Objetivo: describir los hallazgos de imagen clave en los estudios de RM estructural de las demen- cias de origen neurodegenerativo más frecuentes: enfermedad de Alzheimer, demencia vascular, demencia de cuerpos de Lewy, variantes de la demencia frontotemporal, parálisis supranu- clear progresiva, variantes de la atrofia multisistémica, parkinson-demencia y degeneración corticobasal.
Conclusión: El papel de la resonancia magnética hoy en día ya no está limitado a excluir causas subyacentes de deterioro cognitivo, sino que puede mostrar patrones de atrofia y otros datos con un alto valor predictivo para determinadas demencias que, aunque no son específicos ni únicos de cada patología, pueden ayudar a confirmar una sospecha diagnóstica o a identificar inicios tempranos de determinados procesos. Por ello es importante que los radiólogos conozcan los hallazgos típicos de las demencias más frecuentes.

Palabras clave: Resonancia magnética; Atrofia; Demencia; Enfermedad de Alzheimer; Parálisis supranuclear progresiva; Demencia vascular; Atrofia multisistémica; Enfermedad de Parkinson; Demencia frontotemporal

Background:
Several US risk stratification schemas for assessing adnexal lesions exist. These multiple-subcategory systems may be more multifaceted than necessary for isolated adnexal lesions in average-risk women.

Purpose:
To explore whether a US-based classification scheme of classic versus nonclassic appearance can be used to help appropriately triage women at average risk of ovarian cancer without compromising diagnostic performance.

Materials and Methods:
This retrospective multicenter study included isolated ovarian lesions identified at pelvic US performed between January 2011 and June 2014, reviewed between September 2019 and September 2020. Lesions were considered isolated in the absence of ascites or peritoneal implants. Lesions were classified as classic or nonclassic based on sonographic appearance. Classic lesions included simple cysts, hemorrhagic cysts, endometriomas, and dermoids. Otherwise, lesions were considered nonclassic. Outcomes based on histopathologic results or clinical or imaging follow-up were recorded. Diagnostic performance and frequency of malignancy were calculated. Frequency of malignancy between age groups was compared using the x2 test, and Poisson regression was used to explore relationships between imaging features and malignancy.

Results:
A total of 970 isolated lesions in 878 women (mean age, 42 years 6 14 [SD]) were included. The malignancy rate for classic lesions was less than 1%. Of 970 lesions, 53 (6%) were malignant. The malignancy rate for nonclassic lesions was 32% (33 of 103) when blood flow was present and 8% (16 of 194) without blood flow (P , .001). For women older than 60 years, the malignancy rate was 50% (10 of 20 lesions) when blood flow was present and 13% (five of 38) without blood flow (P = .004). The sensitivity, specificity, positive predictive value, and negative predictive value of the classic-versus-nonclassic schema was 93% (49 of 53 lesions), 73% (669 of 917 lesions), 17% (49 of 297 lesions), and 99% (669 of 673 lesions), respectively, for detection of malignancy.

Conclusion:
Using a US classification schema of classic- or nonclassic-appearing adnexal lesions resulted in high sensitivity and specificity in the diagnosis of malignancy in ovarian cancer. The highest risk of cancer was in isolated nonclassic lesions with blood flow in women older than 60 years.