E4792. Diagnostic Challenges of Spontaneous Hyperdense CT Brain Lesions with Intrinsic T1W Hyperintensity on MRI, Beyond Hemorrhage
  1. Sean Teo; Sengkang General Hospital
  2. Aaron Chong; Sengkang General Hospital
  3. Chi Long Ho; Sengkang General Hospital
Intracranial spontaneous hyperdense lesions detected on noncontrast CT scans often raise concerns for hemorrhage. However, it is important to recognize that various other pathologies, both neoplastic and nonneoplastic, can result in hyperdensity on CT imaging. These hyperdense lesions can manifest as T1-weighted hyperintensities on MRI, adding complexity to the diagnostic process and requiring a comprehensive evaluation.

Educational Goals / Teaching Points
This pictorial review is based on an assessment of numerous CT brain scans within the Singaporean (Asian) demographic, aiming to identify and categorize at least seven different intracranial pathologies that exhibit hyperattenuation on noncontrast CT scans spontaneously. Through correlation with MRI and, when necessary, histopathology, this review emphasizes the need to consider a broader list of differential diagnoses beyond hemorrhage when interpreting hyperdense lesions on CT scans. By presenting various examples, we aim to enhance the understanding of CT hyperdense intracranial pathologies associated with T1-weighted hyperintensities on MRI.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Various examples of cases that have been selected for discussion include a colloid cyst, cavernoma, ranke cleft cyst, diabetic striatopathy, intra-axial melanoma, craniopharyngioma, white epidermoid cyst, and primary CNS lymphoma. Images selected will include CT and MRI images of the head and neck region (neuroradiology).

This case series serves as an educational resource, highlighting the diverse spectrum of differential diagnoses when encountering unenhanced intracranial hyperdense lesions on CT scans. These cases are associated with intrinsic T1 hyperintensities on MRI, extending beyond the typical context of hemorrhage. The mnemonic aids listed on the right-hand side to provide practical tools for recalling different etiologies to consider when assessing hyperdense intracranial CT lesions with corresponding T1W MR hyperintensity. Mnemonic for CT hyperintense lesions with high T1W MR signal intensities is “My Best Friend is Pretty Cool”, where M: melanin, mass (lymphoma), metastases (lungs/bronchus, breast); B: blood (methemoglobin component in subacute hemorrhage); F: some fat and slow flow; P: protein, paramagnetic substances (manganese, copper - metabolic ? diabetic striatopathy or hepatic encephalopathy); C: cystic lesions (colloid, craniopharyngioma, epidermoid cyst), cavernoma, contrast/gadolinium, and cholesterol.