Info

HD, Hodgkin's disease; NHL, non-Hodgkin's lymphoma.

HD, Hodgkin's disease; NHL, non-Hodgkin's lymphoma.

both CT and PET, whereas the sensitivity of CT was 65% and that of PET was 92%. An older study including 50 patients compared FDG-PET for staging of HD and NHL to CT.315 The sensitivity and specificity of PET were 86% and 96% for HD and 89% and 100% for NHL. The sensitivity and specificity of CT were 81% and 41% for HD and 86% and 67% for NHL.

In comparison to 67Ga, PET showed better performance than 67Ga, as was reported by Paul et al.316 (the first report on FDG uptake in five patients with lymphomas) and Okada et al.317 Of course, their mechanism of uptake by malignant tissue is based on different principles. FDG, as mentioned before, is incorporated into malignant cells with a high glu-colytic metabolism due to intracellular trapping of FDG phosphate. 67Ga is taken up by malignant cells, lymphoma in particular, probably based on an intracellular transferrin-related transport mechanism. Inside the cells, the tracer is incorporated in lysosome-like granules and shows a slower clearance from malignant as compared with normal tissues.

A study comparing PET and 67Ga evaluated 111 sites of disease in 25 patients with different types of lymphoma at diagnosis and relapse.318 The sensitivity of PET was 96% versus 72% for 67Ga. The false-negative 67Ga studies were attributed to poor detection of low-grade NHL, bone and bone marrow involvement, and lesions smaller than 12 mm in diameter.

The differences in the performance rate of PET, 67Ga, and CT for staging of HD and NHL were evaluated in 50 patients.319 On a site-based analysis, PET showed superior values, 82%, as compared with both 67Ga, 69%, and CT, 68%.

Diagnosis of splenic involvement is difficult using nuclear medicine techniques, because both 67Ga and FDG are physiologically taken up in variable amounts by the normal spleen. Lymphomatous splenic involvement is, as a rule, diffuse, thus increasing the diagnostic challenge. The sensitivity, specificity, and accuracy of PET were 92%, 100%, and 97%, respectively, as compared with 50%, 95%, and 78% for 67Ga320 (Table 33.13).

Buckmann et al.321 found that PET is 10% to 20% more accurate than CT in detecting and staging of malignant lymphoma. They also reported that PET is better than CT in detecting bone marrow involvement and is useful as a guide for bone marrow biopsy.

A change in staging is more likely to result in a change in treatment strategy for lymphoma subtypes in which treatment is given with a curative intent. For example, upstaging from an early (stage I-II) to an advanced stage (III-IV) in HD

or large cell lymphoma will probably result in the selection of a longer course of chemotherapy as the exclusive treatment, as opposed to a shorter course of chemotherapy followed by radiation therapy (Figure 33.6).

A similar upstaging in patients with follicular lymphoma will also influence treatment and follow-up of the disease. Schoder et al.322 demonstrated that PET findings led to a change in the clinical stage in 44% of 46 patients: in patients with NHL and HD, 21% were upstaged and 23% were down-staged. In a recent prospective study of 88 patients with HD, Naumann et al.323 demonstrated a change in staging in 18 patients (20%).

FDG-PET appears to be a noninvasive, efficient, and cost-effective whole-body imaging modality with a high sensitivity, specificity, and accuracy for staging patients with most histologic types of HD and NHL (Figure 33.7). It is generally

FIGURE 33.6. Transaxial PET/CT images obtained with FDG in a patient in the mid-twenties with a new diagnosis of Hodgkin's lymphoma. Intense focal tracer uptake is seen in multiple lymph nodes in the right neck and axillary region. (A) CT scan. (B) Fused PET/CT image. (C) Attenuation corrected PET image. (D) Nonattenuation corrected PET image.

FIGURE 33.6. Transaxial PET/CT images obtained with FDG in a patient in the mid-twenties with a new diagnosis of Hodgkin's lymphoma. Intense focal tracer uptake is seen in multiple lymph nodes in the right neck and axillary region. (A) CT scan. (B) Fused PET/CT image. (C) Attenuation corrected PET image. (D) Nonattenuation corrected PET image.

figure 33.7. (A) Coronal PET/CT images of a 60+-year-old woman with recurrent follicular non-Hodgkin's lymphoma. Intense focal uptake is noted in the right supraclavicular area that is attributed to recurrent disease. (B) Coronal PET/CT images of the patient noted in (A) at 12 weeks after radioim-munotherapy with Bexxar (131I-tositumomab and unlabeled tositumomab therapy). The dramatic decrease in FDG uptake in the right supraclavicu-lar area indicates an excellent response to therapy.

figure 33.7. (A) Coronal PET/CT images of a 60+-year-old woman with recurrent follicular non-Hodgkin's lymphoma. Intense focal uptake is noted in the right supraclavicular area that is attributed to recurrent disease. (B) Coronal PET/CT images of the patient noted in (A) at 12 weeks after radioim-munotherapy with Bexxar (131I-tositumomab and unlabeled tositumomab therapy). The dramatic decrease in FDG uptake in the right supraclavicu-lar area indicates an excellent response to therapy.

TABLE 33.14. Representative literature of PET in monitoring response to treatment of lymphoma.

Herbal Remedy Secret Uncovered

Herbal Remedy Secret Uncovered

Discover How To Use Herbal Medicine Effectively To Heal Away Disease amp illnesses That Most Of The Herbalist Do Not Want You To Know About. If You Have Never Know What Is All About Herbal Medicines amp The Correct Way Of Using Herbs To Build A Healthier Life, Then This Guide Is About To Reveal All Just That.

Get My Free Ebook


Post a comment