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Zhou J, Leja AG, Salvatori M, Latta DD, Di Fulvio A. Application of Monte Carlo Algorithms to Cardiac Imaging Reconstruction. Curr Pharm Des 2021; 27:1960-1972. [PMID: 33371829 DOI: 10.2174/1381612826999201228215225] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 11/07/2020] [Indexed: 11/22/2022]
Abstract
Monte Carlo algorithms have a growing impact on nuclear medicine reconstruction processes. One of the main limitations of myocardial perfusion imaging (MPI) is the effective mitigation of the scattering component, which is particularly challenging in Single Photon Emission Computed Tomography (SPECT). In SPECT, no timing information can be retrieved to locate the primary source photons. Monte Carlo methods allow an event-by-event simulation of the scattering kinematics, which can be incorporated into a model of the imaging system response. This approach was adopted in the late Nineties by several authors, and recently took advantage of the increased computational power made available by high-performance CPUs and GPUs. These recent developments enable a fast image reconstruction with improved image quality, compared to deterministic approaches. Deterministic approaches are based on energy-windowing of the detector response, and on the cumulative estimate and subtraction of the scattering component. In this paper, we review the main strategies and algorithms to correct the scattering effect in SPECT and focus on Monte Carlo developments, which nowadays allow the threedimensional reconstruction of SPECT cardiac images in a few seconds.
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Affiliation(s)
- J Zhou
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, United States
| | - A G Leja
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, United States
| | - M Salvatori
- Fondazione Toscana G. Monasterio, Massa, MS 54100, Italy
| | - D Della Latta
- Fondazione Toscana G. Monasterio, Massa, MS 54100, Italy
| | - A Di Fulvio
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, United States
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Gulati A, Hier DB, Trepashko DW, Hughes JR. Superiority of Functional over Structural Neuroimaging in the Diagnosis of Primary Progressive Aphasia. J Neuroimaging 2016. [DOI: 10.1111/jon199332141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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3
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Perneczky R, Diehl-Schmid J, Pohl C, Drzezga A, Kurz A. Non-fluent progressive aphasia: cerebral metabolic patterns and brain reserve. Brain Res 2006; 1133:178-85. [PMID: 17184752 DOI: 10.1016/j.brainres.2006.11.054] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Revised: 11/15/2006] [Accepted: 11/16/2006] [Indexed: 01/18/2023]
Abstract
Functional imaging studies suggest that brain reserve allows patients with Alzheimer's disease with more years of schooling to cope better with brain damage. No studies exist on patients with non-fluent progressive aphasia (NFPA). We aimed to explore metabolic patterns of patients with NFPA and to provide evidence for brain reserve in NFPA. 11 right-handed patients with NFPA and 16 age-matched controls underwent (18)F-FDG PET imaging. Scans of patients and controls were compared in SPM2. A linear regression analysis with glucose metabolism as dependent variable and years of schooling as the independent variable, adjusted for age, gender, and a total score of the CERAD neuropsychological battery was conducted. The NFPA group showed a hypometabolism of the left hemisphere including the middle frontal, and inferior temporal and angular gyri, and the bilateral caudate nuclei and thalami (p(corr)<0.05). The regression analysis revealed a significant inverse association between education and glucose metabolism in the left inferior temporal, parahippocampal, and supramarginal gyri (p(corr)<0.05). We conclude that brain reserve is also present in NFPA.
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Affiliation(s)
- Robert Perneczky
- Departments of Psychiatry and Psychotherapy, Technische Universität München, Germany
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4
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Rogalski E, Blum D, Rademaker A, Weintraub S. False recognition of incidentally learned pictures and words in primary progressive aphasia. Neuropsychologia 2006; 45:368-77. [PMID: 16905162 PMCID: PMC2891448 DOI: 10.1016/j.neuropsychologia.2006.06.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 05/16/2006] [Accepted: 06/01/2006] [Indexed: 11/23/2022]
Abstract
Recognition memory was tested in patients with primary progressive aphasia (PPA), a language based dementia with relative preservation of memory for at least the first 2 years. The goal of the study was two-fold: (1) to compare true and false recognition rates for words versus pictures in patients with PPA and cognitively intact controls and (2) to determine if the semantic relatedness of distracters-to-targets influences recognition memory performance. Overall, performance of PPA patients was worse for words than pictures. PPA patients and healthy elderly controls showed similar recognition rates for studied items. However, the patients had significantly more false alarms than controls, particularly to semantically related items. This suggests that the aphasia in PPA patients contributes to their difficulty in selecting among items within a semantic class.
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Affiliation(s)
- Emily Rogalski
- Cognitive Neurology and Alzheimer's Disease Center, Northwestern University, Chicago, IL, USA.
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Tree JJ, Kay J, Perfect TJ. “Deep” language disorders in nonfluent progressive Aphasia: an evaluation of the “summation” account of semantic errors across language production tasks. Cogn Neuropsychol 2005; 22:643-59. [DOI: 10.1080/02643290442000220] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Catani M, Piccirilli M, Cherubini A, Tarducci R, Sciarma T, Gobbi G, Pelliccioli G, Petrillo SM, Senin U, Mecocci P. Axonal injury within language network in primary progressive aphasia. Ann Neurol 2003; 53:242-7. [PMID: 12557292 DOI: 10.1002/ana.10445] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Primary progressive aphasia (PPA) is characterized by an isolated progressive impairment of word use and comprehension reflecting the distribution of pathological processes within the left hemisphere. We used proton magnetic resonance spectroscopy (1H-MRS) to study in vivo the integrity of axonal fibers connecting perisylvian language areas in 11 patients with PPA, 11 subjects with Alzheimer's disease, and 22 controls. Brain metabolites (N-acetylaspartate, myoinositol, choline, creatine) were measured bilaterally within a volume of interest located in the central portion of the superior longitudinal fasciculus, a long associative bundle connecting Broca's area with Wernicke's area, and other language regions of the temporal lobe. In the PPA group, there was an asymmetrical N-acetylaspartate to creatine ratio reduction compared with Alzheimer's disease and controls, with greater changes on the left side. The myoinositol to creatine ratio was increased in the PPA group bilaterally compared with controls. The choline to creatine ratio did not differ among the three groups. These results indicate an asymmetrical focal axonal injury within the language network in PPA. The marked difference in the distribution of N-acetylaspartate to creatine between PPA and Alzheimer's disease suggests that proton magnetic resonance spectroscopy may help to differentiate between these two conditions.
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Affiliation(s)
- Marco Catani
- Institute of Psychiatry, London, United Kingdom.
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Newberg AB, Mozley PD, Sadek AH, Grossman M, Alavi A. Regional cerebral distribution of [Tc-99m] hexylmethylpropylene amineoxine in patients with progressive aphasia. J Neuroimaging 2000; 10:162-8. [PMID: 10918743 DOI: 10.1111/jon2000103162] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Progressive aphasia is a prominent clinical feature of several neurodegenerative disorders. This study used hexylmethylpropylene amineoxine (HMPAO) single photon emission computed tomography (SPECT) to estimate blood flow in areas of the brain that mediate language in patients with progressive aphasia and matched control subjects. The patient population consisted of four men and 12 women with a mean +/- SD age of 69.1 +/- 7.6. Of these, eight were classified as having a nonfluent form of aphasia, whereas the other eight had a fluent form. The patients were compared to 16 healthy volunteers who were studied with an identical protocol. The SPECT images of the brain were acquired with 740 MBq (20 mCi) of Tc-99m-labeled HMPAO on a triple-headed gamma camera equipped with fan beam collimators. The images were analyzed with a set of standardized templates. Mean counts per pixel in 33 regions of interest were compared to the mean counts in the whole supratentorial brain. A laterality index was determined for homotopic regions using the equation 100 x (R - L)/(1/2 x (R - L)). Patients with progressive aphasia had several regions of significantly decreased HMPAO uptake in the left cortex when compared to the homotopic regions on the right. The most prominent deficit in the nonfluent group, as determined by the laterality index, were found in the left dorsolateral prefrontal region (p < 0.05), whereas the most prominent deficits in the group with fluent aphasia were found in the left temporal and parietal language centers (p < 0.05). The left subcortical nuclei were differentially affected, particularly in patients with nonfluent aphasia. The HMPAO SPECT indicates that multiple regions of the left hemisphere are dysfunctional in patients with progressive aphasia. The pattern of perfusion deficits in patients with fluent aphasia appears to be distinct from the pattern in patients with nonfluent aphasia.
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Affiliation(s)
- A B Newberg
- Division of Nuclear Medicine, University of Pennsylvania Medical Center, Philadelphia, USA
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Zakzanis KK. The neuropsychological signature of primary progressive aphasia. BRAIN AND LANGUAGE 1999; 70:70-85. [PMID: 10534372 DOI: 10.1006/brln.1999.2140] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
An effect size analysis incorporating meta-analytic principles was used to review neuropsychological findings in patients with primary progressive aphasia (PPA). Studies dating back to 1982 were gathered and the neuropsychological test results from a total of 55 patients with PPA and 162 healthy controls were synthesized using effect size analyses. The results indicate that patients with PPA are most deficient on tests of verbal skill, followed by performance on measures of delayed recall, cognitive flexibility and abstraction, memory acquisition, attention/concentration, and, finally, performance skill. A rank-order list of specific neuropsychological tasks and test variables in order of sensitivity to PPA is also provided to aid in the interpretation of the quantitative results and in the differentiation of PPA from other disorders with prominent features of dementia such as Alzheimer's disease.
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Affiliation(s)
- K K Zakzanis
- Department of Psychology, University of Toronto, Toronto, Canada.
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Abstract
We report a 69-year-old male patient whose motor aphasia started at the age of 61. The language disability remained isolated and progressed over a period of eight years without any additional cognitive deficits. Computed tomography (CT) and magnetic resonance imaging (MRI) showed moderate cortical atrophy with frontal dominance. Single photon emission tomography (SPECT) showed hypoperfusion in the frontotemporoparietal region, positron emission tomography (PET) demonstrated a global cortical reduction of glucose utilization with a lesser decrement in the occipital lobes. The clinical symptoms and the neuropsychological findings fit the diagnosis of primary progressive aphasia.
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Affiliation(s)
- T G Nagy
- Department of Neurology, Semmelweis Medical University, Budapest, Hungary
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Croot K, Patterson K, Hodges JR. Single word production in nonfluent progressive aphasia. BRAIN AND LANGUAGE 1998; 61:226-273. [PMID: 9468772 DOI: 10.1006/brln.1997.1852] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We present an experiment investigation of the spoken single word production of two patients with nonfluent progressive aphasia. In Experiment 1, a task effect (reading > repetition > naming) suggested that phonological information available from task stimuli facilitated the patients' speech production; a length effect reflected the increased difficulty of phonological processing required for long words compared with that required for shorter words. Experiment 2 compared repetition, reading, copying, and writing to dictation tasks and demonstrated that a correspondence between input and output modality also facilitated performance. Experiment 3 showed that the patients' access to appropriate phonology in reading was positively related to the degree of correlation between orthographic and phonological forms. These results are discussed with reference to an account of pathologically weakened connections between nodes in an interactive spreading activation model of speech production of the type described by Dell (1986).
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Affiliation(s)
- K Croot
- MRC Applied Psychology Unit, Cambridge, United Kingdom
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Abstract
Primary progressive aphasia (PPA) was first recognized by Mesulam in 1982. Although dozens of cases have since been described, it has been difficult to place these cases into a coherent framework due to the wide variation in measures which have been reported. We review 170 contacts with 112 patients to provide a clinical, neuroanatomical, and neuropsychological profile of patients with the disorder. The progression of the disease is analyzed over a 10-year reporting period starting from symptom onset to show how progression affects five general linguistic skills: oral and written naming, reading, repetition, and general comprehension. The pattern of functional and neurological deficits in PPA is heterogeneous. Differences in the distribution of neurological anomalies between patients with bilateral and unilateral changes suggest that there may be two separate disease processes involved.
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Affiliation(s)
- C Westbury
- Department of Neuropsychology, Montreal Neurological Institute, Quebec, Canada
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Watt S, Jokel R, Behrmann M. Surface dyslexia in nonfluent progressive aphasia. BRAIN AND LANGUAGE 1997; 56:211-233. [PMID: 9027371 DOI: 10.1006/brln.1997.1742] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This article presents the case of a 59-year-old male, JH, with a 6-year history of primary progressive aphasia (PPA), a disorder characterized by isolated language deterioration with relative preservation of other cognitive abilities. JH also shows typical features of surface dyslexia, a reading disorder exemplified by the selective preservation of phonological reading. One recent theory is that surface dyslexia in individuals with PPA results from a loss of semantic knowledge. In this paper we consider an additional possibility and present data supporting the notion that surface dyslexia may also arise from the malfunction in the links between semantic representations and phonology. JH has remarkably preserved lexical semantic knowledge when assessed on tasks that do not require verbal output. Further, item-by-item comparisons of his oral reading and comprehension ability show no significant correspondence between his reading and semantic knowledge. These findings lead us to conclude that, in JH's case, the surface dyslexia is attributable not to a semantic deficit per se but rather to the inability to access phonological information from semantics. JH's language profile is considered in relation to potential sources of surface dyslexia and other cases of progressive aphasia.
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Affiliation(s)
- S Watt
- Rotman Research Institute, Baycrest Centre for Geriatric Care, Toronto, Canada.
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Broussolle E, Bakchine S, Tommasi M, Laurent B, Bazin B, Cinotti L, Cohen L, Chazot G. Slowly progressive anarthria with late anterior opercular syndrome: a variant form of frontal cortical atrophy syndromes. J Neurol Sci 1996; 144:44-58. [PMID: 8994103 DOI: 10.1016/s0022-510x(96)00096-2] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We describe eight patients with slowly progressive speech production deficit combining speech apraxia, dysarthria, dysprosody and orofacial apraxia, and initially no other deficit in other language and non-language neuropsychological domains. Long-term follow-up (6-10 years) in 4 cases showed an evolution to muteness, bilateral suprabulbar paresis with automatic-voluntary dissociation and frontal lobe cognitive slowing without generalised intellectual deterioration. Most disabled patients presented with an anterior opercular syndrome (Foix-Chavany-Marie syndrome), and pyramidal or extrapyramidal signs. CT and MRI findings disclosed asymmetric (left > right) progressive cortical atrophy of the frontal lobes predominating in the posterior inferior frontal region, notably the operculum. SPECT and PET revealed a decreased cerebral blood flow and metabolism, prominent in the left posterior-inferior frontal gyrus and premotor cortex, extending bilaterally in the most advanced cases. Pathological study of two cases showed non-specific neuronal loss, gliosis, and spongiosis of superficial cortical layers, mainly confined to the frontal lobes, with no significant abnormalities in the basal ganglia, thalamus, cerebellum, brain stem (except severe neuronal loss in the substantia nigra in one case), and spinal cord. We propose to call this peculiar syndrome Slowly Progressive Anarthria (SPA), based on its specific clinical presentation, and its metabolic and pathological correlates. SPA represents another clinical expression of focal cortical degeneration syndromes, that may overlap with other similar syndromes, specially primary progressive aphasia and the various frontal lobe dementias.
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Affiliation(s)
- E Broussolle
- Service de Neurologie, Hôpital Neurologique, Lyon, France
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Clinical expression and diagnosis of atypical cortical degenerative syndromes. J Clin Psychol Med Settings 1995; 2:275-88. [PMID: 24226198 DOI: 10.1007/bf01990882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Atypical cortical degenerative syndromes of the non-Alzheimer's disease type are becoming increasingly recognized in the literature. Three cases consisting of primary progressive aphasia, posterior cortical atrophy, and frontal lobe dementia of the non-Alzheimer's type are presented to replicate and extend emerging literature. Detailed clinical description and neuropsychological data, coupled with confirmatory neurofunctional imaging, are presented to provide empirical support that specific inclusion and exclusion criteria can be applied to clinically diagnosis atypical degenerative cortical dementias.
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Primary Progressive Aphasia: Sharpening the Focus on a Clinical Syndrome. RESEARCH AND PERSPECTIVES IN ALZHEIMER’S DISEASE 1992. [DOI: 10.1007/978-3-642-46776-9_6] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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