Imaging Pitfalls in CECT Abdomen Interpretation

Context-Specific False Positives

The American College of Radiology recommends that treated pathologic lymph nodes developing central low-density with rim enhancement should be scored as benign if there is no FDG uptake on PET, even when they appear necrotic on CECT alone 3
The American College of Radiology emphasizes that radiation injury to soft tissue can have a tumefactive appearance on anatomic images with marked FDG uptake from inflammation, representing the most common cause of false-positives in high-suspicion categories 1
Newly enlarging nodes with questionable heterogeneous enhancement on CECT alone may represent reactive inflammatory changes rather than true pathologic necrosis 2

Early CT scanning (within 72 hours) will not adequately show necrotic or ischemic areas in acute pancreatitis, potentially leading to underestimation rather than false-positive identification 4, 5
CECT achieves close to 100% sensitivity for pancreatic necrosis only after 4 days from symptom onset 4, 5

The American College of Radiology recommends always comparing current imaging with baseline posttreatment studies and pretreatment imaging to distinguish expected posttreatment changes from new pathologic necrosis 2
When CECT alone shows questionable necrotic features without definitive morphologic abnormalities, PET imaging should be obtained before biopsy to improve specificity 2, 3
True pathologic necrotic nodes demonstrate specific features: new necrosis, extracapsular extension, or progressive enlargement with heterogeneous enhancement 1, 2, 3