Integration of [11C]Methionine-Positron Emission Tomographic and Magnetic Resonance Imaging for Image-guided Surgical Resection of Infiltrative Low-grade Brain Tumors in Children

Predicting outcome following mild traumatic brain injury: protocol for the longitudinal, prospective, observational Concussion Recovery (CREST) cohort study

INTRODUCTION

Mild traumatic brain injury (mTBI) is a complex injury with heterogeneous physical, cognitive, emotional and functional outcomes. Many who sustain mTBI recover within 2 weeks of injury; however, approximately 10%-20% of individuals experience mTBI symptoms beyond this 'typical' recovery timeframe, known as persistent post-concussion symptoms (PPCS). Despite increasing interest in PPCS, uncertainty remains regarding its prevalence in community-based populations and the extent to which poor recovery may be identified using early predictive markers.

OBJECTIVE

(1) Establish a research dataset of people who have experienced mTBI and document their recovery trajectories; (2) Evaluate a broad range of novel and established prognostic factors for inclusion in a predictive model for PPCS.

METHODS AND ANALYSIS

The Concussion Recovery Study (CREST) is a prospective, longitudinal observational cohort study conducted in Perth, Western Australia. CREST is recruiting adults aged 18-65 from medical and community-based settings with acute diagnosis of mTBI. CREST will create a state-wide research dataset of mTBI cases, with data being collected in two phases. Phase I collates data on demographics, medical background, lifestyle habits, nature of injury and acute mTBI symptomatology. In Phase II, participants undergo neuropsychological evaluation, exercise tolerance and vestibular/ocular motor screening, MRI, quantitative electroencephalography and blood-based biomarker assessment. Follow-up is conducted via telephone interview at 1, 3, 6 and 12 months after injury. Primary outcome measures are presence of PPCS and quality of life, as measured by the Post-Concussion Symptom Scale and the Quality of Life after Brain Injury questionnaires, respectively. Multivariate modelling will examine the prognostic value of promising factors.

ETHICS AND DISSEMINATION

Human Research Ethics Committees of Royal Perth Hospital (#RGS0000003024), Curtin University (HRE2019-0209), Ramsay Health Care (#2009) and St John of God Health Care (#1628) have approved this study protocol. Findings will be published in peer-reviewed journals and presented at scientific conferences.

TRIAL REGISTRATION NUMBER

ACTRN12619001226190.

Neurocognitive performance and mental health of retired female football players compared to non-contact sport athletes

Background

Adverse long-term effects of playing football due to repetitive head impact exposure on neurocognition and mental health are controversial. To date, no studies have evaluated such effects in women.

Aims

To (1) compare neurocognitive performance, cognitive symptoms and mental health in retired elite female football players (FB) with retired elite female non-contact sport athletes (CON), and to (2) assess whether findings are related to history of concussion and/or heading exposure in FB.

Methods

Neurocognitive performance, mental health and cognitive symptoms were assessed using computerised tests (CNS-vital signs), paper pen tests (Category fluency, Trail-Making Test, Digit Span, Paced Auditory Serial Addition Test), questionnaires (Hospital Anxiety and Depression Scale, SF-36v2 Health Survey) and a symptom checklist. Heading exposure and concussion history were self-reported in an online survey and in a clinical interview, respectively. Linear regression was used to analyse the effect of football, concussion and heading exposure on outcomes adjusted for confounders.

Results

FB (n=66) performed similar to CON (n=45) on neurocognitive tests, except for significantly lower scores on verbal memory (mean difference (MD)=−7.038, 95% CI −12.98 to –0.08, p=0.038) and verbal fluency tests (MD=−7.534, 95% CI –13.75 to –0.46, p=0.016). Among FB weaker verbal fluency performance was significantly associated with ≥2 concussions (MD=−10.36, 95% CI –18.48 to –2.83, p=0.017), and weaker verbal memory performance with frequent heading (MD=−9.166, 95% CI –17.59 to –0.123, p=0.041). The depression score differed significantly between study populations, and was significantly associated with frequent heading but not with history of concussion in FB.

Conclusion

Further studies should investigate the clinical relevance of our findings and whether the observed associations point to a causal link between repetitive head impacts and verbal memory/fluency or mental health.

Consent, capacity and compliance in concussion management: cave ergo medicus (let the doctor beware)

While the acute effects of concussion and mild traumatic brain injury (TBI) are well understood, the certainty in the medical literature regarding the long-term outcomes of sports-related concussion is limited. Long-term deficits that may result from single, repeated concussions, and possibly subconcussive impacts, include cognitive dysfunction, depression and executive dysfunction. Perhaps most troublingly, repetitive head impacts have been linked to neurodegenerative diseases, including chronic traumatic encephalopathy (CTE), although the precise risk of long-term consequences remains unknown. CTE represents a distinct tauopathy with an unknown incidence in athletic populations; however, a cause and effect relationship has not yet been demonstrated between CTE and concussions or between CTE and exposure to contact sports, as no prospective longitudinal studies have been performed to address that question. Studies of high-school sports exposure and long-term outcomes have not demonstrated consistent findings.Medical advice regarding return to play and the risk of acute and/or long-term consequences is therefore problematic. It is important that the individual's right to make their own choices regarding their health is respected. Team, coach, parental, peer or financial pressures should not influence this decision. The choice to return to play after a concussion or mild TBI injury is the athlete's decision once they have (1) recovered from their injury and have the legal capacity to make an informed decision; (2) been medically assessed and (3) been informed of any possible long-term risks in a language that they can understand.Given the current lack of certainty in relation to long-term outcomes from concussion, is it possible to provide a framework to inform players of current evidence, as part of a consent process, even if the information upon which the decision to return to sport is based remains uncertain and evolving?

Orthopaedic and brain injuries over last 10 seasons in the National Football League (NFL): number and effect on missed playing time

Objective

To examine trends in number and seriousness of major injuries in the National Football League (NFL) over seasons 2010–2019 and the effect of rule changes to injuries to the leg, back, arm and head.

Methods

We calculated, from publicly available weekly injury reports, the number of players that were injured and playing time missed, that is, the number of weeks on average that an injured player had to sit out, as a function of injury to a specific body part. Using classical time series analysis techniques, we fitted injury data with linear and non-linear functions.

Results

The number of major injuries to the leg, back, arm and head has not declined over the last 10 years. During this time period, time missed because of injuries to the head has shown a significantly increasing trend. Rule changes designed specifically to protect arm or head have, respectively, succeeded in shortening the time that the injured player misses, but the impact lasts only over a single season.

Conclusions

Overall, our data support the argument that new, well-intentioned rules adopted every season by the NFL have been proven to be too weak to make the NFL game safer. Broad-based management of brain and orthopaedic injuries and adoption of preventative measures to reduce the number of players injured and the seriousness of their injuries are required in the modern NFL.

Football's InfluencE on Lifelong health and Dementia risk (FIELD): protocol for a retrospective cohort study of former professional footballers

INTRODUCTION

In the past decade, evidence has emerged suggesting a potential link between contact sport participation and increased risk of late neurodegenerative disease, in particular chronic traumatic encephalopathy. While there remains a lack of clear evidence to test the hypothesis that contact sport participation is linked to an increased incidence of dementia, there is growing public concern regarding the risk. There is, therefore, a pressing need for research to gain greater understanding of the potential risks involved in contact sports participation, and to contextualise these within holistic health benefits of sport.

METHODS AND ANALYSIS

Football's InfluencE on Lifelong health and Dementia risk is designed as a retrospective cohort study, with the aim to analyse data from former professional footballers (FPF) in order to assess the incidence of neurodegenerative disease in this population. Comprehensive electronic medical and death records will be analysed and compared with those of a demographically matched population control cohort. As well as neurodegenerative disease incidence, all-cause, and disease-specific mortality, will be analysed in order to assess lifelong health. Cox proportional hazards models will be run to compare the data collected from FPFs to matched population controls.

ETHICS AND DISSEMINATION

Approvals for study have been obtained from the University of Glasgow College of Medical, Veterinary and Life Sciences Research Ethics Committee (Project Number 200160147) and from National Health Service Scotland's Public Benefits and Privacy Panel (Application 1718-0120).

Concussion assessment in the emergency department: a preliminary study for a quality improvement project

Background

In sport, concussion is assessed using the Sports Concussion Assessment Tool (SCAT) 5 and managed with return to play guidelines. Similar, user-friendly tools are rarely, if ever, used in the emergency department (ED).

Objectives

To evaluate a modified concussion assessment tool designed for the ED (ED-CAT) in patients presenting with a head injury and to identify variables that predict 30-day reattendance.

Methods

A preliminary, prospective, evaluation in a quality improvement project was conducted in one hospital in South Wales. Patients were recruited if they were over 13 years, and either did not have an ED-CT head scan or had a scan with no acute changes. The primary outcome was 30-day reattendance.

Results

40 patients were recruited, 18 of whom had a CT scan. 37 were discharged on the same day with advice, two discharged the next day and one was admitted. Three (7.5%) patients reattended the department. Predictors of reattendance were headache score (median 3.0 vs 5.0; p<0.05), pressure in head score (2.0 vs 5.0; p<0.05), nausea/vomiting score (1.0 vs 3.0; p<0.05), dizziness score (1.0 vs 4.0; p<0.05), blurred vision score (0 vs 4.0; p<0.01), balance problems score (0 vs 4.0; p<0.05), sensitivity to light and confusion score (0 vs 4.0; p<0.01), orientation score (1. 0 vs 0; p<0.05) and immediate memory score (5.0 vs 4.0; p<0.05).

Conclusions

Key symptoms and signs predicted 30-day reattendance. The ED-CAT requires validation and refinement in a larger population to produce a short, practical, user-friendly, relevant tool for ED head injury assessment.

Comparison of branded rugby headguards on their effectiveness in reducing impact on the head

Aim

To compare the available brands of rugby headguards and evaluate their impact attenuation properties at various locations on the cranium, with regard to concussion prevention.

Methods

Seven different branded headguards were fitted onto a rigid headform and drop-tested in three different positions. An accelerometer measured the linear acceleration the headform experienced on impact with the ground. Each test involved dropping the headform from a height that generated 103.8 g on average when bare, which is the closest acceleration to the upper limit of the concussion threshold of 100 g. A mean peak acceleration for each drop position was calculated and compared with the bare baseline measurement.

Results

Each headguard demonstrated a significant decrease in the mean peak acceleration from the baseline value (all p≤0.01). Overall the Canterbury Ventilator was the most effective headguard, decreasing the impact force on average by 47%. The least effective was the XBlades Elite headguard, averaging a force reduction of 27%. In five of the seven headguards, the right side of the headwear was the most effective at reducing impact force.

Conclusion

Overall, the results indicate that it would be beneficial to wear a headguard during rugby in order to reduce the impact forces involved in head collisions. There was also a clear difference in performance between the tested brands, establishing the Canterbury headguard as the most effective. However, only one model of headguard from each brand was tested, so further research evaluating all other models should be considered.

Amide proton transfer imaging seems to provide higher diagnostic performance in post-treatment high-grade gliomas than methionine positron emission tomography

OBJECTIVES

To compare the diagnostic performance of amide proton transfer (APT) imaging and 11-C methionine positron emission tomography (MET-PET) for in vivo molecular imaging of protein metabolism in post-treatment gliomas.

MATERIALS AND METHODS

This study included 43 patients (12 low and 31 high grade) with post-treatment gliomas who underwent both APT and MET-PET imaging within 3 weeks. APT-weighted voxel values and semi-quantitative tumour-to-normal ratios (TNR) were obtained from tumour portions. The voxel-wise relationships between TNR and APT were assessed. The diagnostic performance for recurrence of high-grade gliomas was calculated, using the area under the receiver operating characteristic curve (AUC) with maximum (TNR_max and APT_max) and 90% histogram values (TNR90 and APT90).

RESULTS

A moderate positive correlation between TNR and APT was found in low-grade recurrences (r = 0.47, p < 0.001), but not in high-grade ones (r = -0.24, p < 0.001). For distinguishing recurrence in post-treatment high-grade gliomas, APT_max (AUC, 0.88) and APT90 (AUC, 0.78-0.83) had a similar to better diagnostic performance than TNR_max (AUC, 0.71, p = 0.08) or TNR90 (AUC, 0.53-0.59, p = 0.01-0.05).

CONCLUSIONS

In post-treatment high-grade gliomas, APT provides different regional information to MET-PET and provides higher diagnostic performance. This difference needs to be considered when using APT or MET-PET as a surrogate marker for tumour protein metabolism.

KEY POINTS

• APT and TNR values in low-grade recurrence showed a moderate voxel-wise correlation. • APT and TNR demonstrated regional differences in post-treatment high-grade gliomas. • APT90 showed better diagnostic performance than TNR90 in high-grade recurrence.

Memory loss: Five new things

PURPOSE OF REVIEW

Memory loss can be due to a wide variety of causes. We provide new information about the biology of common genetic and acquired causes of memory loss in older adults.

RECENT FINDINGS

New data are available about the genetics of Alzheimer disease (AD), dementia with Lewy bodies (DLB), and frontotemporal dementia. Amyloid PET, FDG-PET, and MRI have improved our understanding of how mild cognitive impairment evolves to AD. Several studies have shown links between concussion and chronic traumatic encephalopathy. Healthy eating and regular exercise have been demonstrated to slow cognitive decline in older adults. Randomized trials continue to show benefits for cholinesterase inhibitors and memantine in patients with AD and DLB.

SUMMARY

New causes of memory loss are still being identified. More sophisticated diagnostic tools have improved our ability to make earlier diagnoses in older adults with memory loss.

Chronic Repetitive Mild Traumatic Brain Injury Results in Reduced Cerebral Blood Flow, Axonal Injury, Gliosis, and Increased T-Tau and Tau Oligomers

Exposure to repetitive mild traumatic brain injury (mTBI) is a risk factor for chronic traumatic encephalopathy, which is characterized by patchy deposition of hyperphosphorylated tau aggregates in neurons and astrocytes at the depths of cortical sulci. We developed an mTBI paradigm to explore effects of repetitive concussive-type injury over several months in mice with a human tau genetic background (hTau). Two injuries were induced in the hTau mice weekly over a period of 3 or 4 months and the effects were compared with those in noninjured sham animals. Behavioral and in vivo measures and detailed neuropathological assessments were conducted 6 months after the first injury. Our data confirm impairment in cerebral blood flow and white matter damage. This was accompanied by a 2-fold increase in total tau levels and mild increases in tau oligomers/conformers and pTau (Thr231) species in brain gray matter. There was no evidence of neurofibrillary/astroglial tangles, neuropil threads, or perivascular foci of tau immunoreactivity. There were neurobehavioral deficits (ie, disinhibition and impaired cognitive performance) in the mTBI animals. These data support the relevance of this new mTBI injury model for studying the consequences of chronic repetitive mTBI in humans, and the role of tau in TBI.

Chronic traumatic encephalopathy: a potential late and under recognized consequence of rugby union?

The association between exposure to head injury and increased risk of neurodegenerative disease, specifically chronic traumatic encephalopathy (CTE), is widely recognized. Historically, this was largely considered a phenomenon restricted to boxers, with more recent case series identifying further 'high risk' individuals, such as former American footballers, or military personnel. However, in all cases thus far reported, it is clear that it is the exposure to head injury which is associated with increased dementia risk, and not the circumstances or environment of exposure. As such, there is considerable potential for under-recognition of CTE in patients presenting with neurodegenerative disease, particularly where head injury exposure might have been historical and through sport. This article reviews current understanding of CTE and, via an illustrative case in rugby union, highlights the value of a detailed history on head injury and also draws attention to imaging studies in assessing patients with neurodegenerative disease.

Chronic traumatic encephalopathy and athletes

Recent case reports have described athletes previously exposed to repetitive head trauma while participating in contact sports who later in life developed mood disorders, headaches, cognitive difficulties, suicidal ideation, difficulties with speech, and aggressive behavior. Postmortem discoveries show that some of these athletes have pathologic findings that are collectively termed chronic traumatic encephalopathy (CTE). Current hypotheses suggest that concussions or perhaps blows to the head that do not cause the signs and symptoms necessary for making the diagnosis of concussion, so-called subconcussive blows, cause both the clinical and pathologic findings. There are, however, some athletes who participate in contact sports who do not develop the findings ascribed to CTE. Furthermore, there are people who have headaches, mood disorders, cognitive difficulties, suicidal ideation, and other clinical problems who have neither been exposed to repeated head trauma nor possessed the pathologic postmortem findings of those currently diagnosed with CTE. The current lack of prospective data and properly designed case-control studies limits the current understanding of CTE, leading to debate about the causes of the neuropathologic findings and the clinical observations. Given the potential for referral and recall bias in available studies, it remains unclear whether or not the pathologic findings made postmortem cause the presumed neurobehavioral sequela and whether the presumed risk factors, such as sports activity, cerebral concussions, and subconcussive blows, are solely causative of the clinical signs and symptoms. This article discusses the current evidence and the associated limitations.

The usefulness of dynamic O-(2-18F-fluoroethyl)-L-tyrosine PET in the clinical evaluation of brain tumors in children and adolescents

Experience regarding O-(2-(18)F-fluoroethyl)-L-tyrosine ((18)F-FET) PET in children and adolescents with brain tumors is limited.

METHODS

Sixty-nine (18)F-FET PET scans of 48 children and adolescents (median age, 13 y; range, 1-18 y) were analyzed retrospectively. Twenty-six scans to assess newly diagnosed cerebral lesions, 24 scans for diagnosing tumor progression or recurrence, 8 scans for monitoring of chemotherapy effects, and 11 scans for the detection of residual tumor after resection were obtained. Maximum and mean tumor-to-brain ratios (TBRs) were determined at 20-40 min after injection, and time-activity curves of (18)F-FET uptake were assigned to 3 different patterns: constant increase; peak at greater than 20-40 min after injection, followed by a plateau; and early peak (≤ 20 min), followed by a constant descent. The diagnostic accuracy of (18)F-FET PET was assessed by receiver-operating-characteristic curve analyses using histology or clinical course as a reference.

RESULTS

In patients with newly diagnosed cerebral lesions, the highest accuracy (77%) to detect neoplastic tissue (19/26 patients) was obtained when the maximum TBR was 1.7 or greater (area under the curve, 0.80 ± 0.09; sensitivity, 79%; specificity, 71%; positive predictive value, 88%; P = 0.02). For diagnosing tumor progression or recurrence, the highest accuracy (82%) was obtained when curve patterns 2 or 3 were present (area under the curve, 0.80 ± 0.11; sensitivity, 75%; specificity, 90%; positive predictive value, 90%; P = 0.02). During chemotherapy, a decrease of TBRs was associated with a stable clinical course, and in 2 patients PET detected residual tumor after presumably complete tumor resection.

CONCLUSION

Our findings suggest that (18)F-FET PET can add valuable information for clinical decision making in pediatric brain tumor patients.

The use of functional magnetic resonance imaging in reducing a risk of postoperative neurological deficits in the patients with brain tumour

BACKGROUND AND PURPOSE

The purpose of the study was to compare the results of operative treatment of tumours located in the sensory-motor cortex guided with functional magnetic resonance imaging (fMRI) combined with the neuro-na-vigation system to the results of classical operative treatment.

MATERIAL AND METHODS

The studied group comprised 28 pa-tients with a tumour located in the sensory-motor cortex area who underwent surgery guided with fMRI and the neuro-na-vigation system. A control group comprised 30 patients with the same clinical diagnosis, operated on without functional neuronavigation.

RESULTS

The use of functional neuronavigation allowed for an 18% reduction in the intensity of neurological deficits after surgical treatment in patients from the studied group, compared to the subjects from the control group (p = 0.0001). In the patients with diagnosed high-grade glioma, improvement in the neurological condition in the studied group was 16% (p = 0.03). The initial neurological condition and the results of surgical treatment in patients with a tumour located less than 5 mm from the sensory-motor cortex, determined in fMRI examination, are worse than in patients with a tumour located more than 5 mm.

CONCLUSIONS

In patients with a diagnosed brain tumour in the sensory-motor cortex who have neurological deficits, fMRI provides valuable imaging data on active areas. Tumour location of more than 5 mm from the fMRI active area of the sensory-motor cortex is connected with a considerably lower risk of postoperative neurological deficits. Removing a tumour in the sensory-motor cortex region, guided with fMRI and the neuronavigation system, considerably lowers the risk of postoperative development or exacerbation of neurological deficits.

Evaluation of children with craniopharyngioma using carbon-11 methionine PET prior to proton therapy

BACKGROUND

Fluorine-18 ((18)F) fluorodeoxyglucose (FDG) positron emission tomography (PET) is limited in its evaluation of brain tumors due to the high basal activity of the cerebral cortex and white matter. Carbon-11 methionine ((11)C MET) has little uptake under normal conditions. We prospectively investigated the uptake of (18)F FDG and (11)C MET PET in patients with craniopharyngioma prior to proton therapy.

METHODS

Ten patients newly diagnosed with craniopharyngioma underwent PET imaging using (18)F FDG and (11)C MET. PET and MRI studies were registered to help identify tumor volume. Measurements of maximum standardized uptake value (SUV(max)) were taken of the tumor and compared with noninvolved left frontal background white matter using a paired t-test. Uptake was graded using a 4-point scale.

RESULTS

Median patient age was 9 years (range 5-19). Seven patients were diagnosed by pathology, 1 by cyst fluid aspiration, and 2 by neuroimaging. Median FDG SUV(max) for tumor and background were 2.65 and 3.2, respectively. Median MET SUV(max) for tumor and background were 2.2 and 1, respectively. There was a significant difference between MET tumor SUV(max) and MET background SUV(max) (P = .0001). The difference between FDG tumor SUV(max) and FDG background SUV(max) was not significant (P = .3672).

CONCLUSION

(11)C MET PET uptake is significantly greater within the tumor compared with noninvolved background white matter, making it more useful than FDG PET in identifying active tumor in patients with craniopharyngioma. Future work will focus on using (11)C MET PET to discriminate between active and inactive tumor after irradiation.

Assessment of treatment response in patients with glioblastoma using O-(2-18F-fluoroethyl)-L-tyrosine PET in comparison to MRI

The assessment of treatment response in glioblastoma is difficult with MRI because reactive blood-brain barrier alterations with contrast enhancement can mimic tumor progression. In this study, we investigated the predictive value of PET using O-(2-(18)F-fluoroethyl)-l-tyrosine ((18)F-FET PET) during treatment.

METHODS

In a prospective study, 25 patients with glioblastoma were investigated by MRI and (18)F-FET PET after surgery (MRI-/FET-1), early (7-10 d) after completion of radiochemotherapy with temozolomide (RCX) (MRI-/FET-2), and 6-8 wk later (MRI-/FET-3). Maximum and mean tumor-to-brain ratios (TBR(max) and TBR(mean), respectively) were determined by region-of-interest analyses. Furthermore, gadolinium contrast-enhancement volumes on MRI (Gd-volume) and tumor volumes in (18)F-FET PET images with a tumor-to-brain ratio greater than 1.6 (T(vol 1.6)) were calculated using threshold-based volume-of-interest analyses. The patients were grouped into responders and nonresponders according to the changes of these parameters at different cutoffs, and the influence on progression-free survival and overall survival was tested using univariate and multivariate survival analyses and by receiver-operating-characteristic analyses.

RESULTS

Early after completion of RCX, a decrease of both TBR(max) and TBR(mean) was a highly significant and independent statistical predictor for progression-free survival and overall survival. Receiver-operating-characteristic analysis showed that a decrease of the TBR(max) between FET-1 and FET-2 of more than 20% predicted favorable survival [corrected], with a sensitivity of 83% and a specificity of 67% (area under the curve, 0.75). Six to eight weeks later, the predictive value of TBR(max) and TBR(mean) was less significant, but an association between a decrease of T(vol 1.6) and PFS was noted. In contrast, Gd-volume changes had no significant predictive value for survival.

CONCLUSION

In contrast to Gd-volumes on MRI, changes in (18)F-FET PET may be a valuable parameter to assess treatment response in glioblastoma and to predict survival time.

¹¹C-methionine uptake and intraoperative 5-aminolevulinic acid-induced fluorescence as separate index markers of cell density in glioma: a stereotactic image-histological analysis

BACKGROUND

The extent of tumor resection is acknowledged as 1 of the prognostic factors for glioma. 5-Aminolevulinic acid (5-ALA)-induced fluorescence guidance and neuronavigation integrated with (11) C-methionine positron emission tomography (PET) are widely utilized under the expectation of improving the extent of resection. These 2 novel approaches are beneficial for glioma resections, and the combination of these approaches appears rational. However, biological characteristics reflecting 5-ALA-induced fluorescence and (11) C-methionine uptake have not been clearly elucidated, and studies about the relationship between 5-ALA-induced fluorescence and (11) C-methionine uptake have been limited. The present study aimed to clarify this issue.

METHODS

Data from 11 consecutive patients harboring astrocytic tumors were analyzed: 2 grade II and 2 grade III, and 7 grade IV tumors were included. Thirty samples from these patients were obtained from the relative periphery of each tumor. Relationships among histology, 5-ALA-induced fluorescence and (11) C-methionine uptake were analyzed by stereotactic sampling and image analysis.

RESULTS

Uptake of (11) C-methionine correlated with cell density (R(2) = 0.322, P = .0059). Cell density was higher in fluorescence-positive areas than in negative areas (2760 ± 1080 vs 1450 ± 1380/mm(2) , P = .0132). Although both (11) C-methionine uptake and fluorescence seemed to correlate with cell density, no significant difference in (11) C-methionine uptake was seen between fluorescence-positive and -negative areas (P = .367). Multiple linear regression analysis revealed (11) C-methionine uptake and 5-ALA-induced fluorescence as independent indices for tumor cell density.

CONCLUSIONS

These results indicate that 5-ALA fluorescence and (11) C-methionine PET image are separate index markers for cytoreduction surgery of gliomas.

Principles and Application of PET in Brain Tumors

For tumors of the central nervous system (CNS), the ability to accurately delineate the extent of tumor has implications for diagnosis, prognosis, and treatment. PET, mainly with (18)F-fluorodeoxyglucose (FDG), has become commonplace in the work-up of many extracranial tumors. However, the relative high background of FDG-PET activity of normal brain tissue has limited the applicability of this modality in CNS tumors to date. More recently, novel PET tracers for imaging of CNS tumors have been developed. This article outlines recent advances in PET as a complementary imaging modality with implications for diagnosis, prognosis, surgical and radiation treatment planning, and post-therapy surveillance in malignancies of the CNS. Pharmacokinetic properties of the radiotracers and the influence of blood-brain-barrier integrity are also incorporated into the discussion.

Are stereotactic sample biopsies still of value in the modern management of pineal region tumours? Lessons from a single-department, retrospective series

OBJECTIVE

Recent improvements in imaging-based diagnosis, the broader application of neuroendoscopic techniques and advances in open surgery techniques mean that the need for stereotactic biopsies in the management of pineal region tumours must be reevaluated. The primary aim of this retrospective study was to establish whether stereotactic biopsy is still of value in the modern management of pineal region tumours.

METHODS

From 1985 to 2009, 88 consecutive patients underwent a stereotactic biopsy in our institution (51 males and 37 females; median age at presentation 30; range 2-74).

RESULTS

Accurate tissue diagnoses were obtained in all but one case (i.e. 99%). In one case (1%), three distinct stereotactic procedures were necessary to obtain a tissue diagnosis. There was no mortality or permanent morbidity associated with stereotactic biopsy. One patient (1%) presented an intra-parenchymal hematoma but no related clinical symptoms. Five patients (6%) presented transient morbidity, which lasted for between 2 days and 3 weeks after the biopsy.

CONCLUSIONS

To guide subsequent treatment, we believe that histological diagnosis is paramount. Stereotactic biopsies are currently the safest and the most efficient way of obtaining this essential information. Recent improvements in stereotactic technology (particularly robotic techniques) appear to be very valuable, with almost no permanent morbidity or mortality risk and no decrease in the accuracy rate. In our opinion, other available neurosurgical techniques (such as endoscopic neurosurgery, stereotactic neurosurgery and open microsurgery) are complementary and not competitive.

Clinical impact of integrating positron emission tomography during surgery in 85 children with brain tumors

OBJECT

In this paper, the authors' goal was to evaluate the impact of PET information on brain tumor surgery in children.

METHODS

Between 1995 and 2007, 442 children were referred to the authors' institution for a newly diagnosed brain lesion. Of these, 85 were studied with FDG-PET and/or L-(methyl-(11)C)-methionine -PET in cases in which MR images were unable to assist in selecting accurate biopsy targets (35 patients) or to delineate tumors for maximal resection (50 patients). In surgical cases, PET and MR images were combined in image fusion planning for stereotactic biopsies or navigation-based resections. The preoperative planning images were compared postoperatively with MR imaging and PET findings and histological data for evaluating the clinical impact on the diagnostic yield and tumor resection.

RESULTS

The PET data influenced surgical decisions or procedures in all cases. The use of PET helped to better differentiate indolent from active components in complex lesions (in 12 patients); improved target selection and diagnostic yield of stereotactic biopsies without increasing the sampling; provided additional prognostic information; reduced the amount of tissue needed for biopsy sampling in brainstem lesions (in 20 cases); better delineated lesions that were poorly delineated on MR imaging and that infiltrated functional cortex (in 50 cases); significantly increased the amount of tumor tissue removed in cases in which total resection influenced survival (in 20 cases); guided resection in hypermetabolic areas (in 15 cases); improved early postoperative detection of residual tumor (in 20 cases); avoided unnecessary reoperation (in 5 cases); and supported the decision to undertake early second-look resection (in 8 cases).

CONCLUSIONS

The authors found that PET has a significant impact on the surgical decisions and procedures for managing pediatric brain tumors. Further studies may demonstrate whether PET improves outcomes in children.

Clinical interest of integrating positron emission tomography imaging in the workup of 55 children with incidentally diagnosed brain lesions

OBJECT

In this paper, the authors' goal was to evaluate the impact of PET data on the clinical management of incidental brain lesions in children.

METHODS

Between 1995 and 2007, 442 children with a newly diagnosed brain lesion were referred to the authors' department. Of these, 55 presented with an incidental brain lesion and were selected for study because MR imaging sequences revealed limitations in assessing the tumor, its evolving nature, and/or the malignant potential of the lesion diagnosed. Thirteen children were studied using FDG-PET and 42 with L-(methyl-(11)C)-methionine (MET)-PET; 3 children underwent both FDG-PET and MET-PET but only the MET-PET results were used in the analysis. The PET and MR images were combined in image fusion navigation planning. Drawing on their experience with PET in adults, the authors proposed the following treatment plans: 1) surgery in children with imaging evidence of increased PET tracer uptake, which is highly specific of tumor and/or malignant tumor tissue; or 2) conservative treatment in children in whom there was little or no tracer uptake on PET. The authors compared the PET data with the MR imaging-based diagnosis and either 1) the results of histological examination in surgically treated cases, or 2) the long-term outcome in untreated cases. They studied PET and MR imaging sensitivity and specificity in detecting tumor and malignant tissues, and evaluated whether PET data altered their clinical management.

RESULTS

Seventeen children had increased PET tracer uptake and underwent surgery. Tumor diagnosis was confirmed in all cases (that is, there were no false-positive findings). Cases in which there was little or no PET tracer uptake supported conservative treatment in 38 children. However, because PET was under evaluation, 16 of 38 lesions that were judged accessible for resection were surgically treated. Histological examination results demonstrated neither malignant nor evolving tumor tissue but yielded 9 indolent tumors (6 dysembryoplastic neuroectodermal tumors, 2 low-grade astrocytomas, and 1 low-grade astrocytoma and dysplasia) and 7 nontumoral lesions (3 cases of vasculitis, 3 of gliosis, and 1 of sarcoidosis). In 22 of the untreated 38 children, stable disease was noted during follow-up (range 18-136 months). Although an absence of PET tracer uptake might not exclude tumor tissue, PET did not reveal any false-negative findings in malignant or evolving tumor tissue detection in cases in which MR imaging showed false-positive and -negative cases in > 35 and 25% of the cases, respectively.

CONCLUSIONS

These data confirmed the high sensitivity and specificity of PET to detect tumor as well as malignant tissue. Regarding the treatment of the incidental brain lesions, the PET findings enabled the authors to make more appropriate decisions regarding treatment than those made on MR imaging findings alone. Therefore, the risk of surgically treating a nontumoral lesion was reduced as well as that for conservatively managing a malignant tumor. Nowadays, it is estimated that these data justify conservative management in incidental lesions with low or absent PET tracer uptake.

Hybrid imaging (SPECT/CT and PET/CT): improving therapeutic decisions

The incremental diagnostic value of integrated positron emission tomography-computed tomography (PET/CT) or single-photon emission computed tomography (SPECT)/CT images compared with PET or SPECT alone, or PET or SPECT correlated with a CT obtained at a different time includes the following: (1) improvement in lesion detection on both CT and PET or SPECT images, (2) improvement in the localization of foci of uptake resulting in better differentiation of physiological from pathologic uptake, (3) precise localization of the malignant foci, for example, in the skeleton vs soft tissue or liver vs adjacent bowel or node (4) characterization of serendipitous lesions, and (5) confirmation of small, subtle, or unusual lesions. The use of these techniques can occur at the time of initial diagnosis, in assessing the early response of disease to treatment, at the conclusion of treatment, and in continuing follow-up of patients. PET/CT and SPECT/CT fusion images affect the clinical management in a significant proportion of patients with a wide range of diseases by (1) guiding further procedures, (2) excluding the need of further procedures, (3) changing both inter- and intramodality therapy, including soon after treatment has been initiated, and (4) by providing prognostic information. PET/CT fusion images have the potential to provide important information to guide the biopsy of a mass to active regions of the tumor and to provide better maps than CT alone to modulate field and dose of radiation therapy. It is expected that the role of PET/CT and SPECT/CT in changing management will continue to evolve in the future and that these tools will be fundamental components of the truly "personalized medicine" we are striving to deliver.

Chronic traumatic encephalopathy in athletes: progressive tauopathy after repetitive head injury

Since the 1920s, it has been known that the repetitive brain trauma associated with boxing may produce a progressive neurological deterioration, originally termed dementia pugilistica, and more recently, chronic traumatic encephalopathy (CTE). We review 48 cases of neuropathologically verified CTE recorded in the literature and document the detailed findings of CTE in 3 profession althletes, 1 football player and 2 boxers. Clinically, CTE is associated with memory disturbances, behavioral and personality changes, parkinsonism, and speech and gait abnormalities. Neuropathologically, CTE is characterized by atrophy of the cerebral hemispheres, medial temporal lobe, thalamus, mammillary bodies, and brainstem, with ventricular dilatation and a fenestrated cavum septum pellucidum. Microscopically, there are extensive tau-immunoreactive neurofibrillary tangles, astrocytic tangles, and spindle-shaped and threadlike neurites throughout the brain. The neurofibrillary degeneration of CTE is distinguished from other tauopathies by preferential involvement of the superficial cortical layers, irregular patchy distribution in the frontal and temporal cortices, propensity for sulcal depths, prominent perivascular, periventricular, and subpial distribution, and marked accumulation of tau-immunoreactive astrocytes. Deposition of beta-amyloid, most commonly as diffuse plaques, occurs in fewer than half the cases. Chronic traumatic encephalopathy is a neuropathologically distinct slowly progressive tauopathy with a clear environmental etiology.

The value of positron emission tomography and proliferation index in predicting progression in low-grade astrocytomas of childhood

Astrocytomas are the most common brain tumors of childhood and adolescence. Low-grade astrocytomas (LGAs), in general, have favorable prognosis, but recurrence or progressive disease with dissemination, malignant transformation, and death occur in some cases. Current clinical and pathological measures including age, sex, imaging characteristics, location and size of the tumor, histopathology, and degree of resection cannot predict with certainty which tumors will demonstrate aggressive behavior. The objective of the study is to determine the predictive value of positron emission tomography (PET) and a proliferation index (PI) in identifying high risk LGAs. We reviewed 46 cases ages 5 months to 17 years with low-grade (WHO I-II) astrocytomas. All patients had PET scans utilizing [(18)F] fluorodeoxyglucose (FDG) and 24 cases had measurements with Ki-67/MIB-1 immunohistochemistry. Review of our data confirmed progressive disease (PD) in 18/46 (39%) of cases with 9/21 (42%) occurring after subtotal resection and 9/25 (36%) after gross total resection. The mortality rate was 5/46 (10.8%). Tumors with FDG hypermetabolism were significantly more likely to demonstrate aggressive behavior and PD. Increased PI values also suggested PD. Progression-free survival and time to progression were significantly longer for patients with hypometabolic scans. Time to progression was significantly longer with lower PI values. Results demonstrate that PET and PI are useful measures in the identification and stratification of high risk LGAs. The ability to identify a subset of progressive LGAs earlier may suggest the need for second-look neurosurgical procedures or more intensified adjuvant treatment that may ultimately improve outcome and survival.

Dosimetry of FDG PET/CT and other molecular imaging applications in pediatric patients

Effective doses for PET and SPECT imaging of molecular imaging agents depend on the radiopharmaceutical, administered activity and the weight of the patient. Effective doses for the accompanying CT scan depend on the CT protocol being used. CT protocols can be designed to produce diagnostic quality images, localization images or attenuation correction data without imaging. In each case, the co-registered molecular imaging examination (PET or SPECT) and the CT study must be acquired without patient movement. For PET/CT, attention to the respiratory phase during the CT study is also of critical importance. In addition to the molecular imaging agents (18)F-FDG and (123)I-MIBG that are frequently used in children, additional PET and SPECT imaging agents may have promise for molecular imaging in children.

Clinical Application of PET in Pediatric Brain Tumors

While rare in adults, central nervous system tumor is the most common solid tumor in childhood and is the leading cause of cancer death in children. Childhood brain tumors are different from those in adults in epidemiology, histologic features, and responses to treatment. Gliomas make up over one-half of all childhood brain tumors. Clinical application of PET imaging in brain tumors has demonstrated that it is helpful in tumor grading, establishing prognosis, defining targets for biopsy, and planning resection. This article emphasizes PET applications in childhood brain tumors, focusing on mainly gliomas with regard to tumor-grading and prognosis, distinguishing tumor recurrence from radiation necrosis, and PET guided diagnosis and treatment.

PET imaging in the surgical management of pediatric brain tumors

OBJECTIVE

The present article illustrates whether positron-emission tomography (PET) imaging may improve the surgical management of pediatric brain tumors (PBT) at different steps.

MATERIALS AND METHODS

Among 400 consecutive PBT treated between 1995 and 2005 at Erasme Hospital, Brussels, Belgium, we have studied with (18) F-2-fluoro-2-deoxy-D-glucose (FDG)-PET and/or L-(methyl-(11)C)methionine (MET)-PET and integrated PET images in the diagnostic workup of 126 selected cases. The selection criteria were mainly based on the lesion appearance on magnetic resonance (MR) sequences. Cases were selected when MR imaging showed limitations for (1) assessing the evolving nature of an incidental lesion (n = 54), (2) selecting targets for contributive and accurate biopsy (n = 32), and (3) delineating tumor tissue for maximal resection (n = 40). Whenever needed, PET images were integrated in the planning of image-guided surgical procedures (frame-based stereotactic biopsies (SB), frameless navigation-based resections, or leksell gamma knife radiosurgery).

RESULTS

Like in adults, PET imaging really helped the surgical management of the 126 children explored, which represented about 30% of all PBT, especially when the newly diagnosed brain lesion was (1) an incidental finding so that the choice between surgery and conservative MR follow-up was debated, and (2) so infiltrative or ill-defined on MR that the choice between biopsy and resection was hardly discussed. Integrating PET into the diagnostic workup of these two selected groups helped to (1) take a more appropriate decision in incidental lesions by detecting tumor/evolving tissue; (2) better understand complex cases by differentiating indolent and active components of the lesion; (3) improve target selection and diagnostic yield of stereotactic biopsies in gliomas; (4) illustrate the intratumoral histological heterogeneity in gliomas; (5) provide additional prognostic information; (6) reduce the number of trajectories in biopsies performed in eloquent areas such as the brainstem or the pineal region; (7) better delineate ill-defined PBT infiltrative along functional cortex than magnetic resonance imaging (MRI); (8) increase significantly, compared to using MRI alone, the number of total tumor resection and the amount of tumor tissue removed in PBT for which a total resection is a key-factor of survival; (9) target the resection on more active areas; (10) improve detection of tumor residues in the operative cavity at the early postoperative stage; (11) facilitate the decision of early second-look surgery for optimizing the radical resection; (12) improve the accuracy of the radiosurgical dosimetry planning.

CONCLUSIONS

PET imaging may improve the surgical management of PBT at the diagnostic, surgical, and post-operative steps. Integration of PET in the clinical workup of PBT inaugurates a new approach in which functional data can influence the therapeutic decision process. Although metabolic information from PET are valid and relevant for the clinical purposes, further studies are needed to assess whether PET-guidance may decrease surgical morbidity and increase children survival.