xRead - Nasal Obstruction (September 2024) Full Articles

20426984, 0, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/alr.23262, Wiley Online Library on [02/01/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License

69

ICAR SINONASAL TUMORS

over another. In addition, the criteria used to diagnose malignant RPLN on imaging is not clear for sinonasal can cers, nor is it easy to confirm due to inability to verify with pathological diagnosis. Enlarged nodes have previously been noted as having a longitudinal diameter of ≥ 8 mm on CT in maxillary sinus carcinoma or axial diameter of ≥ 5 mm on MRI. 202,205 One study defined its criteria of metastatic RPLNs as ≥ 6 mm diameter, presence of cen tral necrosis, ill-defined margins or extracapsular spread, enhancement, and/or more than two ipsilateral or medial RPLNs. 201 This same study found RPLNs to be associated with worse OS, thus further reinforcing the need to look for RPLNs on initial imaging. 201 B Anatomic imaging Ultrasound of the neck has very limited value in the inves tigation of regional metastasis in sinonasal cancers. A single study discusses its usefulness in identifying cervical lymph nodes in the context of sinonasal tumors extending to the oral cavity and those with aggressive histology, such as SNUC or high-grade ONB. 199,208 With more detailed and improved imaging modalities, CT and MRI have become the mainstay of conventional imaging in sinonasal cancers and are both reported to be accurate and complementary to one another. 198,207,209,210 CT is ideal for assessment of bony landmarks for surgery, bone erosion, and central necrosis of nodal metastasis, while MRI is ideal for locoregional invasion, includ ing intracranial, perineural, and orbital invasion as well as brain metastasis. 198,208,211 In patients with mucosal melanoma, MRI brain is recommended to rule out brain metastasis. 212,213 Criteria for cervical metastasis on CT imaging include size of lymph node ≥ 1.5 cm, nonenhanc ing, irregularity, conglomerate of three or more lymph nodes with poorly defined contour, obliteration of soft tis sue planes, and/or central necrosis with decreased density on imaging. 207 Compared to MRI, CT is faster to perform, better tolerated by patients, and more readily available even in more resource-constrained settings. 208 However, one must take into consideration the risk of radiation with CT. While MRI does not subject patients to ionizing radia tion, it has its own disadvantages, including longer exam ination time, risk of motion artifact, and contraindication in patients with noncompatible metallic devices. 4 In addition to its use in the head and neck, CT is a useful modality to assess for distant metastasis. CT chest is most commonly used to rule out lung metastasis. 209,210,213–215 One study specified the following criteria to consider requesting a CT chest: at least three cer vical lymph nodes, bilateral lymph nodes, size ≥ 6 cm, or lymph nodes in the lower jugular region. 209 InONB and mucosal melanoma patients, additional imaging with CT

abdomen/pelvis is recommended as metastasis can be seen in this region. 213,214

C Functional imaging Hybrid PET scans include PET/CT and PET/MRI. PET/CT has been the most studied in literature for head and neck malignancies and has been shown to have a higher sensitivity in the assessment of regional and distant metastasis. 196 However, a consensus on the benefit of its use in staging of SNM has yet to be achieved. 200,215,98 In a 2012 study by Lamarre et al., PET/CT for SNM was noted to have specificity of 92% and negative pre dictive value (NPV) of 100% for cervical metastasis and a sensitivity and NPV of 100% for distant metastasis. 197 Similarly, Meerwein et al. found hybrid PET has shown a sensitivity and NPV of 100% for both regional and dis tant metastasis. 198 In addition to its excellent accuracy, the benefits of hybrid PET are numerous as this imaging modality allows for a single exam to identify the primary site, cervical metastasis, and distant metastasis, thus sav ing time, reducing patient distress, and lowering costs. 216 Seventeen studies comment on the usefulness of PET imaging in the context of metastatic staging of sinonasal tumors. 68,197,198,204,206,208–214,217–221 Two additional stud ies recommend its usage when metastasis is clinically suspected. 98,222 Two studies recommend that PET/CT use is tailored to the histopathological diagnosis, notably in aggressive pathologies or when a sinonasal lesion is sus pected to be a metastatic lesion. 68,200 Sinonasal SCC, ONB, SNUC, SNEC, and mucosal melanoma are among histopathological diagnoses that warrant use of PET/CT to workup distant metastasis. 200 Adenocarcinoma, on the other hand, is reported to have lower risk of regional and distant metastasis and therefore the use of PET/CT in this diagnosis requires further contemplation. 200 Although the many benefits of PET/CT apply to over all staging, three studies have noted it is clinically more advantageous in the setting of restaging, particularly for regional disease. 198,216,221 Despite the latter, many stud ies still recommend hybrid PET in the initial staging, as this can verify fluorodeoxyglucose (FDG) avidity and allow for baseline imaging for comparison of future PET/CT in the posttreatment setting and can potentially improve management of disease. 216 However, two articles raised caution to the possibility of false-positive results with PET/CT, for example, in the context of inflammation. 197,204 In addition, one must be cognizant of the fact that PET imaging may not identify tumors < 1 cm in size, brain metastasis due to the high FDG uptake of the brain, and scenarios where tumors may not have a high metabolic rate at baseline. 216 Some examples of possible low baseline uptake include ONB, malignant