Temporomandibular joint: morphology and signal intensity characteristics of the disk at MR imaging

Article Abstract:

Magnetic resonance (MR) imaging is a useful technique for documenting internal derangement of the temporomandibular joint (TMJ, the joint of the jaw located in front of the ear). MR imaging reflects the location of the disk in the TMJ as well as the morphology and signal intensity characteristics of the disk. This report considers the alterations in disk morphology and signal intensity with regard to derangement of the TMJ. Researchers obtained MR images of the TMJ in 133 patients (216 joints with a history of derangement) noting the position, morphology, and signal intensity of the disk and the presence or absence of osteoarthritis of the joint (characterized by chronic inflammation, destruction of cartilage, overgrowth of bone and impaired function). The MR images of the TMJ disks were placed in three categories: normal, grade 1 (displaced with a normal shape), and grade 2 (displaced with an abnormal shape). Nineteen percent of the disks were considered normal; none showed osteoarthritis. Sixty-four percent of the disks were reported as grade 1 with 17 percent having osteoarthritis. Grade 2 disks represented only 17 percent of the imaged TMJ disks, but 95 percent of them showed osteoarthritis. TMJ joints with osteoarthritis exhibited diminished signal intensity, and osteoarthritis is a known complication of severe or untreated TMJ derangement. As the TMJ disk degenerates it loses its normal shape and becomes a mass of fibrous tissue. The grading system seems to accurately describe the clinical findings and correlate with the diagnoses. However, further evaluation of MR imaging of TMJ disk deformity is needed before this technique can achieve widespread clinical application.

Joints, Joints (Anatomy), Diagnosis, Osteoarthritis, Stomatognathic system, Jaws, Jaw, Temporomandibular joint

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Bone marrow disorders: characterization with quantitative MR imaging

Article Abstract:

Because bone marrow contains a large portion of mobile protons in fat and water in blood cell producing spongy tissue it is ideally suited for study with magnetic resonance (MR) imaging. Areas of bone marrow abnormality can be detected with MR, but the use of MR to specifically diagnose marrow abnormalities is unknown. Researchers used quantitative MR imaging of the lumbar spine (lower curve) to characterize hematologic (blood) disorders in 30 patients with clinically and biopsy-proven disorders and 15 healthy control subjects. Images of the patients with infiltrative bone marrow disorders showed longer T1 (spin-lattice) times than the control subjects. However, MR imaging did not demonstrate diagnostic capabilities in evaluating diffuse bone marrow infiltrates. The researchers report that quantitative MR imaging of the lumbar spine may be of value in the detection of focal (centralized) marrow abnormalities in lymphomas (abnormal growth in the lymphatic system), such as Hodgkin's disease. Preliminary results of the use of quantitative MR imaging in childhood and adult leukemia patients who are receiving bone marrow suppression therapy have also been encouraging. The role of quantitative MR imaging for following treatment responses in diseases that focally affect marrow has yet to be fully assessed.

Bone marrow, Vertebrae, Lumbar, Lumbar vertebrae

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