PET scan mis-alignment

This patient was scheduled for a PETCT with Diagnostic CT of the chest. The patient was positioned on the scanner, the tomogram was acquired followed by the whole body CT scan. Contrast was injected and the diagnostic CT of the chest was acquired. Even though the patient had used the rest room prior to the scan, she indicated she had to go again.

When the patient was repositioned on the scan table, a new topogram and whole body scan were entered into the original set-up (Siemens Biography 16, we copied and pasted the newer acquisition into the original acquisition page).

A new topogram and CT whole body were re-acquired followed by the whole body PET scan. The computer preformed the attenuation corrected image, with the above results, showing lack of data in the right half of the brain.

Review of the uncorrected data reveal that the data was good (below), which did not give any indication as to why right portion of the brain should be lacking in counts.

The study was re-processed manually using the second whole body CT data with the corrected results shown below. The image demonstrates complete uptake by the brain when compared with the first image.

The automatic processing selected the data from the first whole body CT acquired and not the second scan acquired prior to the PET scan. The differences in patient position from the first CT scan to the second CT scan is evident in the first set of PET processed data..

PET (F18FDG) - Atherosclerosis

Clinical history: multiple myeloma and temporal arteritis (inflammation and dammage to the  blood vessels that supply the head, particularly the large or medium arteries that branch from the neck and supply the temporal area), weight loss.

PET scan for temporal arteritis can produce detailed images of the blood vessels and highlight areas of inflammation. PET imaging for atherosclerosis of carotid and peripheral arteries have been documented in several studies see below.

The patient was injected with 15 mCi F18 FDG and imaged from brow to mid-thigh at 1.5 hours post injection, with CT for attenuation correction. blood glucose at the time of injection was 90 mg/dl. 

Findings - The images demonstrate diffuse metabolic activity in the carotid arteries suggesting active atherosclerosis or  inflammation. Diffuse activity is present in the aorta, large vessels of the thorax, pelvis, upper and lower extremities...

There was no evidence of metabolically active neoplasm.

Further reading

JNM June 2008: Atherosclerosis Inflammation imaging

Cutaneous Metastases

Breast cancer is known to metastasize to anywhere in the body, either by hematogenous or lymphatogenous routes. Cancers that have the highest tendency to metastasize to the skin include melanoma, breast, nasal sinuses, larynx and oral cavity.

Excluding melanoma, cutaneous metastases occur more often in breast cancer than in other diseases in women and is the most often encountered in clinical practice. In a recent study, that included 12146 patients with internal malignancies, the rate of CM associated with breast carcinoma was 2.42 percent.

PETCT - subcutaneous metastases - transverse image shows extent of disease located in the soft tissue at the upper lobe of the liver.

projection image

Another example of a female with a clinical history of breast cancer who presents with "nodular" cutaneous metastases. image includes PET WB coronal slice and comparative transverse PET and CT slices.  Localized nodules are the most common presentation, occurring in 10% of patients.

Reading:
Cutaneous metastases of breast carcinoma: a case report.

Cutaneous and subcutaneous metastases of adenocarcicoma of the colon and rectum