Usefulness of hounsfield unit and density in the assessment and treatment of urinary stones

Table 1 Some critical hounsfield unit values in recent literature

	Ref.	Year	Hounsfield units	Affected parameters
Prediction of stones	Motley et al[4]	2001	Density < 76 /mm	Non-calcium stone
	Patel et al[5]	2009	Mean, 879 ± 230	Calcium oxalate monohydrate stone
			Mean, 844 ± 346	Apatite stone
			Mean, 550 ± 74	Cystine stone
	Spettel et al[7]	2013	< 500	Uric acid stone
Prediction of Radio-opacity	Chua et al[9]	2012	> 498.5	Radio-opaque stone
	Huang et al[10]	2009	> 800 (ureteral stones)	Radio-opaque
			< 200	Radiolucent
Predicting the success of ESWL	Hameed et al[15]	2013	> 1350	Low ESWL success
	El-Assmy et al[16]	2011	> 1000	Low ESWL success
	El-Assmy et al[17]	2013	≤ 600 and stone length ≤ 12 mm (in children)	High ESWL success
	Ouzaid et al[18]	2012	> 970	Low ESWL success
	Foda et al[19]	2013	> 934	Low ESWL success
Use in PNL	Gücük et al[20]	2012	< 677.5	Low PNL success
	Gücük et al[21]	2013	< 677.5	Increases success with flexible nephroscope use
Use in URS	Kim et al[22]	2014	Any	No effect
Medical expulsive treatment	Erturan et al[24]	2013	Any	No effect

ESWL: Extracorporeal shock wave lithotripsy.