Diffusion-MR in kidney transplant recipients: is diuretic stimulation a useful diagnostic tool for improving differentiation between functioning and non-functioning kidneys?

OBJECTIVES: To evaluate the effects of diuretic stimulation on Diffusion Weighted Imaging (DWI) and Diffusion Tensor Imaging (DTI) techniques in transplanted kidneys. METHODS: 33 transplanted kidney recipients underwent DWI and DTI sequences before and after furosemide. Cortical and medullary Apparent Diffusion Coefficient (ADC) and Fractional Anisotropy (FA) values were calculated in transplanted kidneys. Patients were divided into two groups according to their estimated glomerular rate filtration (Group A ≥ 60 ml/min and Group B < 60 ml/min). Wilcoxon matched pairs signed rank test was applied to compare pre- and post-furosemide values. ADC and FA values were compared between the 2 groups using a Mann-Whitney U test. Receiver Operating Curves (ROC) analysis was performed to predict normal renal function. RESULTS: Wilcoxon test revealed a statistically significant difference for all pre- and post- ADC and FA values in group B. For group A, a significant difference was found comparing pre- and post-medullary ADC and FA values (p = 0.0151 and p = 0.0054). In the comparison between group A and group B, cortical and medullary mean ADC values were significantly different before and after furosemide. With regard to medullary FA values, a significant difference was found between groups before and after diuretic stimulation (p respectively of 0.004 and 0.042). Comparing cortical FA mean values, no statistical difference was observed between groups before and after furosemide. The highest Area Under Curve values were reported for cortical ADC (0.878) and medullary ADC (0.863) before diuretic bolus. CONCLUSIONS: In transplanted kidneys, furosemide did not improve the differentiation between normal and reduced function.

Change in kidney volume after kidney transplantation in patients with autosomal polycystic kidney disease.

BACKGROUND: The indication to bilateral nephrectomy in patients with autosomal dominant polycystic kidney scheduled for kidney transplantation is controversial. Indeed, the progressive enlargement of cysts may increase the risk of complications and the need for nephrectomy. However, very few studies investigated the change in kidney volume after kidney transplantation. MATERIAL AND METHODS: In this prospective cohort study, the change in native kidney volume in polycystic patients was evaluated with magnetic resonance imaging. Forty patients were included in the study. Kidney diameters and total kidney volume were evaluated with magnetic resonance imaging in patients who underwent simultaneous nephrectomy and kidney transplantation and in patients with kidney transplant alone, before transplantation and 1 year after transplantation. RESULTS: There was a significant reduction of kidney volume after transplantation, with a mean degree of kidney diameters reduction varying from 12.24% to 14.43%. Mean total kidney volume of the 55 kidney considered in the analysis significantly reduced from 1617.94 ± 833.42 ml to 1381.42 ± 1005.73 ml (P<0.05), with a mean rate of 16.44% of volume decrease. More than 80% of patients had a volume reduction in both groups. CONCLUSIONS: Polycystic kidneys volume significantly reduces after kidney transplantation, and this would reduce the need for prophylactic bilateral nephrectomy in asymptomatic patients.

Simultaneous Native Nephrectomy and Kidney Transplantation in Patients With Autosomal Dominant Polycystic Kidney Disease.

INTRODUCTION: To evaluate the feasibility of simultaneous unilateral nephrectomy with kidney transplantation and to determine the effect of this procedure on perioperative morbidity and mortality and graft and patient survival. METHODS: Between January 2000 and May 2015, 145 patients with autosomal dominant polycystic kidney disease (ADPKD) underwent kidney transplantation. Of those, 40 (27.5%) underwent concurrent ipsilateral native nephrectomy (group NT). Patients in group NT were compared with patients with ADPKD not undergoing concurrent nephrectomy (group NT-) and asymptomatic patients undergoing pretransplant nephrectomy (group PNT). RESULTS: The average follow-up was 66 months. The graft survival rate at 1 and 5 years was 95% and 87.5% versus 93% and 76.2% in the NT and NT- groups, respectively (P = .903 and P = .544, respectively); 1-year patient survival was 100% for NT and 97% for NT- patients (P = .288), whereas 5-year patient survival was 100% and 92% for NT and NT- groups, respectively (P = .128). After propensity score matching (34 patients per group) no significant differences were observed in 1-year (97.1% in NT and 94.1%; P = 1) and 5-year (88.2% in NT and 91.2% in NT-; P = 1) graft survival, and in 1-year (100% for both groups; P = 1) and 5-year (100% in NT and 94.1% in NT-; P = 1) patient survival. Perioperative mortality was 0% among NT and 1.2% among NT- patients, whereas perioperative surgical complications were similar in both groups. One- and 5-year graft and patient survival were similar between the NT and PNT groups, but patients in the PNT group had significantly lower levels of hemoglobin and residual diuresis volumes at the time of transplant. Moreover, PNT patients had a longer pretransplant dialysis and a longer time on the waiting list. CONCLUSIONS: Simultaneous unilateral nephrectomy does not have a negative effect on patient and graft survival in patients with ADPKD and is associated with low morbidity. Pretransplant nephrectomy should be restricted only to highly symptomatic patients, whereas unilateral nephrectomy in asymptomatic patients should be performed during kidney transplantation only if massive kidney size precludes graft positioning.

First Case Report of Acute Renal Failure After Mesh-Plug Inguinal Hernia Repair in a Kidney Transplant Recipient.

Acute renal failure due to ureter compression after a mesh-plug inguinal repair in a kidney transplant recipient has not been previously reported to our knowledge. A 62-year-old man, who successfully underwent kidney transplantation from a deceased donor 6 years earlier, was admitted for elective repair of a direct inguinal hernia. The patient underwent an open mesh-plug repair of the inguinal hernia with placement of a plug in the preperitoneal space. We did not observe the transplanted ureter and bladder during dissection of the inguinal canal. Immediately after surgery, the patient became anuric, and a graft sonography demonstrated massive hydronephrosis. The serum creatinine level increased rapidly, and the patient underwent an emergency reoperation 8 hours later. During surgery, we did not identify the ureter but, immediately after plug removal, urine output increased progressively. We completed the hernia repair using the standard technique, without plug interposition, and the postoperative course was uneventful with complete resolution of graft dysfunction 3 days later. Furthermore, we reviewed the clinical features of complications related to inguinal hernia surgery. An increased risk of urological complications was reported recently in patients with a previous prosthetic hernia repair undergoing kidney transplantation, mainly due to the mesh adhesion to surrounding structures, making the extraperitoneal dissection during the transplant surgery very challenging. Moreover, older male kidney transplant recipients undergoing an inguinal hernia repair may be at higher risk of graft dysfunction due to inguinal herniation of a transplanted ureter. Mesh-plug inguinal hernia repair is a safe surgical technique, but this unique case suggests that kidney transplant recipients with inguinal hernia may be at higher risk of serious urological complications. Surgeons must be aware of the graft and ureter position before proceeding with hernia repair. A prompt diagnosis with graft sonography and abdominal computed tomography scan and emergency surgery may avoid the need for nephrostomy and may resolve graft dysfunction more rapidly.

Kidney Transplantation From Donors with Hepatitis B.

The growing demand for organ donors to supply the increasing number of patients on kidney waiting lists has led most transplant centers to develop protocols that allow safe use of organs from donors with special clinical situations previously regarded as contraindications. Deceased donors with previous hepatitis B may be a safe resource to increase the donor pool even if there is still controversy among transplantation centers regarding the use of hepatitis B surface antigen-positive donors for renal transplantation. However, when allocated to serology-matched recipients, kidney transplantation from donors with hepatitis B may result in excellent short-term outcome. Many concerns may arise in the long-term outcome, and studies must address the evaluation of the progression of liver disease and the rate of reactivation of liver disease in the recipients. Accurate selection and matching of both donor and recipient and correct post-transplant management are needed to achieve satisfactory long-term outcomes.

Diffusion weighted imaging and diffusion tensor imaging in the evaluation of transplanted kidneys.

OBJECTIVE: The aim of this study is to investigate the relation between renal indexes and functional MRI in a population of kidney transplant recipients who underwent MR with diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) of the transplanted graft. METHOD: Study population included 40 patients with single kidney transplant. The patients were divided into 3 groups, on the basis of creatinine clearance (CrCl) values calculated using Cockcroft-Gault formula: group A, including patients with normal renal function (CrCl ≥ 60 mL/min); group B, which refers to patients with moderate renal impairment (CrCl > 30 but <60 mL/min); and, finally, group C, which means severe renal deterioration (CrCl ≤ 30 mL/min). All patients were investigated with a 1.5 Tesla MRI scanner, acquiring DWI and DTI sequences. A Mann-Whitney U test was adopted to compare apparent diffusion coefficients (ADCs) and fractional anisotropy (FA) measurements between groups. Receiver operating characteristic (ROC) curves were created for prediction of normal renal function (group A) and renal failure (group C). Pearson correlation was performed between renal clearance and functional imaging parameter (ADC and FA), obtained for cortical and medullar regions. RESULTS: Mann-Whitney U test revealed a highly significant difference (p < 0.01) between patients with low CrCl (group C) and normal CrCl (group A) considering both medullar ADC and FA and cortical ADC. Regarding contiguous groups, the difference between group B and C was highly significant (p < 0.01) for medullar ADC and significant (p < 0.05) for cortical ADC and medullar FA. No difference between these groups was found considering cortical FA. Analyzing groups A and B, we found a significant difference (p < 0.05) for medullar both ADC and FA, while no difference was found for cortical ADC and FA. Strongest Pearson correlation was found between CrCl and medullar ADC (r = 0.65). For predicting normal renal function or severe renal impairment, highest values of AUC were observed using medullar ADC cut-off values (respectively 0.885 and 0.871); medullar FA showed also high accuracy (respectively 0.831 and 0.853). CONCLUSIONS: DWI and DTI are promising tools for non-invasive monitoring of renal function; medullar ADC proved to be the best parameter for renal function assessment.

Kidney transplantation from donors with hepatitis C infection.

The increasing demand for organ donors to supply the increasing number of patients on kidney waiting lists has led to most transplant centers developing protocols that allow safe utilization from donors with special clinical situations which previously were regarded as contraindications. Deceased donors with previous hepatitis C infection may represent a safe resource to expand the donor pool. When allocated to serology-matched recipients, kidney transplantation from donors with hepatitis C may result in an excellent short-term outcome and a significant reduction of time on the waiting list. Special care must be dedicated to the pre-transplant evaluation of potential candidates, particularly with regard to liver functionality and evidence of liver histological damage, such as cirrhosis, that could be a contraindication to transplantation. Pre-transplant antiviral therapy could be useful to reduce the viral load and to improve the long-term results, which may be affected by the progression of liver disease in the recipients. An accurate selection of both donor and recipient is mandatory to achieve a satisfactory long-term outcome.

Nutrition in kidney transplantation.

Organ transplantation has progressively established itself as the preferred therapy for many end-stage organ failures. However, many of these chronic diseases and their treatments can negatively affect nutritional status, leading to malnutrition and mineral deficiencies.Nutritional status is an important determinant of the clinical outcome of kidney transplant recipients.Malnutrition and obesity may represent a contraindication to transplantation in many cases and may increase the risk of postoperative complications after the transplantation. Nutritional support in kidney transplant recipients is challenging, since it must take into account the pre-transplant nutritional status, the side effects of immunosuppression, the function of the transplanted graft, the presence of infection, and the general status of the patient at the time of the transplantation.With these considerations in mind, we reviewed current literature on the impact of nutritional status on the outcome of kidney transplantation.

Conversion to sirolimus therapy in kidney transplant recipients with new onset diabetes mellitus after transplantation.

New-onset diabetes mellitus after transplantation (NODAT) may complicate 2-50% of kidney transplantation, and it is associated with reduced graft and patient survivals. In this retrospective study, we applied a conversion protocol to sirolimus in a cohort of kidney transplant recipients with NODAT. Among 344 kidney transplant recipients, 29 patients developed a NODAT (6.6%) and continued with a reduced dose of calcineurin inhibitors (CNI) (8 patients, Group A) or were converted to sirolimus (SIR) (21 patients, Group B). NODAT resolved in 37.5% and in 80% patients in Group A and Group B, respectively. In Group A, patient and graft survivals were 100% and 75%, respectively, not significantly different from Group B (83.4% and 68%, resp., P = 0.847). Graft function improved after conversion to sirolimus therapy: serum creatinine was 1.8 ± 0.7 mg/dL at the time of conversion and 1.6 ± 0.4 mg/dL five years after conversion to sirolimus therapy (P < 0.05), while in the group of patients remaining with a reduced dose of CNI, serum creatinine was 1.7 ± 0.6 mg/dL at the time of conversion and 1.65 ± 0.6 mg/dL at five-year followup (P = 0.732). This study demonstrated that the conversion from CNI to SIR in patients could improve significantly the metabolic parameters of patients with NODAT, without increasing the risk of acute graft rejection.

Primary balloon angioplasty of small (≤2 mm) cephalic veins improves primary patency of arteriovenous fistulae and decreases reintervention rates.

PURPOSE: The purpose of this study was to evaluate the effect of primary balloon angioplasty (PBA) of cephalic veins with diameter≤2 mm on patency and maturation time of autogenous radiocephalic arteriovenous fistulae (AVF) for hemodialysis. METHODS: Forty patients, all candidates for distal AVF, with a cephalic vein≤2 mm, were randomized to two different surgical procedures: (1) PBA of a long segment of the cephalic vein from the wrist up to the elbow (n=19); and (2) hydrostatic dilatation (HD) of a short venous segment (5 cm) at the level of the anastomosis (n=21). PBA was performed using a standard balloon 4×150 mm. Primary end points were primary patency and reintervention rates. Secondary end points were maturation time and the rate of working AVF. Follow-up included physical and duplex ultrasound (DUS) examinations at 1,4, and 8 weeks, and every 3 months thereafter. RESULTS: Risk factors were homogeneously distributed between the two groups. Mean vein diameter was 1.8±0.2 mm for the PBA group and 1.7±0.2 mm for HD. Immediate success rate was 100% for PBA and 67% for HD groups (P=.04). Causes of failure in the HD group included early vein thrombosis in seven patients (33%). Mean fistula maturation time was 32 days in the PBA group and 55 days in the HD group (P=.04). During the mean follow-up of 7 months, three patients underwent drug-eluting balloon angioplasty for failure of AVF to mature due to stenosis (1 in the PBA group and 2 in the HD group). Six-month reintervention rate was significantly lower in the PBA group (5%) compared with the HD group (43%) (P=.02). At 6 months, primary patency rates were 95% in the PBA group and 57% in the HD group (P=.01). Working AVF rate was 100% in the PBA vs 90% in the HD group. CONCLUSIONS: PBA of very small cephalic veins during the creation of a distal AVF for hemodialysis is a safe and feasible procedure. This technique assures excellent primary patency, maturation time, and dramatically decreases reintervention rate.