role of sonographic imaging in nephrology dr. muhammad bin zulfiqar

Role of Imaging and Interventional Radiologist in Nephrology

Dr. Muhammad Bin ZulfiqarPGR IV FCPS Services Institute of Medical

Sciences / [email protected]

Special thanks to Dr. Samir Haffer MD

Role of Imaging in Nephrology

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

Renal Artery Stenosis

Normal anatomy of the kidney

Paspulati RM et al. Ultrasound Clin 2006 ; 1 : 25 – 41.

Renal parenchyma: cortex & medullary pyramidsRenal sinus: arteries, veins, lymphatics, collecting system, & fat

Renal hilum: Concave, in continuity with renal sinus

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)

Arterial blood supply to the Kidney

Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.

Segmental arteryApical, upper, middle, lower, posterior

Interlobular arteryBetween renal pyramids

Glomerular arteriole

Main renal artery

Arcuate arteryBetween cortex & medulla

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 cmCorrelated to patient’s phenotype particularly height

• Renal length < 8 cm definitely reducedShould be attributed to chronic renal failure

Fiorini F et al. J Ultrasound 2007 ; 10 : 161 – 167.

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.

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

Kidney parenchyma compared to liver parenchyma

Hypoechoic Isoechoic

Hyperechoic

Fiorini F et al. J Ultrasound 2007 ; 10 : 161 – 167.

DiagnosisOverview

• There are two groups of diagnostic studies used to evaluate RAS: Anatomic studies:

1. Renal angiography – the gold standard2. Doppler ultrasonography3. Spiral CT angiography4. MR angiography

Function studies:5. Renal-vein-renin measurement

6. Nuclear imaging with I125iothalamate or DTPA to determine GFR7. Conventional renography8. ACEI renography

DiagnosisDiagnostic 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%

Pourcelot’s resistive index

RI S – ED / S

Normal 50 – 70 %

Abnormal > 80 %

Measurement of PSV

Early systolic peak

Am J Roentgenol – Dec 1995

Biphasic with late systolic peak

Monophasic with late systolic peak

Spectral Doppler of renal arteriesNormal 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

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

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

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.

Renal artery stenosisDirect 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%

Renal artery stenosis / Direct criteriaNon-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

Renal artery stenosis / Direct criteria

PSV: 275 cm/secHigh-grade stenosis

Aliasing in left renal artery

Schäberle W. Ultrasonography in vascular diagnosis.

Springer-Verlag, Berlin Heidelberg, 2nd edition, 2011.

Renal artery stenosis / First Generation CEUS


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

PSV: 293 cm/sec – RI : 0.91Controversial indication of PTA2

Aliasing in left renal arteryRetro-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

Renal artery stenosis / Renal Aortic Ratio


Small right kidney (8.4 cm) PSV (aorta): 102 cm/s

PSV (RRA): 465 cm/s High grade stenosis of RRA

RAR: 4.5

Renal artery stenosis / Indirect criteria

Schäberle W. Ultrasonography in vascular diagnosis.Springer-Verlag, Berlin, 2nd edition, 2011.

PSV: 85.7 cm/sEDV: 47.2 cm/s

RI: 0.64

Left renal hilum Right renal hilum

PSV: 125 cm/secEDV: 58.1 cm/s

RI: 0.75

Δ RI (right – left) > 0.05 → RA stenosis in side of lower RI

Renal artery stenosis / Tardus-Parvus waveSevere stenosis (> 85 % diameter reduction)

Tardus: Longer rise time

Parvus: Low PSV

Freeman SJ. Ultrasound 2004 ; 12 : 69 – 74.

Tardus-Parvus wave

• Mimics Abdominal coarctationWilliam syndromeAortic/mitral valve diseaseLeft ventricle dysfunctionCV medications: after-load reducers

• Exaggerating 25 mg captopril 1 hour before exam

• Minimizing Age – HTN – DM (vessel compliance)


Abdominal aortic aneurysm & renal arteries

Zubarev VZ. Eur Radiol 2001 ; 11 : 1902 – 1915.

Aneurysm arises below origin of both renal arteries

Fibromuscular dysplasiaMoniliform 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

Guidelines for diagnosis of RAS

• Recommended as screening testDuplex US followed by CT angiography (except RF) & MR angiography

• Not recommended as screening testCaptopril renal scintigraphy Plasma renin activityCaptopril testSelective renal vein renin measurements

Hirsch AT et al. J Am Coll Cardiol 2006 ; 47 : 1239 – 1312.

Role of Imaging in Renal Biopsy

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 2010Braak 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.

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 2010Walker TG. Interventional Procedures. Lippincott Williams & Wilkins. (2012) ISBN:1931884862.

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 2010Braak 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.

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 2010Braak 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.

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

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.

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.

Technique of Procedure

• Types of needle– Single core --focal biopsy– Double core—Non focal

• Preferred Site– Lower pole for both native

and transplanted kidney


Technique of Procedure

• Positions:– Transplanted kidney—Supine– Native Kidney

• USG—prone• CT—prone and ipsilateral side up

• CT is preferred– Obese– Tiny– Upper pole lesionsUppot et al. Imaging-Guided Percutaneous Renal Biopsy: Rationale and Approach. AJR:194, June 2010.

Walker TG. Interventional Procedures. Lippincott Williams & Wilkins. (2012) ISBN:1931884862.

Ultrasound Guided

• The core biopsy aims to take the renal cortex, without significant medullary fat, and certainly avoiding the pelvicalyceal system.


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.

Post procedure Care

• Soon after procedure look for– Intraparenchymal hemorrhage– Perinephric hematoma

• Bed rest and vital monitoring for at least 4-6 hours.

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)


Complications

• Minimal perinephric hemorrhage.

• slightly hyperdense subcapsular hemorrhage


Complications

• Arteriogram shows small pseudoaneurysm (arrow).

• Small pneumothorax is seen on CT Lung Window.


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

Role of Imaging in AV Fistula

• Anatomy– Pictorial– Vascular

• Preprocedure vascular mapping• Type of AVF access for hemodialysis• Normal doppler USG of AV fistula

Anatomy of Aortic Arch and Subclavian Artery

Anatomy of Upper Limb Arteries

Type of AVF for Hemodialysis

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

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.

Permcath Placement; Role of Interventional Radiologist

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.

Classification

peripherally inserted central catheters (PICC)non-tunnelled CVCs

e.g. used in ICU or ED for emergent or short-term (<7-10 days) accesse.g. Vascath used for haemodialysis, apheresis, stem cell collection,

etctunnelled CVCs

e.g. Hickman catheters, Broviac line, Permcath implantable ports

e.g. Port-a-Cath, Infus-a-Portmay 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) 20:17-22Scott O. Trerotola, MD. Hemodialysis Catheter Placement and Management1. Radiology 2000; 215:651–658

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.

Advantage of tunneled and Temporary catheter

• Less infection, Long duration (1-12 months), less malpositioning, reliable and comfortable.

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

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.

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 patientScott O. Trerotola, MD. Hemodialysis Catheter Placement and Management1. Radiology 2000; 215:651–658

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


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.


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.

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.

Normal Position of Permcath

• Right internal jugular vein permacath with distal tip at the cavo-atrial junction. No pneumothorax.

Malpositioned Permcath

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

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


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) 20:17-22Scott O. Trerotola, MD. Hemodialysis Catheter Placement and Management1. Radiology 2000; 215:651–658Lund G.B. et.al. Outcome of Tunneled Hemodialysis Catheters Placed by Radiologists’ Radiology 1996; 198:467-472

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role of sonographic imaging in nephrology dr. muhammad bin zulfiqar

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