R. Sopena

99mTc-hexamethylpropylene amineoxime leukocyte scintigraphy in acute pancreatitis : An alternative to contrast-enhanced computed tomography?

OBJECTIVES:Contrast-enhanced computed tomography (CECT) is the most efficient imaging technique for the diagnosis and staging of acute pancreatitis (AP); its use, however, may be unfeasible in some patients as a consequence of the drawbacks of intravenous (IV) contrast material. The aim of this study was to test the utility of labeled leukocyte scintigraphy (LLS) as an alternative imaging technique to CECT for the staging of AP.METHODS:Sixty-six patients with AP were prospectively studied. All patients underwent CECT and pancreatic LLS using 99mTc-hexamethylpropylene amineoxime as leukocyte label within a time interval of 2 days, in the early phase of AP. In addition, all patients had their serum C-reactive protein (CRP) concentration measured within 48–72 h after admission. CECT images were analyzed for Balthazars grade of pancreatitis and for the presence or absence of pancreatic necrosis. Scintigraphic activity of 3–4 h planar images was scored on a 0–2 scale in relation to physiological liver uptake.RESULTS:LLS score was significantly related (p < 0.001) to both components of CECT (grade of pancreatitis and pancreatic necrosis). LLS and serum CRP showed similar results for detecting the most severe pancreatic damage as showed by their respective receiver operating characteristic (ROC) curves. Sensitivities and specificities of LLS score of 2 were, respectively, 62% and 96% for the detection of grade D-E pancreatitis and 90% and 89% for the detection of pancreatic necrosis. Scintigraphic score of 2 increased the likelihood of grade D-E pancreatitis from 32% (pretest probability) to 87% (posttest probability) (likelihood ratio: 13.9) and that of pancreatic necrosis from 16% to 60% (likelihood ratio: 8.4).CONCLUSION:Our results show that leukocytes are related to the severity of local pancreatic damage in AP. Thus, LLS is a potential alternative technique to CECT for staging AP.

Utilidad de la PET con FDG en la valoración del paciente con traumatismo craneoencefálico severo crónico

Resumen Objetivo Describir los cambios del metabolismo glucolitico cerebral tras un traumatismo craneoencefalico (TCE) severo en el momento de iniciar la rehabilitacion, medir su nivel de acuerdo diagnostico con las tecnicas de neuroimagen morfologica (RM/TC) y correlacionar los hallazgos en neuroimagen con la intensidad del TCE sufrido y con la discapacidad funcional para las actividades de la vida diaria. Material y metodos Estudio prospectivo de 55 pacientes con antecedente de TCE severo (GCS ≤ 8) mediante 18F-FDG PET y RM/TC. Medida del acuerdo entre los estudios de neuroimagen anatomica y funcional. Valoracion funcional mediante el test de Barthel-M y calculo de correlacion entre la afectacion cerebral en neuroimagen y el test de Barthel y la GCS. Resultados El 100 % de los pacientes presento alteracion en el metabolismo cerebral, siendo los talamos las areas mas frecuentemente afectadas. El 60 % de los pacientes mostro lesiones en RM/TC, mas frecuentemente frontales. El grado de acuerdo para el diagnostico de patologia entre la neuroimagen morfologica y funcional fue muy bajo. La intensidad del traumatismo sufrido y el nivel de discapacidad se correlacionaron de forma estadisticamente significativa con el grado de afectacion del metabolismo cerebral. Conclusiones La PET con 18F-FDG permite conocer el estado del metabolismo glucolitico cerebral en el momento de iniciar la rehabilitacion, correlacionandose con la severidad del traumatismo sufrido y con la discapacidad para las actividades de la vida diaria. La PET diagnostica mayor numero de lesiones que la neuroimagen anatomica y demuestra una elevada vulnerabilidad talamica, con lesiones hasta en el 76% de pacientes con antecedente de TCE severo.

[Thalamic metabolism and neurological outcome after traumatic brain injury. A voxel-based morphometric FDG-PET study].

OBJECTIVE to study the relationship between thalamic metabolism and neurological outcome in patients who had sustained a traumatic brain injury (TBI). METHODS nineteen patients who had sustained a severe TBI and ten control subjects were included in this study. Six of the 19 patients had a low level of consciousness (vegetative state or minimally conscious state), while thirteen showed normal consciousness. All patients underwent a PET with 18F-FDG, 459.4 +/- 470.9 days after the TBI. The FDG-PET images were normalized in intensity, with a metabolic template being created from data derived from all subjects. The thalamic trace was generated automatically with a mask of the region of interest in order to evaluate its metabolism. A comparison between the two groups was carried out by a two sample voxel-based T-test, under the General Linear Model (GLM) framework. RESULTS patients with low consciousness had lower thalamic metabolism (MNI-Talairach coordinates: 12, -24, 18; T = 4.1) than patients with adequate awareness (14, -28, 6; T = 5.5). Control subjects showed the greatest thalamic metabolism compared to both patients groups. These differences in metabolism were more pronounced in the internal regions of the thalamus. CONCLUSIONS the applied method may be a useful ancillary tool to assess neurological outcomes after a TBI, since it permits an objective quantitative assessment of metabolic function for groups of subjects. Our results confirm the vulnerability of the thalamus to suffering the effects of the acceleration-deceleration forces generated during a TBI. It is hypothesized that patients with low thalamic metabolism represent a subset of subjects highly vulnerable to neurological and functional disability after TBI.

Metabolismo talámico y situación neurológica tras un traumatismo craneoencefálico. Estudio mediante PET-FDG y morfometría basada en vóxel

Objetivos: Estudiar la relacion entre el metabolismo talamico y la situacion neurologica en pacientes que han sufrido un traumatismo craneoencefalico (TCE). Material y metodos: Se incluyo a 19 pacientes que habian sufrido un TCE grave y 10 sujetos control. De los 19 pacientes, 6 presentaban un grado de alerta bajo (estado vegetativo o estado de minima conciencia), mientras que 13 mostraban un grado de alerta normal. A todos los pacientes se les realizo una tomografia con emision de positrones (PET) con 18-fluorodesoxiglucosa (18F-FDG) 459,4 ± 470,9 dias despues del TCE. Las imagenes de PET-FDG se normalizaron en intensidad, creandose posteriormente una plantilla metabolica del grupo entre todos los sujetos. El trazado talamico se genero automaticamente con una mascara de la region de interes. Se comparo el metabolismo talamico de los dos grupos de pacientes respecto al grupo control, para ello se utilizo un metodo de analisis basado en voxel, con significacion estadistica, p < 0,05 corregido para multiples comparaciones. Resultados: Los pacientes con grado de alerta bajo mostraron menor metabolismo talamico (coordenadas MNI-Talairach, 12, -24, 18; T = 4,1), con respecto a los sujetos control, que los pacientes con grado de alerta adecuado (14, -28, 6; T = 5,5). Estas diferencias en el metabolismo fueron mas acentuadas en las regiones internas del talamo. Conclusiones: La PET-FDG puede ser una herramienta util para valorar la situacion neurologica despues de un TCE. El metodo utilizado permite una evaluacion objetiva y cuantitativa de imagenes de PET-FDG para grupos de sujetos. Nuestros resultados confirman la vulnerabilidad del talamo a sufrir los efectos de las fuerzas de aceleracion-desaceleracion generadas durante un TCE.

Usefulness of Technetium-99m Hexamethylpropylene Amine Oxime-Labeled Leukocyte Scintigraphy to Detect Pancreatic Necrosis in Patients with Acute Pancreatitis

Background: In acute pancreatitis (AP), pancreatic necrosis (PN) is an important local complication that can be identified by means of contrast-enhanced computed tomography (CECT). Pancreatic leukocyte infiltration is a significant pathogenic event in the development of PN that can be detected by labeled leukocyte scintigraphy (LLS). The aim of this study was to evaluate the utility of LLS with technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) to detect the presence of PN in patients with AP. Methods: Prospective cohort study of 84 patients with AP. Patients underwent LLS and the activity of images was scored on a 0–3 scale. CETC was performed to assess PN. Ranson, Glasgow and APACHE-II scores were calculated. Serum C-reactive protein (CRP) was measured. Sensitivity (Sn), specificity (Sp), positive predictive values (PPV), negative predictive values (NPV), areas under receiver operating characteristic (ROC) curves, likelihood ratios, odds ratios, analysis of variances between groups and correlation coefficients between tests were calculated. Results: PN was present in 11 (13%) patients. Pancreatic labeled leukocyte uptake was present in 38 patients (45%). Sn, Sp, PPV and NPV of LLS grade 2–3 for PN diagnosis were the highest (91, 88, 53 and 98%, respectively) of all tests. Patients with LLS grade 2–3 were 71 times more likely to be at risk of PN compared to those with LLS grade 0–1. The area under ROC curve of the LLS was the largest. A significant correlation was obtained between LLS and CRP (p < 0.001). Conclusion: In patients with AP, LLS with 99mTc-HMPAO detects PN with an acceptable level of confidence and therefore could be considered an alternative technique to CECT in detecting PN.