The particle size distribution of technegas and its influence on regional lung deposition

Jc, Strong; Je, Agnew

doi:10.1097/00006231-198906000-00008

Cited by 37 publications

(33 citation statements)

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“…This is in contrast to the earlier report by Busch et al [4] and supports the observations of Isawa et al [2] and Strong and Agnew [6]. As our PCS measurements show, TcG particles actually have an average size of 60-160 nm.…”

Section: Discussionsupporting

confidence: 89%

“…Thus, it was originally assumed that TcG might consist of such small "bucky Correspondence to: M. Lemb balls" [4] with a diameter of 5 nm or less. Size distribution measured with a screen diffusion battery, however, revealed an average diameter of about 140 nm [6]. This contradiction is clarified by the analysis of TcG particle structure and size distribution in the present study.…”

Section: Introductioncontrasting

confidence: 78%

See 1 more Smart Citation

Technegas: a study of particle structure, size and distribution

Lemb¹,

Oei²,

Eifert

et al. 1993

Eur J Nucl Med

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Technegas (TcG) was produced using a commercially available TcG generator. The structure and size distribution of TcG particles were examined by means of the following methods: (a) transmission electron microscopy (TEM), range: 1 nm-100 microns; (b) time-of-flight mass spectroscopy (MS), range: < 3 nm; (c) photon correlation spectroscopy (PCS), range: 3 nm-3 microns. The TEM images showed graphite particles (size 7-23 nm) agglomerated into larger secondary aggregates. The size of these aggregates, determined from PCS and TEM measurements, showed a log-normal distribution and typically ranged from 60 to 160 nm. No isolated particles smaller than 3 nm could be detected by MS. We conclude that TcG particles consist of technetium-99m labelled agglomerated graphite particles and have an average size of 97 nm (geometrice standard deviation (GSD): 1.55).

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Section: Discussionsupporting

confidence: 89%

Section: Introductioncontrasting

confidence: 78%

Technegas: a study of particle structure, size and distribution

Lemb¹,

Oei²,

Eifert

et al. 1993

Eur J Nucl Med

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“…Fifty percent of the radioactivity resides in particles smaller than the MMAD and 50% in larger particles. 17 The MMAD should preferably be smaller than 1.2 m. [18][19][20][21] It is not easy to define the aerodynamic properties of an aerosol. Hydrophilic particles may grow in size as the result of the humid environment of the airways.…”

Section: Aerosolsmentioning

confidence: 99%

Methodology for Ventilation/Perfusion SPECT

Bajc

Neilly

Miniati

et al. 2010

Seminars in Nuclear Medicine

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Ventilation/perfusion single-photon emission computed tomography (V/Q SPECT) is the scintigraphic technique of choice for the diagnosis of pulmonary embolism and many other disorders that affect lung function. Data from recent ventilation studies show that the theoretic advantages of Technegas over radiolabeled liquid aerosols are not restricted to the presence of obstructive lung disease. Radiolabeled macroaggregated human albumin is the imaging agent of choice for perfusion scintigraphy. An optimal combination of nuclide activities and acquisition times for ventilation and perfusion, collimators, and imaging matrix yields an adequate V/Q SPECT study in approximately 20 minutes of imaging time. The recommended protocol based on the patient remaining in an unchanged position during the initial ventilation study and the perfusion study allows presentation of matching ventilation and perfusion slices in all projections as well as in rotating volume images based upon maximum intensity projections. Probabilistic interpretation of V/Q SPECT should be replaced by a holistic interpretation strategy on the basis of all relevant information about the patient and all ventilation/perfusion patterns. PE is diagnosed when there is more than one subsegment showing a V/Q mismatch representing an anatomic lung unit. Apart from pulmonary embolism, other pathologies should be identified and reported, for example, obstructive disease, heart failure, and pneumonia. Pitfalls exist both with respect to imaging technique and scan interpretation. Semin Nucl Med 40: [415][416][417][418][419][420][421][422][423][424][425]

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“…More recently, substitution of 99m Tc by 68 Ga has been successfully demonstrated as a viable radioaerosol for PET (11,24), enabling combined PET V/Q imaging (25). Galligas, analogous to Technegas, is an aerosol comprising extremely small radiolabeled solid graphite particles that are deposited in the alveolar space, enabling ventilation imaging (26,27). In a piglet study (that included a control group) of induced lobar obstruction and methacholine-induced diffuse airway obstruction, Galligas demonstrated more detailed assessment of ventilation than did Technegas (24).…”

Section: Discussionmentioning

confidence: 99%

⁶⁸Ga PET/CT Ventilation–Perfusion Imaging for Pulmonary Embolism: A Pilot Study with Comparison to Conventional Scintigraphy

Hofman¹,

Beauregard²,

Barber³

et al. 2011

J Nucl Med

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Ventilation-perfusion (V/Q) scintigraphy is established for regional assessment of lung function in a variety of diseases, including pulmonary embolism (PE). PET/CT may further improve the accuracy and utility of V/Q imaging because of its superior technical characteristics. This pilot study assessed the feasibility of performing V/Q PET/CT and compared diagnostic utility with conventional V/Q imaging in patients with clinical suspicion of PE. Methods: Ten patients undergoing conventional V/Q imaging were prospectively recruited. PET/ CT V/Q imaging was performed after inhalation of 68 Ga-carbon nanoparticles ("Galligas") and administration of 68 Ga-macroaggregated albumin. Blinded to the results of the other study, SPECT/CT (n 5 9) or SPECT (n 5 1) images and PET/CT images were graded by a predefined scoring system for scan quality. The number of matched or unmatched defects and diagnosis were also measured and compared with a final diagnosis. Results: PET image quality was equivalent or superior to SPECT in all patients, with more homogeneous radiotracer distribution for both ventilation and perfusion studies (P , 0.01). Based on conventional V/Q imaging, the diagnosis was acute PE in 2 patients and no PE in 7 patients, and the imaging results were nondiagnostic in 1 patient. The PET/CT diagnosis was concordant in 8 patients, and these studies demonstrated a similar number and distribution of matched and unmatched defects. In 1 discordant case, a patient with a SPECT/CT study that was nondiagnostic because of severe airway disease showed no PE on PET/CT. In another, the diagnosis of PE established on SPECT/CT was not reported on PET/CT 2 d later, possibly because of interval clot lysis or migration. Conclusion: This intraindividual comparative study demonstrated that V/Q PET/CT with 68 Ga-labeled radiotracers can be performed in clinical practice. Compared with conventional V/Q imaging, advantages include higher-resolution, fully tomographic images with potentially better regional quantitation of lung function. The short half-life of 68 Ga also enables more flexible acquisition protocols with the option of performing ventilation studies selectively on patients with abnormal perfusion. On the basis of our results, further studies are indicated to assess whether V/Q PET/CT can improve diagnostic algorithms for patients with suspected PE. Vent ilation-perfusion (V/Q) scintigraphy allows assessment of regional lung function in a variety of diseases. Most studies are performed to assess patients with suspected pulmonary embolism (PE) because presenting symptoms and signs are variable and insufficient for a clinical diagnosis. The Prospective Investigation of Pulmonary Embolism Diagnosis study (1), designed in 1983, established V/Q imaging as the standard of care at the time. V/Q imaging has improved in the past 3 decades because of major advances in image acquisition, reconstruction, and analysis techniques. The use of 99m Tc-labeled carbon nanoparticles (Technegas; Cyclopharm) has improved the assessment of ventil...

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The particle size distribution of technegas and its influence on regional lung deposition

Cited by 37 publications

References 0 publications

Technegas: a study of particle structure, size and distribution

Technegas: a study of particle structure, size and distribution

Methodology for Ventilation/Perfusion SPECT

⁶⁸Ga PET/CT Ventilation–Perfusion Imaging for Pulmonary Embolism: A Pilot Study with Comparison to Conventional Scintigraphy

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The particle size distribution of technegas and its influence on regional lung deposition

Cited by 37 publications

References 0 publications

Technegas: a study of particle structure, size and distribution

Technegas: a study of particle structure, size and distribution

Methodology for Ventilation/Perfusion SPECT

68Ga PET/CT Ventilation–Perfusion Imaging for Pulmonary Embolism: A Pilot Study with Comparison to Conventional Scintigraphy

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Product

Resources

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⁶⁸Ga PET/CT Ventilation–Perfusion Imaging for Pulmonary Embolism: A Pilot Study with Comparison to Conventional Scintigraphy