Lumbar plexus MRI is indicated for suspected plexopathy or radiculopathy with unexplained lower‑limb neuropathic pain, weakness or sensory loss; evaluation of masses (neoplasm, metastasis, neurogenic tumors including plexiform neurofibromas); traumatic injury or entrapment; infectious or inflammatory plexus disorders; persistent sciatica with normal spinal imaging; unexplained postoperative or radiation‑related deficits; and preoperative mapping for complex lumbar/pelvic surgery.

A lumbar plexus MRI usually takes about 30–60 minutes. A basic lumbar-spine MRI can be done in 20–45 minutes, while dedicated MR neurography of the lumbosacral plexus or studies requiring contrast and extra sequences may take up to 60–90 minutes. Allow extra time for registration, positioning and any IV contrast preparation.

MRI is a general imaging method that produces detailed pictures of organs, bones, joints and soft tissues. MR neurography is a specialized MRI protocol optimized to visualize peripheral nerves: it uses high-resolution, fat-suppressed and nerve-focused sequences (often diffusion-based) to detect nerve inflammation, entrapment, injury or tumors. In short, MRI shows broad anatomy; MR neurography concentrates on nerve structure and pathology.

Magnetic resonance neurography (MRN) provides high‑resolution imaging of lumbosacral nerve roots and plexus, revealing nerve enlargement, signal changes, inflammation, compression, or structural lesions. Correlating MRN with electrophysiology (EMG/NCS) combines anatomical visualization with functional assessment of conduction and denervation, improving localization, diagnostic accuracy, chronicity assessment, and guiding treatment (medical, surgical, or biopsy), especially when electrodiagnostic results are inconclusive.

The lumbar plexus is a network of nerve fibers formed by the anterior rami of L1–L4 (often with T12) within the psoas major. It provides motor and sensory innervation to the lower abdomen, groin, anterior and medial thigh—via major branches like the femoral and obturator nerves—enabling hip flexion, knee extension, thigh adduction and cutaneous sensation in these regions.

MR neurography visualizes peripheral nerves and their course, showing nerve anatomy, caliber, and signal changes (e.g., T2 hyperintensity) that indicate inflammation, edema, entrapment, compression, trauma, neuroma, or tumor. It detects denervation changes in adjacent muscles, nerve continuity or discontinuity, scarring and fibrosis, and relationships with surrounding soft tissues and masses—helping localize lesions and guide diagnosis or surgical planning.