A review on investigation of the basic contrast mechanism underlying multidimensional diffusion MRI in assessment of neurological disorders.

INTRODUCTION: Multidimensional diffusion MRI (MDD MRI) is a novel diffusion technique that uses advanced gradient waveforms for microstructural tissue characterization to provide information about average rate, anisotropy and orientation of the diffusion and to disentangle the signal fraction from specific cell types i.e., elongated cells, isotropic cells and free water. AIM: To review the diagnostic potential of MDD MRI in the clinical setting for microstructural tissue characterization in patients with neurological disorders to aid in patient care and treatment. METHOD: A scoping review on the clinical applications of MDD MRI was conducted from original articles published in PubMed and Scopus from 2015 to 2021 using the keywords "Multidimensional diffusion MRI" OR "diffusion tensor distribution" OR "Tensor-Valued Diffusion" OR "b-tensor encoding" OR "microscopic diffusion anisotropy" OR "microscopic anisotropy" OR "microscopic fractional anisotropy" OR "double diffusion encoding" OR "triple diffusion encoding" OR "double pulsed field gradients" OR "double wave vector" OR "correlation tensor imaging" AND "brain" OR "axons". RESULTS: Initially 145 articles were screened and after applying inclusion and exclusion criteria, nine articles were included in the final analysis. In most of these studies, microscopic diffusion anisotropy within the lesion showed deviation from the normal-appearing tissue. CONCLUSION: Multidimensional diffusion MRI can provide better quantification and visualization of tissue microstructure than conventional diffusion MRI and can be used in the clinical setting for diagnosis of neurological disorders.

Demand for Essential Nonambulatory Neurosurgical Care Decreased While Acuity of Care Increased During the Coronavirus Disease 2019 (COVID-19) Surge.

BACKGROUND: In times of health resource reallocation, capacities must remain able to meet a continued demand for essential, nonambulatory neurosurgical acute care. This study sought to characterize the demand for and provision of neurosurgical acute care during the coronavirus disease 2019 (COVID-19) pandemic. METHODS: This single-center cross-sectional observational analysis compared nonambulatory neurosurgical consult encounters during the peri-surge period (March 9 to May 31, 2020) with those during an analogous period in 2019. Outcomes included consult volume, distribution of problem types, disease severity, and rate of acute operative intervention. RESULTS: A total of 1494 neurosurgical consults were analyzed. Amidst the pandemic surge, 583 consults were seen, which was 6.4 standard deviations below the mean among analogous 2016-2019 periods (mean 873; standard deviation 45, P = 0.001). Between 2019 and 2020, the proportion of degenerative spine consults decreased in favor of spinal trauma (25.6% vs. 34% and 51.9% vs. 41.4%, P = 0.088). Among aneurysmal subarachnoid hemorrhage cases, poor-grade (Hunt and Hess grades 4-5) presentations were more common (30% vs. 14.8%, P = 0.086). A greater proportion of pandemic era consults resulted in acute operative management, with an unchanged absolute frequency of acutely operative consults (123/583 [21.1%] vs. 120/911 [13.2%], P < 0.001). CONCLUSIONS: Neurosurgical consult volume during the pandemic surge hit a 5-year institutional low. Amidst vast reallocation of health care resources, demand for high-acuity nonambulatory neurosurgical care continued and proportionally increased for greater-acuity pathologies. In our continued current pandemic as well as any future situations of mass health resource reallocation, neurosurgical acute care capacities must be preserved.

Acute-onset binocular diplopia in neurological unit: Aetiological factors and diagnostic assessment.

OBJECTIVES: To investigate the aetiology of acute-onset binocular diplopia (AOBD) in neurological units and identify the key diagnostic procedures in this setting. MATERIALS AND METHODS: Clinico-demographic data from patients hospitalized for AOBD from 2008 to 2019 were retrospectively reviewed. AOBD due to an underlying neurological disorder known to cause diplopia was addressed as secondary diplopia. Ophthalmoparesis plus was defined when subtle neurological signs/symptoms other than ophthalmoparesis were detected during neurological examination. RESULTS: A total of 171 patients (mean age 57.6 years) were included in the study. A total of 89 subjects (52%) had an oculomotor disturbance consistent with sixth nerve palsy, and 42 (24.6%) showed multiple oculomotor nerve involvement. The most common cause of AOBD was presumed to be microvascular in 56 patients (32.7%), while a secondary aetiology was identified in 102 (59.6%). Ophthalmoparesis plus and multiple oculomotor nerve involvement significantly predicted a secondary aetiology in multivariable logistic regression analysis. Brain CT was never diagnostic in isolated ophthalmoparesis. A combination of neuroimaging examinations established AOBD diagnosis in 54.9% of subjects, whereas rachicentesis and neurophysiological examinations were found to be performant in the remaining cases. CONCLUSIONS: AOBD may herald insidious neurological disease, and an extensive diagnostic workup is often needed to establish a diagnosis. Neurological examination was pivotal in identifying patients at higher risk of secondary aetiology. Even in cases of apparently benign presentation, a serious underlying disease cannot be excluded. Brain MRI was found to perform well in all clinical scenarios, and it should be always considered when managing AOBD.

Neurological outcomes of congenital Zika syndrome in toddlers and preschoolers: a case series.

BACKGROUND: Congenital Zika syndrome causes a spectrum of neurological symptoms with varying effects on function that require different therapeutic strategies. To date, this spectrum of effects and its clinical implications have not been completely described. We describe the neurological examination findings in toddlers and preschoolers, including predominant symptom complexes and comorbidities. METHODS: This study is a case-series neurological evaluation of 75 children with congenital Zika syndrome in Campina Grande, Brazil. The study is part of a cohort of children with congenital Zika syndrome that started in 2015 and is still ongoing. Children with Zika virus infection detected during pregnancy (mothers exhibited rash and were followed and diagnosed by fetal ultrasound abnormalities or RT-PCR) or through microcephaly screening after birth, using Intergrowth 21 guidelines, were selected by laboratory and radiological criteria. Children were examined during a 10-day period in September, 2018, and underwent neurological interview, examination, and assessment of functional outcomes and comorbidities. Children were divided in groups of predominant corticospinal or neuromuscular clinical signs and the associations between these groups and clinical comorbidities were assessed. FINDINGS: All of the children recruited to the study from Nov 29, 2015 to Nov 30, 2017 had imaging correlates of congenital Zika syndrome. Children were assigned to groups depending on the signs exhibited, either corticospinal or neuromuscular, with or without dyskinetic signs. 75 children completed the evaluation, 38 (51%) girls and 37 (49%) boys. Median age was 33 months (range 26-40 months; IQR 29-34). Microcephaly was present at birth in 56 (75%) children, and 19 (25%) children were born with normal head circumference, 15 of whom later developed microcephaly. Neurological examination grouped four children as having isolated dyskinetic signs, 48 children were assigned to the corticospinal group and 23 into the neuromuscular group. Dyskinetic findings were present in 30 (40%) children, either alone (four [5%]) or combined with corticospinal (19 [40%] of 48) or neuromuscular (seven [30%] of 23) findings. Comorbidities were highly prevalent, and the neuromuscular group had worse functional outcomes, evaluated by gross motor function (p=0·026), manual abilities (p=0·0013), and communication function (p<0·0005) classification scales, than the corticospinal group, whereas pneumonia (p<0·0005) and urinary tract infections (p<0·0005) were more frequent in the corticospinal group. Cortical hyperexcitability was supported by several clinical correlates, such as early onset epilepsy, persistence of primitive reflexes, and dystonia. INTERPRETATION: We describe distinct neurological profiles in the congenital Zika syndrome spectrum, with functional outcomes tending to correlate with these groups. The clinical division of children based on the disease signs proposed here is supported by the literature on central and peripheral nervous system pathology in congenital Zika syndrome. The high prevalence of dyskinetic symptoms merits special attention. FUNDING: Brazilian National Council for Scientific and Technological Development and by the Coordination for the Improvement of Higher Education Personnel.

Neuropathologic Correlates of White Matter Hyperintensities in a Community-Based Cohort of Older Adults.

BACKGROUND: The association of white matter hyperintensities (WMH) with age-related vascular and neurodegenerative pathologies remains incompletely understood. OBJECTIVE: The objective of this work was to elucidate the neuropathologic correlates of WMH in a large community-based cohort of older adults. METHODS: Cerebral hemispheres from 603 community-based older adults were imaged with MRI ex vivo. All participants underwent annual clinical evaluation, cognitive assessment, and neuropathologic examination. WMH burden was assessed using a modified Fazekas rating scale. Multiple ordinal logistic regression was used to test the association of WMH burden with an array of age-related neuropathologies, adjusting for demographics. Mixed effects models of cognition controlling for neuropathologies and demographics were used to determine whether WMH burden contributes to cognitive decline beyond measured pathologies. RESULTS: WMH burden in the whole group was associated with both vascular and Alzheimer's disease (AD) pathologies: arteriolosclerosis (p < 10-4), gross (p < 10-4), and microscopic infarcts (p = 0.04), and amyloid-ß plaques (p = 0.028). In non-demented participants (mild or no cognitive impairment) (N = 332), WMH burden was related to gross infarcts (p = 10-4) and arteriolosclerosis (p < 10-4), but not to AD pathology. Similarly, in those with no cognitive impairment (N = 178), WMH burden was related to gross infarcts (p = 8×10-4) and arteriolosclerosis (p = 0.014). WMH burden was associated with faster decline in perceptual speed in both the whole (p = 0.038) and non-demented (p = 0.006) groups. CONCLUSION: WMH burden has independent associations with vascular pathologies in older adults regardless of clinical status, and with AD pathology later in the progression of AD. Moreover, WMH burden may reflect additional tissue injury not captured with traditional neuropathologic indices.

Imaging in neuro-ophthalmology in the context of value-based care.

PURPOSE OF REVIEW: Neuro-ophthalmic imaging is an invaluable tool for clinical decision-making and has evolved rapidly. At the same time, both imaging utilization and healthcare costs have skyrocketed, and concern for imaging overuse has become a salient topic. This article gives an overview of the current state of neuro-ophthalmic imaging from a value-based medicine lens and discusses recent neuro-ophthalmic advancements in OCT with these considerations in mind. RECENT FINDINGS: Neuro-ophthalmology is not immune to the waste prevalent in medical imaging. Recent guidelines recommend against routine imaging for ophthalmic conditions without the presence of symptoms. Although neuro-ophthalmic specialty consults and imaging compare favorably against other specialties, the diagnostic yield depending on imaging indication can vary dramatically. For newer developments such as in OCT, it is particularly difficult to assess cost-effectiveness despite the technology's exciting diagnostic potential. SUMMARY: Familiarity with guidelines to counter misuse, the diagnostic yield of imaging in particular situations, and the limitations of new technology can all help neuro-ophthalmologists make educated tradeoffs and adapt to the new landscape of cost-effective medicine. By helping to decrease costs and efficiently utilize limited resources, the end benefactors will be the increased number of patients who have greater access to affordable care.

Three-Dimensional Printing Role in Neurologic Disease.

Three-dimensional printing has evolved dramatically in recent years and is now available for clinical use. Technical operations of 2 of the most common rapid prototyping processes (stereolithography and fused deposition modeling) and the steps involved in the creation of a prototype are discussed. Current applications in human neurosurgery including presurgical planning and educational opportunities are reviewed before focusing on the current applications in veterinary neurology.

A framework for organ dose estimation in x-ray angiography and interventional radiology based on dose-related data in DICOM structured reports.

Although interventional x-ray angiography (XA) procedures involve relatively high radiation doses that can lead to deterministic tissue reactions in addition to stochastic effects, convenient and accurate estimation of absorbed organ doses has traditionally been out of reach. This has mainly been due to the absence of practical means to access dose-related data that describe the physical context of the numerous exposures during an XA procedure. The present work provides a comprehensive and general framework for the determination of absorbed organ dose, based on non-proprietary access to dose-related data by utilizing widely available DICOM radiation dose structured reports. The framework comprises a straightforward calculation workflow to determine the incident kerma and reconstruction of the geometrical relation between the projected x-ray beam and the patient's anatomy. The latter is difficult in practice, as the position of the patient on the table top is unknown. A novel patient-specific approach for reconstruction of the patient position on the table is presented. The proposed approach was evaluated for 150 patients by comparing the estimated position of the primary irradiated organs (the target organs) with their position in clinical DICOM images. The approach is shown to locate the target organ position with a mean (max) deviation of 1.3 (4.3), 1.8 (3.6) and 1.4 (2.9) cm for neurovascular, adult and paediatric cardiovascular procedures, respectively. To illustrate the utility of the framework for systematic and automated organ dose estimation in routine clinical practice, a prototype implementation of the framework with Monte Carlo simulations is included.

Percutaneous Lumbar Transfacet Screw Fixation: A Technique Analysis of 176 Screws in 83 Patients With Assessment of Radiographic Accuracy, Hardware Failure, and Complications.

BACKGROUND: Transfacet screw fixation can be used to supplement varying techniques of lumbar interbody fusion. The percutaneous placement of transfacet screws represents an alternative to pedicle screws for select cases, which can potentially minimize morbidity. OBJECTIVE: To analyze our experience with respect to accuracy, hardware failure, and neurologic compromise. METHODS: Clinical records gathered from August 2009 to January 2014 were retrospectively reviewed. We identified 83 patients who underwent placement of 176 consecutive percutaneous transfacet screws while in the prone or lateral position. Accuracy of screw placement was assessed on computed tomography (CT) by entry point and end point. Hardware failure was assessed by radiography or CT. Clinical complications were assessed during regular follow-up visits. RESULTS: Entry point accuracy was 91.4%. Seven cases of intra-articular screw placement and 1 para-articular screw placement were detected on CT. End-point accuracy was 82.8%. There were 16 cases of pedicle breach from 1 to 3 mm on CT. There were 2 screw fractures and 1 case of a Kirschner-wire fracture that were clinically inconsequential. One patient had new nondisabling leg numbness. One patient with new radicular leg pain required removal of a screw. CONCLUSION: The technique of percutaneous lumbar transfacet screw fixation can be performed accurately and safely with patients in the prone and lateral positions. Entry point inaccuracies were more common at rostral levels due to facet orientation. End-point inaccuracies (pedicle breaches) were more common in the intervertebral foramen where 2 clinical complications occurred.

[(18)F-FDG PET/CT in the evaluation of patients suspected of paraneoplastic neurological syndrome]. / PET/TC con (18)F-FDG en la valoración de pacientes con sospecha de síndrome paraneoplásico neurológico.

OBJECTIVE: This study aimed to determine the diagnostic impact of (18)F-FDG PET/CT based on the clinical features of paraneoplastic neurological syndrome (PNS). MATERIAL AND METHODS: Multicenter retrospective and longitudinal study of patients with suspicion of PNS. The clinical picture was classified into classic (CS) and non-classic syndrome (NCS). After the follow-up, the definitive or possible diagnosis of PNS was established. The pictures that did not match any of the previous criteria were categorized as non-classifiable. The state of the onco-neural antibodies was studied. The PET/CT was classified as positive or negative for the detection of malignancy. The relationship between PET/CT findings and the final diagnosis was determined. The differences between variables (Pearson test X(2)) and the relationship between the results of the PET/CT and the final diagnosis were analyzed. RESULTS: A total of 64 patients were analyzed, classifying 30% as CS and 42% as NCS. After the follow-up, 20% and 16% of subjects were diagnosed as possible and definitive PNS, respectively. Positive onco-neural antibodies were found in 13% of the patients. A definitive diagnosis of PNS was associated with a positive PET/CT (P=.08). A significant relation between antibodies expression and final diagnosis of neoplasia (P=.04) was demonstrated. The PET/CT correctly localized malignancy in 5/7 cases of invasive cancer. CONCLUSIONS: The PET/CT showed a higher percentage of positive results in patients with definitive diagnosis of PNS. Despite the low prevalence of malignancy in our series, the PET/CT detected malignancy in a significant proportion of patients with invasive cancer.

Deep impact of ultrasound in the intensive care unit: the "ICU-sound" protocol.

BACKGROUND: Ultrasound can influence the diagnosis and impact the treatment plan in critical patients. The aim of this study was to determine whether, without encountering major environment- or patient-related limitations, ultrasound examination under a critical care ultrasonography protocol can be performed to detect occult anomalies, to prompt urgent changes in therapy or induce further testing or interventions, and to confirm or modify diagnosis. METHODS: One hundred and twenty-five consecutive patients admitted to a general intensive care unit were assessed under a critical care ultrasonography protocol, and the data were analyzed prospectively. Systematic ultrasound examination of the optic nerve, thorax, heart, abdomen, and venous system was performed at the bedside. RESULTS: Environmental conditions hampered the examination slightly in 101/125 patients (80.8%), moderately in 20/125 patients (16%), and strongly in 4/125 patients (3.2%). Ultrasonographic findings modified the admitting diagnosis in 32/125 patients (25.6%), confirmed it in 73/125 patients (58.4%), were not effective in confirming or modifying it in 17/125 patients (13.6%), and missed it in 3/125 patients (2.4%). Ultrasonographic findings prompted further testing in 23/125 patients (18.4%), led to changes in medical therapy in 22/125 patients (17.6%), and to invasive procedures in 27/125 patients (21.6%). CONCLUSIONS: In this series of patients consecutively admitted to an intensive care unit, ultrasound examination revealed a high prevalence of unsuspected clinical abnormalities, with the highest number of new ultrasound abnormalities detected in patients with septic shock. As part of rapid global assessment of the patient on admission, our ultrasound protocol holds potential for improving healthcare quality.

The role of 4-D ultrasonography in prenatal assessment of fetal neurobehaviour and prediction of neurological outcome.

OBJECTIVE: To determine the role of 4-D ultrasonography in prenatal assessment of fetal neurobehavior and in prediction of adverse neurological outcome. DESIGN: Prospective cohort study. SETTING: Women Hospital, Hamad Medical Corporation, Qatar. POPULATION: Forty pregnant women between 20 and 38 weeks of gestation with high risk for neurological abnormalities and 40 low risk cases were included. METHODS: Prenatal fetal neurological assessment using Kurjak antenatal neurodevelopmental test (KANET). Postnatal neurological assessment was performed using Amiel-Tison's neurological assessment at term (ATNAT) for all live-borns. MAIN OUTCOME MEASURES: Prediction of fetuses at neurological risk. RESULTS: The difference in the range of KANET score was significant. A significant difference was shown for isolated head anteflexion, isolated eye blinking, facial expressions, mouth movements, isolated hand movements, hand to face movement, finger movements, and general movements. For isolated leg movement and cranial sutures, the difference was not significant. All cases with abnormal KANET proved to be abnormal postnatally. CONCLUSION: 4-D ultrasonography may have an important role in prenatal assessment of fetal neurobehavior and prediction of adverse neurological outcome. However, further large studies are recommended before the test could be recommended for wider clinical practice.

[Clinical application of computed tomography in cattle]. / Klinische Anwendung der Computertomographiebeim Rind.

Computed tomography involves the use of x-rays to produce cross-sectional images of body regions. It provides non-overlapping, two-dimensional images of all desired planes as well as three-dimensional reconstruction of regions of interest. There are few reports on the clinical use of computed tomography in farm animals. Its use in cattle is limited by high cost, the application of off-label drugs and the need for general anaesthesia. In cattle computed tomography is indicated primarily for diseases of the head, e.g. dental diseases and otitis media, and neurological disorders. Less often it is used for diseases of the vertebrae and limbs. In valuable cattle, the results of computed tomography can be an important part of preoperative planning or be used to avoid unnecessary surgery when the prognosis is poor.

The potential of 4D sonography in the assessment of fetal neurobehavior--multicentric study in high-risk pregnancies.

OBJECTIVE: An evolving challenge for obstetrician is to better define normal and abnormal fetal neurological function in utero in order to better predict antenatally which fetuses are at risk for adverse neurological outcome. PATIENTS AND METHODS: Prenatal neurological assessment in high-risk fetuses using four-dimensional ultrasound applying the recently developed Kurjak antenatal neurodevelopmental test (KANET). Postnatal neurological assessment was performed using Amiel Tison's neurological assessment at term (ATNAT) for all live-borns and general movement (GM) assessment for those with borderline and abnormal ATNAT. RESULTS: Inclusion criteria were met by 288 pregnant women in four centers of whom 266 gave birth to a live-born baby. It was revealed that 234 fetuses were neurologically normal, 7 abnormal and 25 borderline. Out of 7 abnormal fetuses ATNAT was borderline in 5 and abnormal in 2, whereas GM assessment was abnormal in 5 and definitely abnormal in 2. Out of 25 KANET borderline fetuses, ATNAT was normal in 7, borderline in 17 and abnormal in 1, whereas the GM assessment was as follows: normal optimal in 4, normal suboptimal in 20, and abnormal in 1. In summary, out of 32 borderline and abnormal fetuses ATNAT was normal in 7, borderline in 22 and abnormal in 3; GM assessment was normal optimal in 4, normal suboptimal in 20, abnormal in 6 and definitely abnormal in 2. CONCLUSION: The sonographic test requires further studies before being recommended for wider clinical practice.

The value of cerebral Doppler venous haemodynamics in the assessment of multiple sclerosis.

Iron stores in the white and deep grey matter in course of multiple sclerosis (MS) have never been explained and could be related to abnormalities in venous drainage, but this possibility has never before been investigated. From an initial cohort of 320 subjects, after application of exclusion criteria, we selected 109 patients affected by MS, and 177 controls respectively composed by age- and sex-matched, healthy aged, and patients affected by other neurological diseases. They blindly underwent transcranial and extracranial Color-Doppler sonographic examination (TCCS-ECD), aimed at investigating five parameters related to normal cerebral venous outflow haemodynamics. Overall we analyzed 1430 TCSS-ECD parameters. In controls we found 861 normal parameters of cerebral venous return vs. 24 anomalous, whereas in MS 288 parameters were normal and 257 anomalous, respectively. Consequently, each of the considered Doppler haemodynamic parameters, when compared to revised McDonald criteria as a gold standard of MS diagnosis, showed separately a highly significant sensitivity and a noteworthy specificity. However, the detection >or=2 parameters in the same subject, never observed in controls, perfectly overlapped the diagnosis of MS (value, 95%CI: sensitivity 100%, 97-100; specificity 100%, 98-100; positive predictive value 100%, 97-100, negative predictive value 100%, 98-100; p<0.0001). Moreover, this study demonstrates a significant impairment of cerebral venous drainage in patients affected by MS, a mechanism potentially related to increased iron stores.

Evidence-based imaging guidelines and Medicare payment policy.

OBJECTIVE: This study examines the relationship between evidence-based appropriateness criteria for neurologic imaging procedures and Medicare payment determinations. The primary research question is whether Medicare is more likely to pay for imaging procedures as the level of appropriateness increases. DATA SOURCES: The American College of Radiology Appropriateness Criteria (ACRAC) for neurological imaging, ICD-9-CM codes, CPT codes, and payment determinations by the Medicare Part B carrier for Florida and Connecticut. STUDY DESIGN: Cross-sectional study of appropriateness criteria and Medicare Part B payment policy for neurological imaging. In addition to descriptive and bivariate statistics, multivariate logistic regression on payment determination (yes or no) was performed. DATA COLLECTION METHODS: The American College of Radiology Appropriateness Criteria (ACRAC) documents specific to neurological imaging, ICD-9-CM codes, and CPT codes were used to create 2,510 medical condition/imaging procedure combinations, with associated appropriateness scores (coded as low/middle/high). PRINCIPAL FINDINGS: As the level of appropriateness increased, more medical condition/imaging procedure combinations were payable (low = 61 percent, middle = 70 percent, and high = 74 percent). Logistic regression indicated that the odds of a medical condition/imaging procedure combination with a middle level of appropriateness being payable was 48 percent higher than for an otherwise similar combination with a low appropriateness score (95 percent CI on odds ratio=1.19-1.84). The odds ratio for being payable between high and low levels of appropriateness was 2.25 (95 percent CI: 1.66-3.04). CONCLUSIONS: Medicare could improve its payment determinations by taking advantage of existing clinical guidelines, appropriateness criteria, and other authoritative resources for evidence-based practice. Such an approach would give providers a financial incentive that is aligned with best-practice medicine. In particular, Medicare should review and update its payment policies to reflect current information on the appropriateness of alternative imaging procedures for the same medical condition.

[Positron emission tomography with FDG and newly developed tracers for the assessment of brain metabolism and synaptic function in neurological disorders].

Positron emission tomography has enabled us to measure various fundamental parameters of human brain physiology and chemistry, such as cerebral blood flow, metabolism and synaptic functions. Blood flow and oxygen metabolism is important for the understanding of cerebro-vascular disease. Glucose metabolism is tightly coupled with brain function and FDG-PET is useful for the determination of epileptic foci and for the evaluation of tumor malignancy. Imaging analysis of functional neuroanatomy of these parameters is very promising for the early diagnosis of dementia, such as Alzheimer's disease. Measurement of pre- and post-synaptic function is applicable to the differential diagnosis of parkinsonism. In early stage of Parkinson's disease, only presynaptic dopaminergic function is impaired, while in multiple system atrophy with striato-nigral degeneration type, both pre-and post dopaminergic function is reduced. Development of new radiotracers is expected for detection of early specific pathological changes and more previous changes underlying the deterioration of neurochemistry, such as genetic abnormalities.

Use trends and geographic variation in neuroimaging: nationwide medicare data for 1993 and 1998.

BACKGROUND AND PURPOSE: Powerful tools, including CT and MR imaging, have revolutionized neuroimaging. These are routinely used, but the extent and variation of use has not been studied. Our purposes were to determine the use rates of MR imaging and CT (of spine, brain, or head and neck), myelography, conventional angiography, and MR angiography in diagnosing neurologic disorders; to study trends in use; and to determine regional variations in use. METHODS: We used the National Part B Medicare Database for 1993 and 1998 to compare rates of use for these procedures in 10 geographic regions. RESULTS: In 1993 and 1998, respectively, 13,897 and 19,431 (39.8% increase) neuroimaging procedures were performed per 100,000 Medicare beneficiaries nationwide. Use of brain or head and neck CT (30.4%) and MR imaging (43.6%), spinal CT (3.5%) and MR imaging (83.0%), myelography (56.6%), and conventional angiography (24.3%) increased in 1998 versus 1993. Increases in MR angiography were not assessed, because this procedure was not reimbursable in 1993. Regional use of brain or head and neck and spinal CT and MR studies varied considerably; ratios of highest and lowest rates were 1.38-1.56. Use of MR angiography, myelography, and conventional angiography varied three- to fourfold. CONCLUSION: Use of MR and CT studies of the brain or head and neck and of the spine increased considerably in the Medicare population between 1993 and 1998. Use of conventional invasive procedures such as myelography and angiography increased strikingly, contrary to the expected decline. Regional use varied substantially.