Diagnostic approach in suspected recurrent primary brain tumors using (18)FDG-PET/MRI, perfusion MRI, visual and quantitative analysis, and three dimensional stereotactic surface projections. First experience in Mexico.

UNLABELLED: Thirty patients with primary cerebral tumors WHO III and IV previously treated, undergoing evaluation for tumoral recurrence, they underwent (18)FDG-PET study, MRI and PMRI. PET uptake was determined by visual inspection and was quantified by use of standard uptake values, the ratio of tumor uptake to normal tissue and were z scored using automated voxel-based comparison. PMRI was quantified by use of ratios of cerebral blood volume (rCBV). The accuracies were determined by comparing imaging data with histologic findings and clinical follow up of up to 21 mo. RESULTS: Sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV) and accuracy were 100 %, 82 %, 90 %, 100 % and 93 % respectively for the PET/MRI fusion and 68 %, 82 %, 87 %, 60 % and 73 % respectively for PMRI. There were two false positive cases for PET/MRI fusion that were confirmed by biopsy: chronic inflammation; and foreign body granulomas. The receiver operating characteristic (ROC) curve analysis showed statistically significant difference (p = 0.0225). CONCLUSIONS: (18)FDG SUVs, glucose uptake ratios and 3D stereotactic surface projections in brain tumors were not a reliable measure for evaluating recurrent tumors. PET/MRI fusion was more sensitive and accurate than PMRI for imaging recurrent primary brain tumors. The region of interest can be visually analyzed on the PET/MRI fusion images and described as recurrent tumor when any activity (lower, equal or greater than the contralateral cortex) is presented in the zone of hyperintensity seen on the post-gadolinium T1-weighted MRI.

Diagnostic approach in suspected recurrent primary brain tumors using 18FDG-PET/MRI, perfusion MRI, visual and quantitative analysis, and three dimensional stereotactic surface projections. First experience in Mexico / Enfoque diagnóstico en pacientes con sospecha de tumor cerebral primario recurrente utilizando 18fdg-pet/rm, rm de perfusión, análisis visual y cuantitativo y proyecciones estereotáxicas de superficie tridimensionales. Primera experiencia en México

Thirty patients with primary cerebral tumors WHO III and IV previously treated, undergoing evaluation for tumoral recurrence, they underwent 18FDG-PET study, MRI and PMRI. PET uptake was determined by visual inspection and was quantified by use of standard uptake values, the ratio of tumor uptake to normal tissue and were z scored using automated voxel-based comparison. PMRI was quantified by use of ratios of cerebral blood volume (rCBV). The accuracies were determined by comparing imaging data with histologic findings and clinical follow up of up to 21 mo. Results. Sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV) and accuracy were 100 %, 82 %, 90 %, 100 % and 93 % respectively for the PET/MRI fusion and 68 %, 82 %, 87 %, 60 % and 73 % respectively for PMRI. There were two false positive cases for PET/MRI fusion that were confirmed by biopsy: chronic inflammation; and foreign body granulomas. The receiver operating characteristic (ROC) curve analysis showed statistically significant difference (p = 0.0225). Conclusions. 18FDG SUVs, glucose uptake ratios and 3D stereotactic surface projections in brain tumors were not a reliable measure for evaluating recurrent tumors. PET/MRI fusion was more sensitive and accurate than PMRI for imaging recurrent primary brain tumors. The region of interest can be visually analyzed on the PET/MRI fusion images and described as recurrent tumor when any activity (lower, equal or greater than the contralateral cortex) is presented in the zone of hyperintensity seen on the post-gadolinium T1-weighted MRI

Se ha hecho un estudio con 18FDG-PET, RM y perfusión por resonancia magnética en 30 pacientes con tumores cerebrales primarios grado OMS III y IV, previamente tratados y a los que se les iba a hacer el seguimiento de recurrencia tumoral. La captación de la PET estuvo determinada por la inspección visual y se cuantificó utilizando los valores de captación estándar, la proporción de captación tumoral/tejido normal y la desviación estándar z mediante comparación automatizada con vóxeles. La perfusión por resonancia magnética se cuantificó mediante la utilización de las proporciones del volumen sanguíneo cerebral. La exactitud diagnóstica se determinó comparando los datos de las imágenes con los hallazgos histológicos y el seguimiento clínico durante un período de hasta 21 meses. Resultados. La sensibilidad (Se), la especificidad (Sp), el valor predictivo positivo (VPP), el valor predictivo negativo (VPN) y la exactitud diagnóstica fueron del 100, 82, 90, 100 y 93 %, respectivamente, para la fusión PET/RM; y del 68, 82, 87, 60 y 73%, respectivamente, para la perfusión por resonancia magnética. Hubo dos casos falsos positivos para la fusión PET/RM que se confirmaron mediante biopsia: inflamación crónica y granulomas por cuerpo extraño. El análisis de las curvas características operativas del receptor (ROC) demostró una diferencia estadísticamente significativa (p = 0,0225). Conclusiones. Los valores de captación estandarizados de 18FDG (SUV), las proporciones de captación de glucosa y las proyecciones estereotáxicas de superficie en 3D (3D-SSP) de los tumores cerebrales no demostraron ser mediciones útiles para evaluar tumores recurrentes. La fusión PET/RM resultó ser más sensible y con mayor exactitud diagnóstica que la perfusión por resonancia magnética como diagnóstico de imagen de los tumores cerebrales primarios recurrentes. En las imágenes de fusión PET/RM puede analizarse la región de interés y reportarse como tumor recurrente cuando aparece cualquier actividad (menor, igual o mayor que en la corteza contralateral) en la zona de hiperintensidad observada en la RM con gadolinio y ponderada en T1