Temporomandibular Joint, Salivary Gland, and Soft Tissue Imaging
TMJ imaging
Know modalities: panoramic (screening), transcranial, CBCT/CT (bony detail), MRI (gold standard for disc and soft tissue), and arthrography (largely historical). Understand normal anatomy: condyle, glenoid fossa, articular eminence, disc, and bilaminar zone. Recognize internal derangement (anterior disc displacement with/without reduction), osteoarthritis (flattening, osteophytes, sclerosis), and inflammatory arthritis. Know that MRI assesses disc position and joint effusion.
Salivary gland imaging
Modalities: sialography (ductal anatomy), ultrasound (superficial glands, stones), CT (stones, masses), MRI (soft-tissue detail), and nuclear medicine (function, e.g., sialadenitis, Warthin tumor). Recognize sialolithiasis (stone in duct/gland), sialadenitis, and tumors (pleomorphic adenoma vs Warthin). Understand that ultrasound is first-line for superficial gland stones.
Soft tissue imaging
Know the role of ultrasound and MRI for soft-tissue masses, and the appearance of common lesions (lipoma, hemangioma, lymph nodes). Recognize that plain films have limited soft-tissue contrast.
Traps
Questions test which modality is best for a given structure (MRI for disc, ultrasound for stones) and whether a finding is normal vs pathologic. Watch for confusion between disc displacement with vs without reduction.
Rule of thumb
Bone → CBCT/CT; disc and soft tissue → MRI; superficial gland stones → ultrasound; function → nuclear medicine.