Overview The advantages of PET/CT include identification of abnormalities which can be targeted for percutaneous biopsy to determine metastatic disease. However, it is difficult for both the clinician and patient when positive PET findings do not have a correlate identified on CT. We present the first published case of successful biopsy of an isolated PET avid bone lesion without a CT correlate in a patient with newly diagnosed esophageal adenocarcinoma using a PET guided biopsy technique.

PET Guided Biopsy of Isolated Bone Metastasis in GE Junction Adenocarcinoma

Mark Joseph, MD,¹ Amir H. Khandani, MD,² John P. Clarke, MD,² Michael O. Meyers, MD¹
Departments of Surgery¹ and Radiology,² University of North Carolina, Chapel Hill, NC.

Contact: Michael O. Meyers, MD. E-mail This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Citation: Joseph M, Khandani AH, Clarke JP, and Meyers MO. PET Guided Biopsy of Isolated Bone Metastasis in GE Junction Adenocarcinoma. J Surg Radiol. 2010 Oct 1;1(2).

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PET Guided Biopsy of Isolated Bone Metastasis in GE Junction Adenocarcinoma	940 Kb

Received July 26, 2010. Accepted August 9, 2010. Epub August 9, 2010.

Copyright: © 2010 Surgisphere Corporation. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Contents

- Introduction
- Case Report
- Discussion
- Disclosures
- References

Introduction

Positron emission tomography (PET), with the glucose analogue F-18-fluorodeoxyglucose (FDG) has become the standard of care for systemic staging especially in esophageal cancer.¹ A major disadvantage, however, is the fact that this method yields only limited information on the exact anatomical location of the lesion.² For this reason, the combination of PET and CT (PET/CT) has emerged as the diagnostic test of choice. The impact of PET/CT in initial staging, treatment response and in restaging of recurrent disease in esophageal cancer is now evident in that it has been shown to have superior accuracy when compared with PET and CT performed separately.^3,4 When compared to PET reviewed side-by-side with CT, integrated PET/CT has been shown to be of more value in the interpretation of disease sites in the neck, locoregional lymph nodes, and in regions of postoperative or post treatment anatomical distortion in cases of esophageal cancer with additional suspicious malignant sites.³

One of the challenges in determining appropriate management of the patient presenting with esophageal cancer is interpreting the data derived from cross-sectional imaging. PET/CT technology has improved the ability to definitively identify those patients who present with metastases not only in esophageal cancer but other cancers as well, without invasive surgical procedures thereby increasing accuracy over either PET or CT alone.^3,5 PET, like any diagnostic study, can be fraught with false-positive findings, although the reported rate of false-positive PET findings in the setting of esophageal cancer is very low. In the most complete study examining PET staging in esophageal cancer, the false-positive rate was 3.7%.⁶ One of the advantages of PET/CT is that the abnormalities identified can often be targeted for biopsy, either percutaneously or surgically, in order to accurately determine whether they represent metastasis. However, this is not possible when there are limited areas of abnormality that are seen only on the PET portion of the study but there is no correlative finding on the CT portion. This situation leaves both the patient and the clinician in a difficult position, as the interpretation of the scan findings may significantly alter management.

In this report, we present a case of a young patient with newly diagnosed adenocarcinoma of the distal esophagus who had an isolated area of abnormality in the iliac wing on the PET portion of a PET/CT scan, without any correlative findings on the CT portion. We biopsied this area under PET guidance to provide diagnostic material that confirmed stage IV disease.

Case Report

We present a 54-year-old white female who presented with a four week history of dysphagia, odynophagia and epigastric pain as well as a 15 pound weight loss history over a period of six to eight weeks. She underwent esophagogastroduodenoscopy (EGD) which showed an ulcerating lesion in the distal esophagus with biopsies showing poorly differentiated invasive adenocarcinoma of the distal esophagus. CT scan findings included marked thickening of the distal esophagus and slightly enlarged lymph nodes at the gastrohepatic ligament. By endoscopic criteria she was staged as a T3 N1 Mx lesion.

Further workup for metastatic disease included whole body PET/CT. Findings included increased uptake in the area of the distal esophagus, corresponding to the known primary as well in the gastrohepatic ligament region which was consistent with nodal metastases in the celiac region seen on EUS. There was also a focus of increased FDG uptake in the left iliac bone that was concerning for metastasis but did not correspond to any findings on the CT portion of the exam. (Figure 1A and Figure 1B) Without an obvious target on cross-sectional imaging to biopsy, it was elected to attempt biopsy of this lesion using PET guidance. (Figure 2) This yielded malignant cells consistent with metastatic adenocarcinoma of esophageal origin on pathologic analysis. Subsequent to the diagnosis of stage IV disease, the patient was treated with systemic chemotherapy followed by radiation therapy to control eventual progression of the primary tumor. The patient was spared a non-curative esophagectomy.

Figure 1. Axial (top) and coronal (bottom) images of abdomen/pelvis showing metastatic deposit.

Figure 2. PET guided biopsy of metastatic lesion showing needle inserted into mass. This biopsy later revealed malignant cells consistent with metastatic adenocarcinoma.

Discussion

Positron emission tomography (PET) is increasingly recognized as a powerful oncologic tool.³ PET enables detection of an increased glucose metabolism that is characteristic of most malignant cells. Since PET takes advantage of the biochemical differences between normal and malignant tissues, it has been shown to be effective in identifying various types of primary and metastatic tumors.^2,3,7 A major disadvantage, however, is the fact that this method yields only limited information on the exact anatomical location of the lesion.² For this reason, fused PET and CT (PET/CT) scans are now the standard of care and have solved this problem in large part. However, circumstances still exist where PET findings do not have a correlative CT abnormality, making absolute evaluation of these findings difficult without a target for biopsy under cross-sectional imaging guidance.

There are very few studies which describe the use of FDG-PET in allowing image guided biopsies. PET guided biopsies have been used to target areas of high metabolic activity in the prostate and in the brainstem. It has also been shown to be helpful where previous biopsies were negative in prostate cancer and also has improved the diagnostic yield of stereotactic biopsy sampling in infiltrative brainstem lesions. However these biopsies all had corollary imaging with CT or MR.^7,8 As such, our patient presented with a lesion seen only on PET without a CT correlate in which to target for biopsy. PET was utilized to guide biopsy of this lesion.

We believe this the first reported use of PET guidance for biopsy to identify stage IV disease in a patient without obvious distant metastasis elsewhere. This allowed us to properly stage the patient, ultimately making a dramatic difference in treatment modality and prognosis. Our experience shows that PET/CT can not only be used for initial staging and treatment, but PET may also be used to guide biopsy of suspicious or indeterminate lesions identified on staging. This shows the feasibility of biopsy using this technique and may be an important tool in absolute determination of findings obtained on staging studies. PET guided biopsy should be considered in circumstances where indeterminate findings are not accompanied by correlates on cross-sectional imaging, particularly when the results will dramatically alter management of the patient. Although this situation is not common, with increasing utilization of PET/CT in both the staging and follow-up of patients with cancer, it is likely that this will be more common in the future.

Disclosures

The authors have no disclosures or conflicts of interest related to this manuscript.

References

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