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Positron detection for the intraoperative localisation of cancer deposits.

Piert M, Burian M, Meisetschläger G, Stein HJ, Ziegler S, Nährig J, Picchio M, Buck A, Siewert JR, Schwaiger M - Eur. J. Nucl. Med. Mol. Imaging (2007)

Bottom Line: A total of 17 patients (12 receiving preoperative [(18)F]FDG PET imaging) with various histologically proven malignancies were included.In one case of a hepatic metastasis, the T/B ratio of 1.34 was below expectations, since the preoperative [(18)F]FDG PET scan was positive.The methodology holds promise for further clinical testing.

View Article: PubMed Central - PubMed

Affiliation: Department of Nuclear Medicine, Technische Universität München, Ismaningerstrasse 22, 81675 Munich, Germany. mpiert@umich.edu

ABSTRACT

Purpose: The study investigated the feasibility of a positron-sensitive hand-held detector system for the intraoperative localisation of tumour deposits resulting from intravenous [(18)F]FDG administration.

Methods: A total of 17 patients (12 receiving preoperative [(18)F]FDG PET imaging) with various histologically proven malignancies were included. Radioactivity from tumours and surrounding normal tissue was measured on average 3 h after administration of 36-110 MBq [(18)F]FDG and the tumour-to-background (T/B) ratio was calculated. In addition, phantom studies were performed to evaluate the spatial resolution and sensitivity of the probe.

Results: All known targeted tumour sites were identified by the positron probe. T/B ratios were generally high, with a mean T/B ratio of 6.6, allowing easy identification of most tumour sites. In one case of a hepatic metastasis, the T/B ratio of 1.34 was below expectations, since the preoperative [(18)F]FDG PET scan was positive. The probe was instrumental in the localisation of three additional tumour lesions (two lymph nodes, one anastomotic ring) that were not immediately apparent at surgery. Phantom studies revealed that [(18)F]FDG-containing gel (simulating tumour tissue), having 10 times more [(18)F]FDG than surrounding "normal" background gel, was clearly detectable in quantities as low as 15 mg. As measured in two cases, the absorbed radiation doses ranged from 2.5 to 8.6 microSv/h for the surgical team to 0.8 microSv/h for the aesthetician.

Conclusion: [(18)F]FDG-accumulating tumour tissues can be localised with positron probes intraoperatively with a low radiation burden to the patient and medical personnel. The methodology holds promise for further clinical testing.

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Related in: MedlinePlus

Sensitivity testing of the positron probe revealed approximately 250 counts per second (cps) recovered from a point source of 1 kBq of [18F]FDG
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Fig3: Sensitivity testing of the positron probe revealed approximately 250 counts per second (cps) recovered from a point source of 1 kBq of [18F]FDG

Mentions: The sensitivity of the beta probe for fluorine-18 positron detection was measured as 0.25 cps per Bq (250 cps per kBq) at a distance of 1 mm from a point source without cover (Fig. 3). Positron sensitivity decreased on average by 33% using the intraoperative 60-μm-thick latex cover. The probe’s sensitivity to penetrating 511-keV photons was tested by shielding the probe’s tip with a 1-mm-thick lead cover and found to be negligible (less than 1.5% of total counts at any count rate up to 1,000 cps) (Fig. 4). At a distance of 10 mm to the point source, the sensitivity for positrons decreased by a factor of 5, while the ratio between true positron detection and background detection from penetrating photons increased slightly to 3.5% of total counts.Fig. 3


Positron detection for the intraoperative localisation of cancer deposits.

Piert M, Burian M, Meisetschläger G, Stein HJ, Ziegler S, Nährig J, Picchio M, Buck A, Siewert JR, Schwaiger M - Eur. J. Nucl. Med. Mol. Imaging (2007)

Sensitivity testing of the positron probe revealed approximately 250 counts per second (cps) recovered from a point source of 1 kBq of [18F]FDG
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2562440&req=5

Fig3: Sensitivity testing of the positron probe revealed approximately 250 counts per second (cps) recovered from a point source of 1 kBq of [18F]FDG
Mentions: The sensitivity of the beta probe for fluorine-18 positron detection was measured as 0.25 cps per Bq (250 cps per kBq) at a distance of 1 mm from a point source without cover (Fig. 3). Positron sensitivity decreased on average by 33% using the intraoperative 60-μm-thick latex cover. The probe’s sensitivity to penetrating 511-keV photons was tested by shielding the probe’s tip with a 1-mm-thick lead cover and found to be negligible (less than 1.5% of total counts at any count rate up to 1,000 cps) (Fig. 4). At a distance of 10 mm to the point source, the sensitivity for positrons decreased by a factor of 5, while the ratio between true positron detection and background detection from penetrating photons increased slightly to 3.5% of total counts.Fig. 3

Bottom Line: A total of 17 patients (12 receiving preoperative [(18)F]FDG PET imaging) with various histologically proven malignancies were included.In one case of a hepatic metastasis, the T/B ratio of 1.34 was below expectations, since the preoperative [(18)F]FDG PET scan was positive.The methodology holds promise for further clinical testing.

View Article: PubMed Central - PubMed

Affiliation: Department of Nuclear Medicine, Technische Universität München, Ismaningerstrasse 22, 81675 Munich, Germany. mpiert@umich.edu

ABSTRACT

Purpose: The study investigated the feasibility of a positron-sensitive hand-held detector system for the intraoperative localisation of tumour deposits resulting from intravenous [(18)F]FDG administration.

Methods: A total of 17 patients (12 receiving preoperative [(18)F]FDG PET imaging) with various histologically proven malignancies were included. Radioactivity from tumours and surrounding normal tissue was measured on average 3 h after administration of 36-110 MBq [(18)F]FDG and the tumour-to-background (T/B) ratio was calculated. In addition, phantom studies were performed to evaluate the spatial resolution and sensitivity of the probe.

Results: All known targeted tumour sites were identified by the positron probe. T/B ratios were generally high, with a mean T/B ratio of 6.6, allowing easy identification of most tumour sites. In one case of a hepatic metastasis, the T/B ratio of 1.34 was below expectations, since the preoperative [(18)F]FDG PET scan was positive. The probe was instrumental in the localisation of three additional tumour lesions (two lymph nodes, one anastomotic ring) that were not immediately apparent at surgery. Phantom studies revealed that [(18)F]FDG-containing gel (simulating tumour tissue), having 10 times more [(18)F]FDG than surrounding "normal" background gel, was clearly detectable in quantities as low as 15 mg. As measured in two cases, the absorbed radiation doses ranged from 2.5 to 8.6 microSv/h for the surgical team to 0.8 microSv/h for the aesthetician.

Conclusion: [(18)F]FDG-accumulating tumour tissues can be localised with positron probes intraoperatively with a low radiation burden to the patient and medical personnel. The methodology holds promise for further clinical testing.

Show MeSH
Related in: MedlinePlus