[No detectable nephrotoxic side effect using a dimer, non-ionic contrast media in cerebral perfusion computed tomography in case of suspected brain ischemia]

Recent Advances in Gadolinium Based Contrast Agents for Bioimaging Applications

Gadolinium (Gd) based contrast agents (CAs) (Gd-CAs) represent one of the most advanced developments in the application of Gd for magnetic resonance imaging (MRI). Current challenges with existing CAs generated an urgent requirement to develop multimodal CAs with good biocompatibility, low toxicity, and prolonged circulation time. This review discussed the Gd-CAs used in bioimaging applications, addressing their advantages and limitations. Future research is required to establish the safety, efficacy and theragnostic capabilities of Gd-CAs. Nevertheless, these Gd-CAs offer extraordinary potential as imaging CAs and promise to benefit bioimaging applications significantly.

Applications of nanoparticles in biomedical imaging

An urgent need for early detection and diagnosis of diseases continuously pushes the advancements of imaging modalities and contrast agents. Current challenges remain for fast and detailed imaging of tissue microstructures and lesion characterization that could be achieved via development of nontoxic contrast agents with longer circulation time. Nanoparticle technology offers this possibility. Here, we review nanoparticle-based contrast agents employed in most common biomedical imaging modalities, including fluorescence imaging, MRI, CT, US, PET and SPECT, addressing their structure related features, advantages and limitations. Furthermore, their applications in each imaging modality are also reviewed using commonly studied examples. Future research will investigate multifunctional nanoplatforms to address safety, efficacy and theranostic capabilities. Nanoparticles as imaging contrast agents have promise to greatly benefit clinical practice.

No increased risk for contrast-induced nephropathy after multiple CT perfusion studies of the brain with a nonionic, dimeric, iso-osmolal contrast medium

BACKGROUND AND PURPOSE

Contrast-induced nephropathy (CIN) is one of the most common causes of in-hospital acute renal failure. The aim of this study was to assess the risk for CIN after repeated administration of the nonionic, dimeric, iso-osmolal contrast agent iodixanol regardless of pre-existing renal function. Changes in serum creatinine (SCr) levels were compared with those of control subjects who did not receive iodinated contrast media (CM).

MATERIALS AND METHODS

Between January 2005 and March 2007, a total of 100 consecutive patients were prospectively included. Patients underwent a CT perfusion (CTP) study of the brain from clinical signs of acute cerebral infarction. CTP was performed with an intravenous bolus of 60 mL of iodixanol-270. Precontrast and postcontrast SCr levels were obtained, and the CTP study was repeated within 32 hours and postcontrast SCR was assessed. The control group consisted of 100 patients scheduled for plain cranial CT examination, who were not exposed to iodinated CM.

RESULTS

Mean baseline SCr level was 0.96 +/- 0.35 mg/dL in the contrast group and 1.14 +/- 0.74 mg/dL in the control group. After repeated administration of CM, a total of 7 patients had a relative increase of greater than or equal to 25% compared with baseline. In the control group, a relative increase of 25% or more was seen in 12 patients. The difference in the incidence of the rise in SCr of >25% was not significantly different (P = .094).

CONCLUSION

Multiple contrast-enhanced studies with intravenously administered iodixanol are not associated with a higher risk for CIN compared with a control group receiving no CM.

Evaluation of the nephrotoxicity of iodixanol in patients with predisposing factors to contrast medium induced nephropathy referred for contrast enhanced computed tomography

To determine the risk of developing contrast induced nephropathy (CIN) in intermediate-risk patients receiving iodixanol, an iso-osmolar, dimeric non-ionic contrast agent, for CT in a clinical setting. Hundred consecutive patients referred for a contrast enhanced CT with a serum creatinine concentration>1.1mg/dl and/or a glomerular filtration rate (GFR)<90ml/min were included. Exclusion criteria were a serum creatinine>2.0mg/dl and a GFR<30ml/min or concurrent nephrotoxic agents. Between 60 and 140ml (mean 97+/-42ml) iodixanol (320mgI/ml) were administered at a flow of 2.5-3ml/s. Hydration with 500ml NaCl i.v. was performed before and after contrast injection. Follow-up was completed in 99 patients (age, 64+/-13 years, 68 men). CIN was defined as increase in serum creatinine concentration +0.5mg/dl or >25% above baseline within 72h after contrast administration. Serum creatinine concentration and GFR were 1.40+/-0.22, 1.29+/-0.29, and 1.26+/-0.29mg/dl and 52.2+/-13.9, 51.3+/-21.1, and 51.5+/-15.1ml/min on days 0, 3, and 7, respectively. Three out of 99 (3%) patients who received 90-110ml iodixanol revealed a CIN on day 3 without persistence on day 7. No specific therapy was needed. One out of 99 patients reported an exanthema on days 3 and 7. With the use of iodixanol in intermediate-risk patients, 3% of the patients develop CIN on day 3 without need for a specific therapy or persistence on day 7.

Iodixanol

OBJECTIVE

To assess the risk of contrast-induced nephropathy in cancer patients with underlying renal insufficiency receiving the iso-osmolar intravenous contrast agent iodixanol for diagnostic computed tomography (CT) examinations.

METHODS

Institutional review board approval was obtained with waiver of informed consent. Our study was a retrospective evaluation comparing the incidence of contrast-induced nephropathy in consecutive patients with underlying renal insufficiency undergoing diagnostic CT examinations receiving iodixanol from November 2003 to June 2005 with a comparison group of patients with normal baseline renal function over the same period. Renal insufficiency was considered a serum creatinine level more than 1.2 mg/dL in females and more than 1.5 mg/dL in males. Contrast nephropathy was considered an absolute elevation of 0.5 mg/dL or 25% elevation in serum creatinine level.

RESULTS

In the group of patients receiving iodixanol with underlying renal insufficiency (189 patients), 9.0% developed contrast nephropathy (P = 0.015) with 4.8% of patients developing irreversible renal damage (P = 0.03). This compared with 4.9% of patients receiving iodixanol (185 patients) and 3.1% of patients receiving iohexol (194 patients) with normal baseline renal function developing contrast nephropathy (P = 0.38) with 3.2% of the iodixanol patients and 1.0% of the iohexol patients developing irreversible renal damage (P = 0.13).

CONCLUSIONS

The risk of contrast-induced nephropathy is significantly higher in patients with underlying renal insufficiency receiving iodixanol than that for patients with normal baseline renal function, but this should not serve as an absolute contraindication for these patients to receive intravenous iodinated contrast for diagnostic CT examinations particularly in patients with life-threatening clinical questions in which contrasted CT may provide valuable information.