Charles M. Intenzo MD, Presenter: Nothing to Disclose

Alexandros Pappas MD, Abstract Co-Author: Nothing to Disclose

Sung M. Kim MD, Abstract Co-Author: Nothing to Disclose

Donna D Carstens MD, Abstract Co-Author: Nothing to Disclose

Gregory Kane MD, Abstract Co-Author: Nothing to Disclose

Rohit Kumar MD, Abstract Co-Author: Nothing to Disclose

Bharat Awsare MD, Abstract Co-Author: Nothing to Disclose

Achala Donuru MD, Abstract Co-Author: Nothing to Disclose

FDG-PET/CT is a well established modality for evaluating indeterminate solitary pulmonary nodules (SPN).  Although the sensitvity for detecting malignancy is considered quite high, the specificity is lower.  By adding delayed imaging (Dual-Point PET/CT), the specificity for malignancy improves, since malignant SPN increase glucose utilization over time, i.e. an increase by > 10% in the maximum standardized uptake value (SUV Max).  By contrast, a decrease or no significant change in SUV max suggests benign etiology.  We observed, however, that it was not uncommon for biopsy-proven malignant nodules to show either no significant change or a significant decease (> 10%) in SUV Max on delayed imaging.  Our aim was to (1) determine the frequency of this pattern and (2) to correlate with  histopathology.

Over a 4-year period, we collected all cases of FDG-PET/CT scans used for SPN evaluation in which the final diagnosis was lung malignancy, yet the SUV Max either did not significantly  change, or decreased by 10% or more on delayed imaging. 

A total of 42 patients met the above criteria, 26 men and 16 women.  In  22 of the patients (Group A), the SUV Max decreased by > 10%, which was considered a  significant decrease.  Of these, 13 patients had adenocarcinoma, 2 had squamous cell, 4 had small cell, and 3 had bronchoalveolar (BAC).  The remaining 20 patients (Group B) demonstrated either no significant change  in SUV Max, or a decrease less than 10%; 12 had adenocarcinoma, 1 had small cell and 7 had BAC.

(1) Although a significant increase in SUV Max in dual-point  FDG PET/CT imaging generally indicates SPN malignancy, a decrease or lack of change in  SUV does not necessarily mean a benign etiology. (2)  Adenocarcinoma is the most common cell type in which SUV Max decreases or does not significantly change, likely a reflection of tumor differentiation.   

A lack of change or a significant decrease in SUV Max over time of an SPN does not exclude malignancy and this pattern is unreliable in SPN evaluation.

Intenzo, C, Pappas, A, Kim, S, Carstens, D, Kane, G, Kumar, R, Awsare, B, Donuru, A, Does a Decrease in SUVmax in Dual-Point FDG-PET/CT Imaging Reliably Exclude Malignancy of a Solitary Pulmonary Nodule (SPN)?.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11008002.html