Table 2. Characteristics of excluded studies.

Reference	N	Study type	Age mean (range)	% male	Tumor locations	Treatment	Selection	Reference standard definition tumor	MRI sequences Field strength; sequence orientation slice thickness/ gap in mm (TR/TE in ms); b values and DWI analysis method	Time point MRI	Diagnostic accuracy	TP	FP	FN	TN
Chen et al., 2014	31	Pros	45 (18–68)	84	Primary site and LN of 31 nasopharynx	29 CCRT; 2 RT	All patients with no prior treatment stage III/IV. Excluded if distant metastases before treatment (N = 4) or MRI artefact (N = 2)	Imaging follow-up according to RECIST 1.1 and residual disease was classified by residual soft tissues or thickening of the mucous membrane of the nasopharynx with local bulges	aMRI; 3.0 T; T1 fs tra, sag; T2 tra 5/1; T1C fs tra, cor DWI; 3.0 T; 5/1 (6600/70); b 0, 800; ROI	3 days after start treatment; 20 days after start treatment; 50 days after start treatment	ADC primary ADC LN ADC primary ADC LN ADC primary ADC LN	— — — — — —	— — — — — —	— — — — — —	— — — — — —
Galbán et al., 2009	15	Pros	—	—	Primary site (12) and LN (14) of head and neck	15 CCRT	All patients for CCRT. Exclusion if claustrophobic (N = 2), metal implants (N = 2), withdrew from study (N = 3), inadequate DWI (N = 1).	Histology or imaging 2 mo after end treatment and clinical outcome at 6 mo.	aMRI; 3.0 T; T1; 1/0 (9.9/4.6); T2 fs 4/- (5000/120); T1C; 1/0 (9.9/4.6) DWI; 3.0 T; 4/- (2789/59); b 0, 800; ROI	3 weeks after start treatment	ADC primary ADC LN aMRI primary (Δvolume %) aMRI LN (Δvolume %)	— — — —	— — — —	— — — —	— — — —
Kim et al., 2009	33	Pros	61 (31–78)	79	LN of 11 base of tongue; 10 tonsil; 6 larynx; 1 vallecula; 5 unknown	24 CCRT; 7 RT + immune-therapy	All head/neck cancers with preoperative CCRT and with metastatic lymph nodes. Excluded if death unrelated to treatment (N = 4), claustrophobia (N = 1), withdraw (N = 1) or artefact on DWI (N = 1)	Histology or 6 mo clinical/ imaging follow-up	aMRI; 1.5–3.0 T; T1 tra (600/10); T1C; tra (300/4); T2 tra 5/- (4000/120) and (2000/13, 53, 80, 110); DWI; 1.5-3T; 5/- (40000/89); b 0, 500, 1000; ROI	1 week after start treatment; 2 weeks after end treatment	ADC LN aMRI LN T2 volume ADC LN aMRI LN T2 volume	— — — — — —	— — — — — —	— — — — — —	— — — — — —
King et al., 2010	50	Pros	58 (45–73)	90	Primary site of 9 oral cavity/ oropharynx; 13 hypopharynx; 4 larynx; 1 maxillary sinus; 2 nasal cavity; and 21 LN of not described primary	44 CCRT; 6 RT	All biopsy proven tumors with curative intent of CCRT or RT with stage III or IV. Excluded in no consent (N = 14), artefacts (N = 10) or death before definitive diagnosis (N = 4)	Histology for the primary site and histology or increase in size on serial imaging follow-up >12 mo for lymph nodes; fall in ADC as local failure	aMRI; 1.5 T; T1; T2; T1C. DWI; 1.5 T; fs tra; 4/0 (2000/75); b 0, 100, 200, 300, 400, 500; ROI	6 weeks after end treatment;	Primary/LN ADC 1.4	6	0	1	13
Lell et al., 2000	39	—	—	—	Primary site of 21 oropharynx, oral cavity; 1 naso-pharynx; 17 hypo-pharynx, larynx	CCRT	Locally advanced tumor with CCRT	Histology or clinical follow-up with MRI-based tumor recurrence classified as a localized expansive mass with intermediate signal on T1 and high on T2 with marked enhancement	aMRI; 1.5 T; T1 tra, cor 6/0.6 (500-600/20-30); T2 tra 6/0.6 (2500-3500/30-100); T1C tra,cor 6/0.6 (500-600/20-30); IR cor 6/0.6 (1400/30)	<3 mo after treatment end; 3–6 mo after treatment end	aMRI primary aMRI primary	13 5	— —	— —	11 7
Matoba et al., 2014	35	Pros	66 (33–79)	86	Primary site and LN of 4 oral cavity; 9 oropharynx; 9 hypopharyx; 10 larynx; 3 supraglottic	35 CCRT	All patients treated with CCRT with curative intent. Excluded if patient refuse treatment (N = 2), poor imaging quality (N = 2) or death within 3 mo after treatment (N = 1)	Imaging follow-up every 6 mo with increasing mass or histology proof as indication of tumor recurrence	aMRI; 1.5 T; T1 tra (630/12); T2 tra, cor (4000/90); DWI; 1.5 T; fs tra 6/3 (4000/68); b 0, 90, 800	3 weeks after start treatment	ADC primary ΔADC 0.24 ADC ADC LN ΔADC 0.24 ADC aMRI primary Δvolume aMRI LN Δvolume	— — — — — —	— — — — — —	— — — — — —	— — — — — —
Mukundan et al., 2014	50	Pros	56	80	Primary site of 50 head and neck	11 OP; 26 RT; 13 OP + RT	All patients with treatment without previous treatment and no significant comorbidity	Histology	aMRI; 1.5 T; T1 with and without fs 3-4/0-1; T2 3-4/0-1; T1C fs 3-4/0-1	12 weeks after end treatment; 24 weeks after end treatment	aMRI primary aMRI primary	— —	— —	— —	— —

Characteristics of the 7 excluded studies are shown. See Table 1 for abbreviations.