Current status of low dose multi-detector CT in the urinary tract

Table 1 Major indications for evaluation of the urinary tract using computed tomography

Urinary colic

Hematuria

Complicated infection

Neoplasm

Renal donor evaluation

Congenital anomalies

Structural abnormalities

Abdominal trauma

Table 2 Radiation dose, scanning parameters, and diagnostic performances of computed tomography examination using low dose protocols in urolithiasis

Authors	Yr	Low dose CT protocols					Diagnostic performance			Effective dose (mSv)
		CT scanner	kVp	mA (mAs)	Pitch	S.T. (mm)	Sensitivity (%)	Specificity (%)	Accuracy (%)
Liu et al[7]	2000	SDCT	120	(280)	2	7	97	96	97	2.8
Meagher et al[8]	2001	SDCT, 4MDCT	120-130	63-130	1.4-1.8	5	93	NA	NA	3.5 (2.8-4.5)
Hamm et al[9]	2002	4MDCT	120	70	2	5	96	97	NA	1.5
Heneghan et al[10]	2003	SDCT	140	100 (76)	1.5	5	NA	NA	90-94	6.4
		4MDCT			0.75					11
Tack et al[11]	2003	4MDCT	120	(30)	1.5	3	90-95	94-100	93-98	1.2-1.9
Knöpfle et al[12]	2003	4MDCT	120	70	2	5	98	97	NA	0.97 (male)/ 1.35 (female)
Kluner et al[13]	2006	16MDCT	120	20 (6.9)	1.43	5	97	95	NA	0.5-0.7
Poletti et al[14]	2007	4MDCT	120	74 (30)	1.25	5	86-96	97-100	NA	NA

CT: Computed tomography; SDCT: Single-detector row CT; MDCT: Multi-detector row CT; NA: Non applicable; S.T.: Slice thickness; mSv: MiliSivert.

Table 3 Computed tomography protocols for suspected urolithiasis in our institute

CT scanner	GE (64 MDCT)	Siemens (64 MDCT)
Scan range	Top of kidney-pubic symphysis	Top of kidney-pubic symphysis
Detector collimation (mm)	64 × 0.625	24 × 1.2
Pitch	1.375	1.2
Rotation time (s)	0.5	0.5
Kvp	120	120
mA	150-450	Reference mA = 160
Noise index	25 (30 if follow-up exam)
Kernel	Standard	B31F
Reconstruction mode	Plus
Slice thickness (mm)	5 (2.5)	5 (2.5)
Slice overlap	5 (2.5)	5 (2.5)

CT: Computed tomography; MDCT: Multi-detector row CT.

Table 4 Radiation dose and computed tomography scanning parameters of computed tomography urography using standard dose and low dose protocols

Authors	Yr	CT scanner	Acquisiton phase	kVp	mA (mAs)	Pitch	Effective dose (mSv)	Supplement
Standard CT urographic protocols
Caoili et al[26]	2002	4MDCT	Unenhanced	120	150-240	0.75	25-35
			Nephrographic		100-280	0.75
			Excretory		150-280	1.5
Nawfel et al[25]	2004	4MDCT	Unenhanced	120	(155-200)	1.0-1.25	6.4 ± 1.3
			Nephrographic		(155-200)	1.0-1.25	2.5 ± 0.34
			Excretory		(165-185)	0.65-1.0	5.9 ± 1.5
Low dose CT urographic protocols
Coppenrath et al[27]	2006	4MDCT	Excretory	90	(15-100)	0.875-1.75	0.78 (male)/1.08 (female)
		16MDCT		100	(17-100)	1-1.5	1.06-1.19 (male)
							0.76-0.86 (female)
Kemper et al[28]	2007	4MDCT	Excretory	120	(70)	1.25	2.7 (male)/4.1(female)
Yanaga et al[29]	2009	40MDCT	Excretory	80	(300)	0.781	2.9	Adaptive noise reduction filter
Kekelidze et al[30]	2010	16MDCT	Unenhanced	120	(55)	0.75	3.4	AEC
			Enhanced		(165)	1.25	9.8	Split-bolus technique

CT: Computed tomography; MDCT: Multi-detector row CT; AEC: Automatic exposure control; mSv: MiliSivert.

Table 5 Computed tomography protocols for computed tomography urography in our institute

	Non-contrast	Post-contrast1
Scan range	Top of kidney to base of bladder	Top of kidney to base of bladder
Detector collimation (mm)	64 × 0.625	64 × 0.625
Pitch	1.375	1.375
kVp	120	120
mA	150-450	150-450
Noise index	25 (30 for follow-up exam)	10 (< 60 kg)
		12.5 (61-90 kg)
		15 (> 90 kg)
Table speed (mm/rotation)	55	55

¹Delayed scan is supplementarily acquired if whole ureteral opacification is not seen on post-contrast scan.

Table 6 Radiation dose and computed tomography protocols for renal donors

Author	Yr	CT scanner	Acquisition phase	kVp	mA(mAs)	Pitch	CTDIvol in mGy	DLP in mGy cm	Supplements
Kim et al[49]	2003	4MDCT	Unenhanced	120	200	1.5	10.19	NA
			Renal CTA				12.88	NA
			Excretory				10.19	NA
Wintersperger et al[50]	2005	16MDCT	Abdominal CTA	120	400 (200)	1	15.6	673.9
				100			10.0	447.0
Sahani et al[45]	2007	16MDCT	Renal CTA	140	(210)	0.94	25 ± 3	NA	AEC
				120			17 ± 4	NA	Using NI of 15
				100			12 ± 3	NA
Zamboni et al[42]	2010	64MDCT	Low dose 4-phase	120	50-150	NA	NA	2021 ± 545
			Low dose 3-phase				NA	1501 ± 418	AEC
			Low dose 2-phase				NA	981 ± 381	Using NI of 15.86
			Low dose 2-phase*				NA	676 ± 284

mGy: Mili Gray; CT: Computed tomography; MDCT: Multi-detector row CT; CTA: CT angiography; AEC: Automatic exposure control; NI: Noise index; DLP: Dose-length product; 4-phase: Unenhanced CT of the abdomen and pelvis, arterial phase CT of the abdomen, venous phase CT of the abdomen, and excretory phase CT of the abdomen and pelvis; 3-phase: Unenhanced CT of the abdomen and pelvis, arterial phase CT of the abdomen, and excretory phase CT of the abdomen and pelvis; 2-phase: Unenhanced CT of the abdomen and pelvis and combined phase scan (using split-bolus technique) of the abdomen and pelvis; 2-phase*: Unenhanced CT of the abdomen and pelvis and a combined phase scan (using split-bolus technique) of the abdomen.

Table 7 Computed tomography protocols for living renal donors in our institute

	Unenhanced	Arterial	Excretory
Scan range	Dome of liver-iliac crest	Dome of liver-iliac crest	Top of kidney-iliac crest
Detector collimation (mm)	64 × 0.625	64 × 0.625	64 × 0.625
Pitch	1.375	1.375	1.375
kVp	120	120	100
mA	150-450	150-550 (150-800 for patient > 135 kg)	150-450
Noise index	20	28 (< 60 kg)	18
		32 (61-90 kg)
		35 (> 90 kg)
Table speed (mm/rotation)	55	55	55

After arterial phase scanning, plain radiograph image (kidney-ureter-bladder) is acquired at 6 min delay after the injection of contrast medium starts. Excretory phase images are acquired immediately.