Diagnostic efficacy of diffusion-weighted imaging and semiquantitative and quantitative dynamic contrast-enhanced magnetic resonance imaging in salivary gland tumors

Table 1 Locations, numbers, and frequencies of salivary gland tumors

Location	n (%)
Unilateral parotid gland	61 (83.6)
Submandibular gland	6 (8.2)
Minor salivary gland	3 (4.1)
Bilateral parotid gland	2 (2.7)
Sublingual gland	1 (1.4)

n: Number of salivary gland tumors

Table 2 Numbers of benign and malignant salivary gland tumors

Benign SGTs	n (%)	Malignant SGTs	n (%)
Warthin’s tumor	18 (24.7)	Squamous cell carcinoma	11 (15.1)
Pleomorphic adenoma	14 (19.2)	Adenoid cystic carcinoma	3 (4.1)
Inflammatory process	12 (16.4)	Malignant lymphoma	3 (4.1)
Lipoma	4 (5.5)	Adenocarcinoma	1 (1.4)
Benign cystic lesions	1 (1.4)	Mucoepidermoid carcinoma	1 (1.4)
		Carcinoma ex pleomorphic adenoma	1 (1.4)
Other benign lesions	1 (1.4)	Acinic cell carcinoma	1 (1.4)
		Follicular dendritic cell sarcoma	1 (1.4)
		Salivary duct carcinoma	1 (1.4)
Total	50 (68.5)		23 (31.5)

SGTs: Salivary gland tumors; n: Number of salivary gland tumors

Table 3 Mean ADC values and quantitative dynamic contrast-enhanced magnetic resonance imaging parameters of different histopathologic salivary gland tumors

	Pleomorphic adenoma	Warthin’s tumor	Other benign tumors	Malignant tumors	P value
ADC (× 10−3 mm2/s)	1.61 ± 0.26 (a)	0.72 ± 0.09 (b)	0.77 ± 0.19 (b)	0.96 ± 0.33 (b)	< 0.001
Ktrans (min−1)	0.42 ± 0.35	0.75 ± 0.55	0.57 ± 0.37	0.77 ± 0.56	0.131
Kep (min−1)	0.69 ± 0.33 (a)	6.2 ± 3.13 (b)	1.95 ± 0.94 (c)	1.72 ± 0.92 (c)	< 0.001
Ve	0.65 ± 0.25 (a)	0.11 ± 0.04 (b)	0.3 ± 0.12 (c)	0.48 ± 0.24 (ac)	< 0.001

Data are shown as the mean ± SD. One-way ANOVA was used. abc: Indicates that means with the same letters in the same column are not significantly different; P < 0.05 indicates a statistically significant difference among the groups. ADC: Apparent diffusion coefficient; K_trans: Volume transfer constant between blood plasma and the extracellular extravascular space; K_ep: Flux rate constant between the EES and plasma; V_e: EES fractional volume; EES: Extracellular extravascular space.

Table 4 Semiquantitative dynamic contrast-enhanced magnetic resonance imaging parameters of different histopathologic salivary gland tumors

	TIC Pattern, n(%)				Tpeak (s)	WR (%)
	A	B	C	D
Pleomorphic adenomas	14 (70.0)	0 (0)	0 (0)	0 (0)	202.74 ± 21.48 (a)	-
Warthin’s tumors	0 (0)	18 (66.7)	0 (0)	0 (0)	20.26 ± 11.72 (b)	59.33 ± 10.99 (a)
Other benign tumors	4 (20.0)	4 (14.8)	10 (45.5)	0 (0)	74.94 ± 75.47 (c)	17.89 ± 14.99 (b)
Malignant tumors	2 (10.0)	5 (18.5)	12 (54.5)	4 (100)	60.60 ± 55.78 (c)	18.48 ± 18.38 (b)
P value	< 0.001				< 0.001	< 0.001

Data are shown as the mean ± SD. One-way ANOVA was used. abc: Indicates that the means with the same letters in the same column are not significantly different. TIC: Time intensity curve; T_peak: Time to peak; WR: Washout ratio; n: Number of salivary gland tumors.

Table 5 Comparison of pleomorphic adenomas, Warthin’s tumors, and malignant salivary gland tumors by ROC analysis using ADC, T_peak, K_trans, K_ep, and V_e values

Variable	Cut-off	AUC (95% CI)	Sensitivity	Specificity	PPV	NPV	P value
Pleomorphic adenomas
ADC value	> 1.1	0.977 (0.911-0.998)	1.000	0.898	0.700	1.000	< 0.001
Tpeak	> 120	0.947 (0.868-0.986)	1.000	0.898	0.700	1.000	< 0.001
Ktrans	≤ 0.46	0.702 (0.584-0.804)	0.857	0.627	0.353	0.949	0.005
Kep	≤ 1.14	0.926 (0.840-0.974)	0.929	0.831	0.565	0.980	< 0.001
Ve	≥ 0.4	0.849 (0.746-0.922)	0.929	0.729	0.448	0.977	< 0.001
Warthin’s tumors
ADC value	≤ 0.8	0.742 (0.626-0.837)	0.944	0.582	0.425	0.970	< 0.001
Tpeak	≤ 19.1	0.869 (0.769-0.936)	0.667	0.909	0.706	0.893	< 0.001
WR	> 43	0.981 (0.917-0.999)	0.944	0.909	0.773	0.980	< 0.001
Ktrans	> 0.3	0.577 (0.455-0.692)	0.889	0.346	0.308	0.905	0.291
Kep	> 2.44	0.973 (0.905-0.997)	1.000	0.855	0.692	1.000	< 0.001
Ve	≤ 0.17	0.958 (0.883-0.991)	1.000	0.909	0.783	1.000	< 0.001
Malignant tumors
ADC value	> 0.7	0.541 (0.420-0.658)	0.783	0.440	0.391	0.815	0.569
Tpeak	≤ 120	0.531 (0.410-0.649)	0.913	0.360	0.396	0.900	0.648
WR	≤ 49	0.562 (0.441-0.678)	1.000	0.300	0.397	1.000	0.351
Ktrans	> 0.53	0.599 (0.477-0.712)	0.652	0.600	0.429	0.789	0.194
Kep	≤ 3.7	0.592 (0.471-0.706)	1.000	0.300	0.397	1.000	0.160
Ve	> 0.35	0.702 (0.584-0.804)	0.696	0.660	0.485	0.825	0.001

ADC (× 10⁻³ mm²/s): Apparent diffusion coefficient; T_peak (s): Time to peak; K_trans (min⁻¹): Volume transfer constant between blood plasma and the extracellular extravascular space; K_ep (min⁻¹): Flux rate constant between the EES and plasma; V_e: EES fractional volume; AUC: Area under the ROC curve; CI: Confidence interval; PPV: Positive predictive value; NPV: Negative predictive value; WR (%): Washout ratio; EES: Extracellular extravascular space.