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Chronic kidney disease is most desirably and cost-effectively treated by renal transplantation, but graft survival is a major challenge. Although irreversible graft damage can be averted by timely treatment, intervention is delayed when early graft dysfunction goes undetected by standard clinical metrics. A more sensitive and specific parameter for delineating graft health could be the viscoelastic properties of the renal parenchyma, which are interrogated non-invasively by Viscoelastic Response (VisR) ultrasound, a new acoustic radiation force (ARF)-based imaging method. Assessing the performance of VisR imaging in delineating histologically confirmed renal transplant pathologies in vivo is the purpose of the study described here. VisR imaging was performed in patients with (n = 19) and without (n = 25) clinical indication for renal allograft biopsy. The median values of VisR outcome metrics (τ, relative elasticity [RE] and relative viscosity [RV]) were calculated in five regions of interest that were manually delineated in the parenchyma (outer, center and inner) and in the pelvis (outer and inner). The ratios of a given VisR metric for all possible region-of-interest combinations were calculated, and the corresponding ratios were statistically compared between biopsied patients subdivided by diagnostic categories versus non-biopsied, control allografts using the two-sample Wilcoxon test (p 0.05). Although τ ratios non-specifically differentiated allografts with vascular disease, tubular/interstitial scarring, chronic allograft nephropathy and glomerulonephritis from non-biopsied control allografts, RE distinguished only allografts with vascular disease and tubular/interstitial scarring, and RV distinguished only vascular disease. These results suggest that allografts with scarring and vascular disease can be identified using non-invasive VisR RE and RV metrics.

Microbubble ultrasound contrast agents (UCAs) were recently approved by the Food and Drug administration for non-cardiac imaging. The physical principles of UCAs, methods of administration, dosage, adverse effects, and imaging techniques both current and future are described. UCAs consist of microbubbles in suspension which strongly interact with the ultrasound beam and are readily detectable by ultrasound imaging systems. They are confined to the blood pool when administered intravenously, unlike iodinated and gadolinium contrast agents. UCAs have a proven safety record based on over two decades of use, during which they have been used in echocardiography in the U.S. and for non-cardiac imaging in the rest of the world. Adverse effects are less common with UCAs than CT/MR contrast agents. Compared to CT and MR, contrast-enhanced ultrasound has the advantages of real-time imaging, portability, and reduced susceptibility to metal and motion artifact. UCAs are not nephrotoxic and can be used in renal failure. High acoustic amplitudes can cause microbubbles to fragment in a manner that can result in short-term increases in capillary permeability or capillary rupture. These bioeffects can be beneficial and have been used to enhance drug delivery under appropriate conditions. Imaging with a mechanical index of

Malignant renal cell carcinoma (RCC) is a diverse set of diseases, which are independently difficult to characterize using conventional MRI and CT protocols due to low temporal resolution to study perfusion characteristics. Because different disease subtypes have different prognoses and involve varying treatment regimens, the ability to determine RCC subtype non-invasively is a clinical need. Contrast-enhanced ultrasound (CEUS) has been assessed as a tool to characterize kidney lesions based on qualitative and quantitative assessment of perfusion patterns, and we hypothesize that this technique might help differentiate disease subtypes. Twelve patients with RCC confirmed pathologically were imaged using contrast-enhanced ultrasound. Time intensity curves were generated and analyzed quantitatively using 10 characteristic metrics. Results showed that peak intensity ( p = 0.001) and time-to-80% on wash-out ( p = 0.004) provided significant differences between clear cell, papillary, and chromophobe RCC subtypes. These results suggest that CEUS may be a feasible test for characterizing RCC subtypes.

Living donor liver transplantation is emerging as an alternative to cadaveric liver transplantation. The authors present multimodality images obtained in 44 cases of living donor liver transplantation. The images in this article were derived from the pre-, intra-, and postoperative imaging protocol for their institutional transplantation program. Preoperative magnetic resonance (MR) imaging in the donor allows detection of focal liver lesions and accurate determination of liver volume. The latter is crucial to ensure adequate postoperative liver function for donors and recipients. MR cholangiography depicts donor biliary anatomy. MR angiography and digital subtraction arteriography are performed to assess vascular anatomy. Intraoperative ultrasonography (US) helps determine the resection plane during donor hepatectomy. Postoperative MR imaging documents liver regrowth. MR imaging, US, and computed tomography help assess complications in donors and recipients.

To evaluate the ability of Doppler ultrasonography (US) to depict the patency of a transjugular intrahepatic portosystemic shunt (TIPS).Twenty-eight patients were followed up after creation of TIPS with US, angiography, and endoscopy performed at regular intervals. Magnetic resonance (MR) angiography was performed in four patients. US was performed first, and the results were correlated with those at angiography. Measurements of maximum flow velocity (Vmax) were taken from the proximal part of the shunt.In normal shunts, mean Vmax was 95 cm/sec. Shunt obstruction was seen in 12 cases: occlusion in four and stenosis in eight. All cases of occlusion were detected with US and appeared as absent flow within the shunt. There was one false-positive diagnosis of occlusion. All cases of stenosis resulted in reduced Vmax (mean, 32 cm/sec; P.001). After successful revision in seven patients, Vmax rose to a mean of 122 cm/sec. Artifact from the metal stent prevented flow assessment with MR imaging.US can be performed to evaluate shunt status, and Vmax is an accurate noninvasive parameter for assessing shunt patency.

The main risks associated with endoscopic stone removal arise from the sphincterotomy that is performed to facilitate stone extraction. The complication rate may be higher when the bile duct is not dilated. Between January 30, 1990, and March 30, 1993, we attempted to remove stones up to 8 mm in diameter through the intact papilla, without performing sphincterotomy, in 24 patients. Nine patients underwent balloon dilation of the sphincter or of a low duct stricture to facilitate stone removal. All patients were treated successfully and are well at follow-up. Two patients (one having had balloon dilation of the sphincter) had mild pancreatitis that required 2 days in the hospital. During the same period, 215 patients were treated for duct stones 8 mm or less through a standard sphincterotomy. Complications occurred in 11 of these patients: five episodes of pancreatitis, three infections, one perforation, and two other complications. Although these two groups of patients are not directly comparable, it appears that selected stones can be extracted from the bile duct without sphincterotomy with relative safety. This technique should be studied further, especially in younger persons where sphincter preservation may be desirable.