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VICARIOUS HEPATOBILIARY EXCRETION OF TC99M-MAG3
Authored By: Kartikeya Kantawala and Henry Royal.
Patient: 39 year old female
History: 39 year old female: Refractory large B cell lymphoma currently on chemotherapy with R- ESHAP, who was admitted with abdominal pain. CT demonstrated interval development of moderate left hydronephrosis and hydroureter due to an obstructive mass within the pelvis. Evaluate renal obstruction
Image Size:[small][as-submitted]

Fig. 1
Sequential dynamic renal images

Fig. 2
Post-Lasix dynamic

Fig. 3
Post-void supine (dynamic)

Fig. 4
Static images

Fig. 5
24 h static images

Fig. 6
CT
Image Size:[small][as-submitted]

Findings:

RADIOPHARMACEUTICAL: 7.8 mCi Tc-99m MAG3 i.v. and 40 mg furosemide i.v.

Mild retained activity in the prominent left collecting system, mild retained activity in the normal sized right collecting system.

 

On Post-Lasix sequential images, there is prompt clearance of pelvicalyceal activity on both sides.

Some activity is seen inferior to the left kidney on the postlasix projection. No abnormal fluid collection was seen on the CT. This activity was confirmed to be in bowel on the 24-hour delayed images.

DDx: 1. Vicariously (hepatobiliary) excreted Tc-99m MAG3 in bowel.
 
2. Urine leak
Diagnosis: Vicariously excreted Tc -99m MAG3 from the hepatobiliary system into the bowel.
General Discussion: Gallbladder uptake is occasionally visualized with commonly used nonhepatobiliary radiopharmaceuticals. Identification of the biliary tract by a nonhepatobiliary agent can identify disease, such as uptake of labeled white blood cells; however, in most cases, gallbladder uptake of nonhepatobiliary tracers is not due to pathology in these cases. It is important to avoid attributing gallbladder uptake to disease in the gallbladder or adjacent anatomic structures.

In this case, activity inferior to the left kidney, on the post-Lasix images was suspected to be a leak, however delayed 24 hour images confirm that the activity is in the bowel.

Tc99m MAG3 has a vicarious excretion pathway from the hepatobiliary system.
References: Niederkohr, Ryan D. MD; McDougall, I Ross MD, PhD; Clinical Nuclear Medicine. 32(12):915-919, December 2007; Incidental Gallbladder Visualization on Nonhepatobiliary Nuclear Medicine Studies: Case Series and Review of the Literature.
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Additional Details:

Case Number: 120355Owner(s): Kartikeya Kantawala and Henry RoyalLast Updated: 02-07-2013
Anatomy: Genitourinary (GU)   Pathology: Neoplasm
Modality: CT, Nuc MedAccess Level: Readable by all users, writable by NucMed Certifiers
Keywords: rsnmACR: 80000.12170

Case has been viewed 27 times.
Certified by Henry Royal on 10-15-2010

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