ACR guidence document for safe mr practices:2007

The ACR is Revising their “whitepaper” on safety and it should be out later this week. Here is a small summary of the Contrast safety issues. This was recently summerized by Dr. Emanuel Kanal. Here is the Email as follows:

OK – I’ll try to summarize off the cuff as best as I can some of the salient points that will be covered in the upcoming document:

1. The ACR does NOT recommend prospectively checking serum creatinines or GFRs on all potential MR patients. Instead it is recommended that we verbally query each potential patient (as we do now regarding pacemakers, metallic implants, etc.) if they have a history of “Kidney disease or are on dialysis”. If not, no special handling is recommended at this time. If the answer is in the affirmative, then each such case is forwarded to a radiologist for further evaluation and decision making (is contrast indicated for their MR study, if so, how much, which agent, for what sequence(s), etc.) We continue to recommend that if any renal disease patient (stage 3 or worse) is to get any GBMCA it is prudent to consider administering the lowest dose absolutely required for diagnosis, and with no other specific value, consider no more than half dose. And NO Omniscan for any patient with any level of renal disease.
2. The FDA feels that for any and all patients with moderate (59<gfr3. The European Medicines Agency (EMEA) do not recommend hemodialysis following the administration of the GBMCA, even on patients already on hemodialysis. They also feel that Omniscan (and Optimark, although the latter is not licensed in Europe) should be outright contraindicated for patients with severe (or end stage, of course) renal disease, and that one should be quite cautious before administering any of the other agents to patients with severe or end stage renal disease. To my knowledge, the only other agent (of the 7 available in Europe and 5 available in the US) for which there do seem to be reports of NSF developing after the isolated administration of (only) that agent (besides for Omniscan and Optimark) is Magnevist – but this is not addressed in the European statement other than to state that they would include a statement in the product labelling to state that NSF has been associated with the administration of that drug for those drugs for which that statement applies.
4. The ACR does not concur with EITHER of the above two points of view. Firstly, we do not condone seriously considering hemodialysis on patients with moderate, and possibly not even severe, renal disease who get a low dose of a non-Omniscan, non-Optimark GBMCA. The risks of initiating hemodialysis (HD) on a patient not already on HD are non-trivial and probably far outweigh the risks of developing NSF after half dose of Multihance or Prohance or even Magnevist (despite the fact that there appear to have been a few cases of NSF having developed after isolated Magnevist administration, although, in my opinion, at a rate that appears to be far BELOW that associated with market share). However, for patients already ON hemodialysis, we strongly recommend that the patient be sent for HD IMMEDIATELY following the completion of the MR study for which the GBMCA had been administered. Much of the opinion of the European community in not recommending HD following GBMCA administration seems to be based on not having any data that suggests that it is helpful in preventing the ultimate development of NSF. However, much of THIS seems to be based on the article by Broome, et al where they found that 3 of 12 NSF patients developed NSF even though they had undergone HD the day of their MR study, as he published in his article. However, I have spoken with Dr. Broome personally, and asked him to go back and check how LONG after the DOUBLE DOSE Omniscan each of these had received did they wait before initiating HD, which he kindly agreed to do. For one of the three patients that information is not available. For another it was *** 9 hours *** later, and for the third it was *** 18 hours *** after the Omniscan was administered. Since pharmacokinetics dictates that the first few minutes and hours are by far the most critical in concentration gradients and movement of these molecules/ions, and since transmetallation and release of free gadolinium seems to play a likely role in the ultimate development of NSF, it seems exceedingly reasonable to try to dialyze the GBMCA out of the HD patient as soon as we no longer need it in there for diagnostic purposes. Thus, the ACR Committee on Contrast Agents and Drugs as well as the ACR MR Safety Committees both concur that all HD patients who receive a GBMCA should proceed IMMEDIATELY to the dialysis center for HD as soon as the MR study (for which the GBMCA had been administered) is complete.
On the other hand, the FDA does not seem to treat (at this time, at least) Omniscan (or Optimark) in any way uniquely among the other GBMCA – which I simply cannot understand. Here the ACR agrees with the Europeans that one should consider the administration of Omniscan (or Optimark, is how the Europeans put it, with the word “Optimark” in parentheses, since Optimark is not licensed in Europe) outright contraindicated in patients with severe renal disease.
So you see, the present state of the art is that although there is a LOT of agreement between the ACR, the FDA,and the EMEA (European Medicines Agency), in the areas in which there is disagreement you will find that the ACR’s recommendations are between the two “extremes” of that of the FDA and EMEA.
I checked with the AJR/ARRS office a few moments ago, and was again reassured that we will likely still make our end-of-February self imposed deadline for completion and posting of the “ACR Guidance Document for Safe MR Practices: 2007” and its contained NSF overview and recommendations. Stay tuned, and I hope this helps!

Best wishes and be well – always –
manny – Monday, February 26, 2007; 2:55 PM
Emanuel Kanal, MD, FACR, FISMRMDirector, Magnetic Resonance ServicesProfessor of Radiology and NeuroradiologyDepartment of RadiologyUniversity of Pittsburgh Medical Center

Double Aortic Arch

Double Aortic ARCH

Background: Double aortic arch is one of the two most common forms of vascular ring, a class of congenital anomalies of the aortic arch system, in which the trachea and esophagus are completely encircled by connected segments of the aortic arch and its branches. Although various forms of double aortic arch exist, the common defining feature is that both the left and right aortic arches are present.
The simplest way to understand the anatomy and development of double aortic arch and other forms of vascular ring is to begin by considering the bilateral system of pharyngeal arch vessels in the early embryo.
Early in the course of embryonic morphogenesis, 6 pairs of pharyngeal arch arteries develop in conjunction with the branchial pouches. The first through sixth arches appear in a more or less sequential fashion, with left-to-right symmetry, and constitute the primitive vascular supply to the brachiocephalic structures, running from the aortic sac to the paired dorsal aortas. As normal cardiovascular morphogenesis proceeds, a patterned regression and persistence of the various arches and right-sided dorsal aorta occur, ultimately resulting in the mature configuration of the thoracic aorta and its branches. The third, fourth, and sixth arches, along with the seventh intersegmental arteries and the left dorsal aorta, are the primary contributors to the normal aortic arch and its major thoracic branches (see Image 1).
The segments of the bilateral aortic arch system that normally regress include the distal portion of the sixth arch and the right-sided dorsal aorta. Normally, the left fourth arch becomes the aortic arch, the right fourth arch contributes to the innominate artery, the distal left sixth arch becomes the ductus arteriosus, the proximal sixth arches bilaterally contribute to the proximal branch pulmonary arteries, the left dorsal aorta becomes the descending thoracic aorta, and the dorsal intersegmental arteries bilaterally become the subclavian arteries.
Vascular rings are formed when this process of regression and persistence does not occur normally, and the resulting vascular anatomy completely encircles the trachea and esophagus. (Other forms of aortic arch anomalies occur in which a vascular ring is not present.) A double aortic arch is formed when both fourth arches and both dorsal aortas remain present.
Various forms of double aortic arch exist. Both arches may be patent, or an atretic (but persistent) segment may exist at one of several locations in either arch. When both arches are patent, the right or left arch may be larger, or they may be similar in size. A cervical arch on either side, variable laterality of the descending thoracic aorta, coarctation of the major arch, and/or discontinuity of the central pulmonary arteries may be present. In general, the apex of the right-sided arch is more superior than the left arch, and on occasion, a cervical arch may be present on either side.
In more than 75% of patients with double aortic arch, the right arch is dominant. Among patients with a right-dominant double arch, those with a patent minor arch outnumber those with an atretic minor arch. When the minor arch is atretic, the atretic segment almost always is distal to the left subclavian artery, although atresia also may occur between the left common carotid and subclavian arteries. In approximately 20% of patients, the left arch is dominant. In these patients, the minor right arch typically is patent.

Associated cardiovascular anomalies
Double aortic arch usually occurs without associated cardiovascular anomalies. Ventricular septal defect and tetralogy of Fallot probably are the most common associated defects, although truncus arteriosus, transposition of the great arteries, pulmonary atresia, and complex univentricular defects sometimes occur in conjunction with a double arch.

What signs and symptoms does it cause?
seal-bark cough
nearly constant non-positional stridor, in inspiration more than expiration (usually noted at 2-6 weeks old)
respiratory distress
recurrent respiratory infections and pneumonia
cyanotic episodes
widened superior mediastinum on chest radiograph
vomiting and feeding intolerance (infants)
dysphagia or choking (in children old enough to eat solid food)

Links Related to Double Aortic Arch
Anatomy of the AortaClinical Anatomy of the Aorta (PDF file) College of Osteopathic Medicine, University of Ohio
Links to Articles About Various Types of Vascular RingsVascular Rings The Child’s Doctor- Journal of Children’s Memorial Hospital (Chicago) – Spring 1998Vascular Ring, Double Aortic Arch eMedicine (Pediatric Cardiology) – July 17, 2002Vascular Ring eMedicine (Thoracic Surgery) – June 10, 2002Pulmonary Sling & Double Aortic Arch Learning
Patient/Family Education ResourcesDouble Aortic Arch Johns Hopkins Children’s Center (includes surgical information)Double Aortic Arch University of Virginia Children’s Heart Centre – March 18, 2003Double Aortic Arch Mayo Clinic – August 27, 2004
Case StudiesRecurrent Coins and Recurrent Respiratory Infections Radiology Cases in Pediatric Emergency Medicine (University of Hawaii)Difficulty Breathing Throughout Infancy Radiology Cases in Pediatric Emergency Medicine (University of Hawaii)Biphasic stridor in infancy Medical Journal of Australia – 2004Double Aortic Arch University Hospitals of Cleveland – Department of RadiologyBalanced type of double aortic arch Schweiz Med Wochenschr – 1999Adult with history of CABG University of Pittsburgh – March 2001