Renal transplant vascular complications: the role of Doppler ultrasound

Renal transplant ultrasound: assessment of complications and advanced applications

Renal transplantation is the most commonly performed solid organ transplant procedure. Monitoring renal transplants with ultrasound is a critical component in the management of transplant patients both in the immediate aftermath of surgery and longitudinally. Many complications are detectable via ultrasound evaluation with relative prevalence dependent on the time since surgery. It is critical for the practicing radiologist to recognize these complications to help guide appropriate treatment. Fundamental understanding of the procedure, including various surgical techniques is of great importance. In this article, the sonographic findings of the most common postoperative and long-term complications of renal transplantation are reviewed. As complications are highly related to surgical technique, the most common surgical techniques are presented first. Comprehensive ultrasound evaluation of the allograft is discussed next, followed by extensive review of the ultrasound findings of common complications. Finally, select recent advances in ultrasound are presented with their current and potential applications to renal transplant evaluation.

Imaging review of spontaneous renal hemorrhage

Spontaneous renal hemorrhage (SRH) is a diagnostic challenge and a significant cause of morbidity, and sometimes mortality. Early identification is essential to institute lifesaving and reno-protective interventions. In this review, we classify spontaneous renal hemorrhage by location, presentation and etiology. We also discuss the diagnostic approach to renal hemorrhage and optimum imaging modalities to arrive at the diagnosis. Finally, we review strategies to avoid missing a diagnosis of SRH and discuss the pitfalls of imaging in the presence of renal hemorrhage.

Transplant renal artery stenosis: Study of incidence using doppler ultrasound, risk factors and analysis is effect in graft outcomes

INTRODUCTION AND OBJECTIVES

Transplant renal artery stenosis (TRAS) is a vascular complication after kidney transplantation which estimated incidence is 13%. It could cause refractory arterial hypertension, kidney dysfunction and premature death in transplant recipients.

METHODS

We carried out a retrospective study including every patient who underwent renal transplantation between 2014 and 2020. They were evaluated with a systematic post-transplant renal Doppler ultrasound. To identify independent risk factors for transplant renal artery stenosis we performed a multivariate analysis.

RESULTS

Seven hundred twenty-four kidney transplants were included, 12% ​​were living donors and 88% were deceased donors. The mean age was 54.8 in recipients and 53 in donors. Transplant renal artery stenosis was diagnosed in 70 (10%) recipients, the majority in the first 6 months after surgery. 51% of patients with transplant renal artery stenosis were managed conservatively. The multivariate analysis showed diabetes mellitus, graft rejection, arterial resuture and donor body mass index as independent risk factors for transplant renal artery stenosis. Survival of the grafts with transplant renal artery stenosis was 98% at 6 months and 95% at two years.

CONCLUSIONS

The systematic performance of Doppler ultrasound in the immediate post-transplant period diagnosed 10% of transplant renal artery stenosis in our cohort. Despite the above risk factors, an adequate monitoring and treatment could avoid the increased risk of graft loss in patients with transplant renal artery stenosis.

High-Intensity Transient Signals Detected in a Renal Allograft

High-intensity transient signals (HITS) are signals recorded by the Doppler ultrasounds, reflecting either the passage of microemboli, both solid or gaseous in the vessels, or artifacts. Their identification during Duplex US highlights the need for further evaluation to rule out a potential embolic source. A 49-year-old female was referred to our hospital for renal transplantation. The Doppler ultrasound done on day 4 after the surgery revealed the presence of high-intensity transient signals (HITS) suggesting the passage of an emboli. Renal magnetic resonance angiography (MRA) confirmed the presence of peripheral parenchymal defects suggestive of a distal embolus. A better understanding and recognition of this radiological sign are essential in order to initiate appropriate patient management when needed. In this report, we review the importance of HITS and present a case in which HITS were detected in an unusual location: an allograft kidney artery.

Pseudoaneurysm and Renal Artery Stenosis Post-renal Transplant: A Rare Presentation

We report the case of a 51-year-old gentleman who underwent living renal transplantation in Pakistan for end-stage renal disease one and a half years ago. He presented to our hospital with renal artery stenosis and an extra-renal pseudoaneurysm at the anastomotic site of the transplanted kidney. This can cause graft dysfunction and hypertension due to impairment of arterial perfusion in the transplanted kidney. Treatment with percutaneous transluminal angioplasty and covered stenting of the pseudoaneurysm and stenosis improved kidney function and hypertension.

Evaluating the perceptions of Canadian urology residents and program directors regarding the current training in genitourinary imaging

INTRODUCTION

Competency in interpreting genitourinary (GU) imaging is an important skill for urologists; however, no nationally accredited GU imaging curriculum exists for Canadian urology residency training programs. The main objectives of our study were to 1) characterize GU imaging training in Canada; (2) evaluate residents' self-perceived competencies in interpreting GU imaging; (3) explore program directors' (PD) and residents' perceptions regarding the current imaging curriculum and suggestions for future directions.

METHODS

From November to December 2022, a survey examining current imaging education in residency, perceived resident imaging knowledge, avenues for improvement in imaging education, and the role of point-of-care ultrasound within urology was distributed to all Canadian urology PDs and residents.

RESULTS

All PDs (13/13) and 40% (72/178) of residents completed the survey. Only two programs had a formal GU imaging curriculum. PDs and residents reported trainees were least comfortable interpreting Doppler ultrasound of renal, gonadal, and penile vessels. PDs reported that residents were most comfortable with non-contrast computed tomography (CT) scans (9.5/10), CT urogram (9.3/10), and retrograde pyelography (9.3/10). All but one PD favored increasing imaging training in their program. PDs highlighted the lack of time in the curriculum (n=3) and lack of educators (n=3) as the primary barriers to increasing imaging training in their program.

CONCLUSIONS

Most PDs and residents believe there needs to be more imaging training offered at their institution; however, addressing this is challenging due to the limited time in the curriculum and the need for available educators.

A Study Protocol Exploring the Role of an Implantable Doppler Probe in Kidney Transplantation: A Feasibility Randomized Controlled Trial with an Embedded Qualitative Study

OBJECTIVES

Vascular complications in kidney transplant surgery constitute one-third of early graft loss, which can be prevented by timely diagnosis of vascular compromise. A blood flow monitoring device may have a beneficial role in the early identification of graft hypoperfusion critical to reducing graft loss. This research protocol aims to evaluate the potential of an implantable Doppler probe as a blood flow monitoring device in kidney transplant recipients.

MATERIALS AND METHODS

The potential study will be a mixed methodology, 2-arm feasibility randomized controlled trial with an embedded qualitative study. For the trial, we will compare demographic characteristics and outcome measures of kidney transplant patients receiving implantable Doppler probe monitoring (intervention group, n = 30) with those having standard clinical care (control group). For the qualitative study, we will conduct semi-structured interviews with stakeholders (n = 12) recruited by purposive sampling to explore experiences of participants. All interviews will be audio recorded with verbatim transcription.

RESULTS

Our results will use the summarized quantitative data and descriptive statistics to determine differences between the groups. We will use CONSORT guidelines to determine the suitability of the research processes, availability of research resources, and potential challenges faced during the feasibility randomized controlled trial. We will use thematic analysis and NVivo software to analyze the acceptability of the intervention in clinical practice. We will compile the results according to the consolidated criteria for reporting qualitative research checklist.

CONCLUSIONS

The goal of this protocol is to determine the feasibility of an implantable Doppler probe monitoring device in kidney transplant recipients. The feasibility study will collect preliminary information, fill gaps in evidence, and test research processes for the pragmatic future randomized controlled trial. The template of this study is transferable to other transplant centers across the United Kingdom.

Transplant renal artery stenosis: utilization of machine learning to identify ancillary sonographic and doppler parameters to predict stenosis in patients with graft dysfunction

PURPOSE

To determine if ancillary sonographic and Doppler parameters can be used to predict transplant renal artery stenosis in patients with renal graft dysfunction.

MATERIALS AND METHODS

IRB-approved, HIPAA-compliant retrospective study included 80 renal transplant patients who had renal US followed by renal angiogram between January 2018 and December 2019. A consensus read of two radiologists recorded these parameters: peak systolic velocity, persistence of elevated velocity, grayscale narrowing, parvus tardus, delayed systolic upstroke, angle of the systolic peak (SP angle), and aliasing. Univariate analysis using t-test or chi-square was performed to determine differences between patients with and without stenosis. P values under 0.05 were deemed statistically significant. We used machine learning algorithms to determine parameters that could better predict the presence of stenosis. The algorithms included logistic regression, random forest, imbalanced random forest, boosting, and CART. All 80 cases were split between training and testing using stratified sampling using a 75:25 split.

RESULTS

We found a statistically significant difference in grayscale narrowing (p = 0.0010), delayed systolic upstroke (p = 0.0002), SP angle (p = 0.0005), and aliasing (p = 0.0024) between the two groups. No significant difference was found for an elevated peak systolic velocity (p = 0.1684). The imbalanced random forest (IRF) model was selected for improved accuracy, sensitivity, and specificity. Specificity, sensitivity, AUC, and normalized Brier score for the IRF model using all parameters were 73%, 81%, 0.82, and 69 in the training set, and 78%, 58%, 0.78, and 80 in the testing set. VIMP assessment showed that the combination of variables that resulted in the most significant change of the training set performance was that of grayscale narrowing and SP angle.

CONCLUSION

Elevated peak systolic velocity did not discriminate between patients with and without TRAS. Adding ancillary parameters into the machine learning algorithm improved specificity and sensitivity similarly in the training and testing sets. The algorithm identified the combination of lumen narrowing coupled with the angle of the systolic peak as better predictor of TRAS. This model may improve the accuracy of ultrasound for transplant renal artery stenosis.

Value and limitations of sonography in kidney transplant recipients with special attention to the resistive index - An update

Kidney transplantation has become the standard treatment for end-stage renal disease. Even though the success rates are high, early and late post-transplant complications remain a major clinical problem due to the risk of graft failure. Therefore, it is of highest interest to early diagnose post-transplant complications. Ultrasound with color coded Duplex analysis plays a crucial role in imaging mechanical and vascular complications. In this article, we give an update of the visualizable complications in kidney transplant recipients and discuss the value of resistive index (RI) measurement with its limitations in allograft rejection.

Contrast Enhanced Ultrasound Compared with MRI and CT in the Evaluation of Post-Renal Transplant Complications

Renal transplantation (RT) is the treatment of choice for end-stage renal disease, significantly improving patients’ survival and quality of life. However, approximately 3–23% of patients encounter post-operative complications, and radiology plays a major role for their early detection and treatment or follow-up planning. CT and MRI are excellent imaging modalities to evaluate renal transplant post-operative course; nevertheless, they are both associated with a high cost and low accessibility, as well as some contraindications, making them not feasible for all patients. In particular, gadolinium-based contrast can lead to the rare condition of nephrogenic systemic fibrosis, and iodine-based contrast can lead to contrast-induced nephropathy (CIN). CT also exposes the patients who may require multiple examinations to ionizing radiation. Therefore, considering the overall advantages and disadvantages, contrast-enhanced ultrasound (CEUS) is presently considered an effective first-line imaging modality for post-operative early and long-term follow-up in RT, reducing the need for biopsies and providing adequate guidance for drainage procedures. Hence, this paper aims to review the updated knowledge on CEUS compared with CT and MRI for the evaluation of RT renal transplant complications; advantages, limitations, and possible recommendations are provided.

Reversed diastolic flow in a renal transplant due to ureteric obstruction from intraluminal blood clot

Reversal of arterial diastolic flow is commonly considered a sign of transplant renal vein thrombosis until proven otherwise, with the differential including acute rejection, acute tubular necrosis, and perirenal hematoma. We discuss a case of a patient who presented with decreased urine output on the second postoperative day following living unrelated kidney transplantation. Doppler ultrasound was performed and demonstrated reversal of diastolic flow in the transplant renal artery. Prompt surgical exploration revealed intraluminal blood clot obstructing the ureter. To our knowledge, this is the first reported case of reversed diastolic flow secondary to ureteral obstruction by an intraluminal blood clot.

Rescue of an asymptomatic arterial occlusion after kidney transplant

Arterial injury leading to vascular occlusion is a rare complication of kidney transplantation that requires urgent intervention to salvage the kidney and prevent graft loss. Occasionally, the recipient iliac vessels may be injured, resulting in acute ischaemia of the lower extremity in addition to loss of blood flow to the kidney transplant. In the case presented here, a 58-year-old man with chronic kidney disease secondary to IgA nephropathy underwent pre-emptive deceased donor renal transplantation complicated by an external iliac artery (EIA) dissection proximal to the transplant anastomosis. However, as a result of retrograde blood flow from collateral vessels, perfusion of the kidney and right lower extremity was initially preserved and early diagnosis was made after post-transplant ultrasound. This report reviews the aetiology, clinical features and therapeutic options for arterial injuries post-transplant. This case also highlights the importance of post-transplant vigilance and the value of routine postoperative ultrasound imaging.

Renal allograft compartment syndrome: a review

Renal allograft compartment syndrome (RACS) is the result of extrinsic compression resulting in graft dysfunction and loss due to ischaemia. A literature review was performed by computerized searches from the following data sources Medline, EMBASE, PubMed and Cochrane Library databases. Risk factors include size mismatch between graft and recipient. Intraoperative suspicion should be exercised if there is poor tissue turgor, cyanosis and loss of urine output upon fascial closure. Doppler ultrasound is the modality of choice amongst the literature to aid in diagnosis of RACS. From our study, the accepted form of treatment is early detection and appropriate surgical intervention. Nevertheless, it is clear from the paucity of literature that further investigation into this area of transplantation is necessary.

Evaluation of Renal Allograft Vasculature Using Non-contrast 3D Inversion Recovery Balanced Steady-state Free Precession MRA and 2D Quiescent-interval Slice-selective MRA

BACKGROUND AND OBJECTIVES

Renal transplant patients often require periodic imaging to evaluate the transplant vessel anastomosis for potential vascular complications. The use of non-contrast enhanced magnetic resonance angiography (NCE-MRA) techniques is encouraged in these patients because they are at increased risk of nephrogenic systemic fibrosis (NSF) due to their renal insufficiency. This study aimed to evaluate the performance of two NCE-MRA techniques (three-dimensional [3D] balanced steady-state free precession [bSSFP] with inversion recovery and quiescent-interval slice-selective [QISS]) for the evaluation of renal allograft vasculature in patients with clinical suspicion, or Doppler ultrasound, or both of arterial anastomotic stenosis.

METHODS

A total of 43 patients were included in this retrospective study. Two radiologists independently scored the images from 3D bSSFP and QISS MRA sequences for image quality and confidence in anastomosis interpretation, and the degree of stenosis at the arterial anastomosis. Correlations with digital subtraction angiography (DSA) were carried out when available. In addition, inter-rater agreement was calculated.

RESULTS

In total, 43 patients underwent QISS and 3D bSSFP MRA. For QISS, all cases were adequate for evaluation. For 3D SSFP, 86% of cases were adequate for evaluation. There was a good-to-excellent inter-rater agreement for all scores and an excellent correlation between NCE-MRA and DSA results when available (12 patients).

CONCLUSIONS

QISS and 3D SSFP showed good inter-rater agreement for image quality and stenosis grade, with more cases being of adequate image quality that used QISS. Further study is required; however, NCE-MRA shows potential as a risk-free alternative to CTA and contrast-enhanced MRA (CE-MRA) for the evaluation of arterial anastomoses in renal transplant patients.

Endovascular Treatment of Transplant Renal Artery Stenosis: A Systematic Review and Meta-analysis

OBJECTIVE

Endovascular treatment through either percutaneous transluminal angioplasty (PTA) alone or stenting has been previously used as a treatment for transplant renal artery stenosis (TRAS). This review aimed to investigate the results of endovascular treatment for renal artery stenosis in transplanted kidneys as compared with the outcomes of interventions, medical management, and graft survival in non-TRAS patients.

METHODS

A systematic review of PubMed, Google Scholar, Cochrane, and Scopus was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines in which studies that reported outcomes of the treatment of TRAS via the endoluminal approach were identified, and their results were meta-analyzed.

RESULTS

Fifty-four studies with a total of 1522 patients were included. A significant reduction of serum creatinine level was found, favoring the stenting group, with a mean difference of 0.68 mg/dL (95% confidence interval (CI), 0.17-1.19; Z=2.60, p=0.0009). Comparison of pre- and post-intervention values of any intervention revealed a significant decrease in overall serum creatinine level (0.65 mg/dL; 95% CI, 0.40-0.90; Z=5.09, p=0.00001), overall blood pressure, with a mean difference of 11.12 mmHg (95% CI, 7.29-14.95; Z=5.59, p=0.00001), mean difference in the use of medications (0.77; 95% CI, 0.29-1.24; p=0.002), and peak systolic velocity (190.05; 95% CI, 128.41-251.69; p<0.00001). The comparison of serum creatinine level between endovascular interventions and best medical therapy favored endovascular intervention, with a mean difference of 0.23 mg/dL (95% CI, 0.14-0.32; Z=5.07, p<0.00001). Graft survival was similar between the treated patients and those without TRAS (hazard ratio, 0.98; 95% CI, 0.75-1.28; p=0.091). The overall pooled success rate was 89%, and the overall complication rate was 10.4%, with the most prevalent complication being arterial dissection.

CONCLUSION

The endovascular treatment of TRAS improves graft preservation and renal function and hemodynamic parameters. PTA + stenting appears to be a more effective option to PTA alone in the stabilization of renal function, with additional benefits from decreased restenosis rates. Further high-quality studies could expand on these findings.

Analysis of the Peak Systolic Velocity in the Transplant Renal Artery Anastomosis to Determine Normal Values in Patients Without Graft Dysfunction

Objective:

The primary purpose is to define the mean renal artery anastomosis peak systolic velocity (RAA PSV) and the renal artery anastomosis to external iliac artery ratio (RAA-to-EIA) of renal transplant recipients without graft dysfunction. Moreover, to determine associations with type of vascular anastomosis and type of graft.

Materials and Methods:

This is a single-center retrospective analysis of kidney transplant recipients. Recorded variables included recipient age, type of vascular anastomosis, type of graft, RAA PSV, and external iliac artery PSV (EIA PSV). Such variables were evaluated on different postoperative follow-up periods.

Results:

There was a high degree of reliability between the RAA PSV and EIA PSV ( P < .001). The mean RAA PSV was 174 cm/s ± 72.9 cm/s with 95% confidence interval (CI) (162.2 cm/s-185.5 cm/s].

Conclusion:

This study highlights the importance of determining the normal range of RAA PSV and showed that a high PSV does not necessarily indicate dysfunction.

Current Status of Ultrasound in Acute Rejection After Renal Transplantation: A Review with a Focus on Contrast-Enhanced Ultrasound

Renal transplantation has developed into the best treatment for end-stage renal disease, but severe cases can even lead to loss of renal allograft function due to rejection and complications caused by surgical procedures. If a series of postoperative complications can be reduced or even avoided, the quality of life of recipients will be significantly improved. Acute rejection in a transplanted kidney is one of the main complications after renal transplantation. Early detection and diagnosis will significantly help the prognosis of transplanted kidney patients. As a seminal morphological and hemodynamic examination method, ultrasound can monitor the tissue structure and arteriovenous blood flow of the transplanted kidney, providing information on the transplanted kidney’s gross shape and blood perfusion. Ultrasound is a commonly used detection method after renal transplantation. At present, two-dimensional ultrasound, color Doppler ultrasound, three-dimensional ultrasound, and contrast-enhanced ultrasound have been applied in the monitoring of complications after renal transplantation. Contrast-enhanced ultrasound, as a non-invasive, radiation-free, and easy to perform examination technique, can qualitatively and quantitatively evaluate the microcirculatory blood perfusion of the transplanted kidney. It can reflect the function of the transplanted kidney more objectively and sensitively. In recent years, contrast-enhanced ultrasound has attracted attention as a new technology that can quantitatively monitor the transplanted kidney’s microcirculation perfusion. A large number of studies have shown that contrast-enhanced ultrasound has unique advantages in monitoring acute rejection after renal transplantation compared with other imaging methods, providing a reliable basis for clinical intervention. This article reviews the current status of and recent research on contrast-enhanced ultrasound in acute rejection after renal transplantation.

Arterial abnormalities identified in kidneys transplanted into children during the COVID-19 pandemic

Graft artery stenosis can have a significant short- and long-term negative impact on renal graft function. From the beginning of the COVID-19 pandemic, we noticed an unusual number of graft arterial anomalies following kidney transplant (KTx) in children. Nine children received a KTx at our center between February and July 2020, eight boys and one girl, of median age of 10 years. Seven presented Doppler features suggesting arterial stenosis, with an unusual extensive pattern. For comparison, over the previous 5-year period, persistent spectral Doppler arterial anomalies (focal anastomotic stenoses) following KTx were seen in 5% of children at our center. We retrospectively evidenced severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in five of seven children with arterial stenosis. The remaining two patients had received a graft from a deceased adolescent donor with a positive serology at D0. These data led us to suspect immune postviral graft vasculitis, triggered by SARS-CoV-2. Because the diagnosis of COVID-19 is challenging in children, we recommend pretransplant monitoring of graft recipients and their parents by monthly RT-PCR and serology. We suggest balancing the risk of postviral graft vasculitis against the risk of prolonged dialysis when considering transplantation in a child during the pandemic.

Multiparametric ultrasound findings in acute kidney failure due to rare renal cortical necrosis

Renal cortical necrosis (RCN) is a rare cause of acute kidney failure and is usually diagnosed on the basis of characteristic enhancement patterns on cross-sectional imaging. Contrast-enhanced ultrasound (CEUS) offers benefits in patients with kidney failure in the clinical setting including the use of a nonnephrotoxic intravascular contrast agent and the fact that it can be performed at the bedside in critical cases. Therefore, the aim of this study is to investigate whether CEUS can reliably identify typical imaging features of RCN. We retrospectively analyzed 12 patients with RCN examined in our department and confirmation of the diagnosis by either histopathology, other contrast-enhanced cross-sectional imaging tests, and/or CEUS follow-up. Assessed parameters in conventional US were reduced echogenicity, loss of corticomedullary differentiation, length and width of kidney, hypoechoic rim, resistance index and in CEUS delayed wash-in of contrast agent (> 20 s), reverse rim sign, maximum nonenhancing rim and additional renal infarction. Furthermore, imaging features in RCN were compared with the findings in renal vein thrombosis (RVT), among them echogenicity, corticomedullar differentiation, hypoechoic rim, RI value, delayed cortical enhancement, total loss of cortical perfusion and enhancement of renal medulla. All 12 patients showed the reverse rim sign, while a hypoechogenic subcapsular rim was only visible in four patients on B-mode ultrasound. A resistance index (RI) was available in 10 cases and was always less than 1. RI was a strong differentiator in separating RVT from RCN (RI > 1 or not measurable due to hypoperfusion as differentiator, p = 0.001). CEUS showed total loss of medullary enhancement in all cases of RVT. With its higher temporal resolution, CEUS allows dynamic assessment of renal macro- and microcirculation and identification of the typical imaging findings of RCN with use of a nonnephrotoxic contrast agent.

Complex Surgical Reconstruction of Upper Pole Artery in Living-Donor Kidney Transplantation

Background

The use of allografts with multiple renal arteries has increased in the era of laparoscopic donor nephrectomy. Although several studies recommend reconstructing lower pole arteries (LPAs) to reduce risk of urologic complications, it is common opinion to ligate upper pole arteries (UPAs) with a diameter less than 2 mm because of increased risk of thrombosis related to their reconstruction. This retrospective study evaluates the feasibility and safety of reconstructing thin UPAs during living-donor kidney transplantation, with the goal of maintaining the integrity of the graft and assuring its maximal function.

Material/Methods

Data from 922 living-donor kidney transplants performed between 2009 and 2019 were reviewed. Six cases with UPAs were identified (0.65%). The study endpoints were incidence of allograft vascular and urologic complications, slow graft function, delayed graft function, graft failure, and graft and patient survival.

Results

The UPAs had a mean diameter of 1.8±0.28 mm. Methods of reconstruction included: interposition graft (n=2), end-to-side anastomosis inside the renal hilum to a branch of the main renal artery (n=3), and side-to-side anastomosis with the main renal artery (n=1). Additional reconstruction of LPAs (n=2) and main renal arteries (n=2) was performed. During a median (range) follow-up of 14.5 (9–49) months no complications were observed.

Conclusions

Ex vivo reconstruction of UPAs with a diameter less than 2 mm is worth attempting, particularly in the setting of living-donor kidney transplantation.

Egyptian clinical practice guideline for kidney transplantation

Objective: To present the first Egyptian clinical practice guideline for kidney transplantation (KT).

Methods: A panel of multidisciplinary subspecialties related to KT prepared this document. The sources of information included updates of six international guidelines, and review of several relevant international and Egyptian publications. All statements were graded according to the strength of clinical practice recommendation and the level of evidence. All recommendations were discussed by the panel members who represented most of the licensed Egyptian centres practicing KT.

Results: Recommendations were given on preparation, surgical techniques and surgical complications of both donors and recipients. A special emphasis was made on the recipient’s journey with immunosuppression. It starts with setting the scene by covering the donor and recipient evaluations, medicolegal requirements, recipient’s protective vaccines, and risk assessment. It spans desensitisation and induction strategies to surgical approach and potential complications, options of maintenance immunosuppression, updated treatment of acute rejection and chemoprophylactic protocols. It ends with monitoring for potential complications of the recipient’s suppressed immunity and the short- and long-term complications of immunosuppressive drugs. It highlights the importance of individualisation of immunosuppression strategies consistent with pre-KT risk assessment. It emphasises the all-important role of anti-human leucocyte antigen antibodies, particularly the donor-specific antibodies (DSAs), in acute and chronic rejection, and eventual graft and patient survival. It addresses the place of DSAs across the recipient’s journey with his/her gift of life.

Conclusion: This guideline introduces the first proposed standard of good clinical practice in the field of KT in Egypt.

Abbreviations: Ab: antibody; ABMR: Ab-mediated rejection; ABO: ABO blood groups; BKV: BK polyomavirus; BMI: body mass index; BTS: British Transplantation Society; CAN: chronic allograft nephropathy; CDC: complement-dependent cytotoxicity; CKD: chronic kidney disease; CMV: cytomegalovirus; CNI: calcineurin inhibitor; CPRA: Calculated Panel Reactive Antibodies; (dn)DSA: (de novo) donor-specific antibodies; ECG: electrocardiogram; ESWL: extracorporeal shockwave lithotripsy; FCM: flow cytometry; GBM: glomerular basement membrane; GN: glomerulonephritis; HIV: human immunodeficiency virus; HLA: human leucocyte antigen; HPV: human papilloma virus; IL2-RA: interleukin-2 receptor antagonist; IVIg: intravenous immunoglobulin; KT(C)(R): kidney transplantation/transplant (candidate) (recipient); (L)(O)LDN: (laparoscopic) (open) live-donor nephrectomy; MBD: metabolic bone disease; MCS: Mean channel shift (in FCM-XM); MFI: mean fluorescence intensity; MMF: mycophenolate mofetil; mTOR(i): mammalian target of rapamycin (inhibitor); NG: ‘not graded’; PAP: Papanicolaou smear; PCN: percutaneous nephrostomy; PCNL: percutaneous nephrolithotomy; PKTU: post-KT urolithiasis; PLEX: plasma exchange; PRA: panel reactive antibodies; PSI: proliferation signal inhibitor; PTA: percutaneous transluminal angioplasty; RAS: renal artery stenosis; RAT: renal artery thrombosis;:rATG: rabbit anti-thymocyte globulin; RCT: randomised controlled trial; RIS: Relative MFI Score; RVT: renal vein thrombosis; TB: tuberculosis; TCMR: T-cell-mediated rejection; URS: ureterorenoscopy; (CD)US: (colour Doppler) ultrasonography; VCUG: voiding cystourethrogram; XM: cross match; ZN: Ziehl–Neelsen stain

4D flow MRI for the assessment of renal transplant dysfunction: initial results

OBJECTIVES

(1) Determine inter-observer reproducibility and test-retest repeatability of 4D flow parameters in renal allograft vessels; (2) determine if 4D flow measurements in the renal artery (RA) and renal vein (RV) can distinguish between functional and dysfunctional allografts; (3) correlate haemodynamic parameters with estimated glomerular filtration rate (eGFR), perfusion measured with dynamic contrast-enhanced MRI (DCE-MRI) and histopathology.

METHODS

Twenty-five prospectively recruited renal transplant patients (stable function/chronic renal allograft dysfunction, 12/13) underwent 4D flow MRI at 1.5 T. 4D flow coronal oblique acquisitions were performed in the transplant renal artery (RA) (velocity encoding parameter, VENC = 120 cm/s) and renal vein (RV) (VENC = 45 cm/s). Test-retest repeatability (n = 3) and inter-observer reproducibility (n = 10) were assessed by Cohen's kappa, coefficient of variation (CoV) and Bland-Altman statistics. Haemodynamic parameters were compared between patients and correlated to the estimated glomerular filtration rate, DCE-MRI parameters (n = 10) and histopathology from allograft biopsies (n = 15).

RESULTS

For inter-observer reproducibility, kappa was > 0.99 and 0.62 and CoV of flow was 12.6% and 7.8% for RA and RV, respectively. For test-retest repeatability, kappa was > 0.99 and 0.5 and CoV of flow was 27.3% and 59.4%, for RA and RV, respectively. RA (p = 0.039) and RV (p = 0.019) flow were both significantly reduced in dysfunctional allografts. Both identified chronic allograft dysfunction with good diagnostic performance (RA: AUC = 0.76, p = 0.036; RV: AUC = 0.8, p = 0.018). RA flow correlated negatively with histopathologic interstitial fibrosis score ci (ρ = - 0.6, p = 0.03).

CONCLUSIONS

4D flow parameters had better repeatability in the RA than in the RV. RA and RV flow can identify chronic renal allograft dysfunction, with RA flow correlating with histopathologic interstitial fibrosis score.

KEY POINTS

• Inter-observer reproducibility of 4D flow measurements was acceptable in both the transplant renal artery and vein, but test-retest repeatability was better in the renal artery than in the renal vein. • Blood flow measurements obtained with 4D flow MRI in the renal artery and renal vein are significantly reduced in dysfunctional renal transplants. • Renal transplant artery flow correlated negatively with histopathologic interstitial fibrosis score.

Allograft dysfunction and parenchymal necrosis associated with renal artery stenosis and perigraft hematoma after kidney transplantation

Transplant renal artery stenosis (TRAS) is one cause of allograft dysfunction. TRAS causes parenchymal necrosis and graft insufficiency. Herein, we report the case of a 40-year-old female with end-stage renal disease due to immunoglobulin A nephropathy, who underwent kidney transplantation with her elder sister. The surgery was successful and the allograft showed primary graft function. At postoperative day (POD) 2, urine output decreased sharply. We checked a non-enhanced abdominal computed tomography scan which showed subcapsular and pelvic cavity hematomas. She underwent hematoma removal surgery with renal upper polar capsulotomy. Bleeding control was successful, but her serum creatinine was 5.4 mg/dL. At POD 25, abdomen magnetic resonance angiography showed significant stenosis at the anastomosis site between the graft renal artery and the recipient’s internal iliac artery. Then, percutaneous transluminal angioplasty was implemented. Significant stenosis (>80%) was detected at the anastomotic site and a 5-mm stent was inserted at stenotic lesion with post-stent balloon angioplasty using a 5-mm balloon catheter. The renal arterial diameter and blood flow were normalized. At postoperative 5 months, a 99mTc dimercaptosuccinic acid scan showed multiple focal radioisotope defects. At 54 months after renal transplantation, her serum creatinine level was 4.0 mg/dL and her glomerular filtration rate was 13 mL/min/1.73 m². Hence, we report that TRAS can cause parenchymal necrosis and allograft dysfunction.

Usefulness of doppler techniques in the diagnosis of peripheral iatrogenic pseudoaneurysms secondary to minimally invasive interventional and surgical procedures: imaging findings and diagnostic performance study

The pseudoaneurysm (PA) is a perfused sac directly connecting with the arterial lumen by an interruption of the vessel wall continuity, more commonly secondary to trauma or iatrogenic causes. Aim of our study was to determine the accuracy and usefulness of Doppler techniques in the diagnosis of peripheral iatrogenic PAs secondary to minimally invasive procedures. From a three year prospective research, 20 Duplex Ultrasound (DUS) studies in as many patients presenting with periarterial pulsating mass clinically suspected for PA secondary to minimally invasive procedures were selected. The PA final diagnosis was confirmed by angiography in 12 patients (60% cases), by computed tomography angiography in 5 patients (25%), by surgery in 2 patients (10%), and by magnetic resonance angiography in 1 patient (5%). The vessels involved by PA formation were: common femoral artery in 8 cases (40%); superficial femoral artery in 4 cases (20%); brachial artery in 3 cases (15%); popliteal artery in 2 cases (10%); superficial temporal artery (STA) in 2 cases (10%); dorsal medial digital artery of the foot in 1 case (5%). Our study confirmed the usefulness of doppler techniques in the diagnosis of peripheral iatrogenic PAs. Specifically, a sensitivity of 90-95%, a specificity of 100% and predictive values of 100% (VPP) and 83-90% (VPN) were reported. The radiologist must always suspect a PA in the differential diagnosis of lesions contiguous to an artery vessel. This is to prevent potential complications such as e.g. massive haemorrhage. In this order, DUS allows a careful selection of patients who require to undergo in-depth imaging methods or surgical therapy, thus contributing to a significant reduction of contrast medium and exposure to ionizing radiation.

Dynamic 2-deoxy-2[18F] fluoro-D-glucose PET/MRI in human renal allotransplant patients undergoing acute kidney injury

Patients after solid organ kidney transplantation (KTX) often suffer from acute kidney injury (AKI). Parameters as serum creatinine indicate a loss of kidney function, although no distinction of the cause and prognosis can be made. Imaging tools measuring kidney function have not been widely in clinical use. In this observational study we evaluated 2-deoxy-2[18F] fluoro-D-glucose (FDG) PET/MRI in thirteen patients after KTX with AKI as a functional assessment of the graft. Twenty-four healthy volunteers served as control. General kidney performance (GKP), initial flow (IF) and renal response function (RF) were calculated by standardized uptake values (SUV) and time activity curves (TAC). The GKP measured for the total kidney and medulla was significantly higher in healthy patients compared to patients after KTX (p = 0.0002 and p = 0.0004, respectively), but no difference was found for the GKP of the cortex (p = 0.59). The IF in KTX patients correlated with renal recovery, defined as change in serum creatinine 10 days after PET/MRI (r = 0.80, p = 0.001). With regard to the RF, a negative correlation for tubular damage was found (r = -0.74, p = 0.004). In conclusion, parameters obtained from FDG PET/MRI showed a possible predictive feature for renal recovery in KTX patients undergoing AKI.

Imaging of Renal Transplant Complications throughout the Life of the Allograft: Comprehensive Multimodality Review

The kidney is the most commonly transplanted solid organ. Advances in surgical techniques, immunosuppression regimens, surveillance imaging, and histopathologic diagnosis of rejection have allowed prolonged graft survival times. However, the demand for kidneys continues to outgrow the available supply, and there are efforts to increase use of donor kidneys with moderate- or high-risk profiles. This highlights the importance of evaluating the renal transplant patient in the context of both donor and recipient risk factors. Radiologists play an integral role within the multidisciplinary team in care of the transplant patient at every stage of the transplant process. In the immediate postoperative period, duplex US is the modality of choice for evaluating the renal allograft. It is useful for establishing a baseline examination for comparison at future surveillance imaging. In the setting of allograft dysfunction, advanced imaging techniques including MRI or contrast-enhanced US may be useful for providing a more specific diagnosis and excluding nonrejection causes of renal dysfunction. When a pathologic diagnosis is deemed necessary to guide therapy, US-guided biopsy is a relatively low-risk, safe procedure. The range of complications of renal transplantation can be organized temporally in relation to the time since surgery and/or according to disease categories, including immunologic (rejection), surgical or iatrogenic, vascular, urinary, infectious, and neoplastic complications. The unique heterotopic location of the renal allograft in the iliac fossa predisposes it to a specific set of complications. As imaging features of infection or malignancy may be nonspecific, awareness of the patient's risk profile and time since transplantation can be used to assign the probability of a certain diagnosis and thus guide more specific diagnostic workup. It is critical to understand variations in vascular anatomy, surgical technique, and independent donor and recipient risk factors to make an accurate diagnosis and initiate appropriate treatment.^©RSNA, 2019.

Current status of imaging diagnosis in the transplanted kidney. A review of the literature with a special focus on contrast-enhanced ultrasonography

Objectives

Ultrasonographic scanning is currently the most widespread imaging diagnostic procedure. The method provides real-time morphological, vascular and elastographic information in a non-invasive manner. In recent years, harmonic vascular examination has become accessible using intravenous contrast agents. In urological pathology, this procedure is used in the detection and evaluation of vascular and ischemic complications, in the classification of complex cysts according to the Bosniak system, also in the renal lesions with uncertain etiology and in acute pyelonephritis for the detection of abscesses. The contrast agent (SonoVue) is angiospecific and can be used in patients transplanted immediately after surgery without adverse effects or impaired renal function. Thus, it is desirable to be used in the nephrological pathology of the renal graft and to develop diagnostic models based on the evaluation of renal microvascularization, as well as the quantitative data resulting from the graphical representation of the specific parameters. The purpose of this review is to evaluate the current state of the literature regarding the place and role of contrast substance ultrasound in the early diagnosis of acute renal graft dysfunction and to make a differential diagnosis of this pathological entity.

Method

This review quantifies the role of contrast ultrasound in the diagnosis of acute complications of the renal graft. The research was conducted based on the databases PubMed, MedScape, Cochrane, according to the search criteria such as contrast-enhanced ultrasound + kidney transplant, “time intensity curves” + “kidney transplant”, filtered for the period 2004–2018.

Results

In the nephrological pathology of the renal graft, contrast-enhanced ultrasound is a valuable tool, superior to Doppler ultrasound in predicting the evolution of the renal graft, identifying very small early defects in renal microvascularization. A number of studies succeeded in identifying acute graft dysfunction, some of which establish its etiology - humoral rejection versus acute tubular necrosis. On the other hand, the contrast-enhanced ultrasound parameters do not have the ability to distinguish between cellular and humoral rejection.

Conclusions

If, at present, the histopathological examination is the only one that can differentiate with certainty the cause of acute renal graft dysfunction, we consider that contrast-enhanced ultrasound, as a non-invasive imaging technique, opens a favorable perspective for increasing the survival of the renal graft and decreasing the complications in the renal transplant. The combination of other ultrasound techniques, together with contrast-enhanced ultrasound, could lead to the development of new diagnostic models.

Intra-arterial computed tomography angiography with ultra-low volume of iodine contrast and stent implantation in transplant renal artery stenosis in terms of contrast-induced kidney injury - a preliminary report

PURPOSE

Traditional digital subtraction angiography is still regarded as the gold standard in the diagnostics of transplant renal artery stenosis (TRAS). However, this procedure requires a high volume of iodine contrast medium for optimal visualisation of the renal artery. The aim of this study was to analyse both the usefulness and the safety of intra-arterial computed tomography angiography (IA-CTA) with ultra-low-volume iodine contrast administration in the diagnostic and therapeutic management of TRAS in patients with impaired renal transplant function.

MATERIAL AND METHODS

Thirty-three patients with a suspicion of TRAS based on Doppler-ultrasound and clinical setting underwent IA-CTA with ultra-low iodine contrast volume. A special, author-elaborated CTA protocol was used. The volume of 8-18 ml of diluted iodine contrast medium was administered through a catheter with the tip placed 2 cm below the aortic bifurcation.

RESULTS

In six patients the CTA examinations revealed TRAS in three configurations: in the anastomosis, in the trunk (critical and high-grade), or in both sections. Stenoses were treated with primary stenting obtaining favourable anatomical outcome. No intervention-related complications were observed. No contrast-induced acute kidney injury was diagnosed in this study. Mean serum creatinine concentration was 2.93 ± 0.89 mg/dl at the baseline and 2.89 ± 1.73 mg/dl and 2.17 ± 0.51 mg/dl after three and seven days from IA-CTA, respectively.

CONCLUSIONS

Intra-arterial CTA with ultra-low volume of iodine contrast seems to be a safe and reliable diagnostic tool to detect and assess TRAS in the aspect of stent implantation. Application of this imaging modality eliminates the need for a high volume of iodine contrast and thus does not adversely influence renal transplant function.

Contrast enhanced ultrasound: A review of radiology applications

Ultrasound contrast agents have been used for decades in Europe and Asia for cardiac and abdominal imaging and are now being more commonly utilized in the United States for radiology applications. Our article reviews the basics of contrast-enhanced ultrasound including how the contrast agent works, advantages and disadvantages, as well as pearls and pitfalls to help the radiologist efficiently integrate this technology into day-to-day clinical practice. We also discuss the diagnosis of focal hepatic lesions as well as off-label applications such as evaluation of renal masses.

Ultrasound imaging of the arterial system

Ultrasound (US) and Doppler are often the first imaging to be carried out for arterial disease, and with good reason. US is noninvasive, free of radiation exposure and crucial for follow up imaging. The review that follows aims to highlight the various applications of US in imaging of the arterial system.

Positional ischaemia of transplant kidney: A rare cause of early graft dysfunction

Kinking of the kidney transplant vessels late after the operation is a rare complication that can lead to significant morbidity and mortality. We present a case of positional ischemia of the renal allograft resulting from dynamic and positional kinking of the graft vasculature, which was diagnosed by ultrasonography with the patient standing. The graft was repositioned into the sub-rectus pocket and the ischaemic injury resolved.

Percutaneous transluminal angioplasty alone versus stent placement for the treatment of transplant renal artery stenosis

PURPOSE

The purposes of this retrospective study were to assess the efficacy of endovascular techniques for the treatment of transplant renal artery stenosis (TRAS) by analyzing technical and clinical success and to compare the results of percutaneous transluminal angioplasty (PTA) alone to those of stenting.

MATERIALS AND METHODS

A retrospective analysis was conducted on 31 patients who underwent endovascular treatment for TRAS between January 2012 and December 2017. There were 23 men and 8 women with a mean age of 60.5±14 (SD) years (range: 24-81 years). Ten patients (10/31; 32%; 8 men, 2 women; median age, 63 years) were treated with PTA alone and 21/31 (68%; 15 men, 6 women; median age, 65 years) with metallic stent placement. Several variables including serum creatinine level, glomerular filtration rate, arterial blood pressure value, antihypertensive medication obtained before and after treatment were compared. Technical success was assessed for each procedure. Clinical success was defined as a 15% drop in serum creatinine level, a decrease greater than 15% in mean blood pressure values or a decrease greater than 10% in mean blood pressure values with a reduction in the number of antihypertensive drugs needed for hypertension control.

RESULTS

Technical success was obtained in all patients [31/31; 100%; 95% confidence interval (CI): 89-100%] and clinical success in 27/31 patients (87%; 95%CI: 71-95%). Four patients (4/31; 13%; 95%CI: 5-29%) underwent repeat endovascular intervention. Mean serum creatinine level and mean arterial blood pressure values were significantly lower after treatment (177.4 and 93.8μmol/l, respectively) compared to before treatment (319.4 and 106.7μmol/l, respectively) in the stent group but not in the group treated with PTA alone (P=0.0012 and P=0.002, respectively).

CONCLUSION

The endovascular approach is safe and effective in the management of TRAS and stenting, depending on the morphology of the stenosis, should be the treatment of choice when possible.

Embolization of iatrogenic renal arteriovenous fistula - a case report

Renal artery pseudoaneurysms and arteriovenous fistulae most often occur as an iatrogenic complication. The article discusses a case of a patient diagnosed with an arteriovenous fistula and a pseudoaneurysm. A 64-year-old woman was admitted to the hospital due to nonspecific pain in the lumbar region. Imaging showed a typical picture of clear cell renal carcinoma. The patient was qualified for surgical treatment. After tumor resection, the patient developed microhematuria. Arteriovenous fistula and renal pseudoaneurysm were diagnosed using Doppler and computed tomography scans. The patient was qualified for arteriography with simultaneous embolization of the lesion. A follow-up evaluation confirmed the exclusion of aneurysm and fistula. Treatment outcomes were monitored using Doppler ultrasound. Doppler ultrasonography is the first method of choice in detecting and monitoring renal artery irregularities. Safety, non-invasiveness and easy access to this tool make it play a key role in the diagnosis of renal artery fistulas and pseudoaneurysms.

Endovascular Treatment of Transplant Renal Artery Stenosis: Evaluation of Postoperative Outcomes and Risk Factors for Recurrence

Angioplasty with or without stenting has become a well-established procedure to treat transplant renal artery stenosis (TRAS). We evaluated our experience on postoperative outcomes following the intervention and identified potential predictive factors of TRAS recurrence. Consecutive patients who underwent endovascular treatment of TRAS were retrospectively reviewed. The study end points were the technical success, 30-day postoperative complications, and the estimated glomerular filtration rate (eGFR). Thirty-two patients underwent endovascular treatment for TRAS. The technical success rate was 96.6%. Complications were observed for 7 (21.9%) patients: 4 had a dissection, 2 a pseudoaneurysm, and 1 (3.1%) patient developed an acute pulmonary edema. The mean eGFR significantly increased at 7 days, 3 months, and 6 months postintervention (43.1, 44.9, and 44.3 vs 33.9 mL/min/1.73 m2 preoperatively, P < .05). The TRAS recurrence was observed in 7 (21.9%) patients. These patients had significantly higher preoperative peak systolic velocity and systolic rise time (5 vs 4 m/s, P = .0383 and 103 vs 80 milliseconds, P = .0148, respectively). Endovascular treatment of TRAS is associated with high technical success and significant improvement in renal function. Further studies are required to confirm predictive factors of TRAS recurrence following endovascular treatment.

Pathological assessment of allograft nephrectomy: An Iranian experience

BACKGROUND

The aim of this study was to determine the pathologic causes of renal allograft failure in transplant nephrectomy specimens.

MATERIALS AND METHODS

In this cross-sectional study performed in the referral transplant center of Isfahan, Iran, medical files of all patients who underwent nephrectomy in 2008-2013 were studied. Age at transplantation, sex, donor's characteristics, causes of primary renal failure, duration of allograft function, and pathologic reasons of nephrectomy were extracted. Slides of nephrectomy biopsies were evaluated. Data were analyzed using SPSS.

RESULTS

Medical files of 39 individuals (male: 56.4%; mean age: 35.1 ± 16.0 years) were evaluated. The main disease of patients was hypertension (17.9%), and most cases (64.1%) were nephrectomized < 6 months posttransplantation. Renal vein thrombosis (RVT) (51.3%) and T-cell-mediated rejection (TCMR) (41.0%) were the most prevalent causes of transplanted nephrectomy. Cause of primary renal failure was correlated to nephrectomy result (P = 0.04). TCMR was the only pathologic finding in all of patients nephrectomized >2 years posttransplantation. There were 14 cases in which biopsy results showed a relationship between primary disease of patients and pathologic assessment of allograft (P = 0.04). A significant relationship between transplantation-nephrectomy interval and both the nephrectomy result and histopathologic result existed (P < 0.0001). A relationship between primary allograft biopsy appearance and further assessment of nephrectomized specimen (P < 0.001) existed as well.

CONCLUSION

The most pathologic diagnoses of nephrectomy in a period of less than and more than 6 months posttransplantation were RVT and TCMR, respectively. Early obtained allograft protocol biopsy is suggested, which leads to better diagnosis of allograft failure.

Ferumoxytol-enhanced MRI in the peripheral vasculature

Ferumoxytol is a promising non-gadolinium-based contrast agent with numerous varied magnetic resonance imaging applications. Previous reviews of vascular applications have focused primarily on cardiac and aortic applications. After considering safety concerns and technical issues, the objective of this paper is to explore peripheral applications for ferumoxytol-enhanced magnetic resonance angiography (MRA) and venography (MRV) in the upper and lower extremities. Separate searches for each of the following keywords were performed in pubmed: "ferumoxytol," "ultrasmall superparamagnetic iron oxide," and "USPIO." All studies pertaining to MRA or MRV in humans are included in this review. Case-based examples of various peripheral applications are used to supplement a relatively scant literature in this space. Ferumoxytol's unique properties including high T1 relaxivity and prolonged intravascular half-life make it the optimal vascular imaging contrast agent on the market and one whose vast potential has only begun to be tapped.

Standardized Duplex Ultrasound-Based Protocol for Early Diagnosis of Transplant Renal Artery Stenosis: Results of a Single-Institution Retrospective Cohort Study

Transplant renal artery stenosis (TRAS) is the most frequent vascular complication after kidney transplantation (KT) and has been associated with potentially reversible refractory hypertension, graft dysfunction, and reduced patient survival. The aim of the study is to describe the outcomes of a standardized Duplex Ultrasound- (DU-) based screening protocol for early diagnosis of TRAS and for selection of patients potentially requiring endovascular intervention. We retrospectively reviewed our prospectively collected database of KT from January 1998 to select patients diagnosed with TRAS. The follow-up protocol was based on a risk-adapted, dynamic subdivision of eligible KT patients in different risk categories (RC) with different protocol strategies (PS). Of 598 patients included in the study, 52 (9%) patients had hemodynamically significant TRAS and underwent percutaneous angioplasty (PTA) and stent placement. Technical and clinical success rates were 97% and 90%, respectively. 7 cases of restenosis were recorded at follow-up and treated with re-PTA plus stenting. Both DU imaging and clinical parameters improved after stent placement. Prospective high-quality studies are needed to test the efficacy and safety of our protocol in larger series. Accurate trial design and standardized reporting of patient outcomes will be key to address the current clinical needs.

[A high level of high-density lipoprotein cholesterol is a protective factor against transplant renal artery stenosis]

OBJECTIVE

To investigate the factors associated with the occurrence of transplant renal artery stenosis (TRAS).

METHODS

A retrospective analysis was conducted in 26 recipients who developed TRAS and 40 concurrent renal recipients without TRAS. We also conducted a nested case-control study in 14 patients with TRAS (TRAS-SD group) and another 14 non-TRAS recipients who received the allograft from the same donor (non-TRAS-SD group).

RESULTS

Compared with those in the concurrent recipients without TRAS, acute rejection (AR) occurred at a significantly higher incidence (P=0.004) and the warm ischemia time (WIT) was significantly longer (P=0.015) and the level of high?density lipoprotein cholesterol (HDL--C) significantly lower (P=0.009) in the recipients with TRAS. Logistic regression analysis suggested that AR (P=0.007) and prolonged WIT (P=0.046) were risk factors of TRAS while HDL-C (P=0.022) was the protective factor against TRAS. In recent years early diagnosis of TRAS had been made in increasing cases, the interval from transplantation to TRAS diagnosis became shortened steadily, and the recipients tended to have higher estimated glomerular filtration rate at the time of TRAS diagnosis.

CONCLUSION

Apart from the surgical technique, AR and prolonged WIT are also risk factors of TRAS while a high HDL-C level is the protective factor against TRAS. The improvement of the diagnostic accuracy by ultrasound is the primary factor contributing to the increased rate of early TRAS diagnosis in recent years.

Hemodynamics as Measured With Color Doppler Sonography in Early-Stage Obesity-Related Nephropathy in Children

OBJECTIVES

We retrospectively studied hemodynamic changes in the interlobar artery to assess the clinical value of color Doppler sonography for detecting preclinical obesity-related nephropathy.

METHODS

Color Doppler renal sonography was performed in 52 children with obesity-related nephropathy and 51 control children with simple obesity. The interlobar artery resistive index (RI) was measured and compared with clinical data and laboratory indicators.

RESULTS

The left RI (mean ± SD, 0.65 ± 0.05 versus 0.60 ± 0.08; t = 3.85), right RI (0.64 ± 0.03 versus 0.59 ± 0.02; t = 10.00), and mean RI (0.64 ± 0.05 versus 0.59 ± 0.06; t = 5.00) revealed large statistically significant increases in the obesity-related nephropathy group (all P < .01). In the obesity-related nephropathy group, a positive correlation was found between the mean RI and 24-hour urine trace albumin (r = 0.47; P < .01), triglycerides (r = 0.98; P < .01), and body mass index (r = 0.28; P < .05). The 24-hour urine trace albumin and triglycerides were higher in the obesity-related nephropathy group than the control group (P < .05). In the control group, a mild positive correlation was also found between the mean RI and body mass index (r = 0.24; P < .05).

CONCLUSIONS

Color Doppler sonography successfully indicated renal hemodynamic changes and has diagnostic value for early-stage obesity-related nephropathy.

Thirty Years of Experience at the First Tunisian Kidney Transplant Center

OBJECTIVES

The aim of this study was to report the results of 30 years of experience at the first kidney transplant center in Tunisia.

MATERIALS AND METHODS

All kidney transplants performed at the center between June 1986 and June 2016 were included. The study period was divided into 3 decades. Recipient and donor data and follow-up information were obtained from a local database and patient medical records. Comparative analyses were performed using the t test for continuous variables and the Χ² test for qualitative variables. Patient and graft survival rates were calculated according to the actuarial method, and comparison of survival curves was performed according to the logrank test.

RESULTS

The mean age of recipients was 32.7 ± 11.5 years (range, 6-65 y) with a gender ratio of 2.2. Duration of prekidney transplant dialysis varied from 2 months to 20 years (median, 27.5 mo); 1.7% of patients underwent transplant preemptively. Kidneys were recovered from deceased donors in 21.2% of cases and from living donors in 78.8%. The proportion of deceased donors dropped from 27.4% during the period 2006-2010 to 12.9% during the period 2011-2015 (P < .04). Patient survival rates at 1, 5, 10, 15, and 20 years were 96%, 89.3%, 79.5%, 71.1%, and 65.4%. Graft survival rates were 95%, 86.5%, 76.2%, 66.3%, and 57.2%. The annual graft loss was 2.9%, with a mortality rate of 2.4% and without significant differences between patients receiving deceased-donor and living-donor organs.

CONCLUSIONS

Kidney transplant activity remains suboptimal in our country. The reduction in deceased-donor organs could be related to the political transformations facing our country with their resulting social and economic consequences. Efforts should be made to increase governmental resources and to improve both public awareness of organ donation and the motivation of transplant teams.

Pharmacokinetic-guided dosing of factor VIII concentrate in a patient with haemophilia during renal transplantation

A 29-year-old man with severe haemophilia A and end-stage renal disease underwent a renal transplantation. To prevent bleeding, patient was treated with replacement therapy using factor VIII (FVIII) concentrate, according to National guidelines. Bayesian analysis was performed by combining observed FVIII concentrations with a population pharmacokinetic (PK) model for patients with severe haemophilia A in a perioperative setting. Application of Bayesian analysis led to accurate prediction of observed concentrations after prescribing dosing advice. We believe that PK-guided dosing of factor concentrates is a valuable step towards further individualisation of treatment in patients with bleeding disorders, especially in those patients requiring precise targeting of coagulation factor levels due to high risk of either bleeding or thrombosis, as illustrated by this patient undergoing a major surgical procedure.