Differentiation of Predominantly Osteoblastic and Osteolytic Spine Metastases by Using Susceptibility-weighted MRI

Abstract

To evaluate the use of susceptibility-weighted MRI for the differentiation of predominantly osteoblastic and osteolytic spine metastases. Materials and Methods: For this prospective study, 53 study participants (mean age, 54.5 years 6 14.3 [range, 22-88 years]; 27 men with a mean age of 55.3 years 6 12.7 [range, 22-72 years] and 26 women with a mean age of 53.8 years 6 15.7 [range, 23-88 years]) with clinically suspected spine metastases underwent imaging with standard MRI sequences, susceptibility-weighted MRI, and CT. Sensitivities and specificities of MRI sequences for the detection of predominantly osteoblastic and osteolytic metastases were determined by using CT as the reference standard. The metastases-to-vertebral body signal intensity ratio (MVR) was calculated to compare modalities. Phantom measurements were obtained to correlate bone densities between MRI sequences and CT. Results: A total of 64 metastases (38 predominantly osteoblastic, 26 predominantly osteolytic) were detected. Susceptibilityweighted MRI achieved a sensitivity of 100% (38 of 38) and specificity of 96% (25 of 26) for predominantly osteoblastic metastases and a sensitivity of 96% (25 of 26) and specificity of 100% (38 of 38) for predominantly osteolytic metastases. Standard MRI sequences achieved a sensitivity of 89% (34 of 38) and specificity of 73% (19 of 26) for predominantly osteoblastic metastases and a sensitivity of 73% (19 of 26) and specificity of 92% (35 of 38) for predominantly osteolytic metastases. MVR measurements obtained with susceptibility-weighted MRI demonstrated a strong correlation with those obtained with CT (R 2 = 0.75), whereas those obtained with T1-weighted MRI, T2-weighted MRI, and turbo inversion-recovery magnitude MRI showed a weak to moderate correlation (R 2 = 0.00, R 2 = 0.35, and R 2 = 0.39, respectively). Susceptibility-weighted MRI showed a strong correlation with CT with regard to metastases size (R 2 = 0.91). In phantom measurements, susceptibility-weighted MRI enabled the reliable differentiation of different degrees of mineralization (R 2 = 0.92 compared with CT). Conclusion: Susceptibility-weighted MRI enables the reliable differentiation between predominantly osteoblastic and osteolytic spine metastases with a higher accuracy than standard MRI sequences.

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

“…12 Recently, SWI was extended to other regions of the body: as calcified structures are diamagnetic, allowing SWI to visualize the calcified bone matrix. [13][14][15][16][17][18] SWI could, thus, be a promising technique to enhance the contrast of osseous tissue components. Second, Dixon sequences are commonly used in the clinical routine either for fat suppression or to generate water-and fat-separated images and to assess soft-tissue components.…”

Value of susceptibility-weighted imaging for the assessment of angle measurements reflecting hip morphology

“…SWMR is a 3D gradient-echo(GRE)-technique, which can visualise calcified structures like the calcified bone matrix [10][11][12][13] . SWMR is sensitive to substances, which distort the magnetic field, like paramagnetic or diamagnetic substances.…”

Preconditioned water‐fat total field inversion: Application to spine quantitative susceptibility mapping

“…The scans were read in a consensus-like setting and the readers were strictly blinded to the reports created during the clinical routine and to the characteristics of the metastases (osteolytic/ osteoblastic) similiar to. 7 First, the CT images were evaluated via consensus reading in order to provide the reference standard for osteolytic and osteoblastic metastases. After an interval of about four weeks to avoid recall bias, the conventional MR sequences (T1w TSE, T2w IP, T2w water) and the QSM sequence results were separately evaluated for differentiating metastases between osteolytic and osteoblastic.…”

“…In the reading of the conventional MR sequences, metastases that were predominantly hypointense on T1-weighted images and hyperintense on T2-weighted images were classified as osteolytic, and, conversely, metastases that were predominantly hypointense on T1-and T2-weighted images were classified as predominantly osteoblastic. 7 In the reading of the QSM maps, metastases were graded as osteoblastic if they were hypointense on MIP across echo times and hypointense on the QSM map, and, conversely, metastases that were hyperintense in the MIP and neutral on the QSM map (values around zero) were classified as osteolytic. The diagnostic confidence of the QSM methods to distinguish between osteolytic and osteoblastic changes was graded as 1 (low confidence), 2 (medium confidence), or 3 (high confidence).…”