RESUMEN
Cerebral microbleeds (CMBs) are a recognised biomarker of traumatic axonal injury (TAI). Their number and location provide valuable information in the long-term prognosis of patients who sustained a traumatic brain injury (TBI). Accurate detection of CMBs is necessary for both research and clinical applications. CMBs appear as small hypointense lesions on susceptibility-weighted magnetic resonance imaging (SWI). Their size and shape vary markedly in cases of TBI. Manual annotation of CMBs is a difficult, error-prone, and time-consuming task. Several studies addressed the detection of CMBs in other neuropathologies with convolutional neural networks (CNNs). In this study, we developed and contrasted a classification (Patch-CNN) and two segmentation (Segmentation-CNN, U-Net) approaches for the detection of CMBs in TBI cases. The models were trained using 45 datasets, and the best models were chosen according to 16 validation sets. Finally, the models were evaluated on 10 TBI and healthy control cases, respectively. Our three models outperform the current status quo in the detection of traumatic CMBs, achieving higher sensitivity at low false positive (FP) counts. Furthermore, using a segmentation approach allows for better precision. The best model, the U-Net, achieves a detection rate of 90% at FP counts of 17.1 in TBI patients and 3.4 in healthy controls.
Asunto(s)
Lesiones Traumáticas del Encéfalo , Hemorragia Cerebral , Lesiones Traumáticas del Encéfalo/complicaciones , Lesiones Traumáticas del Encéfalo/diagnóstico por imagen , Hemorragia Cerebral/diagnóstico por imagen , Hemorragia Cerebral/patología , Humanos , Imagen por Resonancia Magnética , Redes Neurales de la ComputaciónRESUMEN
BACKGROUND AND PURPOSE: In the chronic phase after traumatic brain injury, DTI findings reflect WM integrity. DTI interpretation in the subacute phase is less straightforward. Microbleed evaluation with SWI is straightforward in both phases. We evaluated whether the microbleed concentration in the subacute phase is associated with the integrity of normal-appearing WM in the chronic phase. MATERIALS AND METHODS: Sixty of 211 consecutive patients 18 years of age or older admitted to our emergency department ≤24 hours after moderate to severe traumatic brain injury matched the selection criteria. Standardized 3T SWI, DTI, and T1WI were obtained 3 and 26 weeks after traumatic brain injury in 31 patients and 24 healthy volunteers. At baseline, microbleed concentrations were calculated. At follow-up, mean diffusivity (MD) was calculated in the normal-appearing WM in reference to the healthy volunteers (MDz). Through linear regression, we evaluated the relation between microbleed concentration and MDz in predefined structures. RESULTS: In the cerebral hemispheres, MDz at follow-up was independently associated with the microbleed concentration at baseline (left: B = 38.4 [95% CI 7.5-69.3], P = .017; right: B = 26.3 [95% CI 5.7-47.0], P = .014). No such relation was demonstrated in the central brain. MDz in the corpus callosum was independently associated with the microbleed concentration in the structures connected by WM tracts running through the corpus callosum (B = 20.0 [95% CI 24.8-75.2], P < .000). MDz in the central brain was independently associated with the microbleed concentration in the cerebral hemispheres (B = 25.7 [95% CI 3.9-47.5], P = .023). CONCLUSIONS: SWI-assessed microbleeds in the subacute phase are associated with DTI-based WM integrity in the chronic phase. These associations are found both within regions and between functionally connected regions.
Asunto(s)
Lesiones Traumáticas del Encéfalo/diagnóstico por imagen , Hemorragia Cerebral/diagnóstico por imagen , Sustancia Blanca/diagnóstico por imagen , Enfermedad Aguda , Adulto , Enfermedad Crónica , Cuerpo Calloso/diagnóstico por imagen , Imagen de Difusión por Resonancia Magnética , Imagen de Difusión Tensora , Servicios Médicos de Urgencia , Femenino , Voluntarios Sanos , Humanos , Masculino , Valor Predictivo de las Pruebas , Pronóstico , Estudios RetrospectivosRESUMEN
In this paper a Computer Aided Detection (CAD) system is presented to automatically detect Cerebral Microbleeds (CMBs) in patients with Traumatic Brain Injury (TBI). It is believed that the presence of CMBs has clinical prognostic value in TBI patients. To study the contribution of CMBs in patient outcome, accurate detection of CMBs is required. Manual detection of CMBs in TBI patients is a time consuming task that is prone to errors, because CMBs are easily overlooked and are difficult to distinguish from blood vessels. This study included 33 TBI patients. Because of the laborious nature of manually annotating CMBs, only one trained expert manually annotated the CMBs in all 33 patients. A subset of ten TBI patients was annotated by six experts. Our CAD system makes use of both Susceptibility Weighted Imaging (SWI) and T1 weighted magnetic resonance images to detect CMBs. After pre-processing these images, a two-step approach was used for automated detection of CMBs. In the first step, each voxel was characterized by twelve features based on the dark and spherical nature of CMBs and a random forest classifier was used to identify CMB candidate locations. In the second step, segmentations were made from each identified candidate location. Subsequently an object-based classifier was used to remove false positive detections of the voxel classifier, by considering seven object-based features that discriminate between spherical objects (CMBs) and elongated objects (blood vessels). A guided user interface was designed for fast evaluation of the CAD system result. During this process, an expert checked each CMB detected by the CAD system. A Fleiss' kappa value of only 0.24 showed that the inter-observer variability for the TBI patients in this study was very large. An expert using the guided user interface reached an average sensitivity of 93%, which was significantly higher (p = 0.03) than the average sensitivity of 77% (sd 12.4%) that the six experts manually detected. Furthermore, with the use of this CAD system the reading time was substantially reduced from one hour to 13 minutes per patient, because the CAD system only detects on average 25.9 false positives per TBI patient, resulting in 0.29 false positives per definite CMB finding.
Asunto(s)
Hemorragia Encefálica Traumática/diagnóstico por imagen , Hemorragia Cerebral/diagnóstico por imagen , Interpretación de Imagen Asistida por Computador/métodos , Reconocimiento de Normas Patrones Automatizadas/métodos , Adulto , Hemorragia Encefálica Traumática/complicaciones , Hemorragia Cerebral/complicaciones , Hemorragia Cerebral/patología , Femenino , Humanos , Imagen por Resonancia Magnética , MasculinoRESUMEN
CONTEXT: Increased bone fragility is a frequent complication of hypercortisolism due predominantly to suppression of bone formation. Sclerostin is an osteocyte-produced negative regulator of bone formation, which is up-regulated by glucocorticoids in mice. OBJECTIVE: Our objective was to assess the effect of endogenous hypercortisolism on circulating sclerostin and bone turnover in humans. DESIGN: We measured sclerostin, ß-C-terminal telopeptide, amino-terminal propeptide of type 1 procollagen, and fibroblast growth factor 23 in blood samples of 21 patients with endogenous hypercortisolism and 21 age- and gender-matched controls. In 12 patients, measurements were repeated at various time intervals after successful surgical treatment (transsphenoidal surgery or adrenalectomy). RESULTS: Plasma sclerostin levels were significantly decreased in patients compared with controls (112±49 vs. 207±48 pg/ml, P<0.001). In the 12 patients who were evaluated after surgical treatment, sclerostin levels increased from 121.4±46.5 to 175.8±78.5 pg/ml (P=0.003). These changes in plasma sclerostin levels were accompanied by significant increases in levels of fibroblast growth factor 23 (from 44.2±12.2 to 84.0±58.8 pg/ml, P=0.017) and of the bone turnover markers amino-terminal propeptide of type 1 procollagen (from 31.7±18.2 to 94.2±92.2 ng/ml, P=0.037) and ß-C-terminal telopeptide (from 134.2±44 to 409.2±285 pg/ml, P=0.005). CONCLUSIONS: Contrary to the findings in mice, circulating sclerostin is decreased in patients with chronic endogenous hypercortisolism and increases after treatment. These findings suggest that in humans, chronic exposure to glucocorticoids affects the number or function of osteocytes rather than the production of sclerostin.
Asunto(s)
Proteínas Morfogenéticas Óseas/sangre , Remodelación Ósea/fisiología , Síndrome de Cushing/metabolismo , Síndrome de Cushing/cirugía , Proteínas Adaptadoras Transductoras de Señales , Adrenalectomía , Adulto , Animales , Colágeno Tipo I/sangre , Femenino , Factor-23 de Crecimiento de Fibroblastos , Factores de Crecimiento de Fibroblastos/sangre , Marcadores Genéticos , Humanos , Hidrocortisona/sangre , Masculino , Ratones , Persona de Mediana Edad , Osteocitos/fisiología , Fragmentos de Péptidos/sangre , Péptidos/sangre , Procolágeno/sangreRESUMEN
BACKGROUND: Patients with Cushing's syndrome have a high prevalence of osteoporotic fractures. Little is known about factors determining bone mineral density (BMD) in these patients. OBJECTIVE: To evaluate which factors influence BMD at the time of diagnosis of Cushing's syndrome. METHODS: In 77 consecutive patients with Cushing's syndrome with a median age of 41.1 (interquartile range 31.1 to 52.2) years we measured BMD of the lumbar spine and the femoral neck at the time of diagnosis. From the medical records we obtained information on possible predictors of BMD. We compared BMD with a reference population by means of the Z score. Adjustment for other variables than age and sex was made with linear regression models. RESULTS: Patients with Cushing's syndrome had a low Z score in both the lumbar spine (-1.07 SD (95% CI -1.43 to -0.71 SD )) and in the femoral neck (-0.81 SD (95% CI -1.06 to -0.55 SD )). 82% of patients had osteopenia at one or both sites (T score lower than -1 SD ), including 31% with osteoporosis (T score -2.5 SD or lower). The main determinant of the Z score at both sites and for both sexes was age. Z score increased by about 0.4 SD per decade. 81% of patients.