Purpose To retrospectively determine the incidence of nephrogenic systemic fibrosis (NSF) in patients on dialysis administered either a lower dose high-relaxivity linear gadolinium-chelate, gadobenate dimeglumine (Multi-Hance, MH), compared to a standard dose linear gadolinium chelate, gadodiamide (Omniscan, OM). Materials and Methods This study was Health Insurance Portability and Accountability Act (HIPAA)-compliant and Institutional Review Board (IRB)-approved. As per institution standardized contrast-enhanced magnetic resonance imaging (MRI) protocols, patients on dialysis were imaged using either MH, between 2/2007 to 9/2008, or OM between 10/2003 and 1/2007. Rates of NSF were compared using 95% score-based confidence intervals (CI). The Wilcoxon rank sum test was used to test similarity/difference between contrast doses given to each patient group. Results Overall, 312 patients on dialysis received OM and eight (2.6%) developed NSF (95% CI: 1.30%–4.98%). In all, 784 patients on dialysis received MH at a mean cumulative dose of 0.11 mmol/kg (0.05–0.75 mmol/kg) and no cases of NSF were identified (upper 95% confidence bound of 0.45%). The mean cumulative dose of OM was 0.16 mmol/kg (0.1–0.9 mmol/kg) for all patients and 0.28 mmol/kg (0.1–0.8 mmol/kg) for the patients with NSF. The median OM dose was greater in patients who developed NSF (P = 0.03), and was greater than the median MH dose (P < 0.005). Conclusion NSF incidence in at-risk patients receiving contrast-enhanced MRI can be reduced after changing contrast administration protocols that includes changing the type and dose of contrast agent.

Purpose: To retrospectively analyze nephrogenic systemic fibrosis (NSF) cases at our center, to determine prior gadolinium based contrast agent (GBCA) administration and to evaluate possible common risk factors for the development of NSF by reviewing laboratory data and concurrent medications. Materials and Methods:A total of four data bases (pathology, MRI, dialysis, and medical records) were crossreferenced for identification and evaluation of NSF patients. Medical history of NSF patients was assessed as for previous deep venous thrombosis (DVT), surgery, or infections. Laboratory data (creatinine, anion gap, calcium, phosphorus, and albumin) as well as concurrent medication were evaluated. Findings were compared to those of a control group of non-NSF dialysis patients.Results: Between October 2003 and February 2007 a total of nine NSF cases were identified. All patients had undergone contrast-enhanced MRI prior to the diagnosis of NSF. Only one gadolinium chelate had been used at our MRI center (Omniscan, gadodiamide; GE Healthcare). Of nine patients, eight were receiving dialysis at the time of the MRI scan. During the same time 312 dialysis patients received gadodiamide. Thus, the prevalence of NSF within dialysis patients exposed to gadodiamide was 2.6%. NSF patients presented with a higher creatinine and anion gap than the control patients. Other laboratory values as well as medication did not show a significant difference. There were no patterns regarding previous history of DVT, surgery, or infection in the NSF group. Conclusion:Our findings are consistent with the previously reported association between gadodiamide exposure and NSF. All NSF patients had severe renal insufficiency with glomerular filtration rate (GFR) Ͻ 30 (highest GFR ϭ 25 mL/minute) at the time of last gadodiamide administration, and on average had received 71 mL of gadodiamide over an average of 2.9 administrations.

Contrast-enhanced MRI can be used as a primary diagnostic method for accurate detection and characterization of HCC 2 cm or larger as required by the criteria of the Model for End-Stage Liver Disease used by the United Network for Organ Sharing. MRI can be considered a standard tool for surveillance before liver transplantation. Reduction in cost and risk may be derived from the diminished need for other diagnostic imaging studies and biopsy and the avoidance of use of iodinated contrast agents in imaging of patients with cirrhosis, many of whom have impaired renal function.

Purpose: To measure contrast agent enhancement kinetics in the liver and to further evaluate and develop an optimized gadolinium enhanced MRI using a single injection real-time bolus-tracking method for reproducible imaging of the transient arterial-phase. Materials and Methods:A total of 18 subjects with hypervascular liver lesions were imaged with four dimensional (4D) perfusion scans to measure time-to-peak (TTP) delays of arterial (aorta-celiac axis), liver parenchyma, liver lesion, portal, and hepatic veins. Time delays were calculated from the TTP-aorta signal, and then related to the gradient echo (GRE) k-space acquisition design, to determine optimized timing for real-time bolus-track triggering methodology. As another measure of significance, 200 clinical patients were imaged with 3D-GRE using either a fixed time-interval or by individualized arterial bolus real-time triggering. Bolus TTP-aorta was calculated and arterial-phase acquisitions were compared for accuracy and reproducibility using specific vascular enhancement indicators.Results: The mean bolus transit-time to peak-lesion contrast was 8.1 6 2.7 seconds following arterial detection, compared to 32.1 6 5.4 seconds from contrast injection, representing a 62.1% reduction in the time-variability among subjects (N ¼ 18). The real-time bolus-triggered technique more consistently captured the targeted arterial phase (94%), compared to the fixed timing technique (73%), representing an expected improvement of timing accuracy in 28% of patients (P ¼ 0.0001389). Conclusion:Our results show detailed timing window analysis required for optimized arterial real-time bolustriggering acquisition of transient arterial phase features of liver lesions, with optimized arterial triggering expected to improve reproducibility in a significant number of patients.

We have applied image analysis methods in the assessment of human kidney perfusion based on 3D dynamic contrast-enhanced (DCE) MRI data. This approach consists of 3D non-rigid image registration of the kidneys and fuzzy C-mean classification of kidney tissues. The proposed registration method reduced motion artifacts in the dynamic images and improved the analysis of kidney compartments (cortex, medulla, and cavities). The dynamic intensity curves show the successive transition of the contrast agent through kidney compartments. The proposed method for motion correction and kidney compartment classification may be used to improve the validity and usefulness of further model-based pharmacokinetic analysis of kidney function.

End-stage-renal disease (ESRD) is a major health issue in the United States, and the Medicare costs of ESRD totaled nearly $21 billion in 2005. Renal transplantation has emerged as the treatment of choice in this patient population, providing improved quality of life and lower healthcare costs compared with other treatment options. Imaging evaluation of a graft kidney plays a critical role in the postoperative care of the renal transplant patient. In the past, diagnostic evaluation of the transplant kidney has depended upon a combination of ultrasonography, computed tomography, MRI, and biopsy, used in conjunction with the patient's clinical presentation. However, new and developing advances in MR technology has lead to the development of MR Nephro-Urography (MRNU), which provides both anatomic and functional evaluation of the kidney in a single examination. It is expected that the increasing use of MRNU will have a significant impact on the management of renal transplant patients. This review describes MRNU methodology, examines known posttransplant complications, and highlights the utility of MRNU as a comprehensive imaging examination to diagnose both surgical and medical complications of the transplant kidney.

http://radiology.rsnajnls.org/cgi/content/full/246/1/241/DC1.

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