Clinical implications of skeletal muscle blood-oxygenation-level-dependent (BOLD) MRI

Blood-oxygenation-level-dependent (BOLD) contrast in magnetic resonance (MR) imaging of skeletal muscle mainly depends on changes of oxygen saturation in the microcirculation. In recent years, an increasing number of studies have evaluated the clinical relevance of skeletal muscle BOLD MR imaging in vascular diseases, such as peripheral arterial occlusive disease, diabetes mellitus, and chronic compartment syndrome. BOLD imaging combines the advantages of MR imaging, i.e., high spatial resolution, no exposure to ionizing radiation, with functional information of local microvascular perfusion. Due to intrinsic contrast provoked via changes in hemoglobin oxygen saturation, it is a safe and easy applicable procedure on standard whole-body MR devices. Therefore, BOLD MR imaging of skeletal muscle is a potential new diagnostic tool in the clinical evaluation of vascular, inflammatory, and muscular pathologies. Our review focuses on the current evidence concerning the use of BOLD MR imaging of skeletal muscle under pathological conditions and highlights ways for future clinical and scientific application

ECG-triggered non-enhanced MR angiography of peripheral arteries in comparison to DSA in patients with peripheral artery occlusive disease

Object: The purpose of this study was to evaluate peripheral non-enhanced-MRA (NE-MRA) acquired with a 3D Turbo Spin Echo sequence with electrocardiographt (ECG) triggering in comparison to Digital Subtraction Angiography (DSA) as the gold standard in symptomatic peripheral artery occlusive disease (PAOD) patients. Materials and methods: This IRB approved prospective study included 23 PAOD patients from whom three patients had to be excluded. The remaining 20 subjects were included in the analysis (15 male; mean age 62.4±15.3years). The patients first underwent DSA followed by NE-MRA on a 1.5-T whole body scanner within 24h after the DSA study. A NATIVE (Non-contrast Angiography of the Arteries and Veins) SPACE (Sampling Perfection with Application Optimized Contrast by using different flip angle Evolution) sequence at four levels (pelvis, upper leg, knee region and lower leg) was acquired. For evaluation purposes, subtracted standardized MIP (maximum intensity projection) images were generated from the NE-MRA data sets. Qualitative assessment of NE-MRA images in reference to the corresponding DSA images, as well as blinded stenosis grading of preselected segments in NE-MRA images were performed by two experienced readers. Image quality in 95 corresponding arterial segments was rated from 1 (good) to 4 (inadequate) directly comparing the NE-MRA with the corresponding DSA segment as the gold standard. Blinded stenosis grading consisted of 66 preselected stenoses rated from 1 (90%) in NE-MRA which were compared to the grade in the corresponding DSA. Results: The mean image quality of NE-MRA in comparison to DSA was 2.7±1.1 (reader 1) and 3.0±1.0 (reader 2). The kappa value indicating interobserver agreement was 0.34; readers 1 and 2 rated the image quality as good in 21% and 3%, sufficient in 19% and 41%, limited in 29% and 14% and inadequate in 31% and 42%, respectively. Stenosis graduation revealed significantly higher grades in NE-MRA (reader 1: 3.0±0.7, p<0.001 and reader 2: 3.1+0.8, p<0.001) compared to DSA (mean value DSA 2.7±0.8). The kappa value indicating interobserver agreement concerning stenosis grading was 0.59. Conclusion: NE-MRA revealed a relatively high number of inadequate quality segments. This is in line with recently published comparable studies of the similar SPACE NE-MRA techniques. Further advance of NE-MRA techniques remains desirable for patients with PAO

Clinical oncologic applications of PET/MRI: a new horizon

Abstract: Positron emission tomography/magnetic resonance imaging (PET/MRI) leverages the high soft-tissue contrast and the functional sequences of MR with the molecular information of PET in one single, hybrid imaging technology. This technology, which was recently introduced into the clinical arena in a few medical centers worldwide, provides information about tumor biology and microenvironment. Studies on indirect PET/MRI (use of positron emission tomography/computed tomography (PET/CT) images software fused with MRI images) have already generated interesting preliminary data to pave the ground for potential applications of PET/MRI. These initial data convey that PET/MRI is promising in neuro-oncology and head &amp; neck cancer applications as well as neoplasms in the abdomen and pelvis. The pediatric and young adult oncology population requiring frequent follow-up studies as well as pregnant woman might benefit from PET/MRI due to its lower ionizing radiation dose. The indication and planning of therapeutic interventions and specifically radiation therapy in individual patients could be and to a certain extent are already facilitated by performing PET/MRI. The objective of this article is to discuss potential clinical oncology indications of PET/MRI

Endovascular Treatment of Pulmonary Arteriovenous Malformations: How We Do It

Pulmonary arteriovenous malformation (PAVM) is a rare disease disproportionally affecting patients with hereditary hemorrhagic telangiectasia and may be associated with other pulmonary or infectious etiologies. Respiratory symptoms are the most common, including dyspnea, hypoxemia, and hemoptysis. Due to the impairment of normal pulmonary filtration function, patients with PAVM are at risk for embolic events, ranging from ischemic strokes to brain abscesses. More importantly, PAVM can enlarge over time or with physiological changes, which may lead to catastrophic hemorrhages and increased embolization risks. From imaging perspective, echocardiography with contrast bubbles and computed tomography can both be used to diagnose PAVMs with high sensitivity and specificity. Treatment modalities have evolved from invasive surgeries to transluminal catheter-based interventions. In recent decades, the evolution of interventional techniques and equipment has resulted in a high technical success rate for the treatment of PAVMs. Here, we present the interventional PAVM treatment protocol at our institution

Isolated traumatic pectoralis minor tendon tear in a young adult diagnosed with MRI

This is a rare case of an isolated pectoralis minor partial-thickness tendon tear in a 24-year-old man who was involved in a major trauma. The purpose of this paper is to report the clinical signs, symptoms, cross-sectional imaging findings, and management of an isolated pectoralis minor tendon tear. Furthermore, this case represents a novel traumatic mechanism of injury, as opposed to the classic sports-related pectoralis minor tendon tear injury. The current limited body of literature on isolated pectoralis minor tendon tears is reviewed. Keywords: Pectoralis minor, Trauma, MVA, MRI, C

Detection of adventitial vasa vasorum and intraplaque neovascularization in carotid atherosclerotic lesions with contrast-enhanced ultrasound and their role in atherosclerosis

INTRODUCTION: The development of new surrogate markers of atherosclerosis is a crucial goal in the clinical setting, as they may allow physicians to recognize unstable lesions early and identify individuals with vulnerable or unstable lesions who bear an increased risk of future cardio--and cerebrovascular complications. These surrogate markers should be capable of being measured noninvasively using safe and reliable methods. Recently, Nambi et al. demonstrated how the combined measurement of carotid intima media thickness (CIMT) and occurrence of carotid plaques improves the risk prediction of cardiovascular outcomes. These results confirm the value of carotid ultrasound (US) when combined with traditional Framingham risk factors in assessing a patient's risk for atherosclerotic disease. Contrast-enhanced ultrasound (CEUS) is a new imaging approach that is evolving and may become a standard clinical tool for further atherosclerotic risk stratification in the future. The contrast agents used in US imaging are safe, commercially available, and approved for use in echocardiography by the FDA. Thus, CEUS is technically feasible with existing approved commercial equipment and can be performed at the bedside or in an outpatient setting. However, US contrast agents are not yet approved by the FDA for visualization and assessment of the carotid artery and its associated pathologies. The cost effectiveness of CEUS has been shown in the context of gastrointestinal imaging, and CEUS of carotid atherosclerotic lesions is emerging as an approach to complement unenhanced US imaging. By providing the direct visualization of adventitial vasa vasorum (VV) and intraplaque neovascularization, CEUS is capable of depicting two new surrogate markers of atherosclerosis - namely, adventitial VV and intraplaque neovascularization