The three-dimensional localization of internal mammary lymph nodes by radionuclide lymphoscintigraphy.

In breast cancer patients, radiation therapy planning must account for individual anatomy to ensure optimal coverage of tumor and internal mammary nodes. To achieve this, three-dimensional radionuclide lymphoscintigraphy (RNLS) was performed in 167 patients by obtaining two images of the nodes using a 30-degree slant hole collimator rotated 180 degrees between images. Analysis of 768 nodes (mean 4.6/patient) visualized from the level of rib 1 through interspace 5 was performed. The number of nodes seen was not a function of patient age. Cross-communication to the contralateral node chain occurred in 13.8% of cases. Eighty-two percent of nodes were located near the first three ribs and interspaces; 23% were located beyond 3.0 cm from the mid-sternal line. At the level of the radiation beam match line (second rib or interspace), 4.5% of nodes were deeper than 3.0 cm. From rib 3 through interspace 5, 3.9% were deeper than 3.0 cm. Using an idealized tangential field, at least one node would have been missed in 16.2% of patients. Three-dimensional RNLS allows definition and localization of normal sized nodes and ensures that radiation therapy portals can be tailored for each individual under treatment.

Thallium-201 brain tumor imaging: a comparative study with pathologic correlation.

In patients with gliomas who were stable or improving, we noted a disparity between clinical status and computed tomography (CT) brain scan results. To elucidate this finding, 29 patients were sequentially scanned with 2.0 mCi of 201Tl (5-30 min), 20 mCi [99mTc]gluceptate (GH) (3-4 hr) and 7-10 mCi 67Ga (48-72 hr). A total of 198 images were obtained. A set of three scans at a midpoint in follow up was selected for analysis. Seven patients who died had neuropathologic data available; brain sections were reconstructed to match radionuclide views without knowledge of image results. In the seven patients with autopsy data, 201Tl offered the most accurate correlation with viable tumor. Gallium-67 gave similar results in patients not receiving steroids. Technetium-99m GH scans could not allow differentiation between tumor, necrosis, and edema. Similarly, the CT scan could not routinely differentiate between fibrotic, nonfibrotic, necrotic, and neoplastic tissue. In the 22 patients without autopsy data, 201Tl scans commonly showed smaller and more focal abnormal uptake when compared with [99mTc]GH and 67Ga scans. Thallium-201 scans more accurately reflect viable tumor burden than other radionuclide studies of primary brain tumors, are minimally affected by concomitant steroid administration, can be performed immediately following tracer administration, and complement the anatomic data obtained from CT scans.