MIR Teaching file case pa007

Case Author(s): Jeffrey Yu, M.D. and Henry Royal, M.D. , 8/14/99 . Rating: #D2, #Q5

Diagnosis: Parathyroid adenoma masked by poor positioning

Brief history:

82 year old female with elevated serum calcium on routine blood work

10-minute and 2 hour anterior images of neck and upper mediastinum

View main image(pa) in a separate image viewer

View second image(pa). The same 10 minute image, but with a repeat 2-hour image with the patient's head in Waters position.

Full history/Diagnosis is available below

Diagnosis: Parathyroid adenoma masked by poor positioning

Full history:

82 year old female with elevated calcium on routine blood work. Parathyroid imaging utilizing Tc-99m Sestamibi was requested to evaluate for parathyroid adenoma.

Radiopharmaceutical:

Tc-99m Sestamibi (Cardiolite®)

Findings:

Notice the difference in positioning of the patient's head between the initial 10-minute image and the first 2-hour delayed image. On the first 2-hour image, the patient's head has drooped significantly such that the chin is projected over the upper portion of the thyroid gland. Repeat imaging with the patient's head positioned appropriately demonstrates a persistent focus of increased activity in the vicinity of the upper pole of the right lobe of the thyroid, consistent with a parathyroid adenoma.

Discussion:

Proper positioning is crucial for proper imaging. This case nicely demonstrates how a slight change in positioning lead to attenuation of the finding by the patient's chin.

Followup:

SPECT imaging was performed which confirmed the focus of activity in the upper pole of the right lobe of the thyroid. The patient is scheduled for surgery at a later date.

View followup image(pa). Coronal SPECT images confirm the focus of increased activity in the upper pole of the right lobe of the thyroid seen on the repositioned 2 hour image.

Major teaching point(s):

1) Importance of proper positioning in image interpretation. 2) Imaging appearance of a parathyroid adenoma using Tc-99m Sestamibi (Cardiolite®)

Differential Diagnosis List

Parathyroid Adenoma Normal

ACR Codes and Keywords:

General ACR code: 63
Lung, Mediastinum, and Pleura:

6.3159 "Other include: lipoma, parathyroid adenoma exclude: lipid deposition in Cushing disease or steroid therapy (.512)"

References and General Discussion of Parathyroid Scintigraphy (Anatomic field:Lung, Mediastinum, and Pleura, Category:Neoplasm, Neoplastic-like condition)

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Case number: pa007