The role of diffusion-weighted magnetic resonance imaging (MRI) for differentiation between various causes of cervical lymphadenopathy was evaluated. In a prospective study, 31 untreated patients (22 males and nine females, aged 5–70 years) with 87 cervical lymph nodes underwent diffusion-weighted MRI before performance of neck dissection (n=14), surgical biopsy (n=9) or core biopsy (n=8). Diffusion-weighted MR images were acquired with a b factor of 0 and 1,000 s/mm² using single-shot echo-planar sequence. Apparent diffusion coefficient (ADC) maps were reconstructed for all patients. The signal intensity of the lymph nodes was assessed on images obtained at b=0 or 1,000 s/mm² and from the ADC maps. The ADC value of lymph nodes was also calculated. On the ADC map, malignant nodes showed either low (n=52) or mixed (n=20) signal intensity and benign nodes revealed high (n=13) or low (n=2) signal intensity. The mean ADC value of metastatic (1.09±0.11×10⁻³ mm²/s) and lymphomatous (0.97±0.27×10⁻³ mm²/s) lymph nodes was significantly lower than that of benign (1.64±0.16×10⁻³ mm²/s) cervical lymph nodes (P<0.04). When an ADC value of 1.38×10⁻³ mm²/s was used as a threshold value for differentiating malignant from benign lymph nodes, the best results were obtained with an accuracy of 96%, sensitivity of 98%, specificity of 88%, positive predictive value of 98.5% and negative predictive value of 83.7%. The smallest detected lymph node was 0.9 cm. In conclusion, diffusion-weighted MRI with ADC mapping is a new promising technique that can differentiate malignant from benign lymph nodes and delineate the solid viable part of the lymph node for biopsy. This technique provides additional useful physiological and functional information regarding characterization of cervical lymph nodes.

Cerebral vasculitis is characterized by inflammation of the walls of blood vessels and may affect vessels of any size. The pathogenesis of vasculitis remains poorly understood. Vasculitis may affect large vessels (Takayasu arteritis, giant cell arteritis), medium-sized vessels (Kawasaki disease, polyarteritis nodosa), small vessels (immunoglobulin A vasculitis, microscopic polyangiitis, granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis), or variable-sized vessels (Behçet disease, Cogan syndrome). Primary angiitis of the central nervous system (CNS) is an idiopathic disorder with no evidence of generalized inflammation that may simulate reversible cerebral vasoconstriction syndromes. Vasculitis may be secondary to systemic disease, infection, malignancy, drug use, or radiation therapy. Imaging findings vary from small ischemic changes to frank infarction, hemorrhage, and white matter edema and may show contrast material enhancement. The cerebral arteries may demonstrate a beaded appearance with variable degrees of stenosis, occlusion, and contrast enhancement of the vessel wall. Correlation of imaging findings with clinical presentation and laboratory test results helps establish the diagnosis of CNS vasculitis.

BACKGROUND AND PURPOSE: The purpose of this work was to evaluate whether diffusion-weighted MR imaging can be used in differentiating residual or recurrent head and neck tumors from postoperative or postradiation changes.

OBJECTIVE. This article reviews the MRI and CT of nasopharyngeal carcinoma. Extension of nasopharyngeal tumors, especially into the skull base and the deep facial spaces, is well illustrated on imaging. Assessment of retropharyngeal and cervical lymphadenopathy is important for treatment planning. MRI is commonly used for monitoring patients after therapy. CONCLUSION. Imaging can detect effect of radiation on surrounding structures. The imaging findings that help to differentiate nasopharyngeal carcinoma from simulating lesions are discussed.