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PURPOSE: To evaluate the accuracy of retrospective rigid image registration and fusion between F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and magnetic resonance imaging (MRI) of the upper abdomen. PATIENTS, MATERIAL, METHODS: Image fusion of PET and MRI was performed in 30 patients with suspected malignancy of the liver or pancreas. Using a commercially available image fusion tool capable of rigid manual point-based registration, PET-Images were retrospectively registered and fused by matching eight homologous points in the 3D spoiled gradient echo (GRE) MRI sequences acquired in portal venous phase and in the CT-component of PET/CT. Two separate observers (R1, R2) assessed accuracy of image registration by determining the distances in the x-, y- and z-axis as well as the absolute distance between anatomical landmarks which differed from the landmarks chosen for registration. Quality of fusion was graded using a three point grading scale (1 poorly fused; 2 satisfactory fused; 3 correctly fused) and compared to hybrid PET/CT fusion. RESULTS: Mean time of registration per patient was less than 2 minutes. Objective registration assessment showed errors between 2.4-6.3 mm in x-axis: mean 3.6 mm (R1); 4.6 mm (R2), 2.3-9.3 mm in y-axis (mean 5.1 mm; 5.5 mm) and 3.3-12.0 mm in z-axis (mean 5.9 mm; 5.9 mm.) The mean error in absolute distance between points was 6.0-16.8 mm (mean 9.9 mm; 10.6 mm). In visual assessment, most fusions were graded to be satisfactory or correctly fused: R1, R2: grade 3, 11/30 (36.7%), 22/30 (73.3%); grade 2, 13/30 (43.3%), 8/30 (26.7%); grade 1, 6/30 (20%), 0/30 (0%). Fusions were mostly comparable to hybrid PET/CT fusions. All of the fusions were defined as diagnostically relevant by both observers. CONCLUSION: Retrospective rigid image fusion of FDG-PET and MRI of the upper abdomen using the CT-component of PET/CT for registration is feasible without adaptation in image acquisition protocols and shows sub-centimeter registration errors in most cases.
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Fluorodesoxiglucosa F18 , Neoplasias Hepáticas/diagnóstico por imagen , Neoplasias Pancreáticas/diagnóstico por imagen , Adulto , Anciano , Anciano de 80 o más Años , Tamaño Corporal , Neoplasias del Colon/diagnóstico por imagen , Neoplasias del Colon/secundario , Femenino , Humanos , Hígado/anatomía & histología , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Variaciones Dependientes del Observador , Tomografía de Emisión de Positrones/métodos , Tomografía Computarizada por Rayos X/métodosRESUMEN
AIM: To assess whether a simple. diameter-based formula applicable to cross-sectional images can be used to calculate the total liver volume. MATERIALS AND METHODS: On 119 cross-sectional examinations (62 computed tomography and 57 magnetic resonance imaging) a simple, formula-based method to approximate the liver volume was evaluated. The total liver volume was approximated measuring the largest craniocaudal (cc), ventrodorsal (vd), and coronal (cor) diameters by two readers and implementing the equation: Vol(estimated)=cc x vd x cor x 0.31. Inter-rater reliability, agreement, and correlation between liver volume calculation and virtual liver volumetry were analysed. RESULTS: No significant disagreement between the two readers was found. The formula correlated significantly with the volumetric data (r>0.85, p<0.0001). In 81% of cases the error of the approximated volume was <10% and in 92% of cases <15% compared to the volumetric data. CONCLUSION: Total liver volume can be accurately estimated on cross-sectional images using a simple, diameter-based equation.
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Antropometría/métodos , Hígado/anatomía & histología , Adulto , Anciano , Algoritmos , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Imagenología Tridimensional/métodos , Hígado/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Tamaño de los Órganos , Tomografía Computarizada por Rayos X/métodos , Adulto JovenRESUMEN
Treatment of pelvic and acetabular fractures still poses a major challenge to trauma surgeons. We present a tool for intervention planning for such injuries using patient-specific models built from Computed Tomography data. The presented tool has three main parts: (1) the virtual reduction of the bone fragments, (2) the virtual adaptation of the osteosynthesis implants and (3) Finite Element Analysis (FEA) for testing mechanical behavior of the resulting intervention plan. Our tool provides an intuitive visuo-hapic interface designed to be used by trauma surgeons. The type and size of the osteosynthesis material can be determined and measurements like distances and angles relative to landmarks can be taken. First results of prospectively planned interventions show an excellent correlation and a significant gain in operation time.
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Fracturas Óseas/cirugía , Huesos Pélvicos/lesiones , Tacto , Interfaz Usuario-Computador , Simulación por Computador , Humanos , Imagenología Tridimensional , Ortopedia/métodos , SuizaRESUMEN
We report the case of a 57-year-old female who developed a large pseudoaneurysm of the right circumflex iliac artery 15 months after renal transplantation. Minimal invasive treatment was successfully performed with ultrasound-guided thrombin injection using the B-flow mode.