99mTc-DTPA scintigraphy in evaluation of acute renal graft complications

1304 Background: Human kidney transplantation is the treatment of choice for advanced chronic renal failure. In the post-transplant period, the most common complications encountered are delayed graft function and acute graft dysfunction due to acute tubular necrosis, rejection, cyclosporine toxicity, urine leak, hematoma, obstruction, lymphocele, renal artery stenosis etc. Although, renal biopsy is the gold standard for diagnosis of most of the complications, it is invasive and can lead to sampling errors or complications. Most of the clinicians prefer one of the non-invasive methods like Ultrasonography (USG), Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and renal scintigraphy. Aim: To evaluate the diagnostic accuracy of 99mTc DTPA for acute renal graft complications. Methods: This study (Prospective observational study) was conducted in the Department of Nuclear Medicine & PET-CT, Sir Ganga Ram Hospital, New Delhi. We included renal transplant patients >18 years with suspected acute graft complications. On 99m Tc DTPA scan, renal perfusion, cortical tracer uptake and drainage pattern were reported by 2 experienced nuclear medicine physicians individually. By this scintigraphy, we diagnosed complications as urine leak, obstruction, hematoma, ATN (Acute tubular necrosis) and AR (Acute rejection). Patients with complications other than AR and ATN were excluded from study. Histopathological reports of the cases were collected and were compared with scintigraphic findings. The patients with AR and ATN on scintigraphy who failed to undergo biopsy were also excluded from study. Results: Between October 2018 and August 2020, 54 patients ( 45 males, 09 females, and mean Age 43.22 ± 9.72 years, Range 19-67 years) underwent renal scintigraphy study in our Nuclear Medicine department with post-transplant complications and in whom kidney biopsy was performed were included in this study. Histopathology reports of all the patients were obtained and correlated with the renal scintigraphy scan findings. Out of 54 patients, renal scintigraphy suggested 39 cases as acute rejection and 15 cases as acute tubular necrosis. Pathological reports of these patients revealed 40 cases as acute rejection and 14 cases as acute tubular necrosis. On correlation of renal scintigraphy and biopsy of all patients, 45 renal scintigraphy reports were concordant with biopsy and 9 reports were discordant. Out of 39 reported as acute rejection, 35 were concordant with biopsy report and 4 were discordant. Out of 15 cases reported as acute tubular necrosis on scintigraphy, 10 were concordant with biopsy and 5 were discordant. Overall, in our study, the sensitivity, specificity and accuracy for detecting AR on renal scintigraphy was found to be 87.5%, 71.43% and 83.33% respectively and the sensitivity, specificity and accuracy for diagnosing ATN were 71.4, 87.5 and 66.67 respectively. Conclusions: 99mTc-DTPA scintigraphy has good diagnostic accuracy for detecting acute graft complications, mainly acute rejection. It is safe, reliable and non-invasive method. It can avoid invasive procedures like biopsy which can cause morbidities. This helps in early diagnosis of complications to start early treatment and help the clinician in making clinical decisions.Key word: Renal transplant, 99mTc-DTPA scintigraphy, diagnostic accuracy