Role of Doppler US in Renal Artery Stenosis. Renal Biopsy. IV fistula. Permcath Placement. Role of Interventional Radiologist in management of AV fistula. We will discuss all these aspects under US guidance.

1. Role of Imaging and Interventional
Radiologist in Nephrology
Dr. Muhammad Bin Zulfiqar
PGR IV FCPS Services Institute of Medical
Sciences / Hospital
radiombz@gmail.com
Special thanks to Dr. Samir Haffer MD

2. Role of Imaging in Nephrology
• Role of Imaging in Renal Artery Stenosis.
• Renal Biopsy.
• IV fistula.
• Permcath Placement.

3. Renal Artery Stenosis

4. Normal anatomy of the kidney
Paspulati RM et al. Ultrasound Clin 2006 ; 1 : 25 – 41.
Renal parenchyma: cortex & medullary pyramids
Renal sinus: arteries, veins, lymphatics, collecting system, & fat
Renal hilum: Concave, in continuity with renal sinus

5. Anatomy of renal arteries
RRA: Usually passes posterior to inferior vena cava
LRA: Usually courses posterior to left renal vein
Multiple renal arteries in 25% (inferior polar artery from aorta)

6. Arterial blood supply to the Kidney
Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.
Segmental artery
Apical, upper, middle, lower, posterior
Interlobular artery
Between renal pyramids
Glomerular arteriole
Main renal artery
Arcuate artery
Between cortex & medulla

7. Renal dimensions
• Length of normal kidney: 9 – 14 cm
Right kidney smaller than left kidney
• Discrepancy > 2 cm between two kidneys:
Considered significant & needs further evaluation
• Renal length between 8 – 9 cm
Correlated to patient’s phenotype particularly height
• Renal length < 8 cm definitely reduced
Should be attributed to chronic renal failure
Fiorini F et al. J Ultrasound 2007 ; 10 : 161 – 167.

8. Measurement of parenchymal & cortical thickness
Cortical thickness: Normal 8 – 10 mm
Parenchymal thickness: Normal 14 – 18 mm
Tuma J et al. European course book: Genitourinary ultrasound.
European Foundation of Societies of Ultrasound in Medicine & Biology.

9. Classification of renal parenchymal echogenicity
4 types based of US appearance
Hypoechoic compared to liver
Isoechoic compared to liver
Hyperechoic compared to liver
Isoechoic to renal sinus
Normal
Normal
Pathological
Pathological
Grade 0
Grade I
Grade II
Grade III

10. Kidney parenchyma compared to liver parenchyma
Hypoechoic Isoechoic
Hyperechoic
Fiorini F et al. J Ultrasound 2007 ; 10 : 161 – 167.

11. Diagnosis
Overview
• There are two groups of diagnostic studies used to evaluate RAS:
Anatomic studies:
1. Renal angiography – the gold standard
2. Doppler ultrasonography
3. Spiral CT angiography
4. MR angiography
Function studies:
1. Renal-vein-renin measurement
2. Nuclear imaging with I125iothalamate or DTPA to determine GFR
3. Conventional renography
4. ACEI renography

12. Diagnosis
Diagnostic Study Sens. Spec. PPV NPV
Renal Vein Renins 62% 70-88%
Doppler Ultrasonography 80-98% 98% 99% 88-97%
Conventional Renography 75% 85% 33%
ACEI Renography 75 -90% 94% 92% 88%
CT angiography 92% 98% 87% 99%
MRA 100% 93% 90% 100%

13. Pourcelot’s resistive index
RI S – ED / S
Normal 50 – 70 %
Abnormal > 80 %

14. Measurement of PSV
Early systolic peak
Am J Roentgenol – Dec 1995
Biphasic with late systolic peak
Monophasic with late systolic peak

15. Spectral Doppler of renal arteries
Normal values
• PSV < 180 cm/sec
• Renal Aortic Ratio (RAR) < 3
• Resistive index (RI) < 0.70
• ∆ RI (right – left) < 0.05
• Acceleration Time (AT) < 0.07 sec
• Acceleration Index (AI) > 3.5 m/s2

16. Renal artery stenosis
1 – 5% of hypertensive population
• Atherosclerosis
• Fibromuscular dysplasia (FMD)
• Dissection
• Embolization
• Aortic coarctation
• Renal Artery Aneurysm
• Arteritis
• Congenital
• Neurofibromatosis
• Irradiation
> 95 % of cases

17. Renal artery stenosis
Atherosclerosis
> 90%
FMD
< 10%
Age After age of 50 Young
Gender More common in males More common in females
Location Proximal 1 cm of main RA
Branching points
Middle of renal artery
Others (carotids)
Post-stenotic
dilatation
Rare Frequent

18. Clinical risk factors for renovascular HTN
• Abrupt onset of severe HTN: diastolic >120 mm Hg
• Accelerated or malignant HTN: grade III or IV retinopathy
• HTN refractory to appropriate three-drug regimen
• Onset of hypertension before age 30 or after age 60
• HTN with rapidly progressive renal failure
• Renal failure that develops in response to ACE inhibitor
• HTN associated with upper abdominal bruit
• Episodes of recurrent severe HTN & pulmonary edema
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.

19. Renal artery stenosis
Direct signs
Focal color aliasing
Color bruit
Turbulence
PSV > 180 cm/sec
Renal Aortic Ratio > 3.5
Indirect signs
AT > 0.07 sec
AI < 3 m/s2
Δ RI (right – left) > 5 %
Significant stenosis
(50 – 85% diameter reduction)
Sensitivity: 79 – 91%
Specificity: 73 – 97%
Severe stenosis
(> 85 % diameter reduction)
Sensitivity: 95%
Specificity: 97%

20. Renal artery stenosis / Direct criteria
Non-significant stenosis (< 50% diameter stenosis)
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Plaque in anterior wall of LRA
PSV: 148 cm/sec
Color Doppler US Power Doppler US
Better visualization of plaque

21. Renal artery stenosis / Direct criteria
PSV: 275 cm/sec
High-grade stenosis
Aliasing in left renal artery
Schäberle W. Ultrasonography in vascular diagnosis.
Springer-Verlag, Berlin Heidelberg, 2nd edition, 2011.

22. Renal artery stenosis / First Generation CEUS
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Baseline color Doppler
RRA not identified
Aliasing of SMA origin
Pulse Doppler image
PSV > 300 cm/s
Severe stenosis of RRA
IV contrast agent
RRA visualized
Focal color aliasing

23. PSV: 293 cm/sec – RI : 0.91
Controversial indication of PTA2
Aliasing in left renal artery
Retro-aortic course of LRV
1 Schäberle W. Ultrasonography in vascular diagnosis. Springer-Verlag, Berlin, 2nd edition, 2011.
2 Jaeger KA et al. Ultraschall in Med 2007 ; 28 : 28 – 31.
Renal artery stenosis / Direct criteria

24. Renal artery stenosis / Renal Aortic Ratio
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Small right kidney (8.4 cm) PSV (aorta): 102 cm/s
PSV (RRA): 465 cm/s High grade stenosis of RRA
RAR: 4.5

25. Renal artery stenosis / Indirect criteria
Schäberle W. Ultrasonography in vascular diagnosis.
Springer-Verlag, Berlin, 2nd edition, 2011.
PSV: 85.7 cm/s
EDV: 47.2 cm/s
RI: 0.64
Left renal hilumRight renal hilum
PSV: 125 cm/sec
EDV: 58.1 cm/s
RI: 0.75
Δ RI (right – left) > 0.05 → RA stenosis in side of lower RI

26. Renal artery stenosis / Tardus-Parvus wave
Severe stenosis (> 85 % diameter reduction)
Tardus: Longer rise time
Parvus: Low PSV
Freeman SJ. Ultrasound 2004 ; 12 : 69 – 74.

27. Tardus-Parvus wave
• Mimics Abdominal coarctation
William syndrome
Aortic/mitral valve disease
Left ventricle dysfunction
CV medications: after-load reducers
• Exaggerating 25 mg captopril 1 hour before exam
• Minimizing Age – HTN – DM (vessel compliance)
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.

28. Abdominal aortic aneurysm & renal arteries
Zubarev VZ. Eur Radiol 2001 ; 11 : 1902 – 1915.
Aneurysm arises below origin of both renal arteries

29. Fibromuscular dysplasia
Moniliform aspect of RRA
Typical FMD in middle third of RRA
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
PSV 250 cm/sec
No parallelism of RRA walls

30. Guidelines for diagnosis of RAS
• Recommended as screening test
Duplex US followed by
CT angiography (except RF) & MR angiography
• Not recommended as screening test
Captopril renal scintigraphy
Plasma renin activity
Captopril test
Selective renal vein renin measurements
Hirsch AT et al. J Am Coll Cardiol 2006 ; 47 : 1239 – 1312.

31. Role of Imaging in Renal
Biopsy

32. Role of Imaging in Renal Biopsy
• Imaging-guided percutaneous renal biopsy to sample
renal parenchyma
– Safe
– Minimally invasive technique
• for the evaluation of malignancy
• Diffuse renal parenchymal disease.
• Current biopsy techniques involve ultrasound or CT
guidance wit small-gauge needles.
• The risks are minimal.
• Transjugular renal biopsy
Uppot et al. Imaging-Guided Percutaneous Renal Biopsy: Rationale and Approach. AJR:194, June 2010
Braak SJ, Van Melick HH, Onaca MG et-al. 3D cone-beam CT guidance, a novel technique in renal biopsy-results in
41 patients with suspected renal masses. Eur Radiol. 2012;22 (11): 2547-52.

33. Renal Biopsy
• Native Kidneys (CT & USG)
• Transplanted Kidney (USG)
• Non-focal or non-targeted e.g. Diffuse Renal
Parenchymal Disease
• Cystic renal lesions
• Focal or targeted (i.e. directed at a lesion)
Uppot et al. Imaging-Guided Percutaneous Renal Biopsy: Rationale and Approach. AJR:194, June
2010
Walker TG. Interventional Procedures. Lippincott Williams & Wilkins. (2012) ISBN:1931884862.

34. Indications of Renal Biopsy
• Focal lesions not characterised on diagnostic
imaging
• Renal failure with unknown cause (typically a
nephropathy)
• Deteriorating renal function in transplant
patient
Uppot et al. Imaging-Guided Percutaneous Renal Biopsy: Rationale and Approach. AJR:194, June 2010
Braak SJ, Van Melick HH, Onaca MG et-al. 3D cone-beam CT guidance, a novel technique in renal biopsy-results in 41
patients with suspected renal masses. Eur Radiol. 2012;22 (11): 2547-52.
Walker TG. Interventional Procedures. Lippincott Williams & Wilkins. (2012) ISBN:1931884862.

35. Indications in Focal Mass Lesions
• known extra-renal malignancy
• Suspected renal lymphoma
• Prior to ablation therapy
• Multiple or bilateral renal masses
• Diagnostic dilemma of infection/malignant
mass
Uppot et al. Imaging-Guided Percutaneous Renal Biopsy: Rationale and Approach. AJR:194, June 2010
Braak SJ, Van Melick HH, Onaca MG et-al. 3D cone-beam CT guidance, a novel technique in renal biopsy-results in 41
patients with suspected renal masses. Eur Radiol. 2012;22 (11): 2547-52.
Walker TG. Interventional Procedures. Lippincott Williams & Wilkins. (2012) ISBN:1931884862.

36. Contraindications of Renal Biopsy
• Uncooperative patient
• Uncorrectable bleeding diathesis (abnormal
coagulation indices)
Uppot et al. Imaging-Guided Percutaneous Renal Biopsy: Rationale and Approach. AJR:194, June 2010

37. Preprocedure Requirements
• Lab Values
– complete (full) blood count:
• platelet > 50000/mm3
– coagulation profile:
• international normalized ratio (INR) ≤ 1.5
• normal prothrombin time (PT)/partial thromboplastin
time (PTT)
• written informed consent
• assessment of patient's cooperation for
procedure
Uppot et al. Imaging-Guided Percutaneous Renal Biopsy: Rationale and Approach. AJR:194, June 2010.
Walker TG. Interventional Procedures. Lippincott Williams & Wilkins. (2012) ISBN:1931884862.

38. Equipment
• Single or co-axial needle
set: usually an 18G core
biopsy needle
• 1% lidocaine / lignocaine
and midazolam (for
sedation)
• histopathology
department pots for 'dry'
and 'wet' core (slides and
biopsy jar)
Uppot et al. Imaging-Guided Percutaneous Renal Biopsy: Rationale and Approach. AJR:194, June 2010.

39. Technique of Procedure
• Types of needle
– Single core --focal biopsy
– Double core—Non focal
• Preferred Site
– Lower pole for both native
and transplanted kidney
Uppot et al. Imaging-Guided Percutaneous Renal Biopsy:
Rationale and Approach. AJR:194, June 2010.
Walker TG. Interventional Procedures. Lippincott Williams &
Wilkins. (2012) ISBN:1931884862.

40. Technique of Procedure
• Positions:
– Transplanted kidney—Supine
– Native Kidney
• USG—prone
• CT—prone and ipsilateral side up
• CT is preferred
– Obese
– Tiny
– Upper pole lesions
Uppot et al. Imaging-Guided Percutaneous Renal Biopsy: Rationale and Approach. AJR:194, June 2010.
Walker TG. Interventional Procedures. Lippincott Williams & Wilkins. (2012) ISBN:1931884862.

41. Ultrasound Guided
• The core biopsy aims to take
the renal cortex, without
significant medullary fat, and
certainly avoiding the
pelvicalyceal system.
Uppot et al. Imaging-Guided Percutaneous Renal Biopsy:
Rationale and Approach. AJR:194, June 2010.
Walker TG. Interventional Procedures. Lippincott Williams &
Wilkins. (2012) ISBN:1931884862.

42. CT Guided Renal Biopsy
• CT images show the core-biopsy needle positioned in the
lower pole of left kidney. After the biopsy procedure
a perirenal haematoma is noted as an immediate
complication.

43. CT Guided Renal Biopsy
• CT images show the
core-biopsy needle
positioned in the lower
pole of left kidney.
After the biopsy
procedure
a perirenal haematoma
is noted as an
immediate
complication.

44. Post procedure Care
• Soon after procedure look for
– Intraparenchymal hemorrhage
– Perinephric hematoma
• Bed rest and vital monitoring for at least 4-6
hours.

45. Complications
• Perinephric (retroperitoneal) or intra-renal
hematoma
• hamaturia
• arteriovenous fistula or pseudoaneurysm
• colonic injury (very rare with image guidance)
• pneumothorax (very rare with image
guidance)
Uppot et al. Imaging-Guided Percutaneous Renal Biopsy: Rationale and Approach. AJR:194, June 2010.
Walker TG. Interventional Procedures. Lippincott Williams & Wilkins. (2012) ISBN:1931884862.

46. Complications
• Minimal perinephric
hemorrhage.
• slightly hyperdense
subcapsular hemorrhage
Uppot et al. Imaging-Guided Percutaneous Renal Biopsy: Rationale
and Approach. AJR:194, June 2010.

47. Complications
• Arteriogram shows
small pseudoaneurysm
(arrow).
• Small pneumothorax is
seen on CT Lung
Window.
Uppot et al. Imaging-Guided Percutaneous Renal Biopsy: Rationale and
Approach. AJR:194, June 2010.

48. Take Home Message
• With the progressive increase in the
– Number of incidentally discovered renal masses,
– Increased use of percutaneous ablation as a treatment
alternative for the management of RCC
– Improvements in immunohistochemistry techniques
• imaging-guided renal biopsies will continue to serve as
a useful tool for the evaluation and management of
renal diseases.
• Biopsy after a full imaging work-up can help prevent
unnecessary and potentially morbid surgical and
ablation procedures in a substantial number.
Uppot et al. Imaging-Guided Percutaneous Renal Biopsy: Rationale and Approach. AJR:194, June 2010.
Silverman et alber of patients. Renal Masses in the Adult Patient: The Role of Percutaneous Biopsy. Radiology:
Volume 240: Number 1—July 2006

49. Role of Imaging in AV Fistula
• Anatomy
– Pictorial
– Vascular
• Preprocedure vascular mapping
• Type of AVF access for hemodialysis
• Normal doppler USG of AV fistula

50. Anatomy of Aortic Arch and Subclavian Artery

51. Anatomy of Upper
Limb Arteries

63. SVC

65. Type of AVF for Hemodialysis

74. 3000

75. aaa

81. Complications of AV Fistula
• Stenosis and Occlusion
• Aneurysm and Pseudoaneurysm
• Infected and non infected collections
– Hematoma
– Seroma
– Lymphocele
• Arterial steel syndrome
• High cardiac output failure

97. Take Home Message
• Doppler USG and clinical findings helps in long
term management of fistula
• Its management is multidisciplinary:
Nephrologist, Vascular Surgeon, Interventional
Radiologist
• Stenosis in early postop period may be due to
edema
• Doppler USG is central to prevention,
detection and management of complications.

98. Permcath Placement; Role of
Interventional Radiologist

99. Idea Behind Permcath
• Central venous catheters (CVC) or lines (CVL)
refer to a wide range of central venous access
devices but can broadly be divided into four
categories. They may be inserted by
physicians, surgeons or radiologists.

100. Classification
peripherally inserted central catheters (PICC)
non-tunnelled CVCs
 e.g. used in ICU or ED for emergent or short-term (<7-10
days) access
 e.g. Vascath used for haemodialysis, apheresis, stem cell
collection, etc
tunnelled CVCs
 e.g. Hickman catheters, Broviac line, Permcath
implantable ports
 e.g. Port-a-Cath, Infus-a-Port
 may be located in the chest or arm (brachial)
 may be single or dual lumen
K.D. and Surgical Placement of Central Venous Catheters. Cardiovasc Intervent Radiol (1997) 20:17-22
Scott O. Trerotola, MD. Hemodialysis Catheter Placement and Management1. Radiology 2000; 215:651–658

101. Permacath
• Permacath (or permcath)
are a type of tunneled
central venous catheter. It
is a split catheter - this
means that the two
lumens have unequal
lengths with one opening
a few centimeters distal to
the other giving a
staggered or step tip
appearance. It is often
used for hemodialysis.
1. Funaki B. Central venous access: a primer for the
diagnostic radiologist. AJR Am J Roentgenol. 2002;179 (2):
309-18.

102. Advantage of tunneled and Temporary catheter
• Less infection, Long duration (1-12 months),
less malpositioning, reliable and comfortable.

103. Port Catheter resovoirs
• A Port is a catheter placed in a vein of
the neck, chest or arm under
ultrasound guidance. This long
catheter has it's tip in the main vein
near the heart and has a reservoir
implanted under the skin surface
• long term intravenous therapy like
chemotherapy.
• The reservoir or port can be accessed
through the skin surface with a special
needle.
• Once the tiny incision heals the entire
system is beneath the skin and less
prone to infection. Port catheters can
remain implanted for years.
Scott O. Trerotola, MD. Hemodialysis Catheter
Placement and Management1. Radiology
2000; 215:651–658

104. PICC Catheter
•
A PICC line is a catheter
which is placed in the arm
with ultrasound guidance to
Superior Vena Cava. It has no
reservoir ,exits through the
skin and can only be left in
place for up to six months.
• The venous access catheters
described above are placed
in the angiography room
utilizing both ultrasound and
x-ray guidance under sterile
conditions.

105. Characteristics of an Ideal Catheter
• Easy to insert and remove
• Inexpensive
• Free of infection
• Free of fibrin sheath (“invisible to body”)
• Does not cause venous thrombosis or stenosis
• Delivers high flow (>400ml/min) reliably
• Durable
• Comfortable and acceptable to the patient
Scott O. Trerotola, MD. Hemodialysis Catheter Placement and Management1. Radiology 2000; 215:651–658

106. Sites
• most commonly including:
• internal jugular vein
• subclavian vein
• femoral vein (typically only short-term access)
• For PICCs and implantable ports)
– brachial
– basilic
– cephalic veins
K.D. and Surgical Placement of Central Venous Catheters. Cardiovasc Intervent Radiol (1997) 20:17-22
Scott O. Trerotola, MD. Hemodialysis Catheter Placement and Management1. Radiology 2000; 215:651–658

107. Preprocedure Mapping
• Look for SVC, Right Brachiocephalic vein, Internal
jugular Vein and subclavian vein under USG
guidence for any evidence of
• Stenosis and occlusion
• Thrombosis
• Occlusion
• Variation in anatomy
• Collaterals
• Accessory Veins.
K.D. and Surgical Placement of Central Venous Catheters. Cardiovasc Intervent Radiol (1997) 20:17-22
Scott O. Trerotola, MD. Hemodialysis Catheter Placement and Management1. Radiology 2000; 215:651–658

108. Technique
• Informe and written consent,
• Sedation
• Aseptic measures
• One small incision in the skin commonly in the
lower neck. Using ultrasound guidance, the
vein is punctured with a needle (usually the
jugular vein at the base of the neck), and a
small guide wire is advanced into the superior
vena cava.

109. Technique
• A second small skin incision may be made below the
first, and a tunnel under the skin is then created.
• Using USG guidance, the catheter is placed through
the tunnel into the vein, and the tip of the catheter is
placed into the SVC.
• Finally, stitches applied.

110. Normal Position of Permcath
• Right internal
jugular vein
permacath with
distal tip at the
cavo-atrial
junction. No
pneumothorax.

111. Malpositioned Permcath
• The proximal
permacath tip is
malpositioned in
the right internal
jugular vein.

112. Complications
• pneumothorax
• haemothorax
• infection
• mediastinal haematoma
• infusothorax
• arterial placement
• perforation of vein needing a stent
• pinch off syndrome
• retained guidewire
• guidewire shearing and fragment embolisation
K.D. and Surgical Placement of Central Venous Catheters. Cardiovasc Intervent Radiol (1997) 20:17-22
Scott O. Trerotola, MD. Hemodialysis Catheter Placement and Management1. Radiology 2000; 215:651–658

113. Take Home Message
• Radiological placement is consistently more
reliable than surgical placement. There are fewer
placement complications and fewer catheter
infections overall.
• It is convenient for the patient, quick, time
saving, and cost effective
• Interventional radiologists
– placement and
– management
– research and development of hemodialysis catheters
K.D. and Surgical Placement of Central Venous Catheters. Cardiovasc Intervent Radiol (1997) 20:17-22
Scott O. Trerotola, MD. Hemodialysis Catheter Placement and Management1. Radiology 2000; 215:651–658
Lund G.B. et.al. Outcome of Tunneled Hemodialysis Catheters Placed by Radiologists’ Radiology 1996; 198:467-472

114. THANK YOU