Lymphoma is a general term that refers to a group of malignancies originating in the lymphoid tissue, including Hodgkin's disease (HD) and non-Hodgkin's lymphoma

(NHL).302 The first evaluations of PET for staging in large cohorts of patients with lymphoma were performed by Moog et al.303'304 (mixed populations with HD and NHL). For nodal staging, Moog et al.303 evaluated 60 patients with CT and PET and verified discordant results by biopsy whenever possible. A total of 160 nodal regions were positive by both modalities, and 25 were positive by PET alone. Nine of these were verified histologically, and PET was true positive in 7 cases and false positive in 2 cases. Six regions were positive by CT only, and in the 3 in which verification was obtained, the CT result was false positive. There was a change in management in 10% to 15% of the patients.

For extranodal staging, Moog et al.304 also evaluated 81 patients. Forty-two disease sites were detected by both modalities, and PET detected an additional 24 sites, of which 15 were verified pathologically, including 9 sites in bone marrow, 3 in the spleen, and 2 elsewhere, and in 14 sites PET was true positive. Six of 7 lesions detected only by CT were verified, and 5 of these were false positive.

FDG-PET was found to be of value in the diagnosis of HD and aggressive NHL.305,306 It is generally accepted that FDG-PET may have a role in diagnosis and staging of low-grade follicular NHL. For other subtypes of low-grade lymphoma (small cell lymphocytic and probably mantle cell lymphoma), it seems that FDG-PET has no value for staging and follow-up.305,307 Similar discouraging results have been demonstrated in a small group of patients with follicular lymphoma of the duodenum.308 In contrast, marginal zone B-cell lymphoma, an entity that was initially considered to originate from mucosa-associated lymphoid tissue (MALT) lymphoma, but in recent reports is classified as a distinctive histologic type, was shown to take up FDG only in the involved lymph nodes.

From the studies of Moog et al.309 and Carr et al.,310 it appears that both PET and iliac crest biopsy should be performed to stage the bone marrow. It is probable that some patients with diffuse involvement have homogeneous uptake on PET, whereas some patients with focal involvement are missed by random biopsy. FDG-PET can be useful in guiding the biopsy to a site of active disease.

An additional study evaluated FDG-PET as a predictor of prognosis. Aggressive and treatment resistant tumors showed a trend toward higher uptake of FDG, with an inverse relationship between the survival rate of patients and the degree of FDG uptake.311

The complementary role of FDG-PET to conventional staging of 45 patients with newly diagnosed HD and NHL was investigated by Delbeke et al.312 In addition to the positive impact of PET, these authors report that false-negative FDG imaging understaged 3 patients (7%), including 2 patients with low-grade NHL and 1 with HD. They concluded that FDG-PET is an efficient method for staging of lymphoma but should be used in conjunction with conventional staging as a complementary modality.

Recently, Hong et al.313 evaluated the clinical value of FDG-PET for the staging of malignant lymphoma. The sensitivities and specificities for detection of nodal involvement for PET, CT, and 67Ga scanning were determined to be 93.3%, 98.9%, and 25.8%, and 100%, 99.1%, and 99.8%, respectively. In detecting extranodal lymphoma, the sensitivities and specificities of the PET, CT and 67Ga scanning were 87.5%, 87.5%, and 37.5%, and 100%, 100%, and 100%, respectively. Sasaki et al.314 showed a specificity of 99% for

TABLE 33.13. Representative recent literature of PET findings in lymphoma.
A Disquistion On The Evils Of Using Tobacco

A Disquistion On The Evils Of Using Tobacco

Among the evils which a vitiated appetite has fastened upon mankind, those that arise from the use of Tobacco hold a prominent place, and call loudly for reform. We pity the poor Chinese, who stupifies body and mind with opium, and the wretched Hindoo, who is under a similar slavery to his favorite plant, the Betel but we present the humiliating spectacle of an enlightened and christian nation, wasting annually more than twenty-five millions of dollars, and destroying the health and the lives of thousands, by a practice not at all less degrading than that of the Chinese or Hindoo.

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