Imaging Protocols and Techniques

Survey about MR Spectroscopy from the TRANSACT project

TRANSACT is an EU-funded FP7-PEOPLE Marie Curie Initial Training Network (ITN) running from March 1, 2013 till February 28, 2017. The aim is to Transform Magnetic Resonance Spectroscopy into a Clinical Tool (http://www.transact-itn.eu/).

One of the objectives of the project is to join existing decision-support (INTERPRET http://gabrmn.uab.es/dss) and classifier (SpectraClassifier http://gabrmn.uab.es/sc) systems to jMRUI (http://www.mrui.uab.es/mrui/), as plug-ins that facilitate the use of MRS in the clinic.

It is for this reason that we are conducting a survey among users of jMRUI or, in general, any user of MR Spectroscopy, that has ever had the need to process this type of data. We are interested in knowing which type of user you are, which are the scanners you have available and the software or tools that you use to analyse your MR spectroscopy data.

Although most of the questions are mandatory, many are so trivial that you will answer them in a blink of an eye, and  it should take you no more than 15 minutes to complete the survey.

To go to the survey, click the following link:

https://docs.google.com/forms/d/1CVKohz8A73tGN-pksjkCExBnEfAsM16TQ6j33OypWww/viewform

Thanks for your collaboration!

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Open letter in response to NYT article from July 31, 2010 “The Radiation Boom After Stroke Scans, Patients Face Serious Health Risks” By WALT BOGDANICH

posted by Michael H. Lev and Max Wintermark

Every year in the United States, more than three quarters of a million people have a stroke, and approximately every 3 minutes someone dies from a stroke. A significant portion of stroke victims are young, and left with a devastating handicap for the rest of their lives. The monetary and societal costs of stroke represent a major economic challenge to the healthcare system.  With stroke – as with heart attack – rapid treatment is essential to limit the extent of irreversible brain injury (“time-is-brain”), and rapid determination of the cause and degree of existing brain injury can be critical in deciding treatment.

CT perfusion imaging is a quick, widely available test that displays information about blood flow to the brain that can help diagnose, treat, and predict outcome in stroke patients.  When MRI is not readily available or contraindicated, CT perfusion imaging provides the best possible estimate of brain tissue likely to die without urgent, advanced therapies, including arterial “clot busting” drugs and blood clot retrieval devices.  CT perfusion imaging can also help classify reversible brain injury (“transient ischemic attacks”) that – like cardiac angina – may not require such immediate, aggressive treatment, as well as evaluate brain injury caused by arterial spasm due to bleeding from aneurysm rupture.

Published protocols for performing CT perfusion imaging at “as low a radiation dose as reasonably achievable” – a principle endorsed by the American College of Radiology and American Society of Neuroradiology – have circulated in the medical community for over a decade.  Strict protocol rules and oversight radiation protection personnel at most medical centers ensure that optimal image quality is maintained with a total radiation exposure often considerably lower than the current FDA recommended maximum dose.  Indeed, in an early, highly quoted study …

CT Head – What Slice Thickness Do You Use?

Until recently we have been scanning routine CT heads using a sequential technique with 5 mm slices through the posterior fossa and 10 mm slices of the supratentorial compartment. With a change of machines the protocols were revamped and we are now using sequential 5 mm thick slices all the way through.

One of my colleagues has complained about this change, stating that lesion conspicuity will be reduced by using thinner slices above the tent. I personally prefer the uniform and thinner slice thickness but cannot find anything in the literature to support either argument – there is lots about acquiring as thinly as possible in the posterior fossa but nothing regarding the optimum slice thickness for the cerebral hemispheres.

Can anybody help?…

Radiation Dose in Neuroradiology: New Special Collection and Podcast

By now most Neuroradiologists are aware of the US Food and Drug Administration notification regarding dangerous levels of radiation exposure produced in one facility while performing CT perfusion. This unfortunate event has been front page material for the media, leading to patient anxiety and, more important, to questions regarding the use of this valuable technique. The facility involved has recently revealed that  260 patients were exposed to high radiation levels; 20% of cases involving the eyes which places these individuals at high risk for cataracts. It should come as no surprise that by the time of this writing, legal action against that facility and the equipment manufacturer have been initiated. Shortly thereafter, in a different facility, a technologist scanned the same region of a child’s head 151 times! Because radiation exposure from diagnostic tests has received considerable notice—even before these 2 incidents—it behooves all of us to employ our equipment judiciously.  In many instances, the benefits far outweigh the risks of radiation exposure.

In a timely fashion that only electronic publication allows, Drs. Max Wintermark and Mike Lev, experts on CT perfusion, have put together a wonderful editorial (to appear in the print edition of AJNR, too) and an informative Special Collection on radiation exposure-related articles. Our series of Special Collections is biannual but when we believe that our readers and society constituency need further information, we can rapidly act and deploy educational materials that will keep us all well versed and up-to-date.

Additionally at www.ajnr.org you will be able to find our first podcast.  Our podcast editor is Dr. Doug Phillips from Cornell University.  This podcast is a group discussion regarding radiation exposure and CT scanning.  The group participants are Drs. Wintermark, Lev, Schaefer and Sanelli all experts in this field.  Before this podcast was recorded I invited …

The Microcirculation in the “Target Node“ as Outcome Prognosticator: Facts and Implications

In the recent paper of Kim et al. [1], the authors attempt for first time to examine the relationship between pharmacokinetic parameters, obtained by dynamic contrast-enhanced (DCE)-MRI, of a metastatic target node and treatment outcome in patients with neck cancer. The paper makes 3 important contributions to the DCE neck imaging: 1) adding to the evidence gained by Cao et al. [2], Kim et al. derived (based on a two-compartment pharmacokinetic model) quantitative perfusion-associated parameters 2) similarly to the work of Bisdas et al. [3] microcirculation parameters (other to blood flow, blood volume, and permeability) such as Ktrans (transfer constant), ve (extravascular extracellular space volume fraction) and τi (intracellular water lifetime) are introduced in the characterization of neck cancer; 3) for first time Kim et al. examine exclusively the pre-treatment microcirculation parameters of nodal disease in neck cancer, trying to evaluate their predictive value. But let’s take a closer look to these 3 important aspects of the paper.

The quantification of the perfusion parameters in neck cancer is valuable as the quantitative results may facilitate an objective disease monitoring in the same institution and, under certain circumstances, an interchangeability across different institutions. Nowadays, theoretical models deliver quantitative information (of course under certain inevitable assumptions concerning the relationship between MR signal and contrast agent concentration) which are obviously superior to heuristic (semi-quantitative) DCE parameters, such as peak enhancement, maximum upslope, time-to-peak enhancement, and washout slope. In the future, DCE-MRI should be besides CT a major player in this field and combined with diffusion-weighted sequences and spectroscopy may face equally the PET/CT.

Kim et al. focused on the nodal disease, which is a rather unattended aspect in the DCE imaging of neck cancer. The authors found significantly elevated baseline Ktrans in responders, which presumably has led to a better distribution of the …

Brachial Plexus MRI Protocol

BP MRI Protocol

Fall is upon us and so is the lecturing season! Like years before, this Fall I will be giving my brachial plexus lecture several times and the most commonly asked question by the audience is: “where can I get your MRI protocol?” For this reason I am posting it here.  Posting of protocols seems to gather considerable attention; Dr. Wiggins post on MRI and CT protocols has been viewed over 1900 times!  Caveats regarding this post: our BP protocol was designed to satisfy the needs of our clinicians here at UNC, your referring physicians may be expecting different information and you will have to adjust it to meet their needs.  There is more “than one way to skin a cat”: I suggest looking at the way others image the BP.  Dr. Ken Maravilla and his group at the University of Washington use MR neurography, a technique that we do not have but produces lovely images of the peripheral nerves.  They have published extensively about it.  Brian Bowen from the University of Miami has also written several articles on imaging of the BP and uses a very nice protocol which is different than ours.…