When imaging through both hips is indicated, the coronal images are performed straight rather than oblique, and images extend through the anterior and posterior muscle groups on both sides. Likewise, sagittal imaging through the joint may be limited to the greater trochanter laterally and the medial acetabular wall medially when the pathology is intra-articular, but more often imaging through the entire area is recommended to evaluate the adjacent soft tissues. In many cases the clinical history is not specific, or the pathology may be extra-articular, and it is therefore prudent to enlarge the FOV to include all of the muscle groups. If the clinical indication is to evaluate for intra-articular pathology, coronal images through the iliopsoas anteriorly and sciatic nerve posteriorly are often sufficient. Detailed clinical information about the patient’s symptoms is extremely helpful in establishing an appropriate protocol.įor single hip imaging, coronal images should extend through the entire joint. Some patients may not be able to hold still for extended periods of time, so it is often important to perform the most important imaging sequences early in an imaging protocol. Surface coils used for imaging of the hip joint and surrounding structures are flat or flexible so that they may be placed over the hip of interest. It is often worthwhile to obtain one coronal image through both hips with a body coil, which will serve as a guide for subsequent sequences, and also reveal whether there are bilateral or diffuse abnormalities. In a patient with unilateral hip pain with systemic disease such as sickle cell disease (SCD), a dedicated surface coil positioned over the painful hip will provide high-quality images of the hip while a single, additional sequence with a larger, body matrix coil may provide important additional information about the surrounding pelvis and contralateral hip (Fig. In some instances it may be useful to image one patient using several coils, depending on the indication. One must consider whether the benefit of increasing the FOV to include the contralateral hip outweighs the loss of resolution that will accompany the increase in coverage (Fig. Larger body coils allow for increased SNR and more uniform signal intensity throughout the image, though with decreased spatial resolution. Localized surface coils allow for improved spatial resolution and better detail of the anatomic structures such as femoral head, joint capsule, cartilage, and labrum (Fig. Regional coils, such as phased-array torso, cardiac, or body matrix coils, should be considered when imaging of the entire pelvis is indicated, at the expense of high-resolution imaging of a single hip. In general, in an otherwise healthy patient with acute pain in one hip, dedicated imaging of the hip in question (excluding the other hip) is preferred in order to achieve high-resolution images (Fig. While it is possible to change the coil at any point during an examination, this adjustment costs valuable imaging time. Proper coil selection requires that the clinician or radiologist determines prior to imaging whether one or both hips should be included in the FOV. Image quality is highly dependent on proper coil selection. Coil selection depends on many factors, including the manufacturer of the imaging system, patient age and size, shape of the body part imaged, and desired field of view (FOV). Most imaging coils are multichannel, phased-array coils. A variety of imaging coils are useful for imaging the hip.
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