CUHK MR imaging grading systems for detection of NPC using a modified system with a contrast-enhanced scana and a plain scan system with a noncontrast-enhanced scanb
| MR Imaging Gradec | Walls | Adenoid |
|---|---|---|
| Grade 1: normal | Contrast-enhanced/plain scan: thin wall, 1–3 mm | Contrast-enhanced/plain scan: absent/vestigial tags/nubbin |
| Grade 2: probably benign hyperplasia | Contrast-enhanced/plain scan: diffuse thickening (>3 mm), symmetricd size, signal intensity, and contour | Contrast-enhanced scan: composed of Thornwaldt cyst/multiple cysts, OR symmetricd size, signal intensity, and contour with preserved symmetric contrast-enhancing septa perpendicular to the roof, separated by less enhancing columns (ie, stripped appearance) |
| Plain scan: composed of Thornwaldt cyst/multiple cysts | ||
| Grade 3: indeterminate | Contrast-enhanced/plain scan: diffuse thickening (>3 mm); asymmetric size or signal intensity or contour, which is nonexpansile | Contrast-enhanced scan: asymmetric size, signal intensity, OR contour with preserved or partial disruption/internal distortion of contrast-enhancing septa |
| Plain scan: symmetricd size, signal intensity, and contour | ||
| Grade 4: suspicious for NPC | Contrast-enhanced/plain scan: diffuse thickening (>3 mm); asymmetric size or signal intensity or contour, which is expansile (superficial or deep margins) | Contrast-enhanced scan: absent contrast-enhancing septa in a focal adenoid, OR external distortion of contrast-enhancing septa by an adjacent roof mass |
| Plain scan: asymmetric size, signal intensity, or contour | ||
| Grade 5: probably NPC | ||
| 5a | Contrast-enhanced/plain scan: focal mass | Contrast-enhanced scan: absent contrast-enhancing septa in an adenoid filling the whole roof on at least 1 section |
| Plain scan: no grade | ||
| 5b | Contrast-enhanced/plain scan: spread outside the nasopharynx (superficial or deep) | |
| 5c | Contrast-enhanced/plain scan: metastatic retropharyngeal or upper cervical nodese | |
Note: —CUHK indicates Chinese University of Hong Kong; NPC, nasopharyngeal carcinoma.
↵a Modified MR imaging protocol: T2- and T1-weighted images without and with intravenous contrast enhancement.
↵b Plain scan MR imaging protocol: T2- and T1-weighted images without intravenous contrast enhancement.
↵c For the modified grading system, the grade for contrast-enhanced images outranks the grade for non-contrast-enhanced images.
↵d Symmetry refers to a comparison of the right and left halves of the nasopharynx for size, signal intensity, and contour; cysts do not contribute to wall or adenoid asymmetry or to distortion of adenoidal septa.
↵e Diagnosis of a metastatic node is based on size (minimum axial nodal diameter: retropharyngeal, ≥6 mm; jugulodigastric, ≥11 mm; all other nodes, ≥10 mm or groups of ≥3 nodes with a minimal axial diameter of ≥8 mm) or any node with necrosis or extracapsular spread.