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Doppler Ultrasonography Before and 6 to 12 Months After Kidney Transplantation
Doppler Ultrasonography Before and 6 to 12 Months After Kidney Transplantation H. Tayebi Khosroshahi, M. Tarzamni, and R. Agajani Oskuii ABSTRACT Introduction. Ultrasound examination of the kidney is relatively inexpensive and provides a way to assess renal location, contour, and size. Doppler ultrasonography is a noninvasive tool for screening renal artery stenosis. It not only provides kidney morphology data, but also describes hemodynamic changes associated with renal artery stenosis, such as increased peak systolic velocity and decreased resistance index (RI). The aim of this study was to compare the Doppler ultrasonographic changes between the donor’s kidney before transplantation and the recipient’s kidney at 6 to 12 months after transplantation. Methods. We compared the results of Doppler ultrasonography in 20 kidney donors and recipients before and 6 to 12 months after transplantation. For this purpose the size, cortical thickness, echogenicity, anastomosis, mean pulsatility index (MPI), and RI of the kidney were recorded in potential donors before transplantation and in recipients at 6 to 12 months after transplantation for statistical analysis. Results. There was more than a 10-mm increase in transplanted kidney length 6 to 12 months after transplantation in 75% of recipients. There was also more than a 10-mm increase in the width of the transplanted kidney in 80% of recipients. There was no significant change in cortical thickness between the donor and the recipient of the kidney. MPI and RI increased slightly after transplantation. There was more than 50% anastomotic stenosis in only 10% of transplanted kidneys. Conclusion. There was significant enlargement of the kidney size with a nonsignificant increase in MPI and RI of the transplanted kidney. Anastomotic stenosis was also less significant in our study.
D
OPPLER ULTRASONOGRAPHY is a noninvasive tool to screen for renal artery stenosis. It not only provides data about kidney morphology, but also describes homodynamic changes associated with renal artery stenosis, such as increased peak systolic velocity (PSV) and decreased resistance index (RI).1 Changes in intrarenal arterial waveforms were shown to be associated with urinary obstruction, several type of intrinsic renal disorders, and renal vascular disease.2 In order to guide proper therapy in the renal transplant patient population, it has become increasingly important to develop noninvasive techniques that reliably detect and discriminate between such allograft complications as obstruction, rejection, cyclosporine tox-
icity, acute tubular necrosis, and infection. Doppler ultrasonography is one such technique; several recent studies have suggested its value in assessing renal transplant dysfunction.3 The aim of this study was to compare the Doppler ultrasonography results of the kidney in the donor before transplantation and in the recipient at 6 to 12 months after transplantation.
From the Imam Hospital, University of Medical Sciences Transplantation Center, Tabriz, Iran. Address reprint requests to H. Tayebi Khosroshahi, Transplantation Center, Imam Hospital, University of Medical Sciences, Tabriz, Iran. E-mail: [email protected]
0041-1345/05/$–see front matter doi:10.1016/j.transproceed.2005.08.003
© 2005 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710
2976
Transplantation Proceedings, 37, 2976 –2981 (2005)
ULTRASONOGRAPHY PRE- AND POSTTRANSPLANTATION
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Table 1. Demographic Data and Results of Kidney Ultrasonography and Doppler Findings, Before and 6 to 12 Months After Kidney Transplantation
Age Male/female Length (mm) Width (mm) Cortex (mm) MPI RI
Donor
Recipient
Difference (P value in paired sample t test)
25.7 ⫾ 4 17/2 112 ⫾ 8.2 43.9 ⫾ 4.6 8.8 ⫾ 1.2 1.00 ⫾ 0.14 0.60 ⫾ 0.05
41.4 ⫾ 15 9/10 118.6 ⫾ 10 53.9 ⫾ 5.9 8.95 ⫾ 1.1 1.00 ⫾ 0.22 0.61 ⫾ 0.08
— — .003 .0001 .725 .322 .932
METHODS In a descriptive and comparative study we compared results of Doppler ultrasonography in 20 kidney donors and recipients. We included kidney allograft recipients from living donors who were on the same immunosuppressive medications with stable graft function. First, gray-scale ultrasonography and color Doppler studies of the potential donor’s kidneys were performed with Hitachi-EUB.525 equipment before kidney transplantation. We recorded kidney size and echogenicity, cortical thickness, and Doppler parameter such as PSV, mean pulsatile index (MPI), RI, and intrarenal flow. Six to 12 months after kidney transplantation all of the above parameters (kidney size, cortical thickness and echogenicity, anastomosis, MPI, RI were analyzed in the transplanted kidney. For accurate evaluation, all ultrasonographic parameters were measured by the same sonologist. Serum creatinine was also measured at the same time as the sonographic evaluation. Then statistical analysis was performed with SPSS11.0 software (paired t test).
RESULTS
The mean age of the potential kidney donors was 25.7 ⫾ 4 years and of recipients, 41.4 ⫾ 15 years. Approximately 90% of kidney donors were men but only 50% of kidney allograft recipients were men. Mean length of kidney was 112 ⫾ 8.2 mm before transplantation and 118.6 ⫾ 10 mm 6 to 12 months after transplantation. Mean kidney width
was 43.9 ⫾ 4.6 mm before transplantation and 53.9 ⫾ 5.9 after 6 to 12 months. There was more than a 6-mm increase in length and about 10 mm in width of the transplanted kidney after 6 to 12 months, which were significant (P ⬍ .01). There was no significant change in cortical thickness of the kidney. Mean MPI and RI were 1.00 ⫾ 0.14 and 0.60 ⫾ 0.05 before transplantation in donors, and 1.00 ⫾ 0.22 and 0.61 ⫾ 0.08 after 6 to 12 months, respectively. The increased mean MPI and RI in the transplanted kidney was not significant. Mean MPI and RI were 1.28 ⫾ 0.05 and 0.72 ⫾ 0.01 in kidney allograft recipients with serum creatinine levels more than 1.8 mg/dL, but was 0.96 ⫾ 0.21 and 0.60 ⫾ 0.08 in those with serum Cr less than 1.8 mg/dL, respectively. In kidney allograft recipients with serum Cr more than 1.8 mg/dL, the mean length of the transplanted kidney was 114 ⫾ 2.8 mm, which was smaller than that in those with serum Cr less than 1.8 mg/dL. There was more than 50% anastomotic stenosis in only 10% transplanted kidneys (Figs 1–7).
DISCUSSION
After renal transplantation, patients are routinely treated with immunosuppressive drugs to minimize the risk of
Fig 1. USP of donor’s kidney (donor 1) before transplantation (length ⫽ 96 mm, width ⫽ 44 mm, cortex ⫽ 8 mm).
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TAYEBI KHOSROSHAHI, TARZAMNI, AND AGAJANI OSKUII
Fig 2.
USP of recipient’s kidney from donor 1 (length ⫽ 112 mm, width ⫽ 50 mm, cortex ⫽ 9 mm).
allograft rejection. Cyclosporine has been widely used for this purpose. There are no distinguished clinical features to differentiate cyclosporine nephrotoxicity from acute
Fig 3.
rejection. At present, the distinction is based on biopsy results. On occasion, even the histology can be nonspecific, with evidence of both toxicity and rejection in a
USP of donor’s kidney (donor 2) before transplantation (length ⫽ 107 mm, width ⫽ 44 mm, cortex ⫽ 8 mm).
ULTRASONOGRAPHY PRE- AND POSTTRANSPLANTATION
Fig 4.
2979
USP of recipient’s kidney from donor 2 (length ⫽ 120 mm, width ⫽ 56 mm, cortex ⫽ 9 mm).
single biopsy. The limitations of conventional sonography prompted the great interest in Doppler evaluation of transplant function.4 Rigsby et al, using a pulsatility index threshold of 1.5, reported a sensitivity of 75% with specificity of 90% in the detection of acute rejection. Rifkin et al found that an RI greater than 0.90 had a 100% predictive value for acute rejection and a value of less than 70% was unlikely to represent rejection.5 Mean RI in our study was 0.60 ⫾ 0.05 in potential donors and was 0.61 ⫾ 0.08 in kidney allograft recipients with stable renal function 6 to 12 months after transplantation.
Mean MPI was also 1.00 ⫾ 0.14 in donors and 1.00 ⫾ 0.22 in transplanted kidney. No other previous study has compared these Doppler parameters between donors and recipients. Kidney size, had also increased in allograft recipients when compared with the donor kidney before transplantation. In conclusion; there was significant enlargement in transplanted kidney size especially in width in our study. There was no significant difference in MPI and RI of the kidney before and after transplantation but MPI and RI were higher in transplanted kidneys with serum Cr more than 1.8 mg/dL.
Fig 5. Other USP of recipient’s kidney from donor 2 (length ⫽ 120 mm, width ⫽ 56 mm, cortex ⫽ 9 mm).
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TAYEBI KHOSROSHAHI, TARZAMNI, AND AGAJANI OSKUII
Fig 6. USP of donor’s kidney before transplantation (length ⫽ 102 mm, width ⫽ 35 mm, cortex ⫽ 10 mm).
Fig 7.
USP of recipient kidney from donor 4 (length ⫽ 130 mm, width ⫽ 51 mm and cortex ⫽ 8 mm).
ULTRASONOGRAPHY PRE- AND POSTTRANSPLANTATION
REFERENCES 1. Bruno S, Ferrari S, Remuzzi G, et al: Doppler ultrasonography in post transplant renal artery stenosis: a reliable tool for assessing effectiveness of revascularization. Transplantation 76:147, 2003 2. Tublin ME, Bude RO, Platt JF: The resistive index in renal doppler sonography. AJR 180:885, 2003
2981 3. Genkins SM, Sanfilippo FP, Carroll BA: Duplex Doppler sonography of renal transplants. AJR 152:535, 1989 4. Buckley AR, Cooperberg PL, Reeve CE, et al: The distinction between acute renal transplant rejection and cyclosporine nephrotoxicity. AJR 149:521, 1987 5. Kelcz F, Pozniak MA, Pirsch JD, et al: Pyramidal apearance and resistive index. Insensitive and nonspecific sonographic indicators of renal transplant rejection. AJR 155:531, 1990
D
OPPLER ULTRASONOGRAPHY is a noninvasive tool to screen for renal artery stenosis. It not only provides data about kidney morphology, but also describes homodynamic changes associated with renal artery stenosis, such as increased peak systolic velocity (PSV) and decreased resistance index (RI).1 Changes in intrarenal arterial waveforms were shown to be associated with urinary obstruction, several type of intrinsic renal disorders, and renal vascular disease.2 In order to guide proper therapy in the renal transplant patient population, it has become increasingly important to develop noninvasive techniques that reliably detect and discriminate between such allograft complications as obstruction, rejection, cyclosporine tox-
icity, acute tubular necrosis, and infection. Doppler ultrasonography is one such technique; several recent studies have suggested its value in assessing renal transplant dysfunction.3 The aim of this study was to compare the Doppler ultrasonography results of the kidney in the donor before transplantation and in the recipient at 6 to 12 months after transplantation.
From the Imam Hospital, University of Medical Sciences Transplantation Center, Tabriz, Iran. Address reprint requests to H. Tayebi Khosroshahi, Transplantation Center, Imam Hospital, University of Medical Sciences, Tabriz, Iran. E-mail: [email protected]
0041-1345/05/$–see front matter doi:10.1016/j.transproceed.2005.08.003
© 2005 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710
2976
Transplantation Proceedings, 37, 2976 –2981 (2005)
ULTRASONOGRAPHY PRE- AND POSTTRANSPLANTATION
2977
Table 1. Demographic Data and Results of Kidney Ultrasonography and Doppler Findings, Before and 6 to 12 Months After Kidney Transplantation
Age Male/female Length (mm) Width (mm) Cortex (mm) MPI RI
Donor
Recipient
Difference (P value in paired sample t test)
25.7 ⫾ 4 17/2 112 ⫾ 8.2 43.9 ⫾ 4.6 8.8 ⫾ 1.2 1.00 ⫾ 0.14 0.60 ⫾ 0.05
41.4 ⫾ 15 9/10 118.6 ⫾ 10 53.9 ⫾ 5.9 8.95 ⫾ 1.1 1.00 ⫾ 0.22 0.61 ⫾ 0.08
— — .003 .0001 .725 .322 .932
METHODS In a descriptive and comparative study we compared results of Doppler ultrasonography in 20 kidney donors and recipients. We included kidney allograft recipients from living donors who were on the same immunosuppressive medications with stable graft function. First, gray-scale ultrasonography and color Doppler studies of the potential donor’s kidneys were performed with Hitachi-EUB.525 equipment before kidney transplantation. We recorded kidney size and echogenicity, cortical thickness, and Doppler parameter such as PSV, mean pulsatile index (MPI), RI, and intrarenal flow. Six to 12 months after kidney transplantation all of the above parameters (kidney size, cortical thickness and echogenicity, anastomosis, MPI, RI were analyzed in the transplanted kidney. For accurate evaluation, all ultrasonographic parameters were measured by the same sonologist. Serum creatinine was also measured at the same time as the sonographic evaluation. Then statistical analysis was performed with SPSS11.0 software (paired t test).
RESULTS
The mean age of the potential kidney donors was 25.7 ⫾ 4 years and of recipients, 41.4 ⫾ 15 years. Approximately 90% of kidney donors were men but only 50% of kidney allograft recipients were men. Mean length of kidney was 112 ⫾ 8.2 mm before transplantation and 118.6 ⫾ 10 mm 6 to 12 months after transplantation. Mean kidney width
was 43.9 ⫾ 4.6 mm before transplantation and 53.9 ⫾ 5.9 after 6 to 12 months. There was more than a 6-mm increase in length and about 10 mm in width of the transplanted kidney after 6 to 12 months, which were significant (P ⬍ .01). There was no significant change in cortical thickness of the kidney. Mean MPI and RI were 1.00 ⫾ 0.14 and 0.60 ⫾ 0.05 before transplantation in donors, and 1.00 ⫾ 0.22 and 0.61 ⫾ 0.08 after 6 to 12 months, respectively. The increased mean MPI and RI in the transplanted kidney was not significant. Mean MPI and RI were 1.28 ⫾ 0.05 and 0.72 ⫾ 0.01 in kidney allograft recipients with serum creatinine levels more than 1.8 mg/dL, but was 0.96 ⫾ 0.21 and 0.60 ⫾ 0.08 in those with serum Cr less than 1.8 mg/dL, respectively. In kidney allograft recipients with serum Cr more than 1.8 mg/dL, the mean length of the transplanted kidney was 114 ⫾ 2.8 mm, which was smaller than that in those with serum Cr less than 1.8 mg/dL. There was more than 50% anastomotic stenosis in only 10% transplanted kidneys (Figs 1–7).
DISCUSSION
After renal transplantation, patients are routinely treated with immunosuppressive drugs to minimize the risk of
Fig 1. USP of donor’s kidney (donor 1) before transplantation (length ⫽ 96 mm, width ⫽ 44 mm, cortex ⫽ 8 mm).
2978
TAYEBI KHOSROSHAHI, TARZAMNI, AND AGAJANI OSKUII
Fig 2.
USP of recipient’s kidney from donor 1 (length ⫽ 112 mm, width ⫽ 50 mm, cortex ⫽ 9 mm).
allograft rejection. Cyclosporine has been widely used for this purpose. There are no distinguished clinical features to differentiate cyclosporine nephrotoxicity from acute
Fig 3.
rejection. At present, the distinction is based on biopsy results. On occasion, even the histology can be nonspecific, with evidence of both toxicity and rejection in a
USP of donor’s kidney (donor 2) before transplantation (length ⫽ 107 mm, width ⫽ 44 mm, cortex ⫽ 8 mm).
ULTRASONOGRAPHY PRE- AND POSTTRANSPLANTATION
Fig 4.
2979
USP of recipient’s kidney from donor 2 (length ⫽ 120 mm, width ⫽ 56 mm, cortex ⫽ 9 mm).
single biopsy. The limitations of conventional sonography prompted the great interest in Doppler evaluation of transplant function.4 Rigsby et al, using a pulsatility index threshold of 1.5, reported a sensitivity of 75% with specificity of 90% in the detection of acute rejection. Rifkin et al found that an RI greater than 0.90 had a 100% predictive value for acute rejection and a value of less than 70% was unlikely to represent rejection.5 Mean RI in our study was 0.60 ⫾ 0.05 in potential donors and was 0.61 ⫾ 0.08 in kidney allograft recipients with stable renal function 6 to 12 months after transplantation.
Mean MPI was also 1.00 ⫾ 0.14 in donors and 1.00 ⫾ 0.22 in transplanted kidney. No other previous study has compared these Doppler parameters between donors and recipients. Kidney size, had also increased in allograft recipients when compared with the donor kidney before transplantation. In conclusion; there was significant enlargement in transplanted kidney size especially in width in our study. There was no significant difference in MPI and RI of the kidney before and after transplantation but MPI and RI were higher in transplanted kidneys with serum Cr more than 1.8 mg/dL.
Fig 5. Other USP of recipient’s kidney from donor 2 (length ⫽ 120 mm, width ⫽ 56 mm, cortex ⫽ 9 mm).
2980
TAYEBI KHOSROSHAHI, TARZAMNI, AND AGAJANI OSKUII
Fig 6. USP of donor’s kidney before transplantation (length ⫽ 102 mm, width ⫽ 35 mm, cortex ⫽ 10 mm).
Fig 7.
USP of recipient kidney from donor 4 (length ⫽ 130 mm, width ⫽ 51 mm and cortex ⫽ 8 mm).
ULTRASONOGRAPHY PRE- AND POSTTRANSPLANTATION
REFERENCES 1. Bruno S, Ferrari S, Remuzzi G, et al: Doppler ultrasonography in post transplant renal artery stenosis: a reliable tool for assessing effectiveness of revascularization. Transplantation 76:147, 2003 2. Tublin ME, Bude RO, Platt JF: The resistive index in renal doppler sonography. AJR 180:885, 2003
2981 3. Genkins SM, Sanfilippo FP, Carroll BA: Duplex Doppler sonography of renal transplants. AJR 152:535, 1989 4. Buckley AR, Cooperberg PL, Reeve CE, et al: The distinction between acute renal transplant rejection and cyclosporine nephrotoxicity. AJR 149:521, 1987 5. Kelcz F, Pozniak MA, Pirsch JD, et al: Pyramidal apearance and resistive index. Insensitive and nonspecific sonographic indicators of renal transplant rejection. AJR 155:531, 1990