Article Figures & Data
Tables
- Table 1:
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.
- Table 2:
Patients with and without NPC in each MR imaging grade as determined using the current, modified, and plain scan MR imaging grading systems
Grading Systems No. of Patients without NPC No. of Patients with NPC Nodes Not Assessed Nodes Assessed Nodes Not Assessed Nodes Assessed Grade 1 Current 69 – 0 – Modified 69 69 0 0 Plain scan 79 78 0 0 Grade 2 Current 174 – 1 – Modified 174 170 1 1 Plain scan 147 146 2 1 Grade 3 Current 132 – 47 – Modified 109 104 13 7 Plain scan 112 107 15 8 Grade 4 Current 8 – 335 – Modified 28 26 91 26 Plain scan 42 38 123 32 Grade 5 Current – – – – Modified 3 14 278 349 Plain scan 3 14 243 342 Note:—– indicates not applicable; NPC, nasopharyngeal carcinoma.
- Table 3:
Diagnostic performance of MR imaging after grouping of grades into benign or malignant according to grades in the current, modified, and plain scan grading systems
MR Imaging Grade Grouping to Indicate NPC FP FN TP TN Sen % Spec % PPV % NPV % Accuracy % Grades in the current system Primary tumor 3, 4a 140 1 382 243 99.74 63.45 73.18 99.59 81.59 Primary tumor only 4 8 48 335 375 87.47 97.91 97.67 88.65 92.69 Grades in the modified system Primary tumor 3, 4, 5 140 1 382 243 99.74 63.45 73.18 99.59 81.59 Primary tumor 4, 5 31 14 369 352 96.34 91.91 92.25 96.17 94.13 Primary tumor 4, 5 + node 5a 40 8 375 343 97.91 89.56 90.36 97.72 93.73 Grades in the plain scan system Primary tumor 4, 5 45 17 366 338 95.56 88.25 89.05 95.21 91.91 Primary tumor 4, 5 + node 5a 52 9 374 331 97.65 86.42 87.79 97.35 92.04 Note:—FP indicates false-positive; FN, false-negative; TP, true-positive; TN, true-negative; Sen, sensitivity; Spec, specificity; PPV, positive predictive value; NPV, negative predictive value.
↵a Combination of grades in the respective current, modified, and plain scan systems in Table 2.
- Table 4:
Differences in the diagnostic performances of the current, modified, and plain scan grading systems
Grading Systems to Indicate NPC Sens Spec Combined Sens and Spec Youden Index 
(Significance, >3.84)(Significance, >5.99)Current system, primary tumor (3, 4)a vs Modified system using only primary tumor (4, 5)b 13a 109b 122b a = 72.8%; b = 88.4% Current system, primary tumor (3, 4)a vs modified system, primary tumor (4, 5) + node (5)c 7a 21.3c 28.3c a = 72.8%; c = 88.1% Modified system using only primary tumor (4, 5)d vs modified system, primary tumor (4, 5) + node (5)c 6c 9d 15d c = 88.4%; d = 88.1% Modified system, primary tumor (4, 5) + node (5)c vs plain scan system, primary tumor (4, 5) + node (5)e 1 5.14c 6.14c c = 88.1%; e = 85.2% Note:—Superscript refers to the grading system with the best performance; NPC indicates nasopharyngeal carcinoma; sens, sensitivity; spec, specificity.
↵a Current system, primary tumor (3, 4).
↵b Modified system using only primary tumor (4, 5).
↵c Modified system, primary tumor (4, 5) + node (5).
↵d Modified system using only primary tumor (4, 5).
↵e Plain-scan system, primary tumor (4, 5) + node (5).
