Cost-effective restoration for carbon sequestration across Brazil's biomes.

Tropical ecosystems are central to the global focus on halting and reversing habitat destruction as a means of mitigating carbon emissions. Brazil has been highlighted as a vital part of global climate agreements because, whilst ongoing land-use change causes it to be the world's fifth biggest greenhouse gas emitting country, it also has one of the greatest potentials to implement ecosystem restoration. Global carbon markets provide the opportunity of a financially viable way to implement restoration projects at scale. However, except for rainforests, the restoration potential of many major tropical biomes is not widely recognised, with the result that carbon sequestration potential may be squandered. We synthesize data on land availability, land degradation status, restoration costs, area of native vegetation remaining, carbon storage potential and carbon market prices for 5475 municipalities across Brazil's major biomes, including the savannas and tropical dry forests. Using a modelling analysis, we determine how fast restoration could be implemented across these biomes within existing carbon markets. We argue that even with a sole focus on carbon, we must restore other tropical biomes, as well as rainforests, to effectively increase benefits. The inclusion of dry forests and savannas doubles the area which could be restored in a financially viable manner, increasing the potential CO2e sequestered >40 % above that offered by rainforests alone. Importantly, we show that in the short-term avoiding emissions through conservation will be necessary for Brazil to achieve it's 2030 climate goal, because it can sequester 1.5 to 4.3 Pg of CO2e by 2030, relative to 0.127 Pg CO2e from restoration. However, in the longer term, restoration across all biomes in Brazil could draw down between 3.9 and 9.8 Pg of CO2e from the atmosphere by 2050 and 2080.

A framework for estimating forest disturbance intensity from successive remotely sensed biomass maps: moving beyond average biomass loss estimates.

BACKGROUND: The success of satellites in mapping deforestation has been invaluable for improving our understanding of the impacts and nature of land cover change and carbon balance. However, current satellite approaches struggle to quantify the intensity of forest disturbance, i.e. whether the average rate of biomass loss for a region arises from heavy disturbance focused in a few locations, or the less severe disturbance of a wider area. The ability to distinguish between these, very different, disturbance regimes remains critical for forest managers and ecologists. RESULTS: We put forward a framework for describing all intensities of forest disturbance, from deforestation, to widespread low intensity disturbance. By grouping satellite observations into ensembles with a common disturbance regime, the framework is able to mitigate the impacts of poor signal-to-noise ratio that limits current satellite observations. Using an observation system simulation experiment we demonstrate that the framework can be applied to provide estimates of the mean biomass loss rate, as well as distinguish the intensity of the disturbance. The approach is robust despite the large random and systematic errors typical of biomass maps derived from radar. The best accuracies are achieved with ensembles of ≥1600 pixels (≥1 km2 with 25 by 25 m pixels). SUMMARY: The framework we describe provides a novel way to describe and quantify the intensity of forest disturbance, which could help to provide information on the causes of both natural and anthropogenic forest loss-such information is vital for effective forest and climate policy formulation.

Constraining ecosystem processes from tower fluxes and atmospheric profiles.

The planetary boundary layer (PBL) provides an important link between the scales and processes resolved by global atmospheric sampling/modeling and site-based flux measurements. The PBL is in direct contact with the land surface, both driving and responding to ecosystem processes. Measurements within the PBL (e.g., by radiosondes, aircraft profiles, and flask measurements) have a footprint, and thus an integrating scale, on the order of 1-100 km. We use the coupled atmosphere-biosphere model (CAB) and a Bayesian data assimilation framework to investigate the amount of biosphere process information that can be inferred from PBL measurements. We investigate the information content of PBL measurements in a two-stage study. First, we demonstrate consistency between the coupled model (CAB) and measurements, by comparing the model to eddy covariance flux tower measurements (i.e., water and carbon fluxes) and also PBL scalar profile measurements (i.e., water, carbon dioxide, and temperature) from Canadian boreal forest. Second, we use the CAB model in a set of Bayesian inversions experiments using synthetic data for a single day. In the synthetic experiment, leaf area and respiration were relatively well constrained, whereas surface albedo and plant hydraulic conductance were only moderately constrained. Finally, the abilities of the PBL profiles and the eddy covariance data to constrain the parameters were largely similar and only slightly lower than the combination of both observations.

Diffuse, intense lung uptake on a bone scan: a case report.

PURPOSE: Clinical and scintigraphic findings are described in a patient with unexpected diffuse lung uptake on bone scan after a heroin overdose. METHODS: The patient's Tc-99m MDP bone scan is reviewed along with the pertinent clinical history and laboratory findings. RESULTS: Marked diffuse and symmetric lung uptake is present on bone scintigraphy in a patient with a history of acute renal failure and a markedly elevated calcium-phosphate product but normal renal function and laboratory values at the time of the examination. CONCLUSIONS: The incidental observation of metastatic calcification by bone scintigraphy is important, because it may aid in the diagnosis of a previously unsuggested elevated calcium-phosphate product, renal failure, or both. Furthermore, the intensity of tracer localization on bone tracer-specific imaging may help evaluate the activity of the metastatic calcification process.

A practical double-tuned 1H/31P quadrature birdcage headcoil optimized for 31P operation.

A double-tuned 1H/31P birdcage head coil for use with humans at 1.5 T is described. The coil was designed for proton-decoupled 31P excitation and reception and incorporated a number of practical features including optimized sensitivity for 31P, quadrature operation at 1H and 31P frequencies, and a radiofrequency (RF) mirror for improved B1 homogeneity. The design achieved similar B1 homogeneity at both 31P and 1H frequencies. Inductive matching was used to accommodate samples with large loading differences. A facile method for tuning and matching over a variety of sample loadings is presented, along with capacitively shortened bazookas for suppression of cable braid currents. The proton sensitivity, although down by approximately a factor of two compared with an optimized 1H birdcage head coil, was still ample for shimming and generation of scout images. Advantages of the design are discussed and proton-decoupled 31P spectra of human brain are presented.

Brain mapping with single photon emission CT.

PURPOSE: To investigate the feasibility of performing brain mapping studies by using cortical activation paradigms and single photon emission computed tomography (SPECT) and to evaluate methods of analysis. MATERIALS AND METHODS: Twenty healthy volunteers underwent technetium-99m bicisate SPECT under baseline conditions and during either full-field or right hemifield visual stimulation with a black and white reversing checkerboard pattern. Changes in regional cerebral perfusion were measured by using regions of interest (ROIs) and statistical parametric mapping. RESULTS: ROI analysis identified statistically significant increases in perfusion in the occipital cortex with full-field visual stimulation (mean +/- standard error of the mean percentage change from baseline: left, 8.0 +/- 1.5; right, 6.6 +/- 2.4). With right hemifield visual stimulation, perfusion was significantly increased only in the left occipital cortex (left, 5.2 +/- 1.5; right, -0.2 +/- 1.9). Statistical parametric mapping showed areas of activation (more than 100 voxel clusters showed significant change from baseline at a threshold value of P < or = .005 or z > or = 2.58) in the left primary visual cortex (right hemifield visual stimulation) and in both right and left primary visual areas (full-field visual stimulation). CONCLUSION: Brain mapping studies were preformed with Tc-99m bicisate SPECT, and activation-induced changes were visualized and measured. These methods can be applied to develop improved methods of diagnosis and assessment of treatment outcome in patients with neuropsychiatric disorders.

First-pass evaluation of myocardial output during dipyridamole stress using turbo-FLASH magnetic resonance imaging.

RATIONALE AND OBJECTIVES: This study evaluated the value of dynamically enhanced fast low-angle shot (FLASH) magnetic resonance (MR) imaging in measuring cardiac output with and without dipyridamole pharmacological stress. METHODS: Ten subjects underwent rest and stress MR imaging. Rest images were acquired using electrocardiogram gated MR (turbo-FLASH: repetition time = 6 mseconds; echo time = 12 mseconds; flip angle = 12 degrees, inversion time = 100) 10 to 45 seconds after intravenous bolus of 0.04 mmol/kg gadolinium (Gd)-DTPA using a Siemens 1.0-tesla Magnetom SP. Stress was induced within the MR imaging scanner with 0.56 mg/kg dipyridamole over 4 minutes with stress MR images obtained after a second bolus of Gd-DTPA in exactly the same position and time intervals. Cardiac output was calculated with a least squares error analysis before and after dipyridamole stress for the left and right ventricles in all 10 patients, and comparison was made with cardiac output by Fick dilution technique during cardiac catheterization in seven patients. RESULTS: This MR analysis methodology shows reasonable correlation (r = 0.953) between left ventricular and right ventricular cardiac output with no effect on cardiac output during immediate dipyridamole stress. Fick dilution studies demonstrated a correlation of 0.96. CONCLUSIONS: Turbo-FLASH MR can demonstrate time-activity curves and cardiac output calculations consistent with theoretical predictions.

Discordance of dual-isotope (hybrid) myocardial perfusion imaging results in patients who have undergone revascularization procedures.

Three hundred twenty-one separate acquisition dual-isotope myocardial perfusion scans were reviewed retrospectively. Studies performed in six patients demonstrated a relative improvement in Tc-99m sestamibi uptake during stress in segments that appeared abnormal on rest injected Tl-201 images. All patients who demonstrated this pattern had a prior history of myocardial infarction and interventional revascularization. While many factors may contribute to this appearance, the authors favor the presence of a patent infarct-related artery as being the most significant.

The use of personal computers in nuclear medicine.

Consolidating personal computers (PCs) with nuclear medicine technology can create high computational power comparable with that produced by vendor-specific computer equipment, and at more affordable prices. The integration of a standard platform and operating system with a large installed base has enabled our department to maintain itself at the cutting edge of technology with minimal expense. Along with the savings from the purchase of PC software and hardware come the added advantage of rapid training of staff with minimal in-house effort, especially given the vast educational support in the general community. The integration of a standard platform and operating system with a large installed base has provided the nuclear medicine department with computational resources once unheard of because of economies of scale. The acceptance and integration of a pervasive, flexible technology into nuclear medicine have shown that state-of-the-art studies can be performed at low cost.

SPET brain imaging with 201 diethyldithiocarbamate in acute ischaemic stroke.

Thirty-five patients with acute ischaemic stroke were studied within 24 h after hospital admission with thallium 201 diethyldithiocarbamate single photon emission tomography (201Tl-DDC SPET) and X-ray computed tomography (CT). 201Tl-DDC is a non-redistributing agent that allows postponed imaging after early administration and early therapeutic intervention. In 16 patients both investigations were performed within 24 h after stroke onset. The sensitivity of SPET was 94% and of CT 81% in the first 24 h, when hypodensity and obliteration of sulci were used as CT reading criteria. When only hypodensity was used as a criterion, the sensitivity of CT was 50% in this group. Sensitivity of CT compared with SPET became increasingly better in patients with older infarcts (1-18 days). In two-thirds of patients, the lesion demonstrated on SPET was larger than that on CT, and this was especially so with older infarcts. Crossed cerebellar diaschisis occurred in 69% of patients. The high sensitivity of 201Tl-DDC SPET in the first 24 h after ischaemic stroke and the favourable properties of this radiopharmaceutical make it a method of interest in the assessment of initial perfusion defects in early experimental stroke therapies.

Characterization of technetium-99m-L,L-ECD for brain perfusion imaging, Part 1: Pharmacology of technetium-99m ECD in nonhuman primates.

Technetium-99m ethyl cysteinate dimer ([99mTc]ECD) is a neutral, lipophilic complex which rapidly crosses the blood-brain barrier. Brain retention and tissue metabolism of [99mTc]ECD is dependent upon the stereochemical configuration of the complex. While both L,L and D,D enantiomers are extracted by the brain, only the L,L but not the D,D form, is metabolized and retained in the monkey brain (4.7% injected dose initially, T 1/2 greater than 24 hr). Dynamic single photon emission computed tomography imaging studies in one monkey indicates 99mTc-L,L-ECD to be distributed in a pattern consistent with regional cerebral blood flow for up to 16 hr postinjection. Dual-labeled 99mTc-L,L-ECD and [14C]iodoantipyrine autoradiography studies performed 1 hr after administration show cortical gray to white matter ratios of both isotopes to be equivalent (approximately 4-5:1). These data suggest that 99mTc-L,L-ECD will be useful for the scintigraphic assessment of cerebral perfusion in humans.

Biodistribution, dosimetry, and clinical evaluation of technetium-99m ethyl cysteinate dimer in normal subjects and in patients with chronic cerebral infarction.

Technetium-99m ethyl cysteinate dimer (ECD) has high initial cerebral uptake with slow clearance in nonhuman primates suggesting ideal characteristics for single photon emission computer tomography (SPECT) imaging. We evaluated the biodistribution, dosimetry and scintigraphic pattern of [99mTc]ECD in normal subjects and the accuracy of SPECT imaging in patients with chronic cerebral infarction. Sixteen normal subjects were injected with approximately 10 mCi of [99mTc]ECD. Anterior and posterior single-pass whole-body images were obtained at multiple times after injection. Blood clearance of the radiotracer was rapid, falling to 10.0 +/- 6.6% and 4.9 +/- 1.1% of the injected dose at 2 and 60 min, respectively. Brain uptake was 6.4 +/- 2.1% of the injected dose 5 min after injection. The critical organ was the urinary bladder. Technetium-99m ECD SPECT was performed with a rotating gamma camera in ten of the 16 normal subjects and 34 patients with clinical and CT evidence of chronic stroke. Thirty-three of the thirty-four patients had focal [99mTc]ECD abnormalities on SPECT (97.1%) based on visual inspection of the SPECT images. In summary, we obtained high quality SPECT images as a result of the optimal physical and biologic characteristics of the tracer. Technetium-99m ECD SPECT shows promise for the evaluation of patients with stroke.

Usefulness of dipyridamole-thallium-201 perfusion scanning for distinguishing ischemic from nonischemic cardiomyopathy.

To determine noninvasively the etiology of left ventricular (LV) dysfunction, 22 patients with a diagnosis of cardiomyopathy determined via cardiac catheterization and 5 normal control subjects underwent radionuclide ventriculography and intravenous dipyridamole-thallium-201 perfusion scanning. Both ischemically and nonischemically induced LV dysfunction had comparable global LV ejection fractions (24 +/- 6 vs 23 +/- 8%, respectively) and extent of segmental wall motion abnormalities. Right ventricular ejection fraction was significantly better in the group with an ischemic etiology of LV dysfunction (41 +/- 26 vs 13 +/- 10%, p less than 0.005) but significant group overlap was present. However, computer-assisted analysis of dipyridamole-thallium-201 myocardial perfusion scanning demonstrated more homogeneous myocardial perfusion in idiopathic cardiomyopathy (mean perfusion defect 25 +/- 11 vs 6 +/- 6%, p less than 0.001) and successfully predicted the correct etiology of LV dysfunction in 20 of 22 (91%) patients.