Cervical lymphadenopathy is a common clinical entity with varied causes ranging from benign to malignant. Amongst benign causes, tuberculous lymphadenopathy is the most common etiology in endemic areas.1 Its incidence also increasing in developed countries with the increasing prevalence of acquired immunodeficiency syndrome (AIDS). Tuberculous lymphadenitis is the most common form of extrapulmonary tuberculosis.2 It is frequently bilateral with predilection for the posterior triangle of the neck. The involvement of lower cervical group of lymph nodes concomitantly increases the incidence of pulmonary involvement.3 There are three patterns of lymph node involvement. Imaging findings depends upon the stage of the disease at the time of examination. In the acute stage of tubercular granuloma, the lymph nodes are enlarged with homogeneous appearance. As the diseases progresses, the second pattern or the most common pattern of a suppurative node with central necrosis is seen. The third pattern is of a fibrocalcified node, frequently seen in chronic phase or treated patients.3,4,5 Proper diagnosis is required before initiating treatment due to prolonged and cumbersome drug regime. Radiological evaluation is performed in patients lacking the typical associated clinical features, nodes not amenable to clinical examination and patients not responding to treatment.
FNAC/ biopsy remains the gold standard for final diagnosis of cervical lymphadenopathy. On histopathological examinatione majority of these nodes turn out to be benign, as malignancy accounts for less 1% of all cases of lymphadenopathy,6 hence an effective non-invasive imaging assessment can help preclude the need for invasive diagnostic procedures for obtaining a definite diagnosis.
Imaging modalities available for assessment of lymph nodes are Ultrasound (US), including color Doppler and sonoelastography, Computed Tomography(CT) and Magnetic Resonance Imaging(MRI).
Ultrasound is commonly used for evaluation of cervical lymphadenopathy as the nodes are superficial, easily accessible, non-invasive and free from risk of radiation. On US, a node is assessed for its location, size, shape, echogenecity, presence of intranodal necrosis, calcification and ancillary features, such as, matting and soft tissue edema. On Color Doppler, the pattern of vascularity was assessed.
CT and MRI helps to further characterize the sonographic abnormalities, confirm lymph nodes situated in deeper locations, with superior anatomical localization. However CT is associated with risk of radiation and MR studies are time consuming and require sedation in pediatric population.7
Ultrasound elastography (USE) has principle similar to the clinical method palpation and is a more objective method of assessment. The principle underlying strain elastography is that tissue compression produces a strain (displacement). This strain is seen to be lower in stiff tissues than in the softer tissues.8 Strain elastography is a very promising imaging modality for characterization of lymph nodes, especially the cervical lymph nodes which are easily accessible and effective compression can be applied using the transducer, against the underlying structures to obtain the color coded elastogram and strain ratio.
The current study aims to assess the utility of strain elastography in tuberculous nodes, which account for significant proportion of benign cervical lymphadenopathy.