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SPECT ARTIFACT
Authored By: Joanna Fair and Barry Siegel, Prof of Radiology.
Patient: 64 year old
History: Elevated 6-HIAA.
Image Size:[small][as-submitted]

Multimedia: 129392_1_submitted.avi
Maximum-intensity-projection (MIP) images of the processed SPECT data from an In-111 pentetreotide scan, obtained 24 hours post injection.

Fig. 2
Same reconstructed SPECT data, displayed as transaxial images.

Multimedia: 129392_3_submitted.avi
Raw data (projection images) from the same scan.

Multimedia: 129392_4_submitted.avi
Subset (few frames) of projection data showing the data collapse into a single point before disappearing.

Multimedia: 129392_5_submitted.avi
Repeat imaging of the same patient acquired 2 hours later. Maximum- intensity-projection (MIP) images are shown.
Image Size:[small][as-submitted]

Findings:

Radiopharmaceutical: 6 mCi In-111 pentetreotide i.v.


Please review Fig. 1 and Fig. 2.


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There is a rod-like area of apparent increased activity on the SPECT maximum-intensity projection (MIP) images (Fig. 1).� The transaxial filtered-back-projection SPECT images show a�corresponding linear�streak of increased activity�(Fig. 2).

What would you do next?

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Examination of the raw�projection images (Fig. 3) shows absent data for the last approximately 20 frames of the acquisition.� Focusing on just the last few frames with data (Fig. 4), the data collapse to a single point before disappearing.


What might be the cause?

DDx: SPECT artifact.
Diagnosis: SPECT artifact, presumably�due to a detached ring cable.
General Discussion:

The SPECT camera head is powered by a ring cable, which, as the head rotates, can get stretched and lose contact.� As the cable began to lose contact, likely all the acquired data briefly collapsed into a single acquisition point, which created the hot pixel on the raw data and the rod of intense activity on the back-projected reconstructed data.� As the cable further detached, all contact was lost and the image disappeared.

The patient was reimaged approximately two hours later; the artifact was resolved (Fig. 5).� This new acquisition showed no focal abnormalities suggestive of a neuroendocrine tumor.
Comments:
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Additional Details:

Case Number: 129392Owner(s): Joanna Fair and Barry Siegel, Prof of RadiologyLast Updated: 02-07-2013
Anatomy: Gastrointestinal (GI)   Pathology: Other
Modality: Nuc MedAccess Level: Readable by all users, writable by NucMed Certifiers
Keywords: otnm, spect, artifact, octreotide, octreoscan, somatostatin receptorACR: 70000.93000

Case has been viewed 52 times.
Certified by Barry Siegel on 09-19-2009

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