Imaging in Rheumatology / Radiology
MRI and ultrasonography are highly sensitive modalities and their use can improve diagnostic criteria for rheumatoid arthritis.
The concept of subclinical inflammation has been established by MRI and ultrasonography, and is evident from the earliest phases of pre-rheumatoid arthritis to those with sustained clinical remission.
MRI studies of cartilage composition have confirmed a close relationship between synovitis to cartilage proteoglycan loss.
As evidence on the predictive validity of early MRI findings for radiographic progression and functional outcomes accumulates, MRI is increasingly being employed in outcome assessment in rheumatoid arthritis therapy trials.
Reduced ultrasonography joint scores are being developed and validated to improve feasibility of both diagnosis and monitoring in routine clinical care.
Mathew AJ, Danda D, Conaghan PG. "MRI and ultrasound in rheumatoid arthritis," Curr Opin Rheumatol. 2016 Feb 26. [Epub ahead of print] PMID: 26927442
Esperanza Naredo, Lara Valor, Inmaculada De la Torre, et. al. "Predictive Value of Doppler Ultrasound-Detected Synovitis in Relation to Successful Tapering of Biology Therapy in Patients with Rheumatoid Arthritis," Rheumatology (Oxford, England) (Impact Factor: 4.48). 03/2015; 73(Suppl 2). DOI: 10.1093/rheumatology/kev006
Haavardsholm EA, Aga AB, Olsen IC, Hammer HB, Uhlig T, et. al. "Aiming for Remission in Rheumatoid Arthritis: Clinical and Radiographic Outcomes from a Randomized Controlled Strategy Trial Investigating the Added Value of Ultrasonography in a Treat-to-Target Regimen," Arthritis Rheumatol. 2015; 67 (suppl 10).
Radiography is an imaging technique that uses x-rays to create images of a region of interest in the body. Ultrasonography (US) is an imaging technique that uses high-frequency ultrasound waves to create images in real time. Computed tomography (CT) is an imaging technique that uses x-rays to create tomographic images. Magnetic resonance imaging (MRI) is an imaging technique that uses magnetism and radiofrequency waves to create tomographic images. Planar scintigraphy, single photon emission computed tomography (SPECT), and positron emission tomography (PET) are the nuclear medicine molecular imaging techniques available. They are used to image the distribution and accumulation of an administered radiotracer in organs/tissues of the body; the spatial distribution and amount of accumulation depend on the properties of the radiotracer and the disease states present in the involved organs.
Density, echogenicity, attenuation, and signal intensity are the descriptors of how bright or dark tissues are on radiography, US, CT, and MR images, respectively. Standardized uptake value (SUV) is a quantitative measure of PET radiotracer uptake in a tissue of interest.
If fluid has very high signal intensity on an MR image, then the image is likely T2-weighted. If fluid has low signal intensity on an MR image, then the image is likely T1-weighted. An easy reference organ is the signal intensity of cerebrospinal fluid on MR images; if it is bright, then the image is likely a T2-weighted image.
Distinguishing physiologic from allergic-like contrast reactions is important, as patients with physiologic reactions do not require future corticosteroid premedication, whereas those with allergic-like reactions may need future corticosteroid premedication
Intravascular gadolinium-based contrast material is contraindicated for use in pregnant patients. However, iodinated contrast material can be administered to pregnant or potentially pregnant patients when needed for diagnostic purposes.
Dose optimization is often summarized as ALARA (“as low as reasonably achievable”), but it dictates that the radiologic examination should be tailored to the clinical question, patient size, and anatomy of interest.
Be aware of the major blind spots on frontal chest radiography where nodules and masses are easily overlooked: the lung apices where the clavicles and ribs overlap, the hilar regions where vascular structures abound, the retrocardiac region, and the lung bases where there is superimposition with the upper abdominal soft tissue
Opacity is a nonspecific descriptor that implies a region that attenuates x-rays to a greater degree than surrounding tissues, and it can be due to any abnormality overlying or within the lung. Consolidation, however, specifically refers to an alveolar filling process, which opacifies the lung.
Imaging findings of reactivation tuberculosis (TB) may include upper lung zone predominant focal consolidation or nodular opacities, areas of cavitation, centrilobular, acinar, and/or tree-in-bud nodular opacities, interstitial miliary nodules, bronchiectasis, and thoracic lymphadenopathy (often with areas of central necrosis).
The imaging modality of choice for a patient with acute head trauma is an unenhanced brain CT scan.
Time is BRAIN. Rapid diagnosis of ischemic stroke and prompt initiation of treatment are critical for a good outcome. Diffusion-weighted imaging (DWI) is the most sensitive MRI sequence for detection of acute stroke.
Necrotizing fasciitis is a surgical emergency, requiring prompt diagnosis and treatment. Its diagnosis, while primarily clinical, also rests in the identification of soft tissue emphysema. Other suggestive imaging features include fascial plane thickening, edema, or enhancement, as well as edema, phlegmon, or abscess formation in subjacent muscles.
Tennis elbow (lateral epicondylitis) and golfer’s elbow (medial epicondylitis) are due to inflammation of the common extensor and common flexor tendons, respectively.
Ligament and tendon injuries are seen as full- or partial-thickness high signal intensity foci in the normally low signal structures on T2-weighted images.
MRI is the examination of choice for evaluation of suspected hip fractures when radiography fails to reveal the cause of hip pain, because it is a highly sensitive and specific modality for detection of radiographically occult fractures and is more sensitive than CT for detection of other possible causes of hip pain such as soft tissue injuries.
A meniscal tear is present when either abnormal signal intensity within a meniscus extending to the articular surface on two contiguous slices or abnormal meniscal morphology is visualized.
Metaphyseal corner fractures or bucket-handle fractures have high specificity for child abuse. Posterior rib fractures, fractures of the scapula, spinous process, or sternum, vertebral compression fractures, complex skull fractures, and multiple fractures of different ages are suggestive of child abuse as well. Subdural hematomas, particularly when interhemispheric or seen in the posterior fossa/tentorial locations, are suspicious for head trauma related to shaken infant syndrome.