Intravoxel incoherent motion diffusion-weighted magnetic resonance imaging of focal vertebral bone marrow lesions: initial experience of the differentiation of nodular hyperplastic hematopoietic bone marrow from malignant lesions

Assessment of chemical-shift and diffusion-weighted magnetic resonance imaging in differentiating malignant and benign vertebral lesions in oncologic patients. A single institution experience

BACKGROUND

To analyze the contribution of two non-standard magnetic resonance imaging (MRI) techniques the chemical-shift image (CSI), and diffusion-weighted imaging (DWI) in distinguishing malignant and benign vertebral bone marrow lesions (VBMLs).

PATIENTS AND METHODS

Conventional spine MRI protocol, followed by CSI and DWI was performed with a 1.5 T system on 102 oncologic patients between January 2020 and December 2023. From the identified 325 VBMLs, 102 representative lesions (one per patient) were selected. VBMLs were divided into malignant (n = 74) and benign (n = 28) based on histopathology, or imaging follow-up. The quantitative parameters for VBMLs assessment were signal intensity ratio (SIR) derived from CSI and apparent diffusion coefficient (ADC) derived from DWI.

RESULTS

The malignant VBMLs had significantly higher SIR values (p < 0.05) and lower ADC values compared to benign VBMLs (p < 0.05). The area under the curve (AUC) was 0.953 (p < 0.001) for SIR, and 0.894 for ADC (p < 0.001) (cut-off at > 0.82, and ≤ 1.57x10-3 mm2/s, respectively). The sensitivity and specificity for SIR were 93.6%, and 88.5%, while for ADC were 88.2% and 92.3% (respectively). The combined use of SIR and ADC improved the diagnostic accuracy to AUC of 0.988 (p < 0.001, cut-off at > 0.19), sensitivity, and specificity of 100.0% and 90.9% (respectively).

CONCLUSIONS

Quantitative parameters, SIR and ADC, derived from two non-standard MRI techniques, CSI, and DWI, showed diagnostic strength in differentiating malignant and benign VBMLs. Combining both methods can further enhance the diagnostic performance and accuracy of spine MRI in clinical practice.

Incidence, epidemiology, radiology, and classification of metastatic spine tumors: WFNS Spine Committee recommendations

Spinal metastasis (SMs) are the most encountered tumors of the spine. Their occurrence is expected roughly around one to two years after primary tumor diagnosis. Since the advent of Magnetic Resonance Imaging (MRI), this technology has been considered the gold standard for SMs diagnosis and characterization due to its precise ability to comprehend the rate of soft tissue compression/invasion (dural sac/nervous tissue), which is one of the main drivers of management strategies. Computed Tomography (CT) remains unbeatable when a detailed bony anatomy and instability assessment is searched. Nuclear medicine technologies may have a role in diagnosis when standard MR or CT study findings are inconclusive or when the extent of the systemic metastatic disease is studied. The main objective of this study is to offer an update on the epidemiology and radiology of spinal metastasis (SMs), endorsed by the WFNS Spine Committee. A systematic review of the literature of the last ten years gave 1531 results with "spine/spinal metastatic tumors/metastasis AND radiology OR imaging OR classification" as search strings in all fields, of which 56 papers were fully analyzed. The results were discussed and voted on in two consensus meetings of the WFNS (World Federation of Neurosurgical Societies) Spine Committee, reaching a positive or negative consensus using the Delphi method. The committee stated nine recommendations on two main topics: (1) Incidence and epidemiology of SMs; (2) Radiology and classifications of SMs.

Age-related T1 mapping, fat fraction, diffusion and perfusion parameters of the lumbar vertebrae in healthy children under 3.0 T MRI

AIM

Compare the T1 mapping, fat fraction, diffusion and perfusion parameters of the lumbar vertebrae of different age groups to establish normal values for healthy children and observe the trends in these parameters with age.

MATERIALS AND METHODS

A total of 146 healthy children (0-14 years) were included in this prospective study and underwent 3.0 T lumbar MRI examination. The study cohort was divided into five age groups (Group A ∼ E) according to development milestones in children. T1 mapping, Dixon and IVIM (intravoxel incoherent motion)sequence images were used to measure the parameters of lumbar vertebrae 2-4.

RESULTS

The normal values of each parameter were measured and compared across different age groups. The T1 value was negatively correlated with age (r=-0.619, p<0.001). The fat fraction (FF%) was positively correlated with age (r=0.635, p<0.001). There was a negative correlation between the D value and age (r=-0.406, p<0.001). The D∗ value was positively correlated with age (r=0.54, p<0.001). The f value was positively correlated with age (r=0.775, p<0.001). The inflexion points of the T1 value and FF% curves were at approximately 3 years old (36 months).The inflexion points of the IVIM-related parameter curves were approximately 5 years old (60 months).

CONCLUSION

The age-dependent differences in the vertebral body parameters of this pediatric cohort suggest changes in the bone marrow composition and cellular structure of the vertebral body during physiological growth in children. The establishment of normal values of children's lumbar spine can facilitate the clinical study of diseases.

Intravoxel Incoherent Motion Factors Affecting Collapse and Nonunion of Osteoporotic Vertebral Fracture

STUDY DESIGN

Longitudinal study.

OBJECTIVES

Intravoxel incoherent motion (IVIM), a magnetic resonance imaging (MRI) scanning technique that applies diffusion-weighted imaging (DWI), is effective for the quantitative assessment of malignant tumors of the vertebral bone. We hypothesized that IVIM parameters of vertebral bodies are associated with the prognosis of osteoporotic vertebral fracture (OVF). We aimed to explore the relationships between IVIM parameters for vertebral collapse and non-union after OVF and calculate the cut-off values of these parameters for vertebral collapse and non-union.

METHODS

A total of 150 patients with acute OVF (150 women; mean age: 79.1 ± 7.4 years) were included and treated conservatively with bracing. MRI was performed at the time of injury. IVIM parameters, such as apparent diffusion coefficient (ADC), molecular diffusion coefficient (D), and perfusion-related diffusion (D*) were recorded. The patients were classified into 3 groups: low-collapse (height loss of ≤50%), high-collapse (height loss of >50%), and non-union. We compared ADC, D, and D* among the low-collapse, high-collapse, and non-union groups and performed a receiver operating characteristic (ROC) curve analysis to determine the boundary values of the high-collapse and non-union groups.

RESULTS

The low-collapse, high-collapse, and non-union groups had no significant differences in ADC and D. However, D* differed significantly among the 3 groups. ROC analysis revealed cut-off values of 19.0 × 10-3 mm2/s and 12.3 × 10-3 mm2/s for the high-collapse and non-union groups, respectively.

CONCLUSIONS

D* is a significant prognostic indicator for high-collapse and non-union groups with OVF. This suggests that D* should be considered when assessing OVF.

IDEAL-IQ combined with intravoxel incoherent motion diffusion-weighted imaging for quantitative diagnosis of osteoporosis

BACKGROUND

Osteoporosis (OP) is a common chronic metabolic bone disease characterized by decreased bone mineral content and microstructural damage, leading to increased fracture risk. Traditional methods for measuring bone density have limitations in accurately distinguishing vertebral bodies and are influenced by vertebral degeneration and surrounding tissues. Therefore, novel methods are needed to quantitatively assess changes in bone density and improve the accurate diagnosis of OP.

METHODS

This study aimed to explore the applicative value of the iterative decomposition of water and fat with echo asymmetry and least-squares estimation-iron (IDEAL-IQ) sequence combined with intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) for the diagnosis of osteoporosis. Data from 135 patients undergoing dual-energy X-ray absorptiometry (DXA), IDEAL-IQ, and IVIM-DWI were prospectively collected and analyzed. Various parameters obtained from IVIM-DWI and IDEAL-IQ sequences were compared, and their diagnostic efficacy was evaluated.

RESULTS

Statistically significant differences were observed among the three groups for FF, R2*, f, D, DDC values, and BMD values. FF and f values exhibited negative correlations with BMD values, with r=-0.313 and - 0.274, respectively, while R2*, D, and DDC values showed positive correlations with BMD values, with r = 0.327, 0.532, and 0.390, respectively. Among these parameters, D demonstrated the highest diagnostic efficacy for osteoporosis (AUC = 0.826), followed by FF (AUC = 0.713). D* exhibited the lowest diagnostic performance for distinguishing the osteoporosis group from the other two groups. Only D showed a significant difference between genders. The AUCs for IDEAL-IQ, IVIM-DWI, and their combination were 0.74, 0.89, and 0.90, respectively.

CONCLUSIONS

IDEAL-IQ combined with IVIM-DWI provides valuable information for the diagnosis of osteoporosis and offers evidence for clinical decisions. The superior diagnostic performance of IVIM-DWI, particularly the D value, suggests its potential as a more sensitive and accurate method for diagnosing osteoporosis compared to IDEAL-IQ. These findings underscore the importance of integrating advanced imaging techniques into clinical practice for improved osteoporosis management and highlight the need for further research to explore the full clinical implications of these imaging modalities.

Estimation of intravoxel incoherent motion (IVIM) parameters in vertebral bone marrow: a comparative study of five algorithms

OBJECTIVES

To access the performances of different algorithms for quantification of Intravoxel incoherent motion (IVIM) parameters D, f, [Formula: see text] in Vertebral Bone Marrow (VBM).

MATERIALS AND METHODS

Five algorithms were studied: four deterministic algorithms (the One-Step and three segmented methods: Two-Step, Three-Step, and Fixed-[Formula: see text] algorithm) based on the least-squares (LSQ) method and a Bayesian probabilistic algorithm. Numerical simulations and quantification of IVIM parameters D, f, [Formula: see text] in vivo in vertebral bone marrow, were done on six healthy volunteers. The One-way repeated-measures analysis of variance (ANOVA) followed by Bonferroni's multiple comparison test (p value = 0.05) was applied.

RESULTS

In numerical simulations, the Bayesian algorithm provided the best estimation of D, f, [Formula: see text] compared to the deterministic algorithms. In vivo VBM-IVIM, the values of D and f estimated by the Bayesian algorithm were close to those of the One-Step method, in contrast to the three segmented methods.

DISCUSSION

The comparison of the five algorithms indicates that the Bayesian algorithm provides the best estimation of VBM-IVIM parameters, in both numerical simulations and in vivo data.

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.

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.

Radiomics analysis based on multiple parameters MR imaging in the spine: Predicting treatment response of osteolytic bone metastases to chemotherapy in breast cancer patients

PURPOSE

To assess the value of radiomics, apparent diffusion coefficient (ADC), intravoxel incoherent motion (IVIM) and stretched-exponential (SE) MR imaging in prediction of therapeutic response in patients with spinal metastases before chemotherapy.

METHODS

Thirty-six patients with 190 osteolytic metastatic lesions from breast cancer were prospectively enrolled and underwent MR imaging before and after 6 months' treatment on a 1.5 T MRI. According to MDA criteria, 68 lesions were categorized as progressive disease (PD) and 122 lesions were categorized as stable or improvement (non-PD). The regions of interest (ROIs) were manually drawn on DWI, T1WI, T2WI and FS-T2WI by two radiologists with ITK-SNAP. The ADC_all (multiple b-values method), IVIM parameters (D, D* and f) and SE parameters (DDC and α) were generated. The radiomics features were selected from the ROIs.

RESULTS

The mean values of ADC, DDC, and D before treatment were significantly higher in non-PD group than those in PD group (P = 0.001). The radiomics based on ADC_all had the highest AUC value (0.852), followed by that of the T2WI (0.829) and FS-T2WI (0.798). The radiomics model using ADC_all and FS-T2WI showed excellent efficiency in predicting treatment response with AUCs of 0.905 and 0.873 in training and validation cohorts. The radiomics model had better performance than that of ADC_all, D, and DDC for predicting treatment response of bone metastases.

CONCLUSION

Radiomics model based on ADC_all and FS-T2WI could predict the treatment response and contribute to assisting clinicians in accurately choosing appropriated management.

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.

Differentiation of Diffuse Infiltration Pattern in Multiple Myeloma From Hyperplastic Hematopoietic Bone Marrow: Qualitative and Quantitative Analysis Using Whole-Body MRI

BACKGROUND

The visual assessment used for diffuse infiltration of multiple myeloma (MM) is inadequate. It can be difficult to differentiate MM from hyperplastic hematopoietic bone marrow (HHBM) because the MRI signal characteristics overlap.

PURPOSE

To analyze the bone marrow diffuse signal changes on whole-body MRI caused by MM and HHBM.

STUDY TYPE

Retrospective.

SUBJECTS

Thirty Four patients with MM (21 men and 13 women), 22 patients with HHBM (9 men and 13 women), and 15 healthy controls (9 men and 6 women).

FIELD STRENGTH/SEQUENCE

A 3.0 T MRI; diffusion-weighted whole-body imaging with background body signal suppression (DWIBS), modified Dixon T1 fast field echo, and T2 STIR.

ASSESSMENT

Three radiologists analyzed the whole-body MRI alone and in combination with apparent diffusion coefficient (ADC) and fat fraction (FF) with qualitative and quantitative analysis. Normalized T1 and T2 signal intensities (nT1 and nT2) and signal-to-noise ratio (SNR) were obtained.

STATISTICAL TESTS

Kruskal-Wallis and chi-square tests.

RESULTS

The MM group had significantly higher ADC and significantly lower FF than HHBM and control groups. There was no significant difference in nT1, nT2 or SNR between MM and HHBM (P = 0.932, P = 0.097, and P = 0.110, respectively). Receiver operating characteristic (ROC) analysis using ADC and FF cut-off values of 0.47 × 10^-3  mm² /sec and 20.63%, respectively. The AUC was 0.866 for ADC and 0.886 for FF. The quantitative analysis yielded better specificity (observer 1: 81.8% vs. 27.3%; observer 2: 68.2% vs. 22.7%; and observer 3: 72.7% vs. 18.2%) and a higher diagnostic accuracy (observer 1: 82.1% vs. 51.8%; observer 2: 80.4% vs. 50.0%; observer 3: 76.8% vs. 44.6%) than the qualitative analysis.

DATA CONCLUSION

Whole-body MRI combined with DWIBS and mDIXON could be used to differentiate between MM and HHBM. Combining the quantitative ADC and FF with the whole-body MRI improved the specificity and accuracy in differentiating these conditions.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

Different Attenuation Models of Diffusion-Weighted MR Imaging for the Differentiation of Benign and Malignant Musculoskeletal Tumors

BACKGROUND

Several functional imaging techniques, including monoexponential diffusion-weighted imaging (m-DWI), intravoxel incoherent motion (IVIM), and diffusion kurtosis (DK) imaging, have been used in differentiating benign and malignant musculoskeletal tumors. Combining all three techniques in the same study population may improve differentiation.

PURPOSE

To compare the diagnostic performance of m-DWI, IVIM, and DK models and their combinations in differentiating benign and malignant musculoskeletal tumors.

STUDY TYPE

Prospective.

POPULATION

Fifty patients with benign and malignant musculoskeletal tumors divided into nonmyxoid and nonchondroid and myxoid and/or chondroid subgroups.

FIELD STRENGTH/SEQUENCE

A 1.5 T/m-DWI, IVIM, and DK single-shot spin-echo echo-planar sequences.

ASSESSMENT

Minimum and volumetric values of apparent diffusion coefficient (ADC), pure molecular diffusion (D_ivim ), pseudodiffusion (D*), perfusion fraction (f), diffusion coefficient for kurtosis model (D_K ), and Kurtosis (K) were compared between all benign and malignant tumors. Subgroup analysis was also performed for nonmyxoid and nonchondroid and myxoid and/or chondroid tumors.

STATISTICAL TESTS

Independent samples t-test, Mann-Whitney U test, intraclass correlation coefficient, ROC analysis, and logistic regression analysis. A P value < 0.05 was considered statistically significant.

RESULTS

ADC_min , D_ivim-min , D*_vol , D_K-min, K_vol, and K_min values showed statistically significant differences between all benign and malignant tumors and nonmyxoid and nonchondroid tumor subgroup. K_min showed the highest diagnostic performance in differentiating benign and malignant tumors with AUCs of 0.760 for "all tumors" and 0.825 for the nonmyxoid and nonchondroid tumor subgroup. No significant differences were detected in m-DWI-, IVIM-, and DK-derived parameters for differentiating benign and malignant myxoid and/or chondroid tumors. Only three of 63 combinations of prediction models demonstrated a higher diagnostic performance than K_min ; however, improvements were not significantly different.

DATA CONCLUSION

ADC_min , D_ivim-min , D*_vol , D_K-min , K_vol , and K_min values can be used to differentiate benign and malignant musculoskeletal tumors. Our findings suggest that the added value of multiparametric approach in such differentiation is not significant.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.

Pediatric skeletal diffusion-weighted magnetic resonance imaging, part 2: current and emerging applications

Diffusion-weighted imaging (DWI) complements the more established T1, fluid-sensitive and gadolinium-enhanced magnetic resonance pulse sequences used to assess several pediatric skeletal pathologies. There is optimism that the technique might not just be complementary but could serve as an alternative to gadolinium and radiopharmaceuticals for several indications. As a non-contrast, free-breathing and noninvasive technique, DWI is especially valuable in children and is readily incorporated into existing MRI protocols. The indications for skeletal DWI in children include distinguishing between benign and malignant skeletal processes, initial assessment and treatment response assessment for osseous sarcomas, and assessment of inflammatory arthropathies and femoral head ischemia, among others. A notable challenge of diffusion MRI is the dynamic nature of the growing pediatric skeleton. It is important to consider the child's age when placing DWI findings in context with potential marrow pathology. This review article summarizes the current and evolving applications of DWI for assessing the pediatric skeleton, rounding off the discussion with evolving directions for further research in this realm.

Pediatric skeletal diffusion-weighted magnetic resonance imaging: part 1 - technical considerations and optimization strategies

Diffusion-weighted MRI, or DWI, is a fast, quantitative technique that is easily integrated into a morphological MR acquisition. The ability of DWI to aid in detecting multifocal skeletal pathology and in characterizing tissue cellularity to a level beyond that possible with other techniques makes it a niche component of multiparametric MR imaging of the skeleton. Besides its role in disease detection and establishing cellularity and character of osseous lesions, DWI continues to be examined as a surrogate biomarker for therapeutic response of several childhood bone tumors. There is increasing interest in harnessing DWI as a potential substitute to alternative modes of imaging evaluation that involve radiation or administration of intravenous contrast agent or radiopharmaceuticals, for example in early detection and diagnosis of capital femoral epiphyseal ischemia in cases of Legg-Calvé-Perthes disease, or diagnosis and staging of lymphoma. The expected evolution of skeletal diffusivity characteristics with maturation and the unique disease processes that affect the pediatric skeleton necessitate a pediatric-specific discussion. In this article, the author examines the developmentally appropriate normal appearances, technique, artifacts and pitfalls of pediatric skeletal DWI.

Comparison of Field-of-view Optimized and Constrained Undistorted Single Shot With Conventional Intravoxel Incoherent Motion Diffusion-Weighted Imaging for Measurements of Diffusion and Perfusion in Vertebral Bone Marrow

BACKGROUND AND PURPOSE

A limited number of studies have used the intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) approach on bone marrow. The purpose of this study was to qualitatively and quantitatively compare the clinical value of IVIM based on field-of-view optimized and constrained undistorted single shot (FOCUS) with the standard single-shot echo-planar imaging (ss-EPI) in the vertebral bone marrow.

MATERIALS AND METHODS

Twenty healthy volunteers underwent ss-EPI and FOCUS IVIM-DWI of the lumbar spine. Intravoxel incoherent motion parameters (the apparent diffusion coefficient [ADC], true diffusion coefficient [D], pseudodiffusion coefficient [D*], and perfusion fraction [f]) were calculated.

RESULTS

The FOCUS IVIM protocol allowed for measurement of ADC, D, D*, and f in all volunteers: ADC, 0.28 ± 1.33 ×10-3 mm2/s; D = 0.25 ± 3.98 ×10-3 mm2/s, f = 0.36 ± 4.01; and D* = 102.16 ± 71.21 ×10-3 mm2/s. There were no significant differences between the values of ADC, D, and f obtained with ss-EPI and FOCUS. The D* was significantly different (P < 0.05) between ss-EPI and FOCUS IVIM. Image quality assessments showed that the image qualities of FOCUS were superior to ss-EPI (P < 0.001).

CONCLUSIONS

As a high-resolution IVIM-DWI technique, the FOCUS technique has potential clinical utility in evaluating the diffusion and perfusion in the vertebral bone marrow.

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.

Differentiating atypical hemangiomas and vertebral metastases: a field-of-view (FOV) and FOCUS intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) study

PURPOSE

Some atypical vertebral hemangiomas (VHs) may mimic metastases on routine MRI and can result in misdiagnosis and ultimately to additional imaging, biopsy and unnecessary costs. The purpose of this study is to assess the utility of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) on account of field-of-view optimized and constrained undistorted single shot (FOCUS) in distinguishing atypical VHs and vertebral metastases.

METHODS

A total of 25 patients with vertebral metastases and 25 patients with atypical VHs were confirmed by clinical follow-up or pathology. IVIM-DWI imaging was performed at different b values (0, 30, 50, 100, 150, 200, 400, 600, 800, 1000 mm²/s). IVIM parameters [the true diffusion coefficient (D), pseudodiffusion coefficient (D*), standard apparent diffusion coefficient (ADC), and perfusion fraction (f)] were calculated and compared between two groups by using Student's t test. A receiver operating characteristic analysis was performed.

RESULTS

Quantitative analysis of standard ADC and D parameters showed significantly lower values in vertebral metastases when compared to atypical hemangiomas [ADC value: (0.70 ± 0.12) × 10^-3 mm²/s vs (1.14 ± 0.28) × 10^-3 mm²/s; D value: (0.47 ± 0.07) × 10^-3 mm²/s vs (0.76 ± 0.14) × 10^-3 mm²/s, all P < 0.01]. The sensitivity and specificity of D value were 93.8% and 92.3%, respectively.

CONCLUSION

The standard ADC value and D value may be used as an indicator to distinguish vertebral metastases from atypical VHs. FOCUS IVIM-derived parameters provide potential value in the quantitatively differentiating vertebral metastases from vertebral atypical hemangiomas.

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.

Cardiac Intravoxel Incoherent Motion Diffusion-Weighted Magnetic Resonance Imaging With T1 Mapping to Assess Myocardial Perfusion and Fibrosis in Systemic Sclerosis: Association With Cardiac Events From a Prospective Cohort Study

OBJECTIVE

Myocardial involvement may occur during systemic sclerosis (SSc) and can lead to impaired myocardial contraction and/or arrhythmia. Cardiac magnetic resonance imaging (MRI) is used for noninvasive characterization of the myocardium. The aim of this study was to evaluate the utility of cardiac MRI with intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) and longitudinal relaxation time (T1) sequence mapping for assessment of myocardial microvascular and interstitium impairment in SSc.

METHODS

In this single-center prospective cohort study, 40 consecutive patients with SSc and 20 healthy controls were assessed by cardiac MRI with IVIM DWI and T1 mapping sequences on a 3T scanning system. Images were analyzed independently by 2 assessors, and Bland-Altman plots were used to assess interreader concordance and reproducibility. Characteristics of the patients were compared according to quartiles of T1 and perfusion fraction (f-coefficient) values, using exact Cochran-Ermitage trend tests for qualitative variables and analysis of variance for quantitative variables. Kaplan-Meier cardiac events-free survival curves were plotted and compared with a log-rank test for trend.

RESULTS

T1 values were higher in SSc patients than in healthy controls, and were higher in the diffuse cutaneous SSc (dcSSc) subset (P = 0.02). Higher T1 values were associated with the immunologic pattern seen in patients with the dcSSc form (P = 0.0001), a higher modified Rodnan skin thickness score (MRSS) (P = 0.003), and a higher frequency of interstitial lung disease (P = 0.03). Moreover, higher T1 values were correlated with higher MRSS scores (r = +0.32, P = 0.04) and reduced forced vital capacity (r = -0.34, P = 0.048), and tended to be correlated with reduced total lung capacity (r = -0.30, P = 0.07). Lower f-coefficient values, as a measure of decreased tissue perfusion, were associated with less frequent use of vasodilators (P = 0.02 for angiotensin-converting enzyme inhibitors and P = 0.06 for calcium-channel blockers) and more frequent use of glucocorticoids (P = 0.02). The f-coefficients were inversely correlated with the T1 values (r = -0.31, P = 0.02). Furthermore, higher T1 values were associated with higher incidence of cardiac events (log-rank test for trend P = 0.03).

CONCLUSION

Increased T1 values, potentially suggesting microscopic fibrosis, were observed more frequently in patients with dcSSc, and higher T1 values were associated with interstitial lung disease and more frequent cardiac events during follow-up. The results of this study show that cardiac MRI with T1 mapping sequences and IVIM DWI may be useful in assessing myocardial involvement in patients with SSc.

Diffusion MRI for Assessment of Bone Quality; A Review of Findings in Healthy Aging and Osteoporosis

Diffusion MRI (dMRI) is a growing imaging technique with the potential to provide biomarkers of tissue variation, such as cellular density, tissue anisotropy, and microvascular perfusion. However, the role of dMRI in characterizing different aspects of bone quality, especially in aging and osteoporosis, has not yet been fully established, particularly in clinical applications. The reason lies in the complications accompanied with implementation of dMRI in assessment of human bone structure, in terms of acquisition and quantification. Bone is a composite tissue comprising different elements, each contributing to the overall quality and functional competence of bone. As diffusion is a critical biophysical process in biological tissues, early changes of tissue microstructure and function can affect diffusive properties of the tissue. While there are multiple MRI methods to detect variations of individual properties of bone quality due to aging and osteoporosis, dMRI has potential to serve as a superior method for characterizing different aspects of bone quality within the same framework but with higher sensitivity to early alterations. This is mainly because several properties of the tissue including directionality and anisotropy of trabecular bone and cell density can be collected using only dMRI. In this review article, we first describe components of human bone that can be potentially detected by their diffusivity properties and contribute to variations in bone quality during aging and osteoporosis. Then we discuss considerations and challenges of dMRI in bone imaging, current status, and suggestions for development of dMRI in research studies and clinics to segregate different contributing components of bone quality in an integrated acquisition. Level of Evidence: 5 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020;51:975-992.

Correlation of histological marrow characteristics and intravoxel incoherent motion-derived parameters in benign and malignant hematological disorders

PURPOSE

To investigate the relationship between intravoxel incoherent motion (IVIM) parameters and histological parameters of vascularity and cellularity in marrow of hyperplasia disease and compare the difference between benign and malignant marrow disorders.

METHODS

From August 2016 to March 2017, 43 newly diagnosed patients were recruited, which included 15 anemia patients (benign hemopathy) and 28 patients with acute leukemia (AL) (malignant hemopathy). All patients underwent IVIM in the lumbar marrow and the D, D*, f values were measured. The microvessel density (MVD) and cellularity of marrow were calculated from the sample of iliac crest biopsy. Pearson correlation analysis was used to study the relationship between IVIM-derived and histology-derived parameters. We performed unpaired t test to analyze the differences of all parameters between AL and anemia.

RESULT

The MVD was positively correlated with f in patients with AL, anemia and both of them (r = 0.692, P < 0.001; r = 0.595, P = 0.019; r = 0.673, P < 0.001, respectively). But there was no correlation between D* and MVD in three groups. D was not related to bone marrow cellularity (BMC) in all groups. In addition, the f and MVD were higher in AL than anemia (t = 3.546, P = 0.001; t = 6.695, P < 0.001, respectively). The BMC was significantly higher in AL than in anemia (t = 3.330, P = 0.004), but D and D* value had no significant difference between the two groups.

CONCLUSION

The blood volume fraction f was positively correlated with the histological features of marrow in hematological disorders, while f can show the difference of vascularity between benign and malignant marrow disease.

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.

Intravoxel incoherent motion diffusion MR and diffusion kurtosis imaging for discriminating atypical bone metastasis from benign bone lesion

Objectives:

To investigate the feasibility of intravoxel incoherent motion (IVIM) diffusion MR and diffusion kurtosis imaging (DKI) in discriminating atypical bone metastasis from benign bone lesion in patients with tumors.

Methods:

Patients with bone lesions in lower extremity suspected of metastases were enrolled in this prospective study. IVIM diffusion MR and DKI were performed before biopsy. Apparent diffusion coefficient (ADC), true diffusion (D), perfusion fraction (f) and perfusion-related pseudodiffusion (D*) were generated with IVIM, while mean kurtosis (MK) and mean diffusion (MD) generated with DKI. Two radiologists blinded to pathology results separately measured these parameters for each lesion through drawing region of interest. Intraclass correlation coefficient was used to determine the inter-reader viability in measurement. The patients with pathology-confirmed metastasis or benign lesion were analyzed. The Mann–Whitney test was used to compare IVIM and DKI parameters between metastasis group and benign lesion group. Receiver operating characteristic curves were constructed to evaluate the ability of discrimination.

Results:

Bone lesions from 28 patients (metastasis, n = 15; benign lesion, n = 13; mean age = 55 years; age range, 34~77) were analyzed with IVIM and DKI. Intraclass correlation coefficient was greater than 0.8 for all parameters. ADC, D and MD were significantly lower in metastases versus benign lesions (p<0.05). MK and f value were significantly higher in metastases versus benign lesions (p<0.05). D* was not significantly different between the two groups (p>0.05). Areas under curve for ADC, D, f, MK and MD were 0.935, 0.939, 0.891, 0.840 and 0.844 respectively.

Conclusions:

IVIM and DKI derived parameters distinguish between atypical bone metastasis and benign bone lesion in selected patients with tumors.

Advances in knowledge:

Bone metastasis and benign bone lesion differ in water molecular diffusion.

Intravoxel incoherent motion derived true diffusion distinguishes between atypical bone metastasis and benign lesion.

MR Imaging of Pediatric Musculoskeletal Tumors:: Recent Advances and Clinical Applications

Pediatric musculoskeletal tumors comprise approximately 10% of childhood neoplasms, and MR imaging has been used as the imaging evaluation standard for these tumors. The role of MR imaging in these cases includes identification of tumor origin, tissue characterization, and definition of tumor extent and relationship to adjacent structures as well as therapeutic response in posttreatment surveillance. Technical advances have enabled quantitative evaluation of biochemical changes in tumors. This article reviews recent updates to MR imaging of pediatric musculoskeletal tumors, focusing on advanced MR imaging techniques and providing information on the relevant physics of these techniques, clinical applications, and pitfalls.

MRI biomarkers in osseous tumors

Although radiography continues to play a critical role in osseous tumor assessment, there have been remarkable advances in cross-sectional imaging. MRI has taken a lead in this assessment due to high tissue contrast and spatial resolution, which are well suited for bone lesion assessment. More recently, although somewhat lagging other organ systems, quantitative parameters have shown promising potential as biomarkers for osseous tumors. Among these sequences are chemical shift imaging (CSI), apparent diffusion coefficient (ADC), and intravoxel incoherent motion (IVIM) from diffusion-weighted imaging (DWI), quantitative dynamic contrast enhanced (DCE)-MRI, and magnetic resonance spectroscopy (MRS). In this article, we review the background and recent roles of these quantitative MRI biomarkers for osseous tumors. Level of Evidence: 3 Technical Efficacy Stage: 3 J. MAGN. RESON. IMAGING 2019. J. Magn. Reson. Imaging 2019;50:702-718.

Intravoxel incoherent motion and diffusion kurtosis imaging for discriminating soft tissue sarcoma from vascular anomalies

To investigate the feasibility of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) and diffusion kurtosis imaging (DKI) in discriminating soft tissue sarcoma from vascular anomalies.Twenty-two patients with lower extremity soft tissue sarcoma and 15 patients with lower extremity vascular anomalies underwent IVIM-DWI and DKI. IVIM model generated true diffusion (D), perfusion fraction (f), and pseudo-diffusion coefficient (D). DKI model generated mean kurtosis (MK) and mean diffusion (MD). These parameters were measured by 2 radiologists separately through drawing region of interest. Intraclass correlation coefficient (ICC) was calculated to evaluate the inter-reader viability in measurement. The Mann-Whitney test was used to compare the parameters between vascular anomalies and soft tissue sarcoma. Receiver operating characteristic curves were constructed for assessing diagnostic accuracies.ICC was more than 0.8 for apparent diffusion coefficient (ADC), D, D, f, MK, and MD. Mean ADC, D, and MD were significantly lower in soft tissue sarcoma versus vascular anomalies (P < .05). Mean D and f were not significantly different (P > .05). Soft tissue sarcoma had significantly higher MK than vascular anomalies (P < .05). Areas under curve for ADC, D, MK, and MD were 0.876, 0.885, 0.894, and 0.812, respectively.IVIM and DKI are feasible in discriminating soft tissue sarcoma from vascular anomalies.

Cerebral Blood Flow and Marrow Diffusion Alterations in Children with Sickle Cell Anemia after Bone Marrow Transplantation and Transfusion

BACKGROUND AND PURPOSE

Hematopoietic marrow hyperplasia and hyperperfusion are compensatory mechanisms in sickle cell anemia. We have observed marrow diffusion and arterial spin-labeling perfusion changes in sickle cell anemia following bone marrow transplantation. We aimed to compare arterial spin-labeling perfusion and marrow diffusion/ADC values in patients with sickle cell anemia before and after bone marrow transplantation or transfusion.

MATERIALS AND METHODS

We reviewed brain MRIs from patients with sickle cell anemia obtained during 6 consecutive years at a children's hospital. Quantitative marrow diffusion values were procured from the occipital and sphenoid bones. Pseudocontinuous arterial spin-labeling perfusion values (milliliters/100 g of tissue/min) of MCA, anterior cerebral artery, and posterior cerebral artery territories were determined. Territorial CBF, whole-brain average CBF, and marrow ADC values were compared for changes before and after either bone marrow transplantation or transfusion. Bone marrow transplantation and transfusion groups were compared. Two-tailed paired and unpaired Student t tests were used; P < .05 was considered significant.

RESULTS

Fifty-three examinations from 17 patients with bone marrow transplantation and 29 examinations from 9 patients with transfusion were included. ADC values significantly increased in the sphenoid and occipital marrow following bone marrow transplantation in contrast to patients with transfusion (P > .83). Whole-brain mean CBF significantly decreased following bone marrow transplantation (77.39 ± 13.78 to 60.39 ± 13.62 ml/100 g tissue/min; P < .001), without significant change thereafter. CBF did not significantly change following the first (81.11 ± 12.23 to 80.25 ± 8.27 ml/100 g tissue/min; P = .47) or subsequent transfusions. There was no significant difference in mean CBF between groups before intervention (P = .22).

CONCLUSIONS

Improved CBF and marrow diffusion eventuate following bone marrow transplantation in children with sickle cell anemia in contrast to transfusion therapy.