Does Contrast-Enhanced Ultrasound Positively Influence Selection of Biopsy Sites When Evaluating Transplant Kidneys?
Phase: PHASE4
Conditions: Transplantation, Kidney
Sponsor: Mayo Clinic

 
 
Does Contrast-Enhanced 
Ultrasound Positively Influence 
Selection of Biopsy Sites when 
Evaluating Transplant Kidneys? 
 
NCT02625428 
 
26 November 2014 

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Does Contrast-Enhanced Ultrasound Positively Influence Selection of Biopsy 
Sites when Evaluating Transplant Kidneys? 
Protocol Date: 26 November 2014 
J. Scott Kriegshauser, MD1, Co-principal Investigator 
Nirvikar Dahiya, MD1, Co-principal Investigator  
Maxwell Smith, MD2 
Ray Heilman, MD3 
Maitray Patel, MD1 
Scott Young, MD1 
M’hamed Temkit4 
 
Introduction 
Histopathological changes in kidney allograft are not always homogeneous. [1] Common 
pathologic abnormalities found on biopsy of transplanted organs, including renal transplants, can 
be patchy in distribution, especially in rejection and chronic nephropathy.  [2-6]] This may result 
in a suboptimal sample when performing a random transplant renal biopsy. [4, 6] Strategies to 
minimize sampling error include using larger needles or obtaining additional cores, since 
complications of biopsy remain very low and the benefit far exceeds the risk. [4, 6, 7] We 
hypothesize that contrast-enhanced ultrasound (CEUS) may help evaluate segmental differences 
in renal perfusion better than Doppler Ultrasound and thus help direct the biopsy to the most 
abnormal part of the renal cortex. This should maximize detection and increase the odds of 
demonstrating the true grade/severity of the histopathological abnormality. 
CEUS has been FDA approved for echocardiography but its use elsewhere in the body is 
considered off-label. It has been used extensively outside the United States within the abdomen, 
but most commonly for liver masses. CEUS investigations within transplant kidneys have shown 
additional information can be obtained when compared to gray-scale and Doppler ultrasound. 
Apart from a better estimate of parenchymal perfusion it allows for evaluation of graft vascular 
kinetics, including quantitative measurements, e.g. time-to-peak enhancement (TTP) within the 
cortex or pyramids. [8-14] Studies have also shown CEUS is more sensitive to renal perfusion 
defects than Tc-DTPA. [15] This ability of CEUS to evaluate perfusion over time may help 
target renal transplant biopsies to the most abnormal segments.  
Hypothesis/Expected Results 
CEUS targeted biopsies to areas of decreased or inhomogeneous perfusion will show disease 
processes significantly more often or of a higher severity than (non-targeted) random biopsies. 
Additionally, this directed biopsy may demonstrate more significant or advanced disease, as 
measured by Banff criteria, when compared to a routine non-targeted biopsy.  Random biopsies 

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of different segments in the same kidney, when no focal or segmental CEUS abnormality is 
demonstrated, will not be significantly discordant for disease or Banff criteria. 
Proposed investigation 
IRB approval from our institution will be obtained for this pilot study of 40 consecutive 
consenting male and female adult patients over 18 years of age undergoing renal transplant 
ultrasound-guided percutaneous biopsy within 24 months post-transplant, including patients 
undergoing biopsy to evaluate a recent rise in serum creatinine, so-called for cause biopsies and 
patients undergoing routine protocol (surveillance) biopsies without other evidence of renal 
dysfunction. Pregnant patients will be excluded. The routine protocol biopsies are done at 4 
months and 1 year after transplant mostly looking for subclinical rejection. Informed written 
consent (IRB approved consent form) will be obtained from all patients prior to the scan and 
biopsy procedure. This will include consent for the off-label use of Optison and the need to 
obtain 2 or 3 biopsies specimens, when routinely only 1 or 2 are obtained. All patients will meet 
our standard anticoagulation guidelines for undergoing renal transplant biopsy.  
CEUS will be performed in addition to our routine color-Doppler ultrasound evaluation of the 
transplant kidney prior to the biopsy. One vial (3.0 mL) of Optison will be utilized for each 
patient, with expected doses to be in the range of 1-1.5 mL for each scan sequence, allowing up 
to 2 to 3 scan sequences per patient exam. Low mechanical index settings and coded harmonics 
will be utilized. Each scan sequence will be recorded for up to 5 minutes. Post-processing will be 
performed using an off-line workstation if needed. 
 All patients will have at least 2 core biopsies of their transplant kidney under ultrasound 
guidance, using the cortical tangential approach whenever possible. [7]  One core will be 
obtained from the most easily accessible location, usually the upper pole, without consideration 
of CEUS results (labeled “random #”, with “#” the ordinal number of the biopsy).  A second core 
biopsy will be obtained from a segment that demonstrates variable CEUS perfusion. This sample 
will be labeled “targeted #”.  If no abnormality is detected with CEUS, a second biopsy will still 
be performed in a distinctly separate location from the first (labeled “random #”).  Conceivably, 
there could be additional biopsies added to the same “targeted #” or “random #” container if the 
previous biopsy in that region is/are not satisfactory or inadequate for any reason and obtained 
from the same general region of the kidney. We will be targeting areas of low perfusion. Many 
studies have shown CEUS using “global” cortical perfusion analysis can significantly aid 
detection of rejection (and other processes, e.g. chronic allograft nephropathy). [8, 9, 12, 14, 
16]In pigs, CEUS is very good at detecting focal perfusion abnormalities. [15, 17] CEUS is 
better at evaluating the cortical perfusion, and not limited to segmental and interlobar artery 
evaluations, as with standard color-Doppler evaluations.  Areas of no perfusion representing 
cortical infarcts would not contribute to the diagnosis and will not be targeted. The perfusion 
characteristics of each site based on CEUS findings will be recorded. Each will also be 
categorized as “For Cause” or “Surveillance”. 

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 The order in which the randomized and targeted biopsies are performed will be randomized. 
Biopsies specimens sent for analysis will be labeled in order only as #1 and #2, blinded to the 
pathologists, with the full description (including “targeted” or “random” with the #) recorded by 
the performing radiologist prospectively. Each biopsy core will be evaluated separately by the 
pathologists. Pathologists will be as definitive as possible in making a diagnosis and specifying 
Banff scores for each individual biopsy core. Differences in pathology will then be reviewed and 
recorded as to presence of disease and differences in Banff scores.  
Safety and Adverse Events 
It is standard practice that patients be kept for observation 1 hour post biopsy and called by the 
nurse at 24 hours. Those patients participating in the study will also be called 72 hours post 
procedure. Any complications or adverse effects occurring within 1 week of the procedure will 
be recorded. 
When an adverse event has been identified, the study team will take appropriate action necessary 
to protect the study participant and then complete the Study Adverse event Worksheet and log. 
The investigator will evaluate the event and determine the necessary follow-up and reporting 
required. 
The investigator will report to the Mayo IRB any UPIRTSOs and Non-UPIRTSOs according to 
the Mayo IRB Policy and Procedures. 
 
Data Handling and Statistical Analysis 
All data will be entered into a secure database and anonymized.  The statistician will create 
REDCap electronic data forms. Statistical analysis will be performed by our statistician after data 
has been obtained for all 40 patients. Detection rates would be compared by using the McNemar 
test. Based on our last 50 renal transplant biopsies, 84% were “surveillance” and 16% were “For 
Cause”. Positive rejection rates have been reported at 12-61% (1 month survey at MCA = 16% 
rejection) for the surveillance group [18-20] and 25-46% (1 month survey at MCA= 25% 
rejection) for the For Cause group.  [20, 21] Using 12% and 25% as the baseline rate of rejection 
detected for Protocol and For Cause biopsies, respectively, we expect 17% of random biopsies to 
be positive for rejection (0.25*0.16 + 0.16*0.84 = 0.17). Conservatively, assuming a 10% false 
negative rate by CEUS biopsy, a sample of 40 patients has 80% power (alpha .05) if detection 
increases by 20 percentage points from 17% to 37%. 
 
Ethical Considerations 

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This study is to be conducted according to United States government regulations and 
Institutional research policies and procedures. The investigator will ensure that the basic 
principles of “Good Clinical Practice,” as outlined in Title 21 of Code of Federal Regulations 
(CFR), Part 50, “Protection of Human Subjects”; 21 CFR, part 54, “Financial Disclosure by 
Clinical Investigators”; 21 CFR, part 56, “Institutional Review Boards”; and 21 CFR, Part 11, 
“Electronic Records, Electronic Signature,” are adhered to. 
This protocol and any amendments will be submitted to a properly constituted local Institutional 
Review Board (IRB), in agreement with local legal prescriptions, for formal approval of the 
study. The decision of the IRB concerning the conduct of the study will be made in writing to the 
investigator before commencement of this study. 
All subjects for this study will be provided a consent form describing this study and providing 
sufficient information for subjects to make an informed decision about their participation in this 
study. This consent form will be submitted with the protocol for review and approval by the IRB 
for the study. The formal consent of a subject, using the approved IRB consent form, must be 
obtained before that subject undergoes any study procedure. The consent form must be signed by 
the subject and the individual obtaining consent. 
 
Expected Deliverables 
Expected time-frame, once funded, for patient recruitment and completion of procedures is 6 
months, and for all deliverables is 1 year. At least 1 scientific paper or poster will be submitted 
for presentation at a major radiology meeting (e.g. RSNA, ARRS, or SIR annual meetings) and 
we will submit a paper for publication in a radiology or medical journal (e.g. Radiology, AJR, or 
JVIR.)  All (anonymized) data will be sent to GE. Depending on results, this may serve as a 
nidus for a larger study. 
Support Requested from GE 
Provide forty vials of ultrasound contrast media (Optison). Provide post-processing 
quantification software for CEUS ultrasound data. Additional pathology costs, due to one 
additional sample for each of the 40 patients.  Ten days (approximately 4% FTE) of paid 
radiologist “Categorical” research time.  10 hours of technologist time.  Cost of statistical 
analysis. IRB and other fees. 
 
1Department of Radiology, Ultrasound Section; 2Department of Pathology; 3Department of 
Nephrology; 4Department of Biostatistics; Mayo Clinic Arizona 
 

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