CRISPS: A Pictorial Essay of an Acronym to Interpreting Metastatic Head and Neck Lymphadenopathy

Lymph node metastasis in head and neck cancer isa significant prognostic indicator that has a major impactboth on treatment planning and patient survival [1]. Becauseaggressive treatment for primary malignancy has becomemore advanced, patients often live long enough to experienceeither recurrence or distant metastasis. Nodal disease and,particularly, its presence on first presentation is the mostreliable predictor for both of these phenomena [2e5]. Withregard to the natural history of this head and neck cancer, themost common sites of metastasis from positive cervicallymph nodes are the lungs, bones, and liver [6].The rate of metastasis varies among different areas of theaerodigestive tract. For instance, T3/T4 carcinomas of theoral cavity, oropharynx, hypopharynx, and supraglotticlarynx exhibit ipsilateral nodal metastasis at a rate of higherthan 50% [7]. The rate of either bilateral or contralateralnodal metastasis ranges from 2%-35% [8,9]. Radiologicidentification of nodal disease thus is critical to guidesurgical decision making regarding neck dissection becauseimaging has been shown to identify metastasis in 7.5%-19%of clinically silent nodes [2,3,9].The identification of nodal disease is important withregard to both the pre- and posttreatment stages. Pretreat-ment imaging has been shown to identify areas of involve-ment in the retropharyngeal, high level II, low level IV, lowlevel V, and level VI/VII nodes [7]. As a result, pretreatmentcomputed tomography (CT) or magnetic resonance imaging(MRI) has become a mainstay of the care plan for patientswith head and neck cancer. The wide acceptance of theradiologic definition of nodal levels has expedited thistransition. Diseased lymph nodes are identified radiologi-cally by their clustering, roundness (shape), inhomogeneity,size, and periphery (extracapsular spread). In addition,the radiologist should be familiar with the most probablesentinel nodes for a given malignancy. For this reason, wepropose the acronym ‘‘CRISPS’’ (clustering, rounded shape,inhomogeneity, size, periphery, sentinel location) asa comprehensive and easy-to-remember mnemonic to aid theradiologist in identifying nodal involvement in patients withhead and neck cancer.Contrast-enhanced CT represents the ideal modalityfor the assessment of metastatic lymphadenopathy, followedclosely by magnetic resonance (MR) pulse sequences(unenhanced T1 or T2 with fat saturation) [10]. Positronemission tomographyeCT possesses the advantage ofmetabolic correlation, which can aid both in the setting ofequivocal findings and distant disease. However, challenges