How to Image the Knee See the protocols for knee MRI at the end of this chapter. Magnetic resonance imaging (MRI) of the knee is the most frequently requested MRI joint study in musculoskeletal radiology. The reasons for this are simple: it works, and so referring physicians request it. MRI provides a comprehensive examination of the knee, giving surgeons information they could not otherwise obtain clinically…
How to Image the Hips and Pelvis See the hip and pelvis protocols at the end of the chapter. Coils and patient position: Generally, when evaluating the hips for entities such as avascular necrosis (AVN) or fractures, it is possible in many patients to use a torso phased array coil. For larger patients, the body coil is necessary. Both hips and the entire pelvis are imaged…
How to Image the Spine See spine protocols at the end of the chapter. Coils and patient position: Phased array spine coils should be used for all spine imaging. Patients are supine in the magnet. Image orientation ( Box 13.1 ): Sagittal and axial images are acquired in the cervical, thoracic, and lumbar regions. In the axial imaging plane, we obtain stacked cuts that cover an…
How to Image the Wrist and Hand See the wrist and hand protocols at the end of the chapter. Coils and patient position: Some type of surface coil is an absolute requirement for proper wrist imaging. Many different coils may be used depending on the size of the patient’s wrist, including dedicated wrist coils. Generally, the smaller the coil, the better the images. The challenge for…
How to Image the Elbow Coils and patient position: The elbow is typically scanned with the patient in a supine position with the arm at the side and palm up. A surface coil is imperative for obtaining high-quality images. The surface coil of choice depends on the size of the patient’s elbow being studied. The coil selection should allow for an optimum field of view. Occasionally,…
How to Image the Shoulder See the shoulder protocols at the end of the chapter. Coils and patient position: A surface coil is required to obtain high-resolution, detailed images. The patient is positioned supine with the arm at the side in neutral position or slight external rotation for a standard examination. The arm position influences how well anatomic structures can be identified on magnetic resonance (MR)…
How to Image the Temporomandibular Joint See the temporomandibular joint (TMJ) protocols at the end of the chapter. Coils and patient position: Small surface coils are used, generally with a diameter of about 3 inches. Bilateral simultaneous examinations of the TMJs can be done with coupled surface coils. The patient is supine in the bore of the magnet, with the coils centered over the TMJs just…
How to Image Osseous Trauma Coils and patient position: The patient should be placed in a comfortable position with passive restraints, such as tape or Velcro straps, applied to the region of interest to minimize motion. Pain medication also may be required in cases of acute trauma to improve patient comfort. Although the body coil may be used in cases where a large field of view…
Magnetic resonance imaging (MRI) plays a central role in the work-up of a patient presenting with a suspected musculoskeletal tumor. MRI can confirm the presence of a lesion, allow for a specific diagnosis in some cases, define the extent of tumor spread, provide biopsy guidance, and assist in the evaluation of recurrent disease after therapy. Therapeutic planning at the time of presentation is based primarily on…
How to Image Arthritis and Cartilage Magnetic resonance imaging ( MRI ) remains the ideal imaging technique for evaluating articular cartilage, as it allows for direct visualization of the cartilage and subchondral bone, and its multiplanar capability and exquisite soft tissue contrast provide unparalleled information about structures in and around the joint space. Although the diagnosis of the type of arthritis is made with conventional radiographs,…
How to Image Infection ( Box 5.1 ) Musculoskeletal infections affect bones, soft tissues, and joints. Infection is often considered a therapeutic emergency, and magnetic resonance imaging (MRI) is a valuable tool for demonstrating the presence or absence of disease and its extent. The MRI study should be directed to the site of involvement based on clinical grounds or where abnormalities on other imaging studies have…
How to Image Nerves Coils and patient position: High-resolution images of the small peripheral nerves require the use of phased array surface coils. The large sciatic nerve can be evaluated without a surface coil, but better resolution is possible if surface coils are used. Positioning of the patient is determined by which nerve is being evaluated. Generally, the nerve can be imaged with the same surface…
How to Image Tendons Coils and patient position: Whether or not a coil should be used is based entirely on the anatomy to be imaged. Generally, surface coils improve images and should be used. For large areas, such as the thighs or pelvis, this approach is not practical, and surface coils are not used. Patients should be positioned as if the nearest joint were being imaged.…
How to Image Bone Marrow The most useful magnetic resonance imaging (MRI) sequences for evaluating the marrow are T1-weighted (T1W) and fat-suppressed T2-weighted (T2W) (either short tau inversion recovery [STIR] or fast spin echo [FSE] T2 with fat suppression) sequences. For brevity, when used in this chapter, “T2W” will refer to a “fluid-sensitive sequence” such as STIR or FSE with fat suppression. As discussed in the…
Although a detailed understanding of nuclear physics is not necessary to interpret magnetic resonance imaging (MRI) studies, it also is unacceptable to read passively whatever images you are given without concern for how the images are acquired or how they might be improved. Radiologists should have a solid understanding of the basic principles involved in acquiring excellent images. This chapter describes the various components that go…
The chest wall is a complex anatomic structure composed of muscles, bones, joints, and soft tissues that make up the area of the body between the neck and the abdomen. Pathologic processes that may involve the chest wall include congenital and developmental anomalies, trauma, inflammatory and infectious diseases, and soft tissue and bone tumors. Because the clinical presentation of patients with chest wall disorders is diverse…
Abnormalities of Diaphragmatic Motion: Diaphragmatic Paralysis, Weakness, and Eventration Etiology, Prevalence, and Epidemiology The diaphragm is the primary muscle of ventilation, and dysfunction of the diaphragm is an underrecognized cause of dyspnea. Dysfunction of the diaphragm can be classified as paralysis, weakness, or eventration and is usually suggested by elevation of a hemidiaphragm on chest radiography. Some of the more common causes of unilateral diaphragmatic paralysis…
Mediastinal masses are relatively uncommon and include a wide variety of abnormalities of neoplastic, congenital, vascular, and lymphatic etiology that most radiologists encounter infrequently. Imaging plays a critical role in the identification and evaluation of mediastinal lesions, facilitating the formulation of focused differential diagnoses and guiding clinical management. In some cases mediastinal masses demonstrate imaging characteristics that can suggest a specific diagnosis; in other instances the…
Mediastinitis refers to a focal or diffuse inflammation of the tissues located in the mediastinum. The mediastinum lies between the right and left pleural cavities and extends from the thoracic inlet to the diaphragm. Mediastinitis can be classified into acute and chronic forms. Acute mediastinitis is usually a catastrophic disorder manifesting with a sudden and dramatic onset and a high mortality rate when the diagnosis is…
Etiology, Prevalence, and Epidemiology Pneumomediastinum, also known as mediastinal emphysema, refers to the presence of free air or other gas in the mediastinal space. Pathologically, the major sources of entry of air to the mediastinum are (1) through the skin and chest wall, as commonly seen in penetrating trauma; (2) from the neck; (3) from a tear or defect in the esophagus or the trachea, allowing…