Case k -  Cholecystitis with HIDA correlation

The gall bladder is distended.  There is gall bladder wall edema and stranding in the fat around the gall bladder neck.  The common duct, pancreas, and bowel appear normal (though the bowel is very redundant!!!).  In this patient with right upper quadrant pain, and elevated WBC, this strongly suggests cholecystitis.

Notice the typical appearance of gall bladder wall edema.  The low attenuation rim is edema within the gall bladder wall.. The thin enhancing stripe is the gall bladder mucosa.  To differentiate this from pericholecystic fluid see how it tracks circumerentially around the gall bladder, even around the gall bladder neck (1 and 2).  The gall bladder is considered distended when all of its margins are convex, like a balloon with internal pressure.  This gall bladder looks like an inflated balloon.

There is stranding around the gall bladder neck,  The adjacent loops of colon are non-thickened.

The CT findings of acute cholecystitis include a distended, edematous gallbladder with surrounding stranding.  A suggestive secondary sign is hyperemia of the surrounding liver, which is not present in this case (but was seen on a previous case).  Individually, each of these findings is nonspecific.  Cholecystitis or prolonged fasting (> 8 hours) can cause a distended gallbladder.  Gall bladder wall edema is seen with hepatitis, cirrhosis, heart failure, and low protein states such as malnutirtion or cancer.  Pericholecystic stranding is also seen with pancreatitis and inflammation of the hepatic flexure. Together, however, the constellation suggests cholecystitis.

Now look at the images from the corresponding ultrasound.  Here, the gall bladder is not distended.  The gallbladder sort of flops back onto itself. -This portion of the wall is concave.  Distention is not based on size; rather on the shape of the walls.  Once the gall bladder is obstructed the internal pressure will increase and the walls will look like a balloon that is being inflated. However, there is edema in the gall bladder wall.  The wall of the gall bladder should be uniformly hyperechoic and thin.  The thin band of decreased echoes is the edema. There was no sonographic Murphy's sign.  This set of ultrasound findings is inconclusive for cholecystitis.

Because the  CT and ultrasound disagreed, a HIDA scan was performed.   This is a good idea if the diagnosis is suspected but uncertain.  HIDA is taken up by hepatocytes and excreted via bile.  When the cystic duct is patent HIDA can flow into the gall bladder.  If the cystic duct is obstructed than no HIDA gets into the gall bladder and it is not seen on the scan.  In this case there was no filling of the gall bladder after 90 minutes.  The gall bladder should be seen here.   Diagnosis: acute cholecystitis confirmed at surgery.

Did you find the normal appendix?

Take home points:

• The constellation of a distended gall bladder, gall bladder wall edema, and surrounding stranding on CT are individually nonspecific findings.  Together they suggest cholecystitis.
• Gall bladder edema looks like a hypoechoic band in the wall on ultrasound.  It does not have to be present circumferentially.
• HIDA scan is a useful test if the diagnosis is suspected but CT and ultrasound are inconclusive.