Granulomatous disease: is it a nuisance or an asset during PET/computed tomography evaluation of lung cancers?

• Published in: Nuclear medicine communications Vol. 29; no. 7; pp. 623 - 627
• Main Authors: Chundru, Surya, Wong, Ching-yee Oliver, Wu, Dafang, Balon, Helena, Palka, Jane, Chang, Chih-Yung, Gaskill, Marianne, Cheng, Cheng-Yi, Huang, Wen-Sheng, Fink-Bennett, Darlene
• Format: Journal Article
• Language: English
• Published: England Lippincott Williams & Wilkins, Inc 01-07-2008
• Subjects: Adult; Aged; Aged, 80 and over; Diagnosis, Differential; Female; Granulomatous Disease, Chronic - diagnosis; Humans; Lung Neoplasms - diagnosis; Male; Middle Aged; Positron-Emission Tomography - methods; Reproducibility of Results; Sensitivity and Specificity; Solitary Pulmonary Nodule - diagnosis; Subtraction Technique; Tomography, X-Ray Computed - methods
• ISSN: 0143-3636
• DOI: 10.1097/MNM.0b013e3282fdc979

OBJECTIVESTo evaluate combined PET-computed tomography (CT) criteria for differentiating between granulomatous disease (GD) and malignancy (CA) in oncologic PET–CT studies.
METHODSSixty-two patients who were referred for fluoro-2-deoxyglucose (FDG) PET–CT evaluation of pulmonary lesion(s) without a history of concurrent infection were studied. PET–CT was performed 1.5 h after intravenous administration of 555 MBq F-FDG in the fasting state with oral contrast. Combined PET–CT criteria including (i) calcifications (Ca) within lymph nodes, (ii) Ca in lung nodules, (iii) liver and/or spleen Ca, (iv) locations of lung lesion(s), (v) hilar FDG uptake, (vi) comparison of lung versus maximum mediastinal FDG uptake, (vii) lymph node uptake not in the most probable lymphatic drainage pathway from a particular lung lesion, and (viii) extra pulmonary abnormal FDG uptake were each assigned a numerical score (0–3) with progressively higher score and sum of scores toward the increasing likelihood of GD. These patients either had pathological confirmation by biopsy/resection or were followed radiographically for a period of 2 years (CA=13; GD=49). Discriminant analysis was performed on all the above criteria with this gold standard. Simple t-test and box plot analysis were also performed on the summation of the scores (from 0 in CA to 13 in GD).
RESULTSWhen all eight criteria were entered into discriminant analysis, the combined PET–CT criteria classified correctly 71% of patients with a sensitivity of 65% and specificity of 92% for GD. The most significant discriminating criterion was FDG uptake in the lung lesion(s) less than maximum mediastinal uptake (P=0.01). The sum scores in GD and CA were significantly different (4.9±2.4 vs. 3.2±1.5, respectively, P=0.014). Box plots showed a clear separation at a cut-off value of around 3.5.
CONCLUSIONResults show that the set of combined PET–CT criteria are highly specific for GD, which is not necessarily a nuisance during oncologic evaluation. Knowledge of these criteria may attribute some of the abnormal PET findings to GD, which is a useful asset for quick recognition and clinical interpretation.