Biomedical subjects
C Sommerer
Publications and source records attributed to C Sommerer.
Real-time contrast-enhanced sonography of renal transplant recipients predicts chronic allograft nephropathy.
Real-time contrast-enhanced sonography (RT-CES) can assess microvascular tissue perfusion using gas-filled microbubbles. The study was performed to evaluate the feasibility of RT-CES in detecting chronic allograft nephropathy (CAN) in comparison to color Doppler ultrasonography (CDUS). A total of 26 consecutive renal transplant recipients were prospectively studied using RT-CES and conventional CDUS. Transplant tissue perfusion imaging was performed by low-power imaging during i.v. administration of the sonocontrast Optison. Renal tissue perfusion was assessed quantitatively using flash replenishment kinetics of microbubbles to estimate renal blood flow A *beta (A = peak signal intensity, beta= slope of signal intensity rise). In contrast to conventional CDUS resistance and pulsatility indices, renal blood flow estimated by CES was highly significant related to S-creatinine (r =-0.62, p = 0.0004). Determination of renal blood flow by CES reached a higher sensitivity (91% vs. 82%, p < 0.05), specificity (82% vs. 64%, p < 0.05) and accuracy (85% vs. 73%, p < 0.05) for the diagnosis of CAN as compared to conventional CDUS resistance indices. Perfusion parameters derived from RT-CES significantly improve the early detection of CAN compared to conventional CDUS. RT-CES using low-power real-time perfusion imaging is a feasible method to evaluate microvascular perfusion in renal allograft recipients.
Color Doppler indices of renal allografts depend on vascular stiffness of the transplant recipients.
A resistance index (RI) of 0.8 or higher was shown to be a strong predictor of kidney allograft and patient survival. Uncertainties persist since the intrarenal RI is closely associated with the vascular stiffness of the allograft recipient. To clarify the diagnostic value of RI further, we analyzed parameters of vascular stiffness of the recipient and intrarenal RI of the renal allograft. In a prospective study laboratory and clinical parameters, pulse wave velocity (PWV), intima media thickness (IMT) and RI were obtained in 76 kidney allograft patients. We found that the RI values significantly correlated with the PWV (p < 0.05) and the recipients age (p < 0.01) but not with the donor age and renal function. Using multiple regression analysis recipient age, PWV, pulse pressure (PP) and IMT were identified as independent factors influencing RI values. For a more correct interpretation of the RI values in renal allografts parameters of vascular stiffness such as IMT, PP or PWV should be included.
[Radiologic diagnosis of the kidneys in dialysis patients].
The kidneys of patients with chronic renal failure undergoing maintenance hemodialysis may show different variances or complications. Most common are secondarily acquired renal cysts, which may be found in as many as 92% of patients after 8 years of hemodialysis. Single (in 12.5% of patients) or multiple (8.3%) cysts with bleeding are common; additionally, hematuria or ruptured cysts may be found. Bleeding into cysts is more common in patients with autosomal dominant polycystic kidney disease. Due to the decreasing urinary production development of kidney stones is very uncommon, but calcifications in or around cysts can be found in 71% of patients. Kidney tumors occur 41 times more often in patients with chronic renal failure than in patients without kidney disease. We detected tumors in 4.2% of our patients on long-term dialysis. Diagnostic differentiation of the relatively slow growing and fairly late metastasizing malignant tumors from adenomas is not possible. Nevertheless, we screen our patients every 3-4 years. Computed tomography is superior to ultrasonography for this purpose, because ultrasonography lacks the necessary sensitivity in this group of patients.