July 21, 2014

Fatty Liver

Axial "in-phase" MR image shows increased signal intensity of the liver.
Axial "opposed-phase" MR image shows decreased signal of the entire liver when compared with the same areas on in-phase image. 

  • Triglyceride accumulation within cytoplasm of hepatocytes
  • Can be due to alcoholic liver disease, nonalcoholic fatty liver disease, viral hepatitis, drugs
  • May progress to steatohepatitis and cirrhosis
  • Avoid the use of "fatty infiltration of the liver", which is misleading because fat deposition in Fatty Liver is in hepatocytes - rarely in other cell types
  • Sensitivity/specificity for detection:
    • Ultrasound = 60-100% / 77-95%
    • Non-contrast CT = 43-95% / 90%
    • Chemical-shift MRI = 81% / 100%

MR Imaging

  • Because protons in water and fatty acid molecules precess in different resonance frequency, proton chemical shift imaging can be utilized to image this difference
  • If images are obtained when fat and water protons are "in-phase", their signals are additive (brighter). If they are "out-of-phase", their signals cancel each other (structure becoming darker)
  • Amount of hepatic fat can be quantified by assessing the degree of signal loss
Hamer OW, Aguirre DA, Casola G, et al. Fatty liver: imaging patterns and pitfalls. Radiographics 2006; 26:1637-1653.

July 11, 2014

Focal Urinary Bladder Wall Thickening

Axial and sagittal-reformatted CT images show focal thickening of the posterior wall of the urinary bladder (arrows) with increased enhancement relative to normal bladder wall. 

Differential Diagnosis

  • Tumor (benign, malignant, metastasis)
  • Adherent clot
  • Infection/inflammation (TB, cystitis cystica/glandularis, malakoplakia, schistosomiasis)
  • Trauma (mural hematoma)
  • Extravesical pathologies (spread of extravesical inflammation or tumor, endometriosis)
  • Transitional cell carcinoma accounts for most focal bladder masses
  • Most of the time it is impossible to distinguish tumor from other causes of focal wall abnormality and cystoscopy is necessary
Our case: Transitional cell carcinoma in a 73-year-old female


Patel U. Imaging And Urodynamics Of The Lower Urinary Tract. Springer 2010.
Bhargava. Ultrasound Differential Diagnosis. Jaypee Brothers Publishers, 2005.

July 1, 2014

Krukenberg Tumors

Axial and coronal-reformatted CT images of a 41-year-old woman shows an enlarged, solid-appearing right ovarian mass (arrows). The left ovary (not shown) is normal. 

  • Metastatic tumor to the ovary that contains mucin-secreting, signet ring cells
  • Usually originate from primary tumors of GI tract (most common = colon and stomach)
  • 10% of all ovarian tumors
  • Occur in reproductive age
  • Nonspecific appearance. Can be solid or mixed solid/cystic
  • High suspicion for ovarian metastasis if:
    • Bilateral 
    • Complex-appearing ovarian masses
    • Known GI tract tumor (esp. colon and stomach)
    • MRI showing T1/T2 hyper intensity due to mucin
Our case: Ovarian metastasis from primary gastric cancer.

Jung SE, et al. CT and MR imaging of ovarian tumors with emphasis on differential diagnosis. Radiographics 2002; 22:1305.