¹⁸F-FDG Imaging: Pitfalls and Artifacts

Symmetric salivary gland uptake (projection view; arrows) shows mild uptake.

Laryngeal uptake. (A) Normal symmetric uptake in larynx. (B) Focal unilateral (arrows). Coronal view on left; transaxial view on right.

Thyroid inflammation. (A) Patient with known squamous cell carcinoma of upper lobe of right lung (thick arrow) who was being evaluated for initial staging. Note intense thyroid uptake due to Hashimoto’s thyroiditis. Also note normal stomach uptake (thin arrow). (B) A 57-y-old woman with history of breast carcinoma and left thyroidectomy who was being evaluated because of rising levels of tumor markers. Neck uptake was due to Hashimoto’s thyroiditis, which could easily have been mistaken for nodal uptake. C = coronal.

Focal thyroid uptake. (A) Focal thyroid uptake seen in right lobe of thyroid gland corresponding to focal density (arrow) seen on CT scan (B). ANT = anterior; POS = posterior; C = coronal.

(A) Cardiac uptake: Normal physiologic intense ¹⁸F-FDG uptake throughout myocardium. (B) Atrial uptake: Note inhomogeneous mild ¹⁸F-FDG uptake in enlarged right atrium resembling abnormal mediastinal nodal tissue uptake. Thick arrow points out normal stomach uptake. (C) Cardiac uptake: Apical scar with aneurismal formation.

Stomach uptake. (A) Normal uptake: mild diffuse uptake (arrows) conforming to stomach configuration. (B) Adenocarcinoma of stomach: focal uptake in region of stomach. Coronal view on left; sagittal view on right. (C) Stomach lymphoma: intense focal uptake (arrows). S = sagittal; C = coronal; ANT = anterior; POS = posterior.

Dilated esophagus. A 72-y-old man with known esophageal carcinoma. Note dilated esophagus with linear increased uptake on both sides. Chronic dilation is due to distal obstruction by tumor mass. Linear uptake is due to reactive inflammation. ANT = anterior; POS = posterior; S = sagittal; C = coronal.

Esophageal uptake. Esophageal uptake in patient with gastroesophageal reflux disease. S = sagittal; C = coronal; ANT = anterior; POS = posterior.

Colonic activity (projection view). Patient had bladder cancer, status post cystostomy, and ileal conduit. PET was done to rule out pelvic recurrence. Note nonspecific diffuse colonic activity (a), ileal conduit (b), urinary bag (c), and area of recurrence (d).

Cecal uptake. (A and B) Normal diffuse physiologic uptake (arrow) in cecum. C = coronal.

Dilated urinary bladder. Note prominent right (Rt) kidney collecting system, right ureter, and dilated urinary bladder.

Horseshoe kidney. (A) Horseshoe kidney (arrow) seen on ¹⁸F-FDG PET scan (projection view on left). Patient with Hodgkin’s lymphoma. (B) ^99mTc-Glucoheptonate scan confirms presence of horseshoe kidney.

Renal activity. (A) Intense activity in right kidney collecting system overlapping right lobe of liver, simulating a liver lesion. (B) ^99mTc-Dimercaptosuccinic acid image of same patient confirms that right kidney is slightly higher than left. Post = posterior.

Bladder diverticulum. (A) Bladder diverticulum caused by chronic bladder outlet obstruction by hypertrophied prostate. (B) Corresponding CT scan. ANT = anterior; POST = posterior; S = sagittal; C = coronal.

(A) Nephrostomy tube (arrow). (B) Diaper artifact. POS = posterior.

Muscle uptake. Symmetric muscle uptake in neck (arrows). C= coronal.

Intercostal muscle uptake due to persistent coughing (projection view).

Brown fat uptake. (A) Asymmetric neck uptake (arrows). (B) Intense symmetric uptake in adipose tissue (arrows). Brown fat can cause difficulty in scan interpretation. C = coronal.

Thymus uptake (coronal views). (A) Diffuse thymus uptake (arrow). (B) Focal thymus uptake (arrow).

Bone marrow. Intense ¹⁸F-FDG uptake in bone marrow is attributed to hematopoietic growth factor.

Spleen uptake (arrows) due to hematopoietic growth factor.

¹⁸F-FDG uptake in lymph nodes attributed to tuberculosis (projection view).

Fungal infection in liver of pediatric patient. (A) Before therapy (arrow). (B) Infection resolved on image after specific antifungal therapy.

Scar tissue from recent surgery. Patient underwent recent abdominal surgery for hernia repair. Note linear superficial increased ¹⁸F-FDG uptake along anterior abdominal wall conforming to abdominal scar tissue (arrow). S = sagittal; C = coronal; ANT = anterior; POS = posterior.

Abdominal fibrosis, honeycomb appearance. Patient had history of multiple abdominal surgeries leading to scattered segmental fibrosis. Image shows mild ¹⁸F-FDG uptake between dilated loops of bowel forming the honeycomb appearance. C = coronal.

Uptake in sternum after coronary artery bypass grafting. Patient had open-heart surgery 1 wk before ¹⁸F-FDG study. S = sagittal; C = coronal.

Postsurgical hematoma (arrows). Patient had excisional breast biopsy 10 d before ¹⁸F-FDG scan. ANT = anterior; POS = posterior; S = sagittal; C = coronal.

Intense aortic uptake due to inflammation (unstable plaque formation).