Contrast Medium Administration in the Elderly Patient: Is Advancing Age an Independent Risk Factor for Contrast Nephropathy after Angiographic Procedures?

Contrast medium-induced nephropathy (CMIN) is the third leading cause of hospital-acquired acute renal dysfunction. Even if the number of patients over 75 years of age undergoing diagnostic and/or interventional procedures and requiring administration of contrast medium (CM) is growing constantly, at present there is no definitive consensus regarding the role of advancing age and related morphologic or functional renal changes as an independent risk factor for CMIN. The authors review the evidence from recent medical literature on the definition, pathophysiology, and clinical presentation of CMIN as well as therapeutic approaches to its prophylaxis. Attention is focused on advancing age as a preexisting physiologic condition that is, per se, able to predispose the patient to CM-induced renal impairment, assuming that every elderly patient is potentially at risk for CMIN.     

Iodine removal in intravenous dual-energy CT-cholangiography: Is virtual non-enhanced imaging effective to replace true non-enhanced imaging?

Purpose

To evaluate whether virtual non-enhanced imaging (VNI) is effective to replace true non-enhanced imaging (TNI) applying iodine removal in intravenous dual-energy CT-cholangiography.

Materials and Methods

From April 2009 until February 2010, fifteen potential donors for living-related liver transplantation (mean age 37.6 ± 10.8 years) were included. Potential donors underwent a two-phase CT-examination of the liver. The first phase consisted of a single-energy non-enhanced CT-acquisition that provided TNI. After administration of hepatobiliary contrast agent, the second phase was performed as a dual-energy cholangiographic CT-acquisition. This provided VNI. Objective image quality (attenuation values [bile ducts and liver parenchyma] and contrast-to-noise ratio) and subjective overall image quality (1 – excellent; 5 – non diagnostic) were evaluated. Effective radiation dose was compared.

Results

For TNI and VNI, attenuation values for bile ducts were 16.8 ± 11.2 HU and 5.5 ± 17.0 HU (p < 0.05) and for liver parenchyma 55.3 ± 8.4 HU and 58.1 ± 10.6 HU (n.s.). For TNI and VNI, contrast-to-noise ratio was 2.6 ± 0.6 HU and 6.9 ± 2.1 HU (p < 0.001). For VNI, subjective overall image quality was 1 in ten datasets, 2 in four datasets and 3 in one dataset. Effective radiation dose for the dual-energy cholangiographic CT-acquisition was 3.6 ± 0.9mSv and for two-phase single-energy CT-cholangiography 5.1 ± 1.3mSv (p < 0.001).

Conclusion

In this study on iodine removal in intravenous dual-energy CT-cholangiography, subjective image quality is equivalent, contrast-to-noise ratio is improved and effective radiation dose is reduced when VNI is performed. The differences between TNI and VNI with respect to attenuation values seem to have limited clinical relevance and therefore we consider VNI as effective to replace TNI.     

Is There a Way to Predict Outcome in (Near) Term Neonates with Hypoxic-Ischemic Encephalopathy Based on MR Imaging?

BACKGROUND AND PURPOSE: It has previously been demonstrated that comparison of signal intensity (SI) between selected brain structures on T1-weighted images enables distinction between the absence or presence of hypoxic-ischemic (HI) brain injury in young infants. The aim of the present study was to assess whether this method of brain structure T1-weighted SI comparison also enables prediction of outcome.MATERIALS AND METHODS: Survivors of a group of 57 children with neonatal HI encephalopathy (HIE) grade 2 or 3 according to Sarnat and Sarnat and controls who underwent neonatal MR imaging were retrospectively assigned to 1 of 3 outcome groups at 5 years of age, depending on developmental outcome: 1) normal, 2) mildly abnormal, and 3) definitely abnormal. Gestational age was not significantly different between the HIE group (range, 35 + 5–42 + 5 weeks; mean, 39 + 4 weeks) and control group (range, 35 + 0–42 + 1 weeks; mean, 39 + 2 weeks). We calculated the predictive values of the neonatal clinical HIE classification according to Sarnat and Sarnat for outcome (neonatal death and developmental outcome in survivors). We assessed which brain structure T1-weighted SI comparison scored best for outcome prediction. Predictive values of that comparison for outcome were calculated for the entire group and for the HIE grade 2 group only, a patient group with highly variable outcome.RESULTS: Of the 57 children, 6 died. Outcome group 1 consisted of 31; group 2, of 14; and group 3, of 6 children. The positive predictive value of the neonatal clinical classification for adverse outcome (outcome group 3 and death) was 52%; and negative predictive value, 100%. These were respectively 45% and 0% in children with HIE grade 2. Of all brain structure T1-weighted SI comparisons, that of the posterior limb of the internal capsule versus the posterolateral putamen scored best for outcome prediction. The positive predictive value for adverse outcome was 69%; and negative predictive value, 98%. In children with HIE grade 2, the positive predictive value and negative predictive value for adverse outcome were 67% and 88%.CONCLUSIONS: Brain structure T1-weighted SI comparisons are helpful to predict outcome in (near) term neonates with HIE. This finding adds to the current knowledge and clinical practice. If the SI in the posterolateral putamen is less than the SI in the posterior limb of the internal capsule, favorable outcome is very likely, whereas if the SI in the posterolateral putamen is equal to or greater than the SI in the posterior limb of the internal capsule, adverse outcome is very likely. In neonates with HIE grade 2 according to Sarnat and Sarnat, prediction of outcome is substantially improved by using these brain structure T1-weighted SI comparisons.

For neonates with hypoxic-ischemic brain (HI) injury, the predictive value of neonatal MR imaging for neurologic development until school age has been reported.^1-4 Abnormal or absent myelination of the posterior limb of the internal capsule is associated with impaired motor outcome.^1,3,5 Abnormal signal intensity (SI) in the basal ganglia and/or the thalami is associated with impaired cognitive and motor outcome.^1-5 We aimed to assess the predictive values for early neonatal death or developmental outcome at school age of a simple method by using MR imaging without looking at patterns of brain injury.In a recent article by our group⁶ involving 57 young infants born after a gestational age of >35 weeks, we demonstrated that 2 brain structure SI comparisons (the posterior limb of the internal capsule versus the posterolateral putamen, and the corona radiata versus the peri-Rolandic cortex) on T1-weighted images permitted the prediction of the absence or presence of HI brain injury and enabled distinction in 37/57 infants between hypoxic-ischemic encephalopathy (HIE) (neonatal HIE grade 2 or 3 according to Sarnat and Sarnat⁷) and no HIE. With this method, for each subject, SI scores were assigned to 19 different complete brain structures, on the basis of pair-wise comparisons of SI among the 19 structures. The advantage of this method is that it is easy to implement, by using standard T1-weighted images without a need for advanced MR imaging techniques. The study did not relate MR imaging findings to outcome.The aim of the present study was to assess whether this method of brain structure T1-weighted SI comparison enables prediction of neonatal death or normal, mildly abnormal, or definitely abnormal developmental outcome at 5 years of age.