March 1997
Are We Out of the Gray Area Yet? Recent Developments in the Use of PET and SPECT Scans to Prove Causation and Injury in Toxic Tort Litigation
I. Introduction
One of the most valuable claims in personal injury litigation – or, from the perspective of a defense attorney or claims adjuster, the most expensive – is one involving a brain injury. Historically, the genuine brain injury claim was relatively rare and typically confined to a case involving a catastrophic accident or acute chemical exposure. In the severe case, the “proof” of the brain injury was readily obvious, and there was little debate that the resulting handicap or other physical manifestation was both real and serious.
Any less-than-serious brain injury claim, on the other hand, often was viewed with skepticism. At the heart of the plaintiff’s evidence was his or her complaints of some imperceptible injury or symptom (headache, memory loss, dizziness, confusion, to name a few) that could not be proven by any visual means. Even if an expert could explain by inference some hidden neurological injury that would account for the symptoms, it was still an injury that a jury could not see.
With advancements in neuroscience and technology, however, more and more plaintiffs are coming out of the woodwork with brain injuries. Those once-dubious, subtle brain injury claims now can be as serious as any other. Claims of “mild traumatic brain injury” (MTBI) and “post-concussive syndrome” are becoming as commonplace in the personal injury case as myofascial pain syndrome. Toxic tort plaintiffs now have a neuroscientific arsenal to prove up claims of “multiple chemical sensitivity syndrome” (MCS) and toxic encephalopathy. Today, plaintiffs alleging emotional distress or post-traumatic stress syndrome will claim that they are able to substantiate these claims with objective evidence of organic brain changes.
In 1997, the Defense Research Institute published an article examining the use of two specific diagnostic tools – PET and SPECT scans – to prove brain injuries in the context of toxic tort litigation. Brown, Brickford & Tarry, Samuel, “Does Your Pet Bite? The Misapplication of Brain Scans in Toxic Tort Litigation,” For the Defense, Vol. 39, No. 3, March 1997. The article reviewed at length the status of PET and SPECT scan technology and the shortcomings of these neuroimaging tests as reliable evidence in establishing cause-and-effect in the area of toxic torts. The article also looked at the few reported opinions that had addressed the admissibility of PET and SPECT scan evidence. While courts were divided on the question, the article concluded that (whether we as defense counsel agreed with its reliability or not) neuroimaging evidence eventually would make its way into the courtroom as it gains acceptance within the medical community and stands up to the test of time.
There has now been a request to review what has happened on the PET and SPECT scan front since 1997. The central focus is whether, in the context of a claim of toxic tort claim, PET and SPECT evidence has matured from the gray area of experimental science such that it can pass muster under Daubert. In other words, is PET/SPECT evidence now reliable? Have there been advancements either in the PET and SPECT scan technology or in the medical-scientific literature that would support the forensic use of these neuorimaging devices in the toxic tort arena? Have the past five years shown any clear trend among state and federal courts in accepting or rejecting this evidence? Does the plaintiffs’ bar appear to be honing in on the intrinsic value of PET and SPECT scans to prove toxic brain damage on behalf of clients? Does Daubert hold hope any longer for the defendant attempting to keep this evidence out?
In short, while there has been sensational progress in scientific knowledge and clinical applications of PET and SPECT since 1997, these techniques still have no place in the courtroom to substantiate cognitive dysfunction resulting from toxic exposures.
II. A Review of PET and SPECT Scan Technology
Positron Emission Tomography, otherwise known as PET, is a measure of brain function or metabolism. The basic procedure for PET scans has remained virtually unchanged in recent years. In a PET scan of the brain, a patient is injected with glucose labeled with radiopharmaceuticals or “tracers.” The brain burns glucose as fuel, so the glucose goes to where the brain is working. The glucose produces radiation giving off gamma ray signals.
As the patient lies on a table passing through a circular gamma ray scanner, PET measures the amount of physiological function in terms of glucose metabolism, and a computer reassembles the signals into color-coded images. If those parts of the brain are healthy and fully functional, they will consume a large quantity of the radioactively tagged glucose and appear as a bright orange or red color. Those parts of the brain that are damaged or simply inactive at the time of the scan will absorb little, if any, glucose, and will show up blue or purple on the finished scan. Yellows and greens are between these extremes. The colors have no intrinsic significance, but are merely a way of creating visual contrast to distinguish varying levels of metabolic activity in various parts of the brain.
Single Photon Emission Computerized Tomography, or “SPECT,” is similar in many ways to PET, but less precise. SPECT essentially measures blood flow. A radioactive chemical is administered intravenously to the patient, but the radioactive chemical remains in the bloodstream and does not enter the brain. As a result, SPECT measures brain activity indirectly by gauging cerebral “perfusion” or the brain’s vascular supply. Because damaged brain tissue normally shuts down its own blood supply, focal vascular defects on a SPECT scan may be used by a plaintiff’s attorney as circumstantial evidence of brain damage. The advantages of SPECT are that they are readily available and relatively inexpensive as compared to PET scans (the cost of a PET study typically is between $1,200 and $3,500, depending on the complexity of the study, as compared to a cost of approximately $700 for a SPECT scan).
There is no question that the use of PET and SPECT in the medical community has soared within the last five years. In 1997, there were 73 PET scanning sites in the United States, concentrated primarily in the East and Midwest. Today, there are approximately 227 PET scan centers spread across the nation. While the cost of a PET scanner (about $2 million) usually means that only the larger medical centers can afford them, they can be trailer mounted and easily transported to smaller facilities. SPECT scanners still far outnumber PET scanners.
The clinical applications for PET and SPECT have continued to expand within the fields of neurology and psychiatry. PET and SPECT imaging is used to diagnose and treat epilepsy, dementias and movement disorders (such as Parkinson’s Disease, Huntington’s Disease and Tourette Syndrome). These technologies are used in a variety of brain research applications, as in, for example, pinpointing the area of the brain responsible for ADD/ADHD in children. All of the major pharmaceutical drug manufacturers use them when applying for FDA approval of a new drug application, to show how the drug affects the metabolism and function of the human brain.
Another great stride in these technologies, particularly PET, has been the extension into the areas of cardiology and oncology. By measuring blood flow and metabolic rate within the heart, PET scans can identify the areas of decreased blood flow caused by blockages and differentiate muscle damage from living muscle. Because PET scanning can detect functional changes in cancerous cells observable structural changes occur in the tissue, PET scanning has proved to be an invaluable tool in the early detection of cancer. Oncologists rely on PET scanning also to determine the spread of cancer, whether a tumor is responding to a given course of treatment, and if a patient is free of cancer following the treatment.
There continue to be improvements and refinements to the technologies. There are better cameras and better image processing software. Practitioners and researchers are refining the methodology for administering these tests and interpreting the results. New systems are emerging. For example, GE Medical Systems now manufactures a combined PET and CT scanner which shows the anatomical location from CT along with the metabolic activity of PET in a single study. No end is in sight for the medical miracles of these technologies.
III. A Current Analysis of PET and SPECT under Daubert
Whether in the context of a toxic tort case or closed head injury, a plaintiff typically attempts to use PET or SPECT images both to prove the existence of a brain abnormality and to establish a causal link between the abnormality and the exposure or trauma. In a plaintiff’s ideal world, the images alone would establish proof of diagnosis – i.e., the plaintiff would use the scans to demonstrate that the abnormality resulted from whatever wrongful act spurred the lawsuit. The more cautious approach, and the one a plaintiff is most likely to take, is to have an expert opine that the abnormalities on brain scan are consistent with a diagnosis of toxic exposure or head trauma. Here, the plaintiff’s expert can appear to exclude all other potential causes and support his or her differential diagnosis with impressive high-tech imagery.
All too often in this day and age, a plaintiff’s lawyer whose expert faces exclusion on reliability grounds attempts to meet Daubert’s criteria with generalities. A plaintiff seeking to admit PET images to prove toxic brain damage, for example, would have the judge ignore whether this technology has been tested, subjected to peer review and accepted as reliable in this specific context. Rather, the plaintiff might point out to the court all of the wonderful medical advances in PET technology in recent years. A plaintiff can show that PET has been an established scientific methodology within the relevant medical community for now well over a decade. An abundance of published medical and scientific literature now exists on the subject of PET and SPECT, both directly and tangentially in connection with research into disease processes and their treatments.
In challenging this evidence, however, it is crucial to have the court focus on the specific purpose for which the plaintiff is seeking to introduce this evidence and to judge its admissibility in the proper context. Neither PET nor SPECT has met the acceptable levels of methodology and criteria to diagnose cognitive dysfunction due to toxic exposure. There are no articles in the published medical literature that would support this use of PET or SPECT. It is important to highlight to the court the numerous problems with accepting PET or SPECT evidence:
No standard exists for normal or abnormal. In order to attribute a specific abnormality to a specific exposure, there must be accepted scientific evaluation to establish supportable patterns of abnormalities associated with specific conditions and their causes. Not only must there be a “baseline” for normal, but there must be a database of consistent information from controlled studies showing patterns of conditions and their causes. These data still do not exist.
There is no reliable database of images acquired under the same protocol. Despite significant advances in the technology and underlying methodologies, there are significant inconsistencies from individual to individual; from scan to scan; from scanner to scanner; from interpreter to interpreter, etc. Many factors affect the quality of the image and prevent a standardized quantitative analysis on which to base any empirical study.
No theory or technique to identify specific disease processes and their causes has been identified or carried out. Again, the published scientific and medical literature to date has not advanced any theories or techniques (much less, tests or studies of any particular methodologies) that would support any conclusions regarding the effect on the brain of exposure to toxic substances. As there is no methodology in place to identify these disease processes, the potential rate of error is unknown.
No theory or technique has been subjected to peer review, nor has the scientific community accepted such a theory or technique.
The shortcomings of PET and SPECT scan evidence that existed at the time of the 1997 article remain. While medical science has made tremendous progress in the last five years, it simply has not been in the direction of establishing cause and effect in toxic exposure cases.
IV. Are Courts Letting this Evidence In?
The 1997 article discussed the handful of opinions that had addressed the admissibility of PET / SPECT evidence as of that time. One of the more notable cases was Guilbeau v. W.W. Henry Co., 85 F.3d 1149 (5th Cir. 1996). The plaintiff in that case allegedly suffered from chronic toxic encephalopathy resulting from a short-term exposure to chemicals contained in a carpet adhesive. Plaintiff offered the testimony of Dr. Thomas Callender, who testified as an expert in internal medicine, neurotoxicology and occupational medicine. Dr. Callender’s testimony was based in large part on the results of a 1990 SPECT scan which purported to show abnormal areas of decreased circulation. Despite a rigorous cross-examination exposing the lack of foundation for his testimony and the unreliability of the SPECT scan evidence, the jury returned a verdict of $2.9 million. The verdict subsequently was overturned on the ground that the product was not defective, and, consequently, we have little indication of how the Fifth Circuit may have treated the admissibility of SPECT scan evidence. Nevertheless, it is worth noting that Judge Reynado Garzo, in his dissenting opinion, expressed his belief that the plaintiff had carried his burden in proving causation through the use of SPECT scan evidence.
In another significant case, Hose v. Chicago Northwestern Transportation Co., 70 F.3d 968 (8th Cir. 1995), the trial court allowed PET scan evidence for the limited use of eliminating alternative theories of injury. Mr. Hose allegedly suffered toxic encephalopathy resulting from occupational exposure to manganese fumes. In his FELA action against his employer, the court permitted Mr. Hose’s expert to testify on the basis of a PET scan. Specifically, his expert testified that the PET scan did not match the typical patterns for Alzheimer’s, alcoholism or stroke, but, rather, showed a pattern consistent with dementia and an “overall picture. . .very consistent with manganese encephalopathy and toxicity as the cause of this dementia.” The judge allowed this testimony despite his admission that the scientific literature did not explain how manganese toxicity would appear on a PET scan. The jury returned a $1.33 million verdict. On appeal, the Eighth Circuit upheld the verdict and held that the trial court did not abuse its discretion in allowing the PET scan evidence. The Eighth Circuit’s opinion relied to a great extent on the fact that the expert’s testimony was limited to showing consistency with, as opposed to diagnostic proof of, manganese encephalopathy.
In another FELA action alleging multiple chemical sensitivity syndrome, however, a trial court excluded an expert’s testimony which relied heavily on SPECT images. Summers v. Missouri Pacific Railroad System, 897 F. Supp. 533 (E.D. Okla. 1995). The court in that case noted the lack of reliable scientific and medical data to support the use of SPECT technology to diagnose neuorotoxic exposure.
Since 1997, there has been only one reported opinion squarely addressing this issue in the context of a claimed toxic exposure. In Rhilinger v. Jancics, et al., 1998 WL 1182058 (Mass. Super. 1998), a Massachusetts trial court allowed a plaintiff’s expert to testify as to the results of a SPECT test to prove injuries consistent with toxic encephalopathy. Ms. Rhilinger alleged that she developed toxic solvent encephalopathy from exposure to chemicals stored illegally in the basement of her apartment building. She asserted that the chemicals leaked and caused a migration of fumes into her residence which ultimately caused brain damage. After she experienced various physical and cognitive symptoms including fatigue, dizziness, memory loss, hoarseness and stuttering in her speech, she was seen by a Dr. Howard Hu at the Center for Occupational and Environmental Medicine at the Massachusetts Respiratory Hospital. Dr. Hu diagnosed Ms. Rhilinger with toxic encephalopathy.
The defendants brought a Daubert challenge to the admissibility of the SPECT scan evidence on three grounds, namely, that the use of SPECT scan imaging to diagnose brain injury due to chemical exposure (1) is not supported by valid scientific evidence; (2) has not been subjected to empirical testing or otherwise properly tested or studied; and (3) has not been generally accepted as a diagnostic tool for toxic encephalopathy in the relevant scientific and medical communities.
The court included a thorough discussion of SPECT scans, and noted that the medical community had used SPECT technology for at least 15 years. The court acknowledged that, as of that time, there was inadequate evidence to support the use of SPECT scans to establish the existence of a cause and effect relationship in toxic exposure cases. Indeed, the plaintiff’s own doctor testified that a SPECT scan could not be relied upon as definitive evidence to rule in or to rule out a diagnosis of TSE. Nevertheless, the court relied on Dr. Hu’s testimony that: (1) “individuals who have a history of exposure to chemicals are at a higher risk of having abnormal SPECT scan results”; (2) Ms. Rhilinger’s SPECT scan results were consistent with the results of those individuals; (3) Ms. Rhilinger had no other identifiable disease process or diagnosis to account for her abnormal SPECT scan results; and, (4) her MRI was normal, thus ruling out other possible origins of her cognitive difficulties.
In holding that the SPECT evidence was admissible, the court stated that:
There is no dispute that SPECT scans show abnormalities in brain function. Neither is there a dispute that SPECT scans cannot conclusively establish the existence or non-existence of TSE in a patient. Plaintiff’s experts do not opine that the SPECT scan does, in fact, establish the diagnosis. They merely assert that is one of a constellation of diagnostic tools which they used and considered consistent with their conclusion that Rhilinger suffers from TSE.
There also is no dispute that SPECT scanning is relevant to prove or disprove the other possible explanations for plaintiff’s condition. The scientific evidence submitted by both parties approves of the use of SPECT scans to identify other brain disorders such as epilepsy, stroke and dementia. Plaintiff’s proffered expert testimony does not go beyond what is considered scientifically defensible use of SPECT scan technology.
The judge held that SPECT evidence is “scientifically reliable” in such a toxic tort case. Thus, as in the Hose case, the plaintiff got in her SPECT evidence in a round-about way by using it to show a diagnosis “consistent with” toxic exposure.
The debate over the admissibility of PET/SPECT evidence has also been addressed in a number of other contexts during the last few years. Penney v. Praxair, 116 F.3d 330 (8th Cir. 1997), for example, involved a claim of brain injuries following an automobile accident. The 62-year-old plaintiff allegedly suffered a whiplash-type injury and claimed symptoms including headaches, dizziness, vertigo, ringing ears, a sore neck and various other maladies. He underwent both an MRI and a CT scan, neither of which showed any brain injury. The plaintiff then had a PET scan which, according to his expert, revealed “abnormalities which were consistent with a traumatic brain injury.” 116 F.3d at 332. The district court refused to admit the PET scan evidence, reasoning that it would “not be helpful to the jury in deciding the issues when compared with the likelihood that the jury would misapply the evidence.” Id. On appeal, the Eighth Circuit upheld the district court ruling. The appellate court’s analysis is instructive on some of the problems with the numerous variables affecting PET scan evidence. Specifically, plaintiff’s expert failed to account for the plaintiff’s age and medication taken days before the procedure, and the expert could not explain how plaintiff’s abnormalities compared to a control group of individuals with similar characteristics.
In re Air Crash at Little Rock Arkansas, 291 F.3d 503 (8th Cir. 2002) involved a dispute over whether post-traumatic stress disorder is in itself a “physical injury” for which recovery under the Warsaw Convention was allowed. The Eighth Circuit rejected as speculative the testimony of plaintiff’s expert to the effect that “people with chronic PTSD may have brain dysfunction, meaning that PTSD is both biological and physical.” Id. at 511. While this case did not deal with the admissibility of PET or SPECT evidence, it bears mentioning because the Eighth Circuit noted in its opinion that the plaintiff failed to have one of these tests performed to confirm the existence of a physical injury. Thus, the Eighth Circuit seemed to indicate that a PET or SPECT just might have proved the requisite physical injury from PTSD.
The admissibility of PET / SPECT scan evidence arises most frequently in the criminal context, typically as defendants attempt to introduce neuroimaging evidence to negate or mitigate criminal intent, or to show incompetence to stand trial. See, e.g., United States v. Mezvinsky, 206 F.Supp.2d 661 (E.D.Pa. 2002) (rejecting defendant’s attempt to prove “insanity” defense through PET scan evidence); Jackson v. Calderon, 211 F.2d 1148 (9th Cir. 2000) (rejecting habeas petitioner’s attempt to use PET scan evidence to show chronic PCP abuse at time of criminal act). While these cases are not directly on point, they are nevertheless instructive in showing how courts are addressing some of the evidentiary shortcomings found with PET/SPECT scan evidence.
In a line of cases right out of last season’s The Sopranos, Vincent “The Chin” Gigante (reputed head of the Genovese crime family) repeatedly attempted to use PET scan images to show that he was incompetent to stand trial which the Southern District of New York rejected. In United States v. Gigante, 982 F.Supp. 140 (S.D.N.Y. 1997), the court refused to admit the testimony of Dr. Monte Buchsbaum of New York’s Mount Sinai Medical School. Dr. Buchsbaum opined that a PET scan would allow him to “measure where and how much brain activity occurred,” and further opined that Mr. Gigante’s PET scan revealed “organic brain dysfunction, possibly due to Alzheimer’s disease or multi-infarct dementia.” Id. at 147. The district court rejected this testimony, highlighting several recurring shortcomings with PET scan evidence:
No baseline – Dr. Buchsbaum had never reviewed earlier PET scans of the defendant, so he was unable to state reliably whether the recent PET scan revealed new dementia or dementia that had existed all along.
Control group – the doctor compared the defendant’s PET scan to a fairly small control group, so the comparison was not necessarily statistically-significant.
Variables / Medication – the defendant was taking medication when his PET scan was conducted, and the doctor failed to explain whether the PET scan results were affected by the medication, or whether people in the control group were also taking similar medication when their PET scans were conducted.
See also United States v. Gigante, 996 F.Supp. 194 (S.D.N.Y. 1998) (rejecting Mr. Gigante’s second attempt to introduce PET scan evidence). The shortcomings on which the trial court focused are essentially some of the same that arise in the toxic tort context.
In sum, no clear trend has emerged among the courts of accepting or rejecting PET and SPECT scans. In certain instances – even when confronted with the evidence that this technology has not met acceptable scientific levels of methodology and criteria to diagnose neuro-toxic injuries – courts are letting it in, even if only for the limited purpose of showing a differential diagnosis and injuries “consistent with” toxic exposure. As alluded to in the 1997 article, the hidden danger in all of this remains that, to the average juror, a PET or SPECT scan is as “objective” as a photograph and suggests scientific reliability where there is none.
V. The Next Five Years and Beyond
The few reported cases might suggest that plaintiffs’ lawyers have not taken an interest in pursuing these technologies in toxic tort and personal injury litigation. As the recent proliferation of attorney websites shows, however, these technologies are fast becoming common weapons in the plaintiff’s arsenal. Numerous plaintiffs’ websites advertise their successful use of PET and SPECT scan technology in pursing mild traumatic brain injury and toxic brain injury claims on behalf of clients. (See, e.g., www.braininjurylaw.com; www.headinjurylaw.com; www.themoldsource.com). The subject has been a hot topic in recent years at ATLA conventions and in other plaintiffs’ networks.
Undoubtedly, the plaintiffs’ bar will continue the push to make claimed diseases like multiple chemical sensitivity a household name. Plaintiffs will make inroads into altogether new areas of toxic tort. We can expect to see more and more reliance on PET and SPECT scans and all of the latest in neuroimaging evidence to support these claims.
As is often the case, we may one day see a sector of medical science following the lead of the plaintiffs’ bar to provide the needed methodologies, controls, empirical evidence and so forth to enable PET and SPECT scans to prove neuro-toxic injuries. Until then, PET and SPECT scans simply have no place in a toxic tort trial.