Position paper on the development of a middle level provider in nuclear medicine: the nuclear medicine practitioner.

The development of an educational program and credentialing structure to support and recognize an advanced level of the practice of nuclear medicine technology is now underway. This work parallels the efforts in many, if not most, health care disciplines as they seek to achieve the twin goals of developing enhanced career paths and providing the best possible patient care in an environment where science and technology can run roughshod over concepts taught in the classroom a mere decade ago. Education is key to both goals. A master's level degree in nuclear medicine technology, coupled with an advanced practice credential recognizing both the educational achievement and a level of clinical expertise, will give nuclear medicine practitioners the knowledge and the right to practice their profession at a high level of autonomy, leading to more efficient and higher quality health care services. To that end the following position paper was prepared by members of the Advance Practice Task Force of the SNMTS and presented to the SNMTS Executive Council and the SNM Board of Directors. In June 2005, the executive council and the board of directors approved a resolution supporting the establishment of a middle level provider in nuclear medicine known as the nuclear medicine practitioner.

Imaging taxane-induced tumor apoptosis using PEGylated, 111In-labeled annexin V.

UNLABELLED: 99mTc-Labeled annexin V has been used for the imaging of tumor apoptosis induced by chemotherapy. However, owing to the short half-life of annexin V, multiple injections of the radiotracer are necessary to capture the peak apoptotic activity. In this study, we evaluated the imaging properties of an (111)In-labeled, long-circulating annexin V. METHODS: Both polyethylene glycol (PEG) and the metal chelator diethylenetriaminepentaacetic acid (DTPA) were simultaneously introduced to annexin V or ovalbumin through the use of a heterofunctional PEG precursor. Imaging studies were performed in mice bearing subcutaneously inoculated human mammary MDA-MB-468 tumors. The mice were treated with poly(L-glutamic acid)-paclitaxel, monoclonal antibody C225, or a combination of poly(L-glutamic acid)-paclitaxel and C225, followed by intravenous injection of (111)In-DTPA-PEG-annexin V. Images were acquired 48 h after the injection of the radiotracer. Autoradiography and TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling) staining were performed on adjacent tumor slices for the localization of apoptotic cells. The imaging properties of unPEGylated annexin V and PEGylated ovalbumin were also determined to permit assessment of the specificity of (111)In-DTPA-PEG-annexin V. RESULTS: Tumor apoptotic index increased from 1.67% +/- 0.31% at baseline to 7.60% +/- 0.72% and 11.07% +/- 1.81%, respectively, 4 d after treatment with poly(L-glutamic acid)-paclitaxel or combined poly(L-glutamic acid)-paclitaxel and C225. Tumor uptake (percentage of injected dose per gram of tumor [%ID/g]) of PEGylated (111)In-DTPA-PEG-annexin 4 d after treatment was significantly higher in tumors treated with poly(L-glutamic acid)-paclitaxel (10.76 +/- 1.38 %ID/g; P = 0.001) and with combined poly(L-glutamic acid)-paclitaxel and C225 (9.84 +/- 2.51 %ID/g; P = 0.029) than in nontreated tumors (6.14 +/- 0.67 %ID/g), resulting in enhanced visualization of treated tumors. (111)In-DTPA-PEG-annexin V distributed into the central zone of tumors, whereas (111)In-DTPA-annexin V was largely confined to the tumor periphery. Furthermore, uptake of (111)In-DTPA-PEG-annexin V by tumors correlated with apoptotic index (r = 0.87, P = 0.02). Increase in tumor uptake of the nonspecific PEGylated protein (111)In-DTPA-PEG-ovalbumin was also observed after poly(L-glutamic acid)-paclitaxel treatment (55.6%), although this increase was less than that observed for (111)In-DTPA-PEG-annexin V (96.7%). CONCLUSION: Increased uptake of and improved visualization with (111)In-DTPA-PEG-annexin V in solid tumors after chemotherapy are mediated through both specific binding to apoptotic cells and nonspecific retention of macromolecular contrast agents in the tumors. (111)In-Labeled, PEGylated annexin V may be used to assess tumor response to chemotherapy.

Radiation dosimetry of 99mTc-labeled C225 in patients with squamous cell carcinoma of the head and neck.

UNLABELLED: This study assessed the radiation dosimetry of 99mTc-labeled ethylene dicysteine (EC) C225 (EC-C225), a promising radioligand for functional tumor imaging. METHODS: Whole-body scanning was performed on 6 patients with head and neck squamous cell carcinoma up to 24 h after administration of 99mTc-EC-C225. Alternate patients who had been randomized to receive C225 in a phase III trial received 99mTc-EC-C225 before their 20-mg test dose or after their 400 mg/m2 loading dose of unlabeled C225 (patients 1/3/5 and 2/4/6, respectively). Radiation dosimetry was assessed using the MIRD method. RESULTS: The critical organ was the kidney, with an average radiation-absorbed dose for all 6 patients of 0.0274 mGy/MBq. The average total-body absorbed dose was 0.0022 mGy/MBq (0.243 cGy/1,110 MBq). CONCLUSION: The new radiopharmaceutical 99mTc-EC-C225 appears to have reasonable dosimetric properties for a diagnostic nuclear medicine agent. Correlation of the imaging results with clinical findings is the next step.

Acquisition parameters for oncologic imaging with a new SPECT/multislice CT scanner.

INTRODUCTION: Single photon emission computed tomography/computed tomography (SPECT/CT) delivers in a single imaging modality the functional-metabolic information from the SPECT image, combined with the detailed anatomical information from a diagnostic quality CT scanner. METHOD: In this review, we provide the details for the acquisition, processing, and display of the SPECT, as well as the CT, and the fused SPECT/CT images, with one of the newest devices that combines a dual-headed gamma camera with a multislice CT scanner. Also, we go over the performance characteristics, including the planning and installation requirements for this type of scanners. In addition, we describe what are the current and feasible near-future applications of this new and exciting hybrid imaging modality. DISCUSSION: The ability to combine an optimized state-of-the-art SPECT image, with resolutions down to 5 mm, with a diagnostic quality CT image-using slices as thin as 1.25 mm-provides a diagnostic advantage that potentially can deliver a more convenient and faster diagnosis, with clinical implications in a significant percentage of patients. This imaging technique has been investigated in a wide range of studies for the oncologic patient, including but not limited to bone scintigraphy, (111)In-pentetreotide scintigraphy, lymphoscintigraphy, (67)Ga and labeled leukocyte infection imaging, (131)I-metaiodobenzylguanidine, parathyroid scintigraphy, (131)I diagnostic scintigraphy, and (111)In ProstaScint, and for planning of radionuclide therapy. CONCLUSION: Therefore, this evolving and exciting imaging modality will continue to grow and define its place as an integral part of the evaluation of the cancer patient.

The safety of lymphatic mapping in pregnant breast cancer patients using Tc-99m sulfur colloid.

This investigation was undertaken to assess the risk to the embryo/fetus associated with sentinel lymph node biopsy and lymphoscintigraphy of the breast performed in pregnant patients. Approximately 92.5 MBq (2.5 mCi) of filtered Tc-99m sulfur colloid was injected peritumorally the day before surgery in two nonpregnant women with breast cancer. The whole-body distribution of the radiopharmaceutical was evaluated using a gamma camera 1 hour after injection. We then calculated the absorbed dose to the embryo/fetus for three theoretical extreme scenarios of biodistribution and pharmacokinetics: 1) all of the injected radiopharmaceutical remains in the breast and is eliminated only by physical decay; 2) all of the injected radiopharmaceutical is instantaneously transported to the urinary bladder, where it remains and is eliminated only by physical decay; and 3) the injected radiopharmaceutical behaves as though it were administered intravenously, that is, it has the biodistribution and pharmacokinetics of Tc-99m sulfur colloid injected for a liver/spleen or bone marrow scan. The fetal radiation absorbed dose was then estimated for two Tc-99m dosages: 18.5 MBq (0.5 mCi) and 92.5 MBq (2.5 mCi). The Medical Internal Radiation Dosimetry (MIRD) program was used to estimate the absorbed doses to the embryo/fetus for the first two scenarios. Published data were used to calculate the doses for the third scenario. A single breast is not among the source organs in the MIRD program, so the heart was used as a surrogate in the first scenario. In the two breast cancer patients, whole-body gamma-camera images obtained 1 hour after radiopharmaceutical injection revealed no radioactivity except in the vicinity of the injection site. In the theoretical scenarios, with 92.5 MBq, the highest absorbed doses to the embryo/fetus were as follows: scenario 1, 7.74 x 10(-2) mGy at 9 months of pregnancy; scenario 2, 4.26 mGy during early pregnancy; and scenario 3, 0.342 mGy at 9 months of pregnancy. The maximum absorbed dose to the fetus of 4.3 mGy calculated for the worst-case scenario is well below the 50 mGy that is believed to be the threshold absorbed dose for adverse effects. Thus breast lymphoscintigraphy during pregnancy appears to present a very low risk to the embryo/fetus.