Article Figures & Data
Figures
- Fig 1.
A, Axial T1-weighted postcontrast MR image of the nasopharynx in a 51-year-old man with NPC (open arrow). An asymmetric tumor with a lateral center at the level of the left pharyngeal recess is confined to 1 side of the nasopharynx. The tumor exhibits homogeneous low contrast enhancement with an intact deep mucosal white line (small solid arrows) along the deep margin. B, Axial T1-weighted postcontrast MR image of the nasopharynx in a 68-year-old man with NPC (open arrow). An asymmetric tumor with a lateral center at the level of the left pharyngeal recess is confined to 1 side of the nasopharynx. The tumor exhibits homogeneous moderate contrast enhancement with a focal loss of the deep mucosal white line (small solid arrows) along the deep margin. C, Axial T1-weighted postcontrast MR image of the nasopharynx in a 44-year-old woman with NPC (open arrow). An asymmetric tumor with a lateral center at the level of the right side of the roof shows heterogeneous contrast enhancement.
- Fig 2.
Axial T1-weighted postcontrast MR image of the nasopharynx in a 32-year-old woman with NPC (open arrow). An asymmetric tumor with a central center in the adenoid exhibits homogeneous contrast enhancement and loss of the normal adenoidal septa.
- Fig 3.
A, Axial T1-weighted postcontrast MR image of the nasopharynx in a 51-year-old man with NPC (open arrows). A symmetric tumor with diffuse involvement of all nasopharyngeal walls exhibits homogeneous contrast enhancement without a white line along the deep mucosal margin. B, Axial T1-weighted postcontrast MR image of the nasopharynx in a 59-year-old man with NPC (open arrows). A symmetric tumor with diffuse involvement of the nasopharyngeal walls exhibits homogeneous low contrast enhancement and an intact mucosal white line along the deep margin. The adenoid extends along the posterior wall from the roof, with an adenoidal “stripe” on the right (curved open arrow) but not on the left side. A small right retropharyngeal node is also indicated (solid arrow). The patient had bulky N3-stage metastatic nodes below this level.
- Fig 4.
A, Axial T1-weighted postcontrast MR image of the nasopharynx in a 53-year-old man with BH1 (open arrows). An area of diffuse symmetric mucosal thickening with homogeneous contrast enhancement is visible. B, Axial T1-weighted postcontrast MR image of the nasopharynx in a 28-year-old man with BH2 of the adenoid (open arrow). The symmetric lesion exhibits contrast-enhancing septa that run perpendicular to the nasopharyngeal wall and are separated by columns of low contrast enhancement. C, Axial T1-weighted postcontrast MR image of the nasopharynx in a 48-year-old woman with BH2 along the nasopharyngeal walls (open arrows). An area of diffuse, symmetric homogeneous low contrast enhancement and an intact deep mucosal white line along the deep margin are visible.
- Fig 5.
A, Boxplots showing differences in the T1 postcontrast signal intensity ratios (relative to muscle) among NPC, BH1, and BH2. B, Boxplots show differences in the T2 signal intensity ratios (relative to muscle) among NPC, BH1, and BH2.
- Fig 6.
Receiver operating characteristic curve of the percentage difference in area for NPC detection.
- Fig 7.
Axial T1-weighted postcontrast MR image of the nasopharynx in a 52-year-old man with asymmetric BH. Greater thickening is observed in the left side of the roof (open arrows), where a focal area of mucosal thickening comprises a superficial band of low contrast enhancement overlying an intact deep mucosal white line (BH type 2). A Tornwaldt cyst is also present (solid arrow).
Tables
MR Imaging Features of NPC Method of Analysis Site Walls: mucosa plus submucosa, including the lymphoid tissue layers in the mucosal space superficial to the fascia and pharyngeal muscles; wall subsites comprise the following: the pharyngeal recess, roof (above the level of the pharyngeal recess), and posterior/inferior walls (at or below the level of the pharyngeal recess) Adenoid: central mucosal lymphoid tissues in the roof and upper posterior wall where lymphoid tissue within the nasopharynx is abundant Center: lateral, central, or diffuse Size Volume (area of nasopharyngeal walls and adenoid on each slice × slice thickness) Size asymmetry Area difference between the right and left halves of the nasopharynx on the slice with the maximum difference, expressed as the %ΔA (difference in area between the 2 sides/area on smaller side × 100) Signal intensity Representative ROI is selected on the T1-weighted postcontrast image (T2-weighted signal intensity is measured at the corresponding site); signal intensity is expressed as a ratio of signal intensity/signal intensity of the belly of the lateral pterygoid muscle Signal intensity asymmetry Subjective signal intensity asymmetry between the right and left halves of the nasopharynx on T1-weighted postcontrast images Homogeneity Subjective assessment of signal intensity on T1-weighted postcontrast images, divided into homogeneous and heterogeneous Deep mucosal white line Line/band of greater contrast enhancement in the deep layer relative to the superficial layer of the nasopharyngeal wall at the site of the tumor, divided into absent, present with focal loss, and present and intact; assessment was not made at the adenoid Adenoidal septa Contrast-enhancing septa within the adenoid, divided into absent, present and distorted (displacement or partial loss excluding that caused by adenoidal cysts), and present and not distorted (intact and symmetric) Volume Size Asymmetry Signal Asymmetry Deep Mucosal White Line Adenoid Test positive for NPC Volume ≥ 5.01 cm3 %ΔA ≥ 33.7% Signal asymmetry present Focal loss of the deep mucosal white line Septa absent or distorted (excluding septa distorted by cysts) n = 333 (NPC = 189, BH = 144) n = 333 (NPC = 189, BH = 144) n = 333 (NPC = 189, BH = 144) n = 253 (NPC = 180, BH2 = 73) n = 172 (NPC = 111, BH2 = 61) Area under the curve (95% CI) 0.676 (0.618–0.734) 0.948 (0.926–0.971) P value <.001 <.001 True-positive (No.) 119 167 161 153 111 False-positive (No.) 47 13 26 10 9 True-negative (No.) 97 131 118 63 52 False-negative (No.) 70 22 28 27 0 Sensitivity (%) 63.0 88.4 85.2 85.0 100.0 Specificity (%) 67.4 91.0 81.9 86.3 85.2 Positive predictive value (%) 71.7 92.8 86.1 93.9 92.5 Negative predictive value (%) 58.1 85.6 80.8 70.0 100.0 Accuracy (%) 64.9 89.5 83.8 85.4 94.8 Volume Signal Asymmetry Deep Mucosal White Line Adenoid Test positive for NPC Volume ≥ 5.01 cm3 Signal asymmetry present Focal loss of the deep mucosal white line Septa absent or distorted (excluding septa distorted by cysts) n = 153 (NPC = 22, BH = 131) n = 153 (NPC = 22, BH = 131) n = 83 (NPC = 20, BH2 = 63) n = 72 (NPC = 16, BH2 = 56) True-positive (No.) 20 11 16 16 False-positive (No.) 42 15 8 8 True-negative (No.) 89 116 55 48 False-negative (No.) 2 11 4 0 Sensitivity (%) 90.1 50.0 80.0 100.0 Specificity (%) 67.9 88.5 87.3 85.7 Positive predictive value (%) 32.3 42.3 66.7 66.7 Negative predictive value (%) 97.8 91.3 93.2 100 Accuracy (%) 71.2 83.0 85.5 88.9 Grade Condition Appearance 1 Normal Thin mucosa ≤3 mm; adenoid absent, vestigial or composed almost entirely of cysts 2 Probably benign Diffusely thickened >3-mm symmetric mucosa either homogeneously enhancing (benign hyperplasia type 1) or with greater contrast enhancement in the deep layer (mucosal white line) compared with the superficial layer (benign hyperplasia type 2); adenoid with intact contrast-enhancing septa (benign hyperplasia type 2) 3 Indeterminate Diffusely thickened >3-mm mucosa asymmetric in thickness; adenoid asymmetric in thickness 4 Suspicious 1) Diffusely thickened >3-mm mucosa asymmetric in signal intensity; adenoid asymmetric in signal intensity 2) Diffusely thickened mucosa >3 mm with focal loss of the mucosal white line; absence/distortion of the thin contrast-enhancing adenoidal septa (not attributed to cysts) 3) Focal mass confined within the nasopharynx 5 Probably malignant Superficial extension to the nasal cavity/oropharynx or deep extension to the sites bordering the nasopharynx
