A 38 year old man presents with worsening upper abdominal pain over the past 3 days. He had one episode of vomiting prior to arriving to the emergency department. Past medical history is significant for hypertension and morbid obesity, with BMI of 53.
Initial imaging evaluation consisted of a CT of the abdomen and pelvis:
This was followed by a right upper quadrant ultrasound:
Hepatobiliary imaging (HIDA) with Tc99m Mebrofenin (after initial blood flow phase):
This case demonstrates the classic findings of acute calculus cholecystitis. It’s unclear to me why this patient underwent all of these tests, supposedly the physical examination findings were not typical.
CT images show gallbladder wall thickening (best seen at the superior aspect of the gallbladder) as well as extensive surrounding fat stranding and edema.
Ultrasound images demonstrate a shadowing gallstone in the gallbladder neck, as well as marked wall thickening with edema and hyperemia of the gallbladder wall.
HIDA images demonstrate non filling of the gallbladder during the initial 60 minutes after radiotracer administration (above) as well as after administration of morphine (below). Enterogastric reflux of radiotracer activity is incidentally noted.
Ultrasound is widely preferred as the initial imaging modality in patients suspected of cholecystitis. This test is fast, inexpensive, lacks ionizing radiation, and has high diagnostic accuracy. Worthen NJ, et al. AJR 1981;137:973-978. Ralls PW, et al. Radiology 1985;155:767-771.
It is important to remember, however, that metaanalyses published in both 1994 and 2012 have found that cholescintigraphy (HIDA) has higher diagnostic accuracy for acute cholecystitis. Shea JA, et al. Arch Intern Med 1994;154:2573-81. Kiewiet JJ, et al. Radiology 2012;264:708-20.
Though not uncommonly performed for this indication (especially overnight), CT has lower sensitivity and specificity than ultrasound in diagnosing cholecystitis, due to inability to evaluate for tenderness and the fact that many gallstones are not reliably identified. Harvey RT, et al. Radiology 1999;213:831-6. Benarroch-Gampel J, et al. J Am Coll Surg 2011;213:524-30. However CT may be helpful in identifying complications, such as abscess or gangrenous/emphysematous cholecystitis. Shakespear JS, et al. AJR 2010;194:1523-9.
Although all of these tests make the diagnosis in this case, HIDA imaging can be a good choice in morbidly obese patients (given poor acoustic penetration with ultrasound, image noise and less specific findings with CT). The 140 keV photons of Technetium are less affected by attenuation than lower energy xrays used in CT.
Acute Cholecystitis
Question 1 |
A | Increased radiotracer activity in the common bile duct after morphine administration |
B | Enterogastric reflux of radiotracer activity |
C | Slow clearance of the radiotracer from the hepatic parenchyma |
D | Retention of radiotracer activity in the duodenum prior to morphine administration |
Question 2 |
A | Hypoattenuation of the gallbladder wall |
B | Enlarged cystic artery |
C | Mass effect of the gallbladder fundus on the abdominal wall |
D | Wall thickening and hyperemia of the hepatic flexure |