Technetium-99m-sestamibi scintimammography of benign and malignant phyllodes tumors

We presented two cases of phyllodes tumor of the breast examined by^99mTc-sestamibi (MIBI) two-phase scintimammography. In the case with malignant phyllodes tumor,^99mTc-MIBI accumulation was recognized on both early and delayed images. In the case with benign phyllodes tumor, however,^99mTc-MIBI accumulation was recognized on only the early image.^99mTc-MIBI delayed imaging may have the potential to distinguish between benign and malignant phyllodes tumors.     

Evaluation of cold areas on the thyroid scan with 99mTc Solcocitran

Cold areas on a ^99mTc pertechnetate thyroid scan were reevaluated using ^99mTc Solcocitran in 31 patients. In 27 patients surgical specimens were obtained for histologic studies. Of 20 benign lesions, five showed a relatively increased uptake of ^99mTc Solcocitran. Two of seven malignant lesions were interpreted as positive on the ^99mTc Solcocitran scan. This study indicates that ^99mTc Solcocitran is not a valuable radiopharmaceutical for differentiating cold areas.     

Is [99mTc]glucarate uptake mediated by fructose transporter GLUT-5?

PurposeThere is growing interest in the ability of [^99mTc]Glucarate ([^99mTc]GLA) to accumulate in viable tumor cells. Recent vivo studies suggest that [^99mTc]Glucarate could be helpful for tumor detection. Fructose transport is thought to be implicated. It is clearly established that facilitated fructose transport in tumor cells is related to the GLUT-5 transporter. This study therefore investigated whether [^99mTc]GLA uptake is mediated by GLUT-5 transporter.MethodsDifferent tumor cell lines were used. Modulation of GLUT-5 expression was assessed with and without antisense oligonucleotides directed against GLUT-5. GLUT-5 expression was assessed by indirect cell ELISA. To correlate GLUT-5 expression with tracer accumulation, [^99mTc]GLA uptake was determined after antisense treatment. A competition with fructose was also monitored.ResultsInhibition of GLUT-5 expression by antisense oligonucleotides directed against GLUT-5 was effective after 24 h. An optimal of 10 μM antisense oligonucleotides directed against GLUT-5 produced a 30%–40% decrease in protein expression. Modulation of [^99mTc]GLA uptake was monitored either by use of specific antisense oligonucleotides or by competition with fructose. Both of them produced a significant decrease of [^99mTc]GLA accumulation in all tested cell lines.ConclusionOur results clearly demonstrate that [^99mTc]GLA uptake is related to GLUT-5 transporter expression and transport. In tumor imaging, [^99mTc]GLA may be a useful tool for non-invasive detection of malignant tumors expressing high levels of GLUT-5 transporter as, for example, breast cancers.     

Retrospective review: usefulness of a number of imaging modalities including CT, MRI, technetium-99m pertechnetate scintigraphy, gallium-67 scintigraphy and F-18-FDG PET in the differentiation of benign from malignant parotid masses

Objective The aim of this study is to evaluate an imaging approach using computed tomography (CT), magnetic resonance imaging (MRI), technetium-99m pertechnetate scintigraphy (^99mTc pertechnetate scintigraphy), gallium-67 scintigraphy (⁶⁷Ga scintigraphy) and fluorine-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET). Material and Methods We reviewed retrospectively 59 patients with parotid masses. CT, MRI,⁶⁷Ga scintigraphy,^99mTc pertechnetate scintigraphy, and¹⁸F-FDG PET were performed. Results All of the benign tumors had smooth margins on CT and MRI. Patients with inflammatory lesions and malignant lesions showed well-defined margins or ill-defined margins. All Warthin's tumors showed high technetium accumulation. Many of malignant tumors showed high FDG accumulation. Both pleomorphic adenomas and Warthin's tumors showed high accumulation in some cases on¹⁸F-FDG PET. Among 15 patients with pleomorphic adenoma, 14 patients showed marked hyperintensity relative to CSF on T2-weighted images and partial enhancement on contrast-enhanced T1-weighted images. Combination of several imaging modarity offered usefulness of differential diagnosis for parotid masses. Conclusion An efficient combination of imaging methods may be helpul for achieve the correct diagnosis.     

99 Tcm-MIBI乳腺显像诊断乳腺癌评判方法的探讨

目的：探讨^99Tc^m-甲氧基异丁基异腈（MIBI）显像诊断乳腺癌的评判方法。方法：对100例乳腺肿瘤患者行^99Tc^m-MIBI平面显像,分别计算肿瘤与健侧对应部位（T／N）、肿瘤与胸骨（T／S）、肿瘤与心脏（T／H）的放射性比值,比较三者诊断乳腺癌的价值,确定最佳临界点,观察不同时相显像诊断乳腺癌的差异。结果：T／N检测乳腺癌的灵敏度、特异性和准确性最好,分别为84％、90％和87％;T／H分别为70％（P＞0．05）、72％（P＜0．05）、71％（P＜0．01）;T／S分别为58％（P＜0．01）、78％（P＞0．05）和68％（P＜0．01）。T／N比值在1．1－1．2间诊断乳腺癌的准确性最高。10或30min显像诊断乳腺癌结果无差异。结论：^99Tc^m-MIBI乳腺显像诊断乳腺癌较合适的评判方法为：选择T／N为判断指标,比值取1．1－1．2,显像时间为10或30min均可。     

The use of technetium-99m methoxyisobutylisonitrile breast scintigraphy to evaluate palpable breast masses

Thirty-eight female patients (age range: 31–79 years) with breast masses underwent technetium-99m methoxyisobutylisonitrile (^99mTc-MIBI) breast scintigraphy in order to assess the value of this technique in the detection of breast carcinomas and in their differentiation from benign breast masses. The results showed that 27 of the 32 cases of breast carcinoma were detected by ^99mTc-MIBI breast scintigraphy. In contrast, none of the six benign lesions could be detected by this method. The diagnostic sensitivity, specificity and accuracy were 84%, 100% and 87%, respectively, in the differentiation of malignant and benign breast masses. In conclusion, we consider ^99mTc-MIBI breast scintigraphy is useful in distinguishing malignancies from benign breast masses. Correspondence to: C.H. Kao     

Imaging of HER3-expressing xenografts in mice using a 99mTc(CO)3-HEHEHE-ZHER3:08699 affibody molecule

Purpose

Human epidermal growth factor receptor type 3 (HER3) is a transmembrane receptor tyrosine kinase belonging to the HER (ErbB) receptor family. Membranous expression of HER3 is associated with trastuzumab resistance in breast cancer and the transition to androgen independence in prostate cancer. Imaging of HER3 expression in malignant tumors may provide important diagnostic information that can influence patient management. Affibody molecules with low picomolar affinity to HER3 were recently selected. The aim of this study was to investigate the feasibility of HER3 imaging using radiolabeled Affibody molecules.

Methods

A HER3-binding Affibody molecule, Z₀₈₆₉₉, with a HEHEHE-tag on N-terminus was labeled with ^99mTc(CO)₃ using an IsoLink kit. In vitro and in vivo binding specificity and the cellular processing of the labeled binder were evaluated. Biodistribution of ^99mTc(CO)₃-HEHEHE-Z₀₈₆₉₉ was studied over time in mice bearing HER3-expressing xenografts.

Results

HEHEHE-Z₀₈₆₉₉ was labeled with ^99mTc(CO)₃ with an isolated yield of >80 % and a purity of >99 %. Binding of ^99mTc(CO)₃-HEHEHE-Z₀₈₆₉₉ was specific to BT474 and MCF7 (breast cancer), and LS174T (colon cancer) cells. Cellular processing showed rapid binding and relatively quick internalization of the receptor/Affibody molecule complex (70 % of cell-associated radioactivity was internalized after 24 h). The tumor targeting was receptor mediated and the excretion was predominantly renal. Receptor-mediated uptake was also found in the liver, lung, stomach, intestine, and salivary glands. At 4 h pi, tumor-to-blood ratios were 7?±?3 for BT474, and 6?±?2 for LS174T xenografts. LS174T tumors were visualized by microSPECT 4 h pi.

Conclusions

The results of this study suggest the feasibility of HER3-imaging in malignant tumors using Affibody molecules.     

Diagnostic angioscintigraphic evaluation of malignant hepatic tumors before catheter embolization: Determination of shunt,flow distribution,and reflux

Purpose: The aim of this study was to evaluate quantitatively arteriovenous shunts in malignant liver tumors by injection of ^99mTc macroaggregates of albumin (MAA) into the tumor-feeding artery after selective catheterization. Methods: In 40 patients with malignant liver tumors (33 hepatocellular carcinomas and 7 metastases of colorectal cancer), a mean dose of 200 MBq ^99mTc MAA was injected arterially during angiography. The embolized area and the lungs were then visualized using a gamma camera. A dedicated computer program calculated pulmonary shunt rates. Results: The majority of patients (n= 30) with hepatocellular carcinoma showed small shunts varying from 0 to 15%; only 3 of these patients had shunts ranging from 18% to 37%. In patients with colorectal carcinoma metastases (n= 7) the shunt varied from 0 to 3% (2 ± 1%), probably due to a physiological shunt in normal liver tissue in the embolized area. Importantly, the degree of shunt found bore no correlation to the tumor volume or to the pattern of vascularity on angiography. Conclusion: Diagnostic angioscintigraphy is a useful tool for pretherapeutic evaluation of the capacity of an individual tumor to retain particles and to measure extratumoral shunting; these are essential for therapy planning, as they can help to increase the safety and effectiveness of embolization.     

Efficacy of <Superscript>99m</Superscript>Tc pertechnetate and <Superscript>131</Superscript>I radioisotope therapy in sodium/iodide symporter (NIS)-expressing neuroendocrine tumors in vivo

Purpose There is growing interest in the human sodium/iodide symporter (NIS) gene both as a molecular imaging reporter gene and as a therapeutic gene. Here, we show the feasibility of radioisotope therapy of neuroendocrine tumors. As a separate application of NIS gene transfer, we image NIS-expressing tumors with pinhole SPECT in living subjects. Methods Biodistribution studies and in vivo therapy experiments were performed in nude mice carrying stably NIS-expressing neuroendocrine tumor xenografts following i.v. injection of ¹³¹I and ^99mTc pertechnetate. To show the usefulness of NIS as an imaging reporter gene, ^99mTc pertechnetate uptake was imaged in vivo using a clinical gamma camera in combination with a custom-made single pinhole collimator, followed by SPECT/small animal MRI data coregistration. Results NIS-expressing neuroendocrine tumors strongly accumulated ¹³¹I and ^99mTc pertechnetate, as did thyroid, stomach, and salivary gland. The volume of NIS-expressing neuroendocrine tumors decreased significantly after therapeutic administration of ¹³¹I or ^99mTc pertechnetate, whereas control tumors continued to grow. NIS-mediated uptake of ^99mTc pertechnetate could be imaged in vivo at high resolution with a clinical gamma camera equipped with a custom-made single pinhole collimator. High-resolution functional and morphologic information could be combined in a single three-dimensional data set by coregistration of SPECT and small animal MRI data. Lastly, we demonstrated a therapeutic effect of ^99mTc pertechnetate on NIS-expressing neuroendocrine tumors in cell culture and, for the first time, in vivo, thought to be due to emitted Auger and conversion electrons. Conclusions NIS-expressing neuroendocrine tumors efficiently concentrate radioisotopes, allowing for in vivo high-resolution small animal SPECT imaging as well as rendering possible successful radioisotope therapy of neuroendocrine tumors.     

Imaging of intraperitoneal tumors with technetium-99m GSA

^99mTc labeled galactosyl serum albumin (GSA) has been used clinically as a receptor-binding agent for the assessment of liver function. The aim of this study was to investigate the usefulness of^99mTc-GS A in intraperitoneal (i.p.) tumor imaging. A tumor model was established by i.p. inoculating nude mice with human ovarian cancer cell SHIN-3, or colon cancer cell LS180. Radiolabels were i.p. injected into the tumor-bearing mice and the biodistribution of radioactivity was examined. After administration,^99mTc-GSA rapidly accumulated in the tumor. The tumor uptake was 5.82-8.46 %ID/g from 30 min to 6 h after the injection. Radioactivity in the blood was very low, less than 0.3 %ID/g, resulting in high tumor-to-blood ratio. Tumors could be clearly seen by scintigraphic imaging. Accumulation of i.p.-injected^99mTc labeled human serum albumin (HSA) in i.p. tumors was similar to that of^99mTc-GSA, but radioactivity of^99mTc-HSA in the circulation was high, resulting in a significantly lower tumor-to-blood ratio. In conclusion,^99mTc-GSA, when i.p. injected, accumulated in i.p. tumors and cleared from circulation rapidly, which would make it useful for the imaging of i.p. tumors.     

Initial experience with Tc-99m-HM-PAO in the study of brain tumors

A preliminary study of the distribution of the ^99mTc complex of hexamethylpropylene amine oxime (HM-PAO) in 12 patients with brain neoplasms before, during, and after radiotherapy has been performed. Untreated brain tumors were found to exhibit a range of ^99mTc-HM-PAO uptake, varying from areas of markedly increased isotope activity to photopenic areas, when compared to normal brain tissue. A ratio of ^99mTc-HM-PAO tumor uptake to contralateral normal tissue uptake was calculated prior to and during radiotherapy. This ratio tended to return towards unity in lesions responding to therapy. A predictable alteration in whole brain ^99mTc-HM-PAO uptake during radiotherapy was not demonstrated. Unlike the radiolabeled amines, ^99mTc-HM-PAO localizes in primary tumors, probably indicating that its uptake mechanism is independent of non specific amine receptors. ^99mTc-HM-PAO may be useful in the study of brain tumor physiology and response to therapy.     

First experiences with technetium-99m furifosmin as tumour-seeking agent in breast cancer and recurrent ovarian cancer

Recent in vitro studies suggest that technetium-99m furifosmin may have tumour-seeking properties. We analysed the diagnostic value of^99mTc-furifosmin scintigraphy in nine patients with documented carcinoma of the breast and in eight patients with continued recurrent ovarian cancer. In the breast,^99mTc-furifosmin failed to visualize the primary malignant tumour and the associated malignant lymph nodes in all patients. In contrast, multiple sites of increased tracer uptake were demonstrated in one patient with acute benign inflammatory breast disease. In four of eight patients with recurrent ovarian cancer,^99mTc-furifosmin scintigraphy demonstrated early (5 min p.i.) localized increased uptake corresponding to adhesions to the bowel as diagnosed by computed tomography, but failed to reveal further abnormalities in all patients. The present study demonstrates that furifosmin is of no value in the imaging of breast cancer and recurrent ovarian cancer. These results do not continue the pattern observed in cell culture studies and are quite in contrast to the findings of mammoscintigraphy using^99mTc-methoxyisobutylisonitrile and^99mTc-tetrofosmin.     

Preparation and evaluation of bombesin peptide derivatives as potential tumor imaging agents: effects of structure and composition of amino acid sequence on in vitro and in vivo characteristics

ObjectivesAmong the many clinically relevant peptide receptor systems, bombesin (BN) receptors have attracted enormous attraction due to their overexpression in various frequently occurring human tumors including breast and prostate, thus making such receptors promising targets with radiolabeled BN analogs. The present study describes the preparation and evaluation of a series of new BN derivatives as potential tumor imaging agents.MethodsSeveral new BN derivatives with the common structure MAG₃-X-BN(1–14 or 6–14), where X=Asp or Asp-Asp, were synthesized by solid-phase peptide synthesis. S-benzoylmercaptoacetic acid was incorporated at the end of synthesis via manual conjugation to yield MAG₃-BN conjugates. Radiolabeling with ^99mTc was accomplished by ligand exchange method. The receptor-binding affinity assays were performed in MDA-MB-231, MCF-7, T47-D and PC-3 cancer cell lines. In vivo biodistribution and clearance kinetics were assessed in Balb/c mice, and tumor targeting efficacy was determined in nude mice bearing breast tumor xenografts.ResultsThe peptides were prepared conveniently and radiolabeled efficiently with ^99mTc (up to 95% labeling efficiency). In vitro cell binding assays demonstrated high affinity (values in the nanomolar range) of ^99mTc peptides towards breast and prostate cancer cell lines. In addition, the radioconjugates displayed significant internalization (values ranged between 19% and 35%) in tumor cells. In vivo biodistribution and biokinetics are characterized by efficient clearance from the blood and variable degrees of excretion through the renal pathway. In vivo tumor targeting studies displayed variable uptake capacity of different BN derivatives, underlining the influence of specific amino acid sequence on tumor targeting profiles. Tumor uptake was always higher than the radioactivity in the blood and muscle, with good tumor retention and good tumor-to-blood and tumor-to-muscle ratios, indicating the potential of these agents for targeting tumors in vivo.ConclusionsThe combination of favorable in vitro and in vivo properties may render these BN peptides as potential candidates for targeting BN/GRP receptor-positive tumors. They deserve further evaluation to determine their real strength. The present data indeed provide useful information regarding peptide structure–pharmacologic activity relationship, which might be useful in designing and developing new BN-like peptides for efficient targeting of tumors in vivo.     

Bleomycin labelled with 99mTc for differentiation of breast tumors

Bleomycin labelled with 99mTc was used to differentiate benign and malignant breast tumors. Breast scintigraphy was performed 15 and 60 min following the IV injection of 5 mCi99mTc bleomycin. Thirty-two patients with breast tumor (14 carcinomas and 18 benign nodular lesions) were examined. Cytologic or histologic verification of the tumor was carried out in all cases. All malignant tumors of the breast in the investigated group of patients revealed significantly increased accumulation of 99mTc-bleomycin.     

Is a Technetium-99m Macroaggregated Albumin Scan Essential in the Workup for Selective Internal Radiation Therapy with Yttrium-90? An Analysis of 532 Patients

Purpose

To determine if baseline patient, tumor, and pretreatment evaluation characteristics could help identify patients who require technetium-99m (^99mTc) macroaggregated albumin (^99mTc MAA) imaging before selective internal radiation therapy (SIRT).

Synthesis and biodistribution of 99mTc chelates of acridinyl iminodiacetic acids

In an attempt to obtain compounds for scintigraphic tumor localization, the ability of certain acridine compounds to localize in tumors was exploited. Derivatives of the acridine nucleus were made with an iminodiacetic acid group attached which has been shown to be a suitable chelating group for ^99mTc.The compounds labelled with ^99mTc were screened for tumor-localizing ability by injection into rats bearing transplanted lymphatic leukaemias.The biodistribution of these compounds showed a lack of specific concentration in the tumor model and a pattern of urinary and hepatobiliary excretion. It can be concluded that these compounds are unsuitable for scintigraphic tumor localization, at least for those based on this tumor model.     

Synthesis and Evaluation of 99mTc-Labeled Folate-Tripeptide Conjugate as a Folate Receptor-Targeted Imaging Agent in a Tumor-Bearing Mouse Model

Purpose

The folate receptor (FR) is an attractive molecular target since it is overexpressed in a variety of human tumors. The purpose of the present study was to synthesize and evaluate the feasibility of a novel ^99mTc-ECG-EDA (Glu-Cys-Gly-ethylenediamine)-folate as an FR-positive tumor imaging agent in a mouse tumor model.

Materials and Methods

ECG-EDA-folate was synthesized using solid phase peptide synthesis (SPPS) and radiolabeled with ^99mTc using tripeptide ECG as a chelator. FR-positive KB cells were inoculated in athymic nude mice. Following injection of ^99mTc-ECG-EDA-folate, serial scintigraphy and micro-SPECT/CT imaging were performed at various time points with and without pre-administration of excess free folate. Mean count densities (MCD) for regions of interest drawn on KB tumors and major normal organs at each time point were measured, and uptake ratios of tumor to normal organs were calculated.

Results

ECG-EDA-folate was labeled with ^99mTc with high radiolabeling efficiency and stability (>96 %). FR-positive tumors were clearly visualized on both scintigraphy and micro-SPECT/CT images and the tumor uptake of ^99mTc-ECG-EDA-folate was markedly suppressed with faint visualization of tumors by pre-administration of excess free folate on serial planar scintigraphy, indicating FR-specific binding of the agent. Furthermore, semiquantitative analysis of MCD data showed again that both tumor MCD and tumor-to-normal organ ratios decreased considerably by pre-administration of excess free folate, supporting FR-specific tumor uptake. Tumor-to-normal organ ratios approximately increased with time after injection until 4 h.

Conclusion

The present study demonstrated that ^99mTc-ECG-EDA-folate can bind specifically to FR with clear visualization of FR-positive tumors in a mouse tumor model.     

Synthesis and biological evaluation of a 99mTc-labelled sulfonamide conjugate for in vivo visualization of carbonic anhydrase IX expression in tumor hypoxia

IntroductionCarbonic anhydrase (CA) IX is a transmembrane protein overexpressed in many frequently occurring tumors associated with tumor hypoxia. Sulfonamides and their bioisosteres are known to inhibit CA IX activity. In this study, 4-(2-aminoethyl)benzenesulfonamide was conjugated to a tridentate ligand, N-2-picolyl-N-acetic acid and labeled with a ^99mTc(I)-tricarbonyl moiety resulting in [^99mTc(CO)₃ (L)] (L=N-(pyridin-2-yl-methyl)-N[2-(4-sulfamoylphenyl)-ethyl]aminoethyl acetate) complex, [^99mTc]-5. Similarly the corresponding rhenium congener (Re-4) was synthesized. The in vitro CA IX affinity and inhibitory activity of Re-4 were determined and [^99mTc]-5 was evaluated as a tracer for in vivo visualisation of CA IX expression.MethodsEvaluation of the in vitro affinity (inhibition constant, K_i) of Re-4 for CA isozymes I, II, IX and XII was carried out by assaying the CA catalyzed CO₂ hydration activity and efficacy studies were performed in HT 29 cell lines expressing CA IX under normoxia or hypoxia. Biodistribution studies of [^99mTc]-5 were performed in xenograft mice bearing CA IX expressing tumors.ResultsThe in vitro affinity of Re-4 for CA IX was 58 nM and CA IX induced acidification of extracellular medium was efficiently reduced (P<.05) in the presence of 1 mM Re-4. Biodistribution studies indicated a maximal tumor uptake of [^99mTc]-5 of 0.1% ID/g at 30 min post injection.Conclusion[^99mTc]-5 and its rhenium congener were synthesized and characterized. In vitro studies showed that the rhenium compound has a high affinity for CA IX and effectively inhibits CA IX activity. In vivo studies revealed a limited tracer accumulation in a CA IX expressing tumor but with increasing tumor-to-blood activity ratios as a function of time.     

Evaluation of the relationship between [18F]FDG and P-glycoprotein expression: an experimental study

IntroductionP-glycoprotein (P-gp) is a cell-membrane-associated protein that transports a variety of drug substrates. We sought to evaluate the relationship between 2-[¹⁸F]fluoro-2-deoxy-d-glucose ([¹⁸F]FDG) and P-gp expression using breast carcinoma Bcap37/multidrug resistant (MDR1) and Bcap37 in vitro and in vivo.MethodsThe function of P-gp expressed in Bcap37/MDR1 cells was evaluated using verapamil (VER), a classical inhibitor of P-gp. The accumulation of ^99mTc-methoxyisobutylisonitrile ([^99mTc]MIBI) in vitro was measured. In vivo imaging of severe combined immune deficiency (SCID) mice implanted with Bcap37 and Bcap37/MDR1 cells was performed by scintigraphy and micro-positron emission tomography (PET).ResultsThe uptake of [^99mTc]MIBI was 0.62%±0.05% in the Bcap37/MDR1 cells and 2.02%±0.28% in the Bcap37 cells. VER significantly increased the uptake of [^99mTc]MIBI in the Bcap37/MDR1 cells (1.90%±0.09%) but not in the Bcap37 cells (2.15%±0.27%). In vivo, neither the Bcap37 nor Bcap37/MDR1 tumors grown in the SCID mice could be detected by [^99mTc]MIBI scintigraphy. Both the Bcap37 and Bcap37/MDR1 tumors were visible by micro-PET. The mean standardized uptake value (SUV) was significantly higher in the Bcap37 tumors (1.00±0.06) than in the Bcap37/MDR1 (0.67±0.11) tumors. VER significantly increased the mean SUV in the Bcap37/MDR1 tumors (1.02±0.16) but not in the Bcap37 tumors (1.09±0.22).Conclusions[¹⁸F]FDG combined with VER may be an effective noninvasive method of determining P-gp expression in tumors.     

Three patients with bilateral breast tumors examined by technetium-99m-sestamibi scintimammography

We presented three patients with bilateral breast tumors (one with breast cancers, one with breast cancer and fibroadenoma, and one with fibroadenomas) examined by^99mTc-hexakis 2-methoxy-isobutylisonitrile (MIBI) scintimammography. In all cases^99mTc-MIBI uptake was recognized only in the breast cancers.^99mTc-MIBI scintimammography was useful in evaluating bilateral breast tumors since preoperative diagnosis is valuable in determining correct surgical treatment.