Objective To test the hypothesis that apparent diffusion coefficient (ADC) in vertebral bone marrow of benign and malignant fractures is related to the volume of the interstitial space, determined with dynamic contrast-enhanced (DCE) magnetic resonance imaging.Methods Patients with acute benign (n = 24) and malignant (n = 19) vertebral body fractures were examined at 1.5 T. A diffusion-weighted single-shot turbo-spin-echo sequence (b = 100 to 600 s/mm(2)) and DCE turbo-FLASH sequence were evaluated. Regions of interest were manually selected for each fracture. Apparent diffusion coefficient was determined with a monoexponential decay model. The DCE magnetic resonance imaging concentration-time curves were analyzed using a 2-compartment tracer-kinetic model.Results Apparent diffusion coefficient showed a significant positive correlation with interstitial volume in the whole study population (Pearson r = 0.66, P < 0.001), as well as in the malignant (Pearson r = 0.64, P = 0.004) and benign (Pearson r = 0.52, P = 0.01) subgroup. A significant correlation between ADC and the permeability-surface area product could be observed when analyzing the whole study population (Spearman r(s) = 0.40, P = 0.008), but not when separately examining the subgroups. Plasma flow showed a significant correlation with ADC in benign fractures (Pearson r = 0.23, P = 0.03). Plasma volume did not show significant correlations with ADC.Conclusions The results support the hypothesis that the ADC of a lesion is inversely correlated to its cellularity. This explains previous observations that ADC is reduced in more malignant lesions.

OBJECTIVE The purpose of our study was to determine the optimum combination of b values for calculating the apparent diffusion coefficient (ADC) using a diffusion-weighted (DW) single-shot turbo spin-echo (TSE) sequence in the differentiation between acute benign and malignant vertebral body fractures. SUBJECTS AND METHODS Twenty-six patients with osteoporotic (mean age, 69 years; range, 31.5-86.2 years) and 20 patients with malignant vertebral fractures (mean age, 63.4 years; range, 24.7-86.4 years) were studied. T1-weighted, STIR, and T2-weighted sequences were acquired at 1.5 T. A DW single-shot TSE sequence at different b values (100, 250, 400, and 600 s/mm(2)) was applied. On the DW images for each evaluated fracture, an ROI was manually adapted to the area of hyperintense signal intensity on STIR-hypointense signal on T1-weighted images. For each ROI, nine different combinations of two, three, and four b values were used to calculate the ADC using a least-squares algorithm. The Student t test and Mann-Whitney U test were used to determine significant differences between benign and malignant fractures. An ROC analysis and the Youden index were used to determine cutoff values for assessment of the highest sensitivity and specificity for the different ADC values. The positive (PPV) and negative predictive values (NPV) were also determined. RESULTS All calculated ADCs (except the combination of b = 400 s/mm(2) and b = 600 s/mm(2)) showed statistically significant differences between benign and malignant vertebral body fractures, with benign fractures having higher ADCs than malignant ones. The use of higher b values resulted in lower ADCs than those calculated with low b values. The highest AUC (0.85) showed the ADCs calculated with b = 100 and 400 s/mm(2), and the second highest AUC (0.829) showed the ADCs calculated with b = 100, 250, and 400 s/mm(2). The Youden index with equal weight given to sensitivity and specificity suggests use of an ADC calculated with b = 100, 250, and 400 s/mm(2) (cutoff ADC, < 1.7 × 10(-3) mm(2)/s) to best diagnose malignancy (sensitivity, 85%; specificity, 84.6%; PPV, 81.0%; NPV, 88.0%). CONCLUSION ADCs calculated with a combination of low to intermediate b values (b = 100, 250, and 400 s/mm(2)) provide the best diagnostic performance of a DW single-shot TSE sequence to differentiate acute benign and malignant vertebral body fractures.

OBJECTIVE The objective of our study was to evaluate quantitative dynamic contrast-enhanced MRI (DCE-MRI) based on tracer kinetic modeling of perfusion in the differentiation of benign from malignant vertebral fractures. SUBJECTS AND METHODS Patients with 26 osteoporotic vertebral fractures (18 women, eight men; mean age, 69 years) and patients with 20 malignant vertebral fractures (nine women, 11 men; mean age, 63.4 years) underwent dynamic contrast-enhanced MRI. T1-weighted, STIR, and T2-weighted sequences were acquired at 1.5 T. Dynamic contrast-enhanced image sets were acquired with a 2D saturation-recovery spoiled gradient-echo sequence. Regions of interest in parameter maps of mean transit time (MTT) and plasma flow in the fractured vertebral bodies were analyzed with a two-compartment tracer kinetic model. Plasma flow, plasma volume (PV), extraction flow, and interstitial volume were calculated. The forward volume transfer constant (K(trans)) and the extracellular volume (ECV) were derived. A two-tailed Fisher exact test, Mann-Whitney U test, and receiver operating characteristic analysis were performed. RESULTS Forty-four vertebral fractures in 44 patients could be evaluated. In spots of increased plasma flow, interstitial volume (p = 0.0003), ECV (p = 0.002), and extraction flow (p = 0.03) for osteoporotic and malignant vertebral fractures were significantly different. The mean interstitial volume was 28.62 mL/100 mL for osteoporotic fractures and 11.73 mL/100 mL for malignant fractures, and the area under the curve (AUC) was 0.819 for a cutoff of 11.72 mL/100 mL or less indicating malignancy (sensitivity, 63.2%; specificity, 96.0%). The mean ECV was 52.68 mL/100 mL for osteoporotic fractures and 36.71 mL/100 mL for malignant fractures, and the AUC was 0.802 for a cutoff of 35.83 mL/100 mL or less indicating malignancy (sensitivity, 63.2%; specificity, 92.0%). The mean extraction flow was 15.19 mL/100 mL/min for osteoporotic fractures and 23.67 mL/100 mL/min for malignant fractures, and the AUC was 0.693 for a cutoff of 6.52 mL/100 mL/min or less indicating malignancy (sensitivity, 57.9%; specificity, 92.0%). K(trans), plasma flow, and PV in the spots of increased plasma flow and all quantitative perfusion parameters in the regions of increased MTT did not show any significant differences between benign and malignant fractures. CONCLUSION In spots of high plasma flow, which can be determined with a deconvolution analysis, the quantitative perfusion parameters of interstitial volume, ECV, and extraction flow are significantly different between acute osteoporotic and malignant vertebral fractures and can aid in the distinction between the two entities.

OBJECTIVE. The objective of our study was to compare the diagnostic value of qualitative diffusion-weighted imaging (DWI), quantitative DWI, and chemical-shift imaging in a single prospective cohort of patients with acute osteoporotic and malignant vertebral fractures.SUBJECTS AND METHODS. The study group was composed of patients with 26 osteoporotic vertebral fractures (18 women, eight men; mean age, 69 years; age range, 31 years 6 months to 86 years 2 months) and 20 malignant vertebral fractures (nine women, 11 men; mean age, 63.4 years; age range, 24 years 8 months to 86 years 4 months). T1-weighted, STIR, and T2-weighted sequences were acquired at 1.5 T. A DW reverse fast imaging with steady-state free precession (PSIF) sequence at different delta values was evaluated qualitatively. A DW echo-planar imaging (EPI) sequence and a DW single-shot turbo spin-echo (TSE) sequence at different b values were evaluated qualitatively and quantitatively using the apparent diffusion coefficient. Opposed-phase sequences were used to assess signal intensity qualitatively. The signal loss between in-and opposed-phase images was determined quantitatively. Two-tailed Fisher exact test, Mann-Whitney test, and receiver operating characteristic analysis were performed. Sensitivities, specificities, and accuracies were determined.RESULTS. Qualitative DW-PSIF imaging (delta = 3 ms) showed the best performance for distinguishing between benign and malignant fractures (sensitivity, 100%; specificity, 88.5%; accuracy, 93.5%). Qualitative DW-EPI (b = 50 s/mm(2) [p = 1.00]; b = 250 s/mm(2) [p = 0.50]) and DW single-shot TSE imaging (b = 100 s/mm(2) [p = 1.00]; b = 250 s/mm(2) [p = 0.18]; b = 400 s/mm(2) [p = 0.18]; b = 600 s/mm(2) [p = 0.39]) did not indicate significant differences between benign and malignant fractures. DW-EPI using a b value of 500 s/mm(2) (p = 0.01) indicated significant differences between benign and malignant vertebral fractures. Quantitative DW-EPI (p = 0.09) and qualitative opposed-phase imaging (p = 0.06) did not exhibit significant differences, quantitative DW single-shot TSE imaging (p = 0.002) and quantitative chemical-shift imaging (p = 0.01) showed significant differences between benign and malignant fractures.CONCLUSION. The DW-PSIF sequence (delta = 3 ms) had the highest accuracy in differentiating benign from malignant vertebral fractures. Quantitative chemical-shift imaging and quantitative DW single-shot TSE imaging had a lower accuracy than DW-PSIF imaging because of a large overlap. Qualitative assessment of opposed-phase, DW-EPI, and DW single-shot TSE sequences and quantitative assessment of the DW-EPI sequence were not suitable for distinguishing between benign and malignant vertebral fractures.

Objectives: The aim of this study was to assess and delineate chronic myocardial infarction (CMI) using precontrast and postcontrast T1 mapping techniques including quantification of extracellular volume fractions (ECVs).Materials and Methods: A total of 26 patients with CMI were examined at 1.5 T applying a modified Look-Locker Inversion Recovery sequence before and 10 minutes after contrast at 3 short-axis slice positions. An inversion recovery gradient recalled echo sequence (standard of reference) was used for imaging late gadolinium enhancement. Precontrast and postcontrast T1 maps were calculated, and CMI was defined as areas with T1 values more than 3 SDs different compared with normal myocardium (MYO). T1 values of CMI, MYO, and blood pool were measured, and ECVs of CMI and MYO were calculated. Two-tailed Student t test was used for statistical analysis of T1 values and ECVs. Sensitivities and specificities for detection of CMI on precontrast and postcontrast T1 maps were calculated. Receiver operating characteristic (ROC) analysis was performed for postcontrast T1 values and ECV for discrimination of CMI.Results: The comparison of T1 values of CMI and MYO revealed significant differences in precontrast and postcontrast scans (1159 +/- 64 vs 1001 +/- 47 milliseconds, P < 0.001, and 238 +/- 74 vs 379 +/- 59 milliseconds, P < 0.001). Sensitivities and specificities for detection of CMI on T1 mapping were 41.7% and 100% in precontrast Look-Locker Inversion Recovery scans and 95.8% and 99.3% in postcontrast images, respectively. Average ECV for MYO and CMI were 28% +/- 5% and 53% +/- 10% (P < 0.001). ROC analysis revealed nonsignificantly different areas under the curve of 0.937 and 0.997 for T1 values and ECV, respectively (P = 0.137). Sensitivities and specificities were 92.3% and 92.3% for detecting CMI by postcontrast T1 values and 95.5% and 100% for ECV, with cutoff values being 305 milliseconds or less and greater than 42%. Combined criteria did not result in any further improvement of sensitivity for CMI detection.Conclusions: Postcontrast T1 values and ECV of chronically infarcted MYO are significantly different compared with respective values of normal MYO. Both parameters allow for accurate detection of CMI with ECV showing marginally higher sensitivity and specificity. Precontrast T1 values lack accuracy in delineation of CMI.

Purpose: Comparison of 3 optimized pulse sequences for thoracoabdominal contrast-enhanced magnetic-resonance angiography by signal-to-noise measurements and time-dependent T1 mapping in the steady state after injection of 0.03 mmol/kg BW gadofosveset.Materials and Methods: After institutional review board approval, 15 healthy volunteers (19-46 years, mean age: 31.5 years) were included in this prospective, intraindividual comparison study. All examinations were performed at 1.5 T. Three pulse sequences: volume interpolated breath-hold examination (VIBE) sequences as VIBE(SEMI) (echo time [TE]: 1.64 milliseconds, repetition time [TR]: 3.77 milliseconds, FA: 15 degrees, voxel size: 1.2 x 1.2 x 1.2 mm(3)) with short TR, VIBE(OPT) (TE: 2.2 milliseconds, TR: 5.2, FA: 15 degree, voxel size: 1.2 x 1.2 x 1.2 mm(3)) with long TR, and a typical 3-dimensional fast low angle shot (FLASH) sequence (TE: 1.39 milliseconds, TR: 3.77 milliseconds, FA: 25 degree, voxel size: 1.0 x 0.8 x 1.0 mm(3)) were repeated 10, 20, 30, and 40 minutes after the injection of 0.03 mmol/kg BW gadofosveset (mean dose: 9.7 mL). Mean signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were computed for the aorta and the inferior vena cava (IVC). Three-dimensional gradient echo sequences with variable flip angles were performed for T1 mapping 0 to 50 minutes postinjection (p.i.). Additional phantom measurements were performed to compare the sequences.Results: Significantly higher SNR values of the FLASH were found at every point compared with VIBE(OPT) (P = 0.002-P = 0.004), but only 10, respectively, 20 minutes p.i. to VIBE(SEMI). No significant differences of SNR were obtained between VIBE(SEMI) and VIBE(OPT). In the aorta, the maximal percentage gain of SNR was 29.2% for 3D-FLASH compared with VIBE(SEMI). Similar, but mostly not significant, results were obtained regarding the SNR in the IVC with the 3D-FLASH sequence yielding higher SNR versus both comparators (P = 0.007-P = 0.466). Except 10 minutes p.i., CNR analysis yielded higher values for the VIBE(SEMI) versus both comparators in the aorta as well as in the IVC. No statistical significant difference was found for the VIBE(SEMI) versus the 3D-FLASH sequence in all comparisons. Regarding the phantom measurements, statistically significant higher SNR was found for the VIBE(SEMI) versus the 3D-FLASH. The T1 time in the aorta decreased p.i. from 1227 +/- 383 milliseconds to 141 +/- 27 milliseconds and showed over the time a slow reincrease to 175 +/- 29 milliseconds at 50 minutes p.i.Conclusion: Ten to 30 minutes after injection of gadofosveset, a relatively constant longitudinal relaxation is given. In this steady state, no additional improvements were obtained by theoretically optimized sequence parameters in the VIBE(OPT) with a longer TR.

Objectives: Diffusion-weighted steady-state free precession (DW-SSFP) sequences have shown great potential for the differential diagnosis of benign osteoporotic and malignant neoplastic vertebral compression fractures, which appear hypo- to isointense or hyperintense in DW-SSFP magnetic resonance imaging, respectively. In contrast to other diffusion weighting sequences, the DW-SSFP signal depends not only on the apparent diffusion coefficient (ADC), but also on the tissue relaxation times and sequence parameters. The purpose of the present study was to provide a detailed analysis of the DW-SSFP signal in benign and malignant vertebral lesions (VLs) and in vertebral bone marrow (VBM) to understand the observed signal alterations and their dependence on tissue and sequence parameters.Materials and Methods: Magnetic resonance imaging was performed in 40 patients with benign (n = 20) or malignant (n = 20) VLs to determine the fat fraction and tissue parameters (ADC, T(1), T(2), T(2)*) for both the water and fat signal. With these values, the DW-SSFP signal was simulated and compared with the measured signals for different diffusion gradients by determining the signal intensity ratio between the SSFP signals of the lesions and of normal-appearing VBM for both malignant and benign VLs.Results: The simulated DW-SSFP contrast agreed well with the measured contrast and provided a very good differentiation between benign osteoporotic and malignant VLs. ADCs were significantly different in both lesion types (malignant 1.36 vs. osteoporotic 1.77 x 10(-3) mm(2)/s); however, the observed contrast differences were caused predominantly by an opposed-phase readout in combination with significantly different T(2)* values (malignant 22 vs. osteoporotic 14 ms) and fat fractions (malignant 3.9% vs. osteoporotic 12%) in the lesions as well as significantly different fat fractions in normal-appearing VBM (malignant 42% vs. osteoporotic 52%) of both patient groups.Conclusions: Although the ADCs of the evaluated malignant and benign VLs showed highly significant differences, the influence of diffusion on the DW-SSFP signal contrast is relatively low compared with other tissue parameters due to the very complex signal mechanism of the SSFP sequence. Thus, the observed DW-SSFP signal contrast of different VLs (hypo-/isointense vs. hyperintense signal) is rather fat- and T(2)*-weighted than diffusion-weighted. The intermediate diffusion weighting of the applied SSFP sequence, however, helps to shift the different contrasts into a signal range that is easily visually accessible.

PURPOSE:To evaluate the potential of quantitative dynamic contrast-enhanced MRI (DCE-MRI) in vertebral bone marrow (vBM) of patients with acute osteoporotic vertebral compression fractures.MATERIALS AND METHODS:Twenty-six patients with acute osteoporotic fractures (16 female, 10 male, median age 72, range 48-89) and 10 subjects without known history of osteoporosis (6 female, 4 male, median 65, range 31-77) were examined 2D-DCE-MRI. Region of interest (ROI) data in fractured (n = 26) and normal-appearing vertebrae (n = 271) were analyzed with a two-compartment tracer-kinetic-model, providing estimates of at least three independent parameters: plasma flow (PF), plasma volume (PV), and extraction flow (EF). Parameters were correlated with dual x-ray absorptiometry (DXA) (n = 15) and quantitative computed tomography (QCT) densitometry (n = 10).RESULTS:Mean PF was significantly higher in fractures than in normal-appearing vertebrae (69.37 vs. 11.72 mL/100 mL/min). Similarly, mean PV and EF differed significantly. Mean PF was significantly decreased in normal-appearing vBM osteoporotic patients compared to the control group. Mean PF and PV were significantly decreased in lumbar compared to thoracic vertebrae. PV showed a significant correlation with QCT.CONCLUSION:Perfusion parameters were decreased significantly in normal-appearing vBM of patients. Furthermore, significant perfusion alterations were observed in acute osteoporotic vertebral fractures compared to normal-appearing vertebrae.

Objectives: To evaluate the potential and to analyze parameter correlations of combined quantitative diffusion-weighted MRI (DWI) and high-temporal-resolution dynamic contrast-enhanced MRI (DCE-MRI) in vertebral bone marrow (vBM) of patients with osteoporosis and acute vertebral compression fractures, providing additional information for a better understanding of the physiological background of parameter changes.Materials and methods: 20 patients with acute osteoporotic fractures were examined with DWI and DCE-MRI at 1.5 T. DCE-MRI was performed with a 2D saturation-recovery turbo-FLASH sequence, acquiring 300 dynamics with a temporal resolution of 1 s. For DWI measurements, a DW HASTE sequence with b-values from 100 to 600s/mm(2) was applied. In each patient, ROIs were drawn manually in the fractures and in normal appearing vertebrae. For DCE-MRI, the concentration-time curves of these ROIs were analyzed using a two-compartment tracer-kinetic model in the lesions, providing separate estimates of perfusion and permeability, and a one-compartment model in normal vBM, providing only a mixed representation of perfusion and permeability in terms of a mixed flow parameter K-trans and the extracellular volume (ECV). In the case of DWI, attenuation curves were fitted to a monoexponential decay model to determine the apparent diffusion coefficient (ADC).Results: Mean perfusion parameters and ADCs were significantly (p < 0.001) different in the fractures compared to adjacent normal appearing vertebrae (K-trans: 7.81 mL/100 mL/min vs. 14.61 mL/100 mL/min, ECV: 52.84 mL/100mL vs. 4.61 mL/100 mL, ADC: 1.71 x 10(-3) mm(2)/s vs. 0.57 x 10(-3) mm(2)/s). ADCs showed a significant correlation with the ECV.Conclusion: The quantitative analysis of DWI and DCE-MRI could distinguish osteoporotic fractures from normal appearing vertebrae. A significant correlation found between ECV and ADCs might be able to explain the cause for the increased diffusivity in osteoporotic fractures. Since the other perfusion parameters do not correlate with the ADC, they provide additional pathophysiological information not accessible with DWI. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

At a given field strength tissues present with specific T 1values.Reference values for normal unenhanced myocardium have been established.We hypothesize, that infarcted myocardial tissue can be delineated from normal myocardium by means of T 1 -maps in unenhanced and contrast-enhanced scans.

To evaluate spin-lattice (T1) and spin-spin (T2) relaxation times as well as apparent diffusion coefficients (ADCs) of the fat and water components in the vertebral bone marrow (vBM) of patients with benign and malignant lesions.

In diffusion-weighted magnetic resonance imaging (DWI), the intensity of the acquired magnetic resonance signal depends on the self-diffusion of the excited spins, i.e., on the microscopic stochastic Brownian molecular motion. Since the extent and orientation of molecular motion is influenced by the microscopic structure and organization of biological tissues, DWI can depict various pathological changes of organs or tissues. While DWI of the brain can be considered an established technique since the mid-1990s, significantly fewer studies have been published about DWI in body imaging, mainly because of the relatively low robustness of conventional DWI methods in non-neurological applications. Consequently, the image quality in such applications was rather limited. This situation, however, improved considerably in recent years due to better hardware as well as new pulse sequences, and several new applications of DWI (e.g., in the abdominal organs, in musculoskeletal applications, or in whole-body protocols) have been described. Unfortunately, DWI of the body is complicated by frequently low signal-to-noise ratios due to shorter transversal (T2) relaxation times and by strong variations of susceptibility. The latter result in severe distortion artifacts when standard echo-planar DWI techniques are applied. Hence, several alternative (non-echo-planar) diffusion-weighting pulse sequence types were proposed and evaluated for DWI applications in the body. In this review article, first the basics of molecular diffusion and of diffusion-weighted MRI are introduced and then several specific MRI techniques, which have been used for DWI of the body, are described. Finally, protocol recommendations for different DWI applications in the body are provided.

Dynamic contrast-enhanced MRI data in vertebral bone marrow (vBM) are currently analyzed with descriptive indices. The purpose of this study was to develop and evaluate a quantitative approach, considering the tissue composition of vBM. Therefore, a measurement of the water fraction, f(wat), and the precontrast relaxation times, T(10 wat), T(10 fat), was added to the routine protocol. Signal analysis was generalized by allowing for an arbitrary fraction of fat. Plasma flow, plasma volume, extraction flow, and interstitial volume were determined from dynamic contrast-enhanced-MRI data. Simulations were used to determine the sensitivity to the precontrast values and to retrospectively verify the choice of the sequence parameters. Measurements were performed in healthy vertebral bodies (n = 30) and lesions of 15 patients with vertebral fractures. Extraction flow (milliliters per 100 mL/min) provided the strongest normal/abnormal separation: mean (standard deviation) was 0.3 (0.8) in healthy vBM and 6(4) in the fractures. Neglecting the fat component and the approximated signal analysis using relative signal enhancement produced significant differences. We conclude that correcting for the fat component in the signal and parametrization by tracer-kinetic analysis is necessary to avoid misinterpretation and/or systematic errors. The quantitative analysis is equally well suited as a descriptive parameter for the differentiation between normal and abnormal vertebral bone marrow.

In diffusion-weighted magnetic resonance imaging (DWI), the observed MRI signal intensity is attenuated by the self-diffusion of water molecules. DWI provides information about the microscopic structure and organization of a biological tissue, since the extent and orientation of molecular motion is influenced by these tissue properties. The most common method to measure perfusion in the body using MRI is T1-weighted dynamic contrast enhancement (DCE-MRI). The analysis of DCE-MRI data allows determining the perfusion and permeability of a biological tissue. DWI as well as DCE-MRI are established techniques in MRI of the brain, while significantly fewer studies have been published in body imaging. In recent years, both techniques have been applied successfully in healthy bone marrow as well as for the characterization of bone marrow alterations or lesions; e.g., DWI has been used in particular for the differentiation of benign and malignant vertebral compression fractures. In this review article, firstly a short introduction to diffusion-weighted and dynamic contrast-enhanced MRI is given. Non-quantitative and quantitative approaches for the analysis of DWI and semiquantitative and quantitative approaches for the analysis of DCE-MRI are introduced. Afterwards a detailed overview of the results of both techniques in healthy bone marrow and their applications for the diagnosis of various bone-marrow pathologies, like osteoporosis, bone tumors, and vertebral compression fractures are described.

In diffusion-weighted magnetic resonance imaging (DWI-MRI), the observed MRI signal intensity is attenuated by the self-diffusion of water molecules. DWI can provide information about the microscopic structure and organization of biological tissue and thus can depict various pathological changes of organs or tissues. DWI has been successfully used for the characterization of bone marrow alterations or lesions, and in particular for the differentiation of benign and malignant vertebral compression fractures. In this review article, the basics of DWI are introduced, and several pulse sequences that have been used for DWI of the bone marrow are described. Subsequently, an extensive overview about diffusion studies of the bone marrow and in particular of DWI of vertebral compression fractures is provided.