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FIGURE 3.1 (a) PET scan coronal projection showing high metabolism in neck muscles, probably sternocleidomastoid muscles (arrow), (b) PET scan coronal projection of the same patient showing resolution of neck metabolism on a PET scan obtained 2 days later using Valium, (c) PET scan axial view showing high metabolism in salivary glands (arrow) and palatine tonsils (dashed arrow), (d) PET scan axial view showing high metabolism in vocalis muscles (short arrow), crico-arytenoid posterior muscle (dashed arrow), and a tumor-bearing lymph node (long arrow).

FIGURE 3.1 (a) PET scan coronal projection showing high metabolism in neck muscles, probably sternocleidomastoid muscles (arrow), (b) PET scan coronal projection of the same patient showing resolution of neck metabolism on a PET scan obtained 2 days later using Valium, (c) PET scan axial view showing high metabolism in salivary glands (arrow) and palatine tonsils (dashed arrow), (d) PET scan axial view showing high metabolism in vocalis muscles (short arrow), crico-arytenoid posterior muscle (dashed arrow), and a tumor-bearing lymph node (long arrow).

jugulodigastric nodes) or with central necrosis are considered abnormal and suspicious for metastasis. The obvious shortcoming to this approach is that the determination of metastasis is based on anatomic criteria alone and excludes the possibility of early nodal metastases, which have failed to enlarge the lymph node.

Standard assessment for distant metastases in head and neck cancer, which is uncommon for patients presenting with a new tumor, can include chest X-ray and liver function tests. CT of the chest or abdomen are used most commonly to evaluate abnormalities found on the preceding two studies.

Second primary disease (either synchronous or metachronous) is an occasional dilemma in head and neck cancer. These lesions are usually in the head and neck, lung, or esophagus. Synchronous lesions are defined as the discovery of a second primary within 6 months of the diagnosis of the first. Metachronous primaries are discovered at an interval greater than 6 months. The standard approach to head and neck cancer used to rule out a second primary has been operative endoscopy (laryngoscopy, bronchoscopy, esophagoscopy). Improved office endoscopy and CT (neck and chest) have resulted in a decrease in operative

endoscopy. The precision of whole body PET may prove useful for synchronous second primary detection and for surveillance for metachronous lesions.

The standard treatment for advanced (stage III and IV) head and neck cancer is surgery followed by postoperative radiation therapy [7]. Which particular advanced stage head and neck tumors to treat with standard surgical resection and which to treat with chemotherapy and radiation can be a challenge. A greater impetus to treat with nonoperative therapy may result if distant metastatic disease is found by FDG PET

B. PET Staging

The ability of PET to change the disease stage by finding undetected malignancy will have treatment implications. The evaluation of stage can be divided into contributions made in assessing the primary tumor, local nodal disease, and metastatic disease. Staging of the primary tumor (T stage) using PET has been described in several published articles [8,9]. In none did PET show an advantage over conventional techniques when the primary was seen by conventional techniques. Primary tumor staging with PET will likely contribute little over conventional staging in most patients with the possible exception of unknown primaries. Standard tumor staging using CT and physical examination with endoscopy will provide more anatomic information that is important to tumor staging than what can be provided by PET. In around 5% of cases, however, the primary may not be identified by standard techniques. Some of these primaries become obvious as the patient is followed over time. Others are thought to regress spontaneously, whereas most are never diagnosed by conventional means. Following these clinical evaluations, PET may identify the unknown primary in about 20-50% of cases as reported by several authors [10-15] (Fig. 3.2). There is some evidence that PET should only be performed after clinical assessment because routine panendoscopy and physical examination will identify some small lesions that may not be seen by PET [16].

Some early evidence suggests that PET may be able to predict radiocurabililty of patients with head and neck cancer. Treatment options for some head and neck tumors include surgery or radiation, and a decision between the two may be based on relative treatment morbidity. A higher level of metabolic activity seems to predict tumor radiocurabililty in a small group reported recently [17]. Larger trials will be needed to assess this finding.

Previous authors have described the high accuracy of FDG PET in local nodal staging of head and neck cancer [8,9,18-23] (Fig. 3.3). All studies have shown PET to be equivalent or superior to anatomic methods of nodal staging (Table 3.1). In a study by Adams et al. [18], about 1400 lymph nodes were sampled in 60 patients, and PET had a 10% advantage over CT, MRI, or US in sensitivity for local

FIGURE 3.2 PET image of a patient with a right neck mass showing squamous cell cancer on biopsy (arrow) and an unknown primary even after review of the CT, physical examination, and negative panendoscopic, biopsies. Thereafter, PET showed a right base of tongue primary medial to the large right lymph node.

nodal disease. The specificity was also 10% higher for PET. The authors showed highly statistically significant differences in the performance of these modalities.

The decision to perform a neck dissection is the most challenging in lower stage primary tumors where there is no clinical evidence of nodal disease. Some of these patients have up to a 30% incidence of occult cervical metastasis. These NO patients can be evaluated by PET, and the advantage over other methods for the detection of disease has also been demonstrated. Myers and Wax [24] showed that PET was more than twice as sensitive as CT in identifying nodal disease in patients with clinically NO necks.

Metastatic disease to distant regions is not common with head and neck cancer. This may relate to an earlier detection of head and neck cancer due to obvious symptoms. It will likely be rare for PET to identify metastatic disease in initial staging that will impact a large proportion of patients due to the low incidence (probably <5%). Imaging of the body with PET is still recommended at initial staging, as this data may be helpful as a baseline evaluation for comparison with later imaging. Subtle uptake from inflammatory lung lesions, for example, can be documented so as to not raise a concern of metastasis on future examinations. Such imaging would also address the issue of second primary disease and possibly reduce the need for other additional testing. There is no additional radiation exposure for the patient, and additional imaging can usually be completed in about 5 min.

In summary, if therapy is based in part on the more accurate staging by FDG PET, patients will have a chance to receive therapy that will be more appropriate. Patients with locore-gional disease that is more extensive than what is identified

Your Metabolism - What You Need To Know

Your Metabolism - What You Need To Know

If you have heard about metabolism, chances are it is in relation to weight loss. Metabolism is bigger than weight loss, though, as you will learn later on. It is about a healthier, better you. If you want to fire up your metabolism and do not have any idea how to do it, you have come to the right place. If you have tried to speed up your metabolism before but do not see visible results, you have also come to the right place.

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