades of spondylolisthesis, osteophytes, sclerosis, and facet joint degeneration. Diagnostic accuracy and agreement between MRI and CT and between radiologists were assessed using crosstabs, weighted κ, and intraclass correlation coefficients. Image quality was graded on a Likert scale. Results For fracture detection, sensitivity, specificity, and accuracy were 0.95, 0.98, and 0.97 for T1SGRE and 0.91, 0.96, and 0.95 for UTE. Agreement between T1SGRE and CT was substantial to excellent (e.g., Genant: κ, 0.92 [95% confidence interval, 0.83–1.00]; AO/Magerl: κ, 0.90 [0.76–1.00]; osteophytes: κ, 0.91 [0.82–1.00]; sclerosis: κ, 0.68 [0.48–0.88]; spondylolisthesis: ICCs, 0.99 [0.99–1.00]). Agreement between UTE and CT was lower, ranging from moderate (e.g., sclerosis: κ, 0.43 [0.26–0.60]) to excellent (spondylolisthesis: ICC, 0.99 [0.99–1.00]). Inter-reader agreement was substantial to excellent (0.52–1.00), respectively, for all parameters. Median image quality of T1SGRE was rated significantly higher than that of UTE (p < 0.001). Conclusions Morphologic assessment of bone pathologies of the spine using MRI was feasible and comparable to CT, with T1SGRE being more robust than UTE. Key Points • Vertebral fractures and degenerative bone changes can be assessed on CT-like MR images, with 3D T1w spoiled gradient-echo–based images showing a high diagnostic accuracy and agreement with CT. • This could enable MRI to precisely assess bone morphology, and 3D T1SGRE MRI sequences may substitute additional spinal CT examinations in the future. • Image quality and robustness of T1SGRE sequences are higher than those of UTE MRI for the assessment of bone structures.

Assessment of vertebral fractures and edema of the thoracolumbar spine based on water‐fat and susceptibility‐weighted images derived from a single ultra‐short echo time scan

“…4 Recent studies suggested the use of UTE and zero TE (ZTE) sequences for the depiction of cortical and trabecular bone. [5][6][7] It was further shown that UTE imaging enables the morphological assessment of fractures and degenerative bone changes in the spine 8,9 and joints. 10,11 In addition, susceptibility-weighted imaging (SWI), a technique that uses the different magnetic susceptibilities of tissues, is sensitive to tissues that distort the magnetic field by means of paramagnetic or diamagnetic effects.…”

Comprehensive comparison of dual-energy computed tomography and magnetic resonance imaging for the assessment of bone marrow edema and fracture lines in acute vertebral fractures

“…Finally, results and conclusions are only applicable to the vendor-specific dualsource DECT technique and post-processing software, as well as to the employed imaging protocols, which are routinely used in our department in case of spinal trauma. Particularly in the assessment of fracture lines, alternative MRI protocols could have performed differently, for instance by using diverse slice thickness or sequences such as T1 spoiled gradient-echo or ultra-short echo time sequences, which have recently been shown to provide image quality comparable to CT for the evaluation of certain bone pathologies of the spine [30].…”

3D MRI of the Spine

“…When acquired in 3D, gradient echo imaging can provide "CT-like" high bone-to-soft tissue contrast images with high spatial resolution. 6,7 Zero echo time imaging (ZTE) is a gradient echo sequence that has been applied for bone imaging (►Fig. 2).…”

“…The 3D T1-weighted spoiled gradient-recalled sequences of the lumbar spine acquired at 3 T that were inverted to resemble CT were 97% accurate for fracture detection with substantial to excellent agreement for degenerative findings compared with CT. 6 MR images that even more closely approximate CT can be generated from 3D T1-weighted gradient echo sequences using an image synthesis method based on deep learning (DL). A recent study examining the sacroiliac joints in patients with suspected spondyloarthritis showed that synthetic CT images were more accurate than conventional T1-weighted 2D sequences for detection of erosions, sclerosis, and ankylosis.…”

“…Recent studies describe use of 3D gradient-recalled echo (GRE) sequences to provide "CT-like" bone contrast, obviating the need for CT and its inherent additional cost and radiation exposure. 6,7 Lastly, artifacts common to 2D imaging can be significantly reduced on 3D sequences by virtue of excitation of an entire slab of tissue. Flow artifact from cerebrospinal fluid (CSF) pulsation, prominent in the cervical and thoracic spine, is markedly decreased or rendered absent because the flowing CSF remains in the 3D slab where its signal is detected.…”