Category Archives: Principles of Assessment and Evaluation

Spinal Trauma

Although much spinal trauma is well visualized on plain films, CT has a number of advantages over this modality. These include the demonstration of fractures not seen in plain films, an accurate determination of the amount of spinal canal encroachment by fracture fragments (Fig. 6-66A,B), the identification of neural foramen impingement by fractures involving its […]

Other Ankle Abnormalities

Technetium-99 scintigraphy has been valuable for detecting stress fractures of metatarsal and tarsal bones, and CT has high accuracy for detecting osteochondral fracture. In foot pain of undetermined etiology, however, MRI is an excellent screening modality because it permits direct evaluation of all osseous and soft-tissue structures. MRI is superior to any other modality in […]

Complications of Brain Injury

Brain injuries may be accompanied by a number of late or long-term complications. These secondary brain injuries include cerebral herniations, which may occur under the falx cerebri or through the tentorium. Herniations can cause compression of adjacent brain substance or vessels, with the production of secondary signs and symptoms (Fig. 6-93). Penetrating injuries or fractures […]

Ankle Ligament Imaging

Previously, arthrography and tenography were the primary means of imaging ankle ligament injuries. They had the limitations of being invasive, providing only an indirect depiction of ankle ligament disruption, and yielding potentially false- negative results. MRI provides a noninvasive means of directly imaging all the ligaments in the vicinity of the ankle as well as […]

Diffuse Brain Injuries

Diffuse brain injuries include diffuse axonal injury, diffuse cerebral swelling, and edema. Diffuse axonal injury is produced by high shearing stresses that occur at different parts of the brain, including at the gray matter-white matter interface. These shearing stresses cause axonal stretching commonly involving the corpus callosum, anterior commissure, and upper brain stem. Blood vessels […]

Spondylolysis and Spondylolisthesis

Spondylolysis is a defect in the pars interarticularis, commonly involving the L5 and occasionally the L4 vertebrae. Most spondylolysis is thought to be produced by repetitive stress. The gravitational and muscular loads acting across the steep incline of the upper surface of the sacrum can be resolved into a shearing component, which tends to displace […]

Lumbar Spinal Stenosis and Foraminal Stenosis

Like cervical stenosis, lumbar spinal stenosis is frequently precipitated by disc degeneration with subsequent marginal osteophytosis of the vertebral body ends, hypertrophic degeneration of the facet joints, and bulging of the ligamenta flava. Lumbar stenosis may be lateral, central, or combined. The lower lumbar vertebrae normally have shorter pedicles that cause the superior articular processes […]

Contusions and Intraparenchymal Hemorrhage

Focal parenchymal injuries such as contusions and intraparenchymal hemorrhage usually develop as a result of contact of the brain with the osseous walls of the cranial cavity. The coup-type injuries occur at the point of contact, and the contrecoup injuries occur on the opposite side of the brain. Contusions often occur in areas where the […]

Other Knee Abnormalities

Patellar tendinitis (jumper’s knee) is demonstrated by MRI as an area of edema within the patellar ligament (i.e., tendon) at its patellar (Fig. 6-28) or tibial tuberosity attachment. There is also associated edema in the adjacent subcutaneous fat or the infrapatellar fat pad. FIGURE 6-28. Sagittal T2-weighted fat suppressed image of patellar tendinitis. The arrow […]

Subdural Hematoma

Subdural hematoma is most commonly caused by acceleration- deceleration shearing stresses that rupture the bridging veins that extend from the movable brain to the fixed dural venous sinuses. The blood accumulates in a pre-existing but essentially volumeless subdural space. Normally, the pressure of the CSF holds the arachnoid in contact with the dura, thereby creating […]