Detection of Acute Tubular Necrosis Using Blood Oxygenation Level-Dependent (BOLD) MRI.

BACKGROUND/AIMS: To date, there is no imaging technique to assess tubular function in vivo. Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI) measures tissue oxygenation based on the transverse relaxation rate (R2*). The present study investigates whether BOLD MRI can assess tubular function using a tubule-specific pharmacological maneuver. METHODS: Cross sectional study with 28 participants including 9 subjects with ATN-induced acute kidney injury (AKI), 9 healthy controls, and 10 subjects with nephron sparing tumor resection (NSS) with clamping of the renal artery serving as a model of ischemia/reperfusion (I/R)-induced subclinical ATN (median clamping time 15 min, no significant decrease of eGFR, p=0.14). BOLD MRI was performed before and 5, 7, and 10 min after intravenous administration of 40 mg furosemide. RESULTS: Urinary neutrophil gelatinase-associated lipocalin was significantly higher in ATN-induced AKI and NSS subjects than in healthy controls (p=0.03 and p=0.01, respectively). Before administration of furosemide, absolute medullary R2*, cortical R2*, and medullary/cortical R2* ratio did not significantly differ between ATN-induced AKI vs. healthy controls and between NSS-I/R vs. contralateral healthy kidneys (p>0.05 each). Furosemide led to a significant decrease in the medullary and cortical R2* of healthy subjects and NSS contralateral kidneys (p<0.05 each), whereas there was no significant change of R2* in ATN-induced AKI and the NSS-I/R kidneys (p>0.05 each). CONCLUSION: BOLD-MRI is able to detect even mild tubular injury but necessitates a tubule-specific pharmacological maneuver, e.g. blocking the Na+-K+-2Cl- transporter by furosemide.

Orlistat-induced oxalate nephropathy: an under-recognised cause of chronic kidney disease.

Two patients developed kidney failure due to oxalate deposition in the kidney while taking orlistat. Cessation of orlistat was followed by partial recovery of kidney function. The mechanism by which orlistat causes hyperoxaluria and the management of orlistat-induced oxalate nephropathy is reviewed. We suggest that all patients taking orlistat are at risk of this condition, which may develop insidiously and is easily overlooked. Monitoring of kidney function of patients taking orlistat is warranted.

Clinical Scenarios in Chronic Kidney Disease: Chronic Tubulointerstitial Diseases.

Chronic tubulointerstitial diseases are a common final pathway toward chronic renal failure regardless the primary damage (glomerular, vascular or directly the tubulointerstitium). Chronic tubulointerstitial nephritis (CTN) is characterized by interstitial scarring, fibrosis and tubule atrophy, resulting in progressive chronic kidney disease. Most frequent causes of CTN are drugs, heavy metals, obstructive uropathy, nephrolithiasis, reflux disease, immunologic diseases, neoplasia, ischemia, metabolic diseases, genetics and miscellaneous. At ultrasound (US), kidneys' morphological aspect is similar in all forms of chronic interstitial nephropathy and only chronic pyelonephritis with or without reflux shows distinguishing characteristics. In interstitial nephropathy, kidneys' profiles are finely irregular and corticomedullary differentiation is altered because of a diffused hyperechogenicity. The only indirect sign of chronic interstitial damage can be derived from the value of intrarenal resistive indexes that hardly overcome 0.75. US is mandatory in clinical chronic pyelonephritis work-up because it provides information on kidney's diameter and on growth nomogram in children. Renal profiles can be more or less altered depending on the number of cortical scars and the presence of pseudonodular areas of segmental compensatory hypertrophy. In the early stages, US diagnosis of renal tuberculosis is difficult because parenchymal lesions are non-specific. US sensitivity in the diagnosis of hydronephrosis is very high, close to 100% and, finally, US is the first choice imaging technique in the diagnosis of urinary lithiasis.

Clinical Scenarios in Acute Kidney Injury: Parenchymal Acute Kidney Injury-Tubulo-Interstitial Diseases.

Acute tubular necrosis (ATN) is the most common type of acute kidney injury (AKI) related to parenchymal damage (90% of cases). It may be due to a direct kidney injury, such as sepsis, drugs, toxins, contrast media, hemoglobinuria and myoglobinuria, or it may be the consequence of a prolonged systemic ischemic injury. Conventional ultrasound (US) shows enlarged kidneys with hypoechoic pyramids. Increased volume is largely sustained by the increase of anteroposterior diameter, while longitudinal axis usually maintains its normal length. Despite the role of color Doppler in AKI still being debated, many studies demonstrate that renal resistive indexes (RIs) vary on the basis of primary disease. Moreover, several studies assessed that higher RI values are predictive of persistent AKI. Nevertheless, due to the marked heterogeneity among the studies, further investigations focused on timing of RI measurement and test performances are needed. Acute interstitial nephritis is also a frequent cause of AKI, mainly due to non-steroidal anti-inflammatory drugs and antibiotics administration. The development of acute interstitial nephritis is due to an immunological reaction against nephritogenic exogenous antigens, processed by tubular cells. In acute interstitial nephritis, as well as in ATN, conventional US does not allow a definitive diagnosis. Kidneys appear enlarged and widely hyperechoic due to interstitial edema and inflammatory infiltration. Also, in this condition, hemodynamic changes are closely correlated to the severity and the progression of the anatomical damage.

Renal Contrast-Enhanced Sonography Findings in a Model of Acute Cellular Allograft Rejection.

Noninvasive methods to diagnose and differentiate acute cellular rejection from acute tubular necrosis or acute calcineurin inhibitor toxicity are still missing. Because T lymphocytes play a decisive role in early states of rejection, we investigated the suitability and feasibility of antibody-mediated contrast-enhanced ultrasound by using microbubbles targeted to CD3(+) , CD4(+) , or CD8(+) T cells in different models of renal disease. In an established rat renal transplantation model, CD3-mediated ultrasound allows the detection of acute rejection as early as on postoperative day 2. Ultrasound signal intensities increased with the severity of inflammation. Further, an early response to therapy could be monitored by using contrast-enhanced sonography. Notably, acute tubular necrosis occurring after ischemia-reperfusion injury as well as acute calcineurin inhibitor toxicity could easily be differentiated. Finally, the quantified ultrasound signal correlated significantly with the number of infiltrating T cells obtained by histology and with CD3 mRNA levels, as well as with chemokine CXCL9, CXCL11, and CCL19 mRNA but not with KIM-1 mRNA expression, thereby representing the severity of graft inflammation but not the degree of kidney injury. In summary, we demonstrate that antibody-mediated contrast-enhanced ultrasound targeting T lymphocytes could be a promising tool for an easy and reproducible assessment of acute rejection after renal transplantation.

Resistance index measured by Doppler ultrasound as a predictor of graft function after kidney transplantation.

INTRODUCTION: Doppler ultrasound (US) has become the primary imaging technique for the evaluation of renal transplants. It provides information about the intrarenal resistance index (RI). A high RI is seen in every form of graft dysfunction. In this article, we review the utility of sonography, particularly the intrarenal RI measured early after renal transplant, as a predictor of acute and chronic clinical outcome in patients. RESULTS: RI is a valuable marker to determine graft function and related vascular complications. It reveals a strong correlation with serum creatinine levels measured days after transplant. Its elevation is typical for acute tubular necrosis and can be used to predict its duration. An RI >1 (absent end-diastolic flow) seen in the first weeks after transplant is associated with impaired renal graft recovery. In addition, it is an early predictor of chronic allograft nephropathy (even correlated with biopsy results), which will allow a change in therapy. CONCLUSIONS: RI measured serially in the early period after kidney transplantation is a valuable marker for determining renal graft function. It is also useful for demonstrating various types of graft dysfunction; however, it cannot differentiate between them. In recent studies, extrarenal factors in kidney transplantation (eg, recipient's age) may significantly influence RI in the recipient, demonstrating that RI depends on the vascular characteristics of the recipient and not on the graft itself.

Power doppler sonography in early renal transplantation: does it differentiate acute graft rejection from acute tubular necrosis?

To evaluate the role of power Doppler in the identification and differentiation between acute renal transplant rejection and acute tubular necrosis (ATN), we studied 67 live donor renal transplant recipients. All patients were examined by spectral and power Doppler sonography. Assessment of cortical perfusion (CP) by power Doppler was subjective, using our grading score system: P0 (normal CP); homogenous cortical blush extending to the capsule, P1 (reduced CP); cortical vascular cut-off at interlobular level, P2 (markedly reduced CP); scattered cortical color flow at the interlobar level. Renal biopsies were performed during acute graft dysfunction. Pathological diagnoses were based on Banff classification 1997. The Mann- Whitney test was used to test the difference between CP grades with respect to serum creatinine (SCr), and resistive index (RI). For 38 episodes of acute graft rejection grade I, power Doppler showed that CP was P1 and RI ranging from 0.78 to 0.89. For 21 episodes of acute graft rejection grade II, power Doppler showed that CP was P1, with RI ranging from 0.88 to >1. Only one case of grade III rejection had a CP of P2. Twelve biopsies of ATN had CP of P0 and RI ranging from 0.80 to 0.89 There was a statistically significant correlation between CP grading and SCr (P <0.01) as well as between CP grading and RI (P <0.05). CP grading had a higher sensitivity in the detection of early acute rejection compared with RI and cross-sectional area measurements. We conclude that power Doppler is a non-invasive sensitive technique that may help in the detection and differentiation between acute renal transplant rejection and ATN, particularly in the early post-transplantation period.

[Parenchymal complications of the transplanted kidney: the role of color-Doppler imaging]. / Le complicanze parenchimali del rene trapiantato: il ruolo dell'eco-color-Doppler.

Kidney transplantation is the treatment of choice for end-stage renal disease, given the better quality of life of transplanted patients when compared to patients on maintenance dialysis. In spite of surgical improvements and new immunosuppressive regimens, part of the transplanted grafts still develop chronic dysfunction. Ultrasonography, both in B-mode and with Doppler ultrasound, is an important diagnostic tool in case of clinical conditions which might impair kidney function. Even though ultrasonography is considered fundamental in the diagnosis of vascular and surgical complications of the transplanted kidney, its role is not fully understood in case of parenchymal complications of the graft. The specificity of Doppler ultrasound is low both in case of acute complications such as acute tubular necrosis, drug toxicity and acute rejection, and in case of chronic conditions such as chronic allograft nephropathy. Single determinations of resistance indices present low diagnostic accuracy, which is higher in case of successive measurements performed during the follow-up of the graft. Modern techniques including tissue pulsatility index, maximal fractional area and contrast-enhanced ultrasound increase the diagnostic power of ultrasonography in case of parenchymal complications of the transplanted kidney.

[Mercaptoacetyltriglycine renal scan for the differential diagnosis of acute tubular necrosis and interstitial nephritis associated to vancomycin]. / Renograma con mercaptoacetiltriglicina para el diagnóstico diferencial de necrosis tubular aguda y nefritis intersticial asociada a vancomicina.

The differential diagnosis of vancomycin associated renal toxicity includes acute tubular necrosis and interstitial nephritis. We report a case of vancomycin induced renal toxicity shown by Tc-99m mercaptoacetyltriglycine renal scan. Nephrotoxicity was evolved secondary to vancomycin used for treating a patient with meningitis. Tc-99m mercaptoacetyltriglycine renal scan may play a role in differentiation between acute tubular necrosis and tubulointerstitial nephritis of vancomycin associated renal toxicity and can facilitate the clinical decision making.

Disturbances of kidney graft perfusion as indicators of acute renal vein thrombosis in contrast-enhanced ultrasonography.

INTRODUCTION: The aim of this study was to evaluate the usefulness of contrast-enhanced ultrasound (US-CE) to diagnose acute renal vein thrombosis (ARVT), acute rejection episodes (ARE), or acute tubular necrosis (ATN) in kidney grafts. MATERIALS AND METHODS: We analyzed 171 US-CE among kidney transplantation patients in the early postoperative period. Patients underwent US-CE following a standard diagnostic protocol including real-time ultrasound (B-mode) and color Doppler ultrasound with spectral flow analysis. Tissue perfusion was analyzed based upon time-intensity curves for two regions: the renal cortex and the renal pyramids. RESULTS: Of 14 patients, in whom standard ultrasound showed high resistance parameters in the renal artery, three showed ARVT and 11 had ATN or ARE, which were confirmed by biopsy. Among patients with ARVT, the US-CE showed a lack of contrast perfusion into the cortex and renal pyramids. Patients with ARE/ATN showed slower contrast inflow into the parenchyma with reduced but still present perfusion. The differences in mean signal intensity values were significant for both the cortex and the renal pyramids: cortex: -53.8±5.4 dB versus -35.0±3.5 dB (P<.05) and pyramids: -54.8±5.4 dB versus -37.0±3.5 dB (P<.05). CONCLUSION: US-CE is a noninvasive method that provides easy, reliable differentiation of ARVT from ARE/ATN.

Perfusion of kidney graft pyramids and cortex in contrast-enhanced ultrasonography in the determination of the cause of delayed graft function.

BACKGROUND: The aim of this study was to assess the usefulness of a new ultrasound technique - contrast-enhanced ultrasound examination (US-CE) - using sulphur hexafluoride in the early post-transplant assessment of graft perfusion. Time-intensity curves (TIC) were compared with hemodynamic flow parameters (resistive index: RI) in patients with good early graft function (EGF) and acute rejection (AR) or acute tubular necrosis (ATN) as a cause of delayed graft function (DGF). MATERIAL/METHODS: US-CE was conducted in order to assess graft perfusion in the early period after kidney transplantation (72-120 hours) in 63 kidney allograft recipients: 35 with EGF and 28 with DGF. The DGF patients were later diagnosed based on graft biopsy as AR (n = 10) or ATN (n = 18). Time-intensity curves were compared with hemodynamic flow parameters typically assessed in post-operative graft diagnostics (e.g., RI). RESULTS: In the examination with US-CE in EGF patients, the regular inflow of contrast medium was demonstrated in all regions of the graft. In patients with DGF, a delay in the inflow of the contrast medium was observed, as well as significant differences in the time of inflow to the regions of interest between those 2 groups. There was a significantly longer inflow time of the contrast medium to the cortex and renal pyramids in patients with AR than in ATN recipients. CONCLUSIONS: US-CE may be a valuable diagnostic tool in the determination of the cause of DGF.

ARFI-based tissue elasticity quantification and kidney graft dysfunction: first clinical experiences.

BACKGROUND AND PURPOSE: Beyond the medical history, the clinical exam and lab findings, non-invasive ultrasound parameters such as kidney size and Doppler values (e.g. the resistive index) are important tools assisting clinical decision making in the monitoring of renal allografts. The gold standard for the diagnosis of renal allograft dysfunction remains the renal biopsy; while an invasive procedure, the justifiable necessity for this derives from its definitive nature a requirement beyond the synopses of all non-invasive tools. "Acoustic Radiation Force Impulse Imaging"(ARFI)-quantification is a novel ultrasound-based technology measuring tissue elasticity properties. So far experience related to this new method has not been reported in renal transplant follow-up. The purpose of this study was to evaluate changes in ARFI-measurements between clinically stable renal allografts and biopsy-proven transplant dysfunction. METHODS: We employed "Virtual Touch™ tissue quantification" (Siemens Acuson, S2000) for the quantitative measurement of tissue stiffness in the cortex of transplant kidneys. We performed initial baseline and later disease-evaluative ultrasound examinations in 8 renal transplant patients in a prospective study design. Patients were first examined during stable allograft function with a routine post-transplant renal ultrasound protocol. A second follow-up examination was carried out on subsequent presentation with transplant dysfunction prior to allograft biopsy and histological evaluation. All patiens were examined using ARFI-quantification (15 measurements/kidney). Resistive indices (RI) were calculated using pulsed-wave Doppler ultrasound, and transplant kidney size was measured on B-mode ultrasound images. All biopsies were evaluated histologically by a reference nephropathologist unaware of the results of the ultrasound studies. Histopathological diagnoses were based on biopsy results, taking clinical and laboratory findings into account. Finally we calculated the relative changes in ARFI-quantification, resistive indices and the absolute change of kidney size on a percentage basis at these defined assessment times and compared the results with the final pathologic diagnosis. RESULTS: Histological results enumerated five cases of acute T-cell-mediated rejection, one case of calcineurin inhibitor toxicity and two cases of acute tubular necrosis. Calcineurin inhibitor toxicity and acute tubular necrosis were subsumed as "other pathologies". Mean ARFI-values showed an average increase of more than 15% percent in transplants with histologically proven acute rejection whereas no increase was seen in transplants with other pathologies. Mean RI-values showed no increase either in the diagnostic group of acute rejection, nor in the group with other pathologies. Kidney size showed a mean absolute increase of 0.5 centimetres in allografts with acute rejection, whereas a mean decrease of 0.17 centimetres was seen in the group with other pathologies. CONCLUSION: As shown before in other studies, RI values and kidney size are of doubtful utility in the evaluation of kidney allograft dysfunction. ARFI-based elasticity measurement shows promise as a complementary non-invasive parameter in follow-on diagnosis of renal allograft rejection.

Ga-67 scintigraphy in the differential diagnosis between acute interstitial nephritis and acute tubular necrosis: an experimental study.

BACKGROUND: The differentiation between acute interstitial nephritis (AIN) and acute tubular necrosis (ATN) is crucial in patients with acute kidney injury. Gallium-67 citrate (Ga-67) has been used clinically in the differential diagnosis between these entities, but its efficacy is disputed. The aim of this study was to evaluate Ga-67 scintigraphy efficacy in the differentiation between experimental models of drug-induced AIN and ATN. METHODS: Animals were divided into three groups: AIN (n = 8), ATN (n = 8) and control (NL, n = 10). The AIN group received intraperitoneal puromycin aminonucleoside (single dose, 150 mg/kg). The ATN group received a single intraperitoneal injection of cisplatin (6 mg/kg). The NL group did not receive active drugs. All of the animals were submitted to Ga-67 scintigraphy, serum creatinine (Cr) and urinary osmolality assessment, and blinded renal histology evaluation. RESULTS: Renal Ga-67 uptake was strikingly more intense in the AIN group when compared to the ATN (P < 0.0001) and NL (P < 0.001) groups. The ATN group had increased Cr when compared to the NL group (P < 0.001) and lower urinary osmolality vs the NL (P < 0.001) and AIN (P < 0.01) groups. Renal histology showed severe acute tubular injury in the ATN group and intense interstitial inflammation in the AIN group, and was normal in control animals. CONCLUSION: Ga-67 scintigraphy was extremely effective in the differentiation between experimental drug-induced ATN and AIN.

Contrast-enhanced sonography in early kidney graft dysfunction.

OBJECTIVES: The aim of this study was a comparison of contrast-enhanced sonography (CEUS) and power Doppler ultrasound (US) findings in renal grafts within 30 days posttransplantation. METHODS: A total of 39 kidney recipients underwent CEUS (SonoVue bolus injection) and US examinations at 5 (T0), 15 (T1), and 30 (T2) days after grafting. The results were correlated with clinical findings and functional evolution. Fourteen patients displayed early acute kidney dysfunction: 10 had acute tubular necrosis (acute tubular necrosis [ATN] group); four acute rejection episodes (ARE group); 25 with normal evolution (as control, C group). Renal biopsies were performed to obtain a diagnosis in the four ATN cases and in all ARE patients. Creatinine and estimated glomerular filtration rate were used as kidney function parameters. CEUS analysis was performed both on cortical and medullary regions while US resistivity indexes (RI) were obtained on main, infrarenal, and arcuate arteries. From an analysis of CEUS time-intensity curves, we computed peak enhancement (PEAK), time to peak (TTP), mean transit time (MTT), regional blood flow (RBF) and volume (RBV), and cortical to medullary ratio of these indies (RATIO). RESULTS: An increased RI was present in the ATN and ARE groups as well as a reduced PEAK and RBF. RATIO-RBV and RATIO-MTT were lower than C among ATN cases, while TTP was higher compared to C in ARE. No statistical difference was evidence for RI between ATN and ARE groups. MTT (T0) was significantly related to creatinine at follow-up (T2). CONCLUSIONS: US and CEUS identified grafts with early dysfunction, but only some CEUS-derived parameters distinguished ATN from ARE, adding prognostic information.

Functional study of the transplanted kidney with power Doppler US and time/intensity curves.

PURPOSE: Power Doppler ultrasound (US) with time-intensity curves was used to study renal graft function both in the absence of disease and with complications (acute tubular necrosis and chronic rejection) in an attempt to identify pathognomonic patterns. Time-intensity curves allow representation of the kidneys' wash-in and wash-out phases after intravenous administration of sonographic contrast material. MATERIALS AND METHODS: Fifty-six asymptomatic renal transplant patients (36 men and 20 women), 19 of whom had altered creatinine clearance levels, were studied by power Doppler US with time-intensity curves followed by biopsy. Ten asymptomatic patients with normal creatinine clearance levels were used as controls. RESULTS: Time-intensity curve analysis enabled identification of three groups of patients: group A, consisting of 27 patients showing peak enhancement between 50 and 65 s from intravenous administration of contrast material; group B, consisting of 16 patients with peak enhancement between 135 and 235 s; group C, consisting of three patients with peak enhancement between 100 and 130 s. CONCLUSIONS: Data showed significant variations according to renal graft function (no abnormality, acute tubular necrosis or chronic rejection). Although confirmation by a larger series is required, our findings appear to indicate pathognomonic patterns in patients with chronic rejection and acute tubular necrosis.

Diagnostic value of Doppler ultrasound in differentiating prerenal azotemia from acute tubular necrosis in children.

Differentiating acute tubular necrosis (ATN) from prerenal azotemia is critical for selecting the appropriate treatment. This study was conducted to evaluate the diagnostic value of Doppler ultrasonography in differentiating ATN from prerenal azotemia in children. A total of 50 oliguric or anuric children with previous normal renal laboratory data were included. Doppler examination and calculation of resistive index (RI) was performed within 24 hours of admission and in the recovery phase of ARF. The sensitivity and specificity of RI in differentiating ATN from prerenal azotemia were assessed. At the cut-off point of RI = 0.75, the sensitivity and specificity of RI in differentiating prerenal failure and ATN was 91.3% and 85.2%, respectively. We conclude that Doppler ultrasonography is helpful in differentiating ATN from prerenal azotemia in children. The cut-off value of 0.75 has the highest accuracy for this purpose.

The role of ultrasound in renal insufficiency: the essentials.

Sonography is the best screening modality to evaluate patients presenting with renal insufficiency. Ultrasound findings can be normal in patients with renal disease, especially in prerenal azotemia and acute parenchymal renal disease. Echogenic kidneys indicate the presence of parenchymal renal disease; the kidneys may be of a normal size or enlarged. Small kidneys suggest advanced stage chronic kidney disease. Uncommonly, cystic disease of the kidney, especially adult type polycystic kidney disease may be the cause of the patient's renal insufficiency with bilaterally enlarged kidneys containing multiple cysts of various sizes. If hydronephrosis is present, the level and cause of the obstruction should be sought. When ultrasound cannot diagnose the level and cause of obstruction, other imaging modalities, including CT and MRI may be useful. When renovascular disease (arterial stenosis or venous thrombosis) is suspected, spectral and color Doppler can be useful in detecting abnormalities.

Differentiation between acute cyclosporine nephrotoxicity and acute tubular necrosis using enalaprilat renal scintigraphy in rats.

RATIONALE AND OBJECTIVES: Acute cyclosporine (CsA) nephrotoxicity cannot be easily differentiated from other renal parenchymal complications, such as acute tubular necrosis (ATN), that cause renal function impairment at the early posttransplantation period. The purpose of this study was to differentiate acute CsA nephrotoxicity from ATN using enalaprilat renal scintigraphy in rats. METHODS: Twenty-six rats were divided into 4 experimental groups: CsA group, who were treated with CsA (50 mg/kg/d) for 2 days; ATN group, who received clamping of both renal arteries for 45 minutes; vehicle group, who were treated with olive oil (1 mL/kg/d) for 2 days; and sham-operated group, who received the same surgical procedure as ATN group without clamping of renal arteries. The baseline study was performed with 300 microCi of technetium-99m diethylenetriaminepentaacetic acid and enalaprilat scintigraphy with 2 mCi of technetium-99m diethylenetriaminepentaacetic acid 5 minutes after intravenous enalaprilat injection (30 microg/kg). The changes of renogram grade and the renal function indices such as T(max), T(1/2), residual cortical activity, and mean transit time between 2 studies were analyzed. Immediately after renal scintigraphy, blood urea nitrogen and serum creatinine levels were measured and renal tissues stained by periodic acid Schiff reaction were examined in each group. RESULTS: Blood urea nitrogen and serum creatinine levels in the CsA and ATN groups were higher than their control groups (P < 0.05). Histologic study revealed severe ischemic necrosis of tubular epithelium in ATN group, but the other groups remained with essentially normal morphology. After enalaprilat injection, renal function indices became improved in CsA group, whereas they deteriorated in ATN group. The renogram grade was decreased in CsA group and increased or unchanged in ATN group after enalaprilat injection. The T(max), residual cortical activity, and mean transit time ratio were statistically different between the 2 groups on enalaprilat study (P < 0.05). CONCLUSIONS: These results suggest that enalaprilat renal scintigraphy could be used clinically in differentiating acute CsA nephrotoxicity from ATN after renal transplantation.

Diagnostic significance of semiquantitative and quantitative parameters of Tc99m-Ethylenedicystine renal allograft scintigraphy.

OBJECTIVES: No objective parameters for renal allograft evaluation have yet been described for Tc99m-Ethylenedicystine. This study evaluates the diagnostic significance of different quantitative and semi-quantitative parameters of renal allograft scintigraphy using Tc99m-Ethylenedicystine. METHODS: A total of 72 renal dynamic scintigraphic studies were performed within 2-weeks of renal transplantation in 42 patients. The graft perfusion, kidney/aorta ratio, washout index and retention index were derived from all studies. All these parameters were evaluated for their ability to distinguish between a normal graft, a graft with acute rejection (AR), and a graft with acute tubular necrosis (ATN). Histopathological verification of diagnosis was obtained in all cases. RESULTS: Studies were subdivided into 3 groups according to histopathological findings: acute rejection (n = 42), normal (n = 18) and acute tubular necrosis (n = 12). Normal allografts were visualized with in 2.66 +/- 0.59 seconds of visualization of abdominal aorta. The K/A ratio, wash out index and retention index was 15.22 +/- 6.86, 1.67 +/- 0.45, and 5.48 +/- 0.98 respectively. Allografts with ATN were visualized with in 3.36 +/- 0.80 seconds of visualization of abdominal aorta. The K/A ratio, wash out index and retention index was 12.73 +/- 6.74, 0.60 +/- 0.14, and 9.18 +/- 1.48 respectively. In AR, allografts were visualized 15.18 +/- 9.48 seconds after visualization of abdominal aorta. The K/A ratio, wash out index and retention index was 7.07 +/- 2.15, 0.63 +/- 0.11, and 2.26 +/- 1.28 respectively. CONCLUSIONS: Retention index can separate all the three condition of normal, acute rejection and acute tubular necrosis from each other. Retention index of < 4 suggests acute rejection, a value between 4 and 7 suggests normal allograft and a value of > or = 7 is suggestive of acute tubular necrosis. However, perfusion, K/A ratio and washout index can not segregate all the three groups.