Gray Scale Ultrasonic Appearances of Renal Transplant Rejection

Abstract

Ultrasonic examination of renal transplants with special attention to the parenchymal echo pattern has been undertaken in 43 patients. In the normal renal transplant, the pyramids, cortex and renal sinus can be distinguished. Renal transplant rejection is manifested by swelling and decreased echogenicity of the pyramids and hyperechogenic cortex. In addition, large anechoic areas due to hemorrhagic infarcts and necrosis are seen. In long-standing rejection, a normal or small-sized kidney with an irregular intrarenal echo pattern is observed. In 13 cases of acute tubular necrosis, none of the above appearances could be demonstrated. Serial ultrasonic scans are essential to reveal evolutionary changes of the rejection process.

Further observations in the ultrasound evaluation of renal allograft rejection.

“…Enlarged pyramids of decrea .ed echogenicity represent the edema, congestion and hemorrhage of the interstitial tissue. 9 Hyperechogenicity of the cortex is t!1ought to l?e related to ischemia and cellular infiltration of the cortex, usually by small lymphocytes and plasma cells. 1 The patchy anechoic areas within the parenchynm are folt to be clue to necrosis and liquefaction.…”

“…1 The patchy anechoic areas within the parenchynm are folt to be clue to necrosis and liquefaction. 9 The distortion of the renal outline and compression of the renal sinus echoes reflects the generalized edema, cellular infiltration, and vascular congestion of the rejecting renal allograft. 1 • 9 Hricak has provided an elegant description of the specific changes involving the renal sinus structures in acute rejection which do not rely upon compression from altered adjacent renal parenchyma hut rather reflect the primary rejection process of the structures found there.…”

Ultrasonographic Evaluation of Renal Size in Dogs With Acute Allograft Rejection

“…LTRASONOGRAPHY HAS BEEN widely used in humans to U monitor renal transplants for evidence of rejection. In early studies qualitative changes such as increased cortical echogenicity , ' ,' hypoechogenicity of the renal medulla, [1][2][3] indistinctness of the corticomedullary j~n c t i o n ,~ and decreased renal sinus echoes4 were described as signs indicative of rejection. Quantitative measurements of cortical and medullary enlargement, increased renal diameter,"' ~o l u m e , ' -~~~* ' and Doppler measurements of the resistive index (RI)'*-I4 have also been used to evaluate kidney rejection.…”