Tc-99m(V) DMSA imaging. A new approach to studying metastases from breast carcinoma.

Combined Tc-99m MDP skeletal imaging and Tc-99m(V) DMSA whole body scans to detect metastases were performed during the follow-up of 30 patients who underwent surgery for breast carcinoma. Eight patients had normal Tc-99m MDP and Tc-99m(V) DMSA scans and were declared free of metastatic disease, further confirmed by no change in symptomatology over a 1-year follow-up period. Twenty-two patients had positive Tc-99m MDP scans with varied skeletal involvement. Tc-99m(V) DMSA scans showed matched areas of increased radiotracer concentration in bony metastases in 20 of these patients. Tc-99m(V) DMSA concentration was not seen in traumatic vertebral collapse or in coexistent osteoarthritic disease in vertebral metastatic involvement. Interestingly, Tc-99m(V) DMSA showed increased concentration in brain and liver metastases. Pentavalent Tc-99m(V) DMSA appears useful for detecting skeletal and soft-tissue metastases in breast carcinoma, and can improve the specificity of Tc-99m MDP bone scans in screening for bone metastases.     

99mTc-(V)DMSA scintimammography in the assessment of breast lesions: comparative study with 99mTc-MIBI

The purpose of this study was to evaluate and compare the diagnostic accuracy of pentavalent technetium-99m dimercaptosuccinic acid [99mTc-(V)DMSA] and 99mTc-methoxyisobutylisonitrile (MIBI) in the detection of primary breast cancer and metastatic lymph node involvement, and in the clarification of cases with indeterminate mammograms. Forty-one women (mean age+/-SD 55+/-7 years) referred for a suspicious breast lesion on physical examination and/or an abnormal mammogram underwent MIBI and (V)DMSA scintimammography (SMM) at separate sessions (48-h interval). Lateral prone and anterior supine images were obtained at 10 and 60 min after administration of 740-925 MBq of each tracer, in the arm contralateral to the breast lesion. The ipsilateral axillary region was also included in the field of view. The results of SMM and mammography were compared with histological findings. Breast cancer was histologically confirmed in 26 patients (mean diameter+/-SD 2.87+/-1.5 cm). Benign lesions were found in 15 patients (mean diameter+/-SD 2.04+/-2.7 cm). Mammography was definitely positive in 23/26 patients with breast cancer and indeterminate in 3/26 (sensitivity 88.4%). In benign lesions, mammography was true negative in 5/15 cases and indeterminate in 10/15 (specificity 33.3%). Both MIBI and (V)DMSA SMM detected 23/26 breast cancers (sensitivity 88.4%) and were true negative in 14/15 (specificity 93.3%). T/B ratios for breast cancer in MIBI and (V)DMSA scans were similar, and significantly higher than for benign lesions. MIBI correctly diagnosed 12/13 and (V)DMSA 11/13 cases in which the findings of mammography were indeterminate. In addition, (V)DMSA detected seven of eight cases of in situ ductal carcinoma (DCIS) associated with infiltrating carcinomas, while MIBI detected only two of these eight cases. (V)DSMA was also diffusely concentrated in benign lesions complicated by epithelial hyperplasia. Metastatic lymph node involvement was successfully imaged in 15/19 patients with metastatic disease by both agents (sensitivity 78.9%), while true-negative scans were observed in 19/22 (specificity 86.3%) patients with benign or malignant tumours without lymph node metastases. Linear regression analysis revealed a high coefficient of correlation between the (V)DMSA and the MIBI T/B ratios (r=0.8 P<0.001). We conclude that both (V)DMSA and MIBI show an excellent ability to detect breast cancer and its lymph node metastases. (V)DMSA also has a tendency to be diffusely and more intensely localised than MIBI in pre-invasive lesions, such as DCIS or epitheliosis, which are at risk of developing into malignancies. (V)DMSA could therefore provide a useful tool in the diagnosis of such lesions and possibly modify a predefined surgical plan. Finally, we believe that both tracers could offer an alternative method for elucidating nondiagnostic mammograms.     

The role of Tc-99m (V) DMSA scintigraphy in the evaluation of superscan on bone scintigraphy

PURPOSE: This study evaluated the biodistribution of Tc-99m (V) DMSA in patients with superscans on bone imaging and defined its role in differentiating the underlying cause. METHODS: Nine patients (five with metastatic and four with metabolic bone disease) with classical superscans were entered into the study. All patients had the necessary radiologic and biochemical studies and a final diagnosis was reached accordingly. Tc-99m (V) DMSA scintigraphy was performed 1 week after Tc-99m MDP whole-body bone imaging. RESULTS: In four of five patients with widespread skeletal metastases, Tc-99m (V) DMSA scan showed diffusely increased bone uptake. In the remaining patient, the Tc-99m (V) DMSA scan showed a normal distribution pattern. All patients with metabolic bone disease had increased bone uptake on Tc-99m (V) DMSA scans. CONCLUSION: Tc-99m (V) DMSA shows increased bone uptake in patients having a superscan appearance in metastatic or metabolic bone disease. Tc-99m (V) DMSA imaging may play a role in the evaluation of patients with equivocal bone scan findings for a superscan.     

Tc-99m(V) DMSA uptake in cardiac amyloidosis.

Tc-99m(V) DMSA scintigraphy was performed on two patients with primary cardiac amyloidosis. Scintigraphy performed (after radionuclide administration) showed accumulation in the myocardium.     

Tc-99m pentavalent DMSA scintigraphy in myelofibrosis detection

In a 62-year-old man with medullary carcinoma of the thyroid, a postoperative Tc-99m dimercaptosuccinic acid [(V) DMSA] study was requested. In the Tc-99m (V) DMSA scan. no abnormalities, indicating local recurrence or metastatic disease, were observed. However, there was increased uptake in the spleen and liver and significantly diffusely increased uptake in the bone marrow. The patient also had a history of myelofibrosis and these findings appear to have been the result of this pathology.     

The role of Tc-99m (V) DMSA scintigraphy in the diagnosis and follow-up of lung cancer lesions

Objective To define the role of Tc-99m (V) dimercaptosuccinic acid (DMSA) scanning in the detection of lung cancer (LC) and its metastases, and monitoring the response of LC lesions (LCL) to chemo/radiotherapy (TH). Methods Tc-99m (V) DMSA whole-body scans, planar thorax views, and thorax Single-photon emission computed tomography (SPECT) images were obtained both 30 min (early) and 5 h (late) after Tc-99m (V) DMSA administration in 12 small/nonsmall cell LC patients (11 men, 1 woman; mean age 59 years). Five patients also had bone scans. The same scintigraphic protocol was performed in 7 of 12 patients, 3 weeks after first-line TH. TH response was evaluated visually in all LCL and semiquantitatively in primary tumors (PT) of six patients, by comparing the tumor uptake ratios (TUR) of pre-TH and post-TH Tc-99m (V) DMSA SPECT [TUR = mean counts of region of interests (ROI) in PT/mean counts in contralateral ROI]. In seven patients, a 6-month survival was determined. Results Tc-99m (V) DMSA accumulated in 34 LCL (11 PT, 19 bone metastases, 1 suprarenal mass, 1 axillary node, 2 supraclavicular nodes). A total of 11 patients displayed Tc-99m (V) DMSA uptake in LCL and one patient did not show uptake. In six patients, SPECT imaging showed deeply located PT in the lung parenchyma better than planar views. In five patients, both planar and SPECT views revealed peripherally located PT in the lungs. Early scans showed 18 LCL and late scans displayed all the LCL. Nine bone metastases on pre-TH Tc-99m (V) DMSA scans revealed matched areas of increased Tc-99m methylene diphosphonate (MDP) uptake on bone scans; six bone metastases were additionally detected on Tc-99m (V) DMSA scans when compared with bone scans, and four bone metastases on Tc-99m (V) DMSA scans could not be compared with bone scans because bone scan was not performed. In one patient, Tc-99m (V) DMSA scans became positive for bone metastases on post-TH later than the bone scans for some of the bone metastases. Neither planar nor SPECT imaging showed mediastinal lesions defined on thorax CT in nine patients. On TH monitoring, 17 LCL showed diminished Tc-99m (V) DMSA uptake, one disappeared, four were unchanged, three displayed increased uptake, and five new lesions were established. Of the six patients, TUR in PT increased in two (one survived), decreased in one (exitus), was unchanged in two (two exitus) on post-TH scans, and PT totally disappeared in one (survived) patient. Conclusions Tc-99m (V) DMSA scans are useful in detecting LCL, except for those around the blood pool regions, making it a promising modality to monitor TH response. Obtaining a single fifth hour late Tc-99m (V) DMSA scan is appropriate. SPECT should be applied to all patients for the detection of deeply located lesions.     

A comparison of the tumor-seeking agent Tc-99m(V) dimercaptosuccinic acid and the renal imaging agent Tc-99m dimercaptosuccinic acid in humans

Being aware of the ideal nuclear properties of Tc-99m, our interest has been focused on the design of the (+5) oxidation state Tc-99m(V) dimercaptosuccinic acid (Tc(V)-DMSA) as a tumor-seeking agent. Tc-99m(V) DMSA holds a TcO4(3-) core and, like PO4(3-), has excellent characteristics for tumor uptake, but has a different distribution than the well-known renal scanning agent, Tc-99m DMSA. The differences in chemical behavior of Tc-99m(V) DMSA and Tc-99m DMSA are discussed. Three cases in which neoplasms were studies with Tc-99m(V) DMSA and Tc-99m DMSA are presented. Tc-99m DMSA and Tc-99m(V) DMSA, having a common ligand and tracer but, with the metal ion core in a different oxidation state, the uptake characteristics are altered markedly.     

Images of liposarcoma using technetium-99m bleomycin and technetium (V)-99m DMSA

The effectiveness of Tc-99m bleomycin (BLM) and Tc(V)-99m DMSA are compared with that of Ga-67 citrate, which is currently the most widely used agent. In four patients with lipomatous tumors, the clinical significance of tumor imaging with each of these three agents is discussed and compared. Results indicate that both Tc-99m BLM and Tc(V)-99m DMSA are superior in detecting the extension or localization of liposarcomas.     

Analogy between tumor uptake of technetium(V)-99m dimercaptosuccinic acid (DMSA) and technetium-99m-MDP

Sixty patients with a variety of malignant tumors were examined with Tc-99m(V) dimercaptosuccinic acid (DMSA) prepared by modification of a commercially available DMSA kit. Significant uptake of Tc-99m(V)-DMSA was observed in a number of tumors, offering additional clinically useful information. In the majority of cases in this study, however, the benefit of the Tc-99m(V)-DMSA image was limited because of low sensitivity. The most striking observation was the similarity between the tumor concentration of Tc-99m(V)-DMSA and the Tc-99m-MDP uptake in the tumor on the regular bone image. Therefore, patients with Tc-99m-MDP uptake in nonosseous tumor sites on the bone scan may be suitable candidates for tumor imaging with Tc-99m(V)-DMSA.     

Pentavalent technetium-99m DMSA uptake in pseudofractures of osteomalacia

Tc-99m MDP and Tc-99m (V) DMSA images are described from a 49-year-old woman with chronic renal insufficiency complicated by osteomalacia. Clinical, biochemical, and radiologic bone profiles were compatible with osteomalacia. Osteomalacia is a condition associated with disorders in which mineralization of the organic matrix is defective. All bone lesions visualized with Tc-99m MDP also showed increased uptake of Tc-99m (V) DMSA. Tc-99m (V) DMSA accumulation has been reported in many malignant and some benign conditions. Pseudofractures in osteomalacia could be included in the spectrum of benign lesions that accumulate Tc-99m (V) DMSA.     

The comparison of dual phase Tc-99m MIBI and Tc-99m MDP scintimammography in the evaluation of breast masses: Preliminary report

The aim of this prospective study was to determine the diagnostic value of Tc-99m MDP scintimammography (SMG) for the detection of breast cancer in patients with breast masses and to compare the results with Tc-99m MIBI scintimammography. Twenty patients, categorized as suspicious, positive or benign for breast cancer according to the mammographic findings were included in the study. Dual phase Tc-99m MIBI and Tc-99m MDP SMG were performed in the prone lateral position within 5 days of each other. Although early and late Tc-99m MIBI SMG showed equal (90.4%) sensitivity, the specificity of late Tc-99m MIBI (87.5%) was found superior to early (62.5%) imaging. The overall sensitivity and specificity of early Tc-99m MDP SMG were 71.4% and 62.5%, respectively. Although late Tc-99m MDP imaging showed 100% specificity, its sensitivity was only 23.8%. In the patients with palpable masses, both early Tc-99m MDP and Tc-99m MIBI showed equal sensitivity (100%), but the sensitivity of early Tc-99m MIBI (37.5%) was found slightly higher than Tc-99m MDP (25.0%) for nonpalpable breast lesions. The sensitivity of Tc-99m MIBI and Tc-99m MDP SMG in detecting metastatic axillary involvement was 66.6% and 50%, respectively. High sensitivity and specificity together with its low cost, easy availability and the possibility of detecting bone metastases seems to make Tc-99m MDP a contributive agent in the evaluation of breast lesions as an alternative to Tc-99m MIBI.     

Concordant uptake of Tc-99m sestamibi and Tl-201 in unsuspected breast tumor.

An unsuspected breast tumor was discovered in a 65-year-old woman referred for evaluation of possible ischemic heart disease. Marked tumor uptake of Tl-201 and concordant but less intense uptake of Tc-99m sestamibi (Tc-99m MIBI) was observed after both planar and SPECT imaging post treadmill exercise. Although many reports in the literature document Tl-201 tumor uptake, this is much less frequently reported with Tc-99m MIBI at this time. To the authors' knowledge, Tc-99m MIBI breast tumor uptake has not been reported to date. Tc-99m MIBI might prove useful in the detection of primary and metastatic breast carcinoma, and warrants further investigation.     

Tc-99m(V)-DMSA in wound infection after closure of an ileostomy

We present a 71-year-old man who underwent closure of an ileostomy and had a fever seven days post surgery. Both Tc-99m(V)-dimercaptosuccinic acid (DMSA) and gallium-67 citrate scans showed increased tracer accumulation in the right lower quadrant of the abdomen. Tc-99m(V)-DMSA scintigraphy can be a rapid alternative tool in the detection of wound infection in patients after ileostomy closure.     

Comparison of In-111 octreotide and Tc-99m (V) DMSA scintigraphy in the detection of medullary thyroid tumor foci in patients with elevated levels of tumor markers after surgery.

PURPOSE: In this retrospective study, the authors evaluated the utility of In-111 octreotide (OctreoScan) and Tc-99m (V) DMSA scintigraphy for the localization of recurrent metastatic tumor foci in patients with medullary thyroid cancer (MTC) and compared the findings with those of conventional radiologic imaging methods. METHODS: The scintigraphic images were compared with computed tomography (CT) and magnetic resonance imaging (MRI) and ultrasonography (US) in 14 patients (8 men, 6 women; age range, 22 to 74 years) with elevated calcitonin and carcinoembryonic antigen levels after total thyroidectomy. All scintigraphic image findings were evaluated qualitatively as mild uptake (+) and moderate to marked uptake (++). RESULTS: In-111 octreotide may be superior to Tc-99m (V) DMSA for the detection of tumor foci of patients with MTC on a patient basis (78.5% versus 57.1%) and on a lesion basis (44.1% versus 30.2%). The sensitivity rate for In-111 octreotide (78.5%) was also similar to that of CT and MRI on a patient basis. Conversely, the combined use of Tc-99m (V) DMSA and In-111 octreotide revealed the best sensitivity rate (85.7%) on a patient basis, whereas the combined use of CT and MRI showed the best sensitivity rate (81.3%) on a lesion basis. CONCLUSIONS: These findings suggest that In-111 octreotide is superior to Tc-99m (V) DMSA and has a similar sensitivity rate to CT and MRI for the diagnosis of recurrent or metastatic MTC. Although the combined use of In-111 octreotide and Tc-99m (V) DMSA was most sensitive, the combined use of CT and MRI with radionuclide imaging methods may better detect more metastatic tumor foci.     

Clinical experience with Tc-99m MIBI imaging in patients with malignant tumors. Preliminary results and comparison with Tl-201.

Tc-99m MIBI imaging was performed in 34 patients with histopathologically proven malignant tumors. The study was performed in two steps. In the first step, only Tc-99m MIBI imaging was performed (Group 1). In the second step, both Tc-99m MIBI and Tl-201 imaging were performed for comparison (Group 2). Seventeen patients were studied in each step. The size of the smallest primary tumor (breast cancer) was 15 x 10 mm, and that of the largest (lung cancer) was 145 x 130 mm. Of the 34 patients, 26 showed Tc-99m MIBI uptake at the tumor site. In Group 1, 12 patients showed Tc-99m MIBI tumor uptake, but no uptake was detected in five patients (squamous cell carcinoma of the esophagus, teratoma of the testis, nonHodgkin's lymphoma, and squamous cell carcinoma of the lung). In Group 2, 13 patients showed both Tc-99m MIBI and Tl-201 uptake at the tumor site, but one patient with breast cancer showed only Tc-99m MIBI uptake, and three patients showed no Tc-99m MIBI and Tl-201 uptake (embryonal cell carcinoma of the testis, hepatocellular carcinoma). The overall sensitivity of Tc-99m MIBI imaging was 76.4%. In Group 2, the sensitivity was 82.3% for Tc-99m MIBI and 76.4% for Tl-201. Our preliminary clinical experience suggests that Tc-99m MIBI can be helpful in localizing malignant tumors and that its sensitivity is slightly higher than Tl-201.     

The value of Tc-99m (V) dimercaptosuccinic acid in detecting intra-abdominal infection: compared with gallium scan

Objective Gallium-67 (Ga-67) and labeled leukocytes are useful in the detection of an unknown infectious source. However, the delay in the diagnosis of a Ga-67 citrate scan (gallium scan) and the complicated labeling technique of a leukocyte scan are major drawbacks to their clinical use. Recently, Tc-99m (V) dimercaptosuccinic acid (DMSA) has been found to be very useful in the detection of infection. Tc-99m (V) DMSA is inexpensive, easy to prepare, and provides a result within hours. In this study, we evaluated the potential of Tc-99m (V) DMSA scan (DMSA scan) in the detection of intra-abdominal infection. Methods A total of 33 patients who suffered from an unknown cause of fever after colorectal surgery were enrolled in this study. All patients received both a gallium scan and a DMSA scan. DMSA scintigraphy was performed 3–4 h after an injection of 740 MBq (20 mCi) of Tc-99m DMSA. After completion of the DMSA image, 111 MBq (3 mCi) of Ga-67 citrate was injected intravenously. Gallium scintigraphy was performed after 24 h and later as needed. Results Of the 33 patients, 17 (51.5%) were diagnosed with intra-abdominal abscesses. For DMSA scans, the sensitivity, specificity, and overall accuracy were 88.2%, 93.7%, and 90.9%, respectively. For gallium scans, the diagnostic sensitivity, specificity, and accuracy were 100%, 87.5%, and 93.9%, respectively. No statistical difference was found in the diagnostic accuracy between these two diagnostic modalities using Fisher's exact test. Conclusions DMSA scan is a useful alternative to gallium scan in the detection of intra-abdominal infection in patients with colorectal surgery because Tc-99m DMSA is inexpensive, easy to prepare, and most importantly the result can be obtained within hours.     

Tc-99m MIBI SPECT is useful for noninvasively predicting the presence of MDR1 gene-encoded P-glycoprotein in patients with hepatocellular carcinoma.

PURPOSE: Resistance to chemotherapeutic drugs continues to be one of the major unsolved problems in the treatment of cancer. Multidrug resistance is defined as the ability of cells exposed to a single drug to develop resistance to a broad range of structurally and functionally unrelated drugs as a result of enhanced outward transport of drugs mediated by P-glycoprotein that is encoded by multidrug resistance genes. Recent evidence has shown that Tc-99m MIBI is a suitable transport substrate for P-glycoprotein. A potential advantage of Tc-99m MIBI SPECT is its superiority to diagnose noninvasively the presence of P-glycoprotein overexpression in vivo. In this study, the authors determined the association of enhanced MIBI efflux in Tc-99m MIBI SPECT with overexpression of P-glycoprotein in hepatocellular carcinoma. MATERIALS AND METHODS: Thirty-five patients with hepatocellular carcinoma were enrolled in the study. Tc-99m MIBI SPECT was performed 10 minutes after intravenous injection of 20 mCi Tc-99m MIBI. All patients had liver biopsy or surgery within 1 week of MIBI imaging. Immunohistochemical study of the biopsy or resected hepatocellular carcinoma specimens was performed using the avidin-biotin-peroxidase technique with monoclonal antibody JSB-1 directed against P-glycoprotein. RESULTS: On Tc-99m MIBI SPECT, 30 of 35 (85.7%) patients with hepatocellular carcinoma had no Tc-99m MIBI uptake in tumor lesions, whereas five patients with hepatocellular carcinoma had Tc-99m MIBI uptake in tumor lesions. P-glycoprotein expression was observed in tumor tissues of all the patients without Tc-99m MIBI uptake, whereas among the five patients with Tc-99m MIBI uptake, no P-glycoprotein expression was seen in tumor lesions (P < 0.015). CONCLUSION: Tc-99m MIBI SPECT is useful for noninvasively predicting the presence of MDR1 gene-encoded P-glycoprotein in patients with hepatocellular carcinoma.     

Tc-99m DMSA renal uptake: influence of biochemical and physiologic factors

Thirty-eight female Sprague-Dawley rats were studied to determine the effects of (a) tubular blockade and (b) commonly encountered changes in hydration and acid-base balance, on the urinary excretion and renal localization of Tc-99m dimercaptosuccinic acid (DMSA). Ten additional rats were studied to quantitate the in vivo protein binding of Tc-99m DMSA, and a final group of 12 animals was used to quantitate DMSA distribution in animals with diminished functional renal mass. Both osmotic diuresis and dehydration by water deprivation for 24 hr resulted in a plasma clearance of DMSA slower than in control animals. Acid-base imbalances significantly affected the renal accumulation of DMSA, and acidosis was associated with markedly increased background due to increased liver accumulation. The protein-bound portion of Tc-99m DMSA in the plasma was high, reaching 89% within the first 5 min, and rising very slightly (n.s.) ith time. The unbound portion of DMSA had a plasma clearance slightly higher than the GFR. Ablation of large amounts of renal tissue, resulting in significant decreases in GFR. Ablation of large amounts of renal tissue, resulting in significant decreases in GFR, did not significantly affect the renal localization of DMSA in the intact portions of the kidneys. These data demonstrate that commonly encountered changes in acid-base balance and hydration will significantly alter the biologic distribution of Tc-99m DMSA. These factors should be controlled when carrying out clinical studies.     

False-negative Tc-99m MIBI scintigraphy in histopathologically proved recurrent high-grade oligodendroglioma

Tc-99m MIBI is a small lipophilic radioligand that enters cells by diffusion and is preferentially trapped in mitochondria. As a result of the high mitochondrial activity in tumors, Tc-99m MIBI accumulates significantly more in tumor tissue compared with normal tissues. Accordingly, Tc-99m MIBI has been used successfully to visualize primary, metastatic, and recurrent tumor. In brain tumors, Tc-99m MIBI SPECT has been shown to identify tumor recurrence after treatment in high-grade gliomas. In this report, early (30 minutes after injection) and delayed (4 hours after injection) Tc-99m MIBI SPECT did not visualize a histopathologically proved recurrent high-grade oligodendroglioma. Increased vascular supply, disruption of the blood-brain barrier, high-grade cancer, and viability of tumor cells are decisive factors related to increased Tc-99m MIBI uptake in brain tumors. However, the authors' results suggest that still other mechanisms may be involved in Tc-99m MIBI accumulation, which may account for false-negative imaging in brain tumors.     

Identification of sentinel lymph node in stage I-II breast cancer with lymphoscintigraphy and surgical gamma probe: comparison of Tc-99m MIBI and Tc-99m sulfur colloid

AIM: To evaluate the efficacy of the surgical gamma probe (SGP) after peritumoral injection of Tc-99m MIBI and filtered Tc-99m sulfur colloid (SC) in sentinel lymph node (SLN) detection in stage I and II breast cancer for deciding on the need for axillary dissection. MATERIALS AND METHODS: Thirty patients with stage I-II breast cancer had peritumoral injection of Tc-99m MIBI (74 MBq/0.2 mL [2 mCi/0.2 mL] at 4 different locations) and 42 different patients had peritumoral injection of filtered Tc-99m sulfur colloid (50 MBq/0.2 mL [1.3 mCi/0.2 mL] at 4 different locations). Anterior, lateral, and anterolateral spot images were acquired at 10, 30, 45, 60, and 120 minutes and 24 hours are injection in 5 patients. During surgery, counts were obtained from the injection site, affected breast tissue, internal mammary, axillary, and supraclavicular regions and the contralateral side using the gamma probe. Peritumoral blue dye was also injected during surgery. The first lymph nodes with counts at least twice the background tissue and/or with blue dye uptake were surgically isolated. Modified radical mastectomy and axillary dissection were performed. RESULTS: Histopathologic evaluation was made on SLN and other excised tissues. In the Tc-99m sulfur colloid group, lymphatic drainage and lymph nodes were demonstrated with lymphoscintigraphy in 31 of 42 patients. SLN was detected by SGP in 35 of 42 patients. In the Tc-99m MIBI group, lymphatic drainage and lymph nodes were visualized with lymphoscintigraphy in 23 of 30 patients. SLN was detected in 25 of 30 patients with SGP in this group. CONCLUSION: In patients with stage I-II breast cancer, SLN could be successfully demonstrated with lymphoscintigraphy and SGP by the peritumoral injection of filtered Tc-99m sulfur colloid and Tc-99m MIBI.