Measurement Techniques and Utility of Hounsfield Unit Values for Assessment of Bone Quality Prior to Spinal Instrumentation

Zaidi, Qasim; Danisa, Olumide; Cheng, Wayne K.

doi:10.1097/brs.0000000000002813

Cited by 146 publications

(124 citation statements)

References 18 publications

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“…26,27 However, many authors have advocated that CT HU values can serve as a potential proxy to DXA given the moderate correlation between HU values and osteoporosis. 5,7,9,10,28 Another reason that HUs on preoperative CT are valuable as opposed to DXA is that it can be readily measured on the PACS, a system that nearly all modern medical centers use. For instance, in our study, 93 of 138 patients who underwent single-level LLIF had preoperative CT scans, but only 12 of 138 patients had a DXA scan before surgery.…”

Section: Discussionmentioning

confidence: 99%

“…Zaidi et al have shown correlation between HU values and success of lumbar fusions. 28 Mi et al showed that in patients undergoing transforaminal lumbar interbody fusion with unilateral pedicle screw fixation, lower HU values were significantly associated with subsidence (113.4 vs 127.9 HUs, p < 0.05). 4 To our knowledge, there is very limited literature published about HUs and subsidence in LLIF.…”

Section: Discussionmentioning

confidence: 99%

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The association between lower Hounsfield units on computed tomography and cage subsidence after lateral lumbar interbody fusion

Mummaneni²,

Wang³

et al. 2020

Neurosurgical Focus

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OBJECTIVEOne vexing problem after lateral lumbar interbody fusion (LLIF) surgery is cage subsidence. Low bone mineral density (BMD) may contribute to subsidence, and BMD is correlated with Hounsfield units (HUs) on CT. The authors investigated if lower HU values correlated with subsidence after LLIF.METHODSA retrospective study of patients undergoing single-level LLIF with pedicle screw fixation for degenerative conditions at the University of California, San Francisco, by 6 spine surgeons was performed. Data on demographics, cage parameters, preoperative HUs on CT, and postoperative subsidence were collected. Thirty-six–inch standing radiographs were used to measure segmental lordosis, disc space height, and subsidence; data were collected immediately postoperatively and at 1 year. Subsidence was graded using a published grade of disc height loss: grade 0, 0%–24%; grade I, 25%–49%; grade II, 50%–74%; and grade III, 75%–100%. HU values were measured on preoperative CT from L1 to L5, and each lumbar vertebral body HU was measured 4 separate times.RESULTSAfter identifying 138 patients who underwent LLIF, 68 met the study inclusion criteria. All patients had single-level LLIF with pedicle screw fixation. The mean follow-up duration was 25.3 ± 10.4 months. There were 40 patients who had grade 0 subsidence, 15 grade I, 9 grade II, and 4 grade III. There were no significant differences in age, sex, BMI, or smoking. There were no significant differences in cage sizes, cage lordosis, and preoperative disc height. The mean segmental HU (the average HU value of the two vertebrae above and below the LLIF) was 169.5 ± 45 for grade 0, 130.3 ± 56.2 for grade I, 100.7 ± 30.2 for grade II, and 119.9 ± 52.9 for grade III (p < 0.001). After using a receiver operating characteristic curve to establish separation criteria between mild and severe subsidence, the most appropriate threshold of HU value was 135.02 between mild and severe subsidence (sensitivity 60%, specificity 92.3%). After univariate and multivariate analysis, preoperative segmental HU value was an independent risk factor for severe cage subsidence (p = 0.017, OR 15.694, 95% CI 1.621–151.961).CONCLUSIONSLower HU values on preoperative CT are associated with cage subsidence after LLIF. Measurement of preoperative HU values on CT may be useful when planning LLIF surgery.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The association between lower Hounsfield units on computed tomography and cage subsidence after lateral lumbar interbody fusion

Mummaneni²,

Wang³

et al. 2020

Neurosurgical Focus

View full text Add to dashboard Cite

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“…Li et al (16) recommended that radiologists examine and report osteoporosis on routine abdominal CT. In addition, Zaidi et al (17)noted that HU value measurement is a useful and practical technique for assessing bone quality that could be reported by a radiologist in all patients with preexisting abdominal CT scans. Pickhardt et al (18), in their comprehensive series using CT and DXA, determined that their threshold values for osteoporosis at vertebrae L1 to T12 ranged from 110 to 120 HU, whereas normal vertebral density was determined as 200 HU or higher.…”

Section: Discussionmentioning

confidence: 99%

The association of reduced bone density with paraspinal muscle atrophy and adipose tissue in geriatric patients: a cross-sectional CT study

Ekin¹

2019

Turk J Med Sci

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This is a retrospective cohort study. Ethics committee approval was obtained for the study. All patients aged 65 years and over who underwent abdominal CT for any reason between October 2017 and July 2018 were sequentially included in the study. Patients who were diagnosed with an intraabdominal mass, intraabdominal widespread free fluid, ileus, vertebral tumor, vertebral fracture, or large herniation on the anterior wall of the abdomen were excluded from the study. Background/aim: The aim of the study is to examine the relationship among bone density, adipose tissue, and muscle mass with abdominal CT in geriatric patients. Materials and methods: The study is a retrospective cohort study of patients 65 years and over who underwent abdominal CT for any reason between October 2017 and July 2018. Third lumbar vertebra density, fatty degeneration of the paraspinal muscle, subcutaneous adipose tissue, and mesenteric adipose tissue ratio were evaluated. Results: A total of 312 patients, 144 females and 168 males, were included in the study. Reduced bone density was found in 237 (76%) patients. Reduced bone density and muscle atrophy was more frequent in females (P < 0.001). Muscle atrophy was found to occur 5.7 times more frequently in cases of reduced bone density (OR, 95% CI = 5.74 (3.27-10.09), P < 0.001). There was no significant relationship found between reduced bone density and subcutaneous adipose tissue thickness or mesenteric adipose tissue ratio (P = 0.073, P = 0.939, respectively). Conclusion: In the geriatric age group, reduced bone density and muscle atrophy were quite common and were significantly more frequent in women. Furthermore, a strong association between reduced bone density and muscle atrophy was found. No relationship was found between reduced bone density and subcutaneous adipose tissue thickness-mesenteric adipose ratio.

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“…36 However, previous studies have focused on the lumbar spine, establishing thresholds of 135 HU for osteopenic spines, 120 HU for the risk of pedicle screw loosening, 110 HU for osteoporotic spines, and 90 HU for the risk of vertebral body fracture. 32,37,38 Although these numbers may be useful in identifying osteoporosis in patients undergoing spinal surgery for degenerative pathology, the same correlation has not been clearly shown in patients undergoing ASD correction, especially at the UIV in the thoracic spine. 39 Thus, in ASD patients, the HUs of the LT spine may be more critical than the HUs of the lumbar spine.…”

Section: Discussionmentioning

confidence: 99%

The association between lower Hounsfield units of the upper instrumented vertebra and proximal junctional kyphosis in adult spinal deformity surgery with a minimum 2-year follow-up

Duan

Mummaneni²,

Rivera³

et al. 2020

Neurosurgical Focus

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OBJECTIVEPatients undergoing long-segment fusions from the lower thoracic (LT) spine to the sacrum for adult spinal deformity (ASD) correction are at risk for proximal junctional kyphosis (PJK). One mechanism of PJK is fracture of the upper instrumented vertebra (UIV) or higher (UIV+1), which may be related to bone mineral density (BMD). Because Hounsfield units (HUs) on CT correlate with BMD, the authors evaluated whether HU values were correlated with PJK after long fusions for ASD.METHODSThe authors performed a retrospective study of patients older than 50 years who had undergone ASD correction from the LT spine to the sacrum in the period from October 2007 to January 2018 and had a minimum 2-year follow-up. Demographic and spinopelvic parameters were measured. HU values were measured on preoperative CT at the UIV, UIV+1, and UIV+2 (2 levels above the UIV) levels and were assessed for correlations with PJK.RESULTSThe records of 127 patients were reviewed. Fifty-four patients (19 males and 35 females) with a mean age of 64.91 years and mean follow-up of 3.19 years met the study inclusion criteria; there were 29 patients with PJK and 25 patients without. There was no statistically significant difference in demographics or follow-up between these two groups. Neither was there a difference between the groups with regard to postoperative pelvic incidence (PI), sacral slope (SS), lumbar lordosis (LL), PI minus LL (PI-LL), thoracic kyphosis (TK), or sagittal vertical axis (SVA; all p > 0.05). Postoperative pelvic tilt (p = 0.003) and T1 pelvic angle (p = 0.014) were significantly higher in patients with PJK than in those without. Preoperative HUs at UIV, UIV+1, and UIV+2 were 120.41, 124.52, and 129.28 in the patients with PJK, respectively, and 152.80, 155.96, and 160.00 in the patients without PJK, respectively (p = 0.011, 0.02, and 0.018). Three receiver operating characteristic (ROC) curves for preoperative HU values at the UIV, UIV+1, and UIV+2 as a predictor for PJK were established, with areas under the ROC curve of 0.710 (95% CI 0.574–0.847), 0.679 (95% CI 0.536–0.821), and 0.681 (95% CI 0.539–0.824), respectively. The optimal HU value by Youden index was 104 HU at the UIV (sensitivity 0.840, specificity 0.517), 113 HU at the UIV+1 (sensitivity 0.720, specificity 0.517), and 110 HU at the UIV+2 (sensitivity 0.880, specificity 0.448).CONCLUSIONSIn patients undergoing long-segment fusions from the LT spine to the sacrum for ASD, PJK was associated with lower HU values on CT at the UIV, UIV+1, and UIV+2. The measurement of HU values on preoperative CTs may be a useful adjunct for ASD surgery planning.

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Measurement Techniques and Utility of Hounsfield Unit Values for Assessment of Bone Quality Prior to Spinal Instrumentation

Abstract: 4.

Cited by 146 publications

References 18 publications

The association between lower Hounsfield units on computed tomography and cage subsidence after lateral lumbar interbody fusion

The association between lower Hounsfield units on computed tomography and cage subsidence after lateral lumbar interbody fusion

The association of reduced bone density with paraspinal muscle atrophy and adipose tissue in geriatric patients: a cross-sectional CT study

The association between lower Hounsfield units of the upper instrumented vertebra and proximal junctional kyphosis in adult spinal deformity surgery with a minimum 2-year follow-up

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