Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022672 (acute tubular necrosis)
 2,175 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of cyclosporin A (CyA), an immunosuppressive agent that is potentially nephrotoxic, on the kidneys of 9 liver transplant recipients were studied with serial 99mTc-DTPA and 131I-hippuran scans. In addition, renal function was determined by measuring serum creatinine levels during the second postoperative week in the 9 unselected CyA-treated patients and, retrospectively, in a control group of 29 liver transplant recipients who had not been treated with CyA and who were selected because they had survived for at least 3 months postoperatively. The early postoperative creatinine level was significantly greater in the CyA group. Eight of the 9 CyA patients showed imaging abnormalities in all preoperative and postoperative studies. Five of the 8 patients showed a pattern similar to that of acute tubular necrosis (relatively preserved perfusion) in at least one study. Lowering the dosage of CyA permitted the continuation of therapy, and all 9 patients are alive after 8 to 14 months.
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PMID:99mTc-DTPA and 131I-hippuran findings in liver transplant recipients treated with cyclosporin A. 703 60

Nuclear medicine procedures have special indications in the follow-up of transplanted patients: In case of renal transplantation perfusion, function (glomerular filtration) and urinary flow measured by bolus application of 99mTc-DTPA is an important tool to detect and monitor acute tubular necrosis, rejection, urinary leakage, obstruction or vascular complications. This method is used for pancreatic grafts, too. To exclude rejection in case of heart transplantation more than one year after operation the antimyosin antibody scintigraphy is introduced avoiding biopsies. The radionuclide ventriculography is able to monitor heart function by determining the ejection fraction. Cholescintigraphy in liver transplants is sensitive to detect complications of bile flow. In case of an auxiliary liver transplantation a competition between two livers has been described. This method allows a distinction of functional performance of donor and recipient liver. The same problem is solved by ventilation-perfusion scan in lung transplants. Bone scintigraphy is of prognostic value for graft viability. Other radionuclide examinations have been developed to measure perfusion, glucose-, fat-metabolism to detect rejection episodes, abscesses or tumor recurrencies.
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PMID:[Functional scintigraphy in the follow-up of transplants]. 823 40

The presence of delayed graft function (DGF) following cadaver donor renal transplantation is associated with inferior graft survival as well as decreased patient survival. Delay in onset of function eliminates a valuable indicator of allograft viability, which is not easily replaced by standard diagnostic procedures. The purpose of this study was to demonstrate that a new clearance technique could be used to measure renal function minute to minute and under conditions similar to those observed in humans in the immediate posttransplantation period. A monkey model was used to provide controlled conditions. Increasing levels of ischemic injury were produced in 12 Rhesus monkeys by renal hilum cross-clamping. Real-time measurements of glomerular filtration rate (GFR) were obtained from the rate of clearance of the extracellular fluid of the GFR agent 99mTc-DTPA, as measured with a specially designed external radioactivity counting device called the ambulatory renal monitor, or ARM. GRF was measured every 2-5 min as the slope (k) of the log of activity measured minute to minute versus time. GFR measurements were correlated with blood urea nitrogen (BUN), plasma creatinine (Cr), routine light microscopy, and measurement of proliferating cell nuclear antigen (PCNA), a marker of cell proliferation. Large changes in renal function due to ischemia or ureteral obstruction were observed within minutes. In addition, the rate constant on Day 1 was predictive of peak serum Cr(R =--0.86, R2=.74, p = .0001). Acute tubular necrosis (ATN) resolution was reflected more quickly when using the rate constant (Day 1) than when using either BUN or plasma Cr (Day 3-4). Because of renal functional reserve, BUN and plasma Cr were relatively insensitive indicators of mild to moderate reductions in GFR as compared with the rate constant. We conclude that ARM is a simple method which provide an accurate, near real-time GFR readout with potential applications not only for the clinical management of patients with DGF, but also as a research tool in acute renal failure (ARF).
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PMID:Real-time monitoring of renal function during ischemic injury in the rhesus monkey. 857 Aug 62

Radiographic contrast media-induced nephrotoxicity is an important cause of acute renal failure. The indications of using contrast are usually unavoidable, compelling and continue to expand, especially in the vascular field. When acute renal failure follows such a procedure, it becomes important to establish the presence of contrast nephrotoxicity or an acute occlusive event which may have precipitated the failure. We present two cases of contrast nephrotoxicity in patients with impaired renal function. Radionuclide renal studies with 99mTc-DTPA (Patient 1) and 99mTc-MAG3 (Patient 2), confirmed the presence of acute tubular necrosis and excluded major occlusive vascular events. Renal scintigraphy remains an important but underused test which can rule out obvious renal vascular occlusion and/or support the diagnosis of contrast-related acute tubular necrosis, as the cause of renal failure in these patients.
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PMID:Contrast nephrotoxicity and the role of radionuclide renal scan. 891 85

We evaluated the usefulness of dynamic turbo FLASH MR imaging in the differential diagnosis of complications after renal transplantation in 17 patients (10 from living relatives and 7 from cadavers). Coronal turbo FLASH dynamic images were obtained every 5 sec for 5 min after an intravenous bolus injection of Gd-DTPA. Corticomedullary differentiation (CMD) on spin echo coronal T1-weighted images and MR renogram patterns of the renal cortex and medulla were obtained for quantitative analysis of the Gd-DTPA-enhanced dynamic turbo-FLASH images. The signal intensity ratio of the medulla to cortex after Gd-DTPA enhancement was compared among four groups: normal (n = 9), acute tubular necrosis (ATN) or cyclosporine A (CyA) tubulopathy (n = 6), acute rejection (AR) in the living related donor kidney (n = 4), and AR in the cadaveric kidney (n = 5). Although loss of CMD was seen in severe renal dysfunction in the transplanted kidneys, there was considerable overlap among the four groups. On dynamic study, there was significant differences in the signal intensity ratio of the medulla to cortex between normally functioning kidneys or ATN/CyA tubulopathy and AR (p < 0.01). In patients with severe renal dysfunction, the arterial cortical peak was indistinct. In conclusion, MR renograms obtained from dynamic turbo FLASH MR imaging played a significant role in evaluating dysfunction of the renal transplant.
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PMID:Functional evaluation of transplanted kidneys by Gd-DTPA enhanced turbo FLASH MR imaging. 898 4

Graft dysfunction is a common occurrence during the first weeks following renal transplantation. The current study was designed to evaluate the potential of renal magnetic resonance (MR) perfusion imaging to differentiate acute allograft rejection (AAR) from acute tubular necrosis (ATN) during the post-transplant period. Twenty-three consecutive patients with clinically suspected ATN and/or AAR and eight consecutive control patients (asymptomatic, serum creatinine concentration < 1.5 mg/dL) underwent MR perfusion imaging of the renal allograft within 64 days after transplantation. Histopathology was obtained in all cases with clinical suspicion of ATN or AAR. Sixty sequential fast gradient-recalled-echo MR images were acquired in each patient after intravenous administration of gadolinium-DTPA (0.1 mmol/kg). Histopathology revealed 6 patients with pure AAR, 4 patients with a combination of AAR and ATN, 12 patients with ATN and 1 patient with normal findings. Kidney graft recipients with normal renal function showed a moderate increase in signal intensity (SI) of the renal cortex and medulla after administration of contrast agent followed by an immediate and short decrease in SI of the medulla (biphasic medullary enhancement pattern). The increase in cortical SI of patients with AAR was significantly smaller (61 +/- 4% increase above baseline) than that measured in normal allografts (136 +/- 9% increase above baseline) (p < 0.05) and patients with ATN (129 +/- 3% increase above baseline) (p < .05). Patients with ATN had a slightly delayed and diminished cortical enhancement and an uniphasic and lesser medullary enhancement pattern compared to that observed in normal allografts (p < 0.05). A close correlation (r = 0.72) was found between serum creatinine concentration levels and changes in SI. Thus, MR imaging results and histopathology were in agreement in 22 of 23 patients (96%). MR perfusion imaging of renal allografts can be used to noninvasively differentiate ATN from AAR during the post-transplant period, and may also be helpful in cases were covert AAR is superimposing ATN during a phase of anuria. Patients with ATN can be separated from normals in the majority of cases as reflected by an uniphasic medullary enhancement pattern.
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PMID:Functional magnetic resonance imaging of human renal allografts during the post-transplant period: preliminary observations. 930 3

Nuclear imaging is used to evaluate renal allografts demonstrating delayed function after transplantation. Interpretation of the nuclear scan in the context of clinical data, provides helpful information in the management of the transplant recipient. The better quality of images obtained with technetium-99m mercaptoacetyltriglycine (Tc-99m MAG3) has made it the radiotracer of choice compared to technetium-99m diethylenetriamine pentaacetic acid (Tc-99m DTPA) for imaging of the renal allograft. Tc-99m MAG3 is cleared from the kidney by tubular secretion, whereas Tc-99m DTPA is cleared by glomerular filtration. In this report, we discuss a unique abnormality found on nuclear imaging of a renal allograft. Utilizing our understanding of the characteristic handling of various radiotracers by the kidney, we were able to demonstrate that the renal scan was consistent with an area of focal acute tubular necrosis in the newly transplanted kidney.
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PMID:Focal acute tubular necrosis in a renal allograft. 939 20

Renal transplant perfusion curves obtained using Tc-99m MAG3 differ from those with Tc-99m DTPA. The perfusion curve can be divided into a first phase (up to the first-pass peak) and a second phase (the curve after the initial peak). The second phase of the MAG3 perfusion curve is usually ascending in contrast to the descending Tc-99m DTPA curve. This ascending MAG3 curve reflects early tubular extraction of MAG3. However, the second phase of the MAG3 curve is sometimes flat or descending. We hypothesized that a flat or descending curve reflects poor early tubular extraction and therefore graft dysfunction. Ninety-two studies of 59' renal transplant patients were retrospectively reviewed. The second phase of the perfusion curve was visually classified as ascending, flat, or descending. 77.2% of studies had ascending curves, 16.3% flat curves, and 6.5% descending curves. A descending curve had a positive predictive value (PPV) of 100% for medical graft dysfunction, while a flat curve had a PPV of 93.3%. A nonascending second phase curve was specific (96.4%) but not sensitive (33.9%) for graft dysfunction. Patients with acute tubular necrosis were not significantly more likely to have a nonascending curve than those with acute rejection. There was no significant difference in creatinine level between patients with medical graft dysfunction and ascending vs. nonascending curves. A nonascending second phase Tc-99m MAG3 perfusion curve is predictive for graft dysfunction. An ascending curve is nonspecific and can be seen in both normally and poorly functioning grafts.
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PMID:Significance of early tubular extraction in the first minute of Tc-99m MAG3 renal transplant scintigraphy. 955 92

A prospective study was carried out to evaluate the role of sequential Tc 99m MAG3 renography in assessing transplant function in the early post-operative period. Twenty patients were included in the study. Studies were performed on all patients at intervals of 48-72 hours until discharge. There were 11 clinically diagnosed episodes of rejection, 9 of which were correctly diagnosed using MAG3 renography. Six episodes of rejection were diagnosed prior to the onset of clinical symptoms. Two patients with graft infarction were correctly diagnosed. Six patients had evidence of transient renographic abnormalities in the immediate post-operative phase which were not associated with clinical symptoms, all of these resolved spontaneously on subsequent examinations and were presumed to be related to resolving acute tubular necrosis (ATN). The perfusion index was of no discriminatory value in this study. Sequential Tc 99m MAG3 renography is highly sensitive but entirely nonspecific in the evaluation of pathology in the transplant kidney. Rejection in an uncomplicated transplant can be readily detected in many cases well in advance of clinical manifestations. This study demonstrates that Tc 99m MAG3 renography is certainly equal to Tc 99m DTPA renography or Iodine 131 renography in assessing early transplant function. However, Tc 9m MAG3 exposes the patient to considerably less radiation and the images are of superior quality.
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PMID:Sequential Tc 99m mercaptoacetyl-triglycine (MAG3) renography as an evaluator of early renal transplant function. 1014 44

Although visualization of the genitalia on Tc-99m DTPA transplant renography has been reported previously, its frequency and clinical significance have not been fully evaluated. The authors conducted a retrospective evaluation of 153 renal transplant scintigrams obtained in 129 patients during a 2-year period. The results showed that significant genital blood pooling occurred in nearly 50% of studies. Because the finding was commonly associated with little or no radioactive urine in the bladder, as in acute tubular necrosis or poor graft function, exaggeration of the normal blood pool was thought to be the possible cause for its occurrence. It is, however, important to distinguish genital blood-pool activity from the bladder with radioactive urine to avoid making an incorrect diagnosis.
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PMID:Genital uptake in renal transplant scintigraphy: is it normal blood pooling? 1195 68


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