An evaluation of the clinical diagnostic value of contrast-enhanced ultrasound combined with contrast-enhanced computed tomography in space-occupying lesions of the kidney

Figures & data

Figure 1 The research flowchart.

Abbreviations: CT, computed tomography; NPV, negative predictive value; PPV, positive predictive value; ROC, receiver operating characteristic; Se, sensitivity; Sp, specificity.

Table 1 Pathological results of 378 lesions

Nature	Type	Cases, n (%)
Malignant	Clear cell renal cell carcinoma	238 (62.96)
	Papillary renal cell carcinoma	34 (8.99)
	Cystic renal cell carcinoma	8 (2.12)
	Chromophobe renal cell carcinoma	15 (3.97)
	Transitional cell carcinoma	6 (1.59)
Benign	Hamartoma	41 (10.85)
	Juxtaglomerular cell tumor	2 (0.53)
	Renal tuberculosis	3 (0.79)
	Benign cystic lesion	24 (6.35)
	Hematoma	5 (1.32)
	Oncocytoma	2 (0.53)
Total		378 (100)

Table 2 Comparison of parameters of the time–intensity curves in the benign and malignant lesions

Histopathology	Case (n)	TTP (s)	PI (%)	AUC (s^−1)
Benign	77	53.274±9.832	34.250±8.962	2.501±1.649
Malignant	301	40.751±7.647	48.935±9.725	3.982±2.237
T		9.570	−12.604	−6.498
P-value		<0.001	<0.001	<0.001

Abbreviations: AUC, area under the curve; PI, peak intensity; TTP, time to peak.

Table 3 Comparison of diagnoses of the space-occupying lesions using the three methods (n)

Methods	Results	Histopathology		McNemar χ^2	P-value
		Malignant	Benign
CEUS	Malignant	288	20	1.09	0.296
	Benign	13	57
CECT	Malignant	279	25	0.191	0.771
	Benign	22	52
Combined	Malignant	294	9	0.063	0.804
	Benign	7	68

Abbreviations: CECT, contrast-enhanced computed tomography; CEUS, contrast-enhanced ultrasound.

Table 4 Comparison of diagnostic performance of the three methods in the space-occupying lesions of the kidney (%, 95% CI)

Methods	Sensitivity	Specificity	PPV	NPV
CEUS	95.68% (0.925–0.975)	74.03% (0.625–0.830)	93.51% (0.899–0.959)	81.43% (0.699–0.894)
CECT	92.69% (0.889–0.953)	67.53% (0.557–0.775)	91.78% (0.879–0.945)	70.27% (0.583–0.800)
Combined	97.67% (0.950–0.989)	88.31% (0.785–0.942)	97.03% (0.942–0.985)	90.67% (0.811–0.958)
χ^2	8.540	9.716	7.834	10.002
P-value	0.014	0.008	0.020	0.007

Abbreviations: CI, confidence interval; CECT, contrast-enhanced computed tomography; CEUS, contrast-enhanced ultrasound; NPV, negative predictive value; PPV, positive predictive value.

Figure 2 ROC curves with the three methods.

Note: Diagonal segments are produced by ties.
Abbreviations: CECT, contrast-enhanced CT; CEUS, contrast-enhanced ultrasound; CT, computed tomography; ROC, receiver operating characteristic.

Table 5 Comparison of the area under the ROC curve with the three methods

Test result variables	Area	Standard errora	Asymptotic significanceb	Asymptotic 95% CI
				Lower bound	Upper bound
CEUS	0.849	0.031	0.000	0.788	0.909
CECT	0.803	0.033	0.000	0.737	0.868
Combined CEUS and CECT	0.930	0.022	0.000	0.887	0.973

Notes:

a Under the nonparametric assumption.

b Null hypothesis: true area =0.5.

Abbreviations: CECT, contrast-enhanced computed tomography; CEUS, contrast-enhanced ultrasound; CI, confidence interval; ROC, receiver operating characteristic; sig, significance; Std, standard.