CASE REPORT
Graft Kidney Torsion After Simultaneous Kidney-Pancreas Transplant: Report of 2 Cases and Literature Review Keitaro Sofue, MD, PhD,*† Deepak S. Vikraman, MD,‡ Tracy A. Jaffe, MD,* Gaurav N. Chaubal, MD,‡ and Mustafa R. Bashir, MD* Abstract: Torsion of an allograft kidney is an extremely rare and potentially reversible complication. Imaging diagnosis plays a crucial role because of the absence of specific clinical features. We report 2 cases in which kidney torsion after simultaneous kidney-pancreas transplant was diagnosed by ferumoxytol-enhanced magnetic resonance imaging/angiography and present a review of the relevant literature. Radiologists and clinicians should be aware of this entity because graft salvage depends on rapid diagnosis and surgical detorsion. Key Words: kidney transplantation, allograft, torsion, MR angiography, ferumoxytol (J Comput Assist Tomogr 2015;39: 506–509)
A
number of complications can occur after kidney transplantation, including postoperative hemorrhage, transplant artery or vein thrombosis, urine leak, ureteral stricture, and rejection. Allograft torsion is an extremely rare and potentially reversible complication in which the kidney rotates around its vascular pedicle, compromising the vascular supply. Allograft torsion is difficult to diagnose because no specific set of clinical features exists. Presentation typically mimics other more common causes of transplant dysfunction such as rejection, ureteral obstruction, or vascular stenosis or thrombosis. The diagnosis of kidney allograft torsion is frequently delayed because of its nonspecific presentation, even if prompt imaging is performed. Although immediate diagnosis and surgical intervention can salvage allograft function, delayed diagnosis can lead to vascular occlusion and parenchymal infarction, with resulting graft loss. This report describes 2 cases of kidney allograft torsion occurring in intraperitoneal grafts after simultaneous kidney-pancreas transplantation.
CASE 1 A 34-year-old man with end-stage renal disease secondary to type 1 diabetes mellitus underwent intraperitoneal simultaneous kidney-pancreas transplantation (SKPT). Postoperatively, his renal function normalized with a baseline serum creatinine level of 1.1 mg/dL. Three months later, he presented with 2 days of myalgias, low grade fever, and emesis. His serum creatinine was found to be elevated at 4.2 mg/dL. From the *Department of Radiology, Duke University Medical Center, Durham, NC; †Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Japan; and ‡Division of Abdominal Transplantation, Department of Surgery, Duke University Medical Center, Durham, NC. Received for publication February 11, 2015; accepted February 24, 2015. Reprints: Mustafa R. Bashir, MD, Center for Advanced Magnetic Resonance Development, Division of Abdominal Imaging, Duke University Medical Center, Box 3808, 2301 Erwin Rd, Durham, NC 27710 (e‐mail: [email protected]). The authors declare no conflict of interest. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
506
www.jcat.org
A renal transplant ultrasound showed no graft hydronephrosis and no peritransplant fluid collection. Doppler ultrasonography demonstrated abnormal main renal artery waveforms and elevated peak systolic velocities at the anastomosis (Fig. 1A). Although the main renal vein was patent, elevated flow velocities near the venous anastomosis were present (Fig. 1B). Magnetic resonance imaging (MRI) of the pelvis with intravenous ferumoxytol administration 2 days after the ultrasound examination showed that the transplant kidney was located in the midline pelvis and rotated compared with its position on a prior computed tomography (CT) examination (Fig. 1C, D). Dynamic, time-resolved imaging demonstrated a relatively long delay (approximately 16 seconds) between full enhancement of the transplant renal artery and vein (normally 4–8 seconds based on a frame rate of 4 seconds per image volume). The transplant renal vein was wrapped around the artery, with resultant narrowing of both vessels (Fig. 1E). The diagnosis of allograft torsion was made, and the patient was taken to the operating room for emergent exploration. At laparotomy, the presence of graft torsion with marked edema of the kidney was confirmed. Notably, very few adhesions were encountered. The graft was mobilized, detorsed, and fixed to the peritoneum. At follow-up 2 months later, the patient's symptoms had resolved and graft function normalized with serum creatinine of 1.3 mg/dL.
CASE 2 A 37-year-old man who developed end-stage renal disease secondary to type 1 diabetes mellitus underwent intraperitoneal SKPT. Postoperatively, his renal function normalized with a baseline serum creatinine level of 1.3 mg/dL. One month later, he presented for a routine follow-up visit and was found to have an elevated serum creatinine of 7.7 mg/dL, but was asymptomatic. A renal transplant ultrasound demonstrated mild hydronephrosis of the transplant kidney and a small amount of fluid around the transplant kidney. Doppler ultrasonography showed relatively normal waveforms and flow velocities in the transplant main renal artery and vein (Fig. 2A, B). The results of a kidney biopsy showed no evidence of rejection. Magnetic resonance imaging of the pelvis with intravenous ferumoxytol administration 4 days after the ultrasound examination showed that the transplant kidney was located in the midline pelvis and mildly rotated compared with prior CT examination (Fig. 2C, D). Dynamic, time-resolved imaging demonstrated a relatively long delay (approximately 12 seconds) between full enhancement of the transplant renal artery and vein. The transplant renal artery was patent without significant stenosis but crossed over the renal vein, and the vein was severely narrowed in its midportion at the crossing point (Fig. 2E). The possibility of allograft torsion causing venous stenosis was raised based on the MRI, and exploratory laparotomy was performed. J Comput Assist Tomogr • Volume 39, Number 4, July/August 2015
Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Comput Assist Tomogr • Volume 39, Number 4, July/August 2015
Kidney Torsion After Kidney-Pancreas Transplant
FIGURE 1. A, Doppler ultrasonography demonstrates abnormal transplant renal artery waveforms at the main renal artery anastomosis and elevated peak systolic velocity. B, Doppler ultrasonography demonstrates high venous flow velocity near the venous anastomosis. C, A prior coronal contrast-enhanced CT image shows the expected location of the renal allograft laterally in the left lower quadrant (arrow). D, A coronal single-shot fast-spin echo image demonstrates displacement of the allograft into the pelvic midline and rotation compared with prior CT images (arrow). E, A coronal oblique fat-suppressed contrast-enhanced T1-weighted image demonstrates focal narrowing of the transplant renal artery (arrow). The transplant renal vein (arrowhead) wraps around the artery and is also severely narrowed. Figure 1 can be viewed online in color at www.jcat.org.
Intraoperatively, the kidney was found to be engorged and rotated with the renal artery compressing the renal vein. As in the previous case, relatively few adhesions were encountered. The graft was mobilized, detorsed, and fixed to the peritoneum. Postoperatively, the patient's symptoms resolved and graft function was stabilized to a serum creatinine of 1.8 mg/dL.
DISCUSSION The incidence of vascular complications in renal allografts varies from 0.5% to 3.5%; such complications include renal artery stenosis, renal artery thrombosis, renal artery aneurysm, anastomotic hemorrhage, renal vein thrombosis, and allograft torsion.1–3 Graft torsion is extremely rare, with only 22 cases reported in the literature.2–14 Although potentially reversible with prompt surgical intervention, the clinical diagnosis is difficult because presenting symptoms are indistinguishable from more common causes of allograft dysfunction.10 In addition, this complication can occur as early as 1 day postoperatively, or many years later.9,14 Torsion develops as the graft kidney rotates around the renal vascular pedicle and the kidney became trapped under its ureter. Venous stenosis or occlusion typically occurs, which may or may not be accompanied by arterial compromise. In pediatric recipients with Prune-Belly syndrome, preexisting laxity of the abdominal wall, a long vascular pedicle, and excessive fluid in the perinephric space have reported to be risk factors for graft torsion.3–6,14,15 Allograft torsion may be more common with intraperitoneal grafts because intraperitoneal placement allows more mobility than extraperitoneal placement; 13 of 22 reported cases
of allograft torsion have occurred after intraperitoneal placement of SKPT.2,3,6–10,14 In addition, reduced adhesion formation due to certain types of immunosuppression may be a contributing factor.10,14,16 Notably, in our cases, relatively few adhesions were encountered at laparotomy, compared with the robust, firm adhesions typically observed at reexploration of intraperitoneal grafts. Because of the nonspecific clinical manifestations, imaging examinations play a crucial role in the diagnosis of torsion. The most suggestive imaging finding of torsion is a change in orientation of the graft kidney, whose detection can be facilitated by comparison with baseline examinations.3,9 Renal allograft ultrasonography with Doppler imaging is relatively accurate for assessing vascular patency, but it may not specifically detect torsion because the position and axis of the graft can be highly variable among patients.3,15,17 Increased arterial resistive index or reversed venous diastolic flow may be observed in cases of torsion, but can also be seen in acute rejection, urinary obstruction, acute tubular necrosis, other vascular complications, and sometimes in normal cases.3,6,10,13 Computed tomography and MRI are better able to objectively assess for changes in allograft orientation and can detect secondary changes such as edema, graft enlargement, hydronephrosis, and perinephric fluid collections.3,14 Magnetic resonance angiography (MRA) can visualize the vascular pedicle without iodinated or gadolinium-based contrast material.18,19 Recently, ferumoxytol has shown efficacy as an intravascular contrast agent for MRA examinations in patients with severe renal dysfunction. This ironbased contrast agent is not associated with nephrogenic systemic
© 2015 Wolters Kluwer Health, Inc. All rights reserved.
Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
www.jcat.org
507
J Comput Assist Tomogr • Volume 39, Number 4, July/August 2015
Sofue et al
FIGURE 2. A, Doppler ultrasonography demonstrates a normal arterial waveform at the main renal artery with a normal resistive index of 0.87. Arterial peak systolic velocity is at the upper limit of normal. B, Doppler ultrasonography demonstrates that main renal vein is patent with normal velocity in left iliac vein near the venous anastomosis. C, An axial contrast-enhanced CT images immediately after allograft placement shows that the graft is oriented with its long axis in the axial plane (arrow). D, An axial single-shot fast-spin echo image shows that the graft has rotated and now lies with its long-axis oriented vertically (arrow). The graft also appears enlarged compared with the prior CT. E, A coronal fat-suppressed contrast-enhanced T1-weighted image demonstrates severe narrowing of the main renal vein (arrow) at the level where the main renal artery (not shown) crosses. Figure 2 can be viewed online in color at www.jcat.org.
fibrosis unlike gadolinium-based contrast agents, and ferumoxytolenhanced MRA can provide better image quality and reduced flow artifacts compared with noncontrast MRA.20–23 This can be particularly useful in the setting of renal allograft dysfunction because these patients typically present with an estimated glomerular filtration rate less than 20 mg/mL, and the use of both iodinated (CT) and gadolinium-based (magnetic resonance) contrast agents is contraindicated. In addition to demonstrating changes in graft position and orientation, MRA can readily detect resultant venous and arterial stenosis.19,22,23 Surgical detorsion is required for graft salvage. In the existing literature, the rate of immediate graft salvage was 44% after detorsion, and delayed allograft loss occurred in an additional 19% of patients despite restoration of allograft perfusion.10 Given these relatively poor outcomes, when torsion of kidney transplant is suspected, immediate exploratory laparotomy should be considered to avoid irreversible ischemia and graft loss. Nephropexy is typically performed to attach the kidney to the abdominal wall if transplant nephrectomy can be avoided. This procedure prevents future episodes of torsion by reducing graft mobility. However, routine prophylactic nephropexy at the time of graft placement is controversial because it is associated with higher rates of hemorrhage in the setting of postoperative anticoagulation therapy, which is typically undertaken to prevent pancreas graft thrombosis.2,6,10,14 In conclusion, torsion of allograft kidney is an extremely rare and potentially reversible complication. Immediate diagnosis by imaging plays a crucial role in patient management because of the absence of specific clinical features. Although limited data regarding the imaging findings are available because of its rarity, the most suggestive finding of torsion is a change in the axis of the
508
www.jcat.org
transplanted kidney or position. Ferumoxytol-enhanced MRI can be used to evaluate the position and orientation of the graft and to assess vascular patency. Both the radiologist and the clinician should be aware of this entity because graft salvage depends on rapid diagnosis and surgical detorsion.
REFERENCES 1. Dimitroulis D, Bokos J, Zavos G, et al. Vascular complications in renal transplantation: a single-center experience in 1367 renal transplantations and review of the literature. Transplant Proc. 2009;41:1609–1614. 2. Modi P, Pal B, Modi J, et al. Retroperitoneoscopic living-donor nephrectomy and laparoscopic kidney transplantation: experience of initial 72 cases. Transplantation. 2013;95:100–105. 3. Wong-You-Cheong JJ, Grumbach K, Krebs TL, et al. Torsion of intraperitoneal renal transplants: imaging appearances. AJR Am J Roentgenol. 1998;171:1355–1359. 4. Abbitt PL, Chevalier RL, Rodgers BM, Howards SS. Acute torsion of a renal transplant: cause of organ loss. Pediatr Nephrol. 1990;4: 174–175. 5. Marvin RG, Halff GA, Elshihabi I. Renal allograft torsion associated with prune-belly syndrome. Pediatr Nephrol. 1995;9:81–82. 6. West MS, Stevens RB, Metrakos P, et al. Renal pedicle torsion after simultaneous kidney-pancreas transplantation. J Am Coll Surg. 1998;187: 80–87. 7. Roza AM, Johnson CP, Adams M. Acute torsion of the renal transplant after combined kidney-pancreas transplant. Transplantation. 1999;67: 486–488.
© 2015 Wolters Kluwer Health, Inc. All rights reserved.
Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Comput Assist Tomogr • Volume 39, Number 4, July/August 2015
Kidney Torsion After Kidney-Pancreas Transplant
8. Badet L, Petruzzo P, Lefrancois N, et al. Torsion of the renal pedicle after kidney luxation after simultaneous double kidney and pancreas transplantation. Prog Urol. 2003;13:675–678.
16. Dean PG, Lund WJ, Larson TS, et al. Wound-healing complications after kidney transplantation: a prospective, randomized comparison of sirolimus and tacrolimus. Transplantation. 2004;77:1555–1561.
9. Nangia S, Saad ER. Torsion of renal transplant 10 years after simultaneous kidney-pancreas transplantation: imaging as a diagnostic tool. Transplantation. 2009;87:1590.
17. Grenier N, Douws C, Morel D, et al. Detection of vascular complications in renal allografts with color Doppler flow imaging. Radiology. 1991;178: 217–223.
10. Lucewicz A, Isaacs A, Allen RD, et al. Torsion of intraperitoneal kidney transplant. ANZ J Surg. 2012;82:299–302. 11. Winter TC, Clarke AL, Campsen J. Acute torsion of a retroperitoneal renal transplant mimicking renal vein thrombosis. Ultrasound Q. 2013;29: 203–204. 12. Kaynar K, Sonmez B, Kutlu O, et al. A case of recurrent episodes of acute renal allograft failure caused by renal pedicle tortion. Ren Fail. 2013;35: 556–559. 13. Ozmen MM, Bilgic I, Ziraman I, et al. Torsion of extraperitoneally transplanted kidney: an unusual complication. Exp Clin Transplant. 2013; 11:186–190. 14. Sosin M, Lumeh W, Cooper M. Torsion of the retroperitoneal kidney: uncommon or underreported? Case Rep Transplant. 2014; 2014:561506. 15. Plainfosse MC, Calonge VM, Beyloune-Mainardi C, et al. Vascular complications in the adult kidney transplant recipient. J Clin Ultrasound. 1992;20:517–527.
18. Onniboni M, De Filippo M, Averna R, et al. Magnetic resonance imaging in the complications of kidney transplantation. Radiol Med. 2013;118: 837–850. 19. Tang H, Wang Z, Wang L, et al. Depiction of transplant renal vascular anatomy and complications: unenhanced MR angiography by using spatial labeling with multiple inversion pulses. Radiology. 2014;271:879–887. 20. Bashir MR, Bhatti L, Marin D, et al. Emerging applications for ferumoxytol as a contrast agent in MRI. J Magn Reson Imaging. 2015;41:884–898. 21. Fananapazir G, Marin D, Suhocki PV, et al. Vascular artifact mimicking thrombosis on MR imaging using ferumoxytol as a contrast agent in abdominal vascular assessment. J Vasc Interv Radiol. 2014;25:969–976. 22. Bashir MR, Jaffe TA, Brennan TV, et al. Renal transplant imaging using magnetic resonance angiography with a nonnephrotoxic contrast agent. Transplantation. 2013;96:91–96. 23. Bashir MR, Mody R, Neville A, et al. Retrospective assessment of the utility of an iron-based agent for contrast-enhanced magnetic resonance venography in patients with endstage renal diseases. J Magn Reson Imaging. 2014;40:113–118.
© 2015 Wolters Kluwer Health, Inc. All rights reserved.
Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
www.jcat.org
509
Graft Kidney Torsion After Simultaneous Kidney-Pancreas Transplant: Report of 2 Cases and Literature Review Keitaro Sofue, MD, PhD,*† Deepak S. Vikraman, MD,‡ Tracy A. Jaffe, MD,* Gaurav N. Chaubal, MD,‡ and Mustafa R. Bashir, MD* Abstract: Torsion of an allograft kidney is an extremely rare and potentially reversible complication. Imaging diagnosis plays a crucial role because of the absence of specific clinical features. We report 2 cases in which kidney torsion after simultaneous kidney-pancreas transplant was diagnosed by ferumoxytol-enhanced magnetic resonance imaging/angiography and present a review of the relevant literature. Radiologists and clinicians should be aware of this entity because graft salvage depends on rapid diagnosis and surgical detorsion. Key Words: kidney transplantation, allograft, torsion, MR angiography, ferumoxytol (J Comput Assist Tomogr 2015;39: 506–509)
A
number of complications can occur after kidney transplantation, including postoperative hemorrhage, transplant artery or vein thrombosis, urine leak, ureteral stricture, and rejection. Allograft torsion is an extremely rare and potentially reversible complication in which the kidney rotates around its vascular pedicle, compromising the vascular supply. Allograft torsion is difficult to diagnose because no specific set of clinical features exists. Presentation typically mimics other more common causes of transplant dysfunction such as rejection, ureteral obstruction, or vascular stenosis or thrombosis. The diagnosis of kidney allograft torsion is frequently delayed because of its nonspecific presentation, even if prompt imaging is performed. Although immediate diagnosis and surgical intervention can salvage allograft function, delayed diagnosis can lead to vascular occlusion and parenchymal infarction, with resulting graft loss. This report describes 2 cases of kidney allograft torsion occurring in intraperitoneal grafts after simultaneous kidney-pancreas transplantation.
CASE 1 A 34-year-old man with end-stage renal disease secondary to type 1 diabetes mellitus underwent intraperitoneal simultaneous kidney-pancreas transplantation (SKPT). Postoperatively, his renal function normalized with a baseline serum creatinine level of 1.1 mg/dL. Three months later, he presented with 2 days of myalgias, low grade fever, and emesis. His serum creatinine was found to be elevated at 4.2 mg/dL. From the *Department of Radiology, Duke University Medical Center, Durham, NC; †Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Japan; and ‡Division of Abdominal Transplantation, Department of Surgery, Duke University Medical Center, Durham, NC. Received for publication February 11, 2015; accepted February 24, 2015. Reprints: Mustafa R. Bashir, MD, Center for Advanced Magnetic Resonance Development, Division of Abdominal Imaging, Duke University Medical Center, Box 3808, 2301 Erwin Rd, Durham, NC 27710 (e‐mail: [email protected]). The authors declare no conflict of interest. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
506
www.jcat.org
A renal transplant ultrasound showed no graft hydronephrosis and no peritransplant fluid collection. Doppler ultrasonography demonstrated abnormal main renal artery waveforms and elevated peak systolic velocities at the anastomosis (Fig. 1A). Although the main renal vein was patent, elevated flow velocities near the venous anastomosis were present (Fig. 1B). Magnetic resonance imaging (MRI) of the pelvis with intravenous ferumoxytol administration 2 days after the ultrasound examination showed that the transplant kidney was located in the midline pelvis and rotated compared with its position on a prior computed tomography (CT) examination (Fig. 1C, D). Dynamic, time-resolved imaging demonstrated a relatively long delay (approximately 16 seconds) between full enhancement of the transplant renal artery and vein (normally 4–8 seconds based on a frame rate of 4 seconds per image volume). The transplant renal vein was wrapped around the artery, with resultant narrowing of both vessels (Fig. 1E). The diagnosis of allograft torsion was made, and the patient was taken to the operating room for emergent exploration. At laparotomy, the presence of graft torsion with marked edema of the kidney was confirmed. Notably, very few adhesions were encountered. The graft was mobilized, detorsed, and fixed to the peritoneum. At follow-up 2 months later, the patient's symptoms had resolved and graft function normalized with serum creatinine of 1.3 mg/dL.
CASE 2 A 37-year-old man who developed end-stage renal disease secondary to type 1 diabetes mellitus underwent intraperitoneal SKPT. Postoperatively, his renal function normalized with a baseline serum creatinine level of 1.3 mg/dL. One month later, he presented for a routine follow-up visit and was found to have an elevated serum creatinine of 7.7 mg/dL, but was asymptomatic. A renal transplant ultrasound demonstrated mild hydronephrosis of the transplant kidney and a small amount of fluid around the transplant kidney. Doppler ultrasonography showed relatively normal waveforms and flow velocities in the transplant main renal artery and vein (Fig. 2A, B). The results of a kidney biopsy showed no evidence of rejection. Magnetic resonance imaging of the pelvis with intravenous ferumoxytol administration 4 days after the ultrasound examination showed that the transplant kidney was located in the midline pelvis and mildly rotated compared with prior CT examination (Fig. 2C, D). Dynamic, time-resolved imaging demonstrated a relatively long delay (approximately 12 seconds) between full enhancement of the transplant renal artery and vein. The transplant renal artery was patent without significant stenosis but crossed over the renal vein, and the vein was severely narrowed in its midportion at the crossing point (Fig. 2E). The possibility of allograft torsion causing venous stenosis was raised based on the MRI, and exploratory laparotomy was performed. J Comput Assist Tomogr • Volume 39, Number 4, July/August 2015
Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Comput Assist Tomogr • Volume 39, Number 4, July/August 2015
Kidney Torsion After Kidney-Pancreas Transplant
FIGURE 1. A, Doppler ultrasonography demonstrates abnormal transplant renal artery waveforms at the main renal artery anastomosis and elevated peak systolic velocity. B, Doppler ultrasonography demonstrates high venous flow velocity near the venous anastomosis. C, A prior coronal contrast-enhanced CT image shows the expected location of the renal allograft laterally in the left lower quadrant (arrow). D, A coronal single-shot fast-spin echo image demonstrates displacement of the allograft into the pelvic midline and rotation compared with prior CT images (arrow). E, A coronal oblique fat-suppressed contrast-enhanced T1-weighted image demonstrates focal narrowing of the transplant renal artery (arrow). The transplant renal vein (arrowhead) wraps around the artery and is also severely narrowed. Figure 1 can be viewed online in color at www.jcat.org.
Intraoperatively, the kidney was found to be engorged and rotated with the renal artery compressing the renal vein. As in the previous case, relatively few adhesions were encountered. The graft was mobilized, detorsed, and fixed to the peritoneum. Postoperatively, the patient's symptoms resolved and graft function was stabilized to a serum creatinine of 1.8 mg/dL.
DISCUSSION The incidence of vascular complications in renal allografts varies from 0.5% to 3.5%; such complications include renal artery stenosis, renal artery thrombosis, renal artery aneurysm, anastomotic hemorrhage, renal vein thrombosis, and allograft torsion.1–3 Graft torsion is extremely rare, with only 22 cases reported in the literature.2–14 Although potentially reversible with prompt surgical intervention, the clinical diagnosis is difficult because presenting symptoms are indistinguishable from more common causes of allograft dysfunction.10 In addition, this complication can occur as early as 1 day postoperatively, or many years later.9,14 Torsion develops as the graft kidney rotates around the renal vascular pedicle and the kidney became trapped under its ureter. Venous stenosis or occlusion typically occurs, which may or may not be accompanied by arterial compromise. In pediatric recipients with Prune-Belly syndrome, preexisting laxity of the abdominal wall, a long vascular pedicle, and excessive fluid in the perinephric space have reported to be risk factors for graft torsion.3–6,14,15 Allograft torsion may be more common with intraperitoneal grafts because intraperitoneal placement allows more mobility than extraperitoneal placement; 13 of 22 reported cases
of allograft torsion have occurred after intraperitoneal placement of SKPT.2,3,6–10,14 In addition, reduced adhesion formation due to certain types of immunosuppression may be a contributing factor.10,14,16 Notably, in our cases, relatively few adhesions were encountered at laparotomy, compared with the robust, firm adhesions typically observed at reexploration of intraperitoneal grafts. Because of the nonspecific clinical manifestations, imaging examinations play a crucial role in the diagnosis of torsion. The most suggestive imaging finding of torsion is a change in orientation of the graft kidney, whose detection can be facilitated by comparison with baseline examinations.3,9 Renal allograft ultrasonography with Doppler imaging is relatively accurate for assessing vascular patency, but it may not specifically detect torsion because the position and axis of the graft can be highly variable among patients.3,15,17 Increased arterial resistive index or reversed venous diastolic flow may be observed in cases of torsion, but can also be seen in acute rejection, urinary obstruction, acute tubular necrosis, other vascular complications, and sometimes in normal cases.3,6,10,13 Computed tomography and MRI are better able to objectively assess for changes in allograft orientation and can detect secondary changes such as edema, graft enlargement, hydronephrosis, and perinephric fluid collections.3,14 Magnetic resonance angiography (MRA) can visualize the vascular pedicle without iodinated or gadolinium-based contrast material.18,19 Recently, ferumoxytol has shown efficacy as an intravascular contrast agent for MRA examinations in patients with severe renal dysfunction. This ironbased contrast agent is not associated with nephrogenic systemic
© 2015 Wolters Kluwer Health, Inc. All rights reserved.
Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
www.jcat.org
507
J Comput Assist Tomogr • Volume 39, Number 4, July/August 2015
Sofue et al
FIGURE 2. A, Doppler ultrasonography demonstrates a normal arterial waveform at the main renal artery with a normal resistive index of 0.87. Arterial peak systolic velocity is at the upper limit of normal. B, Doppler ultrasonography demonstrates that main renal vein is patent with normal velocity in left iliac vein near the venous anastomosis. C, An axial contrast-enhanced CT images immediately after allograft placement shows that the graft is oriented with its long axis in the axial plane (arrow). D, An axial single-shot fast-spin echo image shows that the graft has rotated and now lies with its long-axis oriented vertically (arrow). The graft also appears enlarged compared with the prior CT. E, A coronal fat-suppressed contrast-enhanced T1-weighted image demonstrates severe narrowing of the main renal vein (arrow) at the level where the main renal artery (not shown) crosses. Figure 2 can be viewed online in color at www.jcat.org.
fibrosis unlike gadolinium-based contrast agents, and ferumoxytolenhanced MRA can provide better image quality and reduced flow artifacts compared with noncontrast MRA.20–23 This can be particularly useful in the setting of renal allograft dysfunction because these patients typically present with an estimated glomerular filtration rate less than 20 mg/mL, and the use of both iodinated (CT) and gadolinium-based (magnetic resonance) contrast agents is contraindicated. In addition to demonstrating changes in graft position and orientation, MRA can readily detect resultant venous and arterial stenosis.19,22,23 Surgical detorsion is required for graft salvage. In the existing literature, the rate of immediate graft salvage was 44% after detorsion, and delayed allograft loss occurred in an additional 19% of patients despite restoration of allograft perfusion.10 Given these relatively poor outcomes, when torsion of kidney transplant is suspected, immediate exploratory laparotomy should be considered to avoid irreversible ischemia and graft loss. Nephropexy is typically performed to attach the kidney to the abdominal wall if transplant nephrectomy can be avoided. This procedure prevents future episodes of torsion by reducing graft mobility. However, routine prophylactic nephropexy at the time of graft placement is controversial because it is associated with higher rates of hemorrhage in the setting of postoperative anticoagulation therapy, which is typically undertaken to prevent pancreas graft thrombosis.2,6,10,14 In conclusion, torsion of allograft kidney is an extremely rare and potentially reversible complication. Immediate diagnosis by imaging plays a crucial role in patient management because of the absence of specific clinical features. Although limited data regarding the imaging findings are available because of its rarity, the most suggestive finding of torsion is a change in the axis of the
508
www.jcat.org
transplanted kidney or position. Ferumoxytol-enhanced MRI can be used to evaluate the position and orientation of the graft and to assess vascular patency. Both the radiologist and the clinician should be aware of this entity because graft salvage depends on rapid diagnosis and surgical detorsion.
REFERENCES 1. Dimitroulis D, Bokos J, Zavos G, et al. Vascular complications in renal transplantation: a single-center experience in 1367 renal transplantations and review of the literature. Transplant Proc. 2009;41:1609–1614. 2. Modi P, Pal B, Modi J, et al. Retroperitoneoscopic living-donor nephrectomy and laparoscopic kidney transplantation: experience of initial 72 cases. Transplantation. 2013;95:100–105. 3. Wong-You-Cheong JJ, Grumbach K, Krebs TL, et al. Torsion of intraperitoneal renal transplants: imaging appearances. AJR Am J Roentgenol. 1998;171:1355–1359. 4. Abbitt PL, Chevalier RL, Rodgers BM, Howards SS. Acute torsion of a renal transplant: cause of organ loss. Pediatr Nephrol. 1990;4: 174–175. 5. Marvin RG, Halff GA, Elshihabi I. Renal allograft torsion associated with prune-belly syndrome. Pediatr Nephrol. 1995;9:81–82. 6. West MS, Stevens RB, Metrakos P, et al. Renal pedicle torsion after simultaneous kidney-pancreas transplantation. J Am Coll Surg. 1998;187: 80–87. 7. Roza AM, Johnson CP, Adams M. Acute torsion of the renal transplant after combined kidney-pancreas transplant. Transplantation. 1999;67: 486–488.
© 2015 Wolters Kluwer Health, Inc. All rights reserved.
Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Comput Assist Tomogr • Volume 39, Number 4, July/August 2015
Kidney Torsion After Kidney-Pancreas Transplant
8. Badet L, Petruzzo P, Lefrancois N, et al. Torsion of the renal pedicle after kidney luxation after simultaneous double kidney and pancreas transplantation. Prog Urol. 2003;13:675–678.
16. Dean PG, Lund WJ, Larson TS, et al. Wound-healing complications after kidney transplantation: a prospective, randomized comparison of sirolimus and tacrolimus. Transplantation. 2004;77:1555–1561.
9. Nangia S, Saad ER. Torsion of renal transplant 10 years after simultaneous kidney-pancreas transplantation: imaging as a diagnostic tool. Transplantation. 2009;87:1590.
17. Grenier N, Douws C, Morel D, et al. Detection of vascular complications in renal allografts with color Doppler flow imaging. Radiology. 1991;178: 217–223.
10. Lucewicz A, Isaacs A, Allen RD, et al. Torsion of intraperitoneal kidney transplant. ANZ J Surg. 2012;82:299–302. 11. Winter TC, Clarke AL, Campsen J. Acute torsion of a retroperitoneal renal transplant mimicking renal vein thrombosis. Ultrasound Q. 2013;29: 203–204. 12. Kaynar K, Sonmez B, Kutlu O, et al. A case of recurrent episodes of acute renal allograft failure caused by renal pedicle tortion. Ren Fail. 2013;35: 556–559. 13. Ozmen MM, Bilgic I, Ziraman I, et al. Torsion of extraperitoneally transplanted kidney: an unusual complication. Exp Clin Transplant. 2013; 11:186–190. 14. Sosin M, Lumeh W, Cooper M. Torsion of the retroperitoneal kidney: uncommon or underreported? Case Rep Transplant. 2014; 2014:561506. 15. Plainfosse MC, Calonge VM, Beyloune-Mainardi C, et al. Vascular complications in the adult kidney transplant recipient. J Clin Ultrasound. 1992;20:517–527.
18. Onniboni M, De Filippo M, Averna R, et al. Magnetic resonance imaging in the complications of kidney transplantation. Radiol Med. 2013;118: 837–850. 19. Tang H, Wang Z, Wang L, et al. Depiction of transplant renal vascular anatomy and complications: unenhanced MR angiography by using spatial labeling with multiple inversion pulses. Radiology. 2014;271:879–887. 20. Bashir MR, Bhatti L, Marin D, et al. Emerging applications for ferumoxytol as a contrast agent in MRI. J Magn Reson Imaging. 2015;41:884–898. 21. Fananapazir G, Marin D, Suhocki PV, et al. Vascular artifact mimicking thrombosis on MR imaging using ferumoxytol as a contrast agent in abdominal vascular assessment. J Vasc Interv Radiol. 2014;25:969–976. 22. Bashir MR, Jaffe TA, Brennan TV, et al. Renal transplant imaging using magnetic resonance angiography with a nonnephrotoxic contrast agent. Transplantation. 2013;96:91–96. 23. Bashir MR, Mody R, Neville A, et al. Retrospective assessment of the utility of an iron-based agent for contrast-enhanced magnetic resonance venography in patients with endstage renal diseases. J Magn Reson Imaging. 2014;40:113–118.
© 2015 Wolters Kluwer Health, Inc. All rights reserved.
Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
www.jcat.org
509
