MRI Posttreatment Surveillance for Head and Neck Squamous Cell Carcinoma: Proposed MR NI-RADS Criteria

M.M. Ashour; E.A.F. Darwish; R.M. Fahiem; T.T. Abdelaziz

doi:10.3174/ajnr.A7058

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FIG 1.
Concordance between NI-RADS category, T2 SI, and DWIs is demonstrated in this posttreatment MR imaging surveillance scan done after surgery and RTH for sinonasal squamous cell carcinoma. Coronal T2WI (A) and coronal contrast-enhanced T1WI (B) show a surgical bed discrete nodule (black arrow) that displays intermediate T2 SI (A) and postcontrast enhancement (B), fulfilling NI-RADS 3 and confirmed to be squamous cell carcinoma by histopathology. C. Axial ADC map of the surgical bed shows a corresponding low-ADC signal (black arrow). White arrows point to circumferential soft tissue thickening with sheetlike enhancement (B), which shows low T2 SI (A), absent diffusion restriction (D), and was confirmed to be posttreatment fibrous tissue.
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FIG 2.
The first post-CRTH MR imaging follow-up for a known case of nasopharyngeal carcinoma with perineural tumor spread (PNTS) showing discordant findings between NI-RADS category, T2 SI, and DWI. There is a clear primary tumor site at the nasopharynx (not demonstrated here), yet a regional non-nodal target was noted. A, Axial T2WI shows orbital apex dark T2 SI tissue keeping with fibrotic scarring (arrow). B, This lesion show discrete postcontrast enhancement (arrow) (secondary to PNTS along the ophthalmic nerve) categorized as NI-RADS 3. C, Axial ADC map of the surgical bed shows a corresponding facilitated diffusion (arrow). According to our proposed modifying rules, downgrading to category 2 was done. Follow-up by PET/CT showed no FDG uptake (not demonstrated here) that was confirmed to be post-RTH fibrotic scarring by further follow-up. Note the right temporal lobe after RTH injury.

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Table 1:

Tumor characteristics and scan order of the included population

		Patients (n)	Patients (%)
Subsite	Larynx	12	17.4
	Oral cavity and oropharynx	25	36.2
	Hypopharynx	2	2.9
	Sinonasal	10	14.5
	Skull base	1	1.4
	Nasopharynx	13	18.8
	Salivary	6	8.7
Pathologic grade	Low	14	20.3
	Moderate	37	53.6
	High	18	26.1
Tumor stage^{^a}	Tis	1	1.4
	T1	7	10.14
	T2	24	34.8
	T3	22	31.9
	T4	15	21.7
Scan order	First follow-up	54	78.3
	Second follow-up	8	10.1
	Third follow-up	8	11.6

Note:—Tis indicates carcinoma in situ.
↵a American Joint Committee on Cancer.²⁰

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Table 2:

Results of image analysis by T2 SI, DWI (qualitative and quantitative), NI-RADS, and NI-RADS rescoring for the primary targets

		Standard of Reference
		Negative n (%)	Positive n (%)
NI-RADS	NI-RADS 1	20 (46.51)	1 (3.85)
	NI-RADS 2	15 (34.88)	3 (11.54)
	NI-RADS 3	8 (18.6)	22 (84.62)
T2 SI	Isointense to surrounding tissue	4 (9.3)	1 (3.85)
	Dark	15 (34.88)	1 (3.85)
	Intermediate	5 (11.63)	24 (92.31)
	High	19 (44.19)	0 (0)
DWI	Facilitated	39 (90.7)	2 (7.69)
DWI	Restricted	4 (9.3)	24 (92.31)
NI-RADS combined with T2 and DWI	NI-RADS 1	30 (69.77)	1 (3.85)
	NI-RADS 2	10 (23.26)	2 (7.69)
	NI-RADS 3	3 (6.98)	23 (88.46)

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Table 3:

Diagnostic performance of T2 SI, DWI (qualitative and quantitative), NI-RADS, and NI-RADS rescoring for the detection of LTR for the primary targets

	T2 SI	DWI with ADC ≤1.3	NI-RADS	NI-RADS-DWI-T2 SI
TP (n)	24	24	22	23
TN (n)	38	39	35	40
FP (n)	5	4	8	3
FN (n)	2	2	4	3
Sensitivity (%) (95% CI)	92.31 (74.87–99.05)	92.3 (74.87–99.05)	84.62 (65.13–95.64)	88.46 (69.85–97.55)
Specificity (%) (95% CI)	88.37 (74.92–96.11)	90.7 (77.86–97.41)	81.4 (66.60–91.61)	93.02 (80.94–98.54)
PPV (%) (95% CI)	82.76 (67.64–91.68)	85.71 (70.10–93.89)	73.33 (59.03–84.00)	88.46 (71.84–95.84)
NPV (%) (95% CI)	95.00 (83.32–98.64)	95.12 (83.69–98.67)	89.74 (77.84–95.61)	93.02 (82.10–97.49)
Accuracy (%) (95% CI)	89.86 (80.21–95.82)	91.30 (82.03–96.74)	82.61 (71.59–90.68)	91.30 (82.03–96.74)

Note:—TP indicates true-positive; TN, true-negative.

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Table 4:

Agreement between DWI (qualitative and quantitative), T2 SI, NI-RADS, and NI-RADS combined with DWI and T2 SI for the primary targets and the standard of reference

		Standard of Reference		Agreement
		Negative n (%)	Positive n (%)	Kappa	95% CI	P Value
DWI	Restricted	4 (9.3)	24 (92.31)	0.818	0.68–0.96	<.001
DWI	Facilitated	39 (90.7)	2 (7.69)
T2 SI	Intermediate	5 (11.63)	24 (92.3)	0.789	0.64–0.94	<.001
T2 SI	No abnormality; low or high SI	38 (88.37)	2 (7.69)
NI-RADS combined with T2 and DWI	Category 3	3 (6.98)	23 (88.46)	0.815	0.67–0.96	<.001
NI-RADS combined with T2 and DWI	Categories 1 and 2	40 (93.02)	3 (11.54)
NI-RADS	Category 3	8 (18.6)	22 (84.62)	0.641	9.46–0.82	<.001
NI-RADS	Categories 1 and 2	35 (81.4)	4 (15.38)