Reproducibility of arterial spin labeling cerebral blood flow image processing: A report of the ISMRM open science initiative for perfusion imaging (OSIPI) and the ASL MRI challenge.

PURPOSE: Arterial spin labeling (ASL) is a widely used contrast-free MRI method for assessing cerebral blood flow (CBF). Despite the generally adopted ASL acquisition guidelines, there is still wide variability in ASL analysis. We explored this variability through the ISMRM-OSIPI ASL-MRI Challenge, aiming to establish best practices for more reproducible ASL analysis. METHODS: Eight teams analyzed the challenge data, which included a high-resolution T1-weighted anatomical image and 10 pseudo-continuous ASL datasets simulated using a digital reference object to generate ground-truth CBF values in normal and pathological states. We compared the accuracy of CBF quantification from each team's analysis to the ground truth across all voxels and within predefined brain regions. Reproducibility of CBF across analysis pipelines was assessed using the intra-class correlation coefficient (ICC), limits of agreement (LOA), and replicability of generating similar CBF estimates from different processing approaches. RESULTS: Absolute errors in CBF estimates compared to ground-truth synthetic data ranged from 18.36 to 48.12 mL/100 g/min. Realistic motion incorporated into three datasets produced the largest absolute error and variability between teams, with the least agreement (ICC and LOA) with ground-truth results. Fifty percent of the submissions were replicated, and one produced three times larger CBF errors (46.59 mL/100 g/min) compared to submitted results. CONCLUSIONS: Variability in CBF measurements, influenced by differences in image processing, especially to compensate for motion, highlights the significance of standardizing ASL analysis workflows. We provide a recommendation for ASL processing based on top-performing approaches as a step toward ASL standardization.

Perfusion tomography in early follow-up of acute traumatic subdural hematoma: a case series.

Perfusion Computed Tomography (PCT) is an alternative tool to assess cerebral hemodynamics during trauma. As acute traumatic subdural hematomas (ASH) is a severe primary injury associated with poor outcomes, the aim of this study was to evaluate the cerebral hemodynamics in this context. Five adult patients with moderate and severe traumatic brain injury (TBI) and ASH were included. All individuals were indicated for surgical evacuation. Before and after surgery, PCT was performed and cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) were evaluated. These parameters were associated with the outcome at 6 months post-trauma with the extended Glasgow Outcome Scale (GOSE). Mean age of population was 46 years (SD: 8.1). Mean post-resuscitation Glasgow coma scale (GCS) was 10 (SD: 3.4). Mean preoperative midline brain shift was 10.1 mm (SD: 1.8). Preoperative CBF and MTT were 23.9 ml/100 g/min (SD: 6.1) and 7.3 s (1.3) respectively. After surgery, CBF increase to 30.7 ml/100 g/min (SD: 5.1), and MTT decrease to 5.8s (SD:1.0), however, both changes don't achieve statistically significance (p = 0.06). Additionally, CBV increase after surgery, from 2.34 (SD: 0.67) to 2.63 ml/100 g (SD: 1.10), (p = 0.31). Spearman correlation test of postoperative and preoperative CBF ratio with outcome at 6 months was 0.94 (p = 0.054). One patient died with the highest preoperative MTT (9.97 s) and CBV (4.51 ml/100 g). CBF seems to increase after surgery, especially when evaluated together with the MTT values. It is suggested that the improvement in postoperative brain hemodynamics correlates to favorable outcome.

The role of brain perfusion SPECT in the diagnosis of frontotemporal dementia: A systematic review.

BACKGROUND AND PURPOSE: Frontotemporal dementia (FTD) is the second most common cause of presenile dementia. The clinical distinction between FTD, Alzheimer's disease (AD), and other dementias is a clinical challenge. Brain perfusion SPECT may contribute to the diagnosis of FTD, but its value is unclear. METHODS: We performed a systematic review to investigate the diagnostic accuracy of the brain SPECT in (1) distinguishing FTD from AD and other dementias and (2) differentiating FTD variants. RESULTS: Overall, 391 studies were retrieved on the initial search and 35 studies composed the final selection, comprising a total number of 3142 participants of which 1029 had FTD. The sensitivity and the specificity for the differential diagnosis of FTD versus AD ranged from 56% to 88% and from 51% to 93%, respectively. SPECT is not superior to the clinical method of diagnosis, but the combination of SPECT with clinical data seems to improve the diagnostic accuracy. CONCLUSION: Brain perfusion SPECT has a limited value in the diagnostic framework of FTD. SPECT can be performed when FDG-PET is not available. SPECT is recommended only for selected cases when the diagnosis is challenging using conventional methods.

Compensatory contribution of retinal larger vessels to perfusion density in diabetics without retinopathy.

Vessel and perfusion densities may decrease before diabetic retinopathy appears; it is unknown whether these changes affect the contribution of vessel density to perfusion density. This was a non-experimental, comparative, prospective, cross-sectional study in non-diabetic subjects (group 1) and diabetics without retinopathy (group 2). Vessel and perfusion densities in the superficial capillary plexus were compared between groups at the center, inner, and full regions and by field (superior, temporal, inferior, nasal) using optical coherence tomography angiography. Coefficients of determination (R2) between vessel and perfusion densities were calculated to find the contribution of larger retinal vessels to perfusion density. Percent differences were used to evaluate the contribution of these vessels to perfusion density in a regression model. There were 62 participants, 31 eyes by group; vessel and perfusion densities as well as the coefficients of determination between them were lower in group 2, especially in the nasal field (R2 0.85 vs. 0.71), which showed a higher contribution of larger retinal vessels to perfusion density. The regression model adjusted to a quadratic equation. In diabetics without retinopathy the contribution of vessel density to perfusion density may decrease; a low vessel density may increase the contribution of larger retinal vessels to perfusion density.

Métodos ultrassonográficos na avaliação das afecções prostáticas em cães ­ revisão de literatura / Ultrasonographic methods in the evaluation of prostatic disorders in dogs ­ paper review

O objetivo desta revisão foi descrever as principais técnicas de avaliação e achados ultrassonográficos da próstata canina. A ultrassonografia é o método de escolha para avaliação da glândula prostática, sendo imprescindível como auxílio no diagnóstico na detecção de anormalidades, principalmente quando há suspeita da presença de tumores. Com inovação dos equipamentos, surgiram técnicas complementares à ultrassonografia modo Bidimensional (B), tais como Doppler, ultrassonografia contrastada e elastografia, que aumentam a acurácia diagnóstica. O Doppler fornece informações sobre arquitetura vascular e aspectos hemodinâmicos dos vasos sanguíneos. A ultrassonografia contrastada permite determinar parâmetros relacionados à perfusão sanguínea das estruturas pelos agentes de contraste (ex.: microbolhas), definindo, portanto, padrões de alta e baixa intensidade da arquitetura vascular. A elastografia proporciona a avaliação da rigidez tecidual tanto de forma qualitativa, por meio de elastogramas, quanto quantitativa, por meio das velocidades de cisalhamento. Espera-se que esta revisão possa contribuir com informações relevantes aos leitores e veterinários da área de ultrassonografia e reprodução animal.(AU)

The purpose of this review was to describe the main assessment techniques and ultrasound findings of the canine prostate. Ultrasonography is the method of choice for assessing the prostate gland, being essential as an aid in the diagnosis in the detection of abnormalities, especially when the presence of tumors is suspected. With the innovation of the equipment, complementary techniques to B-mode ultrasonography have emerged, such as Doppler, contrasted ultrasound and elastography, which increase the diagnostic accuracy. Doppler provides information on vascular architecture and hemodynamic aspects of blood vessels. Contrast ultrasonography allows to determine parameters related to the blood perfusion of structures by contrast agents (eg, microbubbles), thus defining high and low intensity patterns of vascular architecture. ARFI elastography provides assessment of tissue stiffness both qualitatively, using elastograms, and quantitative, using shear speeds. It is hoped that this review can contribute with relevant information to readers and veterinarians in the area of asound and animal reproduction.(AU)

Contrast optimization in arterial spin labeling with multiple post-labeling delays for cerebrovascular assessment.

OBJECTIVE: Improving the readout for arterial spin labeling with multiple post-labeling delays (multi-PLD ASL) through a flip angle (FA) sweep towards increasing contrast-to-noise ratio for long PLD images. METHODS: Images were acquired from 20 healthy subjects and 14 patients with severe, asymptomatic carotid artery stenosis (ACAS) in a 3T MRI scanner. Multi-PLD ASL images with conventional and proposed (FA sweep) readouts were acquired. For patients, magnetic resonance angiography was used to validate the multi-PLD ASL results. Perfusion values were calculated for brain regions irrigated by the main cerebral arteries and compared by analysis of variance. RESULTS: For healthy subjects, better contrast was obtained for long PLDs when using the proposed multi-PLD method compared to the conventional. For both methods, no hemispheric difference of perfusion was observed. For patients, the proposed method facilitated the observation of delayed tissue perfusion, which was not visible for long PLD using the conventional multi-PLD ASL. CONCLUSION: We successfully assessed brain perfusion of patients with asymptomatic CAS using multi-PLD ASL with FA sweep. We were able to show subtle individual differences. Moreover, prolonged arterial transit time in patients was observed, although they were considered asymptomatic, suggesting that it may not be an adequate term to characterize them.

COVID-19: What Iodine Maps From Perfusion CT can reveal-A Prospective Cohort Study.

BACKGROUND: Subtraction CT angiography (sCTA) is a technique used to evaluate pulmonary perfusion based on iodine distribution maps. The aim of this study is to assess lung perfusion changes with sCTA seen in patients with COVID-19 pneumonia and correlate them with clinical outcomes. MATERIAL AND METHODS: A prospective cohort study was carried out with 45 RT-PCR-confirmed COVID-19 patients that required hospitalization at three different hospitals, between April and May 2020. In all cases, a basic clinical and demographic profile was obtained. Lung perfusion was assessed using sCTA. Evaluated imaging features included: Pattern predominance of injured lung parenchyma in both lungs (ground-glass opacities, consolidation and mixed pattern) and anatomical extension; predominant type of perfusion abnormality (increased perfusion or hypoperfusion), perfusion abnormality distribution (focal or diffuse), extension of perfusion abnormalities (mild, moderate and severe involvement); presence of vascular dilatation and vascular tortuosity. All participants were followed-up until hospital discharge searching for the development of any of the study endpoints. These endpoints included intensive-care unit (ICU) admission, initiation of invasive mechanical ventilation (IMV) and death. RESULTS: Forty-one patients (55.2 ± 16.5 years, 22 men) with RT-PCR-confirmed SARS-CoV-2 infection and an interpretable iodine map were included. Patients with perfusion anomalies on sCTA in morphologically normal lung parenchyma showed lower Pa/Fi values (294 ± 111.3 vs. 397 ± 37.7, p = 0.035), and higher D-dimer levels (1156 ± 1018 vs. 378 ± 60.2, p < 0.01). The main common patterns seen in lung CT scans were ground-glass opacities, mixed pattern with predominant ground-glass opacities and mixed pattern with predominant consolidation in 56.1%, 24.4% and 19.5% respectively. Perfusion abnormalities were common (36 patients, 87.8%), mainly hypoperfusion in areas of apparently healthy lung. Patients with severe hypoperfusion in areas of apparently healthy lung parenchyma had an increased probability of being admitted to ICU and to initiate IMV (HR of 11.9 (95% CI 1.55-91.9) and HR 7.8 (95% CI 1.05-61.1), respectively). CONCLUSION: Perfusion abnormalities evidenced in iodine maps obtained by sCTA are associated with increased admission to ICU and initiation of IMV in COVID-19 patients.

Extended Time Window Mechanical Thrombectomy for Acute Stroke in Brazil.

BACKGROUND: Mechanical thrombectomy (MT) is the standard of care for acute ischemic stroke (AIS) caused by large vessel occlusion of the anterior circulation within 6 hours of symptoms onset and can be performed with an extended window up to 24 hours in selected patients. Nevertheless, the outcomes of MT with extended window are unknown in developing countries. OBJECTIVE: Explore the safety and efficacy of MT for AIS performed beyond 6 hours from symptoms onset in Brazil. METHODS: We reviewed data from AIS patients treated with MT beyond 6 hours of stroke onset, from 2015 to 2018 in a Brazilian public hospital. Patients had an occlusion of the intracranial internal carotid artery and/or proximal segment of the middle cerebral artery. CT Perfusion mismatch was evaluated using the RAPID® software. We evaluated the modified Rankin scale (mRS) and mortality at 90 days, and rate of symptomatic intracranial hemorrhage (sICH). RESULTS: Fifty-four patients were included, with a mean age of 65.6 ± 16.1 years, 55.6% were male, and the median NIHSS score at presentation was 17. Successful recanalization (TICI 2b to 3) was obtained in 92.6% of patients and sICH rate was 11.1%. Overall, 34% of the patients had a good outcome (mRS ≤2) at 90 days and the mortality rate was 20.3%. CONCLUSION: Our study, the first series of MT for AIS treated with extended window reported in Latin America, shows that MT can be performed with safety and lead to adequate functional outcomes in this context. Further studies should explore the barriers to broad implementation of MT for AIS in Latin America.

Neurovascular and perfusion imaging findings in coronavirus disease 2019: Case report and literature review.

Central nervous system involvement in severe acute respiratory syndrome caused by coronavirus disease 2019 (COVID-19) has increasingly been recognised in the literature, and possible mechanisms of neuroinvasion, neurotropism and neurovirulence have been described. Neurological signs have been described in 84% of COVID-19 intensive care unit patients, and haemostatic abnormalities in such patients may play an important role, with a broad spectrum of neuroimaging findings. This report describes the magnetic resonance imaging neurovascular findings in an acutely ill patient with COVID-19, including perfusion abnormalities depicted in the arterial spin labelling technique.

Lung Cavities in Chronic Thromboembolic Pulmonary Hypertension.

OBJECTIVES: Chronic thromboembolic pulmonary hypertension (CTEPH) is a unique form of pulmonary hypertension (PH) that arises from obstruction of the pulmonary vessels by recanalized thromboembolic material. CTEPH has a wide range of radiologic presentations. Commonly, it presents as main pulmonary artery enlargement, peripheral vascular obstructions, bronchial artery dilations, and mosaic attenuation patterns. Nevertheless, other uncommon presentations have been described, such as lung cavities. These lesions may be solely related to chronic lung parenchyma ischemia but may also be a consequence of concomitant chronic infectious conditions. The objective of this study was to evaluate the different etiologies that cause lung cavities in CTEPH patients. METHODS: A retrospective data analysis of the medical records of CTEPH patients in a single reference PH center that contained or mentioned lung cavities was conducted between 2013 and 2016. RESULTS: Seven CTEPH patients with lung cavities were identified. The cavities had different sizes, locations, and wall thicknesses. In two patients, the cavities were attributed to pulmonary infarction; in 5 patients, an infectious etiology was identified. CONCLUSION: Despite the possibility of being solely associated with chronic lung parenchyma ischemia, most cases of lung cavities in CTEPH patients were associated with chronic granulomatous diseases, reinforcing the need for active investigation of infectious agents in this setting.

Noncontrast CT versus Perfusion-Based Core Estimation in Large Vessel Occlusion: The Blood Pressure after Endovascular Stroke Therapy Study.

BACKGROUND AND PURPOSE: The 2018 AHA guidelines recommend perfusion imaging to select patients with acute large vessel occlusion (LVO) for thrombectomy in the extended window. However, the relationship between noncontrast CT and CT perfusion imaging has not been sufficiently characterized >6 hours after last known normal (LKN). METHODS: From a multicenter prospective cohort of consecutive adults who underwent thrombectomy for anterior LVO 0-24 hours after LKN, we correlated baseline core volume (rCBF < 30%) and the Alberta Stroke Program Early CT Scale (ASPECTS) score. We compared perfusion findings between patients with an unfavorable ASPECTS (<6) against those with a favorable ASPECTS (≥6), and assessed findings over time. RESULTS: Of 485 enrolled patients, 177 met inclusion criteria (median age: 69 years, interquartile range [IQR: 57-81], 49% female, median ASPECTS 8 [IQR: 6-9], median core 10 cc [IQR: 0-30]). ASPECTS and core volume moderately correlated (r = -.37). A 0 cc core was observed in 54 (31%) patients, 70% of whom had ASPECTS <10. Of the 28 patients with ASPECTS <6, 3 (11%) had a 0 cc core. After adjustment for age and stroke severity, there was a lower ASPECTS for every 1 hour delay from LKN (cOR: 0.95, 95% confidence of interval [CI]: 0.91-1.00, P = .04). There was no difference in core (P = .51) or penumbra volumes (P = .87) across patients over time. CONCLUSIONS: In this multicenter prospective cohort of patients who underwent thrombectomy, one-third of patients had normal CTP core volumes despite nearly three quarters of patients showing ischemic changes on CT. This finding emphasizes the need to carefully assess both noncontrast and perfusion imaging when considering thrombectomy eligibility.

Lung cavities in chronic thromboembolic pulmonary hypertension

OBJECTIVES: Chronic thromboembolic pulmonary hypertension (CTEPH) is a unique form of pulmonary hypertension (PH) that arises from obstruction of the pulmonary vessels by recanalized thromboembolic material. CTEPH has a wide range of radiologic presentations. Commonly, it presents as main pulmonary artery enlargement, peripheral vascular obstructions, bronchial artery dilations, and mosaic attenuation patterns. Nevertheless, other uncommon presentations have been described, such as lung cavities. These lesions may be solely related to chronic lung parenchyma ischemia but may also be a consequence of concomitant chronic infectious conditions. The objective of this study was to evaluate the different etiologies that cause lung cavities in CTEPH patients. METHODS: A retrospective data analysis of the medical records of CTEPH patients in a single reference PH center that contained or mentioned lung cavities was conducted between 2013 and 2016. RESULTS: Seven CTEPH patients with lung cavities were identified. The cavities had different sizes, locations, and wall thicknesses. In two patients, the cavities were attributed to pulmonary infarction; in 5 patients, an infectious etiology was identified. CONCLUSION: Despite the possibility of being solely associated with chronic lung parenchyma ischemia, most cases of lung cavities in CTEPH patients were associated with chronic granulomatous diseases, reinforcing the need for active investigation of infectious agents in this setting.

Role of low dose 256-slice CT perfusion imaging in predicting mediastinal lymph node metastasis of lung cancer.

OBJECTIVE: CT perfusion (CTP) is an imaging technique that can be used to evaluate the changes in the microcirculation of tumor tissues. Our study aimed to investigate the role of CTP in predicting mediastinal lymph node metastasis. METHODS: Clinical data of 58 patients who received surgical resection of lung cancer and lymph node dissection in our hospital from June 2012 to December 2014 were collected. Patients were divided into a positive lymph node metastasis group and a negative lymph node metastasis group. Parameters of CTP, including peak enhancement intensity (PEI), perfusion value (PV), as well as blood volume (BV), were compared between the two groups. The receiver-operating characteristic (ROC) curve was used to predict mediastinal lymph node metastasis. RESULTS: The PV of the positive lymph node metastasis group was significantly higher than that of the negative group (p < 0.001). The ROC curve analysis showed that PV can be used as an index to predict mediastinal lymph node metastasis of lung cancer. The sensitivity and specificity of a PV greater than 7.5ml·min-1·ml-1 in predicting lymph node metastasis of lung cancer were 78.3 % and 91.4 %, respectively. CONCLUSION: The PV of low dose CT perfusion can be used as an index for predicting mediastinal lymph node metastasis of lung cancer.

Multicenter Volumetric Assessment of Artifactual Hypoperfusion Patterns using Automated CT Perfusion Imaging.

BACKGROUND AND PURPOSE: Automated computed tomography perfusion (CTP) is recommended to inform selection of stroke patients for thrombectomy >6 hours from last known normal (LKN). However, artifacts on automated perfusion output may overestimate the tissue at risk leading to misclassification of thrombectomy eligibility in some patients. METHODS: We conducted a retrospective multisite study of consecutive patients with anterior large vessel occlusion (LVO) undergoing CTP (6/2017-12/2017). The primary outcome was the RAPID automated Tmax  > 6 seconds volume that was discordant with clinical symptoms and vessel imaging, manually assessed by two independent readers. The discordant penumbral volume was compared to the automated output and corrected mismatch ratios were generated. RESULTS: Of 410 consecutive patients who underwent CTP for suspected stroke, 60 (15%) had acute anterior circulation LVO. Of these, 26 (43%) had Tmax > 6 seconds abnormalities discordant with clinical symptoms and vessel imaging. There was strong interrater agreement on artifact volume (r2 = 0.927). Among patients with discordant Tmax imaging, the median artifactual volume was 12cc (IQR 3-21cc), accounting for a median of 8% of the automated Tmax > 6 seconds volume (IQR 3-16%, range 1-64%). Recalculation of the Tmax > 6 seconds volume resulted in 1 patient being reclassified as having an "unfavorable" mismatch ratio (2.04-1.40). CONCLUSION: Nearly half of patients had evidence of artifactual penumbral imaging on automated CTP, which rarely lead to misclassification of thrombectomy eligibility. Although artifactual findings are reliably identified by trained raters, our results emphasize the need to evaluate CTP results with knowledge of the patient's clinical symptoms and vascular imaging.

Prevalence and Temporal Distribution of Fast and Slow Progressors of Infarct Growth in Large Vessel Occlusion Stroke.

Background and Purpose- Fast and slow progressors of infarct growth due to anterior circulation large vessel occlusion are commonly observed in clinical practice. We aimed to estimate the prevalence and temporal distribution of fast and slow progressors among anterior circulation large vessel occlusion patients diagnosed within 24 hours of stroke onset. Methods- Single-center retrospective study of all patients with anterior circulation large vessel occlusion who underwent baseline computed tomographic perfusion or magnetic resonance imaging within 24 hours of stroke onset. Prevalence was determined for fast progressors (ischemic core >70 mL, <6 hours of stroke onset) and slow progressors (ischemic core ≤30 mL, >6-24 hours of stroke onset). Results- One hundred eighty-five patients were included. The median time interval from stroke onset to baseline core imaging was 7.6 hours (interquartile range, 3.9-13.2), and median core volume was 17 mL (range, 0-405). Patients had core volume ≤70 mL in 72% of cases in the overall cohort. The prevalence of fast progressors was 25% (95% CI, 17%-37%) and reached 40% (95% CI, 24%-59%) between 3 and 4.5 hours after stroke onset. The prevalence of slow progressors was 55% (95% CI, 46%-64%) and was similar across time intervals beyond 6 hours after stroke onset. Conclusions- Most anterior circulation large vessel occlusion patients had small-to-moderate ischemic core volume, irrespective of early or delayed presentation within 24 hours of stroke onset. Fast progressors were highly prevalent between 3 and 4.5 hours after stroke onset.

Role of low dose 256-slice CT perfusion imaging in predicting mediastinal lymph node metastasis of lung cancer

SUMMARY OBJECTIVE: CT perfusion (CTP) is an imaging technique that can be used to evaluate the changes in the microcirculation of tumor tissues. Our study aimed to investigate the role of CTP in predicting mediastinal lymph node metastasis. METHODS: Clinical data of 58 patients who received surgical resection of lung cancer and lymph node dissection in our hospital from June 2012 to December 2014 were collected. Patients were divided into a positive lymph node metastasis group and a negative lymph node metastasis group. Parameters of CTP, including peak enhancement intensity (PEI), perfusion value (PV), as well as blood volume (BV), were compared between the two groups. The receiver-operating characteristic (ROC) curve was used to predict mediastinal lymph node metastasis. RESULTS: The PV of the positive lymph node metastasis group was significantly higher than that of the negative group (p < 0.001). The ROC curve analysis showed that PV can be used as an index to predict mediastinal lymph node metastasis of lung cancer. The sensitivity and specificity of a PV greater than 7.5ml·min-1·ml-1 in predicting lymph node metastasis of lung cancer were 78.3 % and 91.4 %, respectively. CONCLUSION: The PV of low dose CT perfusion can be used as an index for predicting mediastinal lymph node metastasis of lung cancer.

RESUMO OBJETIVOS: A perfusão por TC objetiva (CTP) é uma técnica de imagem que pode ser usada para avaliar as alterações na microcirculação de tecidos tumorais. Nosso estudo teve como objetivo investigar o papel da CTP na predição de metástases em linfonodos mediastinais. MÉTODOS: Dados clínicos de 58 pacientes que receberam ressecção cirúrgica de câncer de pulmão e dissecção de linfonodos em nosso hospital de junho de 2012 a dezembro de 2014 foram coletados. Os pacientes foram divididos em grupo positivo para metástase linfonodal e grupo negativo para metástase linfonodal. Parâmetros de CTP incluindo pico de intensidade de realce (PEI) e valor de perfusão (PV), bem como volume de sangue (BV), foram comparados entre os dois grupos. A curva característica de operação do receptor (ROC) foi usada para predizer metástase linfonodal mediastinal. RESULTADOS: PV do grupo de linfonodos metastáticos positivos foi significativamente maior do que o grupo negativo de linfonodos metastáticos (p<0,001). A análise da curva ROC mostrou que a PV pode ser usada como um índice para predizer a metástase linfonodal mediastinal do câncer de pulmão. A sensibilidade e a especificidade da VP maior que 7,5ml · min-1 · ml-1 na predição de metástase linfonodal de câncer de pulmão foram de 78,3% e 91,4%, respectivamente. CONCLUSÃO: A VP de perfusão por TC de baixa dose pode ser usada como um índice para a predição de metástase linfonodal mediastinal de câncer de pulmão.

Intra- and interobserver reproducibility of pancreatic perfusion by computed tomography.

The aim of this study was to measure intra- and interobserver agreement among radiologists in the assessment of pancreatic perfusion by computed tomography (CT). Thirty-nine perfusion CT scans were analyzed. The following parameters were measured by three readers: blood flow (BF), blood volume (BV), mean transit time (MTT) and time to peak (TTP). Statistical analysis was performed using the Bland-Altman method, linear mixed model analysis, and intraclass correlation coefficient (ICC). There was no significant intraobserver variability for the readers regarding BF, BV or TTP. There were session effects for BF in the pancreatic body and MTT in the pancreatic tail and whole pancreas. There were reader effects for BV in the pancreatic head, pancreatic body and whole pancreas. There were no effects for the interaction between session and reader for any perfusion parameter. ICCs showed substantial agreement for the interobserver measurements and moderate to substantial agreement for the intraobserver measurements, with the exception of MTT. In conclusion, satisfactory reproducibility of measurements was observed for TTP in all pancreatic regions, for BF in the head and BV in the tail, and these parameters seem to ensure a reasonable estimation of pancreatic perfusion.