ABSTRACT
Cases of certain pathological conditions demand advanced evaluation or imaging. If a patient presents with a palpable mass, for example, it is essential to establish whether it is an enlarged LN. Magnetic resonance imaging (MRI) serves as a significant tool for the evaluation of diseases related to the neck. Like computed tomography (CT), MRI has the advantage of crosssectional imaging. In addition, multiplanar MRI capability allows for the simple differentiation of LNs, masses, vessels, and other soft tissue components [4]. However, MRI is superior to CT in that its contrast resolution for soft tissues is high and it does not necessitate iodinated contrast material administration. Thus, another advantage of MRI is that the patient is not exposed to ionizing radiation, which is especially important for patients who may need multiple or follow-up scans. Another advantage of MRI is the protection of the thyroid gland from radiation, especially during childhood. However,
Fatih Alper, Irmak Durur-Subasi, and Adem Karaman
CONTENTS
18.1 Introduction ................................................................................................................................................................. 453 18.2 Normal Nodal Anatomy of the Neck ....................................................................................................................... 454
18.2.1 Benign LNs ..................................................................................................................................................... 454 18.2.2 LN Levels ........................................................................................................................................................ 455
18.3 Pathologic LNs............................................................................................................................................................. 456 18.3.1 Size and Shape ............................................................................................................................................... 458 18.3.2 Central Necrosis ............................................................................................................................................ 460 18.3.3 Extracapsular Spread .................................................................................................................................... 462 18.3.4 Carotid Artery Invasion ............................................................................................................................... 464
18.4 Magnetic Resonance Imaging ................................................................................................................................... 467 18.4.1 Examination Technique ................................................................................................................................ 467 18.4.2 Conventional MRI Sequences ...................................................................................................................... 469 18.4.3 Short-Tau Inversion Recovery ..................................................................................................................... 469 18.4.4 Dynamic Contrast-Enhanced MRI .............................................................................................................. 469 18.4.5 Diffusion-Weighted Imaging ....................................................................................................................... 469 18.4.6 USPIO-Enhanced MRI .................................................................................................................................. 470 18.4.7 Gadofluorine M-Enhanced MRI .................................................................................................................. 470 18.4.8 Proton Magnetic Resonance Spectroscopy ................................................................................................ 471
18.5 Diagnostic Issues ......................................................................................................................................................... 471 References ................................................................................................................................................................................ 479
one drawback is that smaller children often cannot cooperate by keeping still for the duration of the scan, and general anesthesia or sedation may be necessary to prevent motion artifacts [4].
