[Tc-99m]-sestamibi uptake and washout in locally advanced breast cancer are correlated with tumor blood flow

Principles of Tracer Kinetic Analysis in Oncology, Part II: Examples and Future Directions

Learning Objectives: On successful completion of this activity, participants should be able to (1) describe examples of the application of PET tracer kinetic analysis to oncology; (2) list applications research and possible clinical applications in oncology where kinetic analysis is helpful; and (3) discuss future applications of kinetic modeling to cancer research and possible clinical cancer imaging practice.Financial Disclosure: This work was supported by KL2 TR001879, R01 CA211337, R01 CA113941, R33 CA225310, Komen SAC130060, R50 CA211270, and K01 DA040023. Dr. Pantel is a consultant or advisor for Progenics and Blue Earth Diagnostics and is a meeting participant or lecturer for Blue Earth Diagnostics. Dr. Mankoff is on the scientific advisory boards of GE Healthcare, Philips Healthcare, Reflexion, and ImaginAb and is the owner of Trevarx; his wife is the chief executive officer of Trevarx. The authors of this article have indicated no other relevant relationships that could be perceived as a real or apparent conflict of interest.CME Credit: SNMMI is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor continuing education for physicians. SNMMI designates each JNM continuing education article for a maximum of 2.0 AMA PRA Category 1 Credits. Physicians should claim only credit commensurate with the extent of their participation in the activity. For CE credit, SAM, and other credit types, participants can access this activity through the SNMMI website (http://www.snmmilearningcenter.org) through April 2025.Kinetic analysis of dynamic PET imaging enables the estimation of biologic processes relevant to disease. Through mathematic analysis of the interactions of a radiotracer with tissue, information can be gleaned from PET imaging beyond static uptake measures. Part I of this 2-part continuing education paper reviewed the underlying principles and methodology of kinetic modeling. In this second part, the benefits of kinetic modeling for oncologic imaging are illustrated through representative case examples that demonstrate the principles and benefits of kinetic analysis in oncology. Examples of the model types discussed in part I are reviewed here: a 1-tissue-compartment model (15O-water), an irreversible 2-tissue-compartment model (18F-FDG), and a reversible 2-tissue-compartment model (3'-deoxy-3'-18F-fluorothymidine). Kinetic approaches are contrasted with static uptake measures typically used in the clinic. Overall, this 2-part review provides the reader with background in kinetic analysis to understand related research and improve the interpretation of clinical nuclear medicine studies with a focus on oncologic imaging.

Molecular Breast Imaging in Clinical Practice

OBJECTIVE. The purpose of this article is to review clinical uses and image interpretation of molecular breast imaging (MBI) and clarify radiation risks. CONCLUSION. MBI detects additional cancers compared with conventional imaging in women with dense breasts and those with elevated risk of breast cancer. Its role as an imaging biomarker of cancer risk and in assessing neoadjuvant chemotherapy response is growing. Radiation risk is minimal; benefit-to-risk ratio is similar to that of mammography. MBI is low cost, well tolerated, and easily adapted into clinical practice.

Impact of short-term low-dose tamoxifen on molecular breast imaging background parenchymal uptake: a pilot study

BACKGROUND

High background parenchymal uptake (BPU) on molecular breast imaging (MBI) has been identified as a breast cancer risk factor. We explored the feasibility of offering a short-term intervention of low-dose oral tamoxifen to women with high BPU and examined whether this intervention would reduce BPU.

METHODS

Women with a history of high BPU and no breast cancer history were invited to the study. Participants had an MBI exam, followed by 30 days of low-dose oral tamoxifen at either 5 mg or 10 mg/day, and a post-tamoxifen MBI exam. BPU on pre- and post-tamoxifen MBI exams was quantitatively assessed as the ratio of average counts in breast fibroglandular tissue vs. average counts in subcutaneous fat. Pre-tamoxifen and post-tamoxifen BPU were compared with paired t tests.

RESULTS

Of 47 women invited, 22 enrolled and 21 completed the study (10 taking 5 mg tamoxifen, 11 taking 10 mg tamoxifen). Mean age was 47.7 years (range 41-56 years). After 30 days low-dose tamoxifen, 8 of 21 women (38%) showed a decline in BPU, defined as a decrease from the pre-tamoxifen MBI of at least 15%; 11 of 21 (52%) had no change in BPU (within ± 15%); 2 of 21 (10%) had an increase in BPU of greater than 15%. Overall, the average post-tamoxifen BPU was not significantly different from pre-tamoxifen BPU (1.34 post vs. 1.43 pre, p = 0.11). However, among women taking 10 mg tamoxifen, 5 of 11 (45%) showed a decline in BPU; average BPU was 1.19 post-tamoxifen vs. 1.34 pre-tamoxifen (p = 0.005). In women taking 5 mg tamoxifen, 2 of 10 (20%) showed a decline in BPU; average BPU was 1.51 post-tamoxifen vs.1.53 pre-tamoxifen (p = 0.99).

CONCLUSIONS

Short-term intervention with low-dose tamoxifen may reduce high BPU on MBI for some patients. Our preliminary findings suggest that 10 mg tamoxifen per day may be more effective than 5 mg for inducing declines in BPU within 30 days. Given the variability in BPU response to tamoxifen observed among study participants, future study is warranted to determine if BPU response could predict the effectiveness of tamoxifen for breast cancer risk reduction within an individual.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02979301 . Registered 01 December 2016.

Comparison of fan beam, slit-slat and multi-pinhole collimators for molecular breast tomosynthesis

Recently, we proposed and optimized dedicated multi-pinhole molecular breast tomosynthesis (MBT) that images a lightly compressed breast. As MBT may also be performed with other types of collimators, the aim of this paper is to optimize MBT with fan beam and slit-slat collimators and to compare its performance to that of multi-pinhole MBT to arrive at a truly optimized design. Using analytical expressions, we first optimized fan beam and slit-slat collimator parameters to reach maximum sensitivity at a series of given system resolutions. Additionally, we performed full system simulations of a breast phantom containing several tumours for the optimized designs. We found that at equal system resolution the maximum achievable sensitivity increases from pinhole to slit-slat to fan beam collimation with fan beam and slit-slat MBT having on average a 48% and 20% higher sensitivity than multi-pinhole MBT. Furthermore, by inspecting simulated images and applying a tumour-to-background contrast-to-noise (TB-CNR) analysis, we found that slit-slat collimators underperform with respect to the other collimator types. The fan beam collimators obtained a similar TB-CNR as the pinhole collimators, but the optimum was reached at different system resolutions. For fan beam collimators, a 6-8 mm system resolution was optimal in terms of TB-CNR, while with pinhole collimation highest TB-CNR was reached in the 7-10 mm range.

The clinical impact of molecular breast imaging in women with proven invasive breast cancer scheduled for breast-conserving surgery

Purpose

To investigate the clinical utility of molecular breast imaging (MBI) in patients with proven invasive breast cancer scheduled for breast-conserving surgery (BCS).

Methods

Following approval by the institutional review board and written informed consent, records of patients with newly diagnosed breast cancer scheduled for BCS who had undergone MBI for local staging in the period from March 2012 till December 2014 were retrospectively reviewed.

Results

A total of 287 women (aged 30–88 years) were evaluated. MBI showed T stage migration in 26 patients (9%), with frequent detection of in situ carcinoma around the tumor. Surgical management was adjusted in 14 of these patients (54%). In 17 of 287 patients (6%), MBI revealed 21 proven additional lesions in the ipsilateral, contralateral breast or both. In 18 of these additional foci (86%), detected in 15 patients, malignancy was found. Thirteen of these 15 patients had ipsilateral cancer and 2 patients bilateral malignancy. In total, MBI revealed a larger tumor extent, additional tumor foci or both in 40 patients (14%), leading to treatment adjustment in 25 patients (9%).

Conclusion

MBI seems to be a useful imaging modality with a high predictive value in revealing ipsilateral and bilateral disease not visualized by mammography and ultrasound. It may play an important role in delineating the extent of the index lesion during preoperative planning. Incorporation of MBI in the clinical work-up as an adjunct modality to mammography and ultrasound may lead to better selection of patients who could benefit from BCS.

First Clinical Experience Using Stereotactic Breast Biopsy Guided by 99mTc-Sestamibi

OBJECTIVE

The purpose of this study is to evaluate a new device using molecular breast imaging (MBI) for ^99mTc-sestamibi-guided stereotactic lesion localization as a complementary biopsy tool.

MATERIALS AND METHODS

From December 2012 to May 2016, a total of 38 consecutive women (mean age, 59 years; range, 41-77 years) underwent ^99mTc-sestamibi-guided biopsy using a new MBI-based device and were retrospectively reviewed. The biopsy modality used five steps: stereotactic localization of the ^99mTc-sestamibi-avid lesion, calculation of coordinates of the lesion location using dedicated software, placement of the needle, verification of the correct needle position, and tissue sampling with a vacuum-assisted device followed by placement of a radiologic marker at the biopsy site and ex vivo measurement of the biopsy specimens.

RESULTS

The procedure was technically successful in all 38 lesions. In all cases, biopsy samples were radioactive and adequate for histopathologic analysis. Nineteen lesions (50%) were found to be malignant, and the remaining lesions were found to be benign. The mean procedure time was 71 minutes (range, 44-112 minutes). The radiologic marker was successfully deployed in 37 lesions (97%). Two hematomas and three vasovagal reactions were observed.

CONCLUSION

Technetium-99m sestamibi-guided biopsy performed using a dedicated MBI-based device is technically feasible and represents a valuable complementary biopsy tool in breast lesion diagnosis.

Methodological aspects of 99mTc-sestamibi guided biopsy in breast cancer

Purpose

This review aims to discuss the methodological aspects of dedicated molecular breast imaging (MBI) using ^99mTc-sestamibi as radiotracer to guide biopsy of occult or unclear breast lesions on mammography (MG) and ultrasound (US) that are suspicious on MBI (BI-RADS criteria 4 and 5), including its advantages, limitations and future clinical applications.

Methods

Literature search was performed using the PubMed/MEDLINE database and “^99mTc-sestamibi”, “biopsy” and “breast cancer” as keywords. The search was restricted to English language.

Results

There are few studies on ^99mTc-sestamibi guided biopsy methods; to our knowledge, no full studies have yet been reported on clinical validation of this new biopsy procedure. This review describes technical aspects of ^99mTc-sestamibi guided biopsy and discusses the advantages and limitations of this procedure in comparison with MG, US and MRI-guided biopsy.

Conclusions

MBI-guided biopsy appears to be a complementary modality and is principally indicated in the case of occult or unclear breast lesions on MG/US, that are suspicious on MBI. The future indication is in targeted biopsies in patients with large heterogeneous tumours. Further studies are needed to define the accuracy of this biopsy procedure.

Changes in Glucose Metabolism and Blood Flow Following Chemotherapy for Breast Cancer

This article focuses on this application of positron emission tomography (PET) to breast cancer. The article first reviews the PET methodology used for breast cancer response assessment, with an emphasis on quantitative methods. This is followed by a review of results to date for neoadjuvant chemotherapy and therapy of metastatic breast cancer. Preliminary studies with tracers other than (18)F-fluordeoxyglucose are then reviewed. The article ends with a summary and a discussion of future directions.

Values of (99m)Tc-methoxyisobutylisonitrile imaging after first-time large-dose (131)I therapy in treating differentiated thyroid cancer

Objective

The aim of this study is to investigate the use of ^99mTc-methoxyisobutylisonitrile (MIBI) imaging for evaluating the treatment response of differentiated thyroid cancer (DTC) after the first administration of a high dose of ¹³¹I.

Methods

Patients with DTC who received ¹³¹I therapy underwent ^99mTc-MIBI imaging after successive increases in the therapeutic dose of ¹³¹I, and the serum levels of thyroglobulin (Tg) were measured.

Results

A total of 191 patients were enrolled in the final analysis, including 65 metastases and/or thyroid remnant-positive patients (22 patients with metastases and 43 patients with thyroid remnants). The sensitivity of ^99mTc-MIBI imaging for detecting positive cases and thyroid remnants was 56.9% and 39.5%, respectively, which was significantly lower than that of ¹³¹I imaging (92.3% and 100%, respectively, P<0.01 for both). The sensitivity of ^99mTc-MIBI imaging for detecting metastases was 90.9%, which was slightly higher than that of ¹³¹I imaging (77.3%, P>0.05). The Tg levels in the positive group were significantly higher than that in the negative group (P<0.01). In addition, the Tg levels in the ^99mTc-MIBI⁺/¹³¹I⁻ group were significantly higher than that in the ¹³¹I⁺/^99mTc-MIBI group (P<0.05).

Conclusion

After the first ¹³¹I therapy, although ^99mTc-MIBI imaging was able to detect the existence of metastatic lesions in patients with DTC better, its assessment for the removal efficiency of thyroid remnants was unsatisfactory. The results of ^99mTc-MIBI imaging showed good correlations with the Tg level.

Effect of menstrual cycle phase on background parenchymal uptake at molecular breast imaging

RATIONALE AND OBJECTIVES

The level of Tc-99m sestamibi uptake within normal fibroglandular tissue on molecular breast imaging (MBI), termed background parenchymal uptake (BPU), has been anecdotally observed to fluctuate with menstrual cycle. Our objective was to assess the impact of menstrual cycle phase on BPU appearance.

MATERIALS AND METHODS

Premenopausal volunteers who reported regular menstrual cycles and no exogenous hormone use were recruited to undergo serial MBI examinations during the follicular and luteal phase. A study radiologist, blinded to cycle phase, categorized BPU as photopenic, minimal mild, moderate, or marked. Change in BPU with cycle phase was determined, as well as correlations of BPU with mammographic density and hormone levels.

RESULTS

In 42 analyzable participants, high BPU (moderate or marked) was observed more often in luteal phase compared to follicular (P = .016). BPU did not change with phase in 30 of 42 participants (71%) and increased in the luteal phase compared to follicular in 12 (29%). High BPU was more frequent in dense breasts compared to nondense breasts at both the luteal (58% [15 of 26] vs. 13% [2 of 16], P = .004) and follicular phases (35% [9 of 26] vs. 6% [1 of 16], P = .061). Spearman correlation coefficients did not show any correlation of BPU with hormone levels measured at either cycle phase and suggested a weak correlation between change in BPU and changes in estrone and estradiol between phases.

CONCLUSIONS

We observed variable effects of menstrual cycle on BPU among our cohort of premenopausal women; however, when high BPU was observed, it was most frequently seen during the luteal phase compared to follicular phase and in women with dense breasts compared to nondense breasts.

Added value of semi-quantitative breast-specific gamma imaging in the work-up of suspicious breast lesions compared to mammography, ultrasound and 3-T MRI

OBJECTIVE

To prospectively analyse the diagnostic value of semi-quantitative breast-specific gamma imaging (BSGI) in the work-up of suspicious breast lesions compared with that of mammography (MG), breast ultrasound and MRI of the breast.

METHODS

Within a 15-month period, 67 patients with 92 breast lesions rated as Category IV or V according to the breast imaging reporting and data system detected with MG and/or ultrasound were included into the study. After the injection of 740-1110 MBq of Technetium-99m ((99m)Tc) SestaMIBI intravenously, scintigrams were obtained in two projections comparable to MG. The BSGI was analysed visually and semi-quantitatively by calculating a relative uptake factor (X). With the exception of two patients with cardiac pacemakers, all patients underwent 3-T breast MRI. Biopsy results were obtained as the reference standard in all patients. Sensitivity, specificity, positive- and negative-predictive values, accuracy and area under the curve were calculated for each modality.

RESULTS

Among the 92 lesions, 67 (72.8%) were malignant. 60 of the 67 cancers of any size were detected by BSGI with an overall sensitivity of 90%, only exceeded by ultrasound with a sensitivity of 99%. The sensitivity of BSGI for lesions <1 cm declined significantly to 60%. Overall specificity of ultrasound was only 20%. Specificity, accuracy and positive-predictive value were the highest for BSGI (56%, 80% and 85%, respectively). X was significantly higher for malignant lesions (mean, 4.27) and differed significantly between ductal types (mean, 4.53) and the other histopathological entities (mean, 3.12).

CONCLUSION

Semi-quantitative BSGI with calculation of the relative uptake factor (X) can help to characterize breast lesions. BSGI negativity may obviate the need for biopsy of breast lesions >1 cm with low or intermediate prevalence for malignancy.

ADVANCES IN KNOWLEDGE

Compared with morphological imaging modalities, specificity, positive-predictive value for malignancy and accuracy were the highest for BSGI in our study. BSGI negativity may support the decision not to biopsy in selected lesions with a low or low-to-moderate pre-test probability for malignancy.

Background parenchymal uptake during molecular breast imaging and associated clinical factors

OBJECTIVE. The purposes of this study were to describe the prevalence of background parenchymal uptake categories observed at screening molecular breast imaging (MBI) and to examine the association of background parenchymal uptake with mammographic density and other clinical factors. MATERIALS AND METHODS. Adjunct MBI screening was performed for women with dense breasts on previous mammograms. Two radiologists reviewed images from the MBI examinations and subjectively categorized background parenchymal uptake into four groups: photopenic, minimal-mild, moderate, or marked. Women with breast implants or a personal history of breast cancer were excluded. The association between background parenchymal uptake categories and patient characteristics was examined with Kruskal-Wallis and chi-square tests as appropriate. RESULTS. In 1149 eligible participants, background parenchymal uptake was photopenic in 252 (22%), minimal-mild in 728 (63%), and moderate or marked in 169 (15%). The distribution of categories differed across BI-RADS density categories (p < 0.0001). In 164 participants with extremely dense breasts, background parenchymal uptake was photopenic in 72 (44%), minimal-mild in 55 (34%), and moderate or marked in 37 (22%). The moderate-marked group was younger on average, more likely to be premenopausal or perimenopausal, and more likely to be using postmenopausal hormone therapy than the photopenic or minimal-mild groups (p < 0.0001). CONCLUSION. Among women with similar-appearing mammographic density, background parenchymal uptake ranged from photopenic to marked. Background parenchymal uptake was associated with menopausal status and postmenopausal hormone therapy but not with premenopausal hormonal contraceptives, phase of menstrual cycle, or Gail model 5-year risk of breast cancer. Additional work is necessary to fully characterize the underlying cause of background parenchymal uptake and determine its utility in predicting subsequent risk of breast cancer.

Optically measured microvascular blood flow contrast of malignant breast tumors

Microvascular blood flow contrast is an important hemodynamic and metabolic parameter with potential to enhance in vivo breast cancer detection and therapy monitoring. Here we report on non-invasive line-scan measurements of malignant breast tumors with a hand-held optical probe in the remission geometry. The probe employs diffuse correlation spectroscopy (DCS), a near-infrared optical method that quantifies deep tissue microvascular blood flow. Tumor-to-normal perfusion ratios are derived from thirty-two human subjects. Mean (95% confidence interval) tumor-to-normal ratio using surrounding normal tissue was 2.25 (1.92–2.63); tumor-to-normal ratio using normal tissues at the corresponding tumor location in the contralateral breast was 2.27 (1.94–2.66), and using normal tissue in the contralateral breast was 2.27 (1.90–2.70). Thus, the mean tumor-to-normal ratios were significantly different from unity irrespective of the normal tissue chosen, implying that tumors have significantly higher blood flow than normal tissues. Therefore, the study demonstrates existence of breast cancer contrast in blood flow measured by DCS. The new, optically accessible cancer contrast holds potential for cancer detection and therapy monitoring applications, and it is likely to be especially useful when combined with diffuse optical spectroscopy/tomography.

Radiotracer breast cancer imaging: Beyond FDG and MIBI

Radiotracer imaging with MIBI and FDG have shown the benefit of the functional imaging of breast cancer. Newer radiopharmaceuticals targeted to particular aspects of breast cancer biology will likely play an important role in directing more specific and individualized breast cancer treatment. Future studies will need to test the ability of SPECT and PET imaging to detect breast cancer, but also to assess target expression, identify resistance factors, and measure early response to treatment. This will require protocols designed to test the predictive capability of imaging in the setting of a therapy trial, a new paradigm for breast cancer imaging, for which radiotracer imaging is ideally suited.

Diffuse Optical Monitoring of the Neoadjuvant Breast Cancer Therapy

Recent advances in the use of diffuse optical techniques for monitoring the hemodynamic, metabolic and physiological signatures of the neoadjuvant breast cancer therapy effectiveness is critically reviewed. An extensive discussion of the state-of-theart diffuse optical mammography is presented alongside a discussion of the current approaches to breast cancer therapies. Overall, the diffuse optics field is growing rapidly with a great deal of promise to fill an important niche in the current approaches to monitor, predict and personalize neoadjuvant breast cancer therapies.

Single-photon-emission computed tomography (SPECT) with technetium-99m sestamibi in the diagnosis of small breast cancer and axillary lymph node involvement

BACKGROUND

In a prospective study we evaluated the accuracy, sensitivity, and specificity of single-photon-emission computed tomography (SPECT) technetium-99m (99Tcm) sestamibi scintimammography to differentiate between benign and malignant small solid lesions of the breast, and to diagnose axillary node involvement in patients with small breast tumors.

METHODS

We prospectively evaluated 172 women with a solid lesion of the breast less than 3 cm in diameter and no evidence of axillary lymph node involvement on physical examination, ultrasound, and mammography. Thereafter, all patients underwent excision of the lesion, and, if pathology was positive for cancer, quadrantectomy and axillary lymph node dissection independently by the results of scintimammography.

RESULTS

There were 92 patients with a benign lesion and 80 patients with cancer. SPECT scintimammography correctly identified all 80 patients with cancer; there were six false-positive cases and no false-negative cases for a test efficacy of 96.5%, sensitivity of 100%, and specificity of 93.5%. Forty-five of the 80 patients with cancer had axillary lymph node involvement and scintimammography correctly identified 39 of the 45 patients. There was one false-positive case and six false-negative cases for a test efficacy of 90%, sensitivity of 86.4%, and specificity of 97.5%.

CONCLUSION

SPECT scintimammography should be considered selectively in the preoperative evaluation of patients with small solid lesions of the breast. It allows correct identification of patients with cancer and identification of a significant number of patients with axillary lymph node involvement.

Advances in molecular imaging for breast cancer detection and characterization

Advances in our ability to assay molecular processes, including gene expression, protein expression, and molecular and cellular biochemistry, have fueled advances in our understanding of breast cancer biology and have led to the identification of new treatments for patients with breast cancer. The ability to measure biologic processes without perturbing them in vivo allows the opportunity to better characterize tumor biology and to assess how biologic and cytotoxic therapies alter critical pathways of tumor response and resistance. By accurately characterizing tumor properties and biologic processes, molecular imaging plays an increasing role in breast cancer science, clinical care in diagnosis and staging, assessment of therapeutic targets, and evaluation of responses to therapies. This review describes the current role and potential of molecular imaging modalities for detection and characterization of breast cancer and focuses primarily on radionuclide-based methods.

Investigation of blood perfusion and metabolic activity of brain tumours in adults by using 99mTc-methoxyisobutylisonitrile

OBJECTIVES

(i) To examine blood perfusion and metabolic activity of various brain tumours using radionuclide cerebral angiography (RCA) and single-photon emission tomography (SPET) after a single dose of Tc-methoxyisobutylisonitrile (MIBI). (ii) To examine if the inclusion of RCA can improve insight into the relative contribution of tumour perfusion to the uptake of MIBI shown by SPET, and to improve evaluation of tumour biology. (iii) To determine the value and the roles of MIBI in the management of brain tumour patients.

METHODS

Fifty adult patients (38 male, 12 female) with a total of 56 intracranial space-occupying lesions have been included prospectively, 37 of which were newly diagnosed and the remaining with signs of recurrence/rest of earlier resected and irradiated brain tumours. The control group consisted of nine volunteers with no evidence of organic cerebral disease. Scintigraphic examination consisted of a dynamic first-pass study lasting 60 s (3 s/frame) and two SPET studies (60 projections each, 25 s/projection), starting 15 min and 2 h after intravenous injection of MIBI. Regions of interest of the tumour and normal brain tissue were drawn on RCA and both early and delayed SPET slices. The following tumour/brain activity ratios have been calculated: (i) tumour perfusion index (P); (ii) early uptake index (E); (iii) delayed uptake index (D); and(iv) retention index (R). Analogous indices have been calculated from the same examinations performed in controls, reflecting maximal physiologic regional variations of perfusion and uptake in brain tissue.

RESULTS

Mean P of various brain tumours (low-grade gliomas 0.98, anaplastic gliomas 1.14, glioblastoma multiforme 1.20, metastases 1.09, lymphomas 1.08) differ little from each other and do not exceed maximal physiologic regional variations of cerebral perfusion (1.33), with the exception of meningioma (1.87, F=2.83, P=0.015). The receiver operating characteristics curve analysis of P showed that for the cut-off value of 1.45 the sensitivity for distinguishing meningioma from other tumours is 75%, specificity 87%, positive predictive value 33% and negative predictive value 97%. Mean E of malignant brain tumours (8.3, n=31, 23 primary, eight secondary), except anaplastic gliomas (3.5, n=5), differed significantly (P=0.02) from those of benign gliomas (3, n=9) but not from that of meningioma (11.9, n=4). The cut-off value for distinguishing malignant from benign lesions on the basis of E set at 4.8 resulted in sensitivity 67%, specificity 75%, accuracy 70%, positive predictive value 80% and negative predictive value 60%. D and R showed tendency of wash-out of MIBI from meningiomas, but otherwise did not improve the results substantially.

CONCLUSION

Integrated results of RCA and SPET with Tc-MIBI indicate that blood perfusion, blood-tumour barrier permeability and metabolic activity of the tumour are all very important for the resultant uptake shown by SPET. If the perfusion index is less than 1.45, then meningioma can be ruled out. Early SPET is recommendable for distinguishing glioblastoma from low-grade gliomas, as a complement to standard magnetic resonance imaging and/or computed tomography.

Glucose-induced alteration of accumulation of organotechnetium complexes accumulation in Pgp-negative tumor-bearing mice

The biologic and microenvironmental factors determining (99m)Tc sestamibi (MIBI) and (99m)Tc tetrofosmin (TF) uptake in breast tumors are incompletely understood, especially in P-glycoprotein (Pgp)-negative tumors. We analyzed the influence of glucose administration on the uptake and retention of MIBI and TF in Pgp-negative tumor-bearing mice in vivo. Twenty (20) mice bearing Ehrlich ascites tumor cell (EATC) xenografts were divided into four groups: (1) MIBI, (2) MIBI+glucose, (3) TF, and (4) TF+glucose. Glucose was administered (5.0 g/kg body weight) intraperitoreally (i.p.) 1 hour before scintigraphy. There were significant differences between the E-UPR MIBI and MIBI+glucose groups (p = 0.009) and minor differences in L-UPR between these groups (p = 0.04). There was a significant inverse correlation between E-UPR of MIBI and glucose levels (r = 0.71, p = 0.02). Comparing the four groups, the highest E-UPR was obtained in the MIBI group (p = 0.006). Other parameters were not different in the MIBI and MIBI+glucose groups and in the TF and TF+glucose groups. Increased blood glucose level affected the MIBI uptake of tumor tissue, particularly for E-UPR. We suggest that these findings were due to basically decreased blood flow and secondarily decreased extracellular pH. However, glucose administration did not affect TF.

99mTc-MIBI brain SPECT as an indicator of the chemotherapy response of recurrent, primary brain tumors

BACKGROUND

Malignant brain tumors carry a pejorative prognosis and necessitate aggressive therapy. Chemotherapy can be used in cases of tumor recurrence. With limited response rate and potential toxicity to chemotherapeutic treatment in patients with recurrent glioma, reliable response assessment is essential.

AIM

To define the place of 99mTc hexakis 2-methoxyisobutylisonitrile (99mTc-MIBI) Single Positron Emission Computed Tomography (SPECT) in monitoring chemotherapy response in recurrent primary brain tumors.

METHODS

In a retrospective analysis, thirty patients were investigated with MIBI SPECT. Imaging was performed 1h after the intravenous injection of 555 MBq of 99mTc-MIBI using a dedicated SPECT system. A MIBI uptake index (UI) was computed as the ratio of counts in the lesion to those in contralateral region. For all patients, we compared changes over time in UI with MRI and clinical data.

RESULTS

The changes in UI agreed well with the clinical and MRI-based assessments in 97% of cases. In 44% of these cases, the scintigraphic response appeared before the MRI response. In instances of treatment failure or rebound, the concordance between scintigraphy and MRI was 52%, and the scintigraphic response appeared before the MRI response in 48% of cases.

CONCLUSION

This study confirms our previous results obtained on a short series of patients with recurrent glioma, concerning the usefulness of MIBI SPECT in prediction of chemotherapy response. Moreover, in cases of tumor progression, we show that MIBI SPECT is an earlier indicator of escape from chemotherapy, an average 4 months before MRI changes.

Tumor-specific positron emission tomography imaging in patients: [18F] fluorodeoxyglucose and beyond

Biochemical and molecular imaging of cancer using positron emission tomography (PET) plays an increasing role in the care of cancer patients. Most clinical work to date uses the glucose analogue [(18)F]fluorodeoxyglucose (FDG) to detect accelerated and aberrant glycolysis present in most tumors. Although clinical FDG PET has been used largely to detect and localize cancer, more detailed studies have yielded biological insights and showed the utility of FDG as a prognostic marker and as a tool for therapeutic response evaluation. As cancer therapy becomes more targeted and individualized, it is likely that PET radiopharmaceuticals other than FDG, aimed at more specific aspects of cancer biology, will also play a role in guiding cancer therapy. Clinical trials designed to test and validate new PET agents will need to incorporate rigorous quantitative image analysis and adapt to the evolving use of imaging as a biomarker and will need to incorporate cancer outcomes, such as survival into study design.

Molecular imaging research in the outcomes era: measuring outcomes for individualized cancer therapy

Advances in molecular imaging, combined with the goal of personalized cancer therapy, call for new approaches to clinical study design for trials testing imaging to guide therapy. The role of cancer imaging must expand and move beyond tumor detection and localization to incorporate quantitative evaluation of regional tumor phenotype. Imaging study design and outcome analysis must move beyond metrics designed to measure the performance for detection to include measures of prognosis, prediction of therapeutic success, and early therapy response. This implies changes in how studies are carried and out, and importantly in the regulatory oversight of cancer imaging. Demonstration that a biochemical or molecular imaging method correctly and accurately measures a specific biologic feature should be sufficient for approval for clinical trials. It may be possible that a combination of imaging procedures known to accurately depict tumor phenotype may be prognostic, even if the individual study cannot be directly validated against patient outcomes. Therefore, it will be important to be able to apply a range of possible imaging studies to different targeted cancer therapy trials. Academia and industry must work together with regulatory agencies and payers to facilitate well designed clinical studies, with appropriate outcome measures, to test the effectiveness of imaging in helping to direct cancer therapy. These will assure the appropriate use of imaging to direct treatment and make an important step towards individualized cancer therapy.

Accuracy of ultrasonography and 99mTc-sestamibi scintimammography for assessing axillary lymph node status in breast cancer patients. A prospective study

AIMS

The aim of this study was to evaluate the sensitivity, specificity and accuracy of axillary ultrasonography (US) and (99m)Tc-sestamibi scintimammography (SSM) in patients with breast cancer (BC) undergoing curative surgery.

METHODS

A series of 77 consecutive women (median age 54 years, range 36-70) with primary BC underwent both US and SSM from 2 to 15 (median 4) days prior to curative surgery. The results of imaging studies were compared against the final pathology. Breast-conserving surgery with axillary node (AN) dissection was performed in 49 (63.6%) patients, and modified radical mastectomy in 28 (36.4%) patients, according to the tumour staging.

RESULTS

Final pathology showed 5 pT1bN0, 1 pT1bN1, 28 pT1cN0, 19 pT1cN1, 7 pT2N0, and 17 pT2N1 BC. Overall, 719 AN were removed of which 106 (14.7%) were metastatized nodes (median 3, range 1-5 per patient). The sensitivity, specificity and accuracy were 67.6%, 80.0%, and 74.0% for US, 78.4%, 85.0%, and 81.8% for SSM, and 91.9%, 92.5%, and 92.2% for US and SSM together, respectively. There was a significant difference (p<0.05) in the number of metastatized AN between patients with metastases correctly detected and undetected by both US (3.1+/-1.3 vs. 2.0+/-0.7) and SSM (3.2+/-1.3 vs. 1.7+/-0.7).

CONCLUSIONS

Although the results of each diagnostic tests are strictly dependent on the number of the metastatized AN, the combination of axillary US and SSM is a sensitive low-cost procedure that should be suggested in all patients with BC, when a preoperative evaluation of the AN status is required.

Current and future use of positron emission tomography (PET) in breast cancer

Positron emission tomography (PET) is a radiotracer imaging method that is increasingly used in both the clinical care of breast cancer patients and in translational breast cancer research. This review emphasizes current and future clinical applications of PET to breast cancer, and highlights some translational research using PET to elucidate the clinical biology of breast cancer. PET principles are reviewed, followed by a review of current applications of (18)F-fluorodeoxyglucose (FDG) to clinical breast cancer care. Finally we review work done with other radiopharmaceuticals beyond FDG designed to image a number of aspects of breast cancer biology, emphasizing those most likely to enter clinical trials in the near future.

Imaging recognition of inhibition of multidrug resistance in human breast cancer xenografts using 99mTc-labeled sestamibi and tetrofosmin

BACKGROUND

(99m)Tc-sestamibi (MIBI) and (99m)Tc-tetrofosmin (TF) are avid transport substrates recognized by the multidrug resistance (MDR) P-glycoprotein (Pgp). This study was designed to compare the properties of MIBI and TF in assessing the inhibition of Pgp by PSC833 in severe combined immunodeficient mice bearing MCF7 human breast tumors using SPECT imaging.

METHODS

Animals with drug-sensitive (MCF/WT) and drug-resistant (MCF7/AdrR) tumors were treated by PSC833 and by carrier vehicle 1 h before imaging, respectively. Dynamic images were acquired for 30 min after intravenous injection of MIBI/TF using a SPECT system, FastSPECT. The biodistribution of MIBI and TF was determined at the end of the imaging session.

RESULTS

MCF7/WT in the absence and presence of PSC833 could be visualized by MIBI and TF imaging within 5 min and remained detectable for 30 min postinjection. MCF7/AdrR could be visualized only 2-5 min without PSC833 treatment but could be detected for 30 min with PSC833, very similar to MCF7/WT. MCF7/AdrR without PSC833 showed significantly greater radioactive washout than MCF7/WT and MCF7/AdrR with PSC833 treatment. PSC833 increased the accumulation (%ID/g) in MCF7/AdrR 3.0-fold (1.62+/-0.15 vs. 0.55+/-0.05, P<.05) for TF and 1.9-fold (1.21+/-0.04 vs. 0.64+/-0.05, P<.05) for MIBI but did not affect MCF7/WT.

CONCLUSIONS

The feasibility of MIBI and TF for assessment of MDR expression and inhibition was demonstrated in mice through FastSPECT imaging. The results indicate that TF may be at least comparable with MIBI in recognizing Pgp expression and modulation.

Monitoring the response of large (>3 cm) and locally advanced (T3-4, N0-2) breast cancer to neoadjuvant chemotherapy using (99m)Tc-Sestamibi uptake

BACKGROUND AND AIM

(99m)Tc-Sestamibi (MIBI) scintimammography has an established role in the diagnosis of breast cancer. As a functional imaging technique, it may also be useful in assessing the response to chemotherapy. The aim of this study was to assess the effectiveness of the technique for this purpose.

METHODS

Twenty-six patients undergoing neoadjuvant chemotherapy for large or locally advanced breast cancer were monitored using the tumour to background ratio measured on MIBI scintimammograms. Patients were assessed and the size of the tumour was measured by callipers and ultrasonography before and at the end of treatment. Patients were assessed as complete, partial or non-responders. Following chemotherapy, patients proceeded to surgery with pathological evaluation of the operative specimen.

RESULTS

Twenty-four of the 26 patients showed a reduction in MIBI uptake on completion of chemotherapy. Residual tumour was demonstrated on the scintimammogram in four patients and all had significant residual disease on histology. In the remaining 22 patients, the final scintimammogram was negative, although three patients were assessed as non-responders and had large residual tumours on histology.

CONCLUSION

A positive MIBI scan is highly predictive of the presence of significant residual disease on completion of chemotherapy. However, a negative MIBI scan does not rule out the presence of considerable residual tumour. Whereas ultrasound and clinical assessment may underestimate the response to chemotherapy, MIBI imaging tends to overestimate the response.

Correlation between 99mTc-MIBI uptake and angiogenesis in MIBI-positive breast lesions

This study was undertaken to assess the correlation between the degree of accumulation and the washout of 99m technetium methoxyisobutylisonitrile ((99m)Tc-MIBI) and angiogenesis in MIBI-positive breast lesions. Twenty-eight patients (mean age, 51+/-11 years) with 31 breast lesions who underwent scintimammography were studied. Anterior, left and right prone lateral images were obtained 20 min and 3 h after the injection of 740 MBq (99m)Tc-MIBI. All breast lesions showed increased (99m)Tc-MIBI uptake. Early and delayed tumor to background activity ratios (T/BG) and washout index (early tumor uptake-delayed tumor uptake divided by early tumor uptake) were calculated. Vascular endothelium was immunohistochemically labeled using a biotinylated monoclonal antibody directed against the factor-VIII-associated antigen using standard biotin-avidin technique. Angiogenesis was evaluated by assessing the vascular surface density (VSD) and the microvessel number (NVES) within 10 randomly chosen areas. All pathological data were compared with early and delayed T/BG activity ratios and washout index of (99m)Tc-MIBI. Statistical analysis was performed using Spearman correlation test. There was no statistically significant correlation between the degree of angiogenesis and early T/BG (r = .287, P > .05 with VSD, r = .351, P > .05 with NVES), delayed T/BG (r = .277, P > .05 with VSD, r = .315, P > .05 with NVES) and the washout index (r = .268, P > .05 with VSD, r = .285, P > .05 with NVES) of (99m)Tc-MIBI in all breast lesions. There was no statistically significant correlation between the degree of angiogenesis and early T/BG (r = .235, P > .05 with VSD, r = .356, P > .05 with NVES), delayed T/BG (r = .181, P > .05 with VSD, r = .285, P > .05 with NVES) and the washout index (r = .158, P > .05 with VSD, r = .187, P > .05 with NVES) of (99m)Tc-MIBI in 24 invasive breast lesions. No statistically significant correlation was found between the degree of angiogenesis and early T/BG (r = -.036, P > .05 with VSD, r = -.107, P > .05 with NVES), delayed T/BG (r = -.500, P > .05 with VSD, r = -.429, P > .05 with NVES), but there was a high correlation between angiogenesis and the washout index (r = .893, P < .05 with VSD, r = .964, P < .05 with NVES) of (99m)Tc-MIBI in seven noninvasive breast lesions. Amount of (99m)Tc-MIBI uptake in breast lesions is dependent on several factors. Our study indicates that early and delayed (99m)Tc-MIBI uptakes in MIBI-positive breast lesions are not related to angiogenesis in both invasive and noninvasive breast lesions. But washout index of (99m)Tc-MIBI in noninvasive breast lesions is highly correlated with angiogenesis. (99m)Tc-MIBI scintigraphy does not seem to be able to indicate angiogenic property of invasive breast lesions.

To use MIBI or not to use MIBI? That is the question when assessing tumour cells

99mTc-sestamibi (MIBI) is a well-known tumour imaging agent. Its retention within tumour cell mitochondria is related to perfusion and to the magnitude of the electrical gradient, reflecting cell viability. Several internal cell factors modulate this uptake; for example, multidrug resistance membrane proteins (Pgp and MRP1) and anti-apoptotic BCl-2 protein of the outer mitochondrial membrane can limit retention of MIBI. At the early stage of cell apoptosis, the electrical driving forces of MIBI uptake are impaired, and influx and accumulation are reduced. It seems clear that MIBI can be used before treatment to detect drug resistance, assess anti-apoptotic status and predict treatment efficacy. Although it has been suggested that MIBI might be used to monitor tumour response to treatment, MIBI is unable to differentiate tumours with ongoing apoptosis from those developing drug resistance.

Evolving role of positron emission tomography in breast cancer imaging

18F-fluorodeoxyglucose positron emission tomography (FDG-PET) has been used for detection, staging, and response monitoring in breast cancer patients. Although studies have proven its accuracy in detection of the primary tumor and axillary staging, its most important current clinical application is in detection and defining the extent of recurrent or metastatic breast cancer and for monitoring response to therapy. PET is complementary to conventional methods of staging in that it provides better sensitivity in detecting nodal and lytic bone metastases; however, it should not be considered a substitute for conventional staging studies, including computed tomography and bone scintigraphy. FDG uptake in the primary tumor carries prognostic information, but the underlying biochemical mechanisms responsible for enhanced glucose metabolism have not been completely elucidated. Future work using other PET tracers besides FDG will undoubtedly help our understanding of tumor biology and help tailor therapy to individual patient by improving our ability to quantify the therapeutic target, identify drug resistance factors, and measure and predict early response.

Residual tumor uptake of [99mTc]-sestamibi after neoadjuvant chemotherapy for locally advanced breast carcinoma predicts survival

BACKGROUND

Studies utilizing serial [99mTc]-sestamibi (MIBI) scintimammography have reported accurate prediction of tumor response in patients with locally advanced breast carcinoma (LABC) undergoing neoadjuvant chemotherapy. The pathologic response of LABC to presurgical treatment regimens is a prognostic indicator of survival. The authors tested whether MIBI uptake posttherapy predicted survival.

METHODS

Sixty-two patients with LABC underwent MIBI scintimammography just before chemotherapy and 2 months after treatment initiation. An additional MIBI scan was performed if treatment lasted >3 months. The affected breast was imaged within 10 minutes after injection to reflect early uptake, which the authors have shown to be related to tumor blood flow. MIBI uptake was quantified using the lesion-to-normal breast (L:N) ratio. Most patients (93%) received weekly dose-intensive doxorubicin-based treatment. Disease-free survival (DFS) and overall survival (OS) were compared with posttherapy primary MIBI uptake and with other established prognostic factors for neoadjuvantly treated LABC, namely, primary tumor pathologic response and posttherapy axillary lymph node status.

RESULTS

Patients with high uptake on the last observed MIBI scan (i.e., the L:N ratio was greater than the median value) had poorer DFS and OS (P<0.01 and P=0.01, respectively). Residual MIBI uptake retained independent prognostic significance in preliminary multivariate analysis that included other established prognostic markers.

CONCLUSIONS

High primary breast tumor MIBI uptake after neoadjuvant chemotherapy predicted poor survival, suggesting serial MIBI imaging may provide a useful quantitative surrogate end point for neoadjuvant chemotherapy trials. Given the association between MIBI uptake and tumor blood flow, this prognostic capability may be related to retained tumor vascularity after treatment.

Assessment of Tc-99m sestamibi tumor tissue uptake under the influence of increased arterial oxygen saturation

The aim of this study is to investigate the potential effect of increased arterial saturation of oxygen in the magnitude of technetium-99m-hexakis-isobutyl-isonitrile (99mTc-MIBI) uptake in tumor tissue and to compare the results with those of conventional 99mTc-MIBI tumor imaging in the same patient with lung cancer. A total of 26 lung cancer patients underwent initial SPECT (I-SPECT) and after oxygen inhalation SPECT (O2-SPECT). The early (ER) and delayed ratios (DR) of O2-SPECT mean+/-S.D. were significantly higher than those of I-SPECT mean+/-S.D. (2.07+/-0.57 vs. 1.90+/-0.48 and 2.02+/-0.45 vs. 1.83+/-0.39, respectively). There are increased rates for the relative tumor uptake of 99mTc-MIBI by 9% for ER and 10% for DR on the O2-SPECT compared to I-SPECT. We found that 99mTc-MIBI uptake increased significantly in the tumor tissue with O2-SPECT compared to I-SPECT. In conclusion, 99mTc-MIBI scintigraphy is one of the main methods for differentiating viable and nonviable tissue fractions in tumors. We consider that 99mTc-MIBI uptake increase after oxygen inhalation is an indicator of positive acute cellular response of the tumor tissue to the rising tissue oxygen level.

Are there differences in breast tissue as a result of hormone replacement therapy? Can BEST imaging distinguish these differences?

Although it has been speculated that estrogen therapy may promote changes in breast tissue that could lead to cancer, no information exists as to differences in breast tissue for women who do and do not take hormone replacement (HRT) therapy. This study seeks to determine if there are differences in the tissue of women taking HRT in contrast to those who do not and if these differences are apparent in cases of breast cancer, cellular atypia, fibrocystic (FCD) disease and normal breasts. A total of 327 non-pregnant, non-lactating, pre-menopausal women were enrolled in the study, including 139 women who were actively taking HRT and 188 women who never had taken HRT. Using breast enhanced scintigraphy test (BEST) imaging, differentiation of breast tissue was determined. The groups were then analyzed to determine the effect of hormone therapy within each category of breast tissue. Differentiation between normal, FCD, cellular atypia, and breast cancer represent statistically significant differences (p.001) in metabolic activity and vascularity as demonstrated by differences in both average count activity (ACA) and maximal count activity (MCA). The distinction between cellular atypia and infiltrating breast cancer was statistically (p.05) different when looking at the maximal activity. Normal breast tissue and breasts with FCD appear more homogenous with no statistical differences in variability in breast tissue. Tissue variability is statistically greater when localized processes, such as cellular atypia and breast cancer, are present. Differentiation of cellular metabolic activity in breast tissue can be statistically determined when looking at the average and maximal metabolic activity. The final distinction between cellular atypia and cancer occurs when a focal region of breast tissue becomes metabolically more active than the surrounding breast tissue as shown by statistical increases in MCA. These findings are confirmed by the increased metabolic variability seen in regions of cellular atypia and cancer compared with the homogenous metabolic activity present in normal and fibrocystic breasts.