Devon John

Kidney Function: Glomerular Filtration Rate Measurement with MR Renography in Patients with Cirrhosis

PURPOSE To assess the accuracy of glomerular filtration rate (GFR) measurements obtained with low-contrast agent dose dynamic contrast material-enhanced magnetic resonance (MR) renography in patients with liver cirrhosis who underwent routine liver MR imaging, with urinary clearance of technetium 99m ((99m)Tc) pentetic acid (DTPA) as the reference standard. MATERIALS AND METHODS This HIPAA-compliant study was institutional review board approved. Written informed patient consent was obtained. Twenty patients with cirrhosis (14 men, six women; age range, 41-70 years; mean age, 54.6 years) who were scheduled for routine 1.5-T liver MR examinations to screen for hepatocellular carcinoma during a 6-month period were prospectively included. Five-minute MR renography with a 3-mL dose of gadoteridol was performed instead of a routine test-dose timing examination. The GFR was estimated at MR imaging with use of two kinetic models. In one model, only the signal intensities in the aorta and kidney parenchyma were considered, and in the other, renal cortical and medullary signal intensities were treated separately. The GFR was also calculated by using serum creatinine levels according to the Cockcroft-Gault and modification of diet in renal disease (MDRD) formulas. All patients underwent a (99m)Tc-DTPA urinary clearance examination on the same day to obtain a reference GFR measurement. The accuracies of all MR- and creatinine-based GFR estimations were compared by using Wilcoxon signed rank tests. RESULTS The mean reference GFR, based on (99m)Tc-DTPA clearance, was 74.9 mL/min/1.73 m(2) ± 27.7 (standard deviation) (range, 10.3-120.7 mL/min/1.73 m(2)). With both kinetic models, 95% of MR-based GFRs were within 30% of the reference values, whereas only 40% and 60% of Cockcroft-Gault- and MDRD-based GFRs, respectively, were within this range. MR-based GFR estimates were significantly more accurate than creatinine level-based estimates (P < .001). CONCLUSION GFR assessment with MR imaging, which outperformed the Cockcroft-Gault and MDRD formulas, adds less than 10 minutes of table time to a clinically indicated liver MR examination without ionizing radiation. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101338/-/DC1.

Quantitative Evaluation of Acute Renal Transplant Dysfunction with Low-Dose Three-dimensional MR Renography

PURPOSE To assess prospectively the ability of quantitative low-dose three-dimensional magnetic resonance (MR) renography to help identify the cause of acute graft dysfunction. MATERIALS AND METHODS This HIPAA-compliant study was approved by the institutional review board, and written informed consent was obtained. Between December 2001 and May 2009, sixty patients with transplanted kidneys (41 men and 19 women; mean age, 49 years; age range, 22-71 years) were included. Thirty-one patients had normal function and 29 had acute dysfunction due to acute rejection (n = 12), acute tubular necrosis (ATN) (n = 8), chronic rejection (n = 6), or drug toxicity (n = 3). MR renography was performed at 1.5 T with three-dimensional gradient-echo imaging. With use of a multicompartment renal model, the glomerular filtration rate (GFR) and the mean transit time (MTT) of the tracer for the vascular compartment (MTT(A)), the tubular compartment (MTT(T)), and the collecting system compartment (MTT(C)) were calculated. Also derived was MTT for the whole kidney (MTT(K) = MTT(A) + MTT(T) + MTT(C)) and fractional MTT of each compartment (MTT(A/K) = MTT(A)/MTT(K), MTT(T/K) = MTT(T)/MTT(K), MTT(C/K) = MTT(C)/MTT(K)). These parameters were compared in patients in the different study groups. Statistical analysis was performed by using analysis of covariance. RESULTS There were significant differences in GFR and MTT(K) between the acute dysfunction group (36.4 mL/min ± 20.8 [standard deviation] and 177.1 seconds ± 46.8, respectively) and the normal function group (65.9 mL/min ± 27.6 and 140.5 seconds ± 51.8, respectively) (P < .001 and P = .004). The MTT(A/K) was significantly higher in the acute rejection group (mean, 12.7% ± 2.9) than in the normal function group (mean, 8.3% ± 2.2; P < .001) or in the ATN group (mean, 7.1% ± 1.4; P < .001). The MTT(T/K) was significantly higher in the ATN group (mean, 83.2% ± 9.2) than in the normal function group (mean, 72.4% ± 10.2; P = .031) or in the acute rejection group (mean, 69.2% ± 6.1; P = .003). CONCLUSION Low-dose MR renography analyzed by using a multicompartmental tracer kinetic renal model may help to differentiate noninvasively between acute rejection and ATN after kidney transplantation.

Effect of peripheral vascular disease on kidney allograft outcomes: a study of U.S. Renal data system.

Background The U.S. Renal Data System was used to analyze renal allograft outcomes in patients with peripheral vascular disease (PVD) at the time of transplant listing. Methods We used an incident cohort of patients who underwent renal transplantation between June 2004 and September 2009. We defined PVD as symptomatic PVD at wait-listing. Comorbid conditions were diabetes mellitus, ischemic heart disease, cerebrovascular disease, hypertension, and smoking. Chi-square test, Student’s t test, and Cox regression were used for statistical associations. Results The mean graft survival was 55.3±0.40 months in patients with PVD versus 60.8±0.06 months in patients without PVD. There was an increased risk of graft failure with PVD (hazard ratio, 2.01; 95% confidence interval, 1.83–2.21; P=0.0001). After adjusting for other variables, PVD remained an independent risk factor for graft failure. Patients with PVD had lower death-censored graft survival versus patients without PVD at 1 year (93.3% vs. 96.6%), 2 years (89.7% vs. 95%), and 3 years (87.2% vs. 93.7%). All-cause mortality was higher in PVD versus without PVD (6.2% vs. 3.0%). In African Americans, the mean allograft survival was 54.8±0.98, months with PVD versus 59.7±0.135 months without PVD (P=0.0001). In non–African Americans, the mean allograft survival was 55.4±0.44 months with PVD versus 61.1±0.069 months without PVD (P=0.0001). There were no differences in survival between African Americans with PVD and non–African Americans with PVD. Conclusions Patients with PVD have inferior allograft and patient survival versus those without PVD. Caution should be exercised when placing patients with symptomatic PVD or amputation on the wait-list.

Scirrhous changes in dysplastic nodules do not indicate high‐grade status

Background and Aims: Dysplastic nodules (DN) may be divided into high‐grade and low‐grade, and the former has been known as a precancerous or borderline lesion. Recently many morphological characteristics concerning these types of DN have been reported. In the present study we attempted to evaluate the scirrhous change in DN as an indicative feature of high‐grade DN, based on the morphological and cell‐kinetic analyses using immunohistochemical stains for Ki‐67.

Selection and imaging of the living liver donor

Primum non nocere—First, do no harm: this is one of the basic tenets of medical practice. The very act of living donation violates this age-old edict. The rapidly increasing number of adult recipients and the critical shortage of cadaveric organs have forced transplant surgeons and physicians to search for suitable grafts elsewhere. The use of living liver donors for children has already had a significant impact on the pediatric waiting list. There has been considerable concern, however, regarding the rapidity with which adult-to-adult living donor transplantation has been embraced by transplant centers throughout the country compared with the very cautious and calculated start-up witnessed when living liver donation was first introduced for pediatric recipients. Children needing livers have greatly benefited from living donation and, to a lesser degree, from split-liver transplantation. The splitting of cadaveric livers has become more common, but unfortunately relatively few cadaveric organs are suitable for splitting and the procedure generally benefits an adult and a pediatric recipient and so does nothing extra to reduce the numbers of adults on the waiting list. The number of adults on the waiting list is, however, increasing at a tremendous rate, and thus the demand for solutions is great. Most living donor grafts given to adult recipients are right lobes. Left lobe grafts are not discussed in this review. The risks are considerable. Right hepatic lobectomy is a formidable procedure even in the most skilled hands. Proper donor selection is critical. The donor selection practices of four leading transplant centers are reviewed in the first segment of this review. In the second section, the imaging of potential donors is examined in more detail. Curr Opin Organ Transplant 2001, 6:350–354

Mortality after Renal Allograft Failure and Return to Dialysis

Introduction: The outcomes of patients who fail their kidney transplant and return to dialysis (RTD) has not been investigated in a nationally representative sample. We hypothesized that variations in management of transplant chronic kidney disease stage 5 leading to kidney allograft failure (KAF) and RTD, such as access, nutrition, timing of dialysis, and anemia management predict long-term survival. Methods: We used an incident cohort of patients from the United States Renal Data System who initiated hemodialysis between January 1, 2003 and December 31, 2008, after KAF. We used Cox regression analysis for statistical associations, with mortality as the primary outcome. Results: We identified 5,077 RTD patients and followed them for a mean of 30.9 ± 22.6 months. Adjusting for all possible confounders at the time of RTD, the adjusted hazards ratio (AHR) for death was increased with lack of arteriovenous fistula at initiation of dialysis (AHR 1.22, 95% CI 1.02-1.46, p = 0.03), albumin <3.5 g/dL (AHR 1.33, 95% CI 1.18-1.49, p = 0.0001), and being underweight (AHR 1.30, 95% CI 1.07-1.58, p = 0.006). Hemoglobin <10 g/dL (AHR 0.96, 95% CI 0.86-1.06, p = 0.46), type of insurance, and zip code-based median household income were not associated with higher mortality. Glomerular filtration rate <10 mL/min/1.73 m2 at time of dialysis initiation (AHR 0.83, 95% CI 0.75-0.93, p = 0.001) was associated with reduction in mortality. Conclusions: Excess mortality risk observed in patients starting dialysis after KAF is multifactorial, including nutritional issues and vascular access. Adequate preparation of patients with failing kidney transplants prior to resuming dialysis may improve outcomes.

Impact of renal posttransplantation amputation on allograft outcomes: a study of United States renal data system.

Background The prevalence of renal posttransplantation amputation and its impact on allograft and patient survival have not been widely reported. Methods We used an incident cohort of patients who underwent renal transplantation between June 2004 and September 2009. Amputation data were obtained using Medicare institutional claim forms. Baseline demographics and comorbidities, such as peripheral vascular disease (PVD), diabetes, ischemic heart disease, cerebrovascular disease, hypertension, and smoking, were captured. The chi-square and t tests were used for statistical associations. Kaplan–Meier survival curves were plotted for renal allograft and patient survival. Independent associations between patient factors and amputation were examined using multivariable Cox regression analysis. Results Of the 85,873 renal transplant recipients, 1062 patients had amputation. The prevalence of amputation was higher in those with PVD versus those without PVD at listing (5.6% vs. 1%; P=0.0001). Mean allograft survival was 55.5±0.55 months in patients with amputation versus 60.6±0.06 months in patients without amputation (P=0.0001). All-cause mortality was higher in patients with amputation versus those without amputation (19.9% vs. 7.3%; P=0.0001). Mean allograft survival was 60.97±0.67 months in non–African Americans without amputation versus 55.7±0.65 months in non–African Americans with amputation. Allograft survival was 59.73±0.13 months in African Americans without amputation versus 54.9±1.06 months in African Americans with amputation. In patients with amputation, race did not have any impact. Infectious complications were noted in 39 patients leading to death. Conclusions Amputation is associated with decreased allograft and patient survival. Early detection and preventive strategies for PVD may decrease amputation rate and improve survival.

Plasma Nitration of High-Density and Low-Density Lipoproteins in Chronic Kidney Disease Patients Receiving Kidney Transplants

Background. Functional abnormalities of high-density lipoprotein (HDL) could contribute to cardiovascular disease in chronic kidney disease patients. We measured a validated marker of HDL dysfunction, nitrated apolipoprotein A-I, in kidney transplant recipients to test the hypothesis that a functioning kidney transplant reduces serum nitrated apoA-I concentrations. Methods. Concentrations of nitrated apoA-I and apoB were measured using indirect sandwich ELISA assays on sera collected from each transplant subject before transplantation and at 1, 3, and 12 months after transplantation. Patients were excluded if they have history of diabetes, treatment with lipid-lowering medications or HIV protease inhibitors, prednisone dose > 15 mg/day, nephrotic range proteinuria, serum creatinine > 1.5 mg/dL, or active inflammatory disease. Sera from 18 transplanted patients were analyzed. Four subjects were excluded due to insufficient data. Twelve and eight patients had creatinine < 1.5 mg/dL at 3 and 12 months after transplantation, respectively. Results. Nitrated apoA-I was significantly reduced at 12 months after transplantation (p = 0.039). The decrease in apoA-I nitration was associated with significant reduction in myeloperoxidase (MPO) activity (p = 0.047). In contrast to apoA-I, nitrated apoB was not affected after kidney transplantation. Conclusions. Patients with well-functioning grafts had significant reduction in nitrated apoA-I 12 months after kidney transplantation. Further studies are needed in a large cohort to determine if nitrated apoA-I can be used as a valuable marker for cardiovascular risk stratification in chronic kidney disease.