Respiratory motion during Yttrium PET contributes to underestimation of tumor dose and overestimation of normal liver tissue dose.

Background Yttrium-90 dosimetry after radioembolization is reliant on accurate quantitative imaging of the microsphere deposition. Previous studies have focused on the correction of geometrical resolution effects. Purpose To uncover additional effects of respiratory motion.

Respiratory gated and prolonged acquisition 18F-FDG PET improve preoperative assessment of colorectal liver metastases.

Background: Detection of small liver metastases from colorectal cancer by 18F-FDG PET/CT is hampered by high physiologic uptake in the liver parenchyma and respiratory movements during image acquisition.

Purpose: To investigate whether two tailored 18F-FDG PET liver acquisitions (prolonged liver acquisition time [PL-PET] and repeated breath-hold respiratory gated liver acquisition [RGL-PET]) would improve detection of colorectal liver metastases, when added to a standard whole body PET (WB-PET).

Material And Methods: Twenty consecutive patients referred to our hospital for surgical treatment of colorectal liver metastases diagnosed with contrast-enhanced CT underwent preoperative 18F-FDG PET/CT tailored for detection of liver metastases.

Characterization of an asymmetric add-on collimator used with a hand-held gamma probe for radioguided surgery and sentinel node detection: a demonstration of an alternative collimation method.

Objective: The aim of the study was to investigate a new principle for collimation of gamma probes for radioguided surgery and sentinel node detection: the use of asymmetric lateral shielding. The intension was to maintain the sensitivity in the lateral and forward directions on the unshielded side while at the same time to shield the probe against high activity sources that could mask the signal from the object to be detected.

Methods: The device was constructed to shield only against photons that come from a region in space that spans approximately 180° sideways and forwards relative to the detector.

An implementation of time-efficient respiratory-gated PET acquisition by repeated breath-holds.

Background: Respiratory gating in positron emission tomography (PET) is used to improve detection of small tumors in the lower lung regions and in the liver, and to obtain a better estimate of the standardized uptake value (SUV).

Purpose: To develop a time-efficient method for acquisition of respiratory-gated PET/CT that would produce one single high quality image volume corresponding to a breath-hold state.

Material And Methods: An instrument was developed that displayed to the patient either red or green numbers, counting down from a chosen maximum to one at a rate of one dial per second.

Correction of partial volume effect in (18)F-FDG PET brain studies using coregistered MR volumes: voxel based analysis of tracer uptake in the white matter.

A voxel-based algorithm to correct for partial volume effect in PET brain volumes is presented. This method (named LoReAn) is based on MRI based segmentation of anatomical regions and accurate measurements of the effective point spread function of the PET imaging process. The objective is to correct for the spill-out of activity from high-uptake anatomical structures (e.

Quantitative dynamic ¹⁸FDG-PET and tracer kinetic analysis of soft tissue sarcomas.

Purpose: To study soft tissue sarcomas using dynamic positron emission tomography (PET) with the glucose analog tracer [(18)F]fluoro-2-deoxy-D-glucose ((18)FDG), to investigate correlations between derived PET image parameters and clinical characteristics, and to discuss implications of dynamic PET acquisition (D-PET).

Material And Methods: D-PET images of 11 patients with soft tissue sarcomas were analyzed voxel-by-voxel using a compartment tracer kinetic model providing estimates of transfer rates between the vascular, non-metabolized, and metabolized compartments. Furthermore, standard uptake values (SUVs) in the early (2 min p.

A gel tumour phantom for assessment of the accuracy of manual and automatic delineation of gross tumour volume from FDG-PET/CT.

Introduction: Our primary aim was to make a phantom for PET that could mimic a highly irregular tumour and provide true tumour contours. The secondary aim was to use the phantom to assess the accuracy of different methods for delineation of tumour volume from the PET images.

Material And Methods: An empty mould was produced on the basis of a contrast enhanced computed tomography (CT) study of a patient with a squamous cell carcinoma in the head and neck region.

Dynamic FDG PET for assessing early effects of cerebral hypoxia and resuscitation in new-born pigs.

Purpose: Changes in cerebral glucose metabolism may be an early prognostic indicator of perinatal hypoxic-ischaemic injury. In this study dynamic ¹⁸F-FDG PET was used to evaluate cerebral glucose metabolism in piglets after global perinatal hypoxia and the impact of the resuscitation strategy using room air or hyperoxia.

Methods: New-born piglets (n = 16) underwent 60 min of global hypoxia followed by 30 min of resuscitation with a fraction of inspired oxygen (FiO₂) of 0.

Nasal deposition and clearance in man: comparison of a bidirectional powder device and a traditional liquid spray pump.

Background: Delivery of powder formulations to the nose is an attractive alternative for many drugs and vaccines. This study compared the regional nasal deposition and clearance patterns of lactose powder delivered by the OptiNose powder device (Opt-Powder; OptiNose US Inc., Yardley, PA, USA) to that of liquid aerosol administered via a traditional hand-actuated liquid spray pump (Rexam SP270, Rexam Pharma, France).

Dynamic respiratory gated (18)FDG-PET of lung tumors - a feasibility study.

Background: (18)FDG-PET/CT imaging is well established for diagnosis and staging of lung tumors. However, more detailed information regarding the distribution of FDG within the tumor, also as a function of time after injection may be relevant. In this study we explore the feasibility of a combined dynamic and respiratory gated (DR) PET protocol.

Monitoring the effect of targeted therapies in a gastrointestinal stromal tumor xenograft using a clinical PET/CT.

Purpose: The purpose of this study is to assess treatment responses induced by the two tyrosine kinase inhibitors, Imatinib and Sunitinib, in a gastrointestinal stromal tumor (GIST) xenograft using a clinical positron emission tomography/computed tomography (PET/CT) scanner.

Methods: Nude mice bearing human GIST xenografts with mutations in exons 11 and 17 were randomly allocated to treatment with Imatinib, Sunitinib, or placebo daily for seven consecutive days. 2-deoxy-2-[(18)F]fluoro-D: -glucose PET ((18)F-FDG-PET/CT) was performed in a clinical PET/CT scanner at baseline (day 0) and 1 and 7 days after onset of treatment.

A method for on-site measurements of the effective spatial resolution in PET image volumes reconstructed with OSEM and Gaussian post-filters.

When PET image volumes are reconstructed with ordered subset expectation-maximization (OSEM) and subjected to filtration with a 3D Gaussian filter the effective spatial resolution is a function of both the intrinsic scanner resolution and the user-selectable spatial width of the filter. A method was developed to derive the effective spatial resolution from such volumes obtained after acquisitions with a line source on a Siemens Biograph 64 PET/CT scanner. Assuming Gaussian distributions, the full widths at half maximum (FWHM) were derived from probit plots of cumulative spatial distributions across the line source.

A new method for scintigraphic quantification of deposition and clearance in anatomical regions of the human nose.

Objectives: To develop methods for absolute quantification of the deposition of 99mTc-labeled aerosols and powders in well-defined anatomical regions of the nose, and to enable accurate comparisons of different nasal administration techniques in the same individual.

Methods: The volunteer was seated and positioned relative to the scintillation camera field of view by means of a fixation frame. After nasal administration, a dynamic series of images was acquired for 32 min with a lateral direction of view.

A simulation of MRI based dose calculations on the basis of radiotherapy planning CT images.

Background: The advantage of MRI-based radiotherapy planning is the superior soft tissue differentiation. However, for accurate patient dose calculations, a conversion of the MR images into Hounsfield CT maps is necessary. The aim of the present study was to investigate the dose accuracy that can be achieved with segmented MR-images derived from the planning CT images by assigning fixed densities to different classes of tissues.

Integrin scintimammography using a dedicated breast imaging, solid-state gamma-camera and (99m)Tc-labelled NC100692.

Objective: Integrin scintimammography with NC100692 and a dedicated gamma-camera, LumaGEM, based on semi-conductor technology, was performed to investigate the detection ability of this combination in breast cancer.

Methods: Eight patients with a high suspicion of breast cancer were administered 600-750 MBq (99m)Tc-labelled NC100629. Two acquisitions using a cranio-caudal and a lateral view were used, with moderate compression of the breast.

Early changes in apparent diffusion coefficient predict the quantitative antitumoral activity of capecitabine, oxaliplatin, and irradiation in HT29 xenografts in athymic nude mice.

Purpose: The purpose of this study was to evaluate the possible use of changes in apparent diffusion coefficient (ADC) measured by magnetic resonance imaging for pretreatment prediction and early detection of tumor response in a mouse model during fractionated chemoradiotherapy.

Materials And Methods: Athymic mice with bilateral HT29 xenografts on rear flanks were allocated into three groups: control, capecitabine, and capecitabine and oxaliplatin. The left flanks of the mice received daily irradiation.

Breath actuated device improves delivery to target sites beyond the nasal valve.

Objectives: The objective was to compare nasal deposition patterns achieved with a conventional hand actuated spray pump and a novel breath actuated bidirectional prototype device housing the same spray pump (OptiMist, OptiNose AS, Oslo, Norway).

Study Design And Methods: The bidirectional delivery device exploits the posterior connection between the nasal passages persisting when the velum automatically closes during oral exhalation. The deposition and clearance patterns achieved with the two devices were compared in nine healthy subjects by scintigraphy after administration of Tc-aerosols.

Localized internal radiotherapy with 90Y particles embedded in a new thermosetting alginate gel: a feasibility study in pigs.

Background: Internal radiotherapy requires the localization of the radionuclide to the site of action. A new injectable alginate gel formulation intended to undergo immediate gelation in tissues and capable of encapsulating radioactive particles containing 90Y was investigated.

Methods: The formulation was injected intramuscularly, into the bone marrow compartment of the femur and intravenously, respectively, in pigs.

Bi-directional nasal delivery of aerosols can prevent lung deposition.

Nasal delivery of drugs and vaccines has important advantages compared to injection and oral administration, and is being considered for a widening range of vaccines and substances with topical and systemic action. Traditional nasal delivery technologies are, however, trapped in the dilemma between achieving improved nasal distribution and limiting deposition in the lower airways. The novel bi-directional nasal delivery concept takes advantage of the posterior connection between the nasal passages persisting when the soft palate automatically closes during oral exhalation.

Effects of photon attenuation on the determination of cardiac volumes from reconstructed counts in gated blood pool SPET.

In gated cardiac blood pool single-photon emission tomography (SPET), the volume of a ventricle may be determined by a method that exploits the proportionality between that volume and the total reconstructed counts within a larger volume of interest that includes the actual ventricle. The present work was carried out to determine how the attenuation of photons modifies the reconstructed counts obtained with this technique, and how this affects the accuracy of volume determination. Furthermore, we wanted to investigate how count-based determination of ventricle volumes is affected by the total SPET rotation angle and by different arm positions.

Studies on the synthesis and biological properties of non-carrier-added [(125)I and (131)I]-labeled arylalkylidenebisphosphonates: potent bone-seekers for diagnosis and therapy of malignant osseous lesions.

Arylalkylidenebisphosphonates labeled with nca [(125)I or (131)I] have been synthesized and their biological function investigated. The label was attached to the aromatic group in high yield and under mild conditions by means of iododesilylation. The bone affinities of the radioactive compounds were investigated in normal Balb/C mice.

A method for measurement of the uptake patterns of two beta-emitting radionuclides in the same tissue section with a digital silicon detector: application to a study of 89SrCl2 and 153Sm-EDTMP in a dog with spontaneous osteosarcoma.

The biological effect of a radiopharmaceutical depends heavily on the heterogeneity of the uptake in the various tissues. A comparative study of two radiopharmaceuticals should therefore include a comparison of the uptake patterns in different tissues. To eliminate the problems caused by variation in kinetics and tumour characteristics between individuals, such a comparison should be based on measured distributions of the radiopharmaceuticals in the same tissue sample.