ANSWERS GRADED A+
✔✔Dissection - ✔✔Occurs when blood enters into the wall of an artery dissecting the
layers and creating a cavity or false lumen. Ascending aorta is type A, descending type
B.
Black blood imaging often used.
Intimal flap appears as a hypointense line with a linear or S shape.
✔✔Fatty Liver - ✔✔Imaging findings:
Higher than normal signal of T1 or T2 images
In phase/out of phase sequences: when fat and water coexist in a voxel owing to
chemical shift there will be signal drop out from fat on out of phase imaging.
Can be diffuse or multifocal.
Spleen is used as an internal reference for signal intensity.
✔✔Fistula - ✔✔MRI is the imaging modality of choice.
Active fistulous tracts are typically:
T1: isointense to muscle
T2: high signal compared to fat
T1 C+: enhancing. walls of the fistulous tract and abscess will enhance.
look for dumbbell shape on coronal and horse shoe on axial imaging.
Old, healed fistulae typically demonstrate low T1 and T2 signal without contrast
enhancement, reflecting fibrosis.
✔✔Focal nodular hyperplasia (FNH) - ✔✔Benign tumour like lesion of the liver.
Incidental finding.
T1 slightly hypointense
T2 slightly hyperintense
*could appear iso intense on T1 and T2
T1 CE demonstrates immediate hyperintensity following Gd that becomes isointense
during the portal venous phase and isointense on delayed imaging.
SPIO agents are taken up by the kupffer cells so the lesion will be hypointense on T2*
sequences.
✔✔Hemangioma (liver) - ✔✔Common benign liver tumour, usually 1-2 cm. Incidental
finding. Originate from the epithelial cells. Contains multiple large vascular channels.
Often found in people with FNH.
, T1 hypointense in relation to liver
T2 hyperintense in relation to liver
Dynamic imaging: characteristic feature is discontinuous peripheral nodular
enhancement with progressive centripetal fill in. Hyperintense with increasing signal
over 15-30 mins.
✔✔Hepatic abscess - ✔✔T1 usually hypointense
T2 tends to have hyperintense signal perilesional edema manifests as high signal
intensity on T2
T1 C+ (Gd)enhancement of the capsule, multiple septations may be visible
DWI: tends to have high signal within the abscess cavity and high signal at the
periphery
ADC: tends to have low signal within the abscess cavity and high signal at the periphery
✔✔Hepatic cell carcinoma (HCC) - ✔✔AKA hepatoma
Most common primary malignant liver tumour.
T1: hypointense
T2: hyperintense
T1 CE: variable enhancement
SPIO hyperintense due to failure to accumulate iron within the tumour cells
✔✔Horseshoe kidney - ✔✔Congenital anomaly characterized by fusion of the lower
(90%) or upper (10%) poles of the kidneys. Fairly common (1:500)
T1 imaging is best to see this anatomical anomaly.
✔✔Inflammatory bowel disorders- crohn's - ✔✔Inflammatory condition that can affect
the entire alimentary canal, but usually affects the terminal ileum.
T2 and T1 CE with fat suppression demonstrates dilated bowel and inflammatory
changes.
3D GRE shows skip lesions, mural enhancement, and mesenteric inflammatory
changes.
✔✔Iron deposition (hemochromatosis) - ✔✔A hereditary condition in which the small
bowel absorbs an excess amount of iron.
Iron is initially stored in hepatocytes as the disease progresses and then moves into the
pancreas, GI tract, kidneys, heart, joints and endocrine glands resulting in destruction of
these tissues.
Affected hepatocytes appear hypointense because of iron (paramagnetic) shortening
the T1 and T2 relaxation times.
Best seen on GRE T2 which show magnetic inhomogenties well.
✔✔Kidney carcinoma - ✔✔Most common malignancy affecting the kidneys.