Use of Apparent Diffusion Coefficient Values for Diagnosis of Pediatric Posterior Fossa Tumors

Abstract

We prospectively compared the ability of neuroradiologists to diagnose medulloblastoma with novice raters using only apparent diffusion coefficient (ADC) values measured on ADC maps. One hundred and three pediatric patients with pre-operative magnetic resonance imaging scans showing a posterior fossa tumor with histological verification were retrospectively identified from a ten-year period at a tertiary care medical center. A single observer measured the lowest ADC values in all tumors to determine the mean minimum ADC (ADCmin) value that provided greatest accuracy in distinguishing medulloblastomas from other tumors, which was determined to be 0.66×10(-3) mm(2)/s. Imaging studies, including ADC maps, from 90 patients were provided to two neuroradiologists, who provided a diagnosis, which was later dichotomized as medulloblastoma or other. Two medical students measured ADCmin within tumors and those with ADCmin < 0.66×10(-3) mm(2)/s were recorded as medulloblastoma; any other value was recorded as other. Diagnostic accuracy was measured. ADCmin values allowed a correct identification of lesions as either medulloblastoma or other in 91% of cases. After diagnoses by the two neuroradiologists were categorized as either medulloblastoma or other, their diagnoses were correct in 90% and 84% of cases, respectively. In 19 cases, at least one neuroradiologist was incorrect; the addition of ADC values to clinical interpretation would have allowed a correct diagnosis in 63% of such cases. Diagnostic accuracy based on ADC values by medical students was comparable to that of subspecialty-trained neuroradiologists. Our findings suggest that the addition of ADC values to standard film interpretation may improve the diagnostic rate for these tumors.

Current Clinical Brain Tumor Imaging

“…46–48 Because of the heterogeneous nature of intracranial tumors, particularly gliomas, histogram analysis can be employed to better assess ADC metrics. 43,49–51 Although some authors have demonstrated good correlation between cell density and ADC values based on stereotactic biopsy, the required postprocessing and overlap in ADC values between tumor grades limit the role of quantitative ADC in clinical practice.…”

Case-based review: ependymomas in adults

“…Restricted diffusion may be present in highly cellular solid regions of tumor, though typically apparent diffusion coefficients in ependymoma are not as low as in medulloblastoma. 4,6 An example of a posterior fossa ependymoma in an adult is shown in Figure 3.…”

Utilidad del coeficiente de difusión aparente en resonancia magnética como método auxiliar para la diferenciación entre meduloblastomas y ependimomas de la fosa craneal posterior en niños y adultos tratados en el Hospital Carlos Van Buren de Valparaíso: Una experiencia preliminar

“…Ambas lesiones pueden presentarse en línea media, tener componentes sólidos y quísticos, y presentarse alrededor de los cinco años de edad. Sin embargo, poseen algunas características morfológicas que pueden ayudar a distinguirlos 13,14 . Imagenológicamente el meduloblastoma es hiperdenso en la TC, con estructura heterogénea en RM, hipointenso en secuencias ponderadas en T1, e iso o discretamente hiperintenso en secuencias T2, con calcificaciones en 10-20% y un componente necrótico o cistoídeo en el 50% de los casos.…”

“…La DWI por RM ha demostrado utilidad en la diferenciación de estos tumores mediante la comparación de los valores de coeficiente de difusión aparente (ADC) intratumorales 1,[12][13][14]17 . En diversos estudios se ha demostrado que el meduloblastoma posee valores de ADC más bajos que los del ependimoma 10 .…”