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Renal magnetic resonance angiography with Gd-DTPA in living renal transplant donors
Renal Magnetic Resonance Angiography with Gd-DTPA in Living Renal Transplant Donors A.M. Agildere, N. Uslu Tutar, A. Demirag, F. Boyvat, M. Coskun, and M. Haberal
D
EMONSTRATION of the renal vascular anatomy is a major part of the preoperative evaluation of potential living-related kidney donors, for the safe, uncomplicated removal of the donor allograft.1,2 Accurate determination of number, length, location of renal arteries, the length of the main renal artery proximal to the first parenchymal branch, and identification of accessory renal arteries is essential for proper presurgical planning.1,3 Radiologic evaluation of these patients has traditionally included conventional angiography (CA) and intraarterial digital subtraction angiography (DSA).3,4 These techniques are costly and associated with multiple problems.2 Threedimensional (3D) gadolinium (Gd)-enhanced magnetic resonance angiography (MRA) has been suggested as a potential screening technique owing to its noninvasive nature. In addition to this benefit, it is the most useful technique visualizing renal arteries and smaller vessels in detail due to the use of carefully selected acquisition parameters, suspension of respiration, and correct gadolinium bolus timing.2,5 The purpose of this study was to evaluate the accuracy of Gd-enhanced renal MRA in showing the variations and numbers of renal arteries of potential living-related renal donors before transplantation. SUBJECTS AND METHODS The study group was made up of 29 potential renal transplant donors. Renal arteries were examined using the fast imaging steady precession (FISP) time of flight (TOF) technique in 1.0T magnetic field (Siemens, Expert-Impact, Erlangen) by using body coil. Gd-DTPA was administered intravenously (IV) during a single breath-hold sequence at three phases with a delay time of 15 to 20 seconds. The parameters were as follows: TR: 6.7 msec, TE: 2.8 msec, FA: 30°, TA: 28 msec, AC: 1, matrix size: 140 ⫻ 256, and FOV: 350 ⫻ 350. Postprocessing was made by using a multiple intensity projection (MIP) technique to have reconstructed images from coronal source images. Both source and the reconstructed coronal images were evaluated to demonstrate the number and the variations of renal arteries. DSA was performed on all subjects as a gold standard and these results were compared with MRA.
RESULTS
Renal MRA was successfully carried out on all 29 potential living-related renal donors of age 22 to 65 years. In one individual, technical qualities were suboptimal because of the undesirable effects of excessive venous enhancement
due to the blood circulation time. MRA showed that 21 donors had bilateral single renal arteries. In one of these individuals, a polar branch was visualized on DSA that was not detected using MRA. Four donors had double renal arteries unilaterally (Fig 1A, B), three had a single polar artery unilaterally (Fig 2A, B), and one had single polar branch bilaterally on MRA. In this latter donor, DSA showed another polar branch on the right side feeding the upper pole of the right kidney, a finding that was not demonstrated in MRA. Of these eight subjects, the DSA results of the remaining seven were consistent with MRA results. In one of the individuals who had a single renal artery bilaterally, both MRA and DSA demonstrated early bifurcation of renal arteries on both sides (Fig 3A, B). DISCUSSION
Identification of single or dominant and accessory renal arteries and early bifurcation of renal arteries in the living-related renal donors is important for planning the surgical anastomosis.6,7 Early division of the main renal artery may complicate or even contraindicate surgery as sufficient arterial length must be present to allow for surgical clamping and to provide a sufficient arterial trunk for vascular anastomosis.8 Donors routinely undergo DSA or CA for this assessment.6,7 Although DSA is considered the reference standard for examination of the renal arterial anatomy, this method is not ideal.9 DSA, despite its high spatial resolution, is limited by its planar nature.10 Multiple oblique views may be required in subjects with tortuous arteries, and even then it may not be possible to profile adequately the origins of renal arteries.8 MRA, on the other hand, has a major advantage by viewing the vessels in a full 180° of rotation and by having axial angiographic images that cannot be obtained with DSA methods.10 In general, DSA does not allow the visualization of vessels less than 0.3 mm in diameter. Since accessory vessels less than 1 mm in diameter supply an insignificant portion of the renal parenchyma, preservation of these during the surgery may not be crucial.9 Some studies have shown that accessory vessels or From the Departments of Radiology and General Surgery, Baskent University School of Medicine, Ankara, Turkey. Address reprint requests to A. Muhtesem Agildere, 1. cadde, No:77, Kat:4, Bahc¸elievler 06490, Ankara, Turkey.
© 1999 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
0041-1345/99/$–see front matter PII S0041-1345(99)00809-X
Transplantation Proceedings, 31, 3317–3319 (1999)
3317
3318
AGILDERE, TUTAR, DEMIRAG ET AL
Fig 1. Double renal arteries on the right; MRA (A) and DSA (B) images.
Fig 2. A single polar branch on the left on both MRA (A) and DSA (B) images.
early branches are missed by CA in approximately 8% of patients.9,11 Furthermore, angiographic techniques are costly, invasive, and require the use of nephrotoxic materials.6,7,9 Furthermore, there are systemic or local complications associated with these procedures including bleeding, hematoma, cholesterol emboli, dissection, thrombosis of the femoral artery, contrast reactions, and contrast-related nephrotoxicity.6,7 MRA is a noninvasive easily performed technique without hospitalization or the use of nephrotoxic agents and would therefore be preferable for evaluating the renal arteries in healthy potential donors.6 Techniques used for MRA include TOF, phase contrast
(PC), and contrast-enhanced MRA.5,10,12 The contrastenhanced breath-hold MRA is performed by using 3D gradient acquisition.12 The contrast-enhanced breath-hold sequence MRA entails injection of a large amount of contrast material and yields rapid data acquisition images in a short time, in which arterial enhancement predominates.5,12,13 Infusion of gadolinium chelate contrast material shortens the T1 value of the blood so that it produces high signal while the background produces low signal. Since dynamic Gd-enhanced MRA does not depend on the inflow of unsaturated spins, the saturation problems that complicate routine TOF images are eliminated.12 Other important
RENAL MRA WITH GD-DTPA
3319
decreased morbidity, and reduced cost compared to DSA.1,3,4,6,7,13 In the presurgical evaluation of potential renal donors, contrast-enhanced MRA and DSA provide very similar information. In Low et al’s study,3 on the basis of the results of the DSA and surgical findings, contrast-enhanced MRA enabled correct identification of the arterial supply of all 44 kidneys which included 44 single or dominant renal arteries, 9 accessory renal arteries, and 4 of 5 early arterial branches. In Meyers et al’ study6 with 17 patients, contrast-enhanced MRA showed all single or dominant renal arteries and 8 of 10 accessory arteries that were seen on conventional angiograms. Prince et al13 demonstrated 10 of 11 accessory renal arteries correctly in their study with 63 patients. In our study, MRA and DSA results concurred in 27 patients (93.1%) and MRA enabled successful identification of 69 of total 71 renal arteries with an accuracy rate of 97.1%. Two small polar branches were not shown on MRA. In conclusion, Gd-enhanced MRA without the confounding effects of excessive venous or background tissue enhancement is an accurate and reliable technique for demonstrating the renal artery anatomy of the living-related potential renal transplant donors before transplantation. REFERENCES
Fig 3. Early bifurcation of the renal arteries bilaterally both on MRA (A) and DSA (B) images.
advantages of 3D Gd-enhanced MRA are the lack of nephrotoxicity of the contrast material, the procedure’s noninvasive nature, lack of exposure to iodinated radiation,
1. Debatin JF, Sostman HD, Knelson M, et al: Invest Radiol 28:882, 1993 2. Buzzas GR, Shield III F, Pay NT, et al: Transplantation 64:1734, 1997 3. Low RN, Martinez AG, Steinberg SM, et al: Radiology 207:165, 1998 4. Bakker J, Beek FJA, Beutler JJ, et al: Radiology 207:497, 1998 5. Schoenberg SO, Prince MR, Knopp MV, et al: MRI Clin North Am 6:351, 1998 6. Meyers SP, Talagala SL, Totterman S, et al: Am J Radiol 164:117, 1995 7. Gourlay WA, Yu ¨cel EK, Hakaim AG, et al: Transplantation 60:1363, 1995 8. Platt JF, Ellis JH, Korobkin M, et al: Radiology 198:419, 1996 9. Cochraan ST, Krasny RM, Danovitch GM, et al: Am J Radiol 168:1569, 1997 10. Gedroyc WMW: Urol Clin North Am 21:201, 1994 11. Dachman AH, Newmark GM, Mitchell MT, et al: Am J Radiol 171:193, 1998 12. Borello JA: MRI Clin North Am 5:83, 1997 13. Prince MR, Narasimham DL, Stanley JC, et al: Radiology 197:785, 1995
D
EMONSTRATION of the renal vascular anatomy is a major part of the preoperative evaluation of potential living-related kidney donors, for the safe, uncomplicated removal of the donor allograft.1,2 Accurate determination of number, length, location of renal arteries, the length of the main renal artery proximal to the first parenchymal branch, and identification of accessory renal arteries is essential for proper presurgical planning.1,3 Radiologic evaluation of these patients has traditionally included conventional angiography (CA) and intraarterial digital subtraction angiography (DSA).3,4 These techniques are costly and associated with multiple problems.2 Threedimensional (3D) gadolinium (Gd)-enhanced magnetic resonance angiography (MRA) has been suggested as a potential screening technique owing to its noninvasive nature. In addition to this benefit, it is the most useful technique visualizing renal arteries and smaller vessels in detail due to the use of carefully selected acquisition parameters, suspension of respiration, and correct gadolinium bolus timing.2,5 The purpose of this study was to evaluate the accuracy of Gd-enhanced renal MRA in showing the variations and numbers of renal arteries of potential living-related renal donors before transplantation. SUBJECTS AND METHODS The study group was made up of 29 potential renal transplant donors. Renal arteries were examined using the fast imaging steady precession (FISP) time of flight (TOF) technique in 1.0T magnetic field (Siemens, Expert-Impact, Erlangen) by using body coil. Gd-DTPA was administered intravenously (IV) during a single breath-hold sequence at three phases with a delay time of 15 to 20 seconds. The parameters were as follows: TR: 6.7 msec, TE: 2.8 msec, FA: 30°, TA: 28 msec, AC: 1, matrix size: 140 ⫻ 256, and FOV: 350 ⫻ 350. Postprocessing was made by using a multiple intensity projection (MIP) technique to have reconstructed images from coronal source images. Both source and the reconstructed coronal images were evaluated to demonstrate the number and the variations of renal arteries. DSA was performed on all subjects as a gold standard and these results were compared with MRA.
RESULTS
Renal MRA was successfully carried out on all 29 potential living-related renal donors of age 22 to 65 years. In one individual, technical qualities were suboptimal because of the undesirable effects of excessive venous enhancement
due to the blood circulation time. MRA showed that 21 donors had bilateral single renal arteries. In one of these individuals, a polar branch was visualized on DSA that was not detected using MRA. Four donors had double renal arteries unilaterally (Fig 1A, B), three had a single polar artery unilaterally (Fig 2A, B), and one had single polar branch bilaterally on MRA. In this latter donor, DSA showed another polar branch on the right side feeding the upper pole of the right kidney, a finding that was not demonstrated in MRA. Of these eight subjects, the DSA results of the remaining seven were consistent with MRA results. In one of the individuals who had a single renal artery bilaterally, both MRA and DSA demonstrated early bifurcation of renal arteries on both sides (Fig 3A, B). DISCUSSION
Identification of single or dominant and accessory renal arteries and early bifurcation of renal arteries in the living-related renal donors is important for planning the surgical anastomosis.6,7 Early division of the main renal artery may complicate or even contraindicate surgery as sufficient arterial length must be present to allow for surgical clamping and to provide a sufficient arterial trunk for vascular anastomosis.8 Donors routinely undergo DSA or CA for this assessment.6,7 Although DSA is considered the reference standard for examination of the renal arterial anatomy, this method is not ideal.9 DSA, despite its high spatial resolution, is limited by its planar nature.10 Multiple oblique views may be required in subjects with tortuous arteries, and even then it may not be possible to profile adequately the origins of renal arteries.8 MRA, on the other hand, has a major advantage by viewing the vessels in a full 180° of rotation and by having axial angiographic images that cannot be obtained with DSA methods.10 In general, DSA does not allow the visualization of vessels less than 0.3 mm in diameter. Since accessory vessels less than 1 mm in diameter supply an insignificant portion of the renal parenchyma, preservation of these during the surgery may not be crucial.9 Some studies have shown that accessory vessels or From the Departments of Radiology and General Surgery, Baskent University School of Medicine, Ankara, Turkey. Address reprint requests to A. Muhtesem Agildere, 1. cadde, No:77, Kat:4, Bahc¸elievler 06490, Ankara, Turkey.
© 1999 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
0041-1345/99/$–see front matter PII S0041-1345(99)00809-X
Transplantation Proceedings, 31, 3317–3319 (1999)
3317
3318
AGILDERE, TUTAR, DEMIRAG ET AL
Fig 1. Double renal arteries on the right; MRA (A) and DSA (B) images.
Fig 2. A single polar branch on the left on both MRA (A) and DSA (B) images.
early branches are missed by CA in approximately 8% of patients.9,11 Furthermore, angiographic techniques are costly, invasive, and require the use of nephrotoxic materials.6,7,9 Furthermore, there are systemic or local complications associated with these procedures including bleeding, hematoma, cholesterol emboli, dissection, thrombosis of the femoral artery, contrast reactions, and contrast-related nephrotoxicity.6,7 MRA is a noninvasive easily performed technique without hospitalization or the use of nephrotoxic agents and would therefore be preferable for evaluating the renal arteries in healthy potential donors.6 Techniques used for MRA include TOF, phase contrast
(PC), and contrast-enhanced MRA.5,10,12 The contrastenhanced breath-hold MRA is performed by using 3D gradient acquisition.12 The contrast-enhanced breath-hold sequence MRA entails injection of a large amount of contrast material and yields rapid data acquisition images in a short time, in which arterial enhancement predominates.5,12,13 Infusion of gadolinium chelate contrast material shortens the T1 value of the blood so that it produces high signal while the background produces low signal. Since dynamic Gd-enhanced MRA does not depend on the inflow of unsaturated spins, the saturation problems that complicate routine TOF images are eliminated.12 Other important
RENAL MRA WITH GD-DTPA
3319
decreased morbidity, and reduced cost compared to DSA.1,3,4,6,7,13 In the presurgical evaluation of potential renal donors, contrast-enhanced MRA and DSA provide very similar information. In Low et al’s study,3 on the basis of the results of the DSA and surgical findings, contrast-enhanced MRA enabled correct identification of the arterial supply of all 44 kidneys which included 44 single or dominant renal arteries, 9 accessory renal arteries, and 4 of 5 early arterial branches. In Meyers et al’ study6 with 17 patients, contrast-enhanced MRA showed all single or dominant renal arteries and 8 of 10 accessory arteries that were seen on conventional angiograms. Prince et al13 demonstrated 10 of 11 accessory renal arteries correctly in their study with 63 patients. In our study, MRA and DSA results concurred in 27 patients (93.1%) and MRA enabled successful identification of 69 of total 71 renal arteries with an accuracy rate of 97.1%. Two small polar branches were not shown on MRA. In conclusion, Gd-enhanced MRA without the confounding effects of excessive venous or background tissue enhancement is an accurate and reliable technique for demonstrating the renal artery anatomy of the living-related potential renal transplant donors before transplantation. REFERENCES
Fig 3. Early bifurcation of the renal arteries bilaterally both on MRA (A) and DSA (B) images.
advantages of 3D Gd-enhanced MRA are the lack of nephrotoxicity of the contrast material, the procedure’s noninvasive nature, lack of exposure to iodinated radiation,
1. Debatin JF, Sostman HD, Knelson M, et al: Invest Radiol 28:882, 1993 2. Buzzas GR, Shield III F, Pay NT, et al: Transplantation 64:1734, 1997 3. Low RN, Martinez AG, Steinberg SM, et al: Radiology 207:165, 1998 4. Bakker J, Beek FJA, Beutler JJ, et al: Radiology 207:497, 1998 5. Schoenberg SO, Prince MR, Knopp MV, et al: MRI Clin North Am 6:351, 1998 6. Meyers SP, Talagala SL, Totterman S, et al: Am J Radiol 164:117, 1995 7. Gourlay WA, Yu ¨cel EK, Hakaim AG, et al: Transplantation 60:1363, 1995 8. Platt JF, Ellis JH, Korobkin M, et al: Radiology 198:419, 1996 9. Cochraan ST, Krasny RM, Danovitch GM, et al: Am J Radiol 168:1569, 1997 10. Gedroyc WMW: Urol Clin North Am 21:201, 1994 11. Dachman AH, Newmark GM, Mitchell MT, et al: Am J Radiol 171:193, 1998 12. Borello JA: MRI Clin North Am 5:83, 1997 13. Prince MR, Narasimham DL, Stanley JC, et al: Radiology 197:785, 1995