Diagnostic performance of the modified Korean Thyroid Imaging Reporting and Data System for thyroid malignancy according to nodule size: a comparison with five society guidelines
	    		
		   		
		   			
		   		
	    	
    	- Author:
	        		
		        		
		        		
			        		Dong Gyu NA
			        		
			        		
			        		
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			        		Wooyul PAIK
			        		
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			        		Jaehyung CHA
			        		
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			        		Hye Yun GWON
			        		
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			        		Suh Young KIM
			        		
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			        		Roh-Eul YOO
			        		
			        		
		        		
		        		
		        		
			        		
			        		Author Information
			        		
 - Publication Type:1
 - From: Ultrasonography 2021;40(4):474-485
 - CountryRepublic of Korea
 - Language:English
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		        	Abstract:
			       	
			       		
				        
				        	 Purpose:The aim of this study was to evaluate the diagnostic performance of the modified Korean Thyroid Imaging Reporting and Data System (K-TIRADS) compared with five society risk stratification systems (RSSs) according to nodule size. 
				        	
Methods:In total, 3,826 consecutive thyroid nodules (≥1 cm) with final diagnoses in 3,088 patients were classified according to five RSSs. The K-TIRADS was modified by raising the biopsy size threshold for low-suspicion nodules and subcategorizing intermediate-suspicion nodules. We assessed the performance of the RSSs as triage tests and their diagnostic accuracy according to nodule size (with a threshold of 2 cm).
Results:Of all nodules, 3,277 (85.7%) were benign and 549 (14.3%) were malignant. In small thyroid nodules (≤2 cm), the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) had the highest reduction rate of unnecessary biopsies (76.3%) and the lowest sensitivity (76.1%). The modified K-TIRADS had the second highest reduction rate of unnecessary biopsies (67.6%) and sensitivity (86.6%). The modified K-TIRADS and ACR TI-RADS had the highest diagnostic odds ratios (P=0.165) and the highest areas under the curve (P=0.315). In large nodules (>2 cm), the sensitivity of the ACR TI-RADS for malignancy was significantly lower (88.8%) than the sensitivities of the modified K-TIRADS and other RSSs, which were very high (98.7%-99.3%) (P<0.001).
Conclusion:The modified K-TIRADS allows a large proportion of unnecessary biopsies to be avoided, while maintaining high sensitivity and diagnostic accuracy for small malignant tumors and very high sensitivity for large malignant tumors. 
            