Figure 1. (a) A 26-year-old man, 2 years after renal transplantation, presented with uncontrolled hypertension. Shaded-surface display (SSD), anterior view, of subtracted data volume during arterial phase of contrast-enhanced MR angiogram CE-MRA. Typical normal end-to-end anastomosis (arrow) of right internal iliac artery to the donor renal artery. First level branches of the transplant renal artery (arrowheads) are shown. (b) A 58-year-old woman, 1 year after renal transplantation, with uncontrolled hypertension. Coronal-oblique sub-volume maximum-intensity projection (MIP) reconstruction demonstrates a normal end-to-side anastomosis (arrow) of the transplant renal artery to the right external iliac artery. Atherosclerotic irregularity of the luminal outline is depicted, involving the aortic bifurcation and the common and internal iliac arteries. (c) A 46-year-old woman presented with acute pulmonary oedema. SSD, posterior view, of subtracted data volume during venous phase. The transplant renal vein (arrow) and the inferior vena cava (arrowhead) are illustrated. At this time, there is still significant re-circulating contrast medium in the arterial system, which would preclude evaluation of the venous lumen in the region of overlap in an MIP reconstruction. The surface of the enhancing renal parenchyma is also well detailed at these threshold levels for SSD.

Figure 2. A 55-year-old woman, 7 years after renal transplantation, with vascular claudication and uncontrolled hypertension, presented with acute pulmonary oedema. Proximal (native) arterial stenosis was demonstrated as follows. (a) Maximum-intensity projection reconstruction reveals atherosclerotic changes of the distal abdominal aorta and bifurcation, with significant stenosis of the right common iliac artery origin (arrow) and long-segment occlusion of the left common iliac artery. The vascular anastomosis and proximal renal transplant artery are normal. Proximal branches of the transplant renal artery are not well evaluated because of overlap by the external iliac artery. In delayed images the transplant kidney showed poor enhancement. (b) Shaded-surface display image, anterior view, allows confident evaluation of the right common iliac artery origin stenosis (arrow) and the transplant renal artery branches. Digital subtraction angiography was performed with angioplasty and stenting of the right common iliac artery, which permitted control of the hypertension with drugs.

Figure 3. (a) A 7-year old girl, 2 months following renal transplantation, with severe hypertension. Anastomotic stenosis was demonstrated as follows. Sub-volume maximum-intensity projection (MIP) reconstruction shows end-to-end anastomosis of the right internal iliac artery to the transplant renal artery, with significant anastomotic stenosis (arrow) and good enhancement of the distal transplant renal artery and branches. (b) A 12-year-old girl, 2 weeks following renal transplantation, presented with severely deranged renal function. Thrombotic occlusion of the transplant renal artery was demonstrated as follows. Sub-volume coronal-oblique MIP reconstruction reveals occlusion at the anastomotic site (arrow). The renal transplant parenchyma (arrowheads) does not show any enhancement, except for slight linear enhancement of the inner renal parenchyma (compare with native kidney).

Figure 4. A 56-year-old man, 8 years after renal transplantation, developed uncontrolled hypertension. Post-stenotic dilation was demonstrated by maximum-intensity projection reconstruction. End-to-end anastomosis of the transplant renal artery to a short internal iliac artery stump is depicted and also stenosis at the anastomotic site (arrow), with post-stenotic dilation (arrowheads) of the transplant renal artery. Atherosclerotic disease of the iliac arteries is also shown.

Figure 5. (a) A 36-year-old man, 1 year after renal transplantation, presented with uncontrolled hypertension and renal failure. Perfusion defect was demonstrated by thin maximum-intensity projection (MIP) reconstruction. High-grade segmental stenosis (between arrowheads) of the upper pole branch and perfusion defect (arrows) of the upper pole of the transplant kidney are shown. (b) A 10-year-old boy, 3 months following renal transplantation, presented with uncontrolled hypertension. Thin MIP reconstruction reveals a non-enhancing infarct of the upper pole medially (arrows).

Figure 6. A 38-year-old man with a renal transplant presented with uncontrolled hypertension. Extra-renal anastomotic pseudoaneurysm was demonstrated as follows. (a) Sub-volume thin maximum-intensity projection reconstruction shows anastomotic stenosis (arrow) and an associated large pseudoaneurysm (arrowheads). (b) Shaded-surface display image identifiess the pseudoaneurysm (arrowheads) in relation to the anastomotic stenosis (arrow). Angiographic intervention was not possible. Surgical re-anastomosis was performed.

Figure 7. A 10-year-old boy, who received a renal transplant at the age of 2 years, presented with uncontrolled hypertension and renal failure. En-bloc transplant with aortic stump fibrosis was demonstrated as follows. (a) Maximum-intensity projection (MIP) image of the venous phase of CE-MRA shows an overview of the anatomy. Neonatal donor aorta (arrow) and its anastomosis to the common iliac artery (arrowhead), left renal vein (curved white arrow), right renal vein (*), donor inferior vena cava (C) and the inferior vena cava-common iliac vein anastomosis (curved black arrow) are identified. Both transplant kidneys are shown in the right lumbar region. (b) Sub-volume thin MIP reconstruction, arterial phase, reveals anastomosis of the donor abdominal aorta to the external iliac artery (arrowhead), and stenosis at the origins of both transplant renal arteries (arrows), probably due to thrombosis and fibrosis at the level of the distal aortic stump.

Figure 8. A 33-year-old woman, I year following renal transplant, with recent onset of progressive deterioration of renal function. Acute rejection was demonstrated as follows. Coronal-oblique sub-volume maximum-intensity projection image during the venous phase depicts normal end-to-end anastomosis. The transplant renal artery and branches are normal. There is very poor contrast enhancement of transplant renal cortex, minimal enhancement of renal medulla and no contrast excretion from the transplant kidney. At all times, the diseased native kidney showed higher enhancement than the transplant kidney. Both native ureters feature the presence of excreted contrast medium (arrows).

Figure 9. A 43-year-old woman, 3 months after renal transplant, with uncontrolled hypertension. Maximum-intensity projection (MIP) reconstruction artefact was indicated by (a) sub-volume thin MIP image showing near complete anastomotic occlusion (arrow), and (b) selective left internal iliac angiogram revealing 80% stenosis at the anastomotic site (arrow) with good distal flow. Angioplasty and stenting was performed.

Figure 10. A 13-year-old girl, who received a renal transplant 2 years before presentation, developed transplant renal artery anastomotic stenosis, which had previously been dilated with implantation of a self-expanding metallic stent. Follow-up CE-MRA for worsening renal function and increasing hypertension revealed susceptibility artefact due to the metallic stent, as follows. (a) On the maximum-intensity projection image, a long segment of the transplant artery is not identified (between arrows). The distal artery and branches and the renal cortex indicate normal arterial phase enhancement. Patency can, however, be indirectly inferred from enhancement of the artery distal to the apparent complete occlusion. (b) Review of the source images shows susceptibility artefact due to the metallic stent (arrowheads), with contrast medium in the stent lumen (arrow). (c) Digital subtraction angiography confirms patency of the stent (arrowheads).

Figure 11. A 36-year-old man, 5 months after renal transplantation, with uncontrolled hypertension and nephropathy. Susceptibility artefact due to a surgical metallic clip was demonstrated as follows. (a) Maximum-intensity projection image reveals tight stenosis at the anastomotic site (curved arrow). Another segment of apparent stenosis (arrowhead) of the inferior branch of the transplant renal artery and irregularity of the medial wall of the external iliac artery are depicted. (b) Review of the source images revealed an irregular artefactual low signal intensity region (arrowheads) due to the susceptibility artefact from a metallic surgical clip, which resulted in an artefactual narrowing of the inferior branch of the transplant renal artery.

List of diagnoses at CE-MRA: 44 procedures.