Dynamic contrast-enhanced magnetic resonance imaging can assess vascularity within fracture non-unions and predicts good outcome

Alteration in Microcirculation With Osteonecrosis of the Femoral Head: A Study of Dynamic Contrast-Enhanced MRI

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is commonly used in clinical practice to detect tumor blood supply, and it has recently been applied to assess skeletal vasculature. In this study, we retrospectively analyzed DCE-MRI data from 37 patients with osteonecrosis of the femoral head to evaluate alterations in microvascular circulation of the femoral head. Time-intensity curves (TICs) in the region of interest were classified into different lesion stages. In the greater trochanter area, extracellular space volume per unit volume of tissue was significantly higher in Association Research Circulation Osseous (ARCO) stage III than in ARCO stage II (P<.05 and power ≥ 0.8), while other parameters showed no statistical difference (P>.05 and/or power < 0.8). In the necrotic area, contrast enhancement ratio and maximum slope of increase were significantly lower in ARCO stage III than in ARCO stage II (P<.05 and power ≥ 0.8), while other parameters showed no statistical difference (P>.05 and/or power < 0.8). In the repair reaction area, all parameters were significantly higher in ARCO stage III than in ARCO stage II (P<.05 and power ≥ 0.8). TIC classification showed that the greater trochanter area mainly exhibited type C (plateau type), the necrotic area mainly exhibited type B (out-flow type), and the repair reaction area mainly exhibited type A (inflow type). We believe that the exchange capacity of the vessels has a much greater impact on femoral head necrosis than the number of vessels, while the generation of the repair area greatly affects the prognosis of femoral head necrosis. These findings suggest that DCE-MRI can provide a good assessment of osteonecrosis of the femoral head perfusion and can serve as a new reference for clinical treatment decisions. [Orthopedics. 2024;47(2):e73-e78.].

Principles and Evaluation of Bony Unions

Nonunion is a common and costly problem. Unfortunately, there is no widely agreed upon and standardized definition for nonunion. The evaluation of bony union should start with a thorough history and physical examination. The clinician should consider patient-dependent as well as patient-independent characteristics that may influence the rate of healing and evaluate the patient for physical examination findings suggestive of bony union and infection. Radiographs and clinical examination can help confirm a diagnosis of union. When the diagnosis is in doubt, however, advanced imaging modalities as well as laboratory studies can help a surgeon determine when further intervention is necessary.

The Many Faces of Marrow Necrosis

Depending on the age and location within the skeleton, bone marrow can be mostly fatty or hematopoietic, and both types can be affected by marrow necrosis. This review article highlights the magnetic resonance imaging findings of disorders in which marrow necrosis is the dominant feature.Fatty marrow necrosis is detected on T1-weighted images that show an early and specific finding: the reactive interface. Collapse is a frequent complication of epiphyseal necrosis and detected on fat-suppressed fluid-sensitive sequences or using conventional radiographs. Nonfatty marrow necrosis is less frequently diagnosed. It is poorly visible on T1-weighted images, and it is detected on fat-suppressed fluid-sensitive images or by the lack of enhancement after contrast injection.Pathologies historically "misnamed" as osteonecrosis but do not share the same histologic or imaging features of marrow necrosis are also highlighted.

Dynamic contrast-enhanced fluorescence imaging compared with MR imaging in evaluating bone perfusion during open orthopedic surgery

ICG-based dynamic contrast-enhanced fluorescence imaging (DCE-FI) and intraoperative DCE- magnetic resonance imaging (MRI) have been carried out nearly simultaneously in three lower extremity bone infection cases to investigate the relationship between these two imaging modalities for assessing bone blood perfusion during open orthopedic surgeries. Time-intensity curves in the corresponding regions of interest of two modalities were derived for comparison. The results demonstrated that ICG-based DCE-FI has higher sensitivity to perfusion changes while DCE-MRI provides superior and supplemental depth-related perfusion information. Research applying the depth-related perfusion information derived from MRI to improve the overall analytic modeling of intraoperative DCE-FI is ongoing.

Contrast-Enhanced Ultrasound: A Viable Diagnostic Tool in Predicting Treatment Failure after Non-union Revision Surgery for Upper- and Lower-Limb Non-unions

Non-unions remain a major complication in the treatment of long-bone fractures and affect quality of life considerably. Both early detection and treatment of non-unions are essential to secure subsequent fracture union. Sufficient vascularization plays a key role in the healing process. The aim of this prospective study was to quantify the microperfusion within non-unions by means of contrast-enhanced ultrasound (CEUS) as early as 12 wk after non-union surgery and to examine the prognostic capability of CEUS in predicting treatment failure. Among 112 patients who had undergone non-union surgery, consolidation within 36 mo was achieved in 89 patients ("responders"), whereas 23 patients showed persistent non-unions ("non-responders") and required further surgery. CEUS quantification parameters such as peak enhancement, wash-in area under the curve and wash-in perfusion index revealed significantly higher perfusion levels in "responders" compared with "non-responders" (p < 0.05). Receiver operator characteristic curve analysis revealed that persistent fracture non-unions could be predicted with a sensitivity/specificity of 88.7%/72.2% in lower-limb non-unions and a sensitivity/specificity of 66.7%/100.0% in upper-limb non-unions. CEUS is a suitable diagnostic tool in predicting treatment failure as early as 12 wk after non-union surgery and should be integrated into the clinical routine when deciding on revision surgery at an early stage.

Updates in postoperative imaging modalities following musculoskeletal surgery

Postoperative imaging following orthopaedic surgeries is essential in assessing complications post-surgery and also helps plan further treatment. Combining a high degree of clinical insight with appropriate imaging can guide the treating clinician to the correct diagnosis. Imaging is quite challenging because of surgery-related soft tissue changes, especially in the early postoperative period and the presence of metal implants resulting in image scatter and metal artifacts. Newer modalities and advances in imaging have helped overcome shortcomings and assess better, especially in procedures that involve implants. Collaborative decision-making involving radiologists and clinicians has shown to be beneficial and is the way forward. This narrative review discusses the utility of imaging in evaluating postoperative complications following musculoskeletal surgeries with specific relation to trauma, arthroplasty, and tumour by discussing commonly encountered clinical scenarios.

Monitoring of fracture healing. Update on current and future imaging modalities to predict union

Fracture nonunion causes considerable patient morbidity and an associated burden to society. Traditional reliance on radiographs to monitor union has limitations as bridging callus of long bone fractures can take three or more months to occur. Computed Tomographic (CT) scanning is becoming increasingly popular and can evaluate bridging callus in the late stages of healing to confirm union. The use of dynamic contrast enhanced Magnetic Resonance Imaging (MRI) and advances in nuclear imaging may yield benefits in the assessment of the infected nonunion. Emerging evidence supports the use of ultrasound to detect bridging callus prior to radiographic confirmation and it may be of use to predict patients at high risk of nonunion. This paper is part of a Supplement supported by The Osteosynthesis and Trauma Care Foundation (OTCF).

Posttraumatic Perfusion Analysis of Quadriceps, Patellar, and Achilles Tendon Regeneration With Dynamic Contrast-Enhanced Ultrasound and Dynamic Contrast-Enhanced Magnetic Resonance Imaging: Preliminary Results

OBJECTIVES

The healing process of tendons after surgical treatment of tendon ruptures mainly depends on the perfusion of the tendon and its surrounding tissue. Dynamic contrast-enhanced ultrasound (DCE-US) and dynamic contrast-enhanced MRI (DCE-MRI) can provide additional information about the local microperfusion. In this pilot study, the feasibility of these techniques to assess the vascularization during tendon regeneration was evaluated.

METHODS

Between 2013 and 2015, 23 patients with surgical treatment of traumatic rupture of quadriceps, patellar, and Achilles tendons were involved. All patients received clinical follow-up examinations at 6, 12, and at least 52 weeks postoperatively. Dynamic contrast-enhanced US and DCE-MRI examinations were performed 6 and 12 weeks postoperatively. Dynamic contrast-enhanced US perfusion was quantified by the parameters peak enhancement, wash-in area under the curve, rise time, and initial area under the curve. Correlations between these parameters were examined via the Spearman rank correlation. The clinical and functional outcomes were assessed via the Lysholm Knee Score and Knee and Osteoarthritis Outcome Score at 12 and 52 weeks postoperatively.

RESULTS

Fourteen patients with quadriceps (n = 8), patellar (n = 4) and Achilles (n = 2) tendon ruptures with complete follow-up were available. The microperfusion could be successful assessed. We could detect a strong correlation of DCE-US (peak enhancement) parameters with DCE-MRI (initial area under the curve) parameters after 6 and 12 weeks.

CONCLUSIONS

In this pilot study, DCE-US was able to visualize the microperfusion of healing tendons with a strong correlation with DCE-MRI. Our initial results are in favor of DCE-US as a potential quantitative imaging tool for evaluating the vascularization in tendon regeneration as a complementary method.

The AMANDUS Project PART II-Advanced Microperfusion Assessed Non-Union Diagnostics with Contrast-Enhanced Ultrasound (CEUS): A Reliable Diagnostic Tool for the Management and Pre-operative Detection of Infected Upper-Limb Non-unions

The management of upper-limb non-unions can be challenging, especially when infection is existent. Thus, pre-operative detection of infection plays a relevant role in non-union treatment. This study investigated in a large cohort the diagnostic potential of contrast-enhanced ultrasound (CEUS) as stand-alone method for differentiating between aseptic and infected upper-limb non-unions. Osseous perfusion of 50 upper-extremity non-unions (radius/ulna, n = 20; humerus, n = 22; clavicle, n = 8) was prospectively assessed with CEUS before revision surgery. The perfusion was quantified via time-intensity curves and peak enhancement (in arbitrary units). Significant perfusion differences between aseptic and infected non-unions could be detected (peak enhancement, p < 0.001). The sensitivity and specificity for the detection of infected upper-limb non-unions were 80% and 94.3% (cutoff peak enhancement: 130.8 arbitrary units). CEUS reliably differentiates between aseptic and infected upper-limb non-unions. Consequently, CEUS should be integrated into the daily diagnostic routine algorithm to plan non-union revision surgery more precisely as a single- or multi-step procedure.

Assessment of neovascularization during bone healing using contrast-enhanced ultrasonography in a canine tibial osteotomy model: a preliminary study

Blood perfusion of skeletal muscle and callus was evaluated using contrast-enhanced ultrasonography (CEUS) in a canine osteotomy model to determine the applicability of CEUS in the assessment of neovascularization during fracture healing and to compare the vascular signals on CEUS between external skeletal fixation and cast-applied dogs. In 6 Beagle dogs, a simple transverse osteotomy was performed at the left tibial shaft and external skeletal fixation (n = 3) or a cast (n = 3) was applied. Radiography, power Doppler ultrasonography (power Doppler), and CEUS were performed until complete union was achieved. On CEUS, vascular changes were quantitatively evaluated by measuring peak intensity (PI) and time to PI in the soft tissue and callus and by counting the vascular signals. Vascular signals from the soft tissue were detected on power Doppler and CEUS on day 2. Significantly more vascular signals were detected by CEUS than by power Doppler. On CEUS, PI in the surrounding soft tissue was markedly increased after the fracture line appeared indistinctively changed on radiography in all dogs. In the cast-applied dogs, vascular signals from the periosteal and endosteal callus were detected on CEUS before mineralized callus was observed on radiography. CEUS was useful in assessing the vascularity of soft tissue and callus, particularly in indirect fracture healing, and provided indications of a normally healing fracture.

[Diamond concept for treatment of nonunions and bone defects]

Nonunions represent a very heterogeneous, rare and sometimes very complex disease picture. The causes, localization and degree of expression show a very high variability, which makes it difficult to establish uniform treatment standards. Nevertheless, the process of bone healing is subject to some essential factors, which should be ensured for a successful treatment. Over the years these factors have been better researched and were taken into consideration for the diamond concept, which was first published by Giannoudis et al. in 2007. This provides the physician with a concept that does not neglect the heterogeneity of the disease picture and is an aid to decision making for the treatment regimen in individual cases in order to guarantee the best biological and mechanical conditions. The diamond concept is nowadays widely used and many studies have already demonstrated a successful application. It must be understood as a framework, in which the various treatment options available (bone substitute materials, mesenchymal stem cells, osteosynthesis procedures etc.) are incorporated into the individual factors and therefore provides the physician with a certain freedom of choice in the selection of tools. Additionally, it is not a rigid corset and subject to medical scientific progress in its factors, so that it is exciting to see which new developments will be incorporated in the future.

Perspective on optical imaging for functional assessment in musculoskeletal extremity trauma surgery

SIGNIFICANCE

Extremity injury represents the leading cause of trauma hospitalizations among adults under the age of 65 years, and long-term impairments are often substantial. Restoring function depends, in large part, on bone and soft tissue healing. Thus, decisions around treatment strategy are based on assessment of the healing potential of injured bone and/or soft tissue. However, at the present, this assessment is based on subjective clinical clues and/or cadaveric studies without any objective measure. Optical imaging is an ideal method to solve several of these issues.

AIM

The aim is to highlight the current challenges in assessing bone and tissue perfusion/viability and the potentially high impact applications for optical imaging in orthopaedic surgery.

APPROACH

The prospective will review the current challenges faced by the orthopaedic surgeon and briefly discuss optical imaging tools that have been published. With this in mind, it will suggest key research areas that could be evolved to help make surgical assessments more objective and quantitative.

RESULTS

Orthopaedic surgical procedures should benefit from incorporation of methods to measure functional blood perfusion or tissue metabolism. The types of measurements though can vary in the depth of tissue sampled, with some being quite superficial and others sensing several millimeters into the tissue. Most of these intrasurgical imaging tools represent an ideal way to improve surgical treatment of orthopaedic injuries due to their inherent point-of-care use and their compatibility with real-time management.

CONCLUSION

While there are several optical measurements to directly measure bone function, the choice of tools can determine also the signal strength and depth of sampling. For orthopaedic surgery, real-time data regarding bone and tissue perfusion should lead to more effective patient-specific management of common orthopaedic conditions, requiring deeper penetrance commonly seen with indocyanine green imaging. This will lower morbidity and result in decreased variability associated with how these conditions are managed.

Quantitative Assessment of Tumor Cell Proliferation in Brain Gliomas with Dynamic Contrast-Enhanced MRI

RATIONALE AND OBJECTIVES

This study aimed to investigate whether volume transfer constant (K^trans) and volume of extravascular extracellular space per unit volume of tissue (V_e) derived from dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) could quantitatively assess the tumor proliferation index (Ki-67) of gliomas noninvasively.

MATERIALS AND METHODS

The preoperative DCE MRI data of 69 patients with pathologically confirmed glioma (28, 8, and 33 cases in grades Ⅱ, Ⅲ, and Ⅳ) were retrospectively reviewed. The maximal K^trans and V_e were measured in the tumor body. The immunohistochemistry was used to detect the expression of Ki-67 proteins in glioma specimens. The Mann-Whitney U test was applied to analyze the differences in K^trans, V_e, and Ki-67 index across histologically defined glioma grades. Spearman correlation was performed between K^trans, V_e, and Ki-67 index. The receiver operating characteristic curve analysis was used to determine the cutoff values of K^trans and V_e in distinguishing different Ki-67 index expression levels.

RESULTS

K^trans, V_e, and Ki-67 index of grade Ⅱ (0.027 min^-1, 0.065, 4.04%) were significantly lower than those of grade Ⅲ (0.093 min^-1, 0.297, 25.13%) and Ⅳ (0.100 min^-1, 0.299, 25.37%). Both K^trans and V_e significantly correlated with the Ki-67 index in all tumors and high-grade gliomas (HGGs, grade Ⅲ and Ⅳ). The receiver operating characteristic curve analysis revealed that the cutoff values for K^trans (0.079 min^-1) and V_e (0.249) provided the best combination of sensitivity and specificity to distinguish the gliomas with high Ki-67 index from those with low Ki-67 index.

CONCLUSION

The DCE MRI-derived parameters were valuable in assessing the tumor cell proliferation in HGG noninvasively.

Evaluation of the clinical use of the ETN PROtect® in non-union therapy

INTRODUCTION

Non-union of a long bone fracture remains a challenge in orthopaedic and trauma surgery. In the current study, we sought to determine the clinical effectiveness of tibial non-union treatment utilizing an antibiotic-coated intramedullary nail (Expert Tibia Nail (ETN) PROtect®) regarding prevention and treatment of infection and the clinical outcome.

PATIENTS AND METHODS

36 patients suffering from tibial non-unions that were treated with the ETN PROtect® in the course of non-union treatment between February 2010 and March 2015 were included in this clinical observational study. Clinical and radiological examinations were performed preoperatively as well as 4, 6 and 12 weeks and 6 and 12 months postoperatively as part of a standardized follow-up program. Data regarding perioperative complications, weight-bearing capacity, radiological signs of consolidation and subjective health status were assessed at each time point. Laboratory parameters such as C-reactive protein (CRP) and leukocyte count were collected preoperatively in order to assess the patients' risk profile for infection.

RESULTS

Patients had an average of 6.2 previous surgeries and 22 patients (61.1%) had a positive bacterial culture from intraoperatively removed tissue during the first operative treatment. 29 patients (80.6%) achieved full weight-bearing after an average of 7.7 months, furthermore 80.6% of patients achieved osseous consolidation. 3 deep infections occurred, including one amputation. Subjective health status increase based on the SF-12 questionnaire during our follow-up program.

CONCLUSION

The results from the current study indicate that the use of the ETN PROtect® in the applied non-union therapy has a high clinical effectiveness regarding osseous consolidation and time to weight bearing. In addition, the use of gentamicin-coated nails in the treatment of tibial non-unions might contribute to both successful treatment of the underlying infection and prevention of perioperative infection. The gentamicin-coated nail may serve as a beneficial adjunct treatment in the applied non-union therapy in addition to all established techniques in the treatment of infected non-unions.

Bone marrow perfusion measured with dynamic contrast enhanced magnetic resonance imaging is correlated to body mass index in adults

Bone marrow metabolism is complex and far from being fully understood. Novel aspects, such as the roles of bone marrow adiposity and vascularisation in bone metabolism currently attract attention. There is also a growing interest in the influence obesity might have on bone metabolism. Our objective was to determine the effect of BMI on bone marrow perfusion parameters using dynamic contrast-enhanced magnetic resonance imaging. This prospective monocentric study was approved by our local Ethics committee. Written consent was obtained. The right hip of 59 adults under 60years old (mean age 37.5) was imaged with a dynamic 3D T1 spoiled gradient echo magnetic resonance imaging sequence. Mean BMI was 24.8 (+/-4.4). Perfusion parameters were measured in the acetabulum and femoral neck, in the greater trochanter, in the femoral head epiphysis and in the subcutaneous adipose tissue. Associations between perfusion parameters and BMI were studied using a linear mixed model adjusted for age and sex effects. Our results showed that as the BMI increased, the exchanges between blood and bone marrow appeared more important (increased K_trans and K_ep values, p=0.018 and p=0.002 respectively) and the intramedullary blood flow appeared increased (lower time to peak values, p=0.0002). In the subcutaneous fat, as the BMI increased, the vascularization decreased (lower area under the curve and initial slope values, p=0.019 and p=0.013 respectively). These results suggest that there is a relation between bone marrow perfusion and BMI, and that subcutaneous fat and bone marrow fat have different microvascular behaviours. Researchers must be aware of the effect of BMI on bone marrow perfusion parameters when they build a MR research protocol and analyse their data. A better understanding of these findings may provide the basis for the management of obesity-related bone changes.

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for the prediction of non-union consolidation

INTRODUCTION

Non-union perfusion can be visualized with dynamic contrast-enhanced (DCE) MRI. This study evaluated DCE-MRI to predict non-union consolidation after surgery and detect factors that affect bone healing.

MATERIALS AND METHODS

Between 2010 and 2015 non-union perfusion was prospectively quantified in 205 patients (mean age, 51.5 years, 129 men, 76 women) before intervention and at 6, 12, 26, 52 and more weeks follow-up. DCE-MRI results were related to the osseous consolidation, the ability to predict successful outcome was estimated by ROC analysis. The relevance of the body mass index (BMI) and the non-union severity score (NUSS) to the healing process was assessed.

RESULTS

Tibial (n=99) and femoral (n=76) non-unions were most common. Consolidation could be assessed in 169 patients, of these 103 (61%) showed eventual healing and demonstrated higher perfusion than in failed consolidation at 6 (p=0.0226), 12 (p=0.0252) and 26 (p=0.0088) weeks follow-up. DCE-MRI at 26 weeks follow-up predicted non-union consolidation with a sensitivity of 75% and a specificity of 87% (false classification rate 19%). Higher BMI (p=0.041) and NUSS (p<0.0001) were associated with treatment failure.

CONCLUSIONS

DCE-MRI perfusion analysis after non-union surgery predicts successful outcome and could facilitate the decision of early intervention. NUSS and BMI are important prognostic factors concerning consolidation.

Dynamic Contrast-Enhanced Sonography and Dynamic Contrast-Enhanced Magnetic Resonance Imaging for Preoperative Diagnosis of Infected Nonunions

OBJECTIVES

Bone regeneration depends on perfusion of the fracture tissue, whereby hypervascularity is associated with infection, which itself causes nonunions. To date, nonunion perfusion has not been assessed with contrast-enhanced sonography. The aim of this study was to evaluate the potential of contrast-enhanced sonography in the analysis of nonunion tissue perfusion.

METHODS

Nonunion vascularity of 31 patients before revision surgery was prospectively examined with qualitative contrast-enhanced sonography and dynamic contrast-enhanced magnetic resonance imaging (MRI). Time-intensity curves from 2-minute contrast-enhanced sonographic video clips were generated, and parameters such as wash-in rate, rise time, and peak enhancement were quantified. On dynamic contrast-enhanced MRI, the initial area under the enhancement curve was quantified. Preoperative radiographs, computed tomograms, the clinical nonunion score, laboratory infection features, as well as contrast-enhanced sonographic and dynamic contrast-enhanced MRI perfusion were correlated with microbiological results from the nonunion tissue.

RESULTS

Both qualitative and quantitative contrast-enhanced sonography showed significant differences between infected and aseptic nonunions (P = .015 and .020). The qualitative dynamic contrast-enhanced MRI analysis was not significant (P= .244), but after quantification, a strong correlation (P = .007) with microbiological results was noted. A receiver operating characteristic analysis calculated ideal cutoff values for quantitative contrast-enhanced sonography and dynamic contrast-enhanced MRI so that their combination detected infected nonunions with sensitivity and specificity of 88.9% and 77.3%, respectively. Clinical, radiologic, and laboratory examinations did not correlate with microbiological results (P > .05).

CONCLUSIONS

Contrast-enhanced sonography can visualize the vascularity of nonunions in real time, while quantification software allows for a semiobjective evaluation of bone perfusion. The correlations of both quantitative contrast-enhanced sonography and dynamic contrast-enhanced MRI with microbiological results show their high value for differentiation of infected from aseptic nonunions.

Treatment of atrophic tibia non-unions according to 'diamond concept': Results of one- and two-step treatment

BACKGROUND

The successful treatment of atrophic tibia non-unions and tibia non-unions with large bone defects or infections is a major challenge in orthopedic and trauma surgery. This article evaluates the use of the 'diamond concept' using a one-step or two-step procedure according to 'Masquelet technique' in the treatment of atrophic tibia non-unions.

METHODS

Between February 2010 and March 2014, 102 patients with atrophic non-unions were treated according to the 'diamond concept' in our center. Ninety-nine were available for follow-up. Forty-nine received a one-step treatment (Group 1, G1) and 50 patients received a two-step treatment according to the 'Masquelet technique' (Group 2, G2). Clinical and radiological parameters were measured preoperatively as well as 4, 6, and 12 weeks and 6 and 12 months postoperatively. In order to evaluate the subjective health of patients, we used the SF-12 questionnaire. Data analysis was performed one year after treatment.

RESULTS

The rate of consolidation in G1 was 84% and 80% in G2. The time to heal in G2 was 8.6 ± 2.9 months, which is significantly longer than in G1 being 6.9 ± 3.1 months. In comparison patients in G1/G2 had an average of 3.2/6.7 previous major surgeries. In G1, 4 of 8 patients who did not heal successfully showed positive intraoperative cultures. In G2, 26 patients (52%) initially presented with positive cultures. The results of the SF-12 questionnaire improved in both groups during the postoperative follow-up, but showed no significant differences between groups. In 29 patients a gentamycin-coated nail was used for reosteosynthesis. These patients showed by trend a lower rate of complications at a higher rate of consolidation.

CONCLUSIONS

Our study showed that the 'diamond concept' is a suitable method for safely and effectively treating non-unions with large defects or infections. The use of an antibiotic-coated nail provides a therapeutic benefit. For large bone defects of infected non-unions the two-step procedure after Masquelet is an efficient way to eradicate the infection and treat the bone defect successfully.

Functional imaging of the musculoskeletal system

Functional imaging, which provides information of how tissues function rather than structural information, is well established in neuro- and cardiac imaging. Many musculoskeletal structures, such as ligaments, fascia and mineralized bone, have by definition a mainly structural role and clearly don't have the same functional capacity as the brain, heart, liver or kidney. The main functionally responsive musculoskeletal tissues are the bone marrow, muscle and nerve and, as such, magnetic resonance (MR) functional imaging has primarily addressed these areas. Proton or phosphorus spectroscopy, other fat quantification techniques, perfusion imaging, BOLD imaging, diffusion and diffusion tensor imaging (DTI) are the main functional techniques applied. The application of these techniques in the musculoskeletal system has mainly been research orientated where they have already greatly enhanced our understanding of marrow physiology, muscle physiology and neural function. Going forwards, they will have a greater clinical impact helping to bridge the disconnect often seen between structural appearances and clinical symptoms, allowing a greater understanding of disease processes and earlier recognition of disease, improving prognostic prediction and optimizing the monitoring of treatment effect.

Contrast-enhanced ultrasonography to assess blood perfusion of skeletal muscles in normal dogs

This study evaluated perfusion of skeletal muscle using contrast enhanced ultrasonography in humerus, radius, femur and tibia in normal dogs. Contrast enhanced ultrasonography for each region was performed after injecting 0.5 mL and 1 mL of contrast medium (SonoVue) in every dog. Blood perfusion was assessed quantitatively by measuring the peak intensity, time to the peak intensity and area under the curve from the time-intensity curve. Vascularization in skeletal muscle was qualitatively graded with a score of 0-3 according to the number of vascular signals. A parabolic shape of time-intensity curve was observed from muscles in normal dogs, and time to the peak intensity, the peak intensity and area under the curve of each muscle were not significantly different according to the appendicular regions examined and the dosage of contrast agent administered. This study reports that feasibility of contrast enhanced ultrasonography for assessment of the muscular perfusion in canine appendicular regions.