The
n e w e ng l a n d j o u r na l
of
m e dic i n e
c or r e sp ondence
Thrombus Aspiration during Myocardial Infarction To the Editor: In the Thrombus Aspiration in ST-Segment Elevation Myocardial Infarction (STEMI) in Scandinavia (TASTE) trial, Fröbert et al. (Oct. 24 issue)1 report that routine intracoronary thrombus aspiration before primary percutaneous coronary intervention (PCI), as compared with PCI alone, did not reduce 30-day mortality in the study patients. Aspiration thrombectomy during primary PCI is recommended to reduce the coronary thrombus burden in clinical practice.2 Accordingly, we call into question the TASTE trial design. First, given the open inclusion criteria, many patients who had no or minimal evidence of thrombus on initial angiography of the target (or culprit) vessel would have been included in the study. In such circumstances, aspiration thrombectomy may have no value and may cause harm (e.g., vessel dissection). Second, balloon angioplasty may cause clot embolization and microvascular obstruction and this week’s letters 674 Thrombus Aspiration during Myocardial Infarction 676 Intrarenal Resistive Index after Renal Transplantation 678 Absence of HIV-1 after Treatment Cessation in an Infant 679 Intensity-Modulated Radiation Therapy for Prostate Cancer 680 Effects of Bracing in Adolescents with Idiopathic Scoliosis 681 The Randomized Registry Trial 682 How a Single Patient Influenced HIV Research — 15-Year Follow-up
thus limit the benefit of concomitant aspiration thrombectomy. In the TASTE trial,3 the use of balloon angioplasty before or after thrombectomy or the use of direct stenting was not described. Third, the sample size was based on the rates of cardiac death at 30 days in the Thrombus Aspiration during Percutaneous Coronary Intervention in Acute Myocardial Infarction Study (TAPAS).4 However, the primary outcome in the TASTE study was all-cause mortality at 30 days, which raises the question of whether the study was underpowered for its primary outcome. Given these reservations, we are very concerned that the negative results of this study may militate against the appropriate use of thrombectomy in high-risk patients with STEMI. Colin Berry, Ph.D., F.R.C.P. University of Glasgow Glasgow, United Kingdom [email protected]
Matthew Lee, M.R.C.P. Nadeem Ahmed, B.Med.Sci., M.B., Ch.B. Golden Jubilee National Hospital Clydebank, United Kingdom No potential conflict of interest relevant to this letter was reported. 1. Fröbert O, Lagerqvist B, Olivecrona GK, et al. Thrombus aspi-
ration during ST-segment elevation myocardial infarction. N Engl J Med 2013;369:1587-97. 2. Task Force on the Management of ST-Segment Elevation Acute Myocardial Infarction of the European Society of Cardiology (ESC), Steg PG, James SK, et al. ESC guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation. Eur Heart J 2012;33:2569-619. 3. Fröbert O, Lagerqvist B, Gudnason T, et al. Thrombus Aspiration in ST-Elevation myocardial infarction in Scandinavia (TASTE trial). A multicenter, prospective, randomized, controlled clinical registry trial based on the Swedish Angiography and Angioplasty Registry (SCAAR) platform: study design and rationale. Am Heart J 2010;160:1042-8. 4. Svilaas T, Vlaar PJ, van der Horst IC, et al. Thrombus aspiration during primary percutaneous coronary intervention. N Engl J Med 2008;358:557-67. DOI: 10.1056/NEJMc1315678
674
n engl j med 370;7 nejm.org february 13, 2014
The New England Journal of Medicine Downloaded from nejm.org at RUTGERS UNIV ALEXANDER LIBRARY on August 11, 2015. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
correspondence
To the Editor: The negative results of the TASTE study are not unexpected, since all previous studies regarding manual thrombus aspiration did not show any effect on infarct size, which is the link to a better outcome in this population of patients. Although results of trials of rheolytic thrombectomy are conflicting, two studies showed an effect on infarct size1 and on clinical benefit.2 More important, the only direct comparison study of rheolytic thrombectomy with manual thrombus aspiration as measured by optical coherence tomography showed that rheolytic thrombectomy was more effective than manual thrombus aspiration in reducing the thrombus burden.3 We do not know whether a more effective thrombectomy device such as rheolytic thrombectomy might have provided better outcomes than manual thrombus aspiration. Guido Parodi, M.D., Ph.D. Angela Migliorini, M.D.
In the TASTE trial, only 2216 patients (30.6%) had a large thrombus burden, whereas the vast majority, 4950 patients (68.3%), had an overall small thrombus burden. Therefore, although the subgroup analysis of thrombus grade did not show significant differences, given the low rate of events and the limited number of patients in each group, further investigations are needed to fully evaluate the effect of thrombus aspiration in patients with a large thrombus burden. Roberto Diletti, M.D. Patrick W. Serruys, M.D., Ph.D. Erasmus Medical Center Rotterdam, the Netherlands [email protected] No potential conflict of interest relevant to this letter was reported. 1. Sianos G, Papafaklis MI, Daemen J, et al. Angiographic stent
thrombosis after routine use of drug-eluting stents in ST-segment elevation myocardial infarction: the importance of thrombus burden. J Am Coll Cardiol 2007;50:573-83.
Careggi Hospital Florence, Italy [email protected]
DOI: 10.1056/NEJMc1315678
Alfredo E. Rodriguez, M.D.
The authors reply: In response to Berry et al.: we designed our study to test the hypothesis that routine use of thrombus aspiration as an adjunct to primary PCI reduces mortality. With an allcomers study that was larger than all previously published randomized trials on thrombus aspiration for STEMI combined, we were unable to show a reduction in the primary end point in patients undergoing thrombus aspiration. Although a type II statistical error cannot be ruled out, the number that would need to be treated in an even larger study with a hazard ratio of 0.94 would make the potential absolute benefit clinically questionable. By intent, the design was nearly identical to that of TAPAS1 and recommended balloon angioplasty with the use of a maximum 2-mm balloon before aspiration only if the aspiration catheter could not be advanced without ballooning. The TAPAS investigators found that thrombus was frequently aspirated despite a lack of angiographic evidence of its presence. Neither TAPAS nor our study showed that patients had ill effects associated with thrombus aspiration. Our sample size was based on all-cause mortality in our national registry records and the hazard ratio in TAPAS. Berry et al. argue for an “appropriate use” of thrombus aspiration without defining what that might be. The results of our study were consistent across all
Otamendi Hospital Buenos Aires, Argentina No potential conflict of interest relevant to this letter was reported. 1. Antoniucci D, Valenti R, Migliorini A, et al. A randomized
trial comparing rheolytic thrombectomy before infarct artery stenting with stenting alone in patients undergoing percutaneous coronary intervention for acute myocardial infarction. Am J Cardiol 2004;93:1033-5. 2. Migliorini A, Stabile A, Rodriguez AE, et al. Comparison of AngioJet rheolytic thrombectomy before direct infarct artery stenting with direct stenting alone in patients with acute myocardial infarction: the JETSTENT trial. J Am Coll Cardiol 2010; 56:1298-306. 3. Parodi G, Valenti R, Migliorini A, et al. Comparison of manual thrombus aspiration with rheolytic thrombectomy in acute myocardial infarction. Circ Cardiovasc Interv 2013;6:224-30. DOI: 10.1056/NEJMc1315678
To the Editor: In the TASTE study, 2575 of 7244 patients (35.5%) had a thrombus burden of grade G0 or G1. Therefore, in more than one third of the patients, there was no clear angiographic evidence of thrombus in the culprit lesion. It is reasonable to hypothesize that in this large subgroup, the effect of thrombus aspiration on clinical outcomes is limited. Our group previously found that a large thrombus burden (grade G4 to G5) is an independent predictor of 30-day mortality, whereas a small thrombus burden (grade G0 to G3) has a limited effect on mortality.1
n engl j med 370;7 nejm.org february 13, 2014
675
The New England Journal of Medicine Downloaded from nejm.org at RUTGERS UNIV ALEXANDER LIBRARY on August 11, 2015. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
The
n e w e ng l a n d j o u r na l
subgroups and identified no benefit in several categories of high-risk patients. Therefore, the most appropriate scientific interpretation of the results is that routine thrombus aspiration does not reduce 30-day mortality in any subgroup. Parodi et al. state that the neutral outcome in our study was not unexpected. However, a possible survival benefit was the focus of a number of meta-analyses2-4 that preceded the initiation of our study and justifies our hypothesis. In our study, we evaluated manual aspiration only. An adequately powered study of rheolytic thrombectomy is needed before it can be recommended. Diletti and Serruys express concern that a third of the patients in our study had a thrombus burden of grade G0 or G1. However, the primary end point, 30-day mortality, was consistent across all major subgroups, with no significant P values for interaction. This included patients with highgrade thrombus (2216 patients presented with a large thrombus burden, twice the total number of patients included in TAPAS) and those with variables that suggest an increased thrombotic risk, such as smoking, a low Thrombolysis in Myocardial Infarction flow grade, and a short
of
m e dic i n e
time from the onset of symptoms (as shown in Fig. 3 of our article). Ole Fröbert, M.D., Ph.D. Örebro University Hospital Örebro, Sweden [email protected]
Stefan K. James, M.D., Ph.D. Uppsala University Uppsala, Sweden
for the TASTE Research Group Since publication of their article, the authors report no further potential conflict of interest. 1. Svilaas T, Vlaar PJ, van der Horst IC, et al. Thrombus aspira-
tion during primary percutaneous coronary intervention. N Engl J Med 2008;358:557-67. 2. Kumbhani DJ, Bavry AA, Desai MY, Bangalore S, Bhatt DL. Role of aspiration and mechanical thrombectomy in patients with acute myocardial infarction undergoing primary angioplasty: an updated meta-analysis of randomized trials. J Am Coll Cardiol 2013;62:1409-18. 3. Mongeon FP, Bélisle P, Joseph L, Eisenberg MJ, Rinfret S. Adjunctive thrombectomy for acute myocardial infarction: a Bayesian meta-analysis. Circ Cardiovasc Interv 2010;3:6-16. 4. De Luca G, Dudek D, Sardella G, Marino P, Chevalier B, Zijlstra F. Adjunctive manual thrombectomy improves myocardial perfusion and mortality in patients undergoing primary percutaneous coronary intervention for ST-elevation myocardial infarction: a meta-analysis of randomized trials. Eur Heart J 2008;29: 3002-10. DOI: 10.1056/NEJMc1315678
Intrarenal Resistive Index after Renal Transplantation To the Editor: Naesens et al. (Nov. 7 issue)1 published their findings of a well-conducted study looking at the relationship between intrarenal resistive indexes in renal allografts and allograft dysfunction. With regard to the protocolspecified measurements, higher resistive indexes were not associated with allograft dysfunction but were associated with older recipient age and increased mortality. After reading the article, my colleagues and I had a few questions and comments. First, what is the rationale for using a cutoff value of 0.80 to distinguish a lower resistive index from a higher resistive index and for treating the resistive index as a categorical variable when it is in fact a continuous variable? Second, the intraobserver variability and interobserver variability in the study were very low at less than 5% each, but we wonder if this will hold true for the external validity of the results. Third, noninvasive assessment of renal-allograft function is an actively pursued area of investigation in many centers, including ours. In that regard, various 676
types of magnetic resonance imaging (MRI), including blood oxygen level–dependent MRI,2 arterial spin labeling MRI,3 and diffusion-weighted MRI,4 also seem to have shown promising results. Nagaraju Sarabu, M.D., M.P.H. University Hospitals Case Medical Center Cleveland, OH [email protected] No potential conflict of interest relevant to this letter was reported. 1. Naesens M, Heylen L, Lerut E, et al. Intrarenal resistive index
after renal transplantation. N Engl J Med 2013;369:1797-806.
2. Djamali A, Sadowski EA, Muehrer RJ, et al. BOLD-MRI as-
sessment of intrarenal oxygenation and oxidative stress in patients with chronic kidney allograft dysfunction. Am J Physiol Renal Physiol 2007;292:F513-F522. 3. Heusch P, Wittsack HJ, Blondin D, et al. Functional evaluation of transplanted kidneys using arterial spin labeling MRI. J Magn Reson Imaging 2013 October 7 (Epub ahead of print). 4. Abou-El-Ghar ME, El-Diasty TA, El-Assmy AM, Refaie HF, Refaie AF, Ghoneim MA. Role of diffusion-weighted MRI in diagnosis of acute renal allograft dysfunction: a prospective preliminary study. Br J Radiol 2012;85:e206-e211. DOI: 10.1056/NEJMc1315502
n engl j med 370;7 nejm.org february 13, 2014
The New England Journal of Medicine Downloaded from nejm.org at RUTGERS UNIV ALEXANDER LIBRARY on August 11, 2015. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
n e w e ng l a n d j o u r na l
of
m e dic i n e
c or r e sp ondence
Thrombus Aspiration during Myocardial Infarction To the Editor: In the Thrombus Aspiration in ST-Segment Elevation Myocardial Infarction (STEMI) in Scandinavia (TASTE) trial, Fröbert et al. (Oct. 24 issue)1 report that routine intracoronary thrombus aspiration before primary percutaneous coronary intervention (PCI), as compared with PCI alone, did not reduce 30-day mortality in the study patients. Aspiration thrombectomy during primary PCI is recommended to reduce the coronary thrombus burden in clinical practice.2 Accordingly, we call into question the TASTE trial design. First, given the open inclusion criteria, many patients who had no or minimal evidence of thrombus on initial angiography of the target (or culprit) vessel would have been included in the study. In such circumstances, aspiration thrombectomy may have no value and may cause harm (e.g., vessel dissection). Second, balloon angioplasty may cause clot embolization and microvascular obstruction and this week’s letters 674 Thrombus Aspiration during Myocardial Infarction 676 Intrarenal Resistive Index after Renal Transplantation 678 Absence of HIV-1 after Treatment Cessation in an Infant 679 Intensity-Modulated Radiation Therapy for Prostate Cancer 680 Effects of Bracing in Adolescents with Idiopathic Scoliosis 681 The Randomized Registry Trial 682 How a Single Patient Influenced HIV Research — 15-Year Follow-up
thus limit the benefit of concomitant aspiration thrombectomy. In the TASTE trial,3 the use of balloon angioplasty before or after thrombectomy or the use of direct stenting was not described. Third, the sample size was based on the rates of cardiac death at 30 days in the Thrombus Aspiration during Percutaneous Coronary Intervention in Acute Myocardial Infarction Study (TAPAS).4 However, the primary outcome in the TASTE study was all-cause mortality at 30 days, which raises the question of whether the study was underpowered for its primary outcome. Given these reservations, we are very concerned that the negative results of this study may militate against the appropriate use of thrombectomy in high-risk patients with STEMI. Colin Berry, Ph.D., F.R.C.P. University of Glasgow Glasgow, United Kingdom [email protected]
Matthew Lee, M.R.C.P. Nadeem Ahmed, B.Med.Sci., M.B., Ch.B. Golden Jubilee National Hospital Clydebank, United Kingdom No potential conflict of interest relevant to this letter was reported. 1. Fröbert O, Lagerqvist B, Olivecrona GK, et al. Thrombus aspi-
ration during ST-segment elevation myocardial infarction. N Engl J Med 2013;369:1587-97. 2. Task Force on the Management of ST-Segment Elevation Acute Myocardial Infarction of the European Society of Cardiology (ESC), Steg PG, James SK, et al. ESC guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation. Eur Heart J 2012;33:2569-619. 3. Fröbert O, Lagerqvist B, Gudnason T, et al. Thrombus Aspiration in ST-Elevation myocardial infarction in Scandinavia (TASTE trial). A multicenter, prospective, randomized, controlled clinical registry trial based on the Swedish Angiography and Angioplasty Registry (SCAAR) platform: study design and rationale. Am Heart J 2010;160:1042-8. 4. Svilaas T, Vlaar PJ, van der Horst IC, et al. Thrombus aspiration during primary percutaneous coronary intervention. N Engl J Med 2008;358:557-67. DOI: 10.1056/NEJMc1315678
674
n engl j med 370;7 nejm.org february 13, 2014
The New England Journal of Medicine Downloaded from nejm.org at RUTGERS UNIV ALEXANDER LIBRARY on August 11, 2015. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
correspondence
To the Editor: The negative results of the TASTE study are not unexpected, since all previous studies regarding manual thrombus aspiration did not show any effect on infarct size, which is the link to a better outcome in this population of patients. Although results of trials of rheolytic thrombectomy are conflicting, two studies showed an effect on infarct size1 and on clinical benefit.2 More important, the only direct comparison study of rheolytic thrombectomy with manual thrombus aspiration as measured by optical coherence tomography showed that rheolytic thrombectomy was more effective than manual thrombus aspiration in reducing the thrombus burden.3 We do not know whether a more effective thrombectomy device such as rheolytic thrombectomy might have provided better outcomes than manual thrombus aspiration. Guido Parodi, M.D., Ph.D. Angela Migliorini, M.D.
In the TASTE trial, only 2216 patients (30.6%) had a large thrombus burden, whereas the vast majority, 4950 patients (68.3%), had an overall small thrombus burden. Therefore, although the subgroup analysis of thrombus grade did not show significant differences, given the low rate of events and the limited number of patients in each group, further investigations are needed to fully evaluate the effect of thrombus aspiration in patients with a large thrombus burden. Roberto Diletti, M.D. Patrick W. Serruys, M.D., Ph.D. Erasmus Medical Center Rotterdam, the Netherlands [email protected] No potential conflict of interest relevant to this letter was reported. 1. Sianos G, Papafaklis MI, Daemen J, et al. Angiographic stent
thrombosis after routine use of drug-eluting stents in ST-segment elevation myocardial infarction: the importance of thrombus burden. J Am Coll Cardiol 2007;50:573-83.
Careggi Hospital Florence, Italy [email protected]
DOI: 10.1056/NEJMc1315678
Alfredo E. Rodriguez, M.D.
The authors reply: In response to Berry et al.: we designed our study to test the hypothesis that routine use of thrombus aspiration as an adjunct to primary PCI reduces mortality. With an allcomers study that was larger than all previously published randomized trials on thrombus aspiration for STEMI combined, we were unable to show a reduction in the primary end point in patients undergoing thrombus aspiration. Although a type II statistical error cannot be ruled out, the number that would need to be treated in an even larger study with a hazard ratio of 0.94 would make the potential absolute benefit clinically questionable. By intent, the design was nearly identical to that of TAPAS1 and recommended balloon angioplasty with the use of a maximum 2-mm balloon before aspiration only if the aspiration catheter could not be advanced without ballooning. The TAPAS investigators found that thrombus was frequently aspirated despite a lack of angiographic evidence of its presence. Neither TAPAS nor our study showed that patients had ill effects associated with thrombus aspiration. Our sample size was based on all-cause mortality in our national registry records and the hazard ratio in TAPAS. Berry et al. argue for an “appropriate use” of thrombus aspiration without defining what that might be. The results of our study were consistent across all
Otamendi Hospital Buenos Aires, Argentina No potential conflict of interest relevant to this letter was reported. 1. Antoniucci D, Valenti R, Migliorini A, et al. A randomized
trial comparing rheolytic thrombectomy before infarct artery stenting with stenting alone in patients undergoing percutaneous coronary intervention for acute myocardial infarction. Am J Cardiol 2004;93:1033-5. 2. Migliorini A, Stabile A, Rodriguez AE, et al. Comparison of AngioJet rheolytic thrombectomy before direct infarct artery stenting with direct stenting alone in patients with acute myocardial infarction: the JETSTENT trial. J Am Coll Cardiol 2010; 56:1298-306. 3. Parodi G, Valenti R, Migliorini A, et al. Comparison of manual thrombus aspiration with rheolytic thrombectomy in acute myocardial infarction. Circ Cardiovasc Interv 2013;6:224-30. DOI: 10.1056/NEJMc1315678
To the Editor: In the TASTE study, 2575 of 7244 patients (35.5%) had a thrombus burden of grade G0 or G1. Therefore, in more than one third of the patients, there was no clear angiographic evidence of thrombus in the culprit lesion. It is reasonable to hypothesize that in this large subgroup, the effect of thrombus aspiration on clinical outcomes is limited. Our group previously found that a large thrombus burden (grade G4 to G5) is an independent predictor of 30-day mortality, whereas a small thrombus burden (grade G0 to G3) has a limited effect on mortality.1
n engl j med 370;7 nejm.org february 13, 2014
675
The New England Journal of Medicine Downloaded from nejm.org at RUTGERS UNIV ALEXANDER LIBRARY on August 11, 2015. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
The
n e w e ng l a n d j o u r na l
subgroups and identified no benefit in several categories of high-risk patients. Therefore, the most appropriate scientific interpretation of the results is that routine thrombus aspiration does not reduce 30-day mortality in any subgroup. Parodi et al. state that the neutral outcome in our study was not unexpected. However, a possible survival benefit was the focus of a number of meta-analyses2-4 that preceded the initiation of our study and justifies our hypothesis. In our study, we evaluated manual aspiration only. An adequately powered study of rheolytic thrombectomy is needed before it can be recommended. Diletti and Serruys express concern that a third of the patients in our study had a thrombus burden of grade G0 or G1. However, the primary end point, 30-day mortality, was consistent across all major subgroups, with no significant P values for interaction. This included patients with highgrade thrombus (2216 patients presented with a large thrombus burden, twice the total number of patients included in TAPAS) and those with variables that suggest an increased thrombotic risk, such as smoking, a low Thrombolysis in Myocardial Infarction flow grade, and a short
of
m e dic i n e
time from the onset of symptoms (as shown in Fig. 3 of our article). Ole Fröbert, M.D., Ph.D. Örebro University Hospital Örebro, Sweden [email protected]
Stefan K. James, M.D., Ph.D. Uppsala University Uppsala, Sweden
for the TASTE Research Group Since publication of their article, the authors report no further potential conflict of interest. 1. Svilaas T, Vlaar PJ, van der Horst IC, et al. Thrombus aspira-
tion during primary percutaneous coronary intervention. N Engl J Med 2008;358:557-67. 2. Kumbhani DJ, Bavry AA, Desai MY, Bangalore S, Bhatt DL. Role of aspiration and mechanical thrombectomy in patients with acute myocardial infarction undergoing primary angioplasty: an updated meta-analysis of randomized trials. J Am Coll Cardiol 2013;62:1409-18. 3. Mongeon FP, Bélisle P, Joseph L, Eisenberg MJ, Rinfret S. Adjunctive thrombectomy for acute myocardial infarction: a Bayesian meta-analysis. Circ Cardiovasc Interv 2010;3:6-16. 4. De Luca G, Dudek D, Sardella G, Marino P, Chevalier B, Zijlstra F. Adjunctive manual thrombectomy improves myocardial perfusion and mortality in patients undergoing primary percutaneous coronary intervention for ST-elevation myocardial infarction: a meta-analysis of randomized trials. Eur Heart J 2008;29: 3002-10. DOI: 10.1056/NEJMc1315678
Intrarenal Resistive Index after Renal Transplantation To the Editor: Naesens et al. (Nov. 7 issue)1 published their findings of a well-conducted study looking at the relationship between intrarenal resistive indexes in renal allografts and allograft dysfunction. With regard to the protocolspecified measurements, higher resistive indexes were not associated with allograft dysfunction but were associated with older recipient age and increased mortality. After reading the article, my colleagues and I had a few questions and comments. First, what is the rationale for using a cutoff value of 0.80 to distinguish a lower resistive index from a higher resistive index and for treating the resistive index as a categorical variable when it is in fact a continuous variable? Second, the intraobserver variability and interobserver variability in the study were very low at less than 5% each, but we wonder if this will hold true for the external validity of the results. Third, noninvasive assessment of renal-allograft function is an actively pursued area of investigation in many centers, including ours. In that regard, various 676
types of magnetic resonance imaging (MRI), including blood oxygen level–dependent MRI,2 arterial spin labeling MRI,3 and diffusion-weighted MRI,4 also seem to have shown promising results. Nagaraju Sarabu, M.D., M.P.H. University Hospitals Case Medical Center Cleveland, OH [email protected] No potential conflict of interest relevant to this letter was reported. 1. Naesens M, Heylen L, Lerut E, et al. Intrarenal resistive index
after renal transplantation. N Engl J Med 2013;369:1797-806.
2. Djamali A, Sadowski EA, Muehrer RJ, et al. BOLD-MRI as-
sessment of intrarenal oxygenation and oxidative stress in patients with chronic kidney allograft dysfunction. Am J Physiol Renal Physiol 2007;292:F513-F522. 3. Heusch P, Wittsack HJ, Blondin D, et al. Functional evaluation of transplanted kidneys using arterial spin labeling MRI. J Magn Reson Imaging 2013 October 7 (Epub ahead of print). 4. Abou-El-Ghar ME, El-Diasty TA, El-Assmy AM, Refaie HF, Refaie AF, Ghoneim MA. Role of diffusion-weighted MRI in diagnosis of acute renal allograft dysfunction: a prospective preliminary study. Br J Radiol 2012;85:e206-e211. DOI: 10.1056/NEJMc1315502
n engl j med 370;7 nejm.org february 13, 2014
The New England Journal of Medicine Downloaded from nejm.org at RUTGERS UNIV ALEXANDER LIBRARY on August 11, 2015. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
