On MRI, a tissue with a short T1 relaxation time will appear bright on T1-weighted sequences. Which of the following tissues is characteristically hyperintense on T1-weighted MRI?
- A Cerebrospinal fluid
- B Subcutaneous fat ✓
- C Cortical bone
- D Lung parenchyma
Correct answer: B. Subcutaneous fat
Explanation
Subcutaneous fat has a short T1 relaxation time due to the efficient energy transfer from protons to the surrounding lattice in fatty tissues, resulting in bright (hyperintense) signal on T1-weighted sequences. CSF has a long T1 and appears dark on T1W and bright on T2W images. Cortical bone has negligible mobile proton density and appears black on all sequences. Understanding T1 and T2 behavior of tissues is fundamental to interpreting MRI; fat is also suppressed using fat-saturation or STIR techniques to unmask pathology.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.