APPLICATION OF RADIONUCLIDE DIAGNOSTIC METHODS FOR MONITORING THE FUNCTIONAL CAPACITY OF A TRANSPLANTED KIDNEY: CASE SERIES

Abstract

Introduction. Kidney transplantation represents the optimal treatment for patients with irreversible end-stage renal disease; however, ensuring the long-term functional survival of the allograft remains a critical clinical priority due to the persistent risk of postoperative complications. The standard diagnostic algorithm, including creatinine monitoring and Doppler ultrasonography, often lacks sufficient sensitivity to detect subtle functional impairments at a subclinical stage, while structural imaging and biopsy are limited by the risks associated with contrast exposure, nephrotoxicity, and invasiveness. In this complex diagnostic setting, dynamic renal scintigraphy serves as a non-invasive tool for the physiological assessment of allograft perfusion, filtration, and excretory function.

Aim. To illustrate the capabilities of dynamic renal scintigraphy with 99mTc-DTPA for diagnosing and monitoring the functional status of transplanted kidneys through a series of clinical cases.

Methods. The study presents a case series of four patients aged 19, 23, 26, and 28 years who underwent dynamic renal scintigraphy with the radiopharmaceutical 99mTc-DTPA using a Mediso AnyScan SPECT/CT/PET system. Three patients underwent routine examination one month after transplantation, whereas one patient underwent an emergency examination two weeks after transplantation because of clinical signs of allograft dysfunction. The diagnostic protocol included radionuclide angiography to assess renal blood flow and dynamic renal scintigraphy to evaluate glomerular filtration and excretory function.

Results. The results demonstrated prolongation of the arterial and venous phases of the renangiogram in post-transplant patients, which may reflect physiological postoperative adaptation or mild perfusion impairment. The median estimated glomerular filtration rate was 57.8 mL/min/1.73 m² (range, 21.0-63.0 mL/min/1.73 m²), with a moderate delay in filtration and excretory processes. Notably, the symptomatic patient exhibited a marked deterioration in functional parameters, characterized by severe hypoperfusion and a plateau-shaped renogram curve. These findings prompted urgent allograft biopsy, which morphologically confirmed acute rejection and led to the initiation of targeted immunosuppressive therapy.

Conclusions. This limited case series illustrates that dynamic renal scintigraphy with 99mTc-DTPA can provide useful physiological information on graft perfusion, filtration, and excretion in selected clinical scenarios. Although it cannot replace histological verification or standard monitoring, it may help narrow the differential diagnosis and support clinical decision-making in ambiguous cases. Larger prospective studies are needed to determine its diagnostic accuracy and optimal role in routine allograft surveillance.