e-newsletter

Wet Reading

Diagnostic Imaging eNewsletter

January 2010 - Vol. 6, No. 3

 

 

Changes In Gadolinium Policies Reduce Incidence Of NSF

With nephrogenic systemic fibrosis (NSF) and its relationship to the intravenous gadolinium (Gd) based contrast agents (GBCAs) administrated during MR imaging having now been well studied for nearly five years, several important truths have become clear:

  • NSF has exclusively occurred in hospitalized patients with co-existing pro-inflammatory conditions.
  • The presence of a free Gd ion appears to be the trigger for the development of NSF.
  • Different GBCAs have different frequencies of association with NSF.
  • The ease with which the Gd ion in a GBCA is able to dissociate from its chelating ligand and the GBCA thermodynamic stability are probably the most important etiologic factors.
  • Gadodiamide (Omniscan™) has one of the highest dissociation rates and lowest thermodynamic stability of all of the GBCAs.
  • No documented cases of NSF have occurred with the use of gadobenate dimeglumine (MultiHance®), which has a very low Gd dissociation rate and high thermodynamic stability.

The GBCAs which are least associated with NSF are thermodynamically stable and have ligands which do not easily dissociate from the Gd ion.

Given the current knowledge about NSF, our GBCA policy has been recently modified. The following protocol has also been endorsed by the NCH Departments of Nephrology, Pathology and Laboratory Services:

  • As outpatients are considered at very low or no risk of NSF, we no longer require eGFR testing or screening questionnaires if there is no known kidney disease, and we will exclusively use MultiHance® in outpatients with renal disease.
  • We will continue to screen inpatients, but our new questionnaire will place fewer patients into the high risk category.
  • In some clinical situations the benefits of GBCA administration in high risk inpatients may outweigh the theoretical risks of NSF, and the radiologist and referring clinician may choose to proceed with GBCA administration.
  • Omniscan™ has never been utilized for MR imaging at NCH and will not be used in the future.

A recently published article (Radiology 2009: 253:689) found no cases of NSF at two institutions adopting similar policies.

 

      

New Mammography Guidelines Misguided

The US Preventative Services Task Force (USPSTF) published new breast cancer screening guidelines late last year (Ann Intern Med 2009;151:716) that have generated controversy - and at times furor - within both the medical and lay communities. The USPSTF now recommends against routine mammographic screening in women under age 50 years, reversing their own 2002 guidelines and with this new statement running contrary to the advice given by nearly every medical society involved with breast cancer, namely that women begin routine mammographic screening at age 40.

The explanation given by the USPSTF for their mammography policy change is that "there is moderate evidence that the net benefit is small for women aged 40-49 years." Specific reasons listed for no longer recommending mammographic screening in women under age 50 include "psychological harms, unnecessary imaging tests and biopsies in women without cancer, and inconvenience due to false-positive screening results." Yet the same article admits that "the benefit of screening seems equivalent for women aged 40-49 years and 50-59 years." The new recommendations are both confusing and potentially harmful to women.

Thankfully, major professional societies and organizations who deal more directly with breast cancer - specifically the National Cancer Institute (NCI), American Cancer Society (ACS), American College of Radiology (ACR), American College of Obstetricians and Gynecologists (ACOG) and American Medical Association (AMA) - have come out strongly against the new USPSTF recommendations, all advising women to continue to begin mammographic screening at age 40. Heath and Human Services (HHS) Secretary Kathleen Sebelius has also distanced herself and the Obama administration from the USPSTF, stating that "the recommendations will not impact government policy" and urging women to "keep doing what you've been doing."

The National Cancer Data Base (NCDB) benchmark report on breast cancer published in 2005 revealed that more than 5,000 of the nearly 32,000 (15.9%) diagnosed cases of breast cancer that they studied occurred in women aged 40-49 (chart above). At NCH in 2008, an even greater proportion (37%) of all diagnosed breast cancers were found in this age group.

While breast cancer is less prevalent in women in their 40s when compared to women in their 50s, this difference is small. Most importantly, the potential years of life lost to a lethal breast cancer in these women is by definition significantly higher. A recent NCH press release officially opposes the conclusions of the USPSTF.

Thanks to Dr. Ian Boiskin for the information on GBCA administration and NSF.

For more information about Northwest Radiology Associates, the services we provide, and how to contact individual radiologists, please visit our web site: northwestradiologyassociates.com.

If you wish to be added to our distribution list, or if you have any questions or comments, please email: ckalbhen@nch.org.