Renal transplant imaging

Renal transplant imaging - radiology update

1. IMAGING IN RENAL TRANSPLANT……

2. Incidence of ESRD is rising. the most desirable treatment  Renal transplant. Sources of donor kidneys Cadavers Living donors.

3. Depends on Immunosuppression . HLA matching. Transplant team. Ideal recipient age ( 5- 50 years). 90-95% of recipients survive the first year of surgery with at least 80 % of them functioning at that time. Results of RT

4. Despite careful selection and management of patients only a minority of kidneys retain function useful than 10 years. Patients may receive subsequent grafts after a first one has failed ,and the duration of function of the first graft is a useful predictor of the longevity of the next transplantation

5. Selection of donors and recipients. Detection and management of post-transplant complications. Radiology in transplant.

6. PRE TRANSPLANT EVALUATION

7. Living donor evaluation

8. 20 %. HLA matching  Radiological evaluation. To rule out morphological/vascular abnormalities of donor kidney. Remaining kidney is sufficiently normal – donor should not be at risk for subsequent renal insufficiency.

9. Laparoscopic nephrectomy. CT is the preferred imaging due to better spatial resolution and sensitivity to vascular calcifications and renal stones. CTA >> MRA Distinguishing single/two main renal arteries. Anatomy and to identify the point at which first branch occurs. Renal venous anatomy, Tiny polar accessory arteries.

10. RENAL ARTERY Origin : from the abdominal aorta at the L1-2 vertebral body level, inferior to the origin of the  superior mesenteric artery .  Course The right renal artery courses inferiorly and passes posterior to the  IVC  and the right  renal vein  to reach the renal hilum. The left renal artery is much shorter and arises slightly more superior to the right main renal artery. The left renal artery courses more horizontally, posterior to the left renal vein to enter the renal hilum. Renal arteries are 4-6 cm in length and 5-6 mm in diameter .

11. Branches Each renal artery gives off small branches in its proximal course, prior to dividing into dorsal and ventral rami . inferior adrenal artery ureteric artery capsular artery The dorsal and ventral rami  segmental branches within the renal hilum before entering the parenchyma {apical, anterior superior, anterior inferior (middle), inferior and posterior segmental renal arteries}  lobar branches  interlobar , arcuate , and interlobular arteries. The afferent arterioles, which supply the  glomeruli , originate from the interlobular arteries.

12. Doppler ultrasound normal PSV 150-180 cm/s and beyond this ,indicate a renal artery stenosis of >60%  . Normal RI ≈ 0.60 Variant anatomy accessory renal arteries: aberrant renal arteries: enter via the renal capsule rather than the hilum early branching (or prehilar branching): occurs within 1.5-2.0 cm of origin in the left renal artery or in the retrocaval segment of the right renal artery important to recognize in renal transplant for successful anastomoses Radiographic features

13. NECT Calculi /vascular calcification Arterial phase Vascular supply Delayed image Collecting system

14. I. Assessment of Renal Volume:- Main predictor of renal function. Larger kidneys :- Remaining kidney:- better renal function. Donor kidney :- Fewer complication in recipient. Contraindication Tumors Post inflammatory fibrosis Hydronephrosis. Any medical condition affecting health of recipient/donor. Small renal stones/cortical cyst – not really a contraindication Evaluation of the kidneys …

15. Atherosclerosis. FMD Accessory renal artery. Duplicated renal artery. Triplicated renal artery. Occluded small lower polar arteries. Short distance between the origin and first bifurcation of all major renal arteries. II.Renal vascular assessment.

16. Renal venous anatomy Retro-aortic/circum-aortic left renal vein. Duplicated right renal veins Distance between junction of vein with IVC and first bifurcation Renal venous tributaries: adrenal/lumbar/ gonadal veins.

17. Left kidney is preferred for donation. Left renal vein is longer and surgical resection is easier. Single renal artery is preferred. Donor kidney with lower pole accessory artery is avoided. Peri-renal fat is usually removed before transplantation. Points to remember.

18. Solitary kidney, Horse shoe kidney Polycystic kidney disease Contraindications to transplantation,

19. Recipient evaluation

20. Heterotopic renal transplantation. Donor kidney is placed in an extra peritoneal location in iliac fossa. Renal artery and vein is anastomosed to external iliac vessels Urinary tract is reconstructed by an anti-refluxing urterneocystostomy .

21. USG/CT/MRI/Radionuclide studies. Specific imaging – Voiding Cystourethrography . Evaluation of vessels is by NECT Assess the degree of calcification = Degree of difficulty in performing the anastomosis. ESRD , usually undergo biopsy  AVF/pseudo-aneurysm .

22. COMPLICATIONS OF RENAL TRANSPLANATION

23. Renal parenchymal Renal vascular Urologic Fluid collections Complications

24. Temporal Sequence of Causes of Parenchymal Complications of Renal Transplants

25. immediately after transplantation. Due to ischemia of the transplanted kidney before vascular anastomosis. Occur in cadaveric donors during the agonal period of the donor and in any donor kidney during the delay between the harvesting of the kidney and the completion of vascular anastomoses in the recipient. Duration of the ischemia is directly related to the likelihood of ATN. resolve spontaneously and have little adverse effect on ultimate graft survival 1.Acute Tubular Necrosis

26. Manifest as anuria , rising creatinine, and mild enlargement and tenderness of the graft. Graft tenderness and fever are less likely to be prominent signs of ATN than of cases of acute rejection, but the clinical picture seldom allows confident differentiation between the two conditions. ATN usually appears within ½ days after transplantation and usually resolves within a few days to a few weeks of initial onset; Patients who experience ATN after transplantation may require dialysis for a week until renal function returns. ATN is much more common in cadaveric transplants than living related donors

27. Cyclosporine,+ prednisone, Nephrotoxic & hepatotoxic . Newer drugs, sirolimus , tacrolimus , and mycophenolate mofetil ,permit reduction in doses of cyclosporine and diminished nephrotoxicity at the cost of increased risk of hyperlipidemia and diabetes. Cyclosporine nephrotoxicity  acute, subacute , or chronic. Acute toxicity potentiate and prolong the graft dysfunction due to iscahemia . 2.Cyclosporine Nephrotoxicity

28. (1) hyperacute rejection, (2) accelerated acute rejection, (3) acute rejection (4) chronic rejection.   Differentiation of graft rejection from other causes of intrinsic renal dysfunction is crucial because rejection may require increasing the dose of immunosuppressive therapy 3.Rejection

29. 1o weeks

30. Hyperacute rejection Doppler usg shows little or nil cortical blood flow Radionuclide studies show complete absence of perfusion or tubular accumulation Angiography : total or near total lack of filling of vessels.

31. Accelerated acute rejection demonstrates imaging findings consistent with acute rejection, but occurs within the first week after transplantation. Rare cases of cortical nephrocalcinosis (Fig.9.12) have been described in patients whose transplants underwent severe immediate rejection but were left insitu for several years.

32. On a grey scale : With acute transplant rejection may show an increase in the volume of the kidney Swelling Altered echogenicity of the renal pyramids and the cortex. The high echogenicity of the sinus of a normal kidney may be diminished. These findings are thought to reflect edema of the parenchyma and of the renal sinus fat. Edema of the collecting system walls may make them appear thickened. The sensitivity of these findings to diagnose rejection, however, and the ability to distinguish rejection from cyclosporine nephrotoxicity and ATN when the findings are not clearly present are poor

33. Diminution in blood flow Rejection. Cyclosporine nephrotoxicity. ATN. If RI > 0.9  Acute rejection. If PI > 1.5  rejection. In ATN = higher RI/PI indicates longer period of recovery.

34. RI and PI have prognostic significance also. If they remain elevated in first transplant month  increased risk for chronic allograft nephropathy. Elevated RI  increased risk for subsequent development or worsening of general CVD. And also indicates decreased compliance of systemic arteries in the body.

35. Graft recipient >>> donor… Incidence and severity rely on dose of immunotherapy DM Co- existant graft dysfunction. Organisms:- Gram negative pathogens/CMV/HSV. 4.Graft infection

36. Unusual complication. First 2 weeks of transplant surgery. Predisposing causes :- Acute rejection. ATN, vascular occlusion. Imaging Renal parenchymal laceration Intra-renal hematoma Peri-renal hematoma. USG:- hypoechoic fluid collection represents a hematoma within the laceration/peri-nephric space. CT:- dense clot within the laceration/peri-nephric space. 4.Renal transplant Rupture..

37. 1.Thrombosis. Immediate post-operative period. Due to complete/partial occlusion at the anastamotic site or result of an intimal flap. Vascular complications

38. No flow in the inferior portion of the transplanted kidney Little isotope in the same region

39. 2.Renal artery stenosis. Mc vascular complication reduced renal function; htn ; a bruit. @ host artery proximal to anastomosis  related to atherosclerosis or trauma at time of surgery. @ anastomotic site  Surgical technique , suture material , perfusion injury of vessels. Post anastomotic site :- refection , abnormal local hemodynamics , extrinsic compression. Require arterial imaging for accurate complication either with USG doppler , CTA/MRA. Percutaneous Transluminal angioplasty is the preferred mode of treatment

40. Transplant artery stenosis with MRA.

41. 3. Renal AVF

42. Urinary leak Ureteral necrosis Ureteral obstruction Torsion III.Urologic complications

43. URINARY LEAK

44. URETERAL NECROSIS

45. URTERAL OBSTRUCTION

46. Hematoma Urinomas Lymphocele Abscess IV. Fluid collections

47. Increased risk of malignancy in post RT patients. Related to the dose and duration of the immunosuppressive drugs. Lymphoprolefeative disorders(PTLD):- esp in patients with EBV. Renal cell carcinoma (2 %):- 1oo times increased risk and most common cell type is Papillary carcinoma. Lymphoma. Neoplasms