ABSTRACT
Technetium-99m phytate [[99m]Tc-ph] is a readily available radiopharmaceutical and has been suggested as a suitable agent for sentinel lymph node [SLN] detection. In this study, the diagnostic accuracy and false-negative rate of radionuclide SLN mapping using [99m]Tc-ph were investigated. Forty three women [mean age 52.3 years, range 31-74 years], who all had been diagnosed with breast cancer were enrolled in the study. All patients had no palpable axillary lymph nodes and had not undergone exploratory tumor resection or any drug treatment, previously. [99m]Tc-ph was injected peri-tumorally at four sites. Following SLN scintigraphic imaging, the patients were operated. Intraoperatively SLN were detected by a scintillation probe and a blue dye technique. Modified radical mastectomies with radical axillary dissection were performed with excision of the lymph nodes, to evaluate the accuracy of the SLN technique. Intraoperative scinti-mapping identified SLN in 40 of the 43 patients [detection rate: 93%]. Scintigraphically, none of the patients had internal mammary drainage or contralateral axillary involvement. The blue dye detection rate in 23 patients under study was 87% and all lymph nodes detected by the blue dye technique were also detected as "hot" spots in the lymphoscintigraphy. Using pathology as the gold standard, the sensitivity and negative predictive value of scintigraphic lymphatic mapping in detection of SLN by [99m]Tc-ph were 90% and 90.9%, respectively. The same values for blue dye lymphatic mapping were 84.6% and 77.7%, respectively. [99m]Tc-ph used for SLN mapping is readily available, has low cost and gives better results than the blue dye technique. Long-term follow-up is required to assess accurately the incidence of failure in patients with negative SLN and the overall diagnostic accuracy and efficacy of the SLN mapping using [99m]Tc-ph as the radioactive tracer
Subject(s)
Humans , Female , Lymph Nodes/diagnostic imaging , Phytic Acid , Organotechnetium Compounds , LymphographyABSTRACT
Bone scanning using the 99mTc-phosphate analogs is an established diagnostic modality and a commonly requested radioisotope examination for a variety of pathologies involving the skeleton, such as osteomyelitis, bony metastases, and occult fractures. The bone scan is one of the most commonly requested procedure in most nuclear medicine department. The images show areas of increased and decreased activity usually related to the bone turnover. The bone scan is interpreted by evaluating the pattern of radioactive localization in the skeleton and identifying areas of increased uptake [hot spots] or, less frequently, decreased or absent activity [1]. Unfortunately, the findings are most often very nonspecific and do not tell us the exact underlying cause of the abnormal activity. A variety of factors may change the normal distribution of bone-seeking radiopharmaceuticals. Although most of the times these areas of abnormal radiotracer activities are due to true pathologic bone states, however, it is not infrequent that they are caused by technical errors such as urinary contamination, nonuniformity of gamma camera, and attenuation of activity by foreign bodies. These artifactual causes warrant careful attention to prevent unnecessary interventions. In certain conditions, nonosseous structures other than the urinary tract are seen on the bone scan. For example, there may be localized muscle uptake, such as myositis ossificans, or localization in a pleural effusion. Such serendipitous findings may constitute welcome diagnostic information [1]. On the other hand, soft-tissue uptake may at times hamper interpretation of the study by bringing in artifacts that degrade the quality of the images. Therefore, recognition of patterns of nonbony uptake is important for correct identification of artifacts and accurate interpretation of the scan [1]. This paper presents two cases of artifactual causes of odd radiotracer activity in bone scans. In both cases the artifact is at least somewhat related to an indwelling catheter