Can Gd-DTPA MR Renography Could be a One Stop Imaging Technique for Assessment of Human Renal Allograft Complications?
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- Category: Vol. 82, June 2014
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Can Gd-DTPA MR Renography Could be a One Stop Imaging Technique for Assessment of Human Renal Allograft Complications?, AHMED A. MAHMOUD, NADINE R. BARSOUM and HANY M. EL-ASSALY
Abstract
Introduction: MRI technique with fast pulse sequences and renal eliminated contrast agent has the capability of combining both anatomic and functional information; having advantages over both computed tomography and nuclear scintigraphy for assessing renal function, because it combines high spatial resolution with information on perfusion and function.
Aim of Work: Evaluate the role of MR Renography in the assessment of renal allograft complications during the post transplantation period.
Subjects and Methods: Thirty nine renal transplant recip-ients (29 males and 10 females), their age range was 18 to 65 years with a mean age of 40±11 years were referred for assessment of deteriorating renal function (31 patients) or other reasons as pain or swelling at the site of the graft, fever or hypertension (8 patients). All patients underwent a full MRI examination, including conventional MR, magnetic resonance angiography (MRA) and magnetic resonance renog-raphy (MRR) examinations. Four patients who had urological complications were examined in addition by MR urography (MRU).
Ultrasound and Doppler studies, renal scan, were also done for all cases. The final diagnosis used for reference was based on graft biopsy (20 cases), constellation of clinical and laboratory data, or clinical response to specific treatment for the other 19 cases.
Results: In the cases of acute rejection in this study, the MRR showed a sensitivity and specificity of 82.2% and 94.6% respectively, ultrasound showed a sensitivity and specificity of 75% and 78.7% respectively, while RNS showed a sensi-tivity and specificity of 80% and 78.9% respectively. MRR in cases of cyclosporine nephrotoxicity showed a sensitivity of 90.7% and a specificity of 92%, ultrasound showed a sensitivity of 70% and a specificity of 79.2%, while RNS showed a sensitivity of 70% and a specificity of 69.7%. Cases with chronic rejection showed 100% sensitivity and specificity by both MRR and RNS, while they showed 92.3% sensitivity and 98.7% specificity by ultrasound and Doppler examinations.
RNS showed high sensitivity in detection of cases of ATN with a sensitivity of 100%, while the two other modalities showed 50% sensitivity in detection of these cases. In ATN as well, the specificity by MRR was 77.1%, by ultrasound was 80.2%, while by RNS was 68.3%. Vascular complications were accurately detected by both Doppler and MRA techniques, yet the Doppler examination provided more details about the velocity and the resistance of the blood flow within the main renal vascular stump as well as the intrarenal vasculature, which could not be quantitatively assessed by MRA studies.
Ultrasound and Doppler are more accurate in detection of urological complications than RNS, where the ultrasound and MRI showed a sensitivity and specificity of 100% for the detection of cases with hydronephrosis as well as their caus-ative agents, while RNS was only sensitive in the detection of hydronephrosis. Also cases with renal stones were detected by ultrasound examination (sensitivity 100%), but neither by MRI or RNS examinations could detect them.
Moreover, in the cases with perinephric collections, both MRI and ultrasound showed sensitivity of 100%, while RNS showed a sensitivity of 51.6%, yet the ultrasound was more specific (80.7% specificity) in detection of the nature of the collection (with the exception of cases of urinomas, where RNS is very specific) as compared with the MRI (46.7% specificity).
Conclusion: A full MRI examination, including conven-tional MRI, MRR, MRA and MRU will give the treating physician and full documented report about the renal allograft morphology and function, which, although expensive and not yet readily available in a lot of medical centers, it provides a one-stop technique for evaluation of almost possible com-plications. However, ultrasound better detects renal stones and vascular complications the Doppler examination provided more details about the velocity and the resistance of the blood flow within the main renal vascular stump as well as the intrarenal vasculature, which could not be quantitatively assessed by MRA studies.
To conclude the combination of ultrasound, Doppler and RNS examinations can give similar results as those given by MRI, yet they are more available, show all possible compli-cations and at a much lower cost for the patient.