We examined the hypothesis that recording multiple elastic pressure-volume (Pel/V) curves and calculating alveolar derecruitment (V(DER)) induced by decreasing positive end-expiratory pressure (PEEP) ...may allow determination of alveolar closing pressures, thus helping to select the optimal PEEP level. V(DER) measured in 16 patients with acute lung injury (ALI) was compared with the lower inflection point (LIP) and oxygenation changes. A modified automated method was used to record multiple Pel/V curves at low constant flow. PEEP was decreased in 5-cm H(2)O steps, from 20 or 15 cm H(2)O to 0 cm H(2)O (ZEEP). V(DER) was the volume loss between the curves recorded from PEEP and from ZEEP at the same Pel. Derecruitment occurred at each PEEP decrement, being spread almost uniformly over the 20/15 to 0 cm H(2)O range. V(DER) was not correlated with LIP. V(DER) changes correlated with Pa(O(2))/FI(O(2)) changes (rho = 0.6, p = 0.02). Linear compliance at ZEEP was correlated to V(DER) at PEEP 15 cm H(2)O (rho = 0.9, p = 0.001), suggesting that compliance above LIP may reflect the amount of recruitable lung. Thus, alveolar closure in ALI occurs over a wide range of pressures, and LIP is a poor predictor of alveolar closure.
.
The physics with energetic radioactive beams has had a tremendous development over the 30 years that have passed since Isao Tanihata’s famous experiments at Berkeley. The experiments and the ...subsequent understanding that halo structure occur for some very exotic nuclei have attracted so much interest and given so many novel ideas that one may speak about a paradigm shift. I shall here give some, personal, ideas about “What’s next”. This is an interesting task and I shall not say that it is difficult but rather challenging. I shall, however, start by giving a few milestones, preceding the 1985 break-through, that were of key importance for creating our sub-field of modern nuclear physics.
ISOLDE past, present and future Borge, Maria J G; Jonson, Björn
Journal of physics. G, Nuclear and particle physics,
04/2017, Letnik:
44, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The idea of production of short-lived radioisotopes with the on-line technique has it roots in the early 1950s. In 1964 this became a reality when CERN approved an experiment at the 600 MeV proton ...synchro-cyclotron, the SC. The first experiments were performed in 1967 and since then the ISOLDE programme has gradually developed into a major undertaking. Since 1992 the ISOLDE Radioactive Beam Facility is linked to an external proton beam from the PS Booster. Today this 50 years old 'lady' is more vital than ever. With the successful start of HIE-ISOLDE in 2015 one may conclude that the facility is ready to face the next half century with the boost of the success and the necessary knowledge to face new challenges. In this introductory article we give an overview of the history and pick up a few examples along the nuclear chart as illustrations of the experimental achievements.
Comprehensive Ventilation/Perfusion SPECT Palmer, John; Bitzen, Ulrika; Jonson, Bjorn ...
The Journal of nuclear medicine (1978),
08/2001, Letnik:
42, Številka:
8
Journal Article
Recenzirano
Lung scintigraphy is the primary tool for diagnostics of pulmonary embolism. A perfusion study is often complemented by a ventilation study. Intermediate probability scans are frequent. Our goal was ...to develop a fast method for tomographic ventilation and perfusion scintigraphy to improve the diagnostic value of lung scintigraphy.
SPECT was performed with a dual-head gamma camera. Acquisition parameters were determined using a thorax phantom. Ventilation tomography after inhalation of 30 MBq (99m)Tc-diethylenetriaminepentaacetate (DTPA) aerosol was, without patient movement, followed by perfusion tomography after an intravenous injection of 100 MBq (99m)Tc-labeled macroaggregated albumin (MAA). Total SPECT acquisition time was 20 min. (99m)Tc-DTPA clearance, calculated from initial and final SPECT projections, was used for correction of the ventilation projection set before iterative reconstruction of ventilation and perfusion. The ventilation background was subtracted from the perfusion tomograms. A normalized ventilation/perfusion quotient (V/P quotient) image set was calculated. The method was evaluated on a trial group of 15 patients.
Ventilation and perfusion images had adequate quality and showed ventilation/perfusion (V/Q quotient) relationships more clearly than did planar images. Frontal and sagittal slices were superior to planar scintigraphy for characterization of embolized areas. The V/Q quotient was supportive, particularly in the patients with chronic obstructive pulmonary disease.
Fast, high-quality, ventilation/perfusion SPECT with standard isotopes doses is feasible and may contribute to higher objectivity in evaluating lung embolism as well as other lung diseases. The costs for the procedure and patient care until diagnosis are low because of the comprehensive system for the study and, particularly, the short time for its completion.
Purpose
Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation which is not fully reversible. Despite the heterogeneity of COPD, its diagnosis and staging is currently ...based solely on forced expiratory volume in 1 s (FEV
1
). FEV
1
does not explain the underlying pathophysiology of airflow limitation. The relationship between FEV
1
, symptoms and emphysema extent is weak. Better diagnostic tools are needed to define COPD. Tomographic lung scintigraphy ventilation/perfusion single photon emission tomography (V/P SPECT) visualizes regional V and P. In COPD, relations between V/P SPECT, spirometry, high-resolution computed tomography (HRCT) and symptoms have been insufficiently studied. The aim of this study was to investigate how lung function imaging and obstructive disease grading undertaken using V/P SPECT correlate with symptoms, spirometric lung function and degree of emphysema assessed with HRCT in patients with COPD.
Methods
Thirty patients with stable COPD were evaluated with the Medical Research Council dyspnoea questionnaire (MRC) and the clinical COPD questionnaire (CCQ). Spirometry was performed. The extent of emphysema was assessed using HRCT. V/P SPECT was used to assess V/P patterns, total reduction in lung function and degree of obstructive disease.
Results
The total reduction in lung function and degree of obstructive disease, assessed with V/P SPECT, significantly correlated with emphysema extent (
r
= 0.66–0.69,
p
< 0.0001) and spirometric lung function (
r
= 0.62–0.74,
p
< 0.0005). The correlation between emphysema extent and spirometric lung function was weaker. No correlation between MRC, CCQ and objective measurements was found.
Conclusion
V/P SPECT is sensitive to early changes in COPD. V/P SPECT also has the possibility to identify comorbid disease. V/P SPECT findings show a significant correlation with emphysema extent and spirometric lung function. We therefore recommend that scintigraphic signs of COPD, whenever found, should be reported. V/P SPECT can also be used to categorize the severity of functional changes in COPD as mild, moderate or severe.
Lung scintigraphy is primarily used to diagnose pulmonary embolism. Ventilation imaging is often performed using Tc-99m-DTPA or Technegas, an ultrafine dispersion of Tc-99m-labeled carbon. Despite ...the common use of these radioaerosols, they have not been compared in an intraindividual study, and not with ventilation-perfusion (V/P) SPECT. The aim of the present head-to-head study was to systematically investigate differences in ventilation studies performed with Tc-99m-diethylenetriaminepentaacetate (DTPA) and Technegas. Methods: Sixty-three patients, 28 without and 35 with obstructive lung disease, were examined with V/P SPECT using both Tc-99m-DTPA and Technegas. V/P SPECT images were randomized and assessed independently by 2 masked physicians according to a predefined scoring system. A paired comparison was performed using the Wilcoxon signed-rank test. Results: In both obstructive and nonobstructive disease, the overall unevenness of radiotracer deposition and the degree of central deposition were more pronounced in Tc-99m-DTPA than Technegas studies. Because of better peripheral penetration, the extent of reverse mismatch was less when Technegas was used. Additionally, in obstructive disease, the degree of focal deposition in distal airways was more pronounced with Tc-99m-DTPA. Mismatched perfusion defects were more frequently found with Technegas in obstructive disease. Conclusion: This intraindividual comparative study shows that Technegas is the preferred radioaerosol, particularly in obstructive disease.
Letter to editor Bajc, Marika; Jonson, Björn
European journal of nuclear medicine and molecular imaging,
07/2020, Letnik:
47, Številka:
7
Journal Article
Letter to editor Bajc, Marika; Jonson, Björn
European journal of nuclear medicine and molecular imaging,
07/2020, Letnik:
47, Številka:
7
Journal Article
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