Magnetic resonance imaging of the spinal marrow: Basic understanding of the normal marrow pattern and its variant

Preoperative Assessment of Bone Density Using MRI-Based Vertebral Bone Quality Score Modified for Patients Undergoing Cervical Spine Surgery

STUDY DESIGN

Diagnostic accuracy study.

OBJECTIVES

Previous studies have reported the clinical application of the Vertebral Bone Quality (VBQ) scores for assessing bone density in operative lumbar spine patients. We aim to explore whether the method could be modified and applicable for patients undergoing cervical spine surgery.

METHODS

Adult patients receiving cervical spine surgery for degenerative diseases between September 2020 and March 2022 with non-contrast T1-weighted MRI and DEXA were included. Correlation between cervical VBQ scores and DEXA T-scores was analyzed using Pearson's correlation. Student's t test was used to present the discrepancy between the VBQ of patients with normal bone density (T ≥ -1.0) and patients with osteopenia/osteoporosis (T < -1.0). Statistical significance was set at P < .05.

RESULTS

Eighty-three patients (20 patients with T ≥ -1.0 vs 63 patients with T < -1.0 ) were included. Significant difference was found between the cervical VBQ between groups (2.99 ± .79 vs 3.80 ± .81, P < .001). Interclass correlation coefficient for inter-rater reliability was .82 (95% CI: .70-.93) and .91(95% CI: .84-.97) for intra-rater reliability. The area under the ROC curve was .78 (95% CI: .65-.90). The DEXA T-score of the femoral neck, total hip and the lowest DEXA T-score were found to be significantly correlated with the cervical VBQ score according to Pearson correlation analysis (P < .001).

CONCLUSIONS

This is the first study to apply the VBQ method to assess the bone density in preoperative cervical spine patients. Cervical VBQ scores were significantly correlated with DEXA T-score. With an overall accuracy of .78, the radiation-free and cost-effective method could be a potential tool for screening patients with osteopenia and osteoporosis before surgery.

Efficacy of fat quantification methods used in MRI to distinguish between normal, benign, and malignant bone marrow pathologies in children

BACKGROUND

Fat quantification methods in magnetic resonance imaging (MRI) have been studied to differentiate bone marrow pathologies in adult patients; however, scarce literature is available in pediatric patients.

PURPOSE

To evaluate the efficacy of the T1 signal intensity value (T1-SIV), out-of-phase/in-phase signal ratio (OP/IP SR), and fat fraction (FF) to differentiate between normal, benign, and malignant pathological processes.

MATERIAL AND METHODS

A total of 48 pediatric patients with lumbar and pelvic MRI were classified into three groups according to bone marrow pathology (group 1, normal; group 2, benign pathology/reconversion; group 3, malignant). The efficacy of T1-SIV, OP/IP SR, and FF values in differentiating these pathologies was evaluated using Kruskal-Wallis or analysis of variance and followed by Bonferroni or Dunn-Bonferroni tests. Cutoff values for malignant infiltration were defined using ROC analysis.

RESULTS

Although these values were significantly different in all three groups (P = 0.001-0.008), this difference was not sufficient to discriminate between all groups. Subgroup analyses showed significant differences in T1-SIV between groups 1-3, in OP/IP SR between groups 1-3, 2-3, and 1-2, in FF between groups 1-2 and 1-3 in various regions (P = 0.001-0.049). Cutoff values had a sensitivity and specificity of 90%-100% for OP/IP SR and FF.

CONCLUSION

T1-SIV, OP/IP SR, and FF may potentially distinguish normal from pathological bone marrow. OP/IP SR and FF values detected malignant infiltration with high sensitivity and specificity in this study. However, only OP/IP SR may significantly differentiate benign and malignant bone marrow pathologies which needs to be confirmed in the future study with a larger patient population.

Physiological gradient in lumbar spine fat fraction and R2* and its impact on osteoporosis diagnosis

BACKGROUND

Bone marrow adiposity and R2* have been explored as an imaging biomarker for osteoporosis. Chemical shift-encoded MRI (CSE-MRI) is a method that allows for relatively accurate measurement of adiposity and R2* in bone marrow in a simple manner. Additionally, there are reports of a physiological gradient of fat distribution in the lumbar spine. This physiological gradient of fat distribution can potentially impact the prediction of osteoporosis. Furthermore, the distribution of R2* is not well understood.

PURPOSE

This study examined how lumbar spine fat fraction (FF) and R2* change with different levels of the lumbar spine, how they influence osteoporosis prediction, and how they change according to measurement methods.

STUDY DESIGN/SETTING

Cross-sectional study using retrospectively collected data.

PATIENT SAMPLE

The study included patients who underwent dual-energy X-ray absorptiometry and lumbar spine CSE-MRI within one-month intervals between 2017 and 2022.

OUTCOME MEASURES

Reproducibility of FF and R2* based on measurement techniques, changes in FF and R2* according to vertebral level and osteoporosis status, and diagnostic power of osteoporosis based on vertebral level.

METHODS

Patients were categorized into the normal bone density, osteopenia, and osteoporosis groups based on bone mineral density. The relationship between groups and spine level before and after BMD adjustment was investigated using generalized estimating equations. Comparisons between the three groups and various measures of reliability were conducted using intraclass correlation coefficient. The diagnostic performance for predicting osteoporosis was evaluated with a receiver operating characteristic curve.

RESULTS

Comparing the three groups, FF increased with osteoporosis severity, while R2* decreased (p<.001). The intra/inter-rater agreement for FF and R2* was excellent. A physiological gradient within individuals was observed, where FF increased towards the lower lumbar spine (p=.002). R2* tended to decrease, but it was not statistically significant (p=.218). There was no statistically significant difference in the diagnosis of osteoporosis based on FF or R2* across different lumbar spine levels.

CONCLUSIONS

There was an increase in FF and a decrease in R2* from T12 to L5. However, the predictive power of osteoporosis did not significantly differ between each level.

[Imaging Findings of Spinal Metastases with Differential Diagnosis: Focusing on Solitary Spinal Lesion in Older Patients]

If a solitary spinal lesion is found in an older patient, bone metastasis can be primarily considered as the diagnosis. Bone metastasis can occur anywhere, but it mostly occurs in the vertebral body and may sometimes show typical imaging findings, presenting as a single lesion. Therefore, differentiating it from other lesions that mimic bone metastases can be challenging, potentially leading to delayed diagnosis and initiation of primary cancer treatment. This review provides an overview of imaging findings and clinical guidelines for bone metastases and discusses its differences from other diseases that can occur as solitary spinal lesions in older patients.

Evaluating Surgical Cervical Arthrodesis With a Novel MRI Grading Score

STUDY DESIGN

This was a single-institution retrospective study.

OBJECTIVE

Evaluate a magnetic resonance imaging (MRI)-scoring system to differentiate arthrodesis from pseudoarthrosis following anterior cervical discectomy and fusion.

SUMMARY OF BACKGROUND DATA

Diagnostic workup following fusion surgery often includes MRI to evaluate neural structures and computed tomography (CT) and/or dynamic x-rays to evaluate instrumentation and arthrodesis. The use of MRI alone for these evaluations would protect patients from harmful CT and x-ray ionizing radiation.

METHODS

Neurosurgical attending evaluated CTs for arthrodesis or pseudoarthrosis. Blinded neuroradiology attending and neurosurgery senior resident evaluated independent T1 and T2 region of interest (ROI) signal intensity over instrumented disk space. Cerebral spinal fluid (CSF) at the cisterna magnum and distal adjacent uninstrumented vertebral body (VB) were also calculated. ROI interspace /ROI CSF and ROI interspace /ROI VB quotients were used to create T1- and T2-interspace interbody scores (IIS).

RESULTS

Study population (n=64 patients, 50% female) with a mean age of 51.72 years and 109 instrumented levels with 45 fused levels (41.3%) were included. T1-weighted MRI, median T1-IIS CSF for arthrodesis was 176.20 versus 130.92 for pseudoarthrosis ( P <0.0001), T1-IIS VB for arthrodesis was 68.52 and pseudoarthrosis was 52.71 ( P <0.0001). T2-weighted MRI, median T2-IIS CSF for arthrodesis was 27.72 and 14.21 for pseudoarthrosis ( P <0.0001), while T2-IIS VB for arthrodesis was 67.90 and 41.02 for pseudoarthrosis ( P <0.0001). The greatest univariable discriminative capability for arthrodesis via AUROC was T1-IIS VB (0.7743).

CONCLUSION

We describe a novel MRI scoring system that may help determine arthrodesis versus pseudoarthrosis following anterior cervical discectomy and fusion. Postoperative symptomatic patients may only require MRI, which would protect patients from ionizing radiation.

LEVEL OF EVIDENCE

Level IV.

Gut-spine axis: a possible correlation between gut microbiota and spinal degenerative diseases

As society ages, the number of patients with spinal degenerative diseases (SDD) is increasing, posing a major socioeconomic problem for patients and their families. SDD refers to a generic term for degenerative diseases of spinal structures, including osteoporosis (bone), facet osteoarthritis (joint), intervertebral disk degeneration (disk), lumbar spinal canal stenosis (yellow ligament), and spinal sarcopenia (muscle). We propose the term "gut-spine axis" for the first time, given the influence of gut microbiota (GM) on the metabolic, immune, and endocrine environment in hosts through various potential mechanisms. A close cross-talk is noted between the aforementioned spinal components and degenerative diseases. This review outlines the nature and role of GM, highlighting GM abnormalities associated with the degeneration of spinal components. It also summarizes the evidence linking GM to various SDD. The gut-spine axis perspective can provide novel insights into the pathogenesis and treatment of SDD.

Fat fraction quantification of bone marrow in the lumbar spine using the LiverLab assessment tool in healthy adult volunteers and patients with Gaucher disease

BACKGROUND

Magnetic Resonance Imaging is used for evaluation of bone in Gaucher disease (GD), but a widely available quantitative scoring method remains elusive.

AIMS

The study purpose was to assess the reproducibility of the LiverLab tool for assessing bone marrow fat fraction (FF) and determine whether it could differentiate GD patients from healthy subjects.

METHODS

Ten healthy volunteers and 18 GD patients were prospectively recruited. FF was calculated at L3, L4 and L5. GD patient bone marrow burden (BMB) score assessed by one observer. Inter and intra-rater agreement assessed with Bland-Altman data plots. Differences in FF between healthy volunteers versus GD patients and between subjects treated versus not treated assessed using two-sample t-tests. In GD patients, the relationship between FF, BMB and glucosylsphingosine was determined using the Pearson's correlation coefficient.

RESULTS

Healthy volunteer mean FF was 0.36, standard deviation (SD) 0.10 (range 0.20-0.57). Intra and inter-rater SD were both 0.02. GD patient mean FF was 0.40, SD 0.13 (range 0.09-0.57). No statistical difference was shown between healthy volunteers and GD patients (P = 0.447) or between GD patients whether on enzyme replacement therapy or not (P = 0.090). No significant correlation between mean FF and total BMB (r = -0.525, P = 0.253) or between FF and glucosylsphingosine levels (r = 0.287, P = 0.248).

CONCLUSION

Excellent reproducibility of LiverLab FF measurements across studies and observers is comparable to Dixon quantitative chemical shift imaging (QCSI). Lack of statistical difference between GD patients and controls may be explained by limited patient numbers, active treatment or mild disease severity in untreated patients.

Quantitative MRI evaluation of bone marrow in sickle cell disease: relationship with haemolysis and clinical severity

AIM

To evaluate bone marrow fat fraction using the Dixon technique (FFDix) of magnetic resonance imaging (MRI) as a potential biomarker of haemolysis and clinical severity in the overall assessment and follow-up of sickle cell disease (SCD) patients.

MATERIAL AND METHODS

The present study was a cross-sectional study in which healthy individuals and SCD patients (matched for age, sex, and weight) were subjected to MRI of the lumbar spine and pelvis to quantify FFDix in the bone marrow using the Dixon technique. SCD severity was analysed by clinical and laboratory data, and an online calculator. A high degree of haemolysis was defined using the cut-off values haemoglobin (Hb) ≤10 g/dl, lactate dehydrogenase (LDH) ≥325 U/l, reticulocytes ≥3% and total bilirubin (TB) ≥1.2 mg/dl. Pearson's correlation, receiver operating characteristic (ROC) curve and binary logistic regression analysis were performed.

RESULTS

Forty-eight SCD patients (26 homozygous: HbSS and 22 compound heterozygous: HbSC) and 48 healthy individuals participated in the study. FFDix was lower in SCD patients than in the control group, showing even lower values in the HbSS subtype and patients with a higher degree of haemolysis. HbSC patients with a higher degree of haemolysis using hydroxyurea (medium dosage 9.8 mg/kg/day) had lower FFDix. ROC curves and odds ratios for detecting patients with a higher degree of haemolysis at the different FFDix measurement sites demonstrated excellent performance: iliac bones (cut-off ≤16.75%, AUC = 0.824, p<0.001), femoral heads (cut-off ≤46.7%, AUC = 0.775, p=0.001), lumbar vertebrae (cut-off ≤7.8%, AUC = 0.755, p=0.002).

CONCLUSION

Decreased FFDix is indicative of higher degree of haemolysis and SCD severity with great potential as a non-invasive biomarker contributing to the overall assessment and follow-up of SCD patients.

Imaging of bone marrow pitfalls with emphasis on MRI

Normal marrow contains both hematopoietic/red and fatty/yellow marrow with a predictable pattern of conversion and skeletal distribution on MRI. Many variations in normal bone marrow signal and appearances are apparent and the reporting radiologist must differentiate these from other non-neoplastic, benign or neoplastic processes. The advent of chemical shift imaging has helped in characterising and differentiating more focal heterogeneous areas of red marrow from marrow infiltration. This review aims to cover the MRI appearances of normal marrow, its evolution with age, marrow reconversion, variations of normal marrow signal, causes of oedema-like marrow signal, and some common non-neoplastic entities, which may mimic marrow neoplasms.

Differential immune landscapes in appendicular versus axial skeleton

Roughly 400,000 people in the U.S. are living with bone metastases, the vast majority occurring in the spine. Metastases to the spine result in fractures, pain, paralysis, and significant health care costs. This predilection for cancer to metastasize to the bone is seen across most cancer histologies, with the greatest incidence seen in prostate, breast, and lung cancer. The molecular process involved in this predilection for axial versus appendicular skeleton is not fully understood, although it is likely that a combination of tumor and local micro-environmental factors plays a role. Immune cells are an important constituent of the bone marrow microenvironment and many of these cells have been shown to play a significant role in tumor growth and progression in soft tissue and bone disease. With this in mind, we sought to examine the differences in immune landscape between axial and appendicular bones in the normal noncancerous setting in order to obtain an understanding of these landscapes. To accomplish this, we utilized mass cytometry by time-of-flight (CyTOF) to examine differences in the immune cell landscapes between the long bone and vertebral body bone marrow from patient clinical samples and C57BL/6J mice. We demonstrate significant differences between immune populations in both murine and human marrow with a predominance of myeloid progenitor cells in the spine. Additionally, cytokine analysis revealed differences in concentrations favoring a more myeloid enriched population of cells in the vertebral body bone marrow. These differences could have clinical implications with respect to the distribution and permissive growth of bone metastases.

Gut-disc axis: A cause of intervertebral disc degeneration and low back pain?

PURPOSE

Low back pain (LBP), a widely prevalent and costly disease around the world, is mainly caused by intervertebral disc (IVD) degeneration (IDD). Although numerous factors may trigger this degenerative process, microbiome dysbiosis has recently been implicated as one of the likely causes. However, the exact relationship between the microbiome and IDD is not well understood. This review summarizes the potential mechanisms and discusses microbiome dysbiosis's possible influence on IDD and LBP.

METHODS

Prospective literature review.

RESULTS

Alterations in microbiome composition and host responses to the microbiota causing pathological bone development and involution, led to the concept of gut-bone marrow axis and gut-bone axis. Moreover, the concept of the gut-disc axis was also proposed to explain the microbiome's role in IDD and LBP. According to the existing evidence, the microbiome could be an important factor for inducing and aggravating IDD through changing or regulating the outside and inside microenvironment of the IVD. Three potential mechanisms by which the gut microbiota can induce IVD and cause LBP are: (1) translocation of the bacteria across the gut epithelial barrier and into the IVD, (2) regulation of the mucosal and systemic immune system, and (3) regulation of nutrient absorption and metabolites formation at the gut epithelium and its diffusion into the IVD. Furthermore, to investigate whether IVD is initiated by pathogenic bacteria and establish the correlation between the presence of certain microbial groups with the disease in question, microbiome diversity analysis based on16S rRNA data can be used to characterise stool/blood microbiota from IVD patients.

CONCLUSION

Future studies on microbiome, fungi and viruses in IDD is necessary to revolutionize our thinking about their possible role in the development of IVD diseases. Furthermore, we believe that inflammation inhibition and interruption of amplification of cascade reaction in IVD by targeting the gut and IVD microbiome is worthwhile for the treatment of IDD and LBP.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Imaging for Plasma Cell Dyscrasias: What, When, and How?

Imaging plays a vital role in the diagnosis, response assessment, and follow-up of patients with plasma cell bone disease. The radiologic diagnostic paradigm has thus far evolved with developing technology and availability of better imaging platforms; however, the skewed availability of these imaging modalities in developed vis-à-vis the developing countries along with the lack of uniformity in reporting has led to a consensus on the imaging criteria for diagnosing and response assessment in plasma cell dyscrasia. Therefore, it is imperative for not only the radiologists but also the treating oncologist to be aware of the criteria and appropriate imaging modality to be used in accordance with the clinical question. The review will allow the treating oncologist to answer the following questions on the diagnostic, prognostic, and predictive abilities of various imaging modalities for plasma cell dyscrasia: a) What lesions can look like multiple myeloma (MM) but are not?; b) Does the patient have MM? To diagnose MM in a high-risk SMM patient with clinical suspicion, which modality should be used and why?; c) Is the patient responding to therapy on follow-up imaging once treatment is initiated?; d) To interpret commonly seen complications post-therapy, when is it a disease and when is the expected sequel to treatment? Fractures, red marrow reconversion?; and e) When is the appropriate time to flag a patient for further workup when interpreting MRI spine done for back pain in the elderly? How do we differentiate between commonly seen osteoporosis-related degenerative spine versus marrow infiltrative disorder?

Diffuse vertebral marrow changes at MRI: Multiple myeloma or normal?

Five MRI patterns of marrow involvement (diffuse, focal, combined diffuse and focal, variegated, and normal) are observed in patients with a marrow proliferative disorder including MM. The wide range of marrow involvement patterns in monoclonal plasma cell proliferative disorders mirrors that of their natural histories that can vary from indolent to rapidly lethal. MRI of the axial bone marrow contributes to stage these disorders, but it should not be obtained for disease detection and characterization because of its limited specificity and sensitivity. At MRI, diffuse benign hematopoietic marrow hyperplasia and marrow heterogeneities in elderly patients mimic the diffuse and variegated patterns observed in MM patients. Careful analysis of fat- and fluid-sensitive MR images and quantitative marrow assessment by using MRI and FDG-PET can contribute in differentiating these changes from those associated with neoplastic marrow infiltration, with some residual overlapping findings.

Imaging findings of granulocyte colony-stimulating factor-producing tumors: a case series and review of the literature

Granulocyte colony-stimulating factor (G-CSF)-producing tumors have an aggressive clinical course. Here, we report five cases of G-CSF-producing tumors and review the literature, focusing on imaging findings related to tumor-produced G-CSF. In addition to our cases, we identified 30 previous reports of G-CSF-producing tumors on which ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET)/CT, bone scintigraphy, or evaluation of bone marrow MR findings was performed. White blood cell count, serum C-reactive protein, and serum interleukin-6 were elevated in all cases for which these parameters were measured. G-CSF-producing tumors presented large necrotic masses (mean diameter 83.2 mm, range 17–195 mm) with marked FDG uptake (mean maximum standardized uptake value: 20.09). Diffuse FDG uptake into the bone marrow was shown in 28 of the 31 cases in which FDG-PET/CT was performed. The signal intensity of bone marrow suggested marrow reconversion in all seven MRI-assessable cases. Bone scintigraphy demonstrated no significant uptake, except in two cases with bone metastases. Splenic FDG uptake was increased in 8 of 10 cases in which it was evaluated. These imaging findings may reflect the effects of tumor-produced G-CSF. The presence of G-CSF-producing tumors should be considered in patients with cancer who show these imaging findings and marked inflammatory features of unknown origin.

Axial Spondyloarthritis: Mimics and Pitfalls of Imaging Assessment

Axial spondyloarthritis (axSpA) is a chronic inflammatory disorder that predominantly involves the axial skeleton. Imaging findings of axSpA can be divided into active changes, which include bone marrow edema, synovitis, enthesitis, capsulitis, and intra-articular effusion, and structural changes, which include erosions, sclerosis, bone fatty infiltration, fat deposition in an erosion cavity, and bone bridging or ankylosis. The ability to distinguish between imaging lesions suggestive of axSpA and artifacts or lesions suggestive of other disorders is critical for the accurate diagnosis of axSpA. Diagnosis may be challenging, particularly in early-stage disease and magnetic resonance imaging (MRI) plays a key role in the detection of subtle or inflammatory changes. MRI also allows the detection of structural changes in the subchondral bone marrow that are not visible on conventional radiography and is of prognostic and monitoring value. However, bone structural changes are more accurately depicted using computed tomography. Conventional radiography, on the other hand, has limitations, but it is easily accessible and may provide insight on gross changes as well as rule out other pathological features of the axial skeleton. This review outlines the imaging evaluation of axSpA with a focus on imaging mimics and potential pitfalls when assessing the axial skeleton.

Differentiation of Vertebral Metastases From Focal Hematopoietic Marrow Depositions on MRI: Added Value of Proton Density Fat Fraction

OBJECTIVE. The purpose of this study was to evaluate the added value of proton density fat fraction (PDFF) in differentiating vertebral metastases from focal hematopoietic marrow depositions. MATERIALS AND METHODS. The study included 44 patients with 30 vertebral metastases and 14 focal hematopoietic marrow depositions who underwent spinal MRI. The final diagnoses were based on histologic confirmation, follow-up MRI, or PET/CT. Two musculoskeletal radiologists with 1 and 15 years of experience independently interpreted both image sets (i.e., images from conventional MRI alone versus images from conventional MRI and PDFF combined). Using a 5-point scale, the readers scored their confidence in the malignancy of the vertebral lesions. The diagnostic performance (AUC) of the two image sets was assessed via ROC curve analyses. Sensitivities, specificities, and accuracies (for both image sets) were compared using the McNemar test. Kappa coefficients were calculated to assess interobserver agreement. RESULTS. Both readers showed improved diagnostic performance after PDFF was added (AUC, 0.840-0.912 and 0.805-0.895 for readers 1 and 2, respectively). However, adding PDFF did not significantly improve the sensitivity and specificity of either reader (p > .05). Interobserver agreement significantly improved from moderate (κ = 0.563) to excellent (κ = 0.947) after PDFF was added. CONCLUSION. The addition of PDFF to a conventional MRI protocol improved the diagnostic performance for differentiating vertebral metastases from focal hematopoietic marrow depositions but without resulting in significant improvement in sensitivity and specificity.

Dual-energy CT in musculoskeletal trauma

Dual-energy computed tomography (DECT) combines the advantages of conventional CT with the ability to detect bone marrow oedema (BMO), which was previously limited to magnetic resonance imaging (MRI). By analysing DECT virtual non-calcium (VNCa) maps, radiologists can improve the detection of subtle and occult fractures and approximate the acuity/healing of fractures of indeterminate age. This review highlights the role of DECT in the assessment of musculoskeletal trauma, particularly among elderly, post-menopausal women and those at risk for osteoporosis. DECT is especially useful in investigating trabecular bone predominant regions (e.g., vertebral bodies, pelvis, hip, and long bone metaphyses) for stress (i.e., fatigue or insufficiency) and fragility fractures. CT is often performed first due to its increased availability, especially in the emergency setting, shorter imaging duration, and possible patient contraindications to magnetic resonance imaging (MRI). By enabling BMO detection, DECT may have a role in triaging patients for definitive MRI assessment. Understanding the role of anatomical, pathological, and patient factors in image interpretation can improve radiologist adoption of DECT, increase diagnostic confidence, and improve patient management.

Confounding factors in multi-parametric q-MRI protocol: A study of bone marrow biomarkers at 1.5 T

OBJECT

The MRI tissue characterization of vertebral bone marrow includes the measurement of proton density fat fraction (PDFF), T₁ and T₂* relaxation times of the water and fat components (T_1W, T_1F, T₂*_W, T₂*_F), IVIM diffusion D, perfusion fraction f and pseudo-diffusion coefficient D*. However, the measurement of these vertebral bone marrow biomarkers (VBMBs) is affected with several confounding factors. In the current study, we investigated these confounding factors including the regional variation taking the example of variation between the anterior and posterior area in lumbar vertebrae, B₁ inhomogeneity and the effect of fat suppression on f.

MATERIALS AND METHODS

A fat suppressed diffusion-weighted sequence and two 3D gradient multi-echo sequences were used for the measurements of the seven VBMBs. A turbo flash B₁ map sequence was used to estimate B₁ inhomogeneities and thus, to correct flip angle for T₁ quantification. We introduced a correction to perfusion fraction f measured with fat suppression, namely f_PDFF.

RESULTS

A significant difference in the values of PDFF, f and f_PDFF, T_1F, T₂*_W and D was observed between the anterior and posterior region. Although, little variations of flip angle were observed in this anterior-posterior direction in one vertebra but larger variations were observed in head-feet direction from L1 to L5 vertebrae.

DISCUSSION

The regional difference in PDFF, f_PDFF and T₂*_W can be ascribed to differences in the trabecular bone density and vascular network within vertebrae. The regional variation of VBMBs shows that care should be taken in reproducing the same region-of-interest location along a longitudinal study. The same attention should be taken while measuring f in fatty environment, and measuring T₁. Furthermore, the MRI-protocol presented here allows for measurements of seven VBMBs in less than 6 min and is of interest for longitudinal studies of bone marrow diseases.

Bone marrow magnetic resonance imaging: physiologic and pathologic findings that radiologist should know

Magnetic resonance imaging (MRI) plays a leading role in the non-invasive evaluation of bone marrow (BM). Normal BM pattern depends on the ratio and distribution of yellow and red marrow, which are subject to changes with age, pathologies, and treatments. Neonates show almost entirely red marrow. Over time, yellow marrow conversion takes place with a characteristic sequence leading to a red marrow persistence in proximal metaphyses of long bones. In adults, normal BM is composed of both red (40% water, 40% fat) and yellow marrow (15% water, 80% fat). Due to the higher content of fat, yellow marrow normally appears hyperintense on T1-weighted (T1w) fast spin echo (FSE) sequences and hypo-/iso-intense in short tau inversion recovery (STIR) T2-weighted (T2w); red marrow appears slightly hyperintense in T1w FSE and hyper-/iso-intense in STIR T2w. Pathologic BM has reduced fat and increased water percentages, resulting hypointense in T1w FSE and hyperintense in STIR T2w. In oncologic patients, BM MRI signal largely depends on the treatment (irradiation and/or chemotherapy) and its timing. BM fat and water amount and location in normal red/yellow and pathologic marrow are responsible for different signals in MRI sequences whose knowledge by radiologists may help to differentiate between normal and pathologic findings. Our aim was to discuss and illustrate the MRI of BM physiologic conversion and pathologic reconversion occurring in malignancies and after treatments in cancer patients.

Focal nodular marrow hyperplasia: Imaging features of 53 cases

OBJECTIVE

To describe the characteristic imaging features of focal nodular marrow hyperplasia (FNMH).

METHODS AND MATERIALS

Retrospective review of all patients with a diagnosis of FNMH between January 2007 and September 2019.

RESULTS

The study included 53 patients, 7 males and 46 females with a mean age of 58 years (range 12-95 years). All had MRI with conventional spin echo sequences showing a poorly defined round/oval lesion with mild T₁W iso/hyperintensity compared to skeletal muscle, low T₂W turbo spin echo (TSE) signal intensity (SI) compared to marrow fat and variable SI on STIR, but never associated with reactive marrow oedema. All 53 patients had follow-up MRI, with all lesions remaining stable or partially resolving. In-phase (IP) and out-of-phase (OP) chemical shift imaging (CSI) was obtained in 31 of these, with 28 (90.3%) showing >20% SI drop on the OP sequence, while 3 (9.7%) demonstrated <20% SI drop. CT was available in 26 cases, 17 (65.4%) showing mild medullary sclerosis. Single-photon emission computed tomography CT (SPECT-CT) was available in four cases and Flourodeoxyglucose positron emission tomography CT (FDG PET-CT) in 2, all showing increased uptake. Focal uptake was also seen in three of eight patients who had undergone whole body bone scintigraphy. Only one lesion was biopsied, confirming FNMH.

CONCLUSION

The imaging appearances of FNMH have been described on various modalities, particularly MRI with emphasis on the role of IP and OP CSI typically demonstrating >20% SI reduction. FNMH should be recognised and treated as a 'do not touch' lesion which does not require biopsy or prolonged follow-up.

ADVANCES IN KNOWLEDGE

We describe and clarify the imaging characteristics of FNMH on MRI, including CSI, CT and various nuclear medicine modalities. An imaging algorithm is suggested for allowing a non-invasive diagnosis.

Vertebral Bone Quality Score and Postoperative Lumbar Lordosis Associated with Need for Reoperation After Lumbar Fusion

BACKGROUND

Poor bone quality is a known risk factor for hardware failure and adjacent segment disease after lumbar fusion. One new method of analyzing bone quality is the vertebral bone quality (VBQ) score, which can be obtained from preoperative lumbar magnetic resonance imaging (MRI) scans. We decided to evaluate whether patients' VBQ scores were associated with reoperation after lumbar fusion.

METHODS

We queried records of patients who underwent elective lumbar fusion for degenerative conditions between 2012 and 2017. Patients who required reoperations after lumbar fusions because of symptomatic hardware failure or adjacent segment disease were combined into a case group and compared with a matched control group.

RESULTS

Of the 46 patients who underwent elective lumbar fusions and required reoperation, 30 met the inclusion criteria. A 2:1 control group of 60 individually age-, body mass index-, and sex-matched patients who did not require reoperation was then created. The reoperation group had significantly lower degrees of postoperative lumbar lordosis. There were no significant differences regarding other spinopelvic parameters, adjacent Pfirrmann scores, or dual energy x-ray absorptiometry (DXA) T scores. There was, however, a significant difference in VBQ scores between the groups, with the reoperation group having a higher VBQ score.

CONCLUSIONS

This study found that bone quality, according to the VBQ score rather than the DXA T score, is an important risk factor for reoperation after lumbar fusion surgery. Therefore, this MRI-based tool may be used to assist surgeons in preoperative planning for spine surgeries with the goal of reducing the risk of requiring reoperation.

A novel MRI-based score assessing trabecular bone quality to predict vertebral compression fractures in patients with spinal metastasis

OBJECTIVE

Vertebral compression fractures (VCFs) in patients with spinal metastasis can lead to destabilization and often carry a high risk profile. It is therefore important to have tools that enable providers to predict the occurrence of new VCFs. The most widely used tool for bone quality assessment, dual-energy x-ray absorptiometry (DXA), is not often available at a patient's initial presentation and has limited sensitivity. While the Spinal Instability Neoplastic Score (SINS) has been associated with VCFs, it does not take patients' baseline bone quality into consideration. To address this, the authors sought to develop an MRI-based scoring system to estimate trabecular vertebral bone quality (VBQ) and to assess this system's ability to predict the occurrence of new VCFs in patients with spinal metastasis.

METHODS

Cases of adult patients with a diagnosis of spinal metastasis, who had undergone stereotactic body radiation therapy (SBRT) to the spine or neurosurgical intervention at a single institution between 2012 and 2019, were retrospectively reviewed. The novel VBQ score was calculated for each patient by dividing the median signal intensity of the L1-4 vertebral bodies by the signal intensity of cerebrospinal fluid (CSF). Multivariable logistic regression analysis was used to identify associations of demographic, clinical, and radiological data with new VCFs.

RESULTS

Among the 105 patients included in this study, 56 patients received a diagnosis of a new VCF and 49 did not. On univariable analysis, the factors associated with new VCFs were smoking status, steroid use longer than 3 months, the SINS, and the novel scoring system-the VBQ score. On multivariable analysis, only the SINS and VBQ score were significant predictors of new VCFs and, when combined, had a predictive accuracy of 89%.

CONCLUSIONS

As a measure of bone quality, the novel VBQ score significantly predicted the occurrence of new VCFs in patients with spinal metastases independent of the SINS. This suggests that baseline bone quality is a crucial factor that requires assessment when evaluating these patients' conditions and that the VBQ score is a novel and simple MRI-based measure to accomplish this.

A study of dynamic contrast-enhanced MR imaging features and influence factors of pelvic bone marrow in adult females

Perfusion of the pelvic bone marrow is reduced in the postmenopausal group and with age. Quantitative dynamic contrast-enhanced MRI could reflect the blood supply characteristics and hemodynamic changes of the pelvic bone marrow. These results contribute to the description of osteoporosis in the postmenopausal females and the elderly.

INTRODUCTION

To investigate the effect of menstrual status and age on the perfusion of pelvic bone marrow in adult females using quantitative dynamic contrast-enhanced MRI (DCE-MRI).

METHODS

In total, 96 adult females who underwent DCE-MRI between September 2017 and December 2017 were included. All the subjects' quantitative DCE-MRI parameters of pelvic bone marrow were measured and retrospectively analyzed, including K^trans (volume transfer constant), K_ep (efflux rate constant), and V_e (interstitial volume). According to their menstrual status, the subjects were divided into a premenopausal group (n = 39) and a postmenopausal group (n = 57), and the two groups were then divided into four subgroups according to age. The intraobserver reliability was assessed by the intraclass correlation coefficient (ICC). The parameters were compared between different menstrual status groups and age subgroups by Mann-Whitney test, and Spearman correlation analysis was used to evaluate the correlation between the age and the quantitative parameters.

RESULTS

The ICCs of the K^trans, K_ep, and V_e values were 0.989, 0.974, and 0.920, respectively. K^trans, K_ep, and V_e of the premenopausal group were significantly higher than those of the postmenopausal group (P < 0.05). The overall age was negatively correlated with K^trans, K_ep, and V_e (r = - 0.590, - 0.357, and - 0.381, respectively, P < 0.05). In the premenopausal group, K^trans and V_e were significantly higher in subgroup 1 (≤ 40 years) compared with subgroup 2 (> 40 years) (P < 0.05), and age showed a negative correlation with K^trans and V_e (r = - 0.344 and - 0.334, respectively, P < 0.05). In the postmenopausal group, K^trans and K_ep were significantly higher in subgroup 3 (≤ 60 years) compared with subgroup 4 (> 60 years) (P < 0.05), and age showed a negative correlation with K^trans and K_ep (r = - 0.460 and - 0.303, respectively, P < 0.05).

CONCLUSION

Menstrual status and age have significant effects on the perfusion of the pelvic bone marrow microenvironment in adult females and that the microenvironment of the pelvic bone marrow displays different changes at different age stages. Quantitative DCE-MRI has contributed to the interpretation of the pelvic bone marrow perfusion status.

Sensitivity and specificity assessment of DWI and ADC for the diagnosis of osteoporosis in postmenopausal patients

OBJECTIVE

In this study, we prospectively investigated the diagnostic capability of diffusion-weighted magnetic resonance imaging (DWI) in assessing vertebral marrow changes in postmenopausal women with osteoporosis.

MATERIALS AND METHODS

Sixty postmenopausal women (mean age 60.2 ± 6.11 years) underwent both dual-energy X-ray absorptiometry (DEXA) of the spine and MRI. Results were acquired from each patient's L2 to L4, for a total of 180 lumbar vertebrae. Based on bone mineral density (BMD) measurements obtained from DEXA, the vertebrae were divided into three groups as follows: normal (n = 52), osteopenic (n = 92), and osteoporotic (n = 36). DWI of the vertebral body was performed to assess the apparent diffusion coefficient (ADC). The ADC outcomes were compared among the three groups and correlated with BMD.

RESULTS

ADC values (× 10^-6 mm²/s) were significantly lower in the osteoporotic group (135.67 ± 44.10) in comparison to the normal group (561.85 ± 190.37) (P = 0.0001). The results showed a positive correlation between ADC and BMD values (r = 0.748, P = 0.0001). In receiver operating characteristic (ROC) analysis, the area under the curve for DWI was 0.912 (P = 0.001). A cut-off value of 400 mm²/s for the diagnosis of osteoporosis; had sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 90.90%, 83.34%, 88.89%, 93.75%, and 76.93%, respectively.

CONCLUSION

ADC values correlated positively with BMD in women. DWI can allow quantitative evaluation of bone marrow changes and osteoporosis in postmenopausal women.

Lumbar muscle and vertebral bodies segmentation of chemical shift encoding-based water-fat MRI: the reference database MyoSegmenTUM spine

Background

Magnetic resonance imaging (MRI) is the modality of choice for diagnosing and monitoring muscular tissue pathologies and bone marrow alterations in the context of lower back pain, neuromuscular diseases and osteoporosis. Chemical shift encoding-based water-fat MRI allows for reliable determination of proton density fat fraction (PDFF) of the muscle and bone marrow. Prior to quantitative data extraction, segmentation of the examined structures is needed. Performed manually, the segmentation process is time consuming and therefore limiting the clinical applicability. Thus, the development of automated segmentation algorithms is an ongoing research focus.

Construction and content

This database provides ground truth data which may help to develop and test automatic lumbar muscle and vertebra segmentation algorithms. Lumbar muscle groups and vertebral bodies (L1 to L5) were manually segmented in chemical shift encoding-based water-fat MRI and made publically available in the database MyoSegmenTUM. The database consists of water, fat and PDFF images with corresponding segmentation masks for lumbar muscle groups (right/left erector spinae and psoas muscles, respectively) and lumbar vertebral bodies 1–5 of 54 healthy Caucasian subjects. The database is freely accessible online at https://osf.io/3j54b/?view_only=f5089274d4a449cda2fef1d2df0ecc56.

Conclusion

A development and testing of segmentation algorithms based on this database may allow the use of quantitative MRI in clinical routine.

Apparent diffusion coefficient of vertebral haemangiomas allows differentiation from malignant focal deposits in whole-body diffusion-weighted MRI

OBJECTIVES

The aim of this study was to identify apparent diffusion coefficient (ADC) values for typical haemangiomas in the spine and to compare them with active malignant focal deposits.

METHODS

This was a retrospective single-institution study. Whole-body magnetic resonance imaging (MRI) scans of 106 successive patients with active multiple myeloma, metastatic prostate or breast cancer were analysed. ADC values of typical vertebral haemangiomas and malignant focal deposits were recorded.

RESULTS

The ADC of haemangiomas (72 ROIs, median ADC 1,085×10-6mm2s-1, interquartile range 927-1,295×10-6mm2s-1) was significantly higher than the ADC of malignant focal deposits (97 ROIs, median ADC 682×10-6mm2s-1, interquartile range 583-781×10-6mm2s-1) with a p-value < 10-6. Receiver operating characteristic (ROC) analysis produced an area under the curve of 0.93. An ADC threshold of 872×10-6mm2s-1 separated haemangiomas from malignant focal deposits with a sensitivity of 84.7 % and specificity of 91.8 %.

CONCLUSIONS

ADC values of classical vertebral haemangiomas are significantly higher than malignant focal deposits. The high ADC of vertebral haemangiomas allows them to be distinguished visually and quantitatively from active sites of disease, which show restricted diffusion.

KEY POINTS

• Whole-body diffusion-weighted MRI is becoming widely used in myeloma and bone metastases. • ADC values of vertebral haemangiomas are significantly higher than malignant focal deposits. • High ADCs of haemangiomas allows them to be distinguished from active disease.

Magnetic Resonance Imaging correlates of benign and malignant alterations of the spinal bone marrow

Background and aim of the work: Bone marrow (BM) abnormalities in the spine are a common, sometimes unexpected, finding on Magnetic Resonance Imaging (MRI), which is the most sensitive imaging modality to evaluate the marrow, and their interpretation can be difficult for the unexperienced radiologist. In this review, the MRI appearance of normal age-related BM changes, as well as the imaging features of benign and malignant diseases, are presented. Discussion: A large variety of BM signal alterations has been identified and described, including normal variants, BM reconversion, degenerative changes, infections, spondyloarthritis and osteonecrosis, trauma, neoplastic lesions (both primary or metastatic), post-radiation and chemotherapy sequelae. Conclusions: Knowledge of normal age-related BM appearance, normal variants and patterns of involvement in focal and diffuse bone diseases is essential, together with clinical and laboratory data, to narrow the list of the possible differential diagnoses. The radiologist should be familiar with these signal changes, as they can sometimes be discovered incidentally. In this context, it is equally important not to attribute pathological significance to benign alterations and to promptly detect signs of malignant diseases. (www.actabiomedica.it)

Utility of 111In-Cl3 scintigraphy for differentiating bone marrow reconversion

Indium chloride (111In-Cl3) scintigraphy has been used to evaluate various hematological diseases for many years. However, there have been few reports on patients with bone marrow reconversion showing high uptake in 111In-Cl3 scintigraphy. Herein, we report a case of a 68-year-old man with esophageal cancer who underwent 18F-FDG PET/CT for staging of the disease. 18F-FDG PET/CT demonstrated high uptake in the first lumbar vertebral body, which was difficult to distinguish bone metastasis and bone marrow reconversion. 111In-Cl3 scintigraphy demonstrated specific findings with high uptake in the lesion, indicating bone marrow hyperplasia or reconversion.

Quantitative MRI and spectroscopy of bone marrow

Bone marrow is one of the largest organs in the human body, enclosing adipocytes, hematopoietic stem cells, which are responsible for blood cell production, and mesenchymal stem cells, which are responsible for the production of adipocytes and bone cells. Magnetic resonance imaging (MRI) is the ideal imaging modality to monitor bone marrow changes in healthy and pathological states, thanks to its inherent rich soft‐tissue contrast. Quantitative bone marrow MRI and magnetic resonance spectroscopy (MRS) techniques have been also developed in order to quantify changes in bone marrow water–fat composition, cellularity and perfusion in different pathologies, and to assist in understanding the role of bone marrow in the pathophysiology of systemic diseases (e.g. osteoporosis). The present review summarizes a large selection of studies published until March 2017 in proton‐based quantitative MRI and MRS of bone marrow. Some basic knowledge about bone marrow anatomy and physiology is first reviewed. The most important technical aspects of quantitative MR methods measuring bone marrow water–fat composition, fatty acid composition, perfusion, and diffusion are then described. Finally, previous MR studies are reviewed on the application of quantitative MR techniques in both healthy aging and diseased bone marrow affected by osteoporosis, fractures, metabolic diseases, multiple myeloma, and bone metastases.

Level of Evidence: 3

Technical Efficacy: Stage 2

J. Magn. Reson. Imaging 2018;47:332–353.

Pathophysiology of Bone Fragility in Patients with Diabetes

It has been well established that bone fragility is one of the chronic complications of diabetes mellitus, and both type 1 and type 2 diabetes are risk factors for fragility fractures. Diabetes may negatively affect bone health by unbalancing several pathways: bone formation, bone resorption, collagen formation, inflammatory cytokine, muscular and incretin system, bone marrow adiposity and calcium metabolism. The purpose of this narrative review is to explore the current understanding of pathophysiological pathways underlying bone fragility in diabetics. In particular, the review will focus on the peculiar cellular and molecular system impairment that may lead to increased risk of fracture in type 1 and type 2 diabetes.

Serous degeneration of bone marrow mimics spinal tumor

OBJECTIVE

To present a rare case of serous degeneration of bone marrow which resembles primary spinal tumor or bony metastasis to spine. Serous degeneration of bone marrow or gelatinous marrow transformation is a rare disease characterized by focal marrow hypoplasia, fat atrophy, and accumulation of extracellular mucopolysaccharides abundant in hyaluronic acid. Few literature was reviewed and few clinical case was presented.

METHODS

Two cases of serous marrow transformation were reported.

RESULTS

In the first case, a 29-year-old man suffered from severe left buttock pain. Bone metastasis was impressed in radiology examinations. Percutaneous endoscopic lumbar discectomy was performed along with bone biopsy. In the second case, a 49-year-old man presented lower back pain with radiation to bilateral lower legs. Magnetic resonance imaging revealed a water-like signal lesion in sacrum. Serous marrow transformation was confirmed pathologically in both cases.

CONCLUSION

To the best of our knowledge, a case of serous degeneration of bone marrow resembling malignancy has not been reported in the literature. In this report, two cases demonstrate serous transformation of bone marrow mimics spinal tumor.