The objective of this educational paper is to describe the most common focal and diffuse hepatic lesions with a characteristic hyperintense signal on T1-weighted images and to provide a differential diagnosis among them.
Signal intensity of T1 weighted images is due to several factors such as the chemical composition of tissues,
scanning sequences parameters and use of contrast medium . T1 tissue relaxation time is the main factor that sets signal intensity in Magnetic Resonance Imaging (MRI) .
Normal liver tissue has a short T1 relaxation time : for this reason,
only lesions that contain T1-shortening elements appear relatively hyperintense. Below are the most common causes of T1 hyperintensity:...
Findings and procedure details
According to their histopathology liver lesions can be distinguished in benign and malignant. Benign liver lesions Diffuse pathologies: Diffuse hepatic steatosis ( Fig. 1 ): due to overload of triglycerides within the hepatocytes; may be distinguished an alcoholic- and nonalcoholic-disease.
Since it is a benign lesion,
there are no mass effect/infiltration of liver vessels and no contrast-enhanced areas of inhomogeneities.
Out-of-phase T1w-images show loss of signal. Wilson’s disease: an...
MRI is a reliable diagnostic tool in recognizing focal and diffuse T1 hyperintense liver lesions and providing a characterization through their specific influence of T1 relaxation time. Knowledge of the T1 signal characteristics of substances such as fat and hemoglobin degradation products allow the radiologist to perform a correct diagnosis.
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