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Contrast-enhanced ultrasound (CEUS) has emerged as a valuable imaging modality that complements and enhances standard vascular ultrasound imaging. Ultrasound contrast agents are gas-filled microbubbles that are injected intravenously and serve as intravascular tracers. Based on the properties to enhance and to quantify the macro- and microcirculation down to the capillary perfusion level in different vascular territories and organs, CEUS imaging has the potential to improve the diagnostic performance in the detection and characterisation of various vascular disorders reviewed in this article. In carotid atherosclerotic disease, CEUS imaging provides additional information on plaque vulnerability by illustrating the presence and extent of intraplaque neovascularisation. This new imaging modality may be helpful for further risk stratification of arteriosclerotic lesions and for detecting patients at risk for vascular events, eventually leading to more specific individually tailored therapeutic recommendations. CEUS imaging is also a helpful tool for the diagnosis and for monitoring of inflammatory vascular diseases. It increases the diagnostic performance of ultrasound in detecting inflammatory changes of the vessel wall such as hypervascularisation and hyperaemia. Changes in vessel wall enhancement may also reflect the response to anti-inflammatory therapy. Moreover, CEUS imaging is also a valuable tool for the assessment of the microcirculation and the tissue perfusion in solid organs including native and transplanted kidneys. The technique provides more accurate information on perfusion deficits of the parenchyma in patients with kidney infarction, necrosis or graft dysfunction. CEUS also has great potential in the assessment of the microcirculation of the skeletal muscle, particularly in patients with peripheral artery disease or diabetic microangiopathy. In the future, the use of targeted on site microbubbles could further enhance and expand the diagnostic capabilities of current vascular ultrasound by assessing specific molecular processes that play a role in the pathophysiology of vascular diseases. Furthermore, ultrasound-directed, site-specific drug and gene delivery using microbubble contrast agents could gain great clinical value in the future. The combination of CEUS for diagnosis and therapy will provide unique opportunities for vascular clinicians to image the microcirculation and directly treat vascular diseases.

Purpose: To prospectively compare calf muscle BOLD MRI with transcutaneous oxygen pressure (TcPO2 ) measurement in patients with systemic sclerosis (SSc) and healthy volunteers and thereby get insight into the pathogenesis of vasculopathy in this connective tissue disorder., Materials and Methods: Twelve patients with SSc (6 women and 6 men, mean age 53.5 ± 10.0 years) and 12 healthy volunteers (4 men and 8 women, mean age 47 ± 12.1 years) were examined using muscle BOLD MRI and TcPO2. A cuff compression at mid-thigh level was performed to provoke ischemia and reactive hyperemia. BOLD measurements were acquired on a 3 Tesla whole body-scanner in the upper calf region using a multi-echo EPI-sequence with four echo-times (TE: 9/20/31/42 ms) and a repetition time of 2 s. Empirical cross-correlation analysis depending on time lags between BOLD- and TcPO2-measurements was performed., Results: Maximal cross-correlation of BOLD T2*- and TcPO2-measurements was calculated as 0.93 (healthy volunteers) and 0.90 (SSc patients) for a time lag of approximately 40 s. Both modalities showed substantial differences regarding time course parameters between the SSc patients and healthy volunteers., Conclusion: Skeletal muscle BOLD MRI correlated very well with TcPO2 . T2* changes seem to reflect reoxygenation deficits in deeper muscle tissue of SSc patients., (Copyright © 2013 Wiley Periodicals, Inc.)

Introduction: Muscle symptoms in systemic sclerosis (SSc) may originate from altered skeletal muscle microcirculation, which can be investigated by means of blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI)., Methods: After ethics committee approval and written consent, 11 consecutive SSc patients (5 men, mean age 52.6 years, mean SSc disease duration 5.4 years) and 12 healthy volunteers (4 men, mean age 45.1 years) were included. Subjects with peripheral arterial occlusive disease were excluded. BOLD MRI was performed on calf muscles during cuff-induced ischemia and reactive hyperemia, using a 3-T whole-body scanner (Verio, Siemens, Erlangen, Germany) and fat-suppressed single-short multi-echo echo planar imaging (EPI) with four different effective echo times. Muscle BOLD signal time courses were obtained for gastrocnemius and soleus muscles: minimal hemoglobin oxygen saturation (T2*min) and maximal T2* values (T2*max), time to T2* peak (TTP), and slopes of oxygen normalization after T2* peaking., Results: The vast majority of SSc patients lacked skeletal muscle atrophy, weakness or serum creatine kinase elevation. Nevertheless, more intense oxygen desaturation during ischemia was observed in calf muscles of SSc patients (mean T2*min -15.0%), compared with controls (-9.1%, P = 0.02). SSc patients also had impaired oxygenation during hyperemia (median T2*max 9.2% vs. 20.1%, respectively, P = 0.007). The slope of muscle oxygen normalization was significantly less steep and prolonged (TTP) in SSc patients (P<0.001 for both). Similar differences were found at a separate analysis of gastrocnemius and soleus muscles, with most pronounced impairment in the gastrocnemius., Conclusions: BOLD MRI demonstrates a significant impairment of skeletal muscle microcirculation in SSc.