PalMD is a practicing internist in the Great Lakes region of the U.S.. Aside from the great joy he finds in his family and his work, he likes communicating some of that joy to others. He has a special interest in the ways patients---and we are all patients at one time or another---are deceived by charlatans. He aims to change the world, one reader at a time. Previous writings can still be found 
A news item this week profiles a northeast naturopath who is using thermal imaging to screen for breast cancers. This is a frightening development. The news about conflicting mammogram recommendations has women wondering what the right approach really is. The question in the new USPSTF recommendations is one of values. The science says that a lot of women in their 40s need to be screened and undergo invasive procedures to save one life. We are left to decide if that life is worth it. Or we can throw our hands in the air and start charging women for useless alternatives.
The technology being sold by the naturopath is digital infrared thermographic imaging (DITI). The idea is that by looking at the heat pattern of the breasts, we might be able to detect the increased blood flow and heat of cancers. It is not an implausible claim, and it may be worth investigation. The one legitimate clinical study published so far had some promising results, but that's not how we develop screening procedures. There is a well-understood statistical method for evaluating diagnostic tests. In evaluating a new test, it is tested against a "gold standard" in a representative population. Various factors need to be taken into account, including the comparative costs, risks, benefits, prevalence of disease, etc. It is not just a matter of saying, "this could work! Let's do it!".
Launching a new screening technique before the data support it is dangerous. It may expose patients to unknown risks, and if its negative and positive predictive value are either unknown or not good, it will lead to a false sense of security as disease is missed, and lead to unnecessary procedures as benign findings are pursued.
Doctors and other "healers" who offer this sort of thing are behaving recklessly and unethically. If a practitioner does not understand the science well enough to know this, they shouldn't be allowed to practice. If the do understand but offer it anyway, they should be punished.
Medicine & Health
Comments
Actually, the reason thermography went the way of the dodo, medically speaking, is because newer modalities, such as MRI, provide all the same information (where the blood flow is) and at the same time produce beautifully detailed 3D reconstructions. Also, earlier technology had very poor resolution. It's possible that newer thermography machines may do better, but it's a multidecade task to validate a new screening test. As you say, it has to be tested on a large population head to head with existing technology, and its use has to be shown to decrease mortality from the disease being screened for.
Posted by: Orac | November 27, 2009 12:27 PM
A local pharmacy here sells a glorified flashlight marketed to screen for breast cancer by shining it on yourself.
Along side a "flu kit" with antibacterial soap and coldfx. The woo is embarrassingly abundant some days.
I switched my prescriptions to a pharmacy/store that doesn't sell such products, after I saw that.
I'm starting to think there's no depths to which purveyors of these things won't sink.
Posted by: Nico | November 27, 2009 12:44 PM
It is hard to imaged increased resolution, with wavelengths which are so large. This is a physical limitation. Any solution would involve some complex modeling built into to the system, which would give a probability which is equal to the direct observation from higher resolution techniques.
Posted by: Matthew Putman | November 27, 2009 3:22 PM
The longest IR wavelengths are shorter than the hydrogen resonant frequencies used in MRI (formerly NMR) at reasonable field strengths.
The problem with IR imaging isn't resolution, it's opacity. It doesn't penetrate well enough to provide a reasonable SNR.
Assuming that breast tumors really have useful degrees of vascular differentiation from normal tissue, I would expect that vascular contrast enhancers (Iodine? Sounds familiar from kidney radiology a while back) would be more to the point. But that's just an engineer talking who can't pass up speculating about a problem when he hears one, even if he doesn't have the first clue about the field.
Take anything I say seriously and you're more of a damn fool than I am.
Posted by: D. C. Sessions | November 27, 2009 5:19 PM
They do, which is why they use gadolinium-based contrast agents for MRI. They produce beautiful images of tumor vascularity compared to the surrounding normal tissue.
Posted by: Orac | November 27, 2009 5:38 PM
Thanks, Orac -- it's nice to know that sometimes totally random shots in the dark score.
Posted by: D. C. Sessions | November 27, 2009 7:10 PM
the science also says a lot of women in their 50s need to be screen and have over treatment and have invasive procedures to save one life. The science also gives some insights (but not enough) into who will be saved, the task force did not really give much insight into that. obviously this is where we need to put money in the basket (which also mean "experimental" random screens of women in 40s and 50s.
and (to beat dead horses), the failure of the task force to write the paper understanding it was not a mundane exercise (read the NY times piece last week, the stupid task force folks actually stated something to that effect) gives a lot of room for the woo meisters to walk all over this.
Posted by: rb | November 27, 2009 7:53 PM
Forgive my ignorance, but exactly what is their rationale and reasoning that thermal imaging of breast tissue will identify tumors?
Posted by: TennesseeParamedic | November 28, 2009 12:40 AM
Arterial blood is warmer than relatively fatty, low-metabolism superficial tissue. Tumors have enhanced blood flow and higher metabolic needs. Thus tumors are warmer than surrounding tissues. Warmer tissues radiate more in the infrared, thus an infrared thermal image should show tumors.
It might even work if said tumors were on the surface, but it apparently isn't even a reliable technique for melanoma -- which is a lot more aggressive than (most?) breast cancers.
Posted by: D. C. Sessions | November 28, 2009 5:19 AM
First and foremost, thermography does no harm, which can not be said for mammography and it's harmful radiation. There are 800 clinical studies supporting thermography which are readily available from the internet. The most basic rule of thermography is that it does not diagnose cancer (a cancerous tumor actually shows up cold), but reveals the buildup of nurishing blood vessels (angiogenesis) a cancer needs to survive. Thermography is for early detection so that preventative measures can be taken to stop the development of a tumor. Mammography is late stage detection resulting in surgery, more radiation and chemotherapy.
Posted by: David Rosenthal | November 29, 2009 12:03 AM
@ D.C. Sessions and Orac- Due to its high molecular weight, iodine is an opacifying agent for radiography. Gadolinium is a "shift reagent" used in NMR to spread-out the signals.
@ Mr. Rosenthal, "There are 800 clinical studies" is a data dump- if you cannot cite the relevant, high-quality studies then we must assume that you don't know them. "Thermography is for early detection" is unproven. "[P]reventative measures can be taken to stop the development of a tumor." Pray tell, what are those measures? Overall, it sounds like you are promoting a bogus "diagnosis" followed by bogus "treatment." The only certain result is a lightening of your customers' wallets.
Posted by: Joe | November 29, 2009 5:46 AM
I'm with Joe on this one. Studies need to be cited individually. More importantly, the failure of the task force to write the paper understanding it was not a mundane exercise.. it was a necessity.
Posted by: Freelance MD | November 29, 2009 9:07 PM
Oh yeah? Well there are NINE hundred clinical studies, which are readily available from the internet, supporting that your mama is fat.
Burned!
Posted by: James Sweet | November 30, 2009 2:15 PM
...provided it costs no money, takes no time, and supplants no other measures, while providing no false sense of security to anybody.
Hippocrates offered an impossible challenge; everything does some harm, even refraining from doing anything. the real trick is to minimize the harm struck by your trade-offs. thermography, too, certainly does harm --- the question is how much.
Posted by: Nomen Nescio | December 4, 2009 11:17 PM