Differentiation of osteoporotic and neoplastic vertebral fractures by chemical shift {in-phase and out-of phase} MR imaging

Applying chemical shift images (in-phase/opposed phased) for differentiating low-grade from high-grade glioma and comparison with magnetic resonance spectroscopy

BACKGROUND

Grading gliomas is essential for treatment decisions and patient prognosis. In this study we evaluated the in-phase and out-of-phase sequences for distinguishing high-grade (HGG) from low-grade glioma (LGG) and the correlation with magnetic resonance spectroscopy (MRS) results.

METHODS

This observational study comprised patients with brain tumors referred to our center for brain MRS. The gold standard for diagnosis was based on the World Health Organization (WHO) glioma classification. A standard tumor protocol was accomplished using a 1.5‑T MRS scanner. Before contrast medium administration, extra in- and out-phase sequences were acquired. Three 20-30-mm2 oval regions of interest (ROIs) were placed in the solid component and the signal loss ratio (SLR) was calculated with the following formula: SLR tumor = (SI In phase - SI Opposed phase) / SI In phase Correlations and comparisons between groups were made using the Pearson, chi-square and, independent samples t tests. Receiver operating characteristic (ROC) curve analysis was performed to assess the diagnostic performance. Statistical significance was set at p < 0.05.

RESULTS

In total, 20 patients were included in the LGG and 13 were included in the HGG group. The mean SLR in the HGG and LGG groups was 3.66 ± 2.12 and 1.63 ± 1.86, respectively (p = 0.01). There was a statistically significant correlation between lipid lactate (0.48, p = 0.004) and free lipid (0.44, p = 0.009) concentrations on MRS with SLR.

CONCLUSIONS

The SLR is a simple, rapid, and noninvasive marker for differentiating between LGG and HGG. There is a significant correlation with both the concentration and presence of free lipid and lipid-lactate peaks in MRS.

Magnetic Resonance Imaging Biomarkers of Bone and Soft Tissue Tumors

Magnetic resonance imaging (MRI) is essential in the management of musculoskeletal (MSK) tumors. This review delves into the diverse MRI modalities, focusing on anatomical, functional, and metabolic sequences that provide essential biomarkers for tumor detection, characterization, disease extent determination, and assessment of treatment response. MRI's multimodal capabilities offer a range of biomarkers that enhance MSK tumor evaluation, aiding in better patient management.

Advances in Bone Marrow Imaging: Strengths and Limitations from a Clinical Perspective

Conventional magnetic resonance imaging (MRI) remains the modality of choice to image bone marrow. However, the last few decades have witnessed the emergence and development of novel MRI techniques, such as chemical shift imaging, diffusion-weighted imaging, dynamic contrast-enhanced MRI, and whole-body MRI, as well as spectral computed tomography and nuclear medicine techniques. We summarize the technical bases behind these methods, in relation to the common physiologic and pathologic processes involving the bone marrow. We present the strengths and limitations of these imaging methods and consider their added value compared with conventional imaging in assessing non-neoplastic disorders like septic, rheumatologic, traumatic, and metabolic conditions. The potential usefulness of these methods to differentiate between benign and malignant bone marrow lesions is discussed. Finally, we consider the limitations hampering a more widespread use of these techniques in clinical practice.

Dixon chemical shift MR sequences for demonstrating of bone marrow vertebral metastasis

Background

This study aimed to investigate the diagnostic performance and clinical utility of different MR Dixon sequences in the characterization of vertebral metastasis in a patient with a history of malignant neoplasm and compare the results with 18-F FDG PET CT. Patients were subjected to MR imaging of the dorsal and lumbosacral spine (1.5 T MR machine) using conventional MR, T2 Dixon and T1 post-contrast Dixon.

Results

This study involved 40 patients (45% female and 55% male) with 161 metastatic lesions and median age 61.5 years. The sensitivities of T1 post-contrast water-only (WO), fat-only (FO) and opposed-phase (OP) Dixon for diagnosis of vertebral metastasis were 92.6%, 89.4% and 83.1%, respectively, while the sensitivity of T2 (WO, OP) Dixon was 78.3% with 100% specificity for both T1 and T2 Dixon. There were excellent positive clinical utilities of T1 post-contrast WO (0.925), FO (0.894) and OP (0.826) Dixon with the good positive clinical utility of T2 Dixon (0.783) for lesion finding. There were fair negative clinical utilities of T1 WO (0.636) and FO (0.553) Dixon with poor negative clinical utilities of T1 OP (0.429), T2 WO and OP (0.375) Dixon for lesion screening. 15% was the best in-phase/opposed-phase ratio for differentiation between metastatic and benign vertebral lesions.

Conclusions

MR Dixon techniques are sensitive and specific for the diagnosis of vertebral metastasis. T1 post-contrast and T2 Dixons have excellent and good positive clinical utilities for lesion finding with fair and poor negative clinical utilities for lesion screening, respectively.

Imaging of Bone Marrow: From Science to Practice

The study of the bone marrow may pose important challenges, due to its changing features over the life span, metabolic stress, and in cases of disease or treatment. Bone marrow adipocytes serve as storage tissue, but they also have endocrine and paracrine functions, contributing to local and systemic metabolism.Among different techniques, magnetic resonance (MR) has the benefit of imaging bone marrow directly. The use of advanced MR techniques for bone marrow study has rapidly found clinical applications. Beyond the clinical uses, it has opened up pathways to assess and quantify bone marrow components, establishing the groundwork for further study of its implications in physiologic and pathologic conditions.We summarize the features of the bone marrow as an organ, address the different modalities available for its study, with a special focus on MR advanced techniques and their addition to analysis in recent years, and review some of the challenges in interpreting the appearance of bone marrow.

Hematopoietic islands mimicking osteoblastic metastases within the axial skeleton

BACKGROUND

Hyperplasia of the hematopoietic bone marrow in the appendicular skeleton is common. In contrast, focal hematopoietic islands within the axial skeleton are a rare entity and can confuse with osteoblastic metastases. This study aimed to characterize typical MRI and CT findings of hematopoietic islands in distinction from osteoblastic metastases to help both radiologists and clinicians, on the one hand, not to overdiagnose this entity and, on the other hand, to decide on a reasonable work-up.

METHODS

We retrospectively analyzed the imaging findings of 14 hematopoietic islands of the axial skeleton in ten patients (nine females, median age = 65.5 years [range, 49-74]) who received both MRI and CT at initial diagnosis between 2006 and 2020. CT-guided biopsy was performed in five cases to confirm the diagnosis, while the other five patients received long-term MRI follow-up (median follow-up = 28 months [range, 6-96 months]). Diffusion-weighted imaging was available in three, chemical shift imaging respectively ¹⁸F- fluorodeoxyglucose PET/CT in two, and Technetium 99 m skeletal scintigraphy in one of the patients.

RESULTS

All lesions were small (mean size = 1.72 cm²) and showed moderate hypointense signals on T1- and T2-weighted MRI sequences. They appeared isointense to slightly hyperintense on STIR images and slightly enhanced after gadolinium administration. To differentiate this entity from osteoblastic metastases, CT provides important additional information, as hematopoietic islands do not show sclerosis.

CONCLUSIONS

Hematopoietic islands within the axial skeleton can occur and mimic osteoblastic metastases. However, the combination of MRI and CT allows for making the correct diagnosis in most cases.

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?

Osteoporotic hip and vertebral fractures in the Arab region: a systematic review

Asia is projected to account for the largest proportion of the rising burden of osteoporotic fractures worldwide. Data from the Middle East is scarce. We performed a systematic review on the epidemiology of vertebral and hip osteoporotic fractures in 22 Arab League countries, using Scopus, PubMed, and Embase. We identified 67 relevant publications, 28 on hip and 39 on vertebral fractures. The mean age of patients was 70-74 years, female to male ratio 1.2:2.1. Age-standardized incidence rates, to the UN 2010 population, were 236 to 290/100,000 for women from Kuwait and Lebanon, lower in Morocco. Risk factors for hip fractures included lower BMD or BMI, taller stature, anxiolytics, and sleeping pills. Most patients were not tested nor treated. Mortality derived from retrospective studies ranged between 10 and 20% at 1 year, and between 25 and 30% at 2-3 years. Among 39 studies on vertebral fractures, 18 described prevalence of morphometric fractures. Excluding grade 1 fractures, 13.3-20.2% of women, mean age 58-74 years, had prevalent vertebral fractures, as did 10-14% of men, mean age 62-74 years. Risk factors included age, gender, smoking, multiparity, years since menopause, low BMD, bone markers, high sclerostin, low IgF1, hypovitaminosis D, abdominal aortic calcification score, and VDR polymorphisms. Vertebral fracture incidence in women from Saudi Arabia, mean age 61, was 6.2% at 5 years, including grade 1 fractures. Prospective population-based fracture registries, prevalence studies, predictive models, fracture outcomes, and fracture liaison services from Arab countries are still lacking today. They are the pillars to closing the care gap of this morbid disease.

Differentiation Between Osteoporotic And Neoplastic Vertebral Fractures: State Of The Art And Future Perspectives

Vertebral fractures are a common condition, occurring in the context of osteoporosis and malignancy. These entities affect a group of patients in the same age range; clinical features may be indistinct and symptoms non-existing, and thus present challenges to diagnosis. In this article, we review the use and accuracy of different imaging modalities available to characterize vertebral fracture etiology, from well-established classical techniques, to the role of new and advanced imaging techniques, and the prospective use of artificial intelligence. We also address the role of imaging on treatment. In the context of osteoporosis, the importance of opportunistic diagnosis is highlighted. In the near future, the use of automated computer-aided diagnostic algorithms applied to different imaging techniques may be really useful to aid on diagnosis.

Quantitative Musculoskeletal Tumor Imaging

The role of quantitative magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) techniques continues to grow and evolve in the evaluation of musculoskeletal tumors. In this review we discuss the MRI quantitative techniques of volumetric measurement, chemical shift imaging, diffusion-weighted imaging, elastography, spectroscopy, and dynamic contrast enhancement. We also review quantitative PET techniques in the evaluation of musculoskeletal tumors, as well as virtual surgical planning and three-dimensional printing.

Anomalous signal intensity increase on out-of-phase chemical shift imaging: a manifestation of marrow mineralisation?

OBJECTIVE

In-phase (IP) and out-of-phase (OOP) chemical shift imaging (CSI) is an established technique for clarifying the nature of indeterminate bone marrow lesions, a signal intensity (SI) drop of > 20% at 1.5 tesla (T) or > 25% on 3 T on the OOP sequence being consistent with a non-neoplastic process. Occasionally, SI increase is seen on OOP sequences. The aim of this study is to determine if this is related to marrow sclerosis or matrix mineralisation.

MATERIALS AND METHODS

In 184 cases, the SI change on OOP was calculated. For patients in whom the SI on OOP increased compared with the IP sequence, available CT studies and radiographs were reviewed to look for marrow sclerosis and/or matrix mineralisation.

RESULTS

Forty out of 184 patients (34.25%) showed an anomalous increase in SI on the OOP sequence. CT studies were available in 27 cases (67.5%), of which medullary sclerosis was seen in 20 (74.1%) while matrix mineralisation was seen in a further 2 cases. Review of radiographs demonstrated matrix mineralisation in 6 cases, while punctate signal void consistent with chondral calcification was seen on MRI in 2 more cases. Based on either typical imaging features (n = 22) or histology (n = 18), 7 lesions (17.5%) were classed as non-neoplastic, 18 (45%) as benign neoplasms and 15 (37.5%) as malignant neoplasms.

CONCLUSION

When assessing focal marrow lesions with CSI, anomalous SI increase may be seen on the OOP sequence in approximately one-third of cases. In over 75% of such cases, CT or radiographs demonstrate either diffuse marrow sclerosis or matrix mineralisation.

Assessment of early treatment response on MRI in multiple myeloma: Comparative study of whole-body diffusion-weighted and lumbar spinal MRI

Objectives

To compare remission status at completion of chemotherapy for multiple myeloma (MM) with changes in total diffusion volume (tDV) calculated from whole-body diffusion-weighted imaging (WB-DWI) and fat fraction (FF) of lumbar bone marrow (BM) by modified Dixon Quant (mDixon Quant) soon after induction of chemotherapy, and to assess the predictive value of MRI.

Methods

Fifty patients (mean age, 66.9 ± 10.5 years) with symptomatic myeloma were examined before and after two cycles of chemotherapy. From WB-DWI data, tDV was obtained with the threshold for positive BM involvement. Mean FF was calculated from lumbar BM using the mDixon Quant sequence. At the completion of chemotherapy, patients were categorized into a CR/very good PR (VGPR) group (n = 15; mean age, 67.6 ± 10.3 years) and a PR, SD or PD group (n = 35; mean age, 69.1 ± 8.6 years). ROC curves were plotted to assess performance in predicting achievement of CR/VGPR.

Results

At second examination, serum M protein, β₂-microglobulin, and tDV were significantly decreased and hemoglobin, mean ADC, and FF were significantly increased in the CR/VGPR group and serum M protein was significantly increased in the PR/SD/PD group. The general linear model demonstrated that percentage changes in FF and M protein contributed significantly to achieving CR/VGPR (P = 0.02, P = 0.04, respectively). AUCs of ROC curves were 0.964 for FF and 0.847 for M protein.

Conclusions

Early change in FF of lumbar BM and serum M protein soon after induction of chemotherapy contributed significantly to prediction of CR/VGPR.

The Dixon technique for MRI of the bone marrow

Dixon sequences are established as a reliable MRI technique that can be used for problem-solving in the assessment of bone marrow lesions. Unlike other fat suppression methods, Dixon techniques rely on the difference in resonance frequency between fat and water and in a single acquisition, fat only, water only, in-phase and out-of-phase images are acquired. This gives Dixon techniques the unique ability to quantify the amount of fat within a bone lesion, allowing discrimination between marrow-infiltrating and non-marrow-infiltrating lesions such as focal nodular marrow hyperplasia. Dixon can be used with gradient echo and spin echo techniques, both two-dimensional and three-dimensional imaging. Another advantage is its rapid acquisition time, especially when using traditional two-point Dixon gradient echo sequences. Overall, Dixon is a robust fat suppression method that can also be used with intravenous contrast agents. After reviewing the available literature, we would like to advocate the implementation of additional Dixon sequences as a problem-solving tool during the assessment of bone marrow pathology.

Intravoxel incoherent motion MR imaging for differentiating malignant lesions in spine: A pilot study

PURPOSE

To determine the diagnostic potential of Intravoxel Incoherent Motion (IVIM) MRI for differentiating malignant spinal tumours from acute vertebral compression fractures and tuberculous spondylitis, and to compare IVIM with diffusion-weighted imaging (DWI) and chemical shift imaging (CSI).

METHODS

The Institutional Review Board approved this prospective study, and informed consent was obtained. IVIM MRI, DWI, and CSI at 1.5 T were performed in 25 patients with 12 acute compression fractures, 14 tuberculous spondylitis, and 18 malignant spinal tumours. The parameters of these techniques were assessed using the Kruskal-Wallis test. The diagnostic performance of the parameters was evaluated using receiver operating characteristic (ROC) analysis.

RESULTS

ADC, SIR, D_slow, D_fast, and f values of malignant tumours were significantly different from those of acute compression fracture (for all, p < 0.05). The mean D_slow and D_fast values of malignant spinal tumours had significant differences compared with those of tuberculous spondylitis (for all, p < 0.05). However, no significant differences were observed in any quantitative parameters between the acute compression fracture and the tuberculous spondylitis (p > 0.05). D_slow•f showed the highest AUC value of 0.980 (95%CI: 0.942-1.000) in differentiating acute compression fracture and malignant spinal tumours. D_slow showed the highest AUC value of 0.877 (95%CI: 0.713-0.966) in differentiating tuberculous spondylitis and malignant spinal tumours.

CONCLUSIONS

IVIM MR imaging may be helpful for differentiating malignant spinal tumours from acute vertebral compression fractures and tuberculous spondylitis.

Combined intravoxel incoherent motion diffusion-weighted MR imaging and magnetic resonance spectroscopy in differentiation between osteoporotic and metastatic vertebral compression fractures

Purpose

Our purpose was to combine intravoxel incoherent motion diffusion-weighted MR imaging (IVIM-DWI) and magnetic resonance spectroscopy (MRS) to differentiate osteoporotic fractures from osteolytic metastatic vertebral compression fractures (VCFs).

Methods

A total of 70 patients with VCFs were included and divided into two groups, according to their causes of fractures based on pathological findings or clinical follow-up. All patients underwent conventional sagittal T1WI, T2WI, STIR, IVIM-DWI, and single-voxel MRS. The diffusion coefficient (D), pseudo diffusion (D*), and perfusion fraction (f) parameters from IVIM-DWI and the lipid water ratio (LWR) and fat fraction (FF) parameters from MRS were obtained and compared among groups. Furthermore, the diagnostic performance of MRS, IVIM-DWI, and IVIM-DWI combined with MRS for differentiation between osteoporotic and osteolytic metastatic VCFs was assessed by using receiver operating characteristic (ROC) curve analysis.

Results

Compared with the osteoporotic group, the metastatic group had significantly lower values for f, D, and FF, but higher D* (all P < 0.05). The area under the receiver operating characteristic (ROC) curve of MRS, IVIM-DWI, and IVIM-DWI combined with MRS were 0.73, 0.88, and 0.94, respectively. Among these, the IVIM-DWI combined with MRS showed the highest sensitivity, specificity, and accuracy, which are 90.63% (29/32), 97.37 % (37/38), and 94.29% (66/70), respectively.

Conclusions

IVIM-DWI combined with MRS can be more accurate and efficient for differentiation between osteoporotic and osteolytic metastatic VCFs than single MRS or IVIM-DWI.

Neuroimaging and Stereotactic Body Radiation Therapy (SBRT) for Spine Metastasis

Historically, management options for spinal metastases include surgery for stabilization and decompression and/or external beam radiation therapy (EBRT). EBRT is palliative in nature, as it lacks accurate targeting such that the prescribed radiation doses must be limited in order to maintain safety. Modern advancement in imaging and radiotherapy technology have facilitated the development of stereotactic body radiation therapy (SBRT), which provides increased targeted precision for radiation delivery to tumors resulting in lower overall toxicity, particularly to regional structures such as the spinal cord and esophagus, while delivering higher, more effective, and radically ablative radiation doses.Over the past decade, SBRT has been increasingly utilized as a method of treating spinal metastases either as the primary modality or following surgical intervention in both de novo and reirradiation setting. Numerous studies suggest that SBRT is associated with an 80% to 90% rate of 1-year local control across clinical scenarios. For example, studies of SBRT as the primary treatment modality suggest long-term local control rate of 80% to 95% for spinal metastases. Similarly, SBRT in the adjuvant setting following surgery is associated with local control rates ranging from 70% to 100%. Furthermore, because SBRT allows for lower dose to the spinal cord, it has also been used in patients who have had prior radiation therapy, with studies showing 66% to 93% local control in this scenario.

Efficacy of chemical shift MRI for differentiating diffuse red bone marrow reconversion and hematological malignancies

Background/aim

The main purpose of our study was to determine the efficacy of chemical shift imaging (CSI) for differentiating diffuse red bone marrow reconversion (RBMR) and hematological malignancies. We also aimed to calculate the cut-off value for these entities with similar imaging features in routine magnetic resonance (MR) sequences.

Materials and methods

A total of 54 patients were included: 17 patients (31.4%) with hematological malignancies (group 1), 16 patients (29.6%) with RBMR (group 2), and 21 patients (38.0%) with no clinical and hematological malignancies (control group). Patients with no pathological data or completed two-year follow-up and children were excluded from the study. An experienced radiologist on MRI evaluated the images blindly for final diagnosis. Pathologic results were determined as gold standard. Regions of interests (ROI) were placed on the vertebrae in CSI and signal intensity ratios (SIR) were calculated. The cut-off value was calculated using receiver operating characteristic (ROC) analysis.

Results

SIR values were 0.97 ± 0.16, 0.69 ± 0.31 and 0.28 ± 0.35 (P < 0.001) for GI, G2, and G3, respectively. The cut-off value was 0.82 (P < 0.001). The sensitivity rate was 83.3% (AUC: 58%–96%), specificity was 87% (AUC: 58–98).

Conclusion

CSI may be a valuable diagnostic tool for differentiating diffuse RBMR and hematological malignancies.

Accuracy of Opposed-phase Magnetic Resonance Imaging for the Evaluation of Treated and Untreated Spinal Metastases

RATIONALE AND OBJECTIVES

To assess whether the accuracy of opposed-phase magnetic resonance (MR) imaging to differentiate spinal metastases from benign lesions is influenced by treatment.

MATERIALS AND METHODS

We retrospectively evaluated 25 benign lesions, 25 untreated spinal metastases, and 89 treated spinal metastases in 101 patients who underwent opposed-phase MR spine imaging at our institution. The largest possible region of interest was placed over the lesion in question on out-of-phase and in-phase MR sequences, and the signal intensity ratio (SIR) of the lesions was calculated. The SIRs were compared between benign, untreated, and treated lesions. Receiver operator characteristic (ROC) curves were used to identify the optimal threshold to differentiate benign lesions from untreated spinal metastases, and the accuracy of this threshold was assessed for treated spinal metastases, chemotherapy-treated spinal metastases, and radiated spinal metastases.

RESULTS

Benign lesions had lower mean SIR than untreated (P = 2.4 × 10^-8, 95% confidence interval [0.29, 0.51]) and treated spinal metastases (P = .51; 95% confidence interval [-0.13, 0.06]). A cutoff SIR of 0.856 had an accuracy of 88.00% for untreated lesions, 77.48% for previously treated lesions, and 70.45% for previously radiated lesions. The ROC curve to differentiate benign lesions from radiated spinal metastases was significantly different from the ROC curve to differentiate benign lesions from untreated spinal metastases (P = .0180). The ROC curve to differentiate benign lesions from lesions treated with chemotherapy only was significantly different from the ROC curve to differentiate between benign lesions and radiated spinal metastases (P = .041).

CONCLUSIONS

Opposed-phase imaging is less accurate for treated spinal metastases, in particular after radiation.

The usefulness of chemical-shift magnetic resonance imaging for the evaluation of osteoid osteoma

Objective

The purpose of this study was to determine whether chemical-shift magnetic resonance imaging (MRI) could be useful in the diagnosis of osteoid osteoma when clinical and radiological tumor features are inconclusive.

Materials and Methods

This retrospective study included 17 patients who underwent chemical-shift MRI for the evaluation of osteoid osteoma. For all patients, two musculoskeletal radiologists independently recorded signal intensities on in-phase and out-of-phase images in the nidus of the tumor, in abnormal-intensity bone marrow surrounding the lesion, and in normal-appearing bone marrow. For each region, relative signal intensity ratios were calculated by dividing out-of-phase by in-phase values. Relative ratios > 1 were considered indicative of neoplastic lesions. Statistical analysis was carried out to analyze the sample. Inter-observer and intra-observer agreement for each imaging method were assessed using intraclass correlation coefficients according to the Fleiss method and a value > 0.65 was considered to indicate substantial agreement.

Results

The mean relative signal intensity ratios were 1.2 (range, 0.9-1.4) for the nidus and 0.35 (range, 0.11-0.66) for the surrounding tissue; these values differed significantly from the relative signal-intensity ratios for normal-appearing bone marrow (p < 0.05).

Conclusion

Chemical-shift MRI is useful for the diagnosis and evaluation of osteoid osteoma.

Proton density fat fraction (PDFF) MR imaging for differentiation of acute benign and neoplastic compression fractures of the spine

OBJECTIVES

To evaluate the diagnostic performance of proton density fat fraction (PDFF) magnetic resonance imaging (MRI) to differentiate between acute benign and neoplastic vertebral compression fractures (VCFs).

METHODS

Fifty-seven consecutive patients with 46 acute benign and 41 malignant VCFs were prospectively enrolled in this institutional review board approved study and underwent routine clinical MRI with an additional six-echo modified Dixon sequence of the spine at a clinical 3.0-T scanner. All fractures were categorised as benign or malignant according to either direct bone biopsy or 6-month follow-up MRI. Intravertebral PDFF and PDFF_ratio (fracture PDFF/normal vertebrae PDFF) for benign and malignant VCFs were calculated using region-of-interest analysis and compared between both groups. Additional receiver operating characteristic and binary logistic regression analyses were performed.

RESULTS

Both PDFF and PDFF_ratio of malignant VCFs were significantly lower compared to acute benign VCFs [PDFF, 3.48 ± 3.30% vs 23.99 ± 11.86% (p < 0.001); PDFF_ratio, 0.09 ± 0.09 vs 0.49 ± 0.24 (p < 0.001)]. The areas under the curve were 0.98 for PDFF and 0.97 for PDFF_ratio, yielding an accuracy of 96% and 95% for differentiating between acute benign and malignant VCFs. PDFF remained as the only imaging-based variable to independently differentiate between acute benign and malignant VCFs on multivariate analysis (odds ratio, 0.454; p = 0.005).

CONCLUSIONS

Quantitative assessment of PDFF derived from modified Dixon water-fat MRI has high diagnostic accuracy for the differentiation of acute benign and malignant vertebral compression fractures.

KEY POINTS

• Chemical-shift-encoding based water-fat MRI can reliably assess vertebral bone marrow PDFF • PDFF is significantly higher in acute benign than in malignant VCFs • PDFF provides high accuracy for differentiating acute benign from malignant VCFs.

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)

Bone Marrow Metastases: T2-weighted Dixon Spin-Echo Fat Images Can Replace T1-weighted Spin-Echo Images

Purpose To test the potential of Dixon T2-weighted fat-only sequences to replace T1-weighted sequences for the detection of bone metastases, with the hypothesis that diagnostic performance with an alternative magnetic resonance (MR) imaging protocol (sagittal spin-echo Dixon T2-weighted fat-only and water-only imaging) would not be inferior to that with the standard protocol (sagittal spin-echo T1-weighted and spin-echo Dixon T2-weighted water-only imaging). Materials and Methods A total of 121 consecutive whole-spine MR imaging examinations (63 men; mean age ± standard deviation, 61.4 years ± 11.8) performed for suspected vertebral bone metastases were included in this retrospective, institutional review board-approved study. Quantitative image analysis was performed for 30 randomly selected spine levels. Qualitative analysis was performed separately by two musculoskeletal radiologists, who registered the number of metastases for each spine level. Areas under the curve with the protocols were compared on the basis of nonparametric receiver operating characteristic curve estimations by using a noninferiority test on paired data, with a best valuable comparator as a reference. Interobserver and interprotocol agreement was assessed by using κ statistics. Results Contrast-to-noise ratio was significantly higher on the alternative protocol images than on the standard protocol images (181.1 [95% confidence interval: 140.4, 221.7] vs 84.7 [95% confidence interval: 66.3, 103.1] respectively; P < .001). Diagnostic performance was not significantly inferior with the alternative protocol than with the standard protocol for both readers in a per-patient analysis (sensitivity, 97.9%-98.9% vs 93.6%-97.9%; specificity, 85.2%-92.6% vs 92.6%-96.3%; area under the curve, 0.92-0.96 vs 0.95, respectively; all P ≤ .02) and a per-spine level analysis (all P < .01). Interobserver and interprotocol agreement was good to very good (κ = 0.70-0.81). Conclusion Dixon T2-weighted fat-only and water-only imaging provide, in one sequence, diagnostic performance similar to that of the standard combination of morphologic sequences for the detection of probable spinal bone metastases, thereby providing an opportunity to reduce imaging time by eliminating the need to perform T1 sequences. ^© RSNA, 2017 An earlier incorrect version of this article appeared online. This article was corrected on November 6, 2017.

Differential diagnosis of hemangiomas from spinal osteolytic metastases using 3.0 T MRI: comparison of T1-weighted imaging, chemical-shift imaging, diffusion-weighted and contrast-enhanced imaging

The retrospective study investigated accuracy of quantitative evaluation of T1-weighted imaging (T1WI) with and without fat suppression (FS), chemical-shift, diffusion-weighted imaging (DWI) and enhanced imaging at 3.0 T MRI for distinguishing spinal hemangiomas from metastases. 27 patients with 33 spinal hemangiomas (15 atypical hemangiomas) and 26 patients with 71 metastases were recruited. T1WI, FS T1WI, in- and out-phase, DWI and enhanced T1WI were acquired. Signal intensities (SIs) of lesions were obtained. Signal intensity ratios (SIRs) and enhancement ratios of lesions in enhanced imaging were assessed. Ratio of SI loss of hemangiomas or atypical hemangiomas between T1WI and FS T1WI was higher than those of metastases (p < 0.001). The accuracies of ratio of SI loss between T1WI and FS T1WI for differentiating hemangiomas and atypical hemangiomas from metastases were 96.15% and 91.86%. Ratio of SI loss between in- and out- phase could differentiate hemangiomas and atypical hemangiomas from metastases with accuracies of 74.04% and 84.88%. Cutoff values for hemangiomas in SIRs of ≤ 1.52 (early phase) and ≤ 1.38 (middle phase) yielded accuracies of 92.31% and 82.69%. Enhancement ratios of atypical hemangiomas in middle and delayed phases were higher than that of metastases. Accuracies of apparent diffusion coefficient for differentiating hemangiomas and atypical hemangiomas from metastases were 70.19% and 89.53%. T1WI with and without fat suppression could distinguish spinal hemangiomas from metastases. Quantitative assessment of chemical-shift, DWI and enhanced imaging were helpful to identification of spinal hemangiomas and metastases.

Solid bone tumors of the spine: Diagnostic performance of apparent diffusion coefficient measured using diffusion-weighted MRI using histology as a reference standard

PURPOSE

To assess the diagnostic performance of mean apparent diffusion coefficient (mADC) in differentiating benign from malignant bone spine tumors, using histology as a reference standard. Conventional magnetic resonance imaging (MRI) sequences have good reliability in evaluating spinal bone tumors, although some features of benign and malignant cancers may overlap, making the differential diagnosis challenging.

MATERIALS AND METHODS

In all, 116 patients (62 males, 54 females; mean age 59.5 ± 14.1) with biopsy-proven spinal bone tumors were studied. Field strength/sequences: 1.5T MR system; T₁ -weighted turbo spin-echo (repetition time / echo time [TR/TE], 500/13 msec; number of excitations [NEX], 2; slice thickness, 4 mm), T₂ -weighted turbo spin-echo (TR/TE, 4100/102 msec; NEX, 2; slice thickness, 4 mm), short tau inversion recovery (TR/TE, 4800/89 msec; NEX, 2; slice thickness, 4 mm, IT, 140 msec), axial spin-echo echo-planar diffusion-weighted imaging (DWI) (TR/TE 5200/72 msec; slice thickness 5 mm; field of view, 300; interslice gap, 1.5 mm; NEX, 6; echo-planar imaging factor, 96; no parallel imaging) with b-values of 0 and 1000 s/mm², and 3D fat-suppressed T₁ -weighted gradient-recalled-echo (TR/TE, 500/13 msec; slice thickness, 4 mm) after administration of 0.2 ml/kg body weight gadolinum-diethylenetriamine pentaacetic acid. Two readers manually drew regions of interest on the solid portion of the lesion (hyperintense on T₂ -weighted images, hypointense on T₁ -weighted images, and enhanced after gadolinium administration on fat-suppressed T₁ -weighted images) to calculate mADC. Histology was used as the reference standard. Tumors were classified into malignant primary tumors (MPT), bone metastases (BM), or benign primary tumors (BPT). Statistical tests: Nonnormality of distribution was tested with the Shapiro-Wilk test. The Kruskal-Wallis and Mann-Whitney U-test with Bonferroni correction were used. Sensitivity and specificity of the mADC values for BM, MPT, and BPT were calculated. Approximate receiver operating characteristic curves were created. Interobserver reproducibility was evaluated using the intraclass correlation coefficient (ICC).

RESULTS

The mADC values of MPT (n = 35), BM (n = 65), and BPT (n = 16) were 1.00 ± 0.32 (0.59-2.10) × 10^-3 mm² /s, 1.02 ± 0.25 (0.73-1.96) × 10^-3 mm² /s, 1.31 ± 0.36 (0.83-2.14) × 10^-3 mm² /s, respectively. The mADC was significantly different between BPT and all malignant lesions (BM+MPT) (P < 0.001), BM and BPT (P = 0.008), and MPT and BPT (P = 0.008). No difference was found between BM and MPT (P = 0.999). An mADC threshold of 0.952 × 10^-3 mm² /s yielded 81.3% sensitivity, 55.0% specificity. Accuracy was 76% (95% confidence interval [CI] = 63.9%-88.1%). Interobserver reproducibility was almost perfect (ICC = 0.916; 95% CI = 0.879-0.942).

CONCLUSION

DWI with mADC quantification is a reproducible tool to differentiate benign from malignant solid tumors with 76% accuracy. The mADC values of BPT were statistically higher than that of malignant tumors. However, the large overlap between cases may make mADC not helpful in a specific patient.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1034-1042.

Discrimination between Malignant and Benign Vertebral Fractures Using Magnetic Resonance Imaging

STUDY DESIGN

Retrospective analysis using magnetic resonance imaging (MRI).

PURPOSE

To identify MRI features that could discriminate benign from malignant vertebral fractures.

OVERVIEW OF LITERATURE

Discrimination between benign and malignant vertebral fractures remains challenging, particularly in patients with osteoporosis and cancer. Presently, the most sensitive means of detecting and assessing fracture etiology is MRI. However, published reports have focused on only one or a few discriminators.

METHODS

Totally, 106 patients were assessed by MRI within six weeks of sustaining 114 thoracic and/or lumbar vertebral fractures (benign, n=65; malignant, n=49). The fractures were pathologically confirmed if malignant or clinically diagnosed if benign and were followed up for a minimum of six months. Seventeen features were analyzed in all fractures' magnetic resonance images. Single parameters were analyzed using the chi-square test; a logit model was established using multivariate logistic regression analysis.

RESULTS

The chi-square test revealed 11 malignant and 4 benign parameters. Multivariate logistic regression analysis selected (i) posterior wall diffuse protrusion (odds ratio [OR], 48; 95% confidence interval [CI], 4.2-548; p=0.002), (ii) pedicle involvement (OR, 21; 95% CI, 2.0-229; p=0.01), (iii) posterior involvement (OR, 21; 95% CI, 1.5-21; p=0.02), and (iv) band pattern (OR, 0.047; 95% CI, 0.0005-4.7; p=0.19). The logit model was expressed as P=1/[1+exp (x)], x=-3.88×(i)-3.05×(ii)-3.02×(iii)+3.05×(iv)+5.00, where P is the probability of malignancy. The total predictive value was 97.3%. The only exception was multiple myeloma with features of a benign fracture.

CONCLUSIONS

Although each MRI feature had a different meaning with a variable differentiation power, combining them led to an accurate diagnosis. This study identified the most relevant MRI features that would be helpful in discriminating benign from malignant vertebral fractures.

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.

Quantitative imaging methods in osteoporosis

Osteoporosis is characterized by a decreased bone mass and quality resulting in an increased fracture risk. Quantitative imaging methods are critical in the diagnosis and follow-up of treatment effects in osteoporosis. Prior radiographic vertebral fractures and bone mineral density (BMD) as a quantitative parameter derived from dual-energy X-ray absorptiometry (DXA) are among the strongest known predictors of future osteoporotic fractures. Therefore, current clinical decision making relies heavily on accurate assessment of these imaging features. Further, novel quantitative techniques are being developed to appraise additional characteristics of osteoporosis including three-dimensional bone architecture with quantitative computed tomography (QCT). Dedicated high-resolution (HR) CT equipment is available to enhance image quality. At the other end of the spectrum, by utilizing post-processing techniques such as the trabecular bone score (TBS) information on three-dimensional architecture can be derived from DXA images. Further developments in magnetic resonance imaging (MRI) seem promising to not only capture bone micro-architecture but also characterize processes at the molecular level. This review provides an overview of various quantitative imaging techniques based on different radiological modalities utilized in clinical osteoporosis care and research.

Chemical shift MR imaging in the lumbar vertebra: the effect of field strength, scanner vendors and flip angles in repeatability of signal intensity index measurement

BACKGROUND

To evaluate the reproducibility of signal intensity index (SII) measurements with MRI systems from different vendors and with different field strengths, and to test the effectiveness of flip angle.

METHODS

Thirty-two healthy volunteers (mean age 35.3 ± 9.3 years) were enrolled in this ethics committee-approved study. Chemical shift MR imaging was performed on 1.5- and 3.0-T MR systems from three vendors. Two independent observers measured SII values in five lumbar segments. Inter- and intraobserver agreement was assessed using the interclass correlation coefficients (ICCs). Differences of mean SII values between different field strengths and MR vendors as well as flip angles were compared by using repeated-measures analysis of variance. Differences of mean SII values between different flip angles were also compared by using paired-sample t test.

RESULTS

Inter- and intra-observer correlation coefficients showed good agreement (all ICC > 0.75) when measuring SII values at different MR systems (ICCs ranging from 0.896 to 0.983) and flip angles (ICCs ranging from 0.824 to 0.983). There were no significant differences in mean SII values measured by different MR vendors with different field strengths (all p > 0.05 ranging from 0.337 to 0.824). The differences in the mean SII between the four different flip angles were statistically significant (all p < 0.05 ranging from < 0.001 to 0.004) except the group of flip angle 50° versus 70° (p = 0.116).

CONCLUSION

The SII measurement using chemical shift MR imaging may be comparable between different MR systems. Also high flip angles showed better stability to quantitate lumbar fat content.

Fat fraction estimation of morphologically normal lumbar vertebrae using the two-point mDixon turbo spin-echo MRI with flexible echo times and multipeak spectral model of fat: Comparison between cancer and non-cancer patients

PURPOSE

This study aims to compare fat fraction of lumbar vertebrae between cancer and non-cancer patients, using the two-point modified Dixon (mDixon) turbo spin-echo (TSE) MRI with flexible echo times and multipeak fat spectral model.

MATERIALS AND METHODS

Fat fraction was calculated from fat and water images reconstructed by the mDixon TSE technique. Fat fraction of fat-water phantoms measured with the mDixon TSE method was compared with actual fat percentages. Patients who had undergone mDixon spine MRI and dual-energy X-ray absorptiometry within one year and had no bone metastasis were divided into cancer (n=7) and non-cancer (n=23) groups. Fat fraction and bone mineral density (BMD) were compared between the two groups.

RESULTS

Fat fraction of phantoms measured with mDixon MRI was highly correlated with their actual fat percentages (P<0.01, R(2)=0.93). Fat fraction of lumbar vertebrae was significantly lower in cancer patients (58.27±3.16%) than in non-cancer patients (70.48±1.83%) (P<0.01). BMD was not different between cancer (0.912±0.057g/cm(2)) and non-cancer patients (0.876±0.032g/cm(2)) (P=0.58). Fat fraction and BMD showed no significant correlation (P=0.95, R=0.006).

CONCLUSIONS

A two-point mDixon TSE method for assessing fat fraction was reliable. Fat fraction of morphologically normal lumbar vertebrae was significantly lower in cancer patients compared to non-cancer patients, using the two-point mDixon TSE technique.

Computed Tomography and Magnetic Resonance Imaging in the Differentiation of Osteoporotic Fractures From Neoplastic Metastatic Fractures

Determining whether a low-intensity vertebral fracture in an older person, particularly one with a history of cancer, is due to osteoporosis (OP) or is the result of a metastasis, is a not infrequent clinical problem that has important prognostic and therapeutic implications. The 2 types of fracture are usually indistinguishable on plain radiographs and require higher order imaging for diagnosis. Magnetic resonance imaging is the modality of choice because of its unique ability to depict the bone marrow, which becomes transiently edematous in an acute OP fracture. Preservation of at least part of the normal marrow signal, the visualization of a fracture line parallel to the end plates, the presence of an intravertebral cleft, lack of pedicle involvement, and no extra-osseous mass all favor a benign OP fracture. Absence of the preceding signs, particularly if there is complete replacement of the normal bone marrow and a convex posterior contour of the vertebral body, favors a fracture of malignant origin. Non-routine magnetic resonance sequences using diffusion-weighted imaging and/or chemical shift imaging may be helpful in difficult cases.

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

For now, magnetic resonance (MR) is the best noninvasive imaging modality to evaluate vertebral bone marrow thanks to its inherent soft-tissue contrast and non-ionizing nature. A daily challenging scenario for every radiologist interpreting MR of the vertebral column is discerning the diseased from normal marrow. This requires the radiologist to be acquainted with the used MR techniques to judge the spinal marrow as well as its normal MR variants. Conventional sequences used basically to image marrow include T1W, fat-suppressed T2W and short tau inversion recovery (STIR) imaging provides gross morphological data. Interestingly, using non-routine MR sequences; such as opposed phase, diffusion weighted, MR spectroscopy and contrasted-enhanced imaging; may elucidate the nature of bone marrow heterogeneities; by inferring cellular and chemical composition; and adding new functional prospects. Recalling the normal composition of bone marrow elements and the physiologic processes of spinal marrow conversion and reconversion eases basic understanding of spinal marrow imaging. Additionally, orientation with some common variants seen during spinal marrow MR imaging as hemangiomas and bone islands is a must. Moreover, awareness of the age-associated bone marrow changes as well as changes accompanying different variations of the subject’s health state is essential for radiologists to avoid overrating normal MR marrow patterns as pathologic states and metigate unnecessary further work-up.

Spinal imaging update

The widespread use of MRI has revolutionised the diagnostic process for spinal disorders. A typical protocol for spinal MRI includes T1 and T2 weighted sequences in both axial and sagittal planes. While such an imaging protocol is appropriate to detect pathological processes in the vast majority of patients, a number of additional sequences and advanced techniques are emerging. The purpose of the article is to discuss both established techniques that are gaining popularity in the field of spinal imaging and to introduce some of the more novel ‘advanced’ MRI sequences with examples to highlight their potential uses.

Cite this article: Bone Joint J 2015;97-B:1683–92.

Novel application of chemical shift gradient echo in- and opposed-phase sequences in 3 T MRI for the detection of H-MRS visible lipids and grading of glioma

Objectives

We evaluated the feasibility of using chemical shift gradient-echo (GE) in- and opposed-phase (IOP) imaging to grade glioma.

Methods

A phantom study was performed to investigate the correlation of ¹H MRS-visible lipids with the signal loss ratio (SLR) obtained using IOP imaging. A cross-sectional study approved by the institutional review board was carried out in 22 patients with different glioma grades. The patients underwent scanning using IOP imaging and single-voxel spectroscopy (SVS) using 3T MRI. The brain spectra acquisitions from solid and cystic components were obtained and correlated with the SLR for different grades.

Results

The phantom study showed a positive linear correlation between lipid quantification at 0.9 parts per million (ppm) and 1.3 ppm with SLR (r = 0.79–0.99, p < 0.05). In the clinical study, we found that SLR at the solid portions was the best measure for differentiating glioma grades using optimal cut-points of 0.064 and 0.086 with classification probabilities for grade II (S_II = 1), grade III (S_III = 0.50) and grade IV (S_IV = 0.89).

Conclusions

The results underscore the lipid quantification differences in grades of glioma and provide a more comprehensive characterization by using SLR in chemical shift GE IOP imaging. SLR in IOP sequence demonstrates good performance in glioma grading.

Key Points

• Strong correlation was seen between lipid concentration and SLR obtained using IOP

• IOP sequence demonstrates significant differences in signal loss within the glioma grades

• SLR at solid tumour portions was the best measure for differentiation

• This sequence is applicable in a research capacity for glioma staging armamentarium

Utility of opposed-phase magnetic resonance imaging in differentiating sarcoma from benign bone lesions

PURPOSE

To investigate the utility of opposed-phase magnetic resonance imaging (OP MRI) in differentiating malignant from benign bone lesions.

MATERIALS AND METHODS

MRI scans of musculoskeletal lesions including opposed-phase imaging sequences were reviewed by both an experienced musculoskeletal attending radiologist, and a second year radiology resident. The change in signal from IP to OP images was measured. The reviewers' evaluation of the lesions based on T1 and T2-weighted images was compared to their evaluation with inclusion of the OP sequences.

RESULTS

Twenty-seven lesions in bone were analyzed: 4 malignant primary bone lesions, 3 malignant soft tissue lesions to bone, 3 metastases from visceral malignancies, and 17 benign bone lesions. Benign lesions of bone dropped in signal on OP imaging by an average of 37.1%. Five of the benign lesions decreased in signal by less than 20%, and two increased. Malignant bone lesions dropped in signal by an average of 0.69% with one of the ten lesions showing a greater than 20% drop. When OP sequences were included, concern for malignancy decreased in benign lesions and increased in malignant lesions, for both the resident and attending. Compared with standard MRI, inclusion of these sequences increased the overall confidence in diagnosis for both reviewers.

CONCLUSION

Opposed-phase imaging is helpful in differentiating benign from malignant lesions in bone. Confidence in diagnosis rose for both the attending and the resident as result of the inclusion of OP sequences.

Chemical shift MRI can aid in the diagnosis of indeterminate skeletal lesions of the spine

OBJECTIVES

To evaluate the role of chemical shift MRI in the characterisation of indeterminate skeletal lesions of the spine as benign or malignant.

METHODS

Fifty-five patients (mean age 54.7 years) with 57 indeterminate skeletal lesions of the spine were included in this retrospective study. In addition to conventional MRI at 3 T which included at least sagittal T1WI and T2WI/STIR sequences, patients underwent chemical shift MRI. A cut-off value with a signal drop-out of 20 % was used to differentiate benign lesions from malignant lesions (signal drop-out <20 % being malignant).

RESULTS

There were 45 benign lesions and 12 malignant lesions. Chemical shift imaging correctly diagnosed 33 of 45 lesions as benign and 11 of 12 lesions as malignant. In contrast, there were 12 false positive cases and 1 false negative case based on chemical shift MRI. This yielded a sensitivity of 91.7 %, a specificity of 73.3 %, a negative predictive value of 97.1 %, a positive predictive value of 47.8 % and a diagnostic accuracy of 82.5 %.

CONCLUSIONS

Chemical shift MRI can aid in the characterisation of indeterminate skeletal lesions of the spine in view of its high sensitivity in diagnosing malignant lesions. Chemical shift MRI can potentially avoid biopsy in a considerable percentage of patients with benign skeletal lesions of the spine.

KEY POINTS

• Differentiating benign from malignant skeletal lesions of the spine can be challenging. • Utility of chemical shift MRI in characterising indeterminate spinal lesion is unreported. • This study demonstrates sensitivity 91.7 %, specificity 73.3 %, diagnostic accuracy 82.5 % for CSI. • CSI is useful in differentiating benign from malignant skeletal spine lesions. • Biopsy can potentially be avoided in some patients with benign skeletal lesions.

META: an MRI-based scoring system differentiating metastatic from osteoporotic vertebral fractures

BACKGROUND CONTEXT

Magnetic resonance imaging (MRI) is useful for the differential diagnosis of osteoporotic vertebral fractures (OVFs) and metastatic vertebral fractures (MVFs), but no single finding is absolutely conclusive.

PURPOSE

The purpose of the present study was to create a scoring system to facilitate the correct diagnosis of MVFs by integrating several MRI findings.

STUDY DESIGN

This is a retrospective and single-center observational study that attempts to create a diagnostic scoring system by discriminant analysis.

PATIENTS SAMPLE

We included 100 OVFs and 100 MVFs in thoracolumbar vertebrae of which MR images were obtained within 60 days from the suspected time of fractures.

OUTCOME MEASURES

The sensitivity and specificity of known important MRI findings were assessed, and the classification accuracy of the scoring system was investigated.

METHODS

Seven MRI findings of these fractures were analyzed to evaluate their sensitivity and specificity. Using these findings as variables, discriminant analysis was performed in 140 fractures as a training set, and the classification accuracy was calculated in the remaining 60 fractures as a test set. Additionally, the images of these 60 fractures were reviewed by another blinded reviewer to investigate the interobserver reliability of each finding.

RESULTS

All findings had high specificity with low-to-moderate sensitivity. Eight variables were selected in the final discriminant function. A simpler scoring system (MRI Evaluation Totalizing Assessment [META]) was created by approximating the coefficients and the constant term by integral numbers. The classification accuracy was calculated to be 96.6% in the test set. The interobserver reliability of the key findings varied, but the final discrimination conducted by META had the high agreement between the two reviewers (κ=0.93).

CONCLUSIONS

This novel scoring system, META, could prove to be a useful tool for the differential diagnosis of OVFs and MVFs. It is simple and physician friendly, yet highly accurate.

[Differentiation between acute osteoporotic and metastatic vertebral body fractures by imaging]

OBJECTIVES

This article discusses the morphological criteria for the differentiation between acute osteoporotic and metastatic vertebral body fractures and new imaging methods, such as diffusion-weighted and chemical shift magnetic resonance imaging (MRI) are presented.

BACKGROUND

The differential diagnostics of osteoporotic and metastatic vertebral body fractures can be difficult in some cases. Both entities normally occur without adequate trauma and predominantly in elderly patients.

IMAGING

Conventional X-ray examination is the initial imaging method of choice but is not able to reliably differentiate between the osteoporotic or metastatic etiology of a fracture. Computed tomography (CT) clearly depicts osseous destruction in metastatic fractures but lacks specificity. Magnetic resonance imaging (MRI) shows a higher sensitivity and specificity in differentiating osteoporotic and metastatic fractures.

DIFFERENTIAL DIAGNOSTICS

The combination CT and MRI allows an accurate diagnosis with respect to an osteoprorotic or metastatic etiology in most of cases but bone marrow edema in acute fractures sometimes leads to ambiguous results and differential diagnostic problems.