Watershed Regions Research Articles

Abstract No. 279: Incidence and detection of dual blood supply to hepatocellular carcinoma located in watershed regions of segment IV and VIII during transarterial chemoembolization

Hepatocellular carcinoma (HCC) located in watershed regions of segments IV and VIII are known to have arterial supply from both the left and the right hepatic arteries. In this study we report the incidence and detection of dual hepatic supply in HCC during transarterial chemoembolization. Implication on management of these tumors is also reported.

Sediments deposition due to soil erosion in the watershed region of Mangla Dam

Soil erosion is the most important reason of sedimentation load of water reservoirs in the world. In Pakistan, Mangla dam is one of the most important water reservoirs used for the production of electricity and for the supply of water for irrigation purposes. However, the capacity of Mangla dam reservoir has reduced by more than 20% since its construction. This study highlights the impact of rainfall on soil erosion and consequently on sedimentation deposition in Mangla dam reservoir. Sedimentation, annual rainfall, and normal rainfall data of 39 years were used in this study. Shuttle Radar Topographic Mission data were used to calculate the total drainage area of the Mangla watershed region. The sedimentation data of Mangla reservoir from 1967 to 2005 were retrieved from Water and Power Development Authority in Pakistan. The meteorological observatories in the Mangla watershed region are identified. Annual rainfall data from 1967 to 2005 for the meteorological observatories in the Mangla watershed regions were retrieved from Pakistan Meteorological Department (PMD). In addition, normal rainfall data for the years 1949 to 1978 and for the years 1979 to 2008 were also retrieved from PMD. The impact of annual rainfall is observed on sedimentation load in Mangla dam. The correlation coefficient between annual rainfall and sedimentation load is 0.94. This study shows that with an increase in rainfall, the soil erosion of the area increases which subsequently is responsible for the increase in the rate of sedimentation load in Mangla dam. This study further demonstrates that better soil management can reduce the sedimentation load in the Mangla reservoir.

Cerebral diffusion and perfusion deficits in North Sea divers

Diving is associated with a risk of cerebral decompression illness, and the prevalence of neurological symptoms is higher in divers compared with control groups. Microvascular dysfunction due to gas microembolism and exposure to hyperoxia are possible mechanisms, which may result in cerebral diffusion and perfusion deficits. To investigate if possible functional derangements of the microvasculature and microstructure would be more prevalent among symptomatic divers. Magnetic resonance imaging (MRI) was performed in 91 former divers and 45 controls. Individual parametric images of apparent diffusion coefficient (ADC), cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) were generated on the basis of diffusion- and perfusion-weighted imaging. To identify regions with statistically significant differences between groups (P < 0.05, corrected for false discovery rate), voxel-wise ANCOVA analysis was performed for each of the four parametric images. Significant regional group differences were found in all four parametric comparisons. Gross regional ADC differences were seen throughout the brain, including large frontal and temporal white-matter regions, the hippocampus, and parts of the cerebellum. Differences in the perfusion maps were localized in fewer and smaller clusters, including parts of the cerebellum, the putamen, and the anterior watershed regions. Regional functional abnormalities as measured by diffusion- and perfusion-weighted imaging were identified in the divers, and there was a partial co-localization of the regions identified in the perfusion and the diffusion images. The findings may explain some of the long-term clinical symptoms reported among professional divers.

A general framework for the analysis of vessel encoded arterial spin labeling for vascular territory mapping

Vessel encoded arterial spin labeling provides a way to perform non-invasive vascular territory imaging. By uniquely encoding the blood within feeding arteries over a number of images, the territories of each can be identified. Here, a new approach for the analysis of vessel encoded arterial spin labeling data is presented. The method includes a full description of how the geometry of arteries and spatial label modulation affects the measured signal. It also incorporates an artery-based classification that considers multiple arteries in each class, explicitly permitting a voxel to be supplied by multiple arteries. The developed framework is cast within a Bayesian inference procedure allowing both flow contributions and the locations of the arteries in the labeling plane to be inferred. By using simulated data, the method was shown to provide more accurate estimates of blood contribution in areas of mixed supply, such as would be found in watershed regions, than conventional methods. It was also able to estimate the location of arteries within the labeling plane, accounting for motion between sequence prescription and acquisition. Similar performance was found for data acquired using a pseudo-continuous labeling scheme both in the neck and above the Circle of Willis.

CT and MR in non-neonatal hypoxic–ischemic encephalopathy: radiological findings with pathophysiological correlations

Non-neonatal hypoxic-ischemic encephalopathy is a clinical condition often related to cardiopulmonary arrest that demands critical management and treatment decisions. Management depends mainly on the degree of neurological impairment and prognostic considerations. Computed tomography (CT) is often used to exclude associated or mimicking pathology. If any, only nonspecific signs such as cerebral edema, sulci effacement, and decreased gray matter (GM)/white matter (WM) differentiation are evident. Pseudosubarachnoid hemorrhage, a GM/WM attenuation ratio <1.18, and inverted GM attenuation are associated with a poor prognosis. Magnetic resonance (MR) imaging is more sensitive than CT in assessing brain damage in hypoxic-ischemic encephalopathy. Some MR findings have similarities to those seen pathologically, based on spatial distribution and time scale, such as lesions distributed in watershed regions and selective injury to GM structures. In the acute phase, lesions are better depicted using diffusion-weighted imaging (DWI) because of the presence of cytotoxic edema, which, on T2-weighted images, only become apparent later in the early subacute phase. In the late subacute phase, postanoxic leukoencephalopathy and contrast enhancement could be observed. In the chronic phase, atrophic changes predominate over tissue signal changes. MR can be useful for estimating prognosis when other tests are inconclusive. Some findings, such as the extent of lesions on DWI and presence of a lactate peak and depleted N-acetyl aspartate peak on MR spectroscopy, seem to have prognostic value.

The Black Flies (Diptera: Simuliidae) of New Jersey, U.S.A.

Black fly larvae and pupae were collected from eighteen New Jersey (NJ) counties spanning all five physiographic provinces, and all five watershed management regions. Collections were made year round from small, medium, and large sized streams, and yielded a total of 40 black fly species in five genera. These collections include three new occurrence records for NJ, Simulium vittatum, S. notiale, and S. definitum; and complete NJ collection data for S. anchistinum. New county occurrence records for Prosimulium canutum, P. clandestinum, S. impar, S. parnassum and S. vandalicum are also reported. Collections included four NJ Simulium species limited to the Coastal Plain, and three species restricted to the upper Delaware River in NJ. The most pestiferous group of NJ black flies, the S. jenningsi group, was represented by seven species found in all five physiographic provinces of the state. A region along the eastern glacial terminus which includes northern NJ supports a regional simuliid species diversity that is among the highest in North America.

Long‐term patterns of dissolved organic carbon in lakes across eastern Canada: Evidence of a pronounced climate effect

We analyzed the 21‐yr dynamics of dissolved organic carbon (DOC) in 55 lakes during ice‐free periods in five regions across eastern Canada in relation to total solar radiation (TSR), precipitation, air temperature, sulfate deposition (SO4), Southern Oscillation Index (SOI), North Atlantic Oscillation, and Pacific Decadal Oscillation (PDO). A synchronous pattern in DOC was found among lakes within each region; however, a synchronous pattern in DOC was not found among regions, except for Kejimkujik and Yarmouth. Long‐term trends of increasing or decreasing DOC concentration were not evident except at the Experimental Lakes Area (ELA), where an increase in DOC correlated with a decrease in summer TSR and an increase in summer precipitation. Annual mean temperature increased at the Nova Scotia and Turkey Lakes Watershed regions (TLW) over the study period, but there was no corresponding change in DOC. TSR and precipitation were important explanatory variables across all regions, except for the TLW. Summer TSR, or annual TSR, had a negative relationship, while summer precipitation had a positive relationship with the temporal DOC pattern in all regions except TLW. TSR and precipitation explained 78%, 49%, and 84% of the variation in the long‐term DOC patterns at Dorset, ELA, and Nova Scotia (NS) regions, respectively. In contrast, the long‐term pattern in DOC at TLW was only weakly related to SOI and PDO.

Is patent foramen ovale closure indicated for migraine?

Is patent foramen ovale closure indicated for migraine?

Alemtuzumab in the reversal of encephalopathy associated with hypereosinophilic syndrome

A 63-year-old woman who had a 1-year history of FIP1L1PDGFRa-negative hypereosinophilic syndrome, presented with the sudden onset of ataxia and strength loss in lower extremities, spatial disorientation, and neglect of the left side of her body. She had an eosinophil count of 161AE8 · 10/l. Brain magnetic resonance imaging (MRI) with fluid-attenuated inversion recovery (FLAIR) sequence showed extensive bilateral and diffuse abnormalities situated in watershed regions (left panel). Therapy with corticosteroids, hydroxycarbamide, interferon-a (5 000 000 units/day), and low-dose subcutaneous cytarabine (20 mg/day) was effective in reducing her eosinophil count, which stabilized at 40 · 10/l. Neurological symptoms were also stable. Four months after this presentation, the patient was readmitted with significant worsening of her neurological symptoms, with cerebellar ataxia and urinary incontinence. The patient was treated with subcutaneous alemtuzumab at a dose of 30 mg/week. She had an excellent response, with the eosinophil count stabilizing at 5 · 10/l after three doses, achieving a partial haematological response. A 6-month MRI follow-up showed decrease in the size of the lesions (right panel).

Abstract No. 187: Impact of C-Arm CT on Treatment Planning in Patients Undergoing Chemembolization for Tumors Located in Segments with Watershed Arterial Supply

To evaluate the impact of C-arm CT on treatment algorithms in patients undergoing chemoembolization for hepatocellular carcinoma (HCC) in regions that have dual or variable arterial supply (segment IV, segment I, medial portions of segments VII and V, referred to as watershed regions). From March to July 2008, 14 patients (39-78 years old, mean 61.7 years) with HCC in watershed regions underwent chemoembolization. Mean tumor diameter was 2.5 cm (range 1 cm - 5.7 cm). Non-contrast and selective arterially- enhanced C-arm CT acquisitions (8 second rotational scan of ∼200 degrees) with 3D reconstruction were obtained in addition to conventional digital subtraction angiograms (DSA) in all patients. Impact on diagnosis and treatment was categorized as: a) identification of additional lesions not seen on DSA; b) evaluation of completeness of ethiodol uptake in the tumor and need for additional selective catheterization and chemoembolization; c) depiction of multiple arteries supplying the tumor and identification of the dominant vessel; and/or d) facilitation of selective catheterization of complex vascular anatomy. All cases were technically successful. C-arm CT had a significant impact on the treatment plan in 9 of the 14 patients (64.3%). In 4 patients (28.6%), the tumor(s) was not conspicuous on DSA, but was identified on C-arm CT, allowing accurate targeting. C-arm CT identified incomplete target embolization due to dual arterial supply to the tumor in five patients (35.7%) that was not apparent on DSA, leading to additional catheterization and embolization to complete treatment. In one patient (7.1%), C-arm CT was crucial in delineating the segmental arterial vessels supplying the tumor and providing 3D mapping for successful catheterization. C-arm CT has become a crucial tool in the diagnosis and treatment of patients undergoing chemoembolization for HCCs located in watershed regions and exceeds the capabilities of DSA in a majority of the patients.

Region-based image retrieval using color-size features of watershed regions

This paper presents a region-based image retrieval system that provides a user interface for helping to specify the watershed regions of interest within a query image. We first propose a new type of visual features, called color-size feature, which includes color-size histogram and moments, to integrate color and region-size information of watershed regions. Next, we design a scheme of region filtering that is based on color-size histogram to fast screen out some of most irrelevant regions and images for the preprocessing of the image retrieval. Our region-based image retrieval system applies the Earth Mover’s Distance in the design of the similarity measure for image ranking and matching. Finally, we present some experiments for the color-size feature, region filtering, and retrieval results that demonstrate the efficiency of our proposed system.

REGION SIMILARITY RELATIONSHIP BETWEEN WATERSHED AND PENALIZED FUZZY HOPFIELD NEURAL NETWORK ALGORITHMS FOR BRAIN IMAGE SEGMENTATION

A robust image segmentation method that combines the watershed segmentation and penalized fuzzy Hopfield neural network (PFHNN) algorithms to minimize undesirable over-segmentation is described in this paper. This method incorporates spatial graph representation derived from the watershed segmented regions and cluster analysis information obtained from the PFHNN algorithm to achieve efficient image segmentation. The proposed scheme employs the Markov random field (MRF) model on the region adjacency graph (RAG) to improve the quality of watershed segmentation. Here, the fusion criterion is according to the correlation coefficient, which uses inter-region similarities to determine the merging of regions. Analysis of the performance of the proposed technique is presented through quantitative and qualitative validation experiments on benchmark images, and significant and promising segmentation results are presented using brain phantom simulated data.

Fertilizer Nitrogen Practices and Nitrate Levels in Surface Water within an Illinois Watershed

Proper nitrogen (N) management as it relates to crop yield has become a critical concern due to the environmental impacts of excessive N fertilizer application. This study monitored 36 sites within the Lake Bloomington, Illinois, watershed on a weekly basis to determine nitrate-N concentrations from various surface water sources. Average nitrate-N concentrations for the period 1993 to 2002 revealed the following: agricultural production drainage tiles, 17.0 mg/L; creek water (Money Creek tributary), 12.0 mg/L; organic agriculture drainage tiles, 11.4 mg/L; surface water runoff, 6.6 mg/L; wooded pasture drainage tiles, 1.6 mg/L; and rainwater, 1.2 mg/L. In addition, as creek water passed through a small municipality (urban effect), its concentration of nitrate-N dropped by an average of 0.6 mg/L. An initial watershed resident survey and an annual N fertilizer use survey were conducted to ascertain common N management practices of agricultural producers within the watershed. The mean expected corn grain yield was 9845 kg/ha and the median N fertilizer application rate was between 169 and 202 kg N/ha. On average, 54.5% of the N fertilizer in the watershed was applied in the fall, 32.5% was applied in the spring before planting, and 12.7% was applied after planting. Within the watershed, 64% nonfarming residents perceived agricultural crop production as having the greatest negative impact on water quality compared with only 15.6% of those actively engaged in farming. Knowledge from this study can be used to develop recommendations for sound N management practices within sensitive watershed regions.

변동유형 분석법을 이용한 해수침투 관측망 자료 평가

우리나라 서, 남해안에 지하수의 해수침투 현상을 관측하기 위해 설치된 관측망 자료를 이용하여, 해당지역별 대수층을 통한 해수침투의 유형을 분석하였다. 분석에 이용된 관측정은 25개 해안지역 소유역의 총 45개 암반관정으로, 지하수위, 수온, 전기전도도를 대상으로 기본통계분석, 상관성 분석 및 변동유형 분류를 수행하였다. 분석 결과 지하수위의 경우 강우 영향을 받거나 양수에 의한 수위강하가 나타나는 관측정에서 큰 폭으로 변동하고 있다. 지하수온은 대부분의 경우 변동폭이 <TEX>$0.2^{\circ}C$</TEX> 이내로 안정적인 특징을 보여주고 있으며, 전체적으로 평균 온도가 <TEX>$15^{\circ}C$</TEX> 이상으로 나타났다. 전기전도도의 경우 상대적으로 변동폭이 크고 불규칙한 특징을 가지고 있으며, 평균값이 <TEX>$2,000\;{\mu}S/cm$</TEX> 이내의 관측정이 28개, <TEX>$10,000\;{\mu}S/cm$</TEX>를 초과하는 관측정은 9개소로 나타났다. 교차상관도 분석에 의하면, 지하수위는 강우의 영향을 받아 변동하는 형태가 많았지만 수온과 전기전도도는 상대적으로 강우의 영향이 없는 것으로 나타났다. 조석의 경우에는 일부 관측정에서 강우에 의한 영향보다 높은 교차상관도가 나타났다. 본 연구에서는 장기관측자료를 변동형태에 따라 정상형, 추세형, 주기형, 충동형, 계단형, 경사형 등 6가지로 분류하였다. 지하수위의 경우 강우나 양수의 영향을 받는 충동형이 가장 많은 73.3%이며, 조석의 영향은 13.4%에 해당되었다. 지하수온의 경우 변동폭이 일정한 정상형태가 51.2로 가장 높게 나타났으며, 강우나 양수에 의한 충동형이 26.7%에 해당되었다. 전기전도도의 경우는 지하수위나 지하수온과 달리 추세형, 계단형, 경사형 등의 변동형태가 우세한 것으로 나타났다. 전체적으로 동일한 해안지역에 설치된 관측정별로 관측자료의 변동 특성이 상이한 경우가 나타남에 따라, 향후 각 소유역별로 관측정 자료의 정기적인 변동 경향성을 분석하는 것이 필요하다. With groundwater data of seawater intrusion monitoring network in coastal areas of Korea's main land, we analyzed types of seawater intrusion through the coastal aquifer. The data including groundwater level, temperature and electrical conductivity obtained from 45 monitoring wells at 25 watershed regions were evaluated. Based on statistical analysis, correlation analysis and variation type analysis, groundwater levels were mainly affected by rainfall and artificial pumping. About 78% of the monitoring wells showed average temperature higher than <TEX>$15^{\circ}C$</TEX> and about 58% of them showed minimum variations less than <TEX>$0.2^{\circ}C$</TEX>. Electrical conductivities showed a large magnitude of variation and irregular characteristics compared with groundwater levels and temperatures. Average electrical conductivities lower than <TEX>$2,000\;{\mu}S/cm$</TEX> were observed at 28 monitoring wells while those of higher than <TEX>$10,000\;{\mu}S/cm$</TEX> were done at 9 monitoring wells. From the cross-correlation analysis, groundwater levels were mostly affected by precipitation while temperature and electrical conductivity showed very low correlation. Meanwhile tidal variations strongly affected the groundwater levels comparing to precipitation. We classified the long-term monitoring data according to variation types such as constant process, linear trend, cyclic variation, impulse, step function and ramp. Impulse type was dominant for variations of groundwater level, which was largely affected by rainfall or artificial pumping, the constant process was dominant for temperature. Compared with groundwater level and temperature, electrical conductivities showed various types like linear trend, step function and ramp. According to the discrepancy of variation characteristics for monitoring data at each well in the same region, periodical analysis of monitoring data is essentially required.

Holocene Climates and Connections between the San Francisco Bay Estuary and its Watershed: A Review

Climate over the watershed of the San Francisco Bay Delta estuary system varies on a wide range of space and time scales, and affects downstream estuarine ecosystems. The historical climate has included mild to severe droughts and torrential rains accompanied by flooding, providing important lessons for present-day resource managers. Paleoclimate records spanning the last 10,000 years, synthesized across the Estuary, watershed and key regions beyond, provide a basis for increased understanding of how variable California’s climate can be and how it affects the Bay Delta system.This review of paleoclimate records reveals a gradual warming and drying in California from about 10,000 years to about 4,000 years before present. During this period, the current Bay and Delta were inundated by rising sea level so that by 4,000 years ago the Bay and Delta had taken on much of their present shape and extent. Between about 4,000 and 2,000 years ago, cooler and wetter conditions prevailed in the watershed, lowering salinity in the Estuary and altering local ecosystems. Those wetter conditions gave way to increasing aridity during the past 2,000 years, a general trend punctuated by occasional prolonged and severe droughts and occasional unusually wet, cool periods. California’s climate since A.D. 1850 has been unusually stable and benign, compared to climate variations during the previous 2,000 or more years. Thus, climate variations in California’s future may be even more (perhaps much more) challenging than those of the past 100 years. To improve our understanding of these past examples of climate variability in California, and of the linkages between watershed climate and estuarine responses, greater emphases on paleoclimate records in and around the Estuary, improved temporal resolutions in several record types, and linked watershed-estuary paleo-modeling capabilities are needed.

Three-dimensional cerebral vasculature of the CBA mouse brain: A magnetic resonance imaging and micro computed tomography study

Studies of mouse cerebral vasculature to date have focused on the circle of Willis without examining the morphological distribution of blood vessels through the rest of the brain. Since mouse models are frequently used in brain-related studies, there is a need for a comprehensive cerebral vasculature atlas for the mouse with an emphasis on the location of vessels with respect to neuroanatomical structures, the watershed regions associated with specific arteries, as well as a consistent nomenclature of the cerebral vessels. This article describes such an atlas, based on a combination of magnetic resonance and computed tomography technology to yield high-resolution volumetric and vasculature data on CBA mouse. This three-dimensional vasculature dataset provides an anatomical resource for future mouse studies.

Can Cognition Survive Heart Surgery?

In this issue of Circulation , Jensen et al1 report that cognitive difficulties were no fewer when off-pump (OPCAB) versus conventional (CCAB) coronary artery bypass grafting was used. This important investigation, a substudy of the Best Bypass Surgery Trial, is a randomized prospective controlled trial that compares OPCAB with CCAB. Although the numbers seem relatively small (ie, 120 elderly patients with a men age of 76 years), the study was carefully powered to show differences in cognitive function at a mean of 103 days of follow-up. Although one could quibble with the details of the neuropsychological tests chosen (mini-mental state examination as a screening test for dementia after randomization but before inclusion, visual verbal learning, concept shifting, Stroop color word interference test, letter-digit coding), the main result is unequivocal. The incidence of cognitive decline was roughly 8%, and no difference between OPCAB and CCAB was found. This disappointing result raises important questions about the mechanisms of neurological injury caused by cardiac surgery and what future strategies might entail. Article p 2790 Early in the development of cardiac surgery, it was psychiatrists who first reported difficulties with thought content and process. Rizzo et al2 reported on 32 patients under the care of Lewis Dexter (cardiologist) and Dwight Harken (cardiac surgeon) who underwent “finger fracture” valvuloplasty surgery for rheumatic mitral valve disease at the Peter Bent Brigham Hospital in Boston. These psychiatrists applied analytical explanations (eg, hysterical fantasies as the heart as a sexual organ, transference to the surgeon, depersonalization, narcissism) to their findings of disordered thinking in many of their patients. Only 50 years later, these explanations sound amusingly antique, but they mark the first organized recognition that the brain could suffer serious damage as a result of cardiac surgery. The neurological complications of cardiac surgery fall into 2 …

Deep White Matter Pathologic Features in Watershed Regions

Myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome typically manifests in adults younger than 40 years with encephalopathy, stroke-like episodes, and lactic acidosis. Magnetic resonance imaging (MRI) abnormalities typically involve the cortical gray and the adjacent subcortical white matter. To describe a 58-year-old woman diagnosed with MELAS who was initially seen with acute myopathy, cardiac ischemia, psychosis, and MRI changes in a watershed distribution. Initial MRI of the brain showed the characteristic parieto-occipital gray matter lesions involving the adjacent white matter. Follow-up MRI revealed striking deep white matter involvement in a watershed distribution. A cerebral angiogram and thorough hypercoagulable workup results were normal. Electromyography showed acute denervation and myopathy. A muscle biopsy specimen revealed ragged red and cytochrome-c oxidase-negative fibers. Mitochondrial DNA analysis revealed an A3243G mutation. Myopathy, encephalopathy, lactic acidosis, and stroke-like episodes should be considered in older patients with myopathy, cardiomyopathy, encephalopathy, and unaccountable MRI findings. Watershed pathologic features are a rare pattern of cerebral involvement in MELAS.

Neuroprotection in Cardiac Surgery

Several hundred thousand patients in the United States undergo cardiac surgery. The most common procedures include those for coronary artery disease, valvular heart disease, aortic disease, surgery for heart failure, congenital heart disease, transplantation, and a variety of other combined procedures. Neurologic injury is a significant risk factor for patients undergoing cardiac surgery. Although stroke, with an incidence of 1% to 6%, is the most serious complication, cognitive impairment (25% to 65%) and impaired level of consciousness (approximately 10%) can be significantly troublesome for patients and lead to potential further complications [1]. This latter complication can consist of encephalopathy, delirium, confusion, and depression. Atherosclerotic emboli from the aorta and great vessels and hypoperfusion to watershed regions of the brain are the predominant causes of stroke (or cerebrovascular accident). The cause of cognitive impairment and impaired level of consciousness is multifactorial and has been attributed to hypoperfusion, microemboli, metabolic derangements, general anesthesia, and initiation of a proinflammatory state.

Brain Perfusion Abnormalities in Neurologically Asymptomatic Adult Patients with Sickle Cell Disease. A Voxel-Based Analysis of Brain Spect Imaging.

Sickle cell diseases (SCD) are characterized by the presence of hemoglobin S, hemolytic anemia and vascular occlusion. Silent infarcts in SCD patients is strongly associated with an increased stroke risk and progressive cognitive decline. In this study we used 99mTc-ECD single photon emission computerized tomography (SPECT) in order to detect early abnormalities of brain perfusion in neurologically asymptomatic adult SCD patients. We recruited 42 SCD (27 females and 15 males, mean age of 33.4±10.55, range 17–60 years) from the Hematology and Hemotherapy Center of the University of Campinas.The SCD types were distributed as follows: 33 HbSS (14 males and 19 females), 6 HbSC (1 male and 5 females) and 3 HbSBeta (3 females). Mean steady state hemoglobin level measured in the period of up to 2 weeks before or after imaging acquisition was 8.5g/dl (±1.73; 5.2–13.5) and mean hematocrit was 25.1% (±4.85; 15.6–38.5). The group of patients with SCD was compared to a group of control healthy subjects (29 females and 20 males with mean age 31 years ±8; 25–49) recruited within the local community, who were submitted to the same imaging protocol used in the patients.The study was approved by the National Ethical Committee Board and informed-write consent was obtained from all patients. The inclusion criteria for this study was to be at least 17 years old, have a precise clinical and laboratory diagnosis of any SCD, do not have stroke previously and be on regular follow-up in the clinic. All of them were submitted to a standard protocol of brain SPECT image acquisition. Reconstructed transaxial datasets were converted into ANALYZE format and corrected for the orthogonal plane of acquisition using MRIcro software. Voxel-based analysis was performed using SPM2 (Wellcome Department of Cognitive Neurology). Images were spatially normalized to standard anatomical template defined in the atlas of Talairach and Tournoux. The normalized smoothed images underwent group comparison of regional tracer uptake using paired t-test. Contrasts were defined in order to estimate the probability of each voxel to have an increased or decreased tracer uptake in images from patients with SCD compared to images from the normal control group. Reduced tracer uptake was observed in many areas of the brain when compared to normal controls. These areas corresponded predominantly to watershed regions and other brain areas supplied by micro vasculature. We observed a reduced tracer uptake in the central basal forebrain, which includes the basal ganglia and thalami, the anterior frontal region and the watershed region of the temporo-parietal-occipital transition. These regions are to be considered the most significant hypoperfused areas (false discovery rate correction of p<0.05).The findings of our study demonstrate that neurologically asymptomatic SCD patients exhibit a pattern of reduced 99mTc-ECD tracer uptake demonstrated by SPECT. Early diagnosis of such cerebral vasculopathy has prognostic implications and can be determinant in considering therapeutic alternatives to avoid increasing in brain lesion load and progressive disability.