Attenuation Correction and Incomplete Projection in Single Photon Emission Computed Tomography

Chang, Lee-Tzuu

doi:10.1109/tns.1979.4330536

Cited by 86 publications

(23 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Image reconstruction was made by the filtered back projection using a Butterworth filter, 28 and attenuation correction was made numerically by assuming an elliptic object shape for each slice and a uniform attenuation coefficient (0.1/cm). 29,30 Correction for scattered photons was not applied. Image slices were arranged parallel to the cantho-meatal (CM) line and obtained at 8 mm intervals in the whole brain.…”

Section: Single Photon Emission Computed Tomography Scansmentioning

confidence: 99%

See 1 more Smart Citation

Changes in regional cerebral blood flow abnormalities in late‐life depression following response to electroconvulsive therapy

Awata

Konno

Kawashima

et al. 2002

Psychiatry Clin Neurosci

View full text Add to dashboard Cite

The impact of electroconvulsive therapy (ECT) on the regional cerebral blood flow (rCBF) abnormalities in late-life depression is still unknown and the clinical significance of these findings in late-life depression has not been fully discussed. Using single photon emission computed tomography (SPECT) with 99m Tc-hexamethylpropylene amine oxime ( 99m Tc-HMPAO), we examined the changes of rCBF patterns in nine late-life patients with major depressive episodes before and following response to ECT compared with nine age-and sex-matched healthy volunteers. Statistical comparisons were made on both region-of-interest (ROI) and voxel-by-voxel bases. In ROI-based analyses, a mean rCBF was significantly decreased in the patients before ECT compared with the control, significantly increased (normalized) in the patients 2 weeks after ECT compared with that before ECT, and still increased in the patients 12 weeks after ECT compared with that before ECT. In voxel-by-voxel analyses, a significant rCBF reduction was found in the bilateral pre-and subcallosal anterior cingulate cortex, the bilateral caudal orbitofrontal cortex, the right insular cortex and the right posterior middle frontal gyrus in patients before ECT compared with the control, and similar rCBF patterns were shown at 2 weeks and 12 weeks after ECT. We propose the hypothesis that a mean rCBF reduction may have a state-related property while persistent anterior paralimbic hypoperfusion may have a trait-like property, which relates to the relapse vulnerability as well as a tendency toward medication failure and illness chronicity in late-life depression.

show abstract

Section: Single Photon Emission Computed Tomography Scansmentioning

confidence: 99%

“…Relapse rate is 33%. Trazodone (75), Levomepromazine (30) multiple comparison of mean rCBF between the control, the patients before ECT, the patients 2 weeks after ECT and the patients 12 weeks after ECT. A significant mean rCBF reduction was found in the patients before ECT compared with the control (P < 0.01).…”

Section: Regional Cerebral Blood Flowmentioning

confidence: 99%

Changes in regional cerebral blood flow abnormalities in late‐life depression following response to electroconvulsive therapy

Awata

Konno

Kawashima

et al. 2002

Psychiatry Clin Neurosci

View full text Add to dashboard Cite

show abstract

“…2). Los datos fueron reconstruidos mediante método OSEM, realizando corrección de atenuación (método de Chang) (Chang, 1979) y análisis semi-cuantitativo de la perfusión cortical o flujo sanguíneo cortical "FSC" (método de Tanaka et al, 2000) aplicado a las cortezas frontal e insular, núcleos caudados y cuerpo amigdalino (Fig. 3).…”

Section: Materials Y Métodounclassified

Hallazgos Morfométricos y Funcionales Acerca de la Ínsula en Población VIH+ con Apatía

Tornese

Nabar²

2017

Int. J. Morphol.

View full text Add to dashboard Cite

NABAR, M. J. Hallazgos morfométricos y funcionales acerca de la ínsula en población VIH+ con apatía. Int. J. Morphol., 35(1):273-286, 2017. RESUMEN:La corteza insular es uno de los componentes de la zona paralímbica que presenta conexiones con áreas corticales y subcorticales. El estudio en personas viviendo con VIH (PVVIH), donde la apatía es frecuente, la implicó como modulador de respuesta emocional y ejecutiva. El objetivo es describir morfométricamente y funcionalmente la ínsula en relación con estructuras cerebrales corticales y subcorticales en PVVIH con apatía en comparación con controles y con PVVIH sin apatía, a fin de determinar su implicancia. Estudiamos 23 encéfalos de PVVIH de sexo masculino con apatía según evaluaciones neuropsiquiátricas. Se utilizó resonancia magnética (RM) con protocolo cognitivo para cuantificación y tomografía por emisión de fotón único (SPECT) para evaluar la perfusión cortical, aplicados a: cortezas frontales, insulares, núcleos caudados y cuerpos amigdalinos. Registramos reducción significativa morfométrica de la corteza del cíngulo anterior izquierdo, núcleo caudado ipsilateral y cortezas dorso-laterales en VIH+ con apatía; la ínsula anterior registró una reducción no significativa (p=0,4). En el análisis funcional se determinó hipoperfusión en las cortezas del cíngulo anterior izquierdo, insular anterior izquierda y en el caudado de forma asimétrica; con hipoperfusiones relativas en regiones del hemisferio derecho. La perfusión de la ínsula anterior izquierda fue correlativa con la del caudado ipsilateral y proporcional a la severidad en el test de apatía. Concluimos que en la cohorte evaluada de pacientes viviendo con VIH y apatía hallamos un significativo compromiso funcional de la corteza insular anterior, correlativo con la afectación funcional y morfométrica de los núcleos caudados. La implicancia de la corteza insular sugiere su participación en la psicopatología de la apatía, parámetro vinculado con el déficit de interés por las actividades e iniciativas.PALABRAS CLAVE: Ínsula; Apatía; VIH; RM; SPECT. INTRODUCCIÓNLa corteza insular es uno de los componentes de la zona paralímbica con un rol crucial en la percepción y modulación de la sensibilidad, sensorialidad e información vegetativa que incluye al dolor y la sensibilidad visceral.La ínsula yace profundamente en el trasfondo del surco lateral, entre la corteza sensitiva posterior y la corteza motora anterior, y consiste en un giro largo y 5 giros breves más anteriores. Sus regiones posterior y anterior (de giros breves) son divididas por la arteria cerebral media, la cual pasa a través de la superficie de esta corteza.La corteza de la ínsula recibe aferencias de la corteza somatosensorial, de la auditiva y de los núcleos talámicos anteriores; proyecta eferencias a la corteza motora y al ló-bulo temporal; pero sus conexiones bidireccionales son con muchas estructuras filogenéticamente nuevas como el opér-culo parietal, los núcleos basales y las cortezas del cíngulo y frontales medial y orbitaria.Se registró que l...

show abstract

“…Scatter correction was performed using the TEW method (12) (subwindow; Butterworth cutoff frequency, 0.07 cycles/cm). For cases using FBP reconstruction, attenuation correction (13,14) was performed using the iterative Chang method with a linear attenuation coefficient of 0.15 cm 21 . In the OSEM method, we performed embedded processing of an attenuation map (m-map) within the detection probability.…”

Section: Performance Index Criteriamentioning

confidence: 99%

A 3-Dimensional Mathematic Cylinder Phantom for the Evaluation of the Fundamental Performance of SPECT

Onishi

Motomura²,

Takahashi³

et al. 2010

Journal of Nuclear Medicine Technology

View full text Add to dashboard Cite

Degradation of SPECT images results from various physical factors. The primary aim of this study was the development of a digital phantom for use in the characterization of factors that contribute to image degradation in clinical SPECT studies. Methods: A 3-dimensional mathematic cylinder (3D-MAC) phantom was devised and developed. The phantom (200 mm in diameter and 200 mm long) comprised 3 imbedded stacks of five 30-mm-long cylinders (diameters, 4, 10, 20, 40, and 60 mm). In simulations, the 3 stacks and the background were assigned radioisotope concentrations and attenuation coefficients. SPECT projection datasets that included Compton scattering effects, photoelectric effects, and g-camera models were generated using the electron g-shower Monte Carlo simulation program. Collimator parameters, detector resolution, total photons acquired, number of projections acquired, and radius of rotation were varied in simulations. The projection data were formatted in Digital Imaging and Communications in Medicine (DICOM) and imported to and reconstructed using commercial reconstruction software on clinical SPECT workstations. Results: Using the 3D-MAC phantom, we validated that contrast depended on size of region of interest (ROI) and was overestimated when the ROI was small. The low-energy general-purpose collimator caused a greater partial-volume effect than did the low-energy high-resolution collimator, and contrast in the cold region was higher using the filtered backprojection algorithm than using the ordered-subset expectation maximization algorithm in the SPECT images. We used imported DICOM projection data and reconstructed these data using vendor software; in addition, we validated reconstructed images. Conclusion: The devised and developed 3D-MAC SPECT phantom is useful for the characterization of various physical factors, contrasts, partialvolume effects, reconstruction algorithms, and such, that contribute to image degradation in clinical SPECT studies.

show abstract

Attenuation Correction and Incomplete Projection in Single Photon Emission Computed Tomography

Cited by 86 publications

References 9 publications

Changes in regional cerebral blood flow abnormalities in late‐life depression following response to electroconvulsive therapy

Changes in regional cerebral blood flow abnormalities in late‐life depression following response to electroconvulsive therapy

Hallazgos Morfométricos y Funcionales Acerca de la Ínsula en Población VIH+ con Apatía

A 3-Dimensional Mathematic Cylinder Phantom for the Evaluation of the Fundamental Performance of SPECT

Contact Info

Product

Resources

About