Case Author(s): Michael Roarke, MD and Barry A. Siegel, MD , 4/12/96 . Rating: #D3, #Q5

Diagnosis: Incorrect radiopharmaceutical administered for bone scintigraphy in patient with Paget's disease.

Brief history:

74-year old woman with back pain and elevated serum alkaline phosphatase level.


Anterior and posterior images at 4 hours.

View main image(bs) in a separate image viewer

View second image(bs). Anterior and posterior images at 3 hrs.

View third image(xr). Plain radiograph of the hand.

Full history/Diagnosis is available below

Diagnosis: Incorrect radiopharmaceutical administered for bone scintigraphy in patient with Paget's disease.

Full history:

74-year old woman with no history of osteoporosis and on no medications who presents with an elevated serum alkaline phosphatase level. Evaluate for malignancy.


Tc-99m DTPA and Tc-99m MDP


On the initial examination of 4-8-96, there is no significant osseous activity seen on the images. . Virtually all of the administered activity is within the soft tissues and in the kidneys, collecting systems, and bladder.


The patient was not receiving therapy with diphosphonate or bisphosphonate agents. There was no history of osteoporosis or other bone disorders. The syringe used to inject the patient with tracer was labeled Tc-99m MDP. Given the suspicion of a radiopharmaceutical error, we inspected the multi-dose vial from which the patient's dose had been drawn. While the outer shielding container was labeled Tc-99m MDP, the multi-dose vial inside was labeled Tc-99m DTPA. The patient subsequently returned for bone scintigraphy two days later with Tc-99m MDP. These images reveal markedly increased tracer activity in the left ulna, sacrum, and proximal phalanx of the fourth digit of the left hand. Plain radiographs of each of these areas were obtained, showing the characteristic findings of Paget's disease. Radiographs of the sacrum did not suggest sarcomatous degeneration of the sacral Paget's disease.

Major teaching point(s):

The incorrect administration of Tc-99m DTPA in this patient does not constitute a radiopharmaceutical misadministration (as currently defined in U.S. Nuclear Regulatory Commission regulations) since a byproduct, non-radioiodine radiopharmaceutical was involved and the effective dose equivalent was less than 5 rem and the critical organ dose was less than 50 rem. Nonetheless, it is always essential to verify that the correct radiopharmaceutical is being given to the correct patient in the correct dose.

Differential Diagnosis List

If incorrect radiopharmaceutical administration has been excluded, the differential diagnosis for poor skeletal localization of Tc-99m MDP includes concomitant diphosphonate therapy, poor radiochemical purity of the Tc-99m MDP preparation, congestive heart failure, and osteoporosis.

ACR Codes and Keywords:

References and General Discussion of Bone Scintigraphy (Anatomic field:Skeletal System, Category:Other generalized systemic disorder)

Search for similar cases.

Edit this case

Add comments about this case

Return to the Teaching File home page.

Case number: bs057

Copyright by Wash U MO