Author's Accepted Manuscript
Renal Imaging: Duplex Ultrasound, CTA, MRA and Angiography Ali F. AbuRahma M.D., Michael Yacoub M.D.
www.elsevier.com/locate/engana-
PII: DOI: Reference:
S0895-7967(14)00019-2 http://dx.doi.org/10.1053/j.semvascsurg.2014.06.001 YSVAS50426
bound
To appear in: ĆSemin Vasc Surg
Cite this article as: Ali F. AbuRahma M.D., Michael Yacoub M.D., Renal Imaging: Duplex Ultrasound, CTA, MRA and Angiography, ĆSemin Vasc Surg , http://dx.doi.org/10.1053/j.semvascsurg.2014.06.001 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1
Renal Imaging: Duplex Ultrasound, CTA, MRA and Angiography Ali F. AbuRahma, M.D. Professor of Surgery Chief, Vascular & Endovascular Surgery Director, Vascular Surgery Fellowship and Residency Programs Medical Director, Vascular Laboratory Co‐Director, Vascular Center of Excellence Michael Yacoub, M.D. Vascular Surgery Fellow Department of Surgery West Virginia University 3110 MacCorkle Ave., SE, Charleston, WV 25304 Phone: 304‐388‐4887; Fax: 304‐388‐4879; e‐mail: [email protected]
2 Introduction:
Renal artery stenosis (RAS) is present in approximately 1‐5% of all patients with hypertension
and is one of the most common causes of severe hypertension.[1] Catheter‐based arteriography is considered the gold standard for the diagnosis of RAS, even with its associated morbidity. Currently, there is no universally accepted screening text for RAS. Most clinicians utilize renal duplex ultrasound (RDU) imaging; however, others use magnetic resonance angiography (MRA) or contrast computed tomography angiography. [2] Renal Artery Duplex Ultrasound (RDU):
RDU imaging has several advantages over CTA or MRA, such as being noninvasive, relatively
inexpensive, and widely available; however, it can be technically demanding. Since its early introduction in detecting RAS, [3, 4] several studies have reported differing results of RDU imaging in detecting severe RAS using different Doppler parameters. [2‐16]
Presently, there is no consensus on specific RDU criteria for the diagnosis of significant RAS.
Several others reported the value of renal peak systolic velocities (PSVs) ranging from 100 to 200 cm/s with different accuracies. [6, 11‐13] One of the most reliable Doppler parameters is based on the renal‐to‐ aortic peak systolic ratio (RAR). An RAR >3.5 predicts ≥60% RAS with a sensitivity of 84% to 91% and a specificity of 95% to 97%. [3‐6]
Technical Consideration:
RDU Assessment: RDU testing should be done by registered vascular technologists in an
accredited vascular laboratory (e.g. the Intersocietal Commission for the Accreditation of Vascular
3 Laboratories). We use a Philips system (IU 22 instrumentation) with low‐frequency 1 to 5 MHz curved linear phase array transducers. Every effort should be made to use a Doppler angle of ≤60° to provide consistency in Doppler velocity measurements.
Patients are examined after fasting overnight in the anterior and lateral decubitus positions so
that all portions of the main renal artery from the origin to the hilum are visualized. Hilar examination is performed by the flank approach with the patient in the left and right decubitus positions. This is particularly useful in obese patients and those with excessive bowel gas. The length of each kidney is recorded using B‐mode imaging from the flank approach.
Renal parenchymal Doppler signals are also obtained during this examination. A 0° Doppler
angle and a sample volume size of ~2 mm are used to record spectral waveforms from the renal parenchyma of the lower and upper poles of each kidney. Renal artery occlusion is usually diagnosed when there is no flow signal in the renal artery and a low amplitude velocity signal from the renal parenchyma. The abdominal aorta is visualized in the sagittal plane at the level of the origin of the superior mesenteric artery, the probe is rotated 90°, and each renal artery origin is located using the left renal vein as a landmark.
We obtain Doppler samplings and velocity waveforms from the origin, proximal, middle, and
distal renal arteries. PSVs and en‐diastolic velocities (EDVs) along the renal arteries from the origin to the hilum are also recorded. The presence of post‐stenotic turbulence is noted, which is defined by the presence of focal, bi‐directional Doppler flow.
The renal‐to‐aortic peak systolic ratio is calculated by dividing the highest PSV of the renal artery
by the PSV in the aorta (Figures 1A‐1C demonstrating imaging and localization of renal ostium).
Our Clinical Experience:
4
We conducted the largest study to date to compare RDU imaging versus angiography and assess
various published Doppler criteria. [17] Three hundred and thirteen patients (606 renal arteries) had both RDU and angiography. RAS was classified into: normal, 285 & RAR >3.5
60
(53.28,66.02)
94
(91.02,96.19)
86
78
80
PSV >180 & RAR >3.6
71
(65.17,76.94)
87
(83.03,90.22)
78
82
80
PSV >200 & RAR >3.6
71
(64.7,76.53)
88
(84.33,91.25)
79
82
81
PSV >250 & RAR >3.6
65
(59.17,71.53)
91
(88.3,94.26)
83
80
81
PSV >150 & RAR >3.7
69
(62.85,74.87)
91
(88.3,94.26)
84
82
82
PSV >180 & RAR >3.7
69
(62.85,74.87)
91
(88.3,94.26)
84
82
82
PSV >200 & RAR >3.7
68
(62.39,74.45)
92
(88.63,94.51)
84
81
82
PSV >240 & RAR >3.7
65
(58.72,71.11)
93
(90.67,95.95)
87
80
82
PSV >150 & RAR >3.8
66
(59.63,71.95)
92
(89.65,95.24)
85
80
82
PSV >180 & RAR >3.8
66
(59.63,71.95)
92
(89.65,95.24)
85
80
82
PSV >200 & RAR >3.8
65
(59.17,71.53)
93
(89.99,95.48)
86
80
82
PSV >220 & RAR >3.8
64
(57.81,70.26)
93
(90.67,95.95)
86
80
82
PSV >230 & RAR >3.8
64
(57.35,69.84)
93
(90.67,95.95)
86
79
81
PSV >180 & RAR >3.9
63
(56.9,69.42)
93
(90.33,95.72)
86
79
81
PSV >200 & RAR >3.9
63
(56.9,69.42)
93
(90.67,95.95)
86
79
81
PSV >230 & RAR >3.9
61
(55.08,67.72)
94
(91.37,96.43)
87
79
81
27 Table III Accuracy of CTA in Diagnosing Renal Artery Stenosis Series
Year
Number of patients
Sensitivity (%)
Specificity (%)
Galanski et al (41)
1994
52
95
92
Olbricht et al (42)
1995
62
98
94
Bereqi et al (43)
1997
300
100
98.2
Kim et al (44)
1998
50
90
97
Wittenberg et al (45)
1999
82
94
98
Vasbinder et al (46)
2004
402
64
92
Rountas et al (47)
2007
58
94
93
28 Figure Legend Figure 1A: Normal B‐mode Doppler and left renal vein. Figure 1B: Color imaging and left renal vein. Figure 1C: Doppler and localization of left renal ostium. Figure 2: Receiver operator curve (ROC) for ≥60% stenosis. Figure 3A: Computed tomographic angiography (CTA) showing normal renal arteries (arrow). Figure 3B: CTA showing high‐grade stenosis of the right renal artery (arrow). Figure 4A: Conventiona digital subtraction angiography (DSA) of normal renal arteries. Figure 4B: DSA showing severe stenosis of the left renal artery (arrow). Figure 4C: DSA showing FMD of the right renal artery (arrow).
29 Figure 1A
30 Figure 1B
31 Figure 1C
32 Figure 2
>60% Stenosis ROC Curves
1.0
Sensitivity
0.8
0.6
0.4
PSV, AUC = 0.85 EDV, AUC = 0.71 Renal Aortic Ratio, AUC = 0.82
0.2
0.0 0.0
0.2
0.4
0.6
0.8
1.0
1 - Specificity PSV vs EDV: p
Renal Imaging: Duplex Ultrasound, CTA, MRA and Angiography Ali F. AbuRahma M.D., Michael Yacoub M.D.
www.elsevier.com/locate/engana-
PII: DOI: Reference:
S0895-7967(14)00019-2 http://dx.doi.org/10.1053/j.semvascsurg.2014.06.001 YSVAS50426
bound
To appear in: ĆSemin Vasc Surg
Cite this article as: Ali F. AbuRahma M.D., Michael Yacoub M.D., Renal Imaging: Duplex Ultrasound, CTA, MRA and Angiography, ĆSemin Vasc Surg , http://dx.doi.org/10.1053/j.semvascsurg.2014.06.001 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1
Renal Imaging: Duplex Ultrasound, CTA, MRA and Angiography Ali F. AbuRahma, M.D. Professor of Surgery Chief, Vascular & Endovascular Surgery Director, Vascular Surgery Fellowship and Residency Programs Medical Director, Vascular Laboratory Co‐Director, Vascular Center of Excellence Michael Yacoub, M.D. Vascular Surgery Fellow Department of Surgery West Virginia University 3110 MacCorkle Ave., SE, Charleston, WV 25304 Phone: 304‐388‐4887; Fax: 304‐388‐4879; e‐mail: [email protected]
2 Introduction:
Renal artery stenosis (RAS) is present in approximately 1‐5% of all patients with hypertension
and is one of the most common causes of severe hypertension.[1] Catheter‐based arteriography is considered the gold standard for the diagnosis of RAS, even with its associated morbidity. Currently, there is no universally accepted screening text for RAS. Most clinicians utilize renal duplex ultrasound (RDU) imaging; however, others use magnetic resonance angiography (MRA) or contrast computed tomography angiography. [2] Renal Artery Duplex Ultrasound (RDU):
RDU imaging has several advantages over CTA or MRA, such as being noninvasive, relatively
inexpensive, and widely available; however, it can be technically demanding. Since its early introduction in detecting RAS, [3, 4] several studies have reported differing results of RDU imaging in detecting severe RAS using different Doppler parameters. [2‐16]
Presently, there is no consensus on specific RDU criteria for the diagnosis of significant RAS.
Several others reported the value of renal peak systolic velocities (PSVs) ranging from 100 to 200 cm/s with different accuracies. [6, 11‐13] One of the most reliable Doppler parameters is based on the renal‐to‐ aortic peak systolic ratio (RAR). An RAR >3.5 predicts ≥60% RAS with a sensitivity of 84% to 91% and a specificity of 95% to 97%. [3‐6]
Technical Consideration:
RDU Assessment: RDU testing should be done by registered vascular technologists in an
accredited vascular laboratory (e.g. the Intersocietal Commission for the Accreditation of Vascular
3 Laboratories). We use a Philips system (IU 22 instrumentation) with low‐frequency 1 to 5 MHz curved linear phase array transducers. Every effort should be made to use a Doppler angle of ≤60° to provide consistency in Doppler velocity measurements.
Patients are examined after fasting overnight in the anterior and lateral decubitus positions so
that all portions of the main renal artery from the origin to the hilum are visualized. Hilar examination is performed by the flank approach with the patient in the left and right decubitus positions. This is particularly useful in obese patients and those with excessive bowel gas. The length of each kidney is recorded using B‐mode imaging from the flank approach.
Renal parenchymal Doppler signals are also obtained during this examination. A 0° Doppler
angle and a sample volume size of ~2 mm are used to record spectral waveforms from the renal parenchyma of the lower and upper poles of each kidney. Renal artery occlusion is usually diagnosed when there is no flow signal in the renal artery and a low amplitude velocity signal from the renal parenchyma. The abdominal aorta is visualized in the sagittal plane at the level of the origin of the superior mesenteric artery, the probe is rotated 90°, and each renal artery origin is located using the left renal vein as a landmark.
We obtain Doppler samplings and velocity waveforms from the origin, proximal, middle, and
distal renal arteries. PSVs and en‐diastolic velocities (EDVs) along the renal arteries from the origin to the hilum are also recorded. The presence of post‐stenotic turbulence is noted, which is defined by the presence of focal, bi‐directional Doppler flow.
The renal‐to‐aortic peak systolic ratio is calculated by dividing the highest PSV of the renal artery
by the PSV in the aorta (Figures 1A‐1C demonstrating imaging and localization of renal ostium).
Our Clinical Experience:
4
We conducted the largest study to date to compare RDU imaging versus angiography and assess
various published Doppler criteria. [17] Three hundred and thirteen patients (606 renal arteries) had both RDU and angiography. RAS was classified into: normal, 285 & RAR >3.5
60
(53.28,66.02)
94
(91.02,96.19)
86
78
80
PSV >180 & RAR >3.6
71
(65.17,76.94)
87
(83.03,90.22)
78
82
80
PSV >200 & RAR >3.6
71
(64.7,76.53)
88
(84.33,91.25)
79
82
81
PSV >250 & RAR >3.6
65
(59.17,71.53)
91
(88.3,94.26)
83
80
81
PSV >150 & RAR >3.7
69
(62.85,74.87)
91
(88.3,94.26)
84
82
82
PSV >180 & RAR >3.7
69
(62.85,74.87)
91
(88.3,94.26)
84
82
82
PSV >200 & RAR >3.7
68
(62.39,74.45)
92
(88.63,94.51)
84
81
82
PSV >240 & RAR >3.7
65
(58.72,71.11)
93
(90.67,95.95)
87
80
82
PSV >150 & RAR >3.8
66
(59.63,71.95)
92
(89.65,95.24)
85
80
82
PSV >180 & RAR >3.8
66
(59.63,71.95)
92
(89.65,95.24)
85
80
82
PSV >200 & RAR >3.8
65
(59.17,71.53)
93
(89.99,95.48)
86
80
82
PSV >220 & RAR >3.8
64
(57.81,70.26)
93
(90.67,95.95)
86
80
82
PSV >230 & RAR >3.8
64
(57.35,69.84)
93
(90.67,95.95)
86
79
81
PSV >180 & RAR >3.9
63
(56.9,69.42)
93
(90.33,95.72)
86
79
81
PSV >200 & RAR >3.9
63
(56.9,69.42)
93
(90.67,95.95)
86
79
81
PSV >230 & RAR >3.9
61
(55.08,67.72)
94
(91.37,96.43)
87
79
81
27 Table III Accuracy of CTA in Diagnosing Renal Artery Stenosis Series
Year
Number of patients
Sensitivity (%)
Specificity (%)
Galanski et al (41)
1994
52
95
92
Olbricht et al (42)
1995
62
98
94
Bereqi et al (43)
1997
300
100
98.2
Kim et al (44)
1998
50
90
97
Wittenberg et al (45)
1999
82
94
98
Vasbinder et al (46)
2004
402
64
92
Rountas et al (47)
2007
58
94
93
28 Figure Legend Figure 1A: Normal B‐mode Doppler and left renal vein. Figure 1B: Color imaging and left renal vein. Figure 1C: Doppler and localization of left renal ostium. Figure 2: Receiver operator curve (ROC) for ≥60% stenosis. Figure 3A: Computed tomographic angiography (CTA) showing normal renal arteries (arrow). Figure 3B: CTA showing high‐grade stenosis of the right renal artery (arrow). Figure 4A: Conventiona digital subtraction angiography (DSA) of normal renal arteries. Figure 4B: DSA showing severe stenosis of the left renal artery (arrow). Figure 4C: DSA showing FMD of the right renal artery (arrow).
29 Figure 1A
30 Figure 1B
31 Figure 1C
32 Figure 2
>60% Stenosis ROC Curves
1.0
Sensitivity
0.8
0.6
0.4
PSV, AUC = 0.85 EDV, AUC = 0.71 Renal Aortic Ratio, AUC = 0.82
0.2
0.0 0.0
0.2
0.4
0.6
0.8
1.0
1 - Specificity PSV vs EDV: p
