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Monoclonal antibody 19-9 (mAb 19-9) against human colon adenocarcinoma was conjugated with gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) and used as a contrast agent in nuclear magnetic resonance (NMR) in an effort to improve tumor target selectivity in nude mice. The data indicate that Gd-DTPA-mAb 19-9 in solution decreased the T1 relaxation of water protons at 90 MHz in direct proportion to the gadolinium concentration, and this effect was greater than in Gd-DTPA solutions. T1 relaxation time at 90 MHz, measured in tumors removed from nude mice 24 hr after injection of GdDTPA-mAb 19-9 (Gd, 20 pumol/kg; 16 DTPA molecules per mAb molecule), was significantly decreased (by 15%) as compared with the control group. Similar results were obtained in tumors from mice injected with GdDTPA-mAb 19-9 solutions in which Gd was used at 2, 6, or 10 jsmol/kg (16 DTPA molecules per mAb molecule). These doses are lower than those commonly used for GdDTPA (10-100 j#mol/kg) as contrast agent. Tumor localiztion by the Gd-DTPA-mAb 19-9 complex containing radioactive Gd (0.3 IACi/tg of ls3Gd) to confirm scintigraphy revealed significant concentrations of the complex (5% of the injected dose per gram of tissue) in the tumor. Scan images recorded in planar scintigraphy at day 5 showed good visualization of tumors.Nuclear magnetic resonance (NMR) proton imaging provides sharp contrast between tissues based on their intrinsic T1 and T2 relaxation times when varied pulse sequences are used. By exploiting the differences in relaxation times, images have been produced that provide previously unobtainable anatomic and physiologic information. Early investigators felt that differences in relaxation times between tumors and normal tissue made contrast agents unnecessary. However, despite this intrinsic tissue contrast, the absence of oral or intravenous contrast agents has proved disadvantageous (1, 2). Various intravenous and oral contrast agents have been proposed, including paramagnetic metal ions and their chelates and complexes (3, 4). Recently, attention has focused on gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA), a complex that produces a marked reduction in the proton relaxation ratio in vitro and in vivo and appears to have minimal acute toxicity in imaging doses (5, 6). One approach to increasing the specificity of NMR image contrast is to use paramagnetic contrast agents coupled with a monoclonal

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BACKGROUNDPrevious reports have shown that regional lymph node involvement in patients with early‐stage breast carcinoma can be evaluated by resection of axillary sentinel lymph nodes (ASLN). Axillary lymphadenectomy may be unnecessary in the absence of ASLN involvement. In the current study, the authors compared the results of ASLN resection in patients with lobular invasive carcinoma (LIC) with the results from patients with ductal invasive carcinoma (DIC) in terms of detection rates and false‐negative rates.METHODSFor ASLN detection, technetium 99m sulfur‐colloid and patent blue were injected around the tumor. Each patient underwent both ASLN resection and complete axillary lymphadenectomy. Detection rates and false‐negative rates were evaluated in patients with LIC and in patients with DIC.RESULTSTwo hundred forty‐three patients with invasive, early‐stage breast carcinoma were enrolled in the study (208 patients with DIC and 35 patients with LIC). The median patient age, pathologic tumor size, hormone receptor status, and rates of involved lymph nodes were equivalent for both groups. ASLN detection and false‐negative rates did not differ for patients with LIC and patients with DIC.CONCLUSIONSThe ASLN detection rate was not dependent on the pathologic type of invasive carcinoma. Pathologic examination of ASLN in patients with LIC and in patients with DIC predicted axillary lymph node status with the same predictive value in terms of lymph node metastasis. For patients with LIC, ASLN examination overestimated the rate of micrometastasis as diagnosed by immunohistochemical techniques. These results will require confirmation in larger studies. Cancer 2004;100:935–41. © 2004 American Cancer Society.