Magnetic resonance imaging (MRI) has an established role in the assessment of degenerative musculoskeletal conditions. However, conventional supine MRI findings often correlate poorly with clinical findings. Some patients experience accentuated back pain in the weight-bearing position. Therefore, supine MRI may underestimate the severity of degenerative spine findings. To try and improve the clinical validity of spine imaging, axial loading devices have been used with conventional supine MR imaging to simulate loading of the upright spine. More recently, upright weight-bearing MRI systems (0.25-0.6 T) were introduced, allowing images to be obtained in the standing or seated weight-bearing position and even during upright flexion or extension, rotation, or bending. Some scanners even enable capturing of real-time spinal movement. This review addresses the technical aspects and potential challenges of weight-bearing MRI, both in clinical practice and research.
Symptoms of degenerative lumbar spinal stenosis include back pain, radiculopathy, claudication, and muscular fatigue that tend to be predominant in the standing position or during walking. Lumbar spondylolisthesis is also a well-known cause of spinal stenosis, lateral recess, and neural foraminal narrowing that tends to become more severe in the upright position. This indicates a functional positional component of both spinal stenosis and spondylolisthesis. Lumbar spinal stenosis and spondylolisthesis are typically evaluated by magnetic resonance imaging (MRI) performed in the supine position with a pillow under the patient’s lower limbs that slightly flexes the lumbar spine and ameliorates symptoms. Because these two entities tend to be aggravated in the upright position, it seems rational to also consider performing diagnostic imaging in these patients in the upright position. This article reviews the use of weight-bearing MRI for lumbar spinal stenosis and spondylolisthesis.
Overloading of tendon tissue with resulting chronic pain (tendinopathy) is a common disorder in occupational-, leisure- and sports-activity, but its pathogenesis remains poorly understood. To investigate the very early phase of tendinopathy, Achilles and patellar tendons were investigated in 200 physically active patients and 50 healthy control persons. Patients were divided into three groups: symptoms for 0-1 months (T1), 1-2 months (T2) or 2-3 months (T3). Tendinopathic Achilles tendon cross-sectional area determined by ultrasonography (US) was ~25% larger than in healthy control persons. Both Achilles and patellar anterior-posterior diameter were elevated in tendinopathy, and only later in Achilles was the width increased. Increased tendon size was accompanied by an increase in hypervascularization (US Doppler flow) without any change in mRNA for angiogenic factors. From patellar biopsies taken bilaterally, mRNA for most growth factors and tendon components remained unchanged (except for TGF-beta1 and substance-P) in early tendinopathy. Tendon stiffness remained unaltered over the first three months of tendinopathy and was similar to the asymptomatic contra-lateral tendon. In conclusion, this suggests that tendinopathy pathogenesis represents a disturbed tissue homeostasis with fluid accumulation. The disturbance is likely induced by repeated mechanical overloading rather than a partial rupture of the tendon.
In this prospective study, dual-energy CT and MRI had a similarly high sensitivity and specificity in helping detect radiographically negative wrist fractures. Dual-energy CT had a high sensitivity and a moderate specificity in the detection of bone marrow edema of the wrist. Dual-energy CT had high sensitivity and specificity in depicting fractures of the wrist in patients with suspected wrist fractures and negative findings on radiographs.