Visualization of Dialysis Fistula by Computed Tomography Using Time-Resolved 3D Volume Rendering Anders Svensson,1,2 Michael A. Fischer,1,2,3 Kerstin Cederlund,1,2 Peter Aspelin,1,2 Bertil Leidner,1,2 and Torkel B. Brismar,1,2 Stockholm, Sweden; Zurich, Switzerland
Background: To evaluate the function of arteriovenous (AV) dialysis fistula using dynamic computed tomography (CT) and time-resolved 3-dimensional (3D) volume rendering (VR). Methods: Seven patients referred for angiographic CT examination of the AV dialysis fistula were enrolled. Twenty-four grams of iodine were administered intravenously (iomeprol 400 mg I/mL at 6 mL/sec) followed by a 50-mL saline flush. Dynamic scanning was performed for 15e24 sec. CT images were then postprocessed on a dedicated workstation creating timeresolved 3D VR images and movies. Results: All studies showed good image quality showing pathology in 6 of 7 patients. Unexpected findings were observed in 1 patient, aneurysm (n ¼ 1). Radiation dose was 5 mSv. Conclusions: The function of AV dialysis fistula can be visualized using dynamic CT and timeresolved 3D VR.
INTRODUCTION Approximately one-fourth of all US citizens aged older than 60 years have chronic kidney disease, and 1.6 per 1,000 of the whole population has end-stage renal disease. Approximately two-thirds
1 Division of Medical Imaging and Technology, Department of Clinical Science, Intervention and Technology at Karolinska Institutet, Stockholm, Sweden. 2 Department of Radiology, Karolinska University Hospital in Huddinge, Stockholm, Sweden. 3 Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland. Correspondence to: Anders Svensson, RN, Division of Medical Imaging and Technology, Department of Clinical Science, Intervention and Technology at Karolinska Institutet, Stockholm SE-14186, Sweden; E-mail: [email protected]
Ann Vasc Surg 2015; 29: 573–577 http://dx.doi.org/10.1016/j.avsg.2014.08.031 Ó 2015 Elsevier Inc. All rights reserved. Manuscript received: February 24, 2014; manuscript accepted: August 24, 2014; published online: December 2, 2014.
of all patients with end-stage renal disease undergo dialysis.1 An arteriovenous fistula (AVF) is therefore often referred to as ‘‘the lifeline of a patient.’’ There are several variants of native hemodialysis accesses. Radiocephalic fistula, brachiocephalic fistula, and transposed brachiobasilic fistula are among the most frequent accesses. An alternative method to the native access is the use of a synthetic arteriovenous graft. However, this method is considered to be a second-best alternative because of the shorter life span of the synthetic graft. The major cause of hemodialysis access point failure is thrombosis, inadequate maturation, infection, or stenosis. Those are today preferably diagnosed with physical examination, duplex ultrasonography, or angiography. Angiography has a better visualization of the access point and a higher accuracy than duplex ultrasonography, which is user dependent. On the other hand, there is a risk for complications, for example, hematoma associated with angiography, whereas duplex ultrasound is harmless.2e7 573
574 Svensson et al.
Annals of Vascular Surgery
Fig. 1. Three-dimensional postprocessing of an AVF at increasing time points after the contrast media injection.
Lately, the fast development within computed tomography (CT) has opened up entirely new diagnostic possibilities. So-called dynamic scanning has made it possible to perform perfusion and angiographic studies. These techniques are now used in clinical routine for early brain infarction studies.8,9 Dynamic scanning is defined as when an anatomic area is scanned continuously for a predetermined period. When multiple detectors are used, preferably 64 or more, a continuous volume can be imaged with an interval equal to the rotation speed of the scanner (down to 0.3 sec), but when covering greater areas, the patient is moved back and forth in the CT. The interval between each scan sequence is then determined by the size of the area of interest and of the speed of the table movement. By image data postprocessing, it is then possible to play up the rendered images as a movie and to show the inflow of the contrast media (CM) in the vessels (Fig. 1).10 We have investigated whether this technology can be a complement to the currently established methods for the investigation of AVF and vascular anatomy.
MATERIAL AND METHODS All patients are scanned in lateral or prone positioning with the current arm above the head (Fig. 2) using a dual-source 2 64-row
Fig. 2. Lateral positioning.
Vol. 29, No. 3, April 2015
Visualization of dialysis fistula by CT
575
Fig. 3. (A, B) A 3D VR of a cephalic radial fistula (arrows) visualizing the stenosis of the cephalic vein (bottom arrow, A). Follow-up study 6 months later shows a total occlusion of the cephalic vein and multiple generated collateral vessels (B). (C, D) A straightened out view of
the cephalic radial fistula enables direct measurements of the lumen and estimation of the stenosis. At the first examination, the stenosis was estimated to 52% (C), whereas a total occlusion is shown at follow-up examination (D).
multidetector computed tomography equipment (Siemens Somatom Definition Flash; Siemens Healthcare, Forchheim, Germany). Tube voltage is set to 80 kV, and 70-mAs tube currentetime product, 0.28-sec gantry rotation time, and 128 0.6-mm slice collimation are used. A total volume of 60-mL iomeprol, 400 mg I/mL (IomeronÒ-400; Bracco Imaging SpA, Milan, Italy), is administered through a 16-ga peripheral venous access inserted to the antecubital vein of the contralateral arm. A constant injection speed of 6 mL/sec is ensured by using a power injector (Stellant Dual Head Injector; Medrad, Pittsburgh, PA). The CM is immediately followed by a 50-mL saline flush at 6 mL/sec. The delay time from the start of the CM injection until scan start is set to 12 sec, and 5e7 scan repetitions are then obtained depending on the scan range at an interval of 1e3 sec. After the completion of the dynamic examination, the data are reconstructed into 0.6-mm images with an increment of 0.4 mm using kernel B10. All 3-dimensional (3D) volume rendering (VR) and 4-dimensional (4D) postprocessing were made at a separate workstation (Advantage Workstation 4.5; GE Healthcare, Milwaukee, WI).
RESULTS In total, 7 examinations have been performed in 7 patients using time-resolved 3D VR of their AVF. The average radiation dose has been 5 mSv. No complications have been observed. In all patients, the imaging has been successful, showing pathology in 6 patients. In 1 patient, unexpected findings were observed, aneurysm (n ¼ 1).
DISCUSSION To our knowledge, this is the first report of the use of dynamic scanning in visualizing the AVF and its function. From an operator’s technical perspective, dynamic CT examination of a dialysis fistula is a relatively simple procedure. However, correct positioning (Fig. 2) of elderly patients with limited mobility of the arms and shoulders can occasionally be a challenge. The disadvantage of the method is the use of ionizing radiation and intra venous CM. The effective dose for a 481-mm scan range, with 7 repetitions (i.e., time observation points), including ascending aorta through the forearm was calculated to 5 mSv, which is
576 Svensson et al.
Annals of Vascular Surgery
Fig. 4. (A) Angiography of an AVF showing an approximately 5-cm long area with multiple stenosis and occlusion of the brachiocephalic vein. (B, C) The same
pronounced vascular changes are shown at 3D VR, but an axillary aneurysm is also visualized (B). The size of the aneurysm is easily measured (C).
approximately equivalent to a standard thoracic CT examination. The amount of CM, approximately 60 mL, is equivalent to that of a conventional angiography. There are several main advantages of dynamic CT scanning, compared with those of ultrasound and conventional angiography. Compared with ultrasound, the VR data sets provide an excellent anatomic overview. In contrast to angiography,
the images can be freely rotated in any desired plane (Figs. 3-6). These data sets can then be merged into a 4D volume that can be saved as a movie file, which can easily be sent to the referring nephrologist and/ or surgeon. The availability of several different time points of the scanned data allows analysis of both arterial and venous filling. This makes it possible to the clinician to choose the most optimal solution and also simplifies informing the patient about the
Vol. 29, No. 3, April 2015
Visualization of dialysis fistula by CT
577
Fig. 5. Besides, from visualizing the completely occluded cephalic vein the narrowing of the distal radial artery is clearly visualized, potentially affecting surgical plan.
cause of a dysfunctional fistula. It is possible to reconstruct the vessel in the same manner as when performing measurements of the coronary vessels at cardiac imaging (Fig. 3C, D). This makes it possible to accurately estimate vessel and stenosis diameters, enabling later follow-up when evaluating stenosis progress or treatment effect. REFERENCES 1. NIH Publication No. 12e3895, June 2012. 2. Gallieni M, Saxena R, Davidson I. Dialysis access in Europe and North America: are we on the same path? Semin Intervent Radiol 2009;26:96e105. 3. Al-Jaishi AA, Moist L. Fistula eligibility: a work in progress. Semin Dial 2014;27:173e8. 4. Asano M, Thumma M, Oguchi K, et al. Vascular access care and treatment practices associated with outcomes of arteriovenous fistula: international comparison from dialysis outcomes and practice patterns study. Nephron Clin Pract 2013;124:23e30.
Fig. 6. Patient with AV graft with a pronounced stenosis in the transition to the cephalic vein. 5. Vachharajani T. Diagnosis of arteriovenous fistula dysfunction. Semin Dial 2012;25:445e50. 6. Levine M. A challenge for nephrologisteincreasing fistula maturation rates, reducing fistula maturation time, and decreasing dialysis catheter prevalence in the United States. Semin Dial 2008;21:280e4. 7. Beathard G, Arnold P, Jackson J, et al. Aggressive of early fistula failure. Kidney Int 2003;64:1487e94. 8. Dowlatshahi D, Wasserman JK, Momoli F, et al. Evolution of computed tomography angiography spot sign is consistent with a site of active hemorrhage in acute intracerebral hemorrhage. Stroke 2014;45:277e80. 9. Lehmkul L, Andres C, Lucke C, et al. Dynamic CT angiography after abdominal aortic endovascular aneurysm repair: influence of enhancement patterns and optimal bolus timing on endoleak detection. Radiology 2013;268:890e9. 10. Fischer M, Leidner B, Kartalis N, et al. Time-resolved computed tomography of the liver: retrospective, multiphase image reconstruction derived from volumetric perfusion imaging. Eur Radiol 2013;10:330e43.
Background: To evaluate the function of arteriovenous (AV) dialysis fistula using dynamic computed tomography (CT) and time-resolved 3-dimensional (3D) volume rendering (VR). Methods: Seven patients referred for angiographic CT examination of the AV dialysis fistula were enrolled. Twenty-four grams of iodine were administered intravenously (iomeprol 400 mg I/mL at 6 mL/sec) followed by a 50-mL saline flush. Dynamic scanning was performed for 15e24 sec. CT images were then postprocessed on a dedicated workstation creating timeresolved 3D VR images and movies. Results: All studies showed good image quality showing pathology in 6 of 7 patients. Unexpected findings were observed in 1 patient, aneurysm (n ¼ 1). Radiation dose was 5 mSv. Conclusions: The function of AV dialysis fistula can be visualized using dynamic CT and timeresolved 3D VR.
INTRODUCTION Approximately one-fourth of all US citizens aged older than 60 years have chronic kidney disease, and 1.6 per 1,000 of the whole population has end-stage renal disease. Approximately two-thirds
1 Division of Medical Imaging and Technology, Department of Clinical Science, Intervention and Technology at Karolinska Institutet, Stockholm, Sweden. 2 Department of Radiology, Karolinska University Hospital in Huddinge, Stockholm, Sweden. 3 Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland. Correspondence to: Anders Svensson, RN, Division of Medical Imaging and Technology, Department of Clinical Science, Intervention and Technology at Karolinska Institutet, Stockholm SE-14186, Sweden; E-mail: [email protected]
Ann Vasc Surg 2015; 29: 573–577 http://dx.doi.org/10.1016/j.avsg.2014.08.031 Ó 2015 Elsevier Inc. All rights reserved. Manuscript received: February 24, 2014; manuscript accepted: August 24, 2014; published online: December 2, 2014.
of all patients with end-stage renal disease undergo dialysis.1 An arteriovenous fistula (AVF) is therefore often referred to as ‘‘the lifeline of a patient.’’ There are several variants of native hemodialysis accesses. Radiocephalic fistula, brachiocephalic fistula, and transposed brachiobasilic fistula are among the most frequent accesses. An alternative method to the native access is the use of a synthetic arteriovenous graft. However, this method is considered to be a second-best alternative because of the shorter life span of the synthetic graft. The major cause of hemodialysis access point failure is thrombosis, inadequate maturation, infection, or stenosis. Those are today preferably diagnosed with physical examination, duplex ultrasonography, or angiography. Angiography has a better visualization of the access point and a higher accuracy than duplex ultrasonography, which is user dependent. On the other hand, there is a risk for complications, for example, hematoma associated with angiography, whereas duplex ultrasound is harmless.2e7 573
574 Svensson et al.
Annals of Vascular Surgery
Fig. 1. Three-dimensional postprocessing of an AVF at increasing time points after the contrast media injection.
Lately, the fast development within computed tomography (CT) has opened up entirely new diagnostic possibilities. So-called dynamic scanning has made it possible to perform perfusion and angiographic studies. These techniques are now used in clinical routine for early brain infarction studies.8,9 Dynamic scanning is defined as when an anatomic area is scanned continuously for a predetermined period. When multiple detectors are used, preferably 64 or more, a continuous volume can be imaged with an interval equal to the rotation speed of the scanner (down to 0.3 sec), but when covering greater areas, the patient is moved back and forth in the CT. The interval between each scan sequence is then determined by the size of the area of interest and of the speed of the table movement. By image data postprocessing, it is then possible to play up the rendered images as a movie and to show the inflow of the contrast media (CM) in the vessels (Fig. 1).10 We have investigated whether this technology can be a complement to the currently established methods for the investigation of AVF and vascular anatomy.
MATERIAL AND METHODS All patients are scanned in lateral or prone positioning with the current arm above the head (Fig. 2) using a dual-source 2 64-row
Fig. 2. Lateral positioning.
Vol. 29, No. 3, April 2015
Visualization of dialysis fistula by CT
575
Fig. 3. (A, B) A 3D VR of a cephalic radial fistula (arrows) visualizing the stenosis of the cephalic vein (bottom arrow, A). Follow-up study 6 months later shows a total occlusion of the cephalic vein and multiple generated collateral vessels (B). (C, D) A straightened out view of
the cephalic radial fistula enables direct measurements of the lumen and estimation of the stenosis. At the first examination, the stenosis was estimated to 52% (C), whereas a total occlusion is shown at follow-up examination (D).
multidetector computed tomography equipment (Siemens Somatom Definition Flash; Siemens Healthcare, Forchheim, Germany). Tube voltage is set to 80 kV, and 70-mAs tube currentetime product, 0.28-sec gantry rotation time, and 128 0.6-mm slice collimation are used. A total volume of 60-mL iomeprol, 400 mg I/mL (IomeronÒ-400; Bracco Imaging SpA, Milan, Italy), is administered through a 16-ga peripheral venous access inserted to the antecubital vein of the contralateral arm. A constant injection speed of 6 mL/sec is ensured by using a power injector (Stellant Dual Head Injector; Medrad, Pittsburgh, PA). The CM is immediately followed by a 50-mL saline flush at 6 mL/sec. The delay time from the start of the CM injection until scan start is set to 12 sec, and 5e7 scan repetitions are then obtained depending on the scan range at an interval of 1e3 sec. After the completion of the dynamic examination, the data are reconstructed into 0.6-mm images with an increment of 0.4 mm using kernel B10. All 3-dimensional (3D) volume rendering (VR) and 4-dimensional (4D) postprocessing were made at a separate workstation (Advantage Workstation 4.5; GE Healthcare, Milwaukee, WI).
RESULTS In total, 7 examinations have been performed in 7 patients using time-resolved 3D VR of their AVF. The average radiation dose has been 5 mSv. No complications have been observed. In all patients, the imaging has been successful, showing pathology in 6 patients. In 1 patient, unexpected findings were observed, aneurysm (n ¼ 1).
DISCUSSION To our knowledge, this is the first report of the use of dynamic scanning in visualizing the AVF and its function. From an operator’s technical perspective, dynamic CT examination of a dialysis fistula is a relatively simple procedure. However, correct positioning (Fig. 2) of elderly patients with limited mobility of the arms and shoulders can occasionally be a challenge. The disadvantage of the method is the use of ionizing radiation and intra venous CM. The effective dose for a 481-mm scan range, with 7 repetitions (i.e., time observation points), including ascending aorta through the forearm was calculated to 5 mSv, which is
576 Svensson et al.
Annals of Vascular Surgery
Fig. 4. (A) Angiography of an AVF showing an approximately 5-cm long area with multiple stenosis and occlusion of the brachiocephalic vein. (B, C) The same
pronounced vascular changes are shown at 3D VR, but an axillary aneurysm is also visualized (B). The size of the aneurysm is easily measured (C).
approximately equivalent to a standard thoracic CT examination. The amount of CM, approximately 60 mL, is equivalent to that of a conventional angiography. There are several main advantages of dynamic CT scanning, compared with those of ultrasound and conventional angiography. Compared with ultrasound, the VR data sets provide an excellent anatomic overview. In contrast to angiography,
the images can be freely rotated in any desired plane (Figs. 3-6). These data sets can then be merged into a 4D volume that can be saved as a movie file, which can easily be sent to the referring nephrologist and/ or surgeon. The availability of several different time points of the scanned data allows analysis of both arterial and venous filling. This makes it possible to the clinician to choose the most optimal solution and also simplifies informing the patient about the
Vol. 29, No. 3, April 2015
Visualization of dialysis fistula by CT
577
Fig. 5. Besides, from visualizing the completely occluded cephalic vein the narrowing of the distal radial artery is clearly visualized, potentially affecting surgical plan.
cause of a dysfunctional fistula. It is possible to reconstruct the vessel in the same manner as when performing measurements of the coronary vessels at cardiac imaging (Fig. 3C, D). This makes it possible to accurately estimate vessel and stenosis diameters, enabling later follow-up when evaluating stenosis progress or treatment effect. REFERENCES 1. NIH Publication No. 12e3895, June 2012. 2. Gallieni M, Saxena R, Davidson I. Dialysis access in Europe and North America: are we on the same path? Semin Intervent Radiol 2009;26:96e105. 3. Al-Jaishi AA, Moist L. Fistula eligibility: a work in progress. Semin Dial 2014;27:173e8. 4. Asano M, Thumma M, Oguchi K, et al. Vascular access care and treatment practices associated with outcomes of arteriovenous fistula: international comparison from dialysis outcomes and practice patterns study. Nephron Clin Pract 2013;124:23e30.
Fig. 6. Patient with AV graft with a pronounced stenosis in the transition to the cephalic vein. 5. Vachharajani T. Diagnosis of arteriovenous fistula dysfunction. Semin Dial 2012;25:445e50. 6. Levine M. A challenge for nephrologisteincreasing fistula maturation rates, reducing fistula maturation time, and decreasing dialysis catheter prevalence in the United States. Semin Dial 2008;21:280e4. 7. Beathard G, Arnold P, Jackson J, et al. Aggressive of early fistula failure. Kidney Int 2003;64:1487e94. 8. Dowlatshahi D, Wasserman JK, Momoli F, et al. Evolution of computed tomography angiography spot sign is consistent with a site of active hemorrhage in acute intracerebral hemorrhage. Stroke 2014;45:277e80. 9. Lehmkul L, Andres C, Lucke C, et al. Dynamic CT angiography after abdominal aortic endovascular aneurysm repair: influence of enhancement patterns and optimal bolus timing on endoleak detection. Radiology 2013;268:890e9. 10. Fischer M, Leidner B, Kartalis N, et al. Time-resolved computed tomography of the liver: retrospective, multiphase image reconstruction derived from volumetric perfusion imaging. Eur Radiol 2013;10:330e43.
