Ann Thorac Surg 2007;84:1798. doi:10.1016/j.athoracsur.2007.07.071
© 2007 The Society of Thoracic Surgeons
Correspondence
Reply
Robert J. Cerfolio, MD, FACS,
Ayesha S. Bryant, MD, MSPH
University of Alabama at Birmingham, Department of Cardiothoracic Surgery, 703 19th St S, ZRB 736, Birmingham, AL 35294
(Email: robert.cerfolio{at}ccc.uab.edu).
To the Editor:
Dr Fleckenstein [1] has raised an important and valid point and essentially he is correct. It is true that the uptake of a mediastinal lymph node is not ever really zero, but rather it is "not reported." The maximal standard uptake value (maxSUV) of the mediastinal nodes that are not reported were labeled 0 by our statistical analysis and as defined in the article [2], because no other number was provided from them. Moreover, most positron emission tomographic (PET) centers do not report background mediastinal maxSUVs. Thus, to label them anything else would have been inaccurate. We could have therefore stated that the median maxSUVs of these lymph nodes was "not reported." but one can see the awkwardness of this in a numerical table. However, we agree with Fleckenstein [1] that this would have been a more accurate descriptor of these nonreported mediastinal lymph nodes.
As for borderline lymph nodes that have high maxSUVs, but less than 4.5 or 5, we have reported this problem in several of our other studies on PET for patients with lung cancer. There are often false positives on integrated PET and computed tomographic scans secondary to granulomatous or inflammatory disease in N2 mediastinal and N1 hilar lymph nodes. For this reason we now often use the positive predictive ratio (PPR) for mediastinal N2 lymph node pathology, as we have previously defined and published [3]. When the ratio of the maxSUV of the mediastinal lymph node divided by the maxSUV of the primary tumor is 0.56 or greater, there is a 94% chance that mediastinal lymph node is malignant (assuming the primary pulmonary nodule is malignant). Thus, for his example, the maxSUV of the 4R node of 2.2 would be divided by the maxSUV of the pulmonary nodule and the PPR could be easily calculated. We also generated data on the maxSUV/cm2 of tumor volume and hope to have a publication on this phenomenon as well in the near future. Perhaps, the better ratio is not just the absolute value of the maxSUV of the lymph node or the pulmonary nodule, but rather the maxSUV/cm2 of the size of the lymph node and the nodule. Therefore, the new ratio would be: maxSUV of mediastinal lymph node/cm2 of the size of the lymph node/maxSUV of the pulmonary nodule/cm2 of the pulmonary nodule. We thank Dr Fleckenstein [1] for his interest and question.
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References
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- Fleckenstein JL. Maximum standard uptake values of mediastinal nodes on PET and CT (letter) Ann Thorac Surg 2007;84:1797-1798.[Free Full Text]
- Bryant AS, Cerfolio RJ, Klemm KM, Ojha B. Maximum standard uptake value of mediastinal lymph nodes on integrated FDG-PET-CT predicts pathology in patients with non-small cell lung cancer Ann Thorac Surg 2006;82:417-423.[Abstract/Free Full Text]
- Cerfolio RJ, Bryant AS. Ratio of maximum standardized uptake on FDG-PET on mediastinal (N2) lymph nodes to the primary tumor may be a universal predictor of nodal malignancy in patients with nonsmall-cell lung cancer Ann Thorac Surg 2007;83:1826-1830.[Abstract/Free Full Text]
Related Article
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Maximum Standard Uptake Values of Mediastinal Nodes on PET and CT
- James L. Fleckenstein
Ann. Thorac. Surg. 2007 84: 1797-1798.
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