6. Renal transplant recipient who has a rise of his S Cr by 12 μmol/L. The renal vein is visualized by the duplex scan. The transplant artery signals are shown below.
- Will you explain the Duplex scan findings?
- What is your management plan?
Thank you All, LET US BREAK IT DOWN
What do you expect the normal PSV to be?
Can we have renal artery stenosis with this PSV?
Can we have a reversal of flow with this PSV and this RI?
Do you think the rise of creatinine is significant?
This Duplex scan findings may explain renal arteriovenous fistula?
We should ask if the patient underwent renal biopsy
Or leceration renal vein or artery ++
the RI is acceptable in patient after transplantation
the rise of creatinine should be compared with the basic creatinine if it is less than 15% this rise has no significant However we should repeate it again
It is not RENAL artery stenosis
Because
In RTAS
PSV > 300 cm/s in combination with a reduced RI (< 0.5) will increase the index of suspicion especially if there the early renal function is decreased.
RTAS surveillance: PSV values between 200–300 cm/s in this setting are a marker for RTAS and should be identified for ongoing surveillance.
A PSV of > 300 cm/s will have a more acceptable specificity and should be used as the diagnostic threshold.
Yes, Dr Ghalia
Hmmm. ‘laceration of renal vein or artery’.
I do not understand that.
I like your Dr Ghalia.
Do you mean to state that intra-renal AV shunt may be a complication of renal allograft biopsy?
Thank you Ghalia
You know now the right answer
– the normal peak systolic velocity (PSV) of the main renal artery is less than 80 – 150 cm/sec, while the end-diastolic velocity (EDV) is 20 – 50cm/sec.
–Normal transplant kidneys have an average RI of 0.71 ± 0.11, and kidneys in acute rejection have an RI of 0.77 ± 0.11. Using a cutoff of 0.8 results in a sensitivity of 38% and a specificity of 63% for acute rejection. A resistive index > 1 was only seen in renal vein thrombosis.
-So we have high normal PSV suspect renal artery stenosis.
and high resistive index for DD: rejection, ATN, renal vein thrombosis, and obstruction.
I will do MRA, if normal, we will proceed with renal biopsy.
Is this rise of 12 micromol/L in a single value enough for us to contemplate renal allograft biopsy?
Normal PSV 60-100 cm/s(transplant graft reach to 150)
RAS associated with PSV 250-300cm/s & low RI
RI 0.81 borderline ( or mildly elevated)
creatinine increase `0.13mg/dl which is insignificant
Reversed diastolic flow associated with lower RI
These mild changes with insignificant creatinine increased can be rechecked after good hydration
yes, Dr Ban
Thank you
The normal PSV of the main renal artery is less than 80 – 150 cm/sec.
Renal a. stenosis is usually suspected when PSV is more than 200 cm/sec.
Reversed flow can not happen with this PSV and RI
The rise in serum creatinine level is not significant.
Yes, Dr Huda.
the rise of serum creatinine by 12 umol/l is nonsignificant.
all the U/S parameters are still within the normal range(even with borderline PSV, and RI). It is operator-dependent. just observation and repeat renal function and doppler U/S.
Yes Dr Weam
Thank you, All
There is no reversal of flow as you see in the signal above the ZERO line. Signals below the Zero-Line indicate a flow away from the probe (kidney vein), IT IS NOT A REVERSAL OF FLOW.
PSV is within the normal range (10-210 cm/sec). Also, we need always to compare the PSV of the transplant renal artery with the PSV of the nearby external iliac artery.
RI is slightly elevated, but given that the renal vein is visualised and no evidence of hydronephrosis, It could be a parenchymal or an operator-dependent variation.
A rise in creatinine by 12 is insignificant.
In conclusion, apparently NORMAL Doppler. Do nothing
This scenario was designed to see how many of you went and read about doppler signals. There is a reward for the correct answer.
Those with the correct answer, please email me a screenshot of your answer to get your reward.
Many thanks, my academic brother Prof Halawa for your precise reply that concludes the discussion in this thread.
Thank you professor. Some times when we give an ACEi for a recipient to treat polycythemia, develops rapid elevation of creatinine. Should we investigate this patient aggressively for RAS, even after improvement of creat?
thank you prof. Ahmad for this precise, easy to know and remember hints in duplex renal ultrasound
Thank you, prof Halawa,
Thank you, Professor Halawa
thank you , sir
Thank you prof
Yes Dr Saini, I appreciate your approach
What do you expect the normal PSV to be?
Rumack CM. Diagnostic ultrasound. St. Louis: Elsevier
Mosby, 2011
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Can we have renal artery stenosis with this PSV?
Renal duplex : RI slightly high 0.81,could be due to internsic renal disease PSV 177 so It is not indicate renal artery stenosis artery stenosis.
Cardiovascular Diagnosis and Therapy. All rights reserved. Cardiovasc Diagn Ther 2019;9(Suppl 1):S2-S13 | http://dx.doi.org/10.21037/cdt.20
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Can we have a reversal of flow with this PSV and this RI?
The resistive index is high (normal range 50-70)
D.D:-
ATN
Acute or chronic transplant rejection
renal vein thrombosis
Drug toxicity
Ureteric obstraction
Perinephric fluid collection
In this case, I think the closest to the diagnosis is ATN
==================================================================
Do you think the rise of creatinine is significant?
A rise of creatinine by S Cr by 12 mmol/L—– graft biopsy in this case to exclude parenchymal rrenal disease.
rise in serum creatinine is considered significant if 15% or more increase from the baseline
reversed flow RI more than 1
PSV normally less than 120.
Renal artery stenosis of more than 60% is expected when PSV is exceeding 180-200.
reversal of flow can happened with this PSV and RI as its indicative of higher resistance to the arterial flow.
The rise of creatinine is significant in the setting of increased RI and PSV.
reference:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3567456/
rising creatinine insignificant
no evidence of RAS because PSV is more than 300 and TSV less> than 300 and RI is less than 0.5
· What do you expect the normal PSV to be? Normal PSV is 170-210 cm/sec. So, PSV is normal
· Can we have renal artery stenosis with this PSV?
Less probable.
· Can we have a reversal of flow with this PSV and this RI?
RI is elevated. But there is no hydronephrosis or RVT. So, may be it is parenchymal (acute rejection or ATN) if persists or only operator-dependent
· Do you think the rise of creatinine is significant? No, it is not significant.
The doppler study is helping us to denote for specific grAFT diseases
in this case, we have mildly elevated PSV 170 and in the graft, acceptable till 150 with mild jihj RI along with mild elevation in s creatinin ,so all features collectively do not looks like RAS, but i totally agree with Dr Ban that it could be due to mild dehydration.
The main findings of this duplex scan were:
– PSV = 177
– EDV = 33
– IR =0.81
Peak Systolic Velocity (PSV) = when it has a value above 180 cm/s, it suggests the presence of stenosis greater than 60%. A study by Radermacher et reached a sensitivity of 96.7% and a specificity of 98%, with this cutoff point.
End Diastolic Velocity (EDV) – normal values between 25-50 cm/s.
The resistance index (RI) measures the degree of intrarenal artery impedance. With normal values of 0.6-0.7. When above it can represent stenosis, but it can also mean intrinsic kidney disease (type: nephroangiosclerosis, hypertension, tubular-interstitial disease, diabetes mellitus)
Analyzing the results, we can see that there is no renal artery stenosis.
Faced with a normal Doppler result, we need to reassess the causes of acute worsening:
– Acute rejection: we will need a biopsy for evaluation
– Drugs: evaluate immunosuppressive drugs and measure their serum dosage
– Assess urinary volume: if there is a decrease in volume, we may have an obstructive factor to be investigated through an imaging exam.
Accepted normal duplex scan.
Follow up renal function monthly if worsening renal profile to repeat duplex scan.
Ø PSV 177 cm/ sec
Ø RI 0.81
Ø Both within normal
Even the Cr rise is insignificant.
No management is required for now
Normal PSV 45-180 cm/sec Normal RI:0.5-0.7
here no significant increase in PSV ,but high RI which may indicate intrinsic renal disease like rejection ,ATN
Peak systolic velocity (psv): 177cm/sec which is normal (120-180).
End Diastolic velocity (EDV):33 which is normal (20-50).
RI=0.8, normal (0.6-0.7).
No reversal of blood flow
The rise in creatinine is not significant
So the patient need only follow up.
1.Duplex scan finding
Peak systolic velocity (PSV) : 177cm/sec ……normal (120-180)
End diastolic velocity (EDV) : 33 cm/sec……..normal (20-50)
Resistive index (RI) :0.81 normal (0.6-0.7)
causes of high RI : early transplant period , rejection ,ATN,CIN toxicity , renal vein thrombosis
Low: RAS
Rise in creatinine is insignificant.
Just followup by kidney function and duplex.
Duplex scan in the above scenario is normal and showed no evidence of renal artery stenosis as is evident by PSV of renal artery 177cm/sec (normal range) and RI of 0.81(Resistive index =Peak systolic velocity – end diastolic velocity/ Peak systolic velocity….Normal RI -0.6 to 0.8) with no reversal of flow and creatinine rise by 12umol/l which is not significant .Therefore, only observation and only close monitoring with repeat duplex ,renal function test and proteinuria is needed.
REFERENCE:
1- Sharfuddin A. Renal relevant radiology: imaging in kidney transplantation. Clin J Am Soc Nephrol. 2014 Feb;9(2):416-29
The image reveals :
PSV( peak systolic velocity) 177 cm/sec . The peak systolic velocity (PSV) in the main RA and its branches should be less then 120 cm/s [11]. The velocity slowly decreases in the intrarenal arteries as they branch into the kidney.
EDV( end diastolic velocity) 33 cm/sec
RI ( resistive index) 0.81. The resistive index (RI) measures the degree of intrarenal arterial impedance and is calculated using the following formula: ([PSV – end-diastolic velocity]/PSV). The values in the main RA are higher in the hilar region (0.65 ± 0.17) than in the more distal small arteries, and they are lowest in the interlobar arteries (0.54 ± 0.20). Intrinsic renal diseases (i.e. nephroangiosclerosis, hypertension, tubular-interstitial disease, diabetes mellitus, and severe bradycardia) can cause an increase of RI, even in the presence of normal serum creatinine levels. In clinical practice the value of RI 0.7 is used to discriminate between normal and pathologic resistance to flow.
Four criteria are used to diagnose significant proximal stenosis or occlusion of the RA.
1- increase in PSV higher than 180 cm/s suggest the presence of a stenosis of more than 60% , while an end-diastolic velocity greater than 150 cm/s suggests a degree of stenosis greater than 80%. Using a cut-off value of 180 cm/s and RA diameter reduction of more than 50%, reaching a sensitivity of 96.7% and a specificity of 98%. A PSV greater than 200 cm/s has been suggested as the threshold for Doppler diagnosis of 60% reduction of the RA diameter . This criterion yielded a positive predictive value (PPV) of 60%, a negative predictive value (NPV) of 95%, and an overall accuracy of 79%.
2- comparison of PSV values obtained in the prerenal abdominal aorta with those measured in the RAs, the so-called renal/aortic ratio (RAR) . The use of the RAR instead of the absolute PSV value is preferable since hypertension itself can cause increased PSV velocities in all the vessels in hypertensive patients . In normal conditions, RAR is lower than 3.5. If PSV obtained in the prerenal abdominal aorta is abnormally low (less than 40 cm/s), RAR cannot be used.
3- identification of RAs with no detectable Doppler signal
4- visualization of color artifacts such as aliasing at the site of the stenosis and the presence of turbulence at Doppler evaluation indicating the presence of a significant stenosis upstream.
Granata A, Fiorini F, Andrulli S, Logias F, Gallieni M, Romano G, Sicurezza E, Fiore CE. Doppler ultrasound and renal artery stenosis: An overview. J Ultrasound. 2009 Dec;12(4):133-43. doi: 10.1016/j.jus.2009.09.006. Epub 2009 Oct 12. PMID: 23397022; PMCID: PMC3567456.
What is your management plan?
The role of RI in identifying graft dysfunction has been studied with conflicting results. Most studies suggest that while evaluation of RI has not been able to identify specific causes of early graft dysfunction, elevated RI is significantly correlated with an increased incidence of delayed graft function. Even then, evaluation of RI falls short of effectively predicting the occurrence of graft dysfunction with only a moderate degree of estimated diagnostic accuracy .
Elevated RI not only results from intrarenal factors but may also be secondary to systemic factors, such as heart rate, patient age, hypotension, and aortic stiffness. In a study by Naesens et al, RI was evaluated at predetermined time-points of 3, 12, and 24 months after transplantation during protocol biopsies and the authors found that RIs reflected the recipient characteristics like older age and not renal allograft histological features. In the same study, RI measured at time of biopsies for graft dysfunction were significantly higher than RI measured at time of protocol biopsies, corroborating the association of RI elevation and graft dysfunction noted in other studies.
So ,we would exclude the mentined causes and follow this patient RFT and do serial U/S to detect if these observed changes are progressive or not.
Chen FK, Sanyal R. Serial changes in renal allograft resistive index. J Bras Nefrol. 2020 Oct-Dec;42(4):391-392. doi: 10.1590/2175-8239-JBN-2020-E003. PMID: 33258466; PMCID: PMC7860657.
The renal artery vessels normally demonstrate alow-resistance waveform with an RI,0.7. The normal peak velocity of the transplant renal artery is in the range of 170–210 cm/sec, whereas the renal venous flow is flat with low-velocity waveforms . Accordingly PSV and EDV are normal but the RI is mildly increased. And the mild rise of s creatinine is not significant, These finding may be normal this patient need follow up with renal function test and Doppler ultrasound.
REFERENCES:
. Jakobsen JA, Brabrand K, Egge TS, Hartmann A: Dopplerexamination of the allografted kidney. Acta Radiol 44: 3–12,2003.
Will you explain the Duplex scan findings?
Peak Systolic Velocity (PSV) 177 cm/sec (normal 120-180 cm/sec), End Diastolic Velocity (EDV) 33 cm/sec (normal 20-50 cm/sec), and Resistive index (RI) 0.81(normal RI 0.6-0.7)
Diagnosis: normal variation
DD of high RI: first transplant period, ATN, Renal vein thrombosis, CNI toxicity, ureteric obstruction, and peri-nephric fluid collection.
DD of low RI: renal artery stenosis.
Rise of serum creatinine is insignificant.
What is your management plan?
Follow up duplex and renal function tests.
Doppler ultrasound of renal artery and vein shows PSV 177 cm-% and RI0.81; no evidence of renal artery stenosis and no reversal flow of vein; it indicates no renal vein thrombosis
Management includes well hydration with close drug levels and kidney function.
In this case, PSV=177 cm/sec , EDV=33 cm/sec and RI=0.8
The PSV and EDV are in normal range and RI is mildly increased. But, creatinine rise is not significant. So, this patient needs only follow up.
Peak systolic velocity is 177cm/sec (normal range: 170-210cm/sec), resistivity index 0.81 (normal: 0.5-0.7)
High RI may occur with ATN, rejection or with CNI toxicity.
the rise of serum creatinine with 12 μmol/L is not significant but require closer monitoring and follow up for early detection of further rise.The patient should be advised to have good oral hydration and to be compliant on his medications.
Sharfuddin A. Renal relevant radiology: imaging in kidney transplantation. Clinical Journal of the American Society of Nephrology. 2014 Feb 7;9(2):416-29
this duplex scan of graft shows PSV of renal artery 177cm/sec which is within normal range.
there is a reasonable level of consensus that a value of 250 cm/s is still within the normal range, whereas higher velocities predict significant stenosis with high sensitivity and specificity
So this is normal with no renal artery stenosis.
a resistive index is 0.81 slightly increased which might indicate parenchymal disease.
follow up with another duplex , CNI level , proteinuria , kidney function is important
Management Plan
the increase in creatinine is insignificant yet as it increased by 12 mmol/L and should be followed up if it become doubled this will be sign of AKI.
ensure compliance to medication , control of BP , good hydration , absence of UTI and other factors that might affect graft function.
Renal transplant vascular complications: the role of Doppler ultrasoundAntonio Granata, Silvia Clementi, Francesco Londrino, J Ultrasound. 2015 Jun; 18(2): 101–107.
This is Doppler ultrasound of graft high normal RI and Normal PSV.
should be followed keenly for observation for any rejection / MAHA/ intrarenal small vessel obstruction. with normal PSV les likely any stenosis.
This has normal PSV with raised RI. need further evaluation like graft biopsy, MRA, to confirm raised RI and rising creatnine.
Peak Systolic Velocity (PSV)= 177 cm/sec – Normal range between 10-210 cm/sec,
Resistive Index (RI)= 0.8 – Normal 0.5-0.75
creatinine rising by 12 μmol/L which is insignificant There is no reversal of flow as you see in the signal above the zero line
.
What is your management plan?
according to the given data conservative management with follow-up.
Reference:
Baxter GM, Ireland H, Moss JG, Harden PN, Junor BJ, Rodger RS, Briggs JD. Colour Doppler ultrasound in renal transplant artery stenosis: which Doppler index? Clin Radiol. 1995 Sep;50(9):618-22. doi: 10.1016/s0009-9260(05)83291-x. PMID: 7554736.
it’s doppler ultrasound of renal artery and vein shows PSV 177 cm-% and RI0.81, so it’s not significant and no evidence of renal artery stenosis and no reversal flow of vein, so it indicates no renal vein thrombosis
Good hydration
Drug level of calcinurine inhibitors
Continuous immunosuppressive therapy
This patient us parameter its acceptable as well as the Rasing in creatine is not signficant.
Most likely patient need hydration and repet the renal profile,if it is return to notmal that mean there is some dehydration.
if it recure again we can did Renogram to asses the perfusion and excreation
The above image is renal artery and vein doppler of the transplant kidney….The peak systolic velocity is 177cm/sec. normal range of PSV is between 150-210 cm/sec…PSV >250cm/sec in the transplant renal artery has a sensitivity of 100% and specificity of 98% for the detection of renal artery stenosis….
Resistive index is defined as Peak systolic velocity – end diastolic velocity/ Peak systolic velocity….Normal RI -0.6 to 0.8…Raised RI more than 0.8 indicated renal vein thrombosis, ATN, pre renal azotaemia and rejection… Low RI indicates renal artery stenosis
RI has been 0.81 in this patient….but this patient has normal creatinine…i will like to monitor the serial renal functions and then decide…
Post-transplant renal vein thrombosis is rare occurring in 0.3% to 4.2% of kidney transplant recipients. The outcome is usually poor because of the lack of collateral circulation with the venous flow originating from the renal vein .
This can not only lead to the loss of the graft itself but may also result in a high mortality rate due to graft rupture and embolic complications.
Successful revascularization with thrombolytic therapy, thrombus-aspiration, or direct surgical thrombectomy have been reported.
Reference
Color Doppler ultrasound diagnosis of intrarenal vein thrombosis
A rare case report and literature review
Yixiu Zhang, MD, Ying Wang, MD, […], and Sheng Cai, MD
Post transplant renal vein thrombosis, with successful thrombectomy and review of the literature
Mark Lerman, Matthew Mulloy, […], and Xin J Zhou
Will you explain the Duplex scan findings?
In this renal transplant recipient there is rise in creatinine by 12 umol/L.
RV seen by Duplex.- No reversal of flow.
PSV is 177 cm/sec
RI is 0.81- Slight elevation.
These findings are essentially normal. There is slight rise in serum creatinine.
What is your management plan?
The scan findings are generally normal and standard current treatment should continue.
Patient should have adequate hydration
Repeat CNI levels
Regular follow up is required.
Kolofousi C, Stefanidis K, Cokkinos DD, Karakitsos D, Antypa E, Piperopoulos P. Ultrasonographic features of kidney transplants and their complications: an imaging review. ISRN Radiol. 2012 Dec 2;2013:480862.
Will you explain the Duplex scan findings?
· Intrarenal arterial spectral tracing shows a normal systolic arterial upstroke without reversal of flow.
· Peak Systolic Velocity(PSV) of 177cm/s is considered to be within normal range of 10-210cm/s.
· Visualization of normal transplant renal vein exclude TRVT.
· RI of 0.81 is high, and may give a clue to; rejection, acute tubular necrosis, urinary tract obstruction in association with back-pressure and hydro-nephrosis. No evidence of urinary tract obstruction or hydro-nephrosis in the index case.
What is your management plan?
· The rise of SCr by 0.13 mg/dl, although insignificant rise may give a clue to early rejection. If SCr continue to rise, graft biopsy is needed.
· Close observation, full support and follow up with repeat to investigations and doppler study are warranty.
Will you explain the Duplex scan findings?
The duplex scan showed:
· A normal visualized renal vein excluding transplant renal vein thrombosis
· The wave form or the renal artery showing:
– peak systolic velocity 177cm/sec (normal 150-180 cm/sec).
– slightly raised resistive index 0.8 (normal 0.6-0.7). RI is a sonographic index of intra-renal arteries defined as (PSV-EDV) / PSV. Raised RI is associated with poor prognosis in various renal disorders and renal transplants.
– Therefore, We need to exclude other causes of raised RI
1) hydronephrosis(absent in this case)
2) Renal vein thrombosis (there is a normal visualized vein)
3) Renal parencyymal disorders like ATN, acute rejection, CNI toxicity, recent use of ACEI or beta blockers
4) Operator dependant
· TRAS is unlikely as it is associated with a high PSV >200cm/s & low RI(<0.55). Also, there is no reversed flow(diastolic flow)
What is your management plan?
· Having excluded major vascular complications by Doppler US, the rise in serum creatinine is not significant(<15%) but should not be ignored
· Therefore, continue same management plan and ensure adequate hydration.
· follow up of the serum creatinine level, CNI levels and proteinuria
References:
Sharfuddin A. Renal relevant radiology: imaging in kidney transplantation. Clin J Am Soc Nephrol. 2014 Feb;9(2):416-29.
The renal vein is seen in the image. There is no reversal of flow. The patient has a low rise in creatinine and PSV is less than 200 in this scan. Thus renal artery stenosis is not likely.
There is no evidence of hydronephrosis.
This appears to be a normal doppler, and thus we do nothing. Monitoring and repeating creatinine levels might be considered.
PSV normal range.
RI slightly raised.
Plan
Observation and follow up
Explain the Duplex scan findings?
A- Normal visualized renal vein
B-Renal Artery :
PSV 177 cm/ sec ( Normal )
Not significant important until if high (> 250 cm/s) higher velocities predict significant stenosis with high sensitivity and specificity .
RI 0.8 is considered to be slightly high ( Normal 0.5: 0.7 )
But not associated with significant rise of kidney functions
Causes of high RI :
acute and chronic rejection
obstruction of urinary track accompanied with hydronephrosis
ATN
Renal artery and vein thrombosis
What is your management plan?
No significant rise of kidney functions just for close follow up of the patient
Exclusion of the following
Transplanted renal artery stenosis >> normal PSV
No Renal artery thrombosis >> Normal follow pattern
No Renal vein thrombosis >> presence of the venous color flow
Ref :
Brown ED, Chen MY, Wolfman NT, Ott DJ, Watson NE., Jr Complications of renal transplantation: evaluation with US and radionuclide imaging. Radiographics. 2000;20:607–622.
Lockhart ME, Robbin ML. Renal vascular imaging: ultrasound and other modalities. Ultrasound Q. 2007;23:279–292. doi: 10.1097/ruq.0b013e31815adf4c.
Will you explain the Duplex scan findings?
• What is your management plan?
PSV 177 cm/ sec
EDV 33 cm/ sec
RI 0.81
Color Doppler US is considered the first-line imaging modality to evaluate graft dysfunction because of its portability, rapid technique, and lack of radiation or toxic dye. It also provides some physiologic information about the allograft. The healthy allograft appearance is similar to that of the native kidneys, although clearer detail is usually apparent because of its superficial anatomic location.
As a result of the new anastomosis at the uretero-vesical valve junction, high-urine-output state, and mild anastomotic edema, the collecting system of a well functioning allograft is often slightly dilated in the immediate and early postoperative period.
The vessels of the healthy transplant, through positioning of the graft in the iliac fossa, may appear as tortuous vessels on imaging that may pose a difficulty in assessing peak velocity measurements, as discussed below in evaluating for transplant renal artery stenosis. The renal arterial resistance index (RI) is a sonographic index calculated as follows:
The renal artery vessels normally demonstrate a low-resistance waveform with an RI<0.7. The normal peak velocity of the transplant renal artery is in the range of 170–210 cm/sec, whereas the renal venous flow is flat with low-velocity waveforms
Along with renal artery measurements, the proximal and distal iliac vessels also need to be evaluated to compare the flow to the renal artery velocities. Elevated renal artery velocities in the immediate postoperative period do not necessarily represent stenosis requiring intervention because in most cases they normalize over time
Reference
Renal Relevant Radiology: Imaging in Kidney Transplantation
Asif Sharfuddin
Copyright © 2014 by the American Society of Nephrology. http://www.cjasn.org Vol 9 February, 2014
The index transplant recipient presented with a serum creatinine increase of 12 μmol/L. Duplex scan was performed on the transplant kidney which showed:
1) PSV of 177 cm/s. The normal value of PSV is in range of 170-210 cm/s (1,2).
2) RI is slightly elevated (> 0.8) as the normal values are in range of 0.65+0.17 (3).
3) The renal vein is visualized and there is no reversal of flow.
Overall the findings are within normal limits, reassuring especially in presence of an insignificant increase of serum creatinine.
As the Doppler findings are normal, and the rise in creatinine is not significant, the current treatment should be continued without any deviation. Still the patient can be kept under follow-up, by repeating the serum creatinine level and CNI levels.
References:
1) Sharfuddin A. Renal relevant radiology: imaging in kidney transplantation. Clin J Am Soc Nephrol. 2014 Feb;9(2):416-29. doi: 10.2215/CJN.02960313. Epub 2013 Nov 7. PMID: 24202132; PMCID: PMC3913229.
2) Park BK. Gray-Scale, Color Doppler, Spectral Doppler, and Contrast-Enhanced Renal Artery Ultrasound: Imaging Techniques and Features. J Clin Med. 2022 Jul 7;11(14):3961. doi: 10.3390/jcm11143961. PMID: 35887726; PMCID: PMC9318477.
3) Granata A, Fiorini F, Andrulli S, Logias F, Gallieni M, Romano G, Sicurezza E, Fiore CE. Doppler ultrasound and renal artery stenosis: An overview. J Ultrasound. 2009 Dec;12(4):133-43. doi: 10.1016/j.jus.2009.09.006. Epub 2009 Oct 12. PMID: 23397022; PMCID: PMC3567456.
The normal PSV of the main renal artery is around 80-200 cm/sec
Renal artery stenosis is suspected when PSV is more than 200 cm/sec.
Reversed flow can not happen with this P
The rise in serum creatinine level is not significant, it should be more than 25.6 micromol/L
it should be normal doppler
-The PSV threshold for defining hemodynamically significant stenosis is variable , but a value of 250 cm/s is still within the normal range, whereas higher velocities predict significant stenosis with high sensitivity and specificity, in this case it is 177cm/s
The recipient’s iliac vessels must be examined by pretransplant color Doppler exploration. Narrowing of arterial vessels within the graft has been reported, but it is difficult to visualize with CDUS or withangiography.
The resistive index (RI) is used as a measurement of resistance to arterial flow within the renal vascular bed. An RI of less than 0.7 to 0.8 is considered normal and if the RI exceeds 0.8, it is an indicator of transplant dysfunction.
A low RI within the graft, less than 0.6, may be highly specific for stenosis over 50%. Reduction in pulse amplitude and delayed systolic upstroke with an acceleration index less than 3 m/sec or a systolic acceleration time over 0.07 sec is considered strong evidence of severe RAS.
In this case RI 0.8 after transplantation is acceptable but needs further follow up.
The creatinine rise of 12 umol(0.14 mg/dl) is insignificant ,but patient follow up is needed
Reference
-Granata A, Clementi S, Londrino F, Romano G, Veroux M, Fiorini F, Fatuzzo P. Renal transplant vascular complications: the role of Doppler ultrasound. J Ultrasound. 2014 Apr 11;18(2):101-7.
– Al-Khulaifat S. Evaluation of a Transplanted Kidney by Doppler Ultrasound. Saudi J Kidney Dis Transpl 2008;19:730-6
PSV is with in normal range
RI and S. Creatinine slightly raised
Plan of management: observation
Will you explain the Duplex scan findings?
Peak Systolic Velocity (PSV)= 177 cm/sec – Normal range between 150-210 cm/sec, PSV equal or > 250 cm/sec in the transplant renal artery had a sensitivity of 100% and a specificity of 95% for the detection of renal artery stenosis.
Resistive Index (RI)= 0.8 – Normal 0.5-0.75, high RI > 0.8 (indicates : renal vein thrombosis, ATN, prerenal azotemia, and rejection) is the strongest predictor of long-term allograft failure and death.
RI equal or less than 0.5 indicates transplant renal artery stenosis.
What is your management plan?
Given the all data mentioned above, conservative management is warranted, with full history and careful clinical examination. Nothing more.
Reference:
Baxter GM, Ireland H, Moss JG, Harden PN, Junor BJ, Rodger RS, Briggs JD. Colour Doppler ultrasound in renal transplant artery stenosis: which Doppler index? Clin Radiol. 1995 Sep;50(9):618-22. doi: 10.1016/s0009-9260(05)83291-x. PMID: 7554736.
_ The interpretation of this duplex scan:
1. peak systolic velocity (PSV) must be lower than 180 cm/sec, if more than 180 it means renal artery stenosis.
2. The resistive index (RI) must be lower than 0.8 and if it is elevated it means renal vein thrombosis (together with reversal of diastolic wave, to be drwan as negative wave below the zero line).
_ so the current duplex shows PSV 177 and RI of 0.8 which are normal values, together with systolic and diastolic waves in the normal directions, both above the zero line (no reversal of flow), so it is suggestive of normal duplex study.
_ the current rising of creatinine is equivalent to 0.13 mg/dl which is not significant, hence nothing to be done.
_ however, follow up if the serum creatinine (it’s rise more than 20 % of the basal craetinine, it indicates allograft biopsy).
Thanks prof .Halawa so its normal doppler.
as RI is only 0.8.
PSV within normal 177cm/sec.
Diagnose TRAS :
Acceleration time in the transplant renal and intrarenal arteries ≥0.1 s,
PSV >200 cm/s and
a ratio of peak systolic velocity in the transplant renal-to-external iliac arteries >1.8 .
Elevated peak systolic velocity in the transplant renal artery is the most sensitive
Doppler criterion for the detection of high-grade TRAS .
TRVS:
Duplex ultrasonography characteristically reveals reversed arterial diastolic flow (i e, the
arterial waveform positive during systole and negative during diastole), a spike like
systolic component, and non visualization of the renal vein.
References:
1- Wei Chen et al Transplant renal artery stenosis: clinical manifestations, diagnosis and
therapy. Clin Kidney J. 2015 Feb; 8(1): 71–78.
Will you explain the Duplex scan findings?
-The peak systolic velocity (PSV) in the main renal artery, normal values are 60-100 cm/s .
-The resistive index (RI) can be determined by dividing the difference between the PSV and end-diastolic velocity by the PSV (normal range is 0.5 to 0.7).
-In this case, there is a mild increase in RI(0.81)
-Renal artery stenosis (RAS) is the most common vascular complication in renal transplants. Doppler US criteria for RAS can be split into direct and indirect signs. Direct signs are seen at the site of the stenosis and include the following criteria: A PSV > 200 cm/s (compatible with ≥ 60% stenosis), increased renal/aortic PSV ratio (>3.5:1), absence of Doppler US signal consistent with occlusion, and aliasing with post-stenotic turbulent flow/spectral broadening. Indirect downstream effects can be observed distal to the stenosis site and are especially important in renal artery US imaging since the stenosis site itself might be not well seen; specifically, a “parvus-tardus” waveform (blunted and delayed systolic upstroke), which will be most evident in the peripheral renal vasculature. This corresponds to an AI < 3 m/s, an AT > 70 msec and a decreased RI < 0.5.
–this US normal.
What is your management plan?
No need for management.
Reference:
Lukas M. Trunz; Rashmi Balasubramanya. Doppler Renal Assessment, Protocols, And Interpretation.National library of medicine.
Renal transplant recipient who has a rise of his S Cr by 12 μmol/L. The renal vein is visualized by the duplex scan. The transplant artery signals are shown below.
Early (Acute Graft Dysfunction )
Timimg
1- in the first few days
2- in the first 3 months
3- more than 3 months .
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Will you explain the Duplex scan findings?
PSV in a Doppler ultrasound
D.D:-
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What is your management plan?
plan mangement depended underlying causes.
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Refernce
To interpret the information given one has to know the basic principle which is as follows.
1) Peak systolic velocity (PSV) must be measured in the abdominal aorta at the renal artery level and the renal artery origin, middle portion, and helium. The normal range is 60-100 cm/s
2) The PSV renal artery and the PSV of the aorta have a ratio of less than 3.5
3) Intrarenal arteries include acceleration time (AT) the time of the start of systole to peak systole less than 70 msec normal.
4) Acceleration index (AI) the slope of the systolic upstroke is greater than 3 m/s is normal.
5) Resistive index (RI) is determined by dividing the differences between the PSV and end-diastolic velocity by the PSV normal range is 0,5-0.7
From the diagram, the patient’s PSV IS 177cm/s. EDV is 33.0 cm/s and RI 0.81
So from this one can see that the RI is slightly elevated which is interpreted as elevated pressure intrarenal or it can be a miss calculation of the ultrasonographer. So there is no renal stenosis due to the fact that the RI would have been less than 0.5. if the PSV was greater than 200 cm/s it would have inclined to renal artery stenosis. If there was a delay in the systolic upstroke with a parvus- tardus waveform, then it would give details of stenosis and the AI less than 3 m/s, AT greater than 70msec, and decrease RI less than 0.5
The result;t of the Doppler is likely normal and as such only close monitoring is needed. However, if there was blood pressure elevated despite treatment and having difficulty controlling them another cause has to eliminate.
References”
Trunz. M., L. and Balasubramanya, R., (2022). Doppler renal assessment, protocol and interpretation.
Thank you
I can see the RI can see a peak systolic volume of 177, which is near normal (<180), and RI increased (>0.7). I could not see turbulence. In the context of Renal transplantation, higher RI, which is not too high here in parallel with an increase of serum creatinine (when more prominent), will draw attention to increased pressure in renal circulation and the probability of rejection. so may need DSA evaluation and biopsy when needed
Thank you
The normal range for RI is 0.50-0.70.
The normal range for PSV 150-180 cm/sec
The normal range for EDV is 20 – 50cm/sec.
Restrictive Index:
RI is a sonographic index of intrarenal arteries defined as (PSV-EDV) / PSV.
It is a nonspecific prognostic marker
Elevated values are associated with poorer prognosis in various renal disorders and renal transplants.
Reasons for elevated values in a transplanted kidney
ATN
Rejection of acute or chronic
Renal vein thrombosis.
Drug toxicity
Ureteric obstruction
Perinephric fluid collection.
Reasons for decreased values
Renal artery stenosis.
Reverse diastolic flow;
Reversed or absent diastolic flow is a sign of highly vascular resistance in small intrarenal or large extrarenal vessels.
Retrograde blood flow occurred at any time point during the diastole, regardless of whether antegrade flow had happened.
A finding of isolated reversed or absent diastolic arterial flow is sensitive and not pathognomonic and nonspecific to TRVT and may also be seen in other causes.
The finding in the index case showed:
PSV 177 cm/ sec
EDV 33 cm/ sec
RI 0.81
Doppler US finding with Increased intrarenal artery RI and a decrease in the PSV in the first 1-3 months post-transplantation can still be a normal variant in the early post-transplant period.
There is no reverse in diastolic flow. ( only positive deflection seen mean flow in the renal artery, no negative deflection ) therefore, RAS is less likely the general finding suggestive of RAS:
increased PSV > 180 cm/s
Turbulent flow in a post-stenotic area
Tardus Parvus waveform (slow-rising) due to stenosis
Decreased RI <0.55 in severe stenosis
RI difference between kidneys >5% 9
The image needs to be repeated later on and consider the following; Patient has slightly elevated creatinine but not AKI by definition; with sight increase in RI we need to look for:
Volume status and cardiac output.
CNI level.
Any evidence of infection.
DSA level
References:
-Sharfuddin A. Renal relevant radiology: imaging in kidney transplantation. Clinical Journal of the American Society of Nephrology. 2014 Feb 7;9(2):416-29.
– El Zorkany K, Bridson JM, Sharma A, Halawa A. Transplant Renal Vein Thrombosis. Exp Clin Transplant. 2017 Apr;15(2):123-129. doi: 10.6002/ect.2016.0060. PMID: 28338457.
Thank you
Dear colleagues,
I refer you to this article:
Sharma AK, Rustom R, Evans A, Donnolly D, Brown MW, Bakran A, Sells RA, Hammad A. Utility of serial doppler ultrasound scans in diagnosis of acute rejections in renal allografts. Transplantation International 2004; 50: 189-93.
Abstract….
This study aims to explore the utility of serial duplex scanning and to compare its results with those of single time-point scans of renal allografts in the diagnosis of acute rejection (AR). A retrospective analysis of 6017 serial duplex scans (mean: 9.8 scans per patient, 5.7 of which were done during the first 10 days) was performed in 614 patients with 462 episodes of AR from 1992-2000. Even in the absence of AR (n=278), there were day-to-day fluctuations in pulsatility index (PI) and resistive index (RI). An increase of >10% in intra-renal indices was noted 0.95 days (mean) before the commencement of treatment for AR (SD 1.3, range 1-6 days). In patients with acute tubular necrosis (ATN), who have high base line indices, sensitivity of single value of PI and RI was 58% (cut-off level 1.8) and 68% (cut-off level 0.8), with specificity of 66% and 56%, respectively. By contrast, a >10% increase over the previous ‘best’ in PI and RI had a sensitivity of 78% and 60% respectively, and a specificity of 78% and 90%, respectively. Reversal of flow during diastole (n=50) was found to be associated with 22% graft loss within 3 months of transplantation. We can conclude that a considerable overlap between the indices of patients with AR and those with ATN greatly limits the diagnostic yield of duplex scanning. Nonetheless, serial scanning of renal allografts is more likely to herald the need for biopsy in the diagnosis of AR than one-time scanning.
Thank you prof
Thank you prof Sharma
The PSV in normal renal arteries ranges from 74 to 127 cm/s in adults and is slightly higher in children and young adults.
From a hemodynamic perspective, renal artery obstruction is considered hemodynamically significant (or flow reducing) when the luminal diameter is narrowed by 50% to 60%.
Vascular resistance (impedance) is measured as the percent reduction of the end-diastolic flow compared with the systolic flow. The RI is calculated as peak systolic velocity (PSV) minus end-diastolic velocity (EDV) divided by PSV, and the PI is calculated as the PSV minus EDV divided by the mean velocity.
These two parameters are often elevated in rejection however, elevated RIs and PIs can be seen in any cause of renal dysfunction and are nonspecific
the renal transplant RI is a valuable predictor of long-term allograft performance; a RI of 0.8 or greater at 3 months after transplantation has been reported to
be associated with poor subsequent allograft function.
In this scinario, PSV177 still within the normal range+ risening of creatinin is not significant
So, Re evaluate if the patient develop the patient any of:
*severe or abrupt onset of hypertension,
*refractory hypertension that is difficult to control despite a suitable treatment
*any deteriorating renal function
References;
Handbook of
Kidney
Transplantation
Edited by
Gabriel M. Danovitch, MD
Medical Director, Kidney and Pancreas Transplant Program
Ronald Reagan Medical Center at UCLA
John J. Kuiper Chair of Nephrology and Renal Transplantation
Distinguished Professor of Medicine
David Geffen School of Medicine at UCLA
Los Angeles, California
https://radiologykey.com/duplex-ultrasound-of-native-renal-vasculature/
Hi Dr Mohammed,
This is not renal artery stenosis.
Will you explain the Duplex scan findings?
with this picture alone and its limited history it’s difficult to give a definite diagnosis we need to know the duration of the transplant and blood pressure of the patient,, any proteinuria, baseline creatinine, the age of both donor and recipient, details about the surgery, and the vascular anastomosis type however this image of the doppler US with borderline RI 0.81 and PSV < 250 less likely to be associated with significant RAS and need to rule out other causes of acute graft dysfunction with high RI like ATN, acute rejection, obstruction, CNI toxicity, recent use of ACEI or BB
1. Doppler US finding with Increased intrarenal artery RI of 0.81 and a decrease in the PSV in the first 1-3 months post-transplantation can still be seen with normal graft function.
2. Transplant renal artery stenosis: TRA stenosis (TRAS) is the most common vascular complication post-KT, and accounts for 75 % of all vascular complications. It is usually detected 3–24 months after transplantation but can occur at any time the incidence is quite varied but it’s in the range of 1-23%
Color Doppler ultrasound criteria for the diagnosis of TRAS
1. acceleration time (a t) in the transplant renal and intrarenal arteries ≥0.1 s,
2. peak systolic velocity in the transplant renal artery >200 cm/s and a ratio of peak systolic velocity in the transplant renal-to-external iliac arteries >1.8 1
3. focal PSV of 180–200 cm/s may be suggestive of significant TRAS
4.. Spectral analysis shows a ‘‘tardus-Parvus’’ waveform at the level of the arcuate artery and a definite diagnosis of TRAS by angiogram vs MRI.
3. Visualized renal vein rules out TRVT, TRVT is rare only in 4% but if it happened it will end up with a graft lost the two most important CDUS findings for the diagnosis of TRVT are the absence of the venous color signal (reflecting the absence of vascularization), and the reverse diastolic flow within the renal artery
4. Transplant renal artery thrombosis (TRAT) again is rare and can be catastrophic in immediate post-TX complication
The sensitivity and specificity of CDUS in the diagnosis of renal artery thrombosis are close to 100 %, in complete renal artery occlusion, there will be no arterial flow and the complete absence of venous flow wave while segmental arterials occlusion will be characterized by the absence of arteriovenous flow only in the affected segment.
What is your management plan?
borderline RI 0.81 and PSV < 250 is less likely to be associated with RAS and needs to rule out other causes of acute graft dysfunction with high RI like acute rejection, obstruction, CNI toxicity many independent factors associated with higher intrarenal RI like recipient age> 40 years (older recipients have higher RI), male donor status, higher pulse pressure, lower Mean pressure, and use of BB and diuretics, ACEI.
CNI trough level, proteinuria level, urine culture
References
1.Isiklar I, Aktas A, Akgun S, Karakayali H. From donor to recipient. Doppler US, power US and scintigraphy of kidney perfusion before and after transplantation. Acta Radiol. 2000 May;41(3):285-7.
2.Como G, Da Re J, Adani GL, Zuiani C, Girometti R. Role for contrast-enhanced ultrasound in assessing complications after kidney transplant. World J Radiol. 2020 Aug 28;12(8):156-171
3.Naesens M, Heylen L, Lerut E, Claes K, De Wever L, Claus F, Oyen R, Kuypers D, Evenepoel P, Bammens B, Sprangers B, Meijers B, Pirenne J, Monbaliu D, de Jonge H, Metalidis C, De Vusser K, Vanrenterghem Y. Intrarenal resistive index after renal transplantation. N Engl J Med. 2013;369:1797–1806
4. Radermacher J, Mengel M, Ellis S, Stuht S, Hiss M, Schwarz A, et al.. The renal arterial resistance index and renal allograft survival. N Engl J Med 2003; 349: 115–24.
5.Mutinelli-Szymanski P, Caille A, Tranquart F, Al-Najjar A, Büchler M, Barbet C, et al.. Renal resistive index as a new independent risk factor for new-onset diabetes mellitus after kidney transplantation. Transpl Int 2012; 25: 464–70. doi: 10.1111/j.1432-2277.2012.01445
6.Granata A, Clementi S, Londrino F, Romano G, Veroux M, Fiorini F, Fatuzzo P. Renal transplant vascular complications: the role of Doppler ultrasound. J Ultrasound. 2014 Apr 11;18(2):101-7
7.chen W, Kayler LK, Zand MS, Muttana R, Chernyak V, DeBoccardo GO. Transplant renal artery stenosis: clinical manifestations, diagnosis and therapy. Clin Kidney J. 2015 Feb;8(1):71-8.
I like your plan, Dr Saja.
What do you expect the normal PSV to be?
The normal peak velocity of the transplant renal artery is in the range of 170–210 cm/sec.
So, the PSV in this image is in normal range
Can we have renal artery stenosis with this PSV?
Absolute PSV is less meaningful. The ratio of PSV in graft renal artery and recipient artery is important.
Doppler criteria for significant stenoses include the following:
Can we have a reversal of flow with this PSV and this RI?
Reversal of flow is indication of severe resistance to flow (ie no diastolic flow)
RI in this image is 0.81
Normal RI is 0.5 to 0.7
Raised RI is suggestive of
In this case, there is no hydronephrosis and renal vein is patent, so most probable cause would be parenchymal disorder
Do you think the rise of creatinine is significant?
A rise of creatinine by S Cr by 12 μmol/L can be monitored. A rise in creatinine by 25%, would warrant graft biopsy in this case to rule out parenchymal disorder.
Sharfuddin A. Renal relevant radiology: imaging in kidney transplantation. Clinical Journal of the American Society of Nephrology. 2014 Feb 7;9(2):416-29.
Thank you, Excellent answer and justification
PSV= 177
EDV= 33
RI= 0.8
the normal peak systolic velocity (PSV) of the main renal artery is less than 80 – 150 cm/sec, while the end-diastolic velocity (EDV) is 20 – 50cm/sec.
I need to know the time post-transplant as these findings can happen in the early post-transplant period. the rise in serum creatinine level is not significant ( less than 30 umol/L) although no baseline serum creatinine level is given.
This patient needs follow-up.
Reference:
https://ultrasoundpaedia.com.
I like your plan, Dr Huda.
thank you Prof Sharma
Duplex scan findings:
The peak systolic velocity is 177cm/sec with a resistive index is 0.81
The normal peak velocity of the renal transplant artery is between 170-201 cm/sec. So this is normal peak velocity and rules out renal artery stenosis
The resistive index is normally less than 0.7. The resistive index for this patient is 0.81 which is on the higher side.
A high RI can be seen in:
Management Plan
The patients serum creatinine has increased by 12 mmol/L. This does not fit the criteria for AKI as per the KIN criteria which requires an increase of 0.3 mg/dL or 26.4 mmol/L. The increase in serum creatinine should not be ignored. We also need to take a clinical history and assess if he has
He will need to have the CNI levels checked and have a urinalysis done to assess for proteinuria.
He should be advised to increase his fluid intake and the creatinine rechecked in a few days
If the CNI levels are high, then the dose needs to be adjusted
CJASN February 2014, 9 (2) 416-429
Thank you, Excellent answer and justification
The finding of the above Duplex scan:
The waveform of the renal artery;
The normal Doppler US finding of the renal artery;
Diagnosis;
This patient have normal variation, although some advocate PSV > 180 may indicate Renal artery stenosis ., also the RI index is high 0.81.
The some elevation of PSV and RI may be correlated with the first transplant period .
The raise of S.Cr is not that even indicate AKI, but workup is vital to detect any ongoing abnormality specially if Cr is rising.
Refferences;
Ultrasounopaedia .com.
Thank you, Excellent answer and justification