Gallium-67 as a Tumor-seeking Agent in Lymphomas - a Review

A nuclear chocolate box: the periodic table of nuclear medicine

Radioisotopes of elements from all parts of the periodic table find both clinical and research applications in radionuclide molecular imaging and therapy (nuclear medicine). This article provides an overview of these applications in relation to both the radiological properties of the radionuclides and the chemical properties of the elements, indicating past successes, current applications and future opportunities and challenges for inorganic chemistry.

Underperformance of gallium-67 scan is greater in relapse than in initial staging, compared with FDG PET

PURPOSE

The purpose of this study is to evaluate the performance of gallium-67 scan (GS) and F-18 fluorodeoxyglucose (FDG) PET scan in lymphoma staging and recurrence detection by comparing the 2 imaging studies in the same patient.

MATERIALS AND METHODS

A total of 42 patients from the period between July 2002 and May 2006 were included in this study. Of the 42 patients, 6 had Hodgkin disease and 36 had non-Hodgkin lymphomas. All of them underwent one or more FDG PET scans and also underwent corresponding GS performed within 7 days of FDG PET, for staging or detection of lymphoma recurrence. Among the non-Hodgkin lymphoma cases, 18 were diffuse large B-cell lymphoma, 10 were follicular center cell lymphoma, and 8 were of other types. Of the total 46 pairs of imaging performed in these 42 patients, 27 were for staging, and 19 for restaging after recurrence.

RESULTS

In all these studies, FDG PET detected 230 lesion sites, whereas GS detected 85 lesion sites. All of the lesions detected by GS were noted on FDG PET, whereas GS detected only 37.0% of the lesions detected by FDG PET. Among the 27 studies for staging, FDG PET detected 120 lesions, whereas GS detected 68 lesions (56.7%). In the 19 images taken for relapse, FDG PET detected 110 lesions, whereas GS detected only 17 (15.5%).

CONCLUSIONS

FDG PET is superior to GS in staging and detecting all types of lymphoma. The difference is notably more significant in recurrence detection.

Mediastinal seminoma in a patient with Wiskott-Aldrich syndrome

Shortness of breath developed in an 18-year-old man with Wiskott-Aldrich syndrome, and he was found to have a large mediastinal mass. The gallium scan was positive, and biopsy indicated a seminoma. After treatment with four cycles of chemotherapy, the mass completely resolved. Despite severe thrombocytopenia, he required only two platelet transfusions during therapy. Although lymphomas make up the vast majority of mediastinal tumors in patients with Wiskott-Aldrich syndrome, a positive gallium scan should not preclude the diagnosis of seminoma or the need for confirmatory tissue diagnosis. This report shows the possibility of uneventful and successful treatment of malignancy in a patient with Wiskott-Aldrich syndrome and severe thrombocytopenia.

Recurrent lymphoma detected on F-18 FDG coincidence imaging with negative findings on Ga-67 citrate scintigraphy

Ga-67 citrate scintigraphy and computer tomography have been used in tumor staging, to determine disease extent, and for the pre- and post-therapeutic management of Hodgkin's and non-Hodgkin's lymphoma. Today, localization of hypermetabolic tissue using F-18 FDG is beginning to play a role in the staging and restaging of lymphoma. The authors report a case of recurrent Hodgkin's lymphoma in a 31-year-old man detected by F-18 FDG. Findings of the Ga-67 citrate scintigram were negative. Palpable right axillary adenopathy was found on routine physical examination follow-up. Comparison with previous negative findings obtained with Ga-67 citrate was unchanged. However, computed tomography revealed new right axilla lymphadenopathy, prompting further investigation with F-18 FDG SPECT, which showed hypermetabolic activity corresponding to the region of the right axilla involvement. Pathologic examination showed changes indicative of interfollicular recurrence of Hodgkin's lymphoma.

Comparison of fluorine-18 fluorodeoxyglucose positron emission tomography and Ga-67 scintigraphy in evaluation of lymphoma

BACKGROUND

The accuracy of fluorodeoxyglucose positron emission tomography (FDG-PET; dual-head camera with attenuation correction) and Ga-67 scintigraphy was compared to identify disease sites in patients with Hodgkin disease (HD) and intermediate and high-grade non-Hodgkin lymphoma (NHL) at initial diagnosis or clinical recurrence.

METHODS

Fifty-one contemporaneous FDG-PET and Ga-67 scintigraphies were performed on patients with NHL (35 intermediate grade, 3 high grade) or HD (13 patients). Sites of disease were correlated on a site-by-site basis on FDG-PET and Ga-67 images. Tumor-to-background (T/B) ratios were obtained for both techniques. Discordant FDG-PET and Ga-67 findings were correlated with computed tomography findings or clinical evaluation including repeat FDG-PET scans obtained after therapy.

RESULTS

Fluorodeoxyglucose positron emission tomography was positive at all 158 sites in 51 patients compared with 113 sites in 41 positive studies with Ga-67 scintigraphy (single positron emission computed tomography [SPECT] and/or planar images). In 44 patients who had complete Ga-67 SPECT data on all tumor sites, FDG-PET was positive at 126 sites and Ga-67 SPECT was positive at 81 sites. Ga-67 SPECT failed to demonstrate disease at 45 sites (35.7%). In 10 of 44 patients, Ga-67 SPECT completely failed to detect any disease at 22 of 45 sites (17.5%) and partially identified disease sites at 23 of 45 sites (18.2%) in 11 patients regardless of the tumor site and histology. In these patients, the lesions measured between 0.6 and 14.0 cm by CT. Fluorodeoxyglucose positron emission tomography revealed higher stage disease in 13 patients compared with Ga-67 imaging. Tumor-to-background ratios were statistically different between the two techniques with higher ratios obtained with FDG-PET (P < 0.0001).

CONCLUSIONS

In imaging aggressive lymphoma and HD before therapy, FDG-PET has significantly higher site and patient sensitivity than Ga-67 scintigraphy (100% vs. 71.5% and 100% vs. 80.3%, respectively). The change in disease stage by FDG-PET may result in a change in therapy strategy.

Lymphoma: An Update on Evolving Trends in Staging and Management

Because lymphoma frequently manifests as a neck mass, otolaryngologists are often the first to evaluate and diagnose it. Excisional biopsy of lymph nodes generally provides the definitive diagnosis. After diagnosis, however, the otolaryngologist's involvement generally wanes as subsequent treatment of the patient is provided by an oncology team. Nevertheless, it is important for the otolaryngologist to be familiar with current concepts in the comprehensive evaluation and treatment of lymphoma patients. This knowledge allows us to participate in and facilitate timely testing, which helps avoid undue delays between the documentation of physical findings and the initiation of treatment. Otolaryngologists also need to be up to date on recent developments in the treatment of lymphomas in order to be able to answer questions regarding staging and prognosis, to make the proper referrals, and to help our patients understand current controversies and treatment practices.

Gallium scan in the evaluation of post chemotherapy mediastinal residual masses of aggressive non-Hodgkin's lymphoma

Optimal evaluation of residual masses of non Hodgkin's lymphomas (NHL) after chemotherapy is of major importance, and gallium scan (GS) is routinely used for this purpose, particularly for mediastinal sites. However, sensitivity and specificity of GS in this setting has been diversely appreciated and needs to be more accurately defined especially if radiotherapy is not planned. A retrospective analysis selected all the patients treated in a single institution for aggressive NHL who presented a residual mass in the mediastinum after chemotherapy and who were evaluated by GS. The value of GS for distinguishing true complete responses (CR) from partial responses (PR) was analyzed in patients who were either submitted to resection of their residual mass or followed up without further treatment after GS. A residual mass with mean perpendicular diameters measuring 4.1 cm x 2.8 cm was found in 42 patients and was GS positive in 8 cases and negative in 34 cases. After GS, radiotherapy was delivered to 10 patients, but 12 patients underwent resection of their residual mass and 20 were followed up without further treatment. In the patients who did not receive radiotherapy, 3 false positive and 6 false negative GS results were disclosed. The specificity and the sensitivity of GS were 88% and 25%, and its positive predictive value and negative predictive value 40% and 78%, respectively. GS was not sufficiently reliable to evaluate post chemotherapy residual masses. Surgical resection of residual masses should be considered particularly in young patients. Patients in true CR should be spared pointless radiotherapy and its late side effects, while patients in PR may benefit from further intensified chemotherapy followed by radiotherapy.