Indicators of Acute Rejection on Tc-99m DTPA Renal Scintigraphy

Deceased vs. living donor kidney transplantation in prediction of acute renal allograft rejection using Tc-99m DTPA renal scan

OBJECTIVES

No data are available regarding different prognostic values of Tc-99m diethylenetriaminepentaacetic acid (DTPA) renal scan in kidney transplantation (KT) recipients according to two distinct donor types: deceased donor KT (DDKT) and living donor KT (LDKT). We evaluated whether the interpretation of Tc-99m DTPA renal scan should be different by the donor type in predicting acute renal allograft rejection (AR).

METHODS

One hundred and seven KT recipients (61 DDKT and 46 LDKT) were included in this study. Tc-99m DTPA renal scan was performed 1 week after KT. AR was defined as pathological evidence of renal allograft rejection during the first 6 months of KT. Clinical factors and Tc-99m DTPA renal scan findings were compared between patients with and without AR. To further analyze the effect of the donor type, they were again compared within DDKT and LDKT recipients, respectively.

RESULTS

AR occurred in 15 patients (7 DDKT and 8 LDKT recipients). Among all patients, time to peak uptake (TTP) of the cortex (TTP_CX) measured by Tc-99m DTPA renal scan was independently predictive of AR. Moreover, TTP_KD (TTP of the whole transplanted kidney) and TTP_CX were the only predictors of AR among DDKT recipients. The most accurate predictors were TTP_CX and kidney area on renal scan for DDKT and LDKT, respectively. However, these parameters could not predict AR for the opposite donor type.

CONCLUSIONS

AR could be effectively predicted by Tc-99m DTPA renal scan obtained at 1 week post-KT. Different parameters should be applied according to the donor type in the prediction of AR.

Peri- and Postsurgical Evaluations of Renal Transplant

Renal transplantation is the best treatment of choice for patient with chronic renal insufficiency because it provides better quality of life and longer survival. Survival rates for grafts and patients have improved over the recent decades because of significant evolution of surgical techniques and immunosuppressive treatment. However, renal transplantation is still associated with several complications, which may result in poor outcome. Cause of allograft dysfunction, which occurs in the early or late post-transplantation period, should be recognized immediately, so that it can be managed correctly. Surgical complications are rare and include renal artery stenosis, vascular thrombosis, hematoma, ureteral obstruction, urinary leak, hematoma, lymphocele, and perinephric fluid collections. Parenchymal complications, which are histopathologically categorized according to Banff classification, include antibody-mediated rejection, T-cell mediated rejection, interstitial fibrosis and tubular atrophy, calcineurin inhibitors, acute tubular injury, and others. Detection of changes in the allograft function is an important task in the appropriate management of complications. Although first-line imaging tool in the recognition of complications is ultrasonography, radionuclide imaging is a modality capable of assessing graft function qualitatively and quantitatively. Sequential renal scintigraphy is of particular importance in the differential diagnosis of complications, which need prompt and accurate management. Renal scintigraphy within 24-48 hours of transplantation surgery is recommended to serve as a baseline for comparison when functional impairment develops. In addition, studies have shown that early renal scintigraphy has a predictive value for the short-term and long-term graft outcomes. This article focuses in the main complications after renal transplantation, their imaging findings, and the role of renal scintigraphy.

Non-invasive approaches in the diagnosis of acute rejection in kidney transplant recipients. Part I. In vivo imaging methods

Kidney transplantation (KTx) represents the best available treatment for patients with end-stage renal disease. Still, full benefits of KTx are undermined by acute rejection (AR). The diagnosis of AR ultimately relies on transplant needle biopsy. However, such an invasive procedure is associated with a significant risk of complications and is limited by sampling error and interobserver variability. In the present review, we summarize the current literature about non-invasive approaches for the diagnosis of AR in kidney transplant recipients (KTRs), including in vivo imaging, gene expression profiling and omics analyses of blood and urine samples. Most imaging techniques, like contrast-enhanced ultrasound and magnetic resonance, exploit the fact that blood flow is significantly lowered in case of AR-induced inflammation. In addition, AR-associated recruitment of activated leukocytes may be detectable by ¹⁸F-fluoro-deoxy-glucose positron emission tomography. In parallel, urine biomarkers, including CXCL9/CXCL10 or a three-gene signature of CD3ε, IP-10 and 18S RNA levels, have been identified. None of these approaches has been adopted yet in the clinical follow-up of KTRs, but standardization of procedures may help assess reproducibility and compare diagnostic yields in large prospective multicentric trials.

[Study on the findings of an immediate renal gammagraphy and its effect on the survival of a kidney graft]

INTRODUCTION

We assessed the effect of the findings of the renal gammagraphy (99mTc-DTPA) taken in the first 24 hours after the transplant in the survival of the kidney transplant.

MATERIALS AND METHOD

We retrospectively studied 413 kidney transplants carried out between January 1994 and December 2008, with emphasis on normal gammagraphic findings or alterations in the vascular, parenchymal and excretory stages, as well as their effect on the survival of the graft.

RESULTS

Of the 413 transplants, 44 (10.7%) presented alterations in the vascular stage, 256 (62%) in the parenchymal stage and 269 (65.1%) in the excretory stage. The mean follow-up of the entire group was 72.5 months (± 54.1 DE). The univariate analysis shows that the survival of the graft is significantly less in patients with alterations in the vascular stage (OR: 3; IC 95% 1.9 - 4.9 p<0.001), in the excretory stage (OR: 2.5; IC 95% 1.5 - 4; p=<0.001) in the parenchymal stage (OR: 2.21; IC 95% 1.3-3.36; p=0.001). The multivariate studies of the gammagraphic variables that affect the survival of the graft show that the presence of alterations in the vascular stage (OR: 3; IC 95% 1.9-4.9; p<0.001) in the parenchymal stage (OR: 2; IC 95% 1.2-3.3; p=0.005) are directly related to survival. This data is also confirmed by means of the actuarial survival analysis of the graft at 3 and 5 years.

CONCLUSIONS

The presence of alterations in the vascular stage and in the parenchymal stage of the renal gammagraphy immediately after the transplant are variables that affect the survival of the graft.

Kidney transplantation: structural and functional evaluation using MR Nephro-Urography

End-stage-renal disease (ESRD) is a major health issue in the United States, and the Medicare costs of ESRD totaled nearly USD 21 billion in 2005. Renal transplantation has emerged as the treatment of choice in this patient population, providing improved quality of life and lower healthcare costs compared with other treatment options. Imaging evaluation of a graft kidney plays a critical role in the postoperative care of the renal transplant patient. In the past, diagnostic evaluation of the transplant kidney has depended upon a combination of ultrasonography, computed tomography, MRI, and biopsy, used in conjunction with the patient's clinical presentation. However, new and developing advances in MR technology has lead to the development of MR Nephro-Urography (MRNU), which provides both anatomic and functional evaluation of the kidney in a single examination. It is expected that the increasing use of MRNU will have a significant impact on the management of renal transplant patients. This review describes MRNU methodology, examines known posttransplant complications, and highlights the utility of MRNU as a comprehensive imaging examination to diagnose both surgical and medical complications of the transplant kidney.

Nuclear imaging in the genitourinary tract: recent advances and future directions

For almost three decades, noninvasive radionuclide procedures for the evaluation of renal disease have been important components of nuclear medicine practice. With the introduction of new imaging agents and procedures, these techniques can provide valuable data on perfusion and function of individual kidneys. In general, these procedures are easy to perform and carry a low radiation burden and sedation is not required. Moreover, radionuclide imaging of the genitourinary tract has become an invaluable asset to clinicians in the evaluation of renal parenchyma and urologic abnormalities.