Musculoskeletal Imaging

Musculoskeletal Imaging

Imaging modalities •ConventionalRadiography •Computed Tomography • Magnetic Resonance Imaging • US •Nuclear Medicine

Imaging modalities ConventionalRadiography Plain films are the most frequently obtained imaging studies for the bones evaluation. Shoulder dislocation

Imaging modalities ConventionalRadiography Some information about the soft tissues are also possible, i.e: gas or calcifications. Gas collection lateral to the hip arthoplasty - infected prosthesis developed abscesses calcified parasital cysts in muscle wound calcifications

Imaging modalities ConventionalRadiography There are standardized sets of views developed for evaluation specific body areas in certain clinical settings, but in the most cases at least two perpendicular views are demanded. PA wrist Lateral wrist

Imaging modalities ConventionalRadiography Many lesions are invisible in one projection, even when they are obvious in another view. A B (A) Anteroposterior and (B) lateral views of a distal fibular fracture. The fracture is displaced only in the sagittal plane.

Imaging modalities ConventionalRadiography For example, if one sees a foreign metal object overlying a body part on a single AP film, the object could actually lie on the skin surface, in the soft tissues of the structure, imbedded in a bone, a visceral organ, or even on the X-ray table. A lateral view can be lots of help in deciding among these many possibilities. This construction worker was using an explosive nail gun while driving nails into concrete. With this film alone, the nail could have been almost anywhere in his knee. The lateral view shows us that the nail resided anteriorly, in the patellar tendon.

Imaging modalities ConventionalRadiography Another case is when one is interested in looking at joint alignment. For example, a posterior dislocation of the shoulder can be a hard diagnosis to make on a single frontal view. An axillary view (taken parallel to the patient’s long axis) usually shows these dislocations easily. An axillary view shows that the humeral head is actually dislocated posteriorly with respect to the glenoid fossa. This patient suffered a gran mal seizure. Sometime later, once he had recovered from the seizure, he complained of right shoulder pain, and this radiograph was taken, showing a shoulder joint that appears to be in anatomic alignment.

Imaging modalities ConventionalRadiography If fracture fragments are only minimally displaced, spotting the fracture can be a challenge. The reason for this is that fractures don’t show up well unless the X-ray beam is parallel to the fracture plane. Since fractures don’t always align themselves in convenient planes that parallel the X-ray beam, it can often be challenging to spot them. This patient fell on her outstretched hand, and now complains of snuffbox tenderness. However, this AP view of the wrist is normal. No fracture line is visualized in the scaphoid. A special scaphoid view clearly shows a fracture across the waist of the scaphoid (arrow).

Imaging modalities ConventionalRadiography Different stress views - are primarily useful in looking at joints and spine stability. This flexion view of the lateral cervical spine shows that the predental space has increased to about 7 mm in size -- which is grossly abnormal. The normal upper limit for this distance is about 3 mm. Since this one is way above that upper limit, we know that the transverse ligament that usually keeps the C1 and C2 vertebral bodies in alignment with each other has ruptured - a known complication of rheumatoid arthritis. This patient with rheumatoid arthritis is complaining of paresthesias with neck flexion. This extension film shows less than a millimeter between the anterior margin of the dens and the anterior arch of C1.

Imaging modalities ConventionalRadiography Some examples of views in radiography of bones and joints. Skull Facial AP Lateral Waters view AP Cervical spine Shoulder AP external rotation AP internal rotation Axillary AP Lateral Knee Elbow AP Lateral Tunnel view AP Lateral

Imaging modalities ConventionalRadiography The importance of different time pictures - comparing an imaging study to a prior examination. This young patient fell on his outstretched hand, and now complains of wrist pain. This AP view shows subtle cortical discontinuities on both sides of the radius (arrows), indicative of a torus fracture. This wrist view was performed on the same patient about 4 - 6 weeks later, and now shows a subtle band of increased opacity across the radius at the site of the prior torus fracture (arrows), consistent with interval callus formation - a healing fracture.

Imaging modalities ConventionalRadiography Normal radiographic and CT apperance of the bone - smooth, homogeneous cortexsurrounds the medullary space. High resolution CT The cortexis thicker along the shaft (diaphysis) of long bones and thinner within their ends or in the small, irregular bones.

Imaging modalities ConventionalRadiography Exceptions from that pattern are: -roughening of the cortex at tendon or ligament insertion sites, and -interruption of the cortexat the site of the nutrient arteries.

Imaging modalities ConventionalRadiography Five types of bones: a Long – 2 ends and a shaft (femur, humerus, phalanges) b Short – Six sided (carpals and tarsals) c Flat – (ribs, sternum) d Irregular – Many sides (vertebrae) e Sesamoid – Lack periosteum and develop in tendons (The largest sesamoid is PATELLA)

Imaging modalities ConventionalRadiography • Bone regions: • – Epiphysis – bony ends • – Physis – Growth plate • – Metaphysis – Widened end of a tubular bone • – Diaphysis – Shaft of a tubular bone • • Proximal third • • Middle third • • Distal third

Imaging modalities ConventionalRadiography In the medullary space there are trabeculaewitch are visible as thin white lines.

Imaging modalities ConventionalRadiography Because of the many anatomical variations the comparison with the opposite extremity is helpful, especially in children, considering the open physes and epiphysesor accesory centers of ossiification, which can mimic injury. Unilateral bipartite hallux epiphysis. If there is a history of trauma to this area, monthly radiographs over several months may be necessary to determine whether or not it is a fracture or variation of normal. accesory center of ossiification open epiphysis

Imaging modalities ConventionalRadiography Some other examples of normal variants. Bone scintigraphy may be a valuable diagnostic study for differentiation between unilateral os trigonum and patology. Focal intense uptake suggests degenerative disease and/or unhealed fracture. Accessory sesamoids - best seen in the axial view.

Imaging modalities ConventionalRadiography Fluoroscopy -it supports positioning patients for unusual radiographic projection, -used to monitor placement of hardware i.e. by orthopedic, -evaluation of joint motion. Postoperative fluoroscopic control of bone fixation with plate and screws after a complete fracture of the humerus.

Imaging modalities ConventionalRadiography A simple way to approach the MS radiograph is to follow the ABC's: A - Anatomy/Alignment: Note the anatomy of the bones. Are they normal in size and relation to other bones articulating with them. Note the contour of the bones and joint surfaces.

Imaging modalities ConventionalRadiography ABC's: B- Bone Density: Observe the bone for any changes in density. Normal is uniform in color or milkiness. Abnormal density is representative of the degree of mineralization. Main conditions increasing density are: healing fractures or degenerative joint disease. Decreased bone density is mostly seen in osteoporosis or neoplastic conditions.

Imaging modalities ConventionalRadiography ABC's: C– Cartilage (joint space): Examine the spaces for uniformity in contour and size. In children the epiphyseal plates are cartilaginous and can be mistaken for fracture lines. Obtain comparative films of the normal side.

Imaging modalities ConventionalRadiography ABC's: `s– Soft tissue: Soft tissue does not distinctly illuminate well on X-Rays. Tissue lines should be examined beginning from the periosteum to the skin lines. Inflammation or swelling in soft tissues may be seen by displacement of the surrounding fat pads.

Imaging modalities ConventionalRadiography Cartilage Articular cartilage is what separates the bones in a synovial joint. This space taken up by the cartilage is termed the "joint space" on a plain radiograph. When considering the joint space, one generally only sees one of the following three findings: -decreased joint space, -increased joint space, -chondrocalcinosis. The most common of these is decreased joint space, which usually implies some form of arthritis. A widened joint space can be seen in patients with acromegaly or in patients with a large joint effusion. Chondrocalcinosis has been reported in an number of entities, but over 95 % of them will be due to calcium pyrophosphate deposition (CPPD) disease.

Imaging modalities ConventionalRadiography Cartilage Chondrocalcinosis (arrows) is noted in the hyaline articular cartilage and menisci of this patient with calcium pyrophosphate deposition (CPPD) disease. Marked joint space narrowing is noted in the superior weight-bearing portion of the joint space in this patient with osteoarthritis.

Imaging modalities Computed Tomography • It offers two major uses in musculoskeletal imaging: • More precise than plain film evaluation of bone structure, which mostly • supports injury diagnosis - fractured fragment position. • 2. Evaluation of bone tumors. Fractured left orbita. Lipoma (F) of the femur.

Imaging modalities Computed Tomography It also offers quite good depicting of soft tissues.

Imaging modalities Computed Tomography Fracture evaluation - axial or frontal images CT usually provides excellent delineation of fractures. Axial scan. Broken fragment of cervical vertebra. Frontal scan. "Blow in" type fracture of the left orbit. Small bone fragment is in the left orbita.

Imaging modalities Computed Tomography Fracture evaluation - MPR images Postprocessing MultiPlanar Reformations allow to see fracure in planes perpendicular, oblique or even curved to primary section.

Imaging modalities Computed Tomography Fracture evaluation - 3D images Three-dimensional reconstructions are not a routine protocol, because they are time-consuming and they do not contain any extra information beyond the source axial scans, but they can: -help to understand spatial relationships of the examined structures, -support the surgeon to plan operative intervention. Multifractured injuries of the thoracic vertebra and the face.

Imaging modalities Computed Tomography Fracture evaluation The decision to use advanced CT imaging beyond conventional films should be based on whether it change treatment or operative planning. Injury of the left orbita in the conventional and CT images: the inferior rectus muscle is stacked in the fissure, which explains the lack of downward movement of the eye.

Imaging modalities Computed Tomography Evaluation of bone tumors CT can show early periosteal new bone formation before it may be seen with conventional radiography or MRI and supports biopsy. Sarcoma of the tibia (circle) and infiltration of adjacent soft tissues (arrows). Biopsy of vertebral body tumor.

Imaging modalities Magnetic Resonance Imaging • The excellent contrast resolution of soft tissues makes it ideal for: • Diagnosis of injuries to muscles, tendons or ligaments about joints. • 2. Evaluating disorders of bone marrow, such as neoplasm, osteomyelitis, metabolic diseaes, avascular necrosis and even fractures. Degenerative disease of left hip with loss of joint space and damage to cartilage. Tear of the left rotator tendon – high signal (arrow).

Imaging modalities Magnetic Resonance Imaging Normal MRI apperance of the bone - smooth, with no signal (black) cortexsurrounds the medullary space. There is lack of trabeculae depiction, but we can recognize the picture of „Bone Bruise” - trabecular microfractures with blood and edema.

Imaging modalities Magnetic Resonance Imaging Evaluation of soft tissues. MRI dynamic studies depict phases of the movement. Liposarcoma of the left thigh (m).

Imaging modalities Magnetic Resonance Imaging Evaluation of bone marrow. MR imaging is more often than CT used for staging, for its clear delineation of tumor extent within bone marrow and muscle or other soft tissues, altough it is non-specific. Osteomyelitis of the right femur – the lack of the normal high signal of marrow. Lymphoma of the left femur – the same pattern of abnormal marrow signal.

Imaging modalities Ultrasonography US may be quick and inexpensive technique to confirm or exclude possible diagnoses from the clinical physical exam. This may then determine the need for other investigations such as MRI, or invasive procedures such as arthrography or biopsy.

Imaging modalities Ultrasonography The applications of US in the evaluation of musculoskeletal disorders include muscle and tendon disease, soft tissue masses, identification of foreign bodies, certain joint abnormalities, and infectious processes such as osteomyelitis and subcutaneous abscesses. Evaluation of tendons. Left Achilles tendon (arrows):tendinitis - hypoechoic and thickened part with loss of the normal fibrillar pattern above the posterior aspect of the calcaneus (arrowhead). Contralateral normal Achilles tendon (arrows) with a fine fibrillar texture; calcaneus pointed by arrowhead.

Imaging modalities Ultrasonography Evaluation of tendons.

Imaging modalities Ultrasonography Evaluation of muscles and soft tissues. gastrocnemius (G) tear with hematoma (arrow)

Imaging modalities Ultrasonography Dynamic studies Ruptured rectus femoris muscle (arrows). A - relaxed and B - retractedfollowing contraction indicating a complete tear. Surface of the femur (arrowheads). A B

Imaging modalities Nuclear Medicine Several types of scintigraphic studies are used for musculoskeletal diseases, mostly more sensitive than X-rays or CT, but non-specific - most osseous abnormalities will cause an increase in radiolabeling. They are often used for screeening for metastases. Bone scintigraphy scan in Paget's disease. Multiple bone metastases.

Imaging modalities Technique Selection The plain radiograph is usually the initial imaging test, followed by the others regarding not only medical need, but also availability and expense. Trauma radiograph visible fracture unvisible strongly suspected fracture location of fragments is desirable nuclear medicine next radiograph in 7 days MRI CT

Imaging modalities Technique Selection Tumors radiograph as screening visible lesion unvisible lesion MRI for local staging MRI as screening CT for precise bone structure inspection

Imaging modalities Technique Selection Metastases Suspected soft-tissue metastases Symptomatic bone sites Overall survey for metastases MRI radiographs scintigraphic studies CT for precise bone structure inspection

Imaging modalities Technique Selection Osteomyelitis radiographs normal pathological MRI scintigraphic studies

Musculoskeletal Imaging